Weak knowledge of building control: February 2011

Tuesday, February 22, 2011

【 Weak current college 】 building ventilation basics

First, the concept and role of the ventilation system is to building ventilation buildings contaminated indoor air purification, directly or through the back to the outdoors, and then added in fresh air, to maintain the indoor air .environment meet the health standards process. .Visible, ventilation is one of the ways to improve air conditions, it is excluded from polluted indoor air and fresh air to the interior of two, the former called the exhaust, which is known as the air supply. .Exhaust and supply air to achieve a range of used equipment, devices, called the total ventilation system. .) Building ventilation is often used in the production and life, the former is known as industrial ventilation. . Second, the ventilation system in the form and classification ventilation system can be divided into natural ventilation and mechanical ventilation. .Natural ventilation is the use of the room, the density difference between hot and cold air and the room windward side, leeward side of the air pressure level to the exchange; mechanical ventilation is the use of ventilation equipment to the workshop (room) into or discharged within a certain amount of air, .the air exchange and processing. .According to the different range of ventilation, mechanical ventilation can be divided into general ventilation, local ventilation and mixing ventilation of three. .Which mainly depends on ventilation using harmful substances produced and spread the scope of the size of the large area of harmful substances is a comprehensive air, on the contrary can be partial and mixed ventilation. . During the calculation of natural ventilation, usually referred to as the external walls of the pressure difference inside and outside the residual pressure on both sides, such as a fenestrae and pressure is positive, fenestrae ventilation; residual pressure is negative, the fenestrae into the wind; when .fenestrae inthe residual pressure of zero isobaric surface, then the upper part of fenestrae into the wind, the lower part of the exhaust. .In buildings, will be zero residual pressure in the plane and the plane is called, therefore, located in and below the surface of fenestrae is a ventilation window, located above the surface of fenestrae, and is into the wind window. . Natural ventilation under hot, is the use of indoor and outdoor air temperature, the formation of different density, the pressure difference caused by indoor and outdoor air exchange. .When the building by the combined effect of wind and hot, in the role of buildings on the periphery of the hole is equal to its internal and external pressure by the wind and the hot sum. .Full use of wind, natural ventilation under hot modern green building is one of the important is to improve the indoor air quality, and create a comfortable environment, one of the measures take precedence. . Major equipment mechanical ventilation fans, air tube or air duct, air valve, air and dust removal equipment. . One fan 1. .Classification fan ventilation system for the fan is the flow of air in the course of transmission power to overcome the resistance loss of machinery and equipment. .In ventilation engineering is the most widely used centrifugal fans and axial fans. .By the centrifugal fan impeller, casing, drive shaft, the suction port and exhaust port and other parts. . 2. .Technical performance of the fan air flow ①: refers to the fan in operation, the amount of air delivered per unit time, in units of m3 / h; ② pressure: pressure generated by the wind turbine, in units of Pa .; ③ effective power: that fans send air power, which is equal to the product of air volume and pressure, in units of W. . Second, the ventilation ducts 1. .Duct materials and metallic materials it points to two major categories of non-metallic materials. . ① sheet metal material, stainless steel, aluminum and so on. . ② non-metallic materials with a glass plate, PVC board, concrete air duct and so on. . 2. . Duct cross sectional shape, round and rectangular two. . Third, the air valve valve installed in the duct or duct, primarily for regulating the air flow. .Valve in the ventilation system can be divided into a control valve, valves and automatic control valve. .' IV air intake and outlet sub-exhaust ports, mounted in the wind, the two ends of pipe or duct, according to different occasions, is divided into two forms of indoor and outdoor. . V. equipment to prevent dust pollution in the air from the atmosphere prior to purification, so that dust and air separation, process equipment such as dust removal equipment. .Main types of dust removal equipment, mechanical filter, filter type dust collector, wet scrubber, and four types of ESP. . .

Weak current College】【using PLL design-time problems --- Power By】【China power house network.

In order to meet ASIC design time schedule requirements, many engineers are phase-locked loop (PLL). PLL with some desirable features, including the clock multiplier capacity, clock duty cycle of correction capabilities, and clock distribution delay the Elimination of .capacity. These characteristics allow designers to use cheap low frequency crystals as its tablets, external clock source and the ensuing chip multiplier to generate any number of high-frequency internal clock signal. They also enable designers to keep the build-time window and chip clock .source edge alignment methods to control those Windows and chip interface clock-output delay. Although the structure and function looks simple, but full of various PLL hidden complexity, the complexity is likely to even the best designers. Today's ASIC technology in PLL .design is becoming more and more difficult, because the kernel thin oxide devices on the left of the threshold of power supply voltage peak reserves is more limited. These devices are often required to satisfy the objective of working frequency and maintain the flexibility of the supply voltage .. However, the power supply voltage peak reserves reduce the PLL of adverse impact noise characteristics. Structure and operation To truly understood PLL internal performance issues, we must first understand its structure and working principle. PLL's advanced structure seems to .be intuitive and straightforward, it consists of a phase detector, charge pumps, loop filter and voltage controlled oscillator (VCO). PLL circuit is started immediately after entering an "unlock" State because the VCO output frequency of the benchmarks and split frequency-independent .. However, the negative feedback loop by bringing together a cyclical reference input and output of the VCO segmentation clock rise between phase error to adjust the VCO output frequency. Integrated VCO phase error makes output frequency close to the base segmentation. When you .reach the "locked" PLL, phase detector detected phase error close to zero, this is because the VCO output frequency and phase partitioning and base frequency and phase. Because phase detector output only and VCO segmentation, therefore PLL output frequency than baseline and feedback input .frequency high N times, which makes the PLL to complete the multiplier. In addition, if the clock distribution is added to the feedback pathway, the PLL clock signal will be allocated at the reference signals, to delay the effective elimination clock distribution .. PLL internal function block may be represented by a variable number of analog and digital circuit, digital circuit even in extreme situations. However, whether the digital circuit or analog circuits, PLL completed the phase of the clock signal generation and calibration of .analog functions. And simulation function block, they are also faced with noise such as today's mixed-signal ASIC harsh environments common and unavoidable simulation technology challenges. If PLL cannot make good noise response, it will cause the output clock from its ideal values of time .transform offset. Output clock phase of these time transform offset is often called jitter (jitter). Jitter will build time by throwing an upset against the internal timing paths have disastrous effects, also by throwing an led the establishment of a data transfer .error-hold time disrupting effect tablet external interface instead. At the same time, other performance issues (such as instability, lack of adequate frequency range, locking problems and static phase offset) also affects the PLL design. Output jitter is one of the most .important issue, and is also the most rare PLL design to fit one of the topics addressed. By on-chip and chip-signal source to generate power and substrate noise with high data dependence, and may have a large number of including .low frequency, frequency component. Substrate noise often does not like power noise that have a large number of low-frequency components, because in the basement and no obvious between the power supply DC decline. In the worst conditions, PLL occur power noise level and .noise level basement respectively nominal supply voltage of 10% and 5%. The actual basal noise level depends on the IC manufacturing process used by the nature of the floor. In order to reduce the risk of a latch, many IC production technology .used in similar heavily doped base of light-doped extension. These substrates will tend to be long distance on the chip substrate noise transmission, making noise not readily available in through protection ring and additional base tap is being eliminated. Power and substrate .noise VCO output caused by the shift (which causes the accumulation of multiple cycles, until the settlement of noise pulse phase) which have an impact on the PLL, without affecting the PLL to the loop bandwidth of the qualified rate on frequency calibration error. As .a result of phase error can accumulate more than one cycle, so the worst case of output jitter is usually a square wave by low-frequency noise. If PLL underdamped, close to the loop bandwidth of noise even obvious. In addition, the PLL is .also close to the loop bandwidth frequency input jitter on zoom in benchmarks, especially when it owes to the damping. Output jitter types Output jitter can use several methods to measure-relative to the absolute time and relative to other signals .or relative to the output clock itself. The first method for measuring jitter is commonly referred to as absolutely jitter or long-term jitter; use the second method to measure jitter called tracking jitter or input-output jitter (this time the other signal means a .reference signals), if the reference signals is cyclical (and therefore no jitter), the output signal of absolutely jitter and tracking jitter are equivalent; the use of the third approach measurements of jitter (relative to the output clock) often referred to as periodic .(or cycle-cycle) jitter. In a single clock cycle (or at several clock cycle), cycle-cycle jitter can be as time transform deviation measurements (called the cycle-cycle jitter nth). You can use RMS output .jitter (RMS), also available peak-peak value. RMS jitter only those with a small amount of RMS with far more than the larger than the size of the edge of time displacement to indicate when the deterioration of smaller applications of worthwhile. .Such applications can include video and audio signals. Peak-peak jitter only for those who cannot tolerate any time beyond some absolute displacement of the edge of the application. Peak-peak jitter specifications in General is the only one that can be used to synchronize digital .system jitter specifications, this is because most of the establishment or maintenance time fault on chip operations are disastrous. Given the importance of jitter measurement method also depends on the application of PLL. In General, the cycle-cycle jitter PLL in all .applications are important. Track the jitter in the PLL output clock is used to enter another clock domain or a domain by another clock output of the data-driven or sampling applications (application interface is an example) is important. Long-term jitter in the .clock multiplier applications sometimes is important. Because PLL phase error in multiple cycles continue to accumulate, resulting from the power supply and substrate noise PLL tracking jitter may cycle-cycle jitter number times. However, as power and substrate noise suppression performance often .poor chip clock distribution network will generate additional noise. Therefore, to design the excellent PLL, the visible differences likely less than 2 times. PLL frequency doubling in cycle-cycle jitter is also available for each benchmark cycle first one or two output .cycle period of periodic disturbance and increase the disturbance is a phase detector system error. Jitter measurement can be very complex. We know, PLL must have noise mixed signal environment. Therefore, the equivalent of noisy environment measurement it is very important. .In a quiet, low-noise measurement in the PLL is optimistic and misleading results of jitter. Similarly, when human noise is added to the power of analog PLL, must pay attention to capture the worst cases of noise frequency content. For long term jitter .and tracking jitter, the worst case noise signal is a located on or below the loop bandwidth frequency (it usually is the minimum of PLL frequency low 20 x) square. For cycle-cycle jitter, worst case noise signal is an edge transition time is .less than the PLL output clock cycle and lower frequency than the base frequency of the square wave. The noise signal frequency bandwidth can be higher than the loop. The appended with additional noise PLL for characteristics of the circuit board sets and optional chip .set. External pulse generator will low frequency noise coupled to a square wave is used for power supply noise test AVDD (analog PLL power) or coupled to AVDD and at the same time for substrate noise test AVSS (negative analog PLL power). The noise .(its level to control the base potential VSS) at the same time to AVDD and AVSS, and only the noise to the substrates are equivalent. As long as you can reach the PLL power, you can pass a Board (including the production of printed .circuit board) for processing to enhance these features. Noise characteristics of processing Only surface mount components should be used for power supply noise coupling network. The Jitter measurement that prior to the conduct noise on the power characteristics. Although the .PLL is extra high frequency noise added to power, but the additional noise should be ignored, because it concerned with PLL output. Cycle-cycle jitter can be triggered by the PLL output, and observe an oscilloscope cycle after a similar move to .the edge of the measurement period. Tracking jitter and long-term jitter can be triggered by the PLL reference input, and observe the oscilloscope first PLL output edges move to measurement period. When inputs and PLL output signals from the same external drive oscilloscope for tablets ., you can eliminate those unrelated to PLL clock output pathway interference jitter. For both types of measurement should use the noise of relatively low baseline clock..

Weak current College】【air-conditioning --- after-school exercise --- Power By】【China power house network.

one choice (the alternative answers for each question, only a consistent meaning of the questions.) 1. air humidity index is divided into absolute humidity, moisture content, saturated absolute humidity and relative humidity.. Humidity .of the air used () to represent.. A.. Absolute humidity B.. Moisture content C.. Saturated absolute humidity D.. Relative humidity .; 2. Central air conditioning system basic structure, which from (), air handling and energy distribution systems and automatic transmission control system composed of four subsystems.. A.. Refrigerator B. .. Compressor C.. Heating and Cooling System D.. Generator 3. Air-conditioning system according to the device from the situation can be divided into a centralized, independent ., and () and other three types.. A.. DC-type B.. Semi-centralized C.. Closed D.. Recirculation . 4. Fan coil air conditioning system, fresh air supply, there are three specific ways: ① natural infiltration through the room supply of fresh air gap; ② through the external walls of the room () supply of fresh air; ③ .through independent. New air system supplies fresh air.. A.. Duct B.. Washer C.. Refrigerant pipe D.. Cooling pipe < .; BR> 5. Washer is a versatile air-conditioning equipment, air heating, cooling, humidification, () and other treatment.. A.. Dry B.. Removal of harmful gases .; C.. Dehumidification D.. Oxygen 6. Washer effect of processing on the air, if the water temperature is greater than the dry bulb temperature ta, will make the air temperature, .dry bulb temperature and wet bulb temperature difference between the ().. A.. Increased B.. Reduce C.. Unchanged D.. May increase may reduce the . 7. Electric humidifier air humidifier types are () devices.. A.. Steam humidification B.. Water evaporation humidification C.. "Dry" .; steam humidification D.. Electric spray 8. Dehumidification air handling method () do not need to set up renewable systems.. A.. Liquid absorption method < .BR> B.. Solid absorption method C.. Liquid absorbed by wet D.. Cooling by wet 9. High-speed air conditioning system equipment is the main ( .).. A.. Induction unit B.. Radial distributor C.. Axial air distributor D.. Face air distributor Second, fill in the .blank (please enter your answer on the line.) 1. Air conditioning system from the system, the system and the system in four subsystems.. 2. Conditioning treatment can be divided by air conditioning, air conditioning and air conditioning ... 3. Air conditioning cooling capacity by divided into air conditioning units, air conditioning units and air conditioning units.. 4. The situation by dividing the source of air, air-conditioning system can be divided ., and the other three forms.. 5. Common refrigerator with refrigerator, refrigerator and so on.. 6. Air conditioning system consists of three separate pipeline cycle is the cycle, the cycle and the cycle. .. 7. Using air-conditioning on the form of air humidification, and so on.. 8. Air conditioning air filters can be classified according to the principle role of the filter, filters, and three types .of filters.. 9. Chilled water system is responsible for the preparation of the chilled water refrigeration equipment transported to the air handling equipment, generally can be divided into systems and systems.. Third, the term resolution (see text box .below the noun enter your answer.) 1.. Air enthalpy 2.. Air enthalpy 3.. Fan coil air conditioning system .4.. Air-conditioning 5.. Process Air Conditioning four essay questions 1.. What is the central air conditioning system?. Air-conditioning system operation and management .of the main what?. Central air conditioning system operation method of regulating what?. The answer】【----------------------------- .---------------- .--------------------------------- .- central air conditioning system, centralized air handling equipment is set. composition of air conditioners, air handling the entire process carried out in air conditioners, and then transported through the air ducts and air distributor to each room, this air .conditioning system, also known as central air conditioning system.. Central air conditioning system service area, handling of air volume, technology is easier, and centralized device setup, management and maintenance convenience, can be adjusted according to seasonal changes in concentration, the lower .operating costs, which in the modern large buildings. to use more of this type of air conditioning system.. Common central air conditioning system: ① single-duct central air conditioning system, only set an air duct.. < .BR> ② centralized dual duct system, with two air supply pipe or two air conditioners.. Central air conditioning system operation adjusted as shown below.. Dew point adjustment means adjusting the content of the control ① change .heating (cooling) air heat ② adjust to the new air conditioning return air ratio ③ washer (or heat) the water temperature . ① regulation valve control coils with chilled water .or hot water in the flow ② fresh air bypass valve adjustment, change the heating or cooling fresh air ratio control humidifier dew point temperature ② ① controlled delivery. air vapor pressure . ③ moisture solid or liquid agent by wet air volume control adjust fan speed ② ① regulate air flow control valve --------- .- .----------------------------------------------- .--- .------------------- 2.. What fan coil air conditioning system consists of components?. The water and fresh air .supply system which specific form?. Fan coil air conditioning system which method of regulation?. What are the contents of the maintenance of fan coil?. The answer】【---------------- .----------------------------- .-------------------- .--------------- fan coil air conditioning system consists of one or more fans. coil units and cold and heat source supply system components; fan coil units by the blower, coil .and filter components, as air-conditioning terminal units, scattered in all air-conditioned room installation, the air can be processed independently,. The air handling hot and cold water needed to concentrate prepared by air-conditioned room, through the provision of water .supply system to each fan coil units.. Its water supply system has three specific forms: ① dual plumbing systems; ② three main systems; ③ four-pipe system.. .; Fan coil air conditioning system supplies fresh air, there are three specific ways: ① natural infiltration through the room supply of fresh air gap; ② the external walls of the chamber to supply fresh air ventilation ducts; .③ through a separate air system. supply of fresh air.. Fan coil air conditioning system air volume control and water regulation are two ways to achieve the adjustment of temperature and humidity control.. Fan coil air conditioning system with greater flexibility ... The unit can operate independently without disturbing each other, to meet the needs of different air-conditioning; system layout flexible, independent air handling, can also be concentrated in the system set a new air system, the unit used as a secondary processing .equipment, which constitute the semi-centralized. air conditioning system.. Fan coil air conditioning system operation and adjustment as described below.. (1) fan coil system, the local operation mode adjustment adjustment adjustment adjustment of water content regulation .of water supply pipe fan coil units installed in two or three-way valve to increase or decrease the flow of cold water coils, changing rooms. the ability of air to absorb heat regulate air volume control fan speed ., speed changes in the speed of air flow through the coil changes have taken place, the room air heat exchange coil in the volume also changes <BR. "(2) fan coil system, full-year operating a new air conditioning when .the system does not assume the indoor sensible heat load, just the fresh air and room temperature to the same treatment can be.. Can not afford the new air of room temperature regulation, and bear all the indoor coil sensible heat load by local regulation to .meet the indoor coil temperature and humidity requirements.. When the system will bear the new building envelope air temperature caused by heat cold (hot) load, the new air handling equipment available in the second heating (cooling) devices concentrate increased (decreased) the .temperature of fresh air.. Two-pipe fan coil system, at the same time can only be supplied to all the same temperature of the water coil.. Run in transition seasons, with the outdoor temperature decreases, the new wind load regulation should focus .on energy, the new air temperature gradually increased to offset the heat load changes.. At this point, the water temperature entering the coil will remain unchanged, fan coil units by water regulation, elimination of indoor short-term load changes.. < .BR> Maintenance of fan coil follows the table below.. Visits to check the device name the project cycle, project maintenance projects filter air filter water to clean the surface dirt 1 case / month .coil fin-tube surface dirt cleaning 2 cases / year Biography. corrosion of the heat pipe cleaning 2 times / year case fan impeller dust contamination, noise cleaning impeller 2 times / year drip tray .drip tray drainage network cleaning dust and water dish 2 times / year pipeline. insulation structure, automatic valve repair ------------------------- .-------------- timely action .--------------------------------- .-------- 3.. Air-conditioning system maintenance are what?. The answer】【------------------ .--------------------------- .---------------------- .------------- air-conditioning systems maintenance, property management company is. air-conditioning system during operation problems in time, to ensure the normal operation of air conditioning system, making use .of the building functions can be maximized.. In the air-conditioning systems maintenance process, often encounter some system failure (see table below), maintenance and management personnel should carefully analyze the cause of the malfunction, and the system adjusts the air conditioning system .to meet the design requirements.. Air conditioning system failure causes and solutions, see the "three, air-conditioning system maintenance." .---------------- .---------------------------------- .--------------- .--------------- 4. the maintenance of air conditioning units What are the main contents?. The answer】【-------- .------------------------------------- .------------ .----------------------- the maintenance of air conditioning units including the inspection and cleaning air conditioning units ... Inspection and .cleaning air conditioning units need to be shutdown.. Check the cleaning and the bottom coil corrosion and bolt fastening, and in operation at the filling oil.. Open the access door, air-conditioning unit internal inspection, remove the filter, check the coil .and fan blades pollution levels, and wipe thoroughly, will filter the outside clean, dry up later installed a solid, if found. damage should be promptly repaired or replaced.. Internal inspection is completed, close the access door open on the valve, then .wipe clean and air-conditioning unit outside the body, then the stand-alone test.. Single test run must pay attention to current, motor temperature, the transmission of vibration and noise are normal.. After the end of the test to run stand .-alone test, run test to check air temperature and return air temperature is normal, the inlet valve and the valve action is correct and reliable, the temperature setting is sensitive and so on.. All normal, the air conditioners can be formally put into .use.. ----------------------------------------------- .--- .------------------------------ 5. chiller plant equipment maintenance What are .the contents?. The answer】【------------------------------------------ .--- .----------------------------------- low-temperature heat medium is heated .in the heat, the heat absorbed after., into a high-temperature heat carrier (hot water or steam), sent by pipeline interior, the heat released through the cooling device, so that the indoor temperature; cooling after the temperature decreases, into .low-temperature heat medium (low water), and through the recovery. return heat pipe, for recycling.. This constant cycle, so as to continuously heat from the heat source to the interior, to complement the interior of the heat loss to maintain .a certain indoor temperature.. Refrigeration room is the heart of the whole building air conditioning system, refrigeration system is the arrangement of the specialized equipment room.. Generally run the control room, chiller room, chilled water and cooling water pump .house and work (for) a storage room rooms.. Good room management is the key to the normal operation of air conditioning systems, equipment, property management is an important part.. The management of the main cooling room is installed in one of the .management and maintenance of refrigeration equipment, refrigeration room management objective is to ensure the safe operation of refrigeration equipment.. Refrigeration room management is the key to the running state monitoring system, once the system failure, take appropriate measures in time and send a signal to .ensure the safe operation of the system.. Of refrigeration equipment in the room to have a reliable maintenance measures, equipment maintenance in the following table.. Content maintenance requirements do maintenance equipment lubrication equipment lubrication ① set to do people, point ., qualitative, quantitative, time, and all three filters to filter ② ③ To meet the requirements. Always check the filter, oil level, oil temperature, oil pressure and fuel injection pump, abnormal should always check .in time ④ lubricating parts such as bearing temperature, the sound is normal ⑤ common valve screw and nut. between regularly oiling lubrication, not commonly used valve screw, nut Department, to oil sealed; apparatus should always .check the oil regularly clean or replace the good inspection tour of the engine room equipment. ① Check the relevant parts of the work pressure, temperature, liquid level ② Check the drive belt, fastening .the chain and the smoothness ③ Check the fastening bolt is loose, any abnormal vibrations in equipment operation and noise ④ Check the control measuring instruments and the work regulators ⑤ Check the cooling system .work; check valve, brake and emergency alarm device is a good ⑥ check the security guards and railings of the check is good ⑦. whether the leakage of the sealing point .① civilized production must be responsible operator equipment, piping, instrumentation and careful job cleaning the environment, improve health, so no oil, no fouling, shaft. see the light, ditch bottom, the device see the insulation layer anti-corrosion qualities < .BR> ② ③ to maintain complete and timely elimination of run, run, drip, leak ④ fill each shift should run record, good equipment. The shift relief work ----- .-------------------------------------- .----------- .-------------------------- ..

【 Weak current College 】 inspection of air conditioning thermostat---Power By 【 China power house network 】

When the air conditioner is not working properly, you will need to check compressor start relay, thermal and over-current protector and capacitors, you must check the electrical control system is very important to control the protection and enforcement components — the temperature control in the master selection switch. Here are some common thermostat for rapid detection method.

First, the bellows-type or diaphragm type temperature controller

1. symptoms: contact bad or burned, causing the circuit can't reach; contact frequently starting arc adhesion, causing the circuit can't fault; thermal cavity temperature sensor for leak, causing the contacts cannot control the actions and lose.

Maintenance: the thermostat knob is in the opposite direction of rotation, several times, using a multimeter R×l stalls measuring temperature controller powered by two terminals, resistance is small, that contact is normal; if resistance, that contact is bad; if not, may be the temperature sensor for leak. If leakage can be first Visual inspection, observation of thermal head seal welding head is cracked, the sensor is damaged and crack, heat pipe has no bending trace, and then put the sensor placed people 30 ~ 40 ~ C warm water, test contacts closed, if the contact is still not closed, indicates that the sensor within the Thermo agent has been leaking out; if contact can be closed, then the sensor shall be removed from the water, put in the low temperature for a period of time after the contact has broken, the range of thermostat thermostat described incorrectly, you can adjust the temperature range of the adjusting screw rectifying, counterclockwise l/2 circle and try again.

2. failure phenomenon: temperature controller appears as a result of arcing contacts after adhesion. contact does not automatically jump to open, you cannot shut down the compressor.

Maintenance methods: put the sensor in two-door refrigerator storage room (5-lO ℃), the measuring temperature controller two terminals is disconnected. If disconnecting the. indicate contact adhesive, available flat blade screwdriver disconnect stirring the mechanical force-contact; if contact can jump off, table H-thermostat for temperature control range low drift and clockwise adjust temperature range adjustment screw.

3. failure phenomenon: temperature sensor for leak.

Maintenance methods: hot towel to heat pipe heating and the knob to the lowest temperature, multimeter measuring temperature controller is connected to the switch. If the switch is blocked. the thermal agent has been compromised, you should replace new thermostat.

Second, hot and cold-temperature controller

Electric-type air conditioners in the thermostat, contact control box has two sets of contact agencies (cold-contact and heat-contact), using the same thermal bellows control on cooling and heating degree. Its symptoms and inspection methods and ordinary thermostat are basically the same, but note that you should also check cooling load, thermal load switching is sensitive, i.e. in the refrigeration compressor should be connected to the location, the location in the heating circuit should be connected to the electric heater circuit.

3. defrost temperature controller

Defrost temperature controller is set in a hot-air conditioner control circuit for switching solenoid valve components. Its heat pipe installed side heat exchanger coil. when winter heating, outdoor side heat exchanger Frost layer thickening the temperature is below a set value when defrosting controller-contact action. Disconnect the solenoid valve £ ® the original heating cycle into a refrigeration cycle. Common structure there are two forms: one is the thermal bimetal: one is the normal temperature controller. Detection method is part of the temperature sensor is placed in the corresponding temperature of water or air, multimeter measuring two terminals is disconnected or conduction can know good or bad!. Thermal bimetal thermostat is also used to control indoor side against the cold wind.

4. heat resistance

Electronic thermostat or microcomputer control of the air conditioner, have made a thermistor sensor components. Thermistor is their resistance with temperature changes and significant change in the component £ ® for air conditioner return air temperature 10-lap direction of thermistors. General characteristics with a negative temperature coefficient: resistance with temperature increase and decrease. Specific to a certain brand of empty Yuan for the use of the resistance of the thermistor, it varies with temperature-dependent properties are generally draw in random directions into the chart for detection, detection can under certain circumstances, using a thermometer and a multimeter for semiconductor measurement. controlled temperature sensing characteristic or characteristic value table to determine whether the normal performance when aging, Thermistor, namely temperature drift and the resistance of the correspondence between the change and should be replaced with new thermistor sensors.

The system is not functioning properly or long term will have failed after aging. In the repair process can sometimes take a replacement method, which uses a good same model, same specifications thermostat replacement saves maintenance time and can easily distinguish the thermostat is good or bad.

Weak current College】【control valve selection and maintenance-of-Power By】【China power house network.

First, the control valve selection

A, the importance of the control valve selection

Control valve is automatic control system of the actuator, its application quality direct response in the system of quality. As process control terminal symbol, its importance than in the past have been updated. Control valve applications or bad quality, except for the product itself, the user is correctly installed, use, maintain, correct calculation and selection are very important. Because the selection of the mistake, resulting in the system can stop, or even putting-, so for users and system designers should recognize the importance of the valve at the scene, you must control valve selection caused enough attention.

B, the principle of control valve selection

1, according to the technological conditions, select the appropriate structure and materials.

2, according to the technological characteristics of the object, select a control valve's flow characteristics.

3, according to the process operation parameters, select the appropriate control valve diameter size.

4, according to the requirements of the process, select the auxiliary device.

5. reasonable choice. Executive Body of the response should be able to meet the technological

To control the travel time of the request: the selection of control valve actuator should be covered with foot valve stroke and technology on the disclosure of rating requirements. In some occasions, such as selection pressure control valve (valve), consideration should be given to the actual possibility of pressure differential for appropriate amplification, which requires implementing agencies can provide larger forces. Otherwise, when the exception occurred on technology, the control valve before and after the actual pressure differential is large, occur off not or can not be opened.

Second, the control valve accessories

In the production process control system for valve raise various kinds of special demand, therefore, the control valve must be equipped with various ancillary installations (annex) to meet the needs of the production process. Control valves accessories including:

1, valve positioner for improved control valve performance characteristics, realization of the right positioning.

2, valve position switch to display the upper and lower limits of the valve stroke work location.
3, pneumatic control valve-valve when sources of failure, keep the valve is in the air source fails before the opening position.

4, solenoid valve for gas solenoid switch, guarantee the valve in a power failure while the valve is in the desired security opening location.

5. hand wheel mechanism when control system controller fails, you can switch to manual mode operation valve.

6, pneumatic relay enables executing agency action to speed up and reduce transfer times.

7. air filter regulator used to purify the air source, adjust the air pressure.

8, storage tank guarantee when the source of failure, so no spring of cylinder piston executive agencies to be able to work will control valve action to fail safe location. Its size depends on the size of the cylinder, valve action time requirements and the working conditions of the valve and so on.

In short, the role of the attachment is to make the control valve function better, smarter and more complete.

Third, the control valve maintenance

Control valve has a simple structure and action simple and reliable, but because it has a direct contact with the process media, its properties directly affect the system's quality and environmental pollution, control valve must be regular maintenance and periodic maintenance, especially for the use conditions and important occasions, should pay more attention to maintenance work. Focus inspection site

1, valve wall

For use in high-voltage differential and corrosive media in the control valve, the valve interior, diaphragm valve of diaphragm is often affected by the impact and corrosive media, must be focused on checking the pressure resistance, corrosion resistance.

2, valve seat

Control valve, due to media infiltration, fixed seating surface with thread within the vulnerable to corrosion, check for loose seat should be noted. The high differential pressure of the valve under work, you should also check whether the flush valve seat sealing surface.

3. the valve

The valve is regulating the work of moving parts, the media's most serious erosion, corrosion, maintenance time to seriously check valve parts are corrosion, wear, particularly in the high differential pressure of the valve wear more serious (due to cavitation phenomenon), it should be noted. When the valve damaged should be replaced, in addition you should also note the stem if there is a similar phenomenon, or loose with the valve connection.

4, diaphragm "O"-rings and gaskets. Should check control valve diaphragm, "O"-shaped gasket degradation, fissure damage.

5, sealing packing

It should be noted that PTFE packing and sealing grease degradation, combined with surface damage, should be replaced when necessary.

【 Weak current College 】 Central air conditioner selection method

Summary: China is now the market situation in the central air conditioning was good, the growth in number but as competition leads to lower prices. The average price of refrigerators have fallen significantly, but also reflects the progressive miniaturization trend of refrigeration. And details how the selection of central air conditioning.
Key words: central air conditioner market selection refrigerator

The first chapter of the China refrigeration units and large air conditioning equipment trends

China is now the market situation in the central air conditioning was good, the growth in number but as competition leads to lower prices. The average price of refrigerators have fallen significantly, but also reflects the progressive miniaturization trend of refrigeration. 

Air blower plate Tube or major end products. Air handling unit (combined air conditioner) and other terminal equipment increased, but their fan coil of mainstream status no significant threat.

First, the refrigerator specifications

According to BSRIA (UK) survey to calculate the product of cooling capacity, large equipment market size reduces (1000kw, 285Reftons); but be value calculation, cooling capacity in 401kw (114ton) and 401kw above refrigerator in 2000 accounted for 67%, or $ 4.24 billion. And only 1000kw total sales above $ 3.02 billion, accounting for total sales by 47%.

In recent years, a large number of small refrigerator, mainly scroll-type of application in the household, etc. Medium-sized refrigerator sales are on the rise, based on the following reasons:

• Screw by designers and users more and more popular. 

● Have a multiple small units instead of one large unit by tendency. So that only some of the load conditions, reducing the operating frequency to achieve energy savings and greater stability. 

Through State-owned enterprise reform and restructuring, very large industrial project investment is reduced, in the past, this is the main areas of large refrigerator. In other areas, there are large foreign-funded enterprises to invest in new commercial buildings, factories, etc. 

Adopts the foreign advanced technology drives higher performance of the emergence of new products, mainly in the screw and centrifugal compressors, heat exchangers and electronic control. At the same time, the absorption chiller technology is headed by domestic manufacturers develop and improve.

Second, the type of refrigeration

In the vast majority of Chinese sales of refrigerator is air cooled, accounted for 76% of the entire market, and in 1997, cold water unit accounted for 67% of the market. This marked an important change, this trend will continue.

Type 1, refrigerator

A clear trend is the application of the screw and scroll technology. Piston machines in 3 years ago, now the dominant market share but declining sharply to 15%. 

Absorption-type unit due to the improvement of electricity supply and rising oil prices, the market is shrinking. 

Because not too many such as airports, hospitals and high levels of office buildings and other large construction projects, centrifuge market in 2000 remained at around 850 sets.

1.1, absorption chillers

1.1.1, profile: absorption chiller development in large part to the decision by the energy structure of the State. In the past 2-3 years, the absorption chiller market due to the shrinking of the following reasons:

● Increase of supply of electricity;

● Oil price increases;

● Electric chiller replacement for HCFC (piston, screw and scroll, centrifuge);

● Electric chiller efficiency.

A brief history of 1.1.2,

Until the mid-1990s, the steam engine is mainly provided by domestic manufacturers, and direct-fired units are imported from Japan. Jiangsu shuangliang is the leader in China. Although shuangliang was United States te in the later half of the establishment of a joint venture, and the two sides to 99 years (actually is in March 2000, the translator's note) has lifted the joint venture relationships, shuangliang has been ranked first in China absorption chiller manufacturers. Shuangliang and has begun to expand overseas market. 

In the early 1990s, China manufacturers vision launched the fired absorption chiller (mainly oil). Fired machine initially adopts low calorific value of gas. As the gas pipeline network in large cities, burning natural gas-fired air conditioner is increasing.

1993-1995 market boom period. Under the Montreal Protocol, China announced the phasing out of the year 2006 and industrial refrigerators use CFC. due to the massive use of electric refrigerator no new refrigerants, as an alternative, the absorption chiller is rapidly expanding. In addition, the Government put the absorption chiller solutions at the time of application as the power shortage in a way, therefore also encourage the development of absorption technique. In this way, the market demand suddenly turned to absorption chillers, has also attracted dozens of competitors to enter the absorption chiller market. 

1995-1998 period of market stability. This period of market gradually moving towards maturity. Technology to improve rapidly, many market participants. Shuangliang, ambitious, Sanyo and Kalee dominated the market. Yantai EBARA and LG tonghe. Vision direct burning machine in the expansion. 

At the same time, after replacing electric refrigerator refrigerant, is gradually regain lost market. From 1998 to date, the absorption chiller is facing fierce competition in electric refrigerator: power supply increases, the price decline in some areas. Worse still is that oil prices are rising. Scroll and screw due to performance and efficiency reasons why more and more popular. HighFor initial investment and energy supply of convenience, cause some customers turned to other forms of refrigerator.
br>1.1.3, supply

Absorption chillers are the only proprietary central air conditioning products. China has become the subject of Japan's second largest absorption chiller production countries. 

The vast majority of domestic demand is met by domestic production. The number of export was minimal. But as shuangliang and far-sighted overseas expansion strategy execution, exports will increase. 

Of particular concern is the Kalee's strategy. It has decided to close the other factory and Shanghai a cold factories as global absorption chiller market supply center. Therefore, it will also promote exports. 

1.1.4, fuel analysis

Chiller in China became popular due to heating boilers is not required, thus saving costs. In major cities, absorption chillers are fired in the majority. In a region where heat or steam/hot water-mill.

Due to the high oil prices and the construction of gas networks, gas has become the fuel of chiller, and future trends. While the current single-effect absorption chiller in China is very rare. 

1.2, centrifuge

Centrifuge market capacity approximately 700-1200 wandering between computers. Because based on large-scale infrastructure projects, and in the last 2-3 years of large-scale infrastructure projects is not very much, so the market is a centrifuge dull. 

Centrifuges are characterized by the use of water cooling and is usually greater than the large unit 800kw. 

Market are United States brand such as York, Kalee, tring and monopolized by McQuay. Import unit about the entire domestic market share of 50% of this is the highest in all of the refrigerator. 

Since 1999 the surplus electric power supply, the sealing of the steady growth of the market of the centrifuge. Domestic manufacture of unit also introduced advanced technology. Hezhong Kalee had in Shanghai Assembly and manufacturing of hermetic compressor, and also with other parts of the joint venture to assemblethe refrigerator. While other companies or assembled by the compressor. 

1.3, screw

Screw machine market is growing. Because it is considered to have high performance and low noise, less than the models encroached 800kw piston machines share. Even greater than 800kw models, compared with centrifuge and flexibility features. Therefore, screw and more users and Design Institute. 

Screw another factor of growth in recent years for medium-sized refrigerator needs increase. In the industrial field investment principal is private enterprises and joint ventures, their factories mostly medium-sized buildings. Screw set of nature is the best choice. 

Screw machine group mostly water-cooling. But the forced-air cooling type, especially air source heat pump unit and gradually grow. Hitachi, Daikin, York, Tring, Kalee, dunhanbushi, McQuay and JI-young is a major participant in the market. However, approximately 1/4 of the import of the unit. All of these manufacturers are assembled in a factory in China. Hitachi will be held in Guangzhou Wanbao production unitary air conditioners air cooled screw, Guangzhou Wanbao has been producing water cold conditioning. 

There are also many local manufacturers from Bitzer, Hanbell, Fusheng, Refcomp, compressor or homemade of compressor to design and assemble the refrigerator. These manufacturers is Dalian bingshan, Zhejiang Trump, Shanghai Richfield, Chongqing jialing, Wuhan cold machine factory, etc. Italy brands such as RC, Climavereta, a well-known Clivet. Taiwan manufacturers Kuenling also in April last year established a factory in Shanghai. 

1.4, piston machines

Piston machines are scroll and screw segmentation of the market. And you've exited from the domestic market, the only commercial and industrial areas remain some market share. Most of the unit's cooling capacity lower than 350kw and the proportion of the heat pump. Kalee, York, McQuay and other domestic brands such as Dalian bingshan, Nanjing Wuzhou, JI-young and Yantai Moon in a leadership position in the market. In view of domestic technology has matured and the shrinking of the market, imported units are rare.

1.5, scroll

Copeland, Danfoss is China's largest suppliers of scroll compressor. The majority of scroll compressor for air conditioner unit.

In 2000, the China market total sales of approximately 2 million scroll chillers. The majority of the cooling capacity is 5-35kw, mainly for the Villa and more room apartment. As a residential central air conditioning, scroll the main types of machine market in 1999 and 2000 began to prosper. The next few years the situation remains good. 

Cooling capacity greater than 35kw of unit for small commercial areas such as Office, small hotels, theatres, etc. This type of most of the Vortex machine is modular Vortex machine. Only Te can provide a single large scroll units. 

2. recent trends

In the majority of Chinese sales unit is domestic manufacturers or joint ventures in China. Key components are now also localized. China refrigeration and air-conditioning industry with low cost and continuously improve the quality of products, are gradually shifted from import-export-oriented.

2.1, steam compression type (volumetric) refrigerator

Since the Government's management and the mild climate, air source heat pump is the darling of the Yangtze River basin in the market. Winter for heating of coal-fired boilers in the area south of the Yangtze River has been banned. Therefore, including room air conditioner, mainly used for refrigeration,Also heating with heat pumps by the region's favorite. Heat pump for heating, so you can save the boiler. Direct-fired chiller applications. 

With piston or scroll compressors for refrigeration capacity is 5-10RT small air cooling or heat pump chiller's most used residential central air conditioning system. Cooling capacity is 20-400RT air-cooled, airsource heat pump and cooling piston, scroll or screw machine mainly used in commercial buildings. 400RT more vapor compression refrigerator mostly semi-enclosed centrifuge group. 

Because of its high efficiency and high reliability characteristics, closed screw is preempting piston machine market. At the same time as the primary surplus and electricity investment low factors also encroached on absorption chiller market. But screw compressor can reduce the cost of localization.

2.2, absorption chillers

Power shortage in the past, the Administration on the control of the total electricity consumption, but also no absorption of sales to any special preferential policies. Absorption of purchase by the user based on their personal economics on product quality, reliability and service assessment. 

According to industry statistics, 2000, the absorption capacity of approximately 2600 units (including steam double 50%, fuel oil chiller 25%, gas-fired air conditioner 25%). Single-effect and very little water-mill. 

In 2000, shuangliang, ambitious and Dalian SANYO is considered a market leader. Yantai EBARA and LG with and increased market share, but lost Kalee market share.

In 2001, the Government established a new absorption chiller national standard, which provides cooling water inlet temperature from 32 ° c to 30 ° c, while the new chiller in refrigeration at LHV State COP minimum 11 (on HHV State = 10). These indicators are considered even if the existing model is also very easy to reach.

2.3, refrigerant issues

Since 1995, China is the world's largest CFC use State. Under the Montreal Protocol, China plans to phase out the use of CFC within 10 years.

CFC phase-out plan in China:

Automotive air conditioning systems to the commercial and industrial refrigeration in 2002 to 2006 conditioner 2010

Now use the refrigerator HCFC-22 will be using the HFC-407C or-410A piston and screw and scroll machine replacement. Refrigeration units for refrigerant replacement ratio of unitary air conditioning unit to replace the much faster. Central air conditioning systems from the CFC (R12) replacement for HCFC (R22) has been completed. 

Piston, screw and scroll-the vast majority of still use R22. market has some use R134A and individual use R407C, usually the customer requirements. 70% of the centrifuge has shifted from R22 R134A. There are other alternatives such as R407C and R123. However, R134A will be the most common choice.

2.4, modular air conditioning unit

Commercial and residential use of modular room air conditioner market capacity of approximately 80 million-100 million units/year. More than 80% are air cooled split. 10% is water cooled Interior unit. Mostly local Assembly of the main manufacturers: Chunlan, Haier, gree, midea, kelon, JI-young and South China. This part of the market is growing rapidly. 

Beauty from two years ago, the introduction of Toshiba's technology has begun to manufacture Kalee and sell VRF air conditioning system. Haier technology from Toshiba Kalee. Initially, the main manufacturers of Japan Daikin to export from Japan, but because of reduced tariff price competitiveness, Daikin has decided this year to begin production in China (see August JAPN). 

Hitachi has announced that a Hitachi air conditioning and refrigeration equipment (Guangzhou) company plans to double the capital. Used to increase the air cooled chiller and the localization of the modular air conditioning unit.

Summary of chapter host selection

(—) Summarization of the chiller class

Chiller is the heart of the central air-conditioning system, the correct choice of chillers is not only a guarantee of success of engineering design, and operation of the system also produces long-term impact. Therefore, the chiller choice is an important task.

1. Select the chiller considerations:

★ Building uses.

★Various chiller performance and features.

¡Ï local water sources (including water temperature and water quality), power and heat (including the source type, nature and taste).

★ Building annual air-conditioning cooling load (thermal load) distribution.

★ First investment and running costs.

¡Ï on freon refrigerants restricted period and the possibility of using alternative refrigerants.

2. water chillers selection considerations:

Taking into account the above factors, the selected water chillers, you should also note the following points:

★ Large central air conditioning system with cooling source, use the structure is compact, small footprint and compressors, motors, condenser, evaporator and automatic control components are assembled in the same frame of chillers. On small full air conditioning system, the use of direct evaporative condensing unit.

¡Ï on suitable heat source especially heat or waste heat and other places or places of power shortage, the use of absorption chiller.

★ Refrigeration units generally use 2-4 bed suitable for small and medium scale to choose 2, larger optional3 bed, large choice of 4. Unit to consider their mutual between as spare and toggle the use of the possibilities. The same engine may use different types, different capacity unit mix of modular programmes to save energy. Parallel operation of the unit at least select a higher degree of automation, tuning performance better, can guarantee part of the load to the machine running efficiently. Piston chiller should preferred multi-head automatic control for chillers.

¡Ï selection driven chillers, cooling capacity when the stand-alone air conditioning φ ＞ 1163kW, use centrifugal; φ = 582 ~ 1163kW, use centrifugal or screw; φ "582kW, use piston.

¡Ï power driven chiller COP of refrigerating factor than the absorption chiller of high thermal conductivity, the former for the latter two times more. Energy from low tohigh in order to: centrifugal, screw, piston, absorption (foreign unit screw-centrifugal before). But various unit has its own characteristics, use it.

★ Choose refrigerator should consider their environmental pollution: noise and vibration, to meet the requirements of the surrounding environment; second, refrigerants CFCs on atmospheric ozone layer damage and the size of the greenhouse effect, with particular attention to the disabled timesheet CFCs. Direction in the prevention of CFCs pollution absorption chillers have a distinct advantage.

¡Ï without special room location or air conditioning retrofit retrofitted to consider modular chillers.

★ Made possible. China refrigeration equipment industry in the last decade has been developing rapidly, the vast majority of product properties are close to the international advanced level, in particular small and medium-sized chillers, and imported products, and prices have incomparable advantages. Therefore, other things equal, priority should be made by chillers.

(B) heat pump class

★ Heat pump units of cooling load calculation method and the conventional air conditioning systems, heat load calculation method in much the same heating system, regardless of the outdoor air heat consumption;

¡Ï selection when the local availability of water resources (including water, water temperature and water quality), power and heat (including the nature, quality or low heat source);

★ Air source heat pump water temperature is 45 ° c, fan coil units and combined air-conditioning units and other samples are available in quantity of heat, usually to 60 ° c for the water, so that must be the amount of heating equipment be amended;

★ Choose heat pump units, should generally be to winter heating load as select by, at the same time check the cooling load in summer;

★ For shopping malls, restaurants, and other internal load and fresh air load extremely large buildings, due to the heating load generally only cooling load of 60%-70%. Therefore, the use of heat pump unit and single cold units combined supply way, for example, "3 x 1" mode, i.e. 3 Typhoon heat pump units plus 1 single cooling unit;

★ Air source heat pump rated for quantity of heat, are usually standard conditions (environment temperature t0 = 7 ° c water temperature ts = 45 ºc, when the ambient temperature is below 7 ° c, the quantity of heat will be drastically reduced. General reductions as follows: t0 = 5 ℃, the percentage decline to 5%-8%; t0 = 3 ℃, the percentage dropped to 12 per cent to 14 per cent, t0 = 0 ℃, the percentage dropped to 25 per cent to 32 per cent; t0 =-3 ° c, the decline in the percentage of 45% and 50%; t0 =-5 ° c, 55% decline in the percentage ~ 65%. Note: in accordance with the standard condition of air-cooled heat pump units, in fact, in a 3 ° c, the following is not functioning properly;

★ Air-cooled heat pump units of a single smaller capacity, should be applied to small and medium-sized projects;

★ Winter outdoor air temperature during the day is always higher than the night. Therefore, outdoor heating calculation temperature long tw =-3 ° c in the daytime only, for use in buildings such as office buildings, shopping centres, etc, you can use an air-source heat pump unit. For a full day (24 hours) requirements for heating buildings, when using an air-source heat pump should be treated with caution;

★ Water source heat pump system is suitable for many residents of apartment buildings and an area of larger large villas. The design should ensure that the system flow calculation accuracy. For cooling towers, pumps and other equipment selection;

★ In relative humidity higher areas, selection of the heat pump, should pay special attention to the analysis of operating conditions, and to take effective measures of defrosting.

(3) in the engine room of the ground source heat pump parts

1. heat pump in the engineroom the heat pump unit part can refer to the following steps for selection:

★ Water source heat pump unit capacity is not too large. Central air conditioner cold heat source equipment selection, equipment cooling (heat) about design cold (hot) load 1.05 ~ 1.10.

★ Water source heat pump unit type, should be as close as possible to the design of cold (hot) load. If set too large, the run time is short, start frequently. Unit capacity, long-running, conducive to dehumidify.

★ Closed water system water temperature, water temperature lower summer requirements, with the aim of improving energy efficiency, reduce power consumption. In winter the water temperature is not too high, because the temperature is high, although high cooling capacity, but also the high power consumption, the efficiency coefficient of variation.

¡Ï design-time objects that you want to consider building heating and air conditioning while using coefficient. At the same time using the coefficient value and building types, and the number of buildings, through theoretical and measured. The residential air-conditioning load calculation using coefficient of lists of data is: when the household page〈 100 households, the coefficient of 0.7; when the number of 100-150 households, 0.65 ~ 0.7; when the number of 150 ~ 200 households when 0.6.

2. outdoor ground heat exchanger parts can be selected with reference to the following steps:

Geothermal heat exchanger selection including the type and structure of selected, for a given building site conditions should try to run the design to meet the needs of the lowest cost. Geothermal heat exchanger selection primarily concern the following aspects:

★ Geothermal heat exchanger of the layout, including tube and bind methods, as shown in the figure. Tube can be divided into horizontal and vertical. Select the size depends on the site, the local soil types and mining costs, if the site is large enough and no hard rock, level than the economy; if space is limited by vertical layout, many occasions it is the only choice. If the site has a solid rock, the rock drill bits can successfully drilled. Connection way with serial and parallel two, in-line system is only one fluid channel, parallel system of fluid in the pipeline can have two or more runners. In-line or parallel connection depends on the size of the cost, in-line system a parallel system of pipe diameter, and the cost of large-diameter pipe. In addition, because the pipe diameter is larger, the system needs a lot of antifreeze, a corresponding increase in weight of the pipe, causing the installation labour costs are large.

★ Plastic pipe options, including materials, pipe diameter, length, circulating fluid head losses. Polyethylene is the geothermal heat exchanger tube materials most commonly used. This pipe of good elasticity, and can be formed by heating than tubes the fusion of its strength and better connection connector. Diameter of choice you have to follow the following two principles: first, the pipe diameter is large enough, circulation pumps for less energy consumption; Secondly: the pipe diameter is small enough so that the tubes of fluid in a turbulent region, make the fluid and the pipe inner wall of the heat exchange efficiency is good. At the same time when the design should also take into account the size of the installed cost.

★ Circulation pump selection. Selection of the circulation pump should be able to meet the continued driving fluid flowing through the heat pump and geothermal heat exchanger, and low power consumption. General in design cycle pump should be able to achieve each ton circulation fluid required power dissipation to 100W.

(4) water source heat pump unit

★ Water source heat pump unit capacity is not too large. Central air conditioner cold heat source equipment selection, equipment cooling (heat) about design cold (hot) load 1.05 ~ 1.10. water source heat pumpunit type, should be as close as possible to the design of cold (hot) load. If set too large, the run time is short, start frequently. Unit capacity, long-running, conducive to dehumidify.

★ Closed water system water temperature, water temperature lower summer requirements, with the aim of improving energy efficiency, reduce power consumption. In winter the water temperature is not too high, because the temperature is high, although high cooling capacity, but also the high power consumption, the efficiency coefficient of variation.

¡Ï design-time objects that you want to consider building heating and air conditioning while using coefficient. At the same time using the coefficient value and building types, and the number of buildings, through theoretical and measured. The residential air-conditioning load calculation using coefficient of lists of data is: when the household page〈 100 households, the coefficient of 0.7; when the number of 100-150 households, 0.65 ~ 0.7; when the number of 150 ~ 200 households when 0.6.

(5) where the chiller unit

Chiller design selection is sure to meet the needs of the cooling load and thermal load, but not too large margin to prevent the waste caused host investment. A system is a good idea to configure two or more host and configure independent cooling water circulation pump, cooling towers and water circulation pump, so you can make the system more reliable, low-load lower power consumption of pump. Since chiller operation no vibration, wear-free, reliable operation, such as the selection of a single host also has an obvious economic advantages without reducing its reliability.

Standard chiller for quantity of heat is the cooling capacity of 80 per cent, that is, if the heat load (such as refrigeration for sanitary hot water, or heating time for hot water or space heating load greater than cooling load), you can choose the high-voltage generator with large capacity, in order to improve the heating or select large cooling capacity unit to achieve (such a large initial investment). Each step of a number of high-voltage generator, heating capacity increased by 20 per cent increase, Q = 0.8 × 0.2. If summer cooling and hot water supply (by summer cooling capacity selection) are: or, and n is the increasing number of high-voltage generator. If the system needs summer refrigeration, winter heating and sanitary hot water supply (fulfill summer cooling capacity requirements checking after the selected models for quantity of heat in winter):

① meet summer and winter seasons usage requirements;

② as heat load in winter, take greater high-voltage generator meets;

③ If heat load in winter, take increasing unit model to meet the requirements (that means a unit increase the cooling capacity models). If you need to increase the unit model meets the requirements, the summer by regulating the burner to keep the economy running. In the transitional seasons system they rely on regulating the burner head to ensure economical operation. In addition, the cooling capacity and the proportion of the quantity of heat can also be used to adjust the implementation of some of the valve.

(6) heat pump unit

★ Unit load selection of air-source heat pump unit is normally based on building the capacity of the choice of the summer cooling load, thermal load in winter to check calculation. If the amount is greater than the unit heating heating load, then the units meet the requirements of winter heating; if the heating load is greater than the unit quantity of heat, you can press the following 2 situation considerations: when a unit quantity of heat heating load of less than or equal to 50% and 60%, you can increase the auxiliary electric heating appliances; whereas it should be considered at the beginning of the investment and operating costs to determine the unit of capacity, that is, the installed capacity of the appropriate increased unit.

¡Ï auxiliary electric heating installed capacity of air-cooled heat pump air conditioning system with auxiliary electric heating devices have the following forms are available: (1) in the fan coil system set small boiler to improve the water temperature in winter unit; (2) in other sources of heat (hot water or waste water), Use the pull-type heat exchanger increase winter water temperature; (3) direct burn (air supply for water, gas, diesel day) to improve the water supply temperature of the heater in winter; (4) with electric heater for improving the water supply temperature in winter.

★ Cool (hot) load in select air source heat pump unit, you should also consider building cool (hot) load. General public buildings, air conditioning equipment are often intermittent operation, that is run during the day, night off, so the day running, since the building's thermal (heat), room temperature needs to run after a certain amount of time to achieve the set value, if shorter this time, the choice of unit, we should consider the accumulation of cold (hot) load. It and cooling (heat) time-related, General cooling (heat) times 2 ~ 3h.

(VII) summarization of combined air conditioner class

At present, the comprehensive functionality of high-rise building of the central air-conditioning system, often to the desired temperature, humidity, ventilation rate, cold (heat) load of air distribution, uses a tiered or partition for centralized processing, its advantages are ease of building property management and use of energy.

Combined air conditioner is a combination of cell function, the user may act according to the air conditioning and air treatment needs, choose the desired sections for free permutations and combinations, have great freedom and flexibility.

Considering the operation and maintenance convenience, air evenly and other factors, should be appropriately set up middle segment.

Selection must note the following points:

1, the manufacturer provides a combined air-conditioning unit features a combination of a paragraph. Map to be given on the selected unit model, specification, section number, feature length, arranged in the order and left-position, and other basic requirements.

2. combined air-conditioning unit operation surface provides for:

(1), back to the fans have one side of the transmission belt;

(2) bag filters capable of handling filter bag side;

(3) automatic winding type filter is equipped with one side of the control box;

(4) cold (hot) media import and export side, the drain side;

(5) washers (above) of water sprinkler fittings.

When people in the face of the unit operations, air blow to the right, on the other hand to right-to-left-style, selection and ordering instructions required for left and right.

3. Select the table coolers, heaters and muffler, you must set the filter (below), to protect the heat exchanger and muffler surface cleanliness to prevent plugging holes, sewing, and should be set in the middle segment.

4, paragraphs, tables, cold water, and so on, apart from the existing sewer received to the air conditioning unit, you should consider the drainage of water plant.

5. choose washer (above), you should note a few level rows.

6. Select the table coolers, heaters (above), should indicate the type and number of rows, use the cold (hot) media properties, such as temperature and pressure. Unit with steam heating, air temperature not less than 20 ° c; to hot water heating, air temperature not less than 15 degrees centigrade.

7. choose dry steam humidifier requires instructions humidification, for steam pressure and controls methods (manual, electric or pneumatic).

8. choose the fan section to illustrate fan models, specifications, installation forms, outlet locations, the fan should be set before the middle segment, ensuring uniform airflow. Air supply unit air enthalpy drop shouldbe not less than 34kJ/kg.

9, indicate the location of the air interface, orientation and size, delivery, return air valve type, specifications, the use of control mode (manual, electric or pneumatic). Blower outlet should have flexible short-tube, fan base should be damper.

10, needs to stay out of the hole and instrument mounting hole locations and the locations of fan power supply lead.

11, unit basis shall take precedence over the Interior of the plane, there should be based around the floor drain, drainage ditch or to exclude the condensation water and the water at the bottom of the venting device.

12, unit around or unit and unit (multiple) layout should be sufficient for the operation and maintenance of space.

13, taking into account the anticorrosion performance unit, Cabinet material best selection of galvanized steel, glass steel or special alloys. For ferrous metals production component surface should be made for anti-corrosion treatment; should be used in fiberglass body oxygen index of not less than 30 of flame retardant resin production.

14, unit standard air leakage rate:

(1) unit within the static pressure to maintain 700Pa, unit air leakage rate is not more than 3%

(2) clean air conditioning system of units within the static pressure to maintain cleanliness 1000Pa, less than 1000 level, unit air leakage rate is not more than 2%; cleanliness level is greater than or equal to 1000, the unit is not greater than the air leakage rate of 1%.

On unit performance appraisal requirements: unit of the air flow, pressure, cooling and heating of the measured value should be greater than or equal to the nominal value of 93% water resistance unit-and the input power of the measured values must not be greater than the nominal value of 110%.

Basic parameter should satisfy the following requirements:

A unit volume measured value not less than 95% of the rated value, full pressure measured value not less than the rated value of 88%.

B unit rated cooling capacity of air enthalpy drop should be not less than 17kJ/kg; air supply unit air enthalpy drop should be not less than 34kJ/kg.

C the amount of air turbine heating temperature at least should not be less than steam heating temperature 20 ° c hot water when heated temperature 15 ° c

Unit in 85% of rated voltage start properly and working.

Unit of the coil and the pipeline in any or all of the following conditions should be long-term normalRun, and no leakage:

A cooling coil in 980kPa pressure, or pass hot water used in 980kPa pressure, 60 ℃ hot conditions;

B hot water coil in 980kPa pressure, 130 ° c under the conditions of hot water;

C steam coil in 70kPa pressure, 112 ° c for steam conditions.

Unit inside the insulation, acoustic materials with non-toxic, no smell, self-extinguishing and non-absorbent performance. You should not use bare asbestos or fiberglass material. Insulation, acoustic materials and panels should be strong, smooth, seamless, out-of-the box at run time without condensation on the surface.

Condensate water treatment unit should be set, outside of the box in the run should not be leaking water, there should not be stagnant water in the tank, drainage should be smooth.

Box and check the door should have good air tightness, air leakage rate of less than 5% be-check locking performance is much better to prevent internal and external pressure differential switch itself. Coil face the wind, the wind speed exceeds 2.5m/s should be retrofitted retaining plate. Water jet segment into, out of the wind side should have excellent water board.

Unit box should have adequate stiffness, running should not be deformation. Units using ferrous material, the surface should be treated with preservatives.

Summary of chapter III of the auxiliary equipment selection

First, the water pump class product selection guide:

1. Select clear water pump mainly see parameter flow and head;

2 centrifugal pump is suitable for large-volume, large-head of the establishment;

3, pipeline pump flow range is not large, applies to lift low places.

4. regular select horizontal pump, when the installation has limitations when selected vertical pump;

5. when the single-stage pump does not meet the requirements for select double-stage pumps;

6. when the temperature of 65 ° c, t > hot water pump is selected; when t ≤ 65 ° c, cold water pump.

Second, the new fan equipment selection steps are as follows:

1, according to the installation settings to select new fan;

2. the device air flow, pressure when you choose to not less than the design value is in principle;

For special industries, such as hospital (operating room, intensive care Wo Ward), laboratory, workshop, according to the instruments industry related regulations identify needed new air flow.

3. determine the amount of refrigeration and heating design operating conditions;

4. in principle, a fresh air handling units only a floor of new air volume required;

Third, fan-coil equipment selection steps are as follows:

1. clear the selection of unit type, specifications, diffusers, and so on.

In the selection of fan coil unit refrigeration units, is to design warm-up load and thermal load unit display. In most cases, coil have sufficient latent heat capacity, can meet the design requirements. If using outdoor air is appropriate dressing their load and calculation formula: water temperature rise (° c) = air temperature rise (° c, db)

First to determine the work requirements:

Refrigeration: indoor warming refrigeration load (), the total heat indoor cooling load (), the air temperature (° c, db/℃ wb), the water temperature (° c), the amount of wind ();

Heating: usually chosen by the refrigeration unit, heating capacity is adequate, receipt of same by water flow to selected. That is, with water temperature for indoor heating load required. Indoor heating load (), the air temperature (° c).

Then determine the unit specifications, the required water quantity, water temperature and pressure drop, and other parameters.

2, clear the selection of the unit of water left out or closing out a direction (and related piping layout etc).

3. clear fan motor bearings is used for oily or not oily axis pump. If you choose not to use the oil axis pump, consistently within regular refueling.

4, notice the water of the thermal insulation measures so as to avoid the summer use of condensation, defaced indoor building.

5, hot water, water temperature in winter pass normally does not exceed 60 ° c, could reduce scaling of alternating hot and cold while mitigating role expanding lhe forces weakened, affecting heat transfer.

6, unit coil set the highest operable.

IV. Summary of cold water tower

1, according to the cooling water temperature: temperature in high-temperature Tower, Tower, Tower.

2. follow the installation location of the current situation and the requirements for noise: crossflow Tower and countercurrent Tower.

3. follow the chiller cooling water cooling water selection, in principle, slightly larger than the cooling tower water chiller for cooling water.

4. selection of multiple water tower to select the same model.

Secondly, the cooling tower selection need attention:

1, Tower body structure material to stability, durability, corrosion resistance, assembled with precision.

2, water allocation uniformity and Wall flow less splattering device selection is reasonable, is not easy to stop up.

3. spray fillers of the type conforms to the requirements for water quality, water temperature.

Match 4, fan, to guarantee long-term uptime, no abnormal noise and vibration, and leaves with good resistance to water erosion and is of sufficient strength. Fan blade installation angle adjustable angle to ensure consistent and motor current not exceeding the rated current of the motor.

5. low power consumption, low cost, small and medium-sized steel framed glass Tower also calls for the quality of light.

6, Tower should try to avoid the heat source, exhaust and flue gas occurs at the point, chemicals and coal pile piled nearby.

7, cooling tower or tower and the distance between other buildings, apart from considering the requirements of ventilation Tower, Tower and building mutual influence, you should consider building fire, explosion-proof safety distance and the construction and maintenance of cooling towers.

8, cooling tower of fles direction by 90 °, 180 °, 270 ° rotation.

9, cooling tower of the material is resistant to low temperatures-50 ° c, but the average temperature for the coldest month is less than-10 ° c in the region should indicate when ordering in order to take measures to prevent icing. Increase in the cost of cooling tower is about 3%.

10, the cycle of water turbidity is not greater than 50mg/l, short-term 100mg/l is not greater than not contain oil and mechanical impurities, if necessary, take out the algae and water stabilization measures.

11. water distribution system is designed for nominal amount, such as the actual difference between the water and the nominal quantity of ± 15%, when ordering should indicate to modify the design.

12, cooling tower parts in storage during transport, it shall not be pressing weights, and attention to fire exposure. Cooling tower and installation, transportation, repair process must not use electricity, gas welding, flame, no use of firecrackers in the vicinity of the fireworks.

More than 13, round tower, Tower and Tower design between net distance should remain less than 0.5 times Tower body diameter. Countercurrent flow cooling tower and the square Tower can be side-by-side layout.

14, selection of the pump should be equipped to ensure the flow of cooling tower, lift and process requirements.

15, when you select multiple cooling towers, use the same model as possible.

In addition, measure the effectiveness of the cooling tower is usually also adopts three indicators:

(1) cooling tower water inlet temperature and outlet temperature t1 t2 difference Δ Δ t t, is known as the cooling water temperature, in General, the higher the temperature, the cooling effect is better. In terms of production, the greater the Δ t production equipment cooling water flow rate can be reduced. But if the water temperature t1 is high, even if the temperature difference between Δ t, cooling water temperature may not be reduced to meet the requirements, so this indicator is needed, but the description of the problem is not comprehensive enough.

(2) cooling water temperature t2 and air wet-bulb temperature ξ proximity Δ Δ t ', t ' = t2-ξ (° c), Δ t ' called cooling high. Δ t ' value is smaller, the better the cooling effect. In fact Δ t ' could not be equal to zero.

(3) into account in the calculation of the cooling towers of tricking water density. Tricking water density refers to the effective area of 1m2 every hour on the cooling water. Q with symbols. Q = Q/F, m3/m2.h (Q-cooling flow, m3/h; effective F-cooling tower water spray area, m2)

Other notes:

1. in accordance with the conditions and amount of water to determine its main parameters.

2. optimization for efficient (the same water body machine small).

3. optimization of low noise (the same water fan input power low noise low).

4. packing material good long life, flame-resistant packing optimization for first.

5. selection location consideration should be given effect by the monsoon.

Requirements:

1, the resistance of pipe cannot be lower than fill pipe inlet diameter.

2, cooling tower water pipe valve closer from the Tower, the better.

3. recommends that the return pipe insulation outdoor part.

4, multiple parallel cooling recommendations made two road, waterway, easy to adjust in units of energy-saving operation.

5, cooling tower startup must first open water pump, after the fan. Not allowed in the absence of rain water is fan operation.

Therefore, in the water pipe is equipped with a tilt of the water board, if you start the fan without water, the water distributor flip, water boards will scrape to packing, packing away by the wind blowing out or cloth water card bad, cooling tower starts, we must first open water pump, blower, open back stopped working, first stop after stop water pump, blower.

5. air inlet product selection guide

1. first, according to technological requirements and field conditions, etc., determine the form and sent back to the wind, air distribution and air outlet type;

2. Secondly, according to the air flow to determine the dimension of the diffusers;

3. once again, the selection is also note the following requirements:

(1) General use louver or slit air outlets, and other side sent, conditional, should be affixed to the side to send air flow. Process air conditioning room, when the room temperature permitted fluctuation range is less than or equal to ± 0.5 ℃, the air should stick to the side to send.

(2) when there is a ceiling available, according to the room height as well as the use of the site on the air, using circular, square and gap type diffuser and orifice plate air. When the unit area air is big, and workspace called wind smaller or regional temperature requirements strictly, should adopt the orifice plate air.

(3) space for a large public building and room temperature permitted fluctuation range is greater than or equal to ± 1.0 ¡æ tall plant, use vents or swirl diffuser air.

Used to attach the side sent, should meetthe following requirements:

(1) air distance from the ceiling on the edge of the large, air services should be set up 10-20 degrees centigrade of diversion.

(2) air should be set so that the Jet is not about skewed to the Distributor.

(3) there shall be no Jet process stops. In addition, air export wind speed, air distribution, air type, installation height, Interior allows wind speed and noise standards, and other factors. Muffler requirement is high, suitable for mining2-5m/s, vent air can take 4-10m/s.

Back to the arrangement of diffusers, should meet the following requirements:

(1) back on the air outlet should not be located in the Jet area and who stay for a long time, the use of the site, the side to send in the air of yishe with side.

(2) where applicable, may be set back to the wind or corridor air return, but Corridor section wind speed should not be too large.

Weak current College】【HVAC professional English table (4).

Refrigeration
The first section of general terms
Section 6.1.1 of refrigeration refrigeration
Artificial methods from a substance or a space out of the heat for the air-conditioning, refrigeration and scientific research and so provide cold source technology.

Section 6.1.2, refrigeration engineering refrigeratingengineering
Refrigerator and its main equipment and system design, manufacture, application and action technology.

Section 6.1.3, cooling capacity refrigeratingeffect
Unit of time, from the refrigerator evaporator of refrigerant out of the heat.

Section 6.1.4 bar standard refrigeration capacity standardrating [ofrefrig-ratingmachine]
p>
Section 6.1.5 of air conditioning load cooling capacity ratingunderairconditioningcondition
The working conditions of air conditioning, refrigerator cooling capacity.

The first section 6.1.6 condensingpressure condensing pressure

Refrigerants condensing pressure.

Section 6.1.7 articles condensing temperature condenoingtemperature

The refrigerant vapor condensation in the condenser, correspond to the condensing pressure saturation temperature.

The first article 6.1.8 evaporatingpressure evaporation pressure

Refrigerant liquid in the evaporator evaporation pressure.

Section 6.1.9 evaporatingtemperature article evaporation temperature

Refrigerant liquid in the evaporator in gasification, corresponds to the evaporation pressure of the saturated temperature.

The first article 6.1.10 suctionpressure inspiratory pressure

Compressor inlet suction tube refrigerant gas pressure.

The first article suction temperature suctiontemperature 6.1.11

Compressor inlet suction tube refrigerant gas temperature.

Article 6.1.12 bars gas pressure dischargepressure

Compressor outlet exhaust tube refrigerant gas pressure.

The first section exhaust temperature dischargetemperature 6.1.13

Compressor exit of the exhaust pipe to the temperature of the refrigerant gases.

The standard conditions article 6.1.14 standardcondition

Comply with the standards stipulated in the refrigerator running conditions.

The first article 6.1.15 airconditioningcondition air-conditioning operation

In order to meet the air conditioning requirements stipulated in the refrigerator running conditions.

Article 6.1.16 [chiller] [refrigerating] coefficient of performance (COP) coefficientofperformance

In the specify conditions, refrigerator cooling capacity and its ratio of net input of energy.

The first article cold-water chilledwater 6.1.17

A refrigeration system out of the cold-temperature water or natural water.

The first section of the cooling water coolingwater 6.1.18

Refrigeration equipment for cooling water.

The first article enthalpy enthalpy 6.1.19

Substances with a thermodynamic properties. Defined as the material product of the volume, pressure, and can be combined.

The entropy of entropy 6.1.20

A thermodynamic State functions. For a State by State 1 to 2 of reversible processes in a closed system, with its changing value to the given points. Dq represents the temperature of which is t, system and environment to exchange heat between reversible base units.

The exergy exergy 6.1.21 bar

Energy may be converted to the long hard parts.

The first section fire no anergy 6.1.22

Energy cannot be converted into useful work.

The article-enthalpy diagram 6.1.23 pressureenthalpychart

To pressure and enthalpy value coordinates representing material status changes of thermal state diagram.

The first article enthalpy entropy diagram 6.1.24 enthalpyentropychart

The enthalpy, the entropy for coordinates and represents the physical status of thermodynamic state diagram.

The first section press junto 6.1.25 pressurevolumechart

To pressure and conformity coordinates representing the ratio of material status changes of thermal state diagram.

The first article refrigeration room refrigeratingstation 6.1.26; refrigeratingplantroom

Install the refrigerator and, its by-laws, in the case of devices in the room, also called the freezing point.

HVAC professional English table (5)
The second section of refrigerants and refrigeration cycle

Section 6.2.1 of refrigerants workingsubstance

In working in a thermodynamic cycle.

Section 6.2.2Article refrigerant refrigerant

Refrigeration system, the completion of the work of the refrigeration cycle.

Section 6.2.3 of azeotropic refrigerant azeotropicmixturerefrigerant solution

Two or more of the refrigerant, according to certain component mutually dissolved generated mixed refrigerant. In the constant pressure of the refrigerant has a constant temperature of evaporation and condensation temperature, gas and liquid phase with the same component.

Section 6.2.4 non-azeotropic refrigerant nonazeotropicmixturerefrigerant solution

Two or more of the refrigerant, according to certain component mutually dissolved generated mixed refrigerant. In the constant pressure of the refrigerant evaporating temperature and condensing temperature does not remain constant, and gas and the liquid has the same composition.

≫ section 6.2.5 of freon freon

Used as refrigerant in saturated hydrocarbons halogen derivatives of hydrocarbons.

≫ section 6.2.6 of ammonia and ammonia

A molecular formula for NH3 of inorganic compounds refrigerant.

≫ section 6.2.7 of LIBR lithiumbromide

Absorption refrigeration of the absorbent. A formula for the solid salt crystal LiBr.

≫ section 6.2.8 article refrigerant water waterasrefrigerant

In absorption refrigeration, water as refrigerant.

≫ section 6.2.9 of refrigerant secondaryrefrigerant; refrigeratingmedium
Indirect refrigeration system to absorb the refrigeration space or medium heat and transfer it to a fluid refrigerant, also known as refrigerant.

≫ section 6.2.10 strongsolution article concentrated solutions; strongliquor

Solute composition higher solution.

Section 6.2.11 of dilute solution weaksolution

Solute composition lower solution.

Section 6.2.12 Strip anticorrosive corrosionsnhibitor inhibitor;

Join the liquid to lower the freezing point of an additive.

The first article antifreeze antifreezeagent 6.2.13; antifreezer

Join the liquid to lower the freezing point of an additive.

The first section 6.2.14 flashgas Flash gas

Liquid refrigerant because of sudden depressurization of partial evaporation gas.

Section 6.2.15 bar Non-Condensable gases noncondensablegas; foulgas

In condensing temperature and pressure, no condensation and exist in the gas in the refrigeration system.

The thermodynamic cycle thermodynamiccycle 6.2.16 bar

Refrigerant thermal change over again to the initial state of a series of thermal process.

Section 6.2.17 bar cyclic reversiblecycle

Consists of a series of reversible processes consisting of ideal thermodynamic cycle.

The Carnot cycle Carnotcycle section 6.2.18

Includes two isothermal process and two adiabatic process will maximize thermal energy into mechanical energy in an ideal reversible loop.

The first section 6.2.19 reverseCarnotcycle reverse Carnot cycle

And the Carnot cycle is the same as the opposite of the loop.

The refrigeration cycle refrigeratingcycle 6.2.20 bar

The refrigerant in the refrigeration system experienced a series of thermal process consisting of the thermodynamic cycle.

Section no. 6.2.21 compression refrigeration cycle compression-typerefrigerationcycle

By refrigerant liquid gas, vapour compression, vapour of machinery of liquefaction and liquid expansion, four segments of refrigeration cycle.

The first article compression compression 6.2.22

Compression refrigeration system, upgrade the refrigerant pressure process.

The expansion of expansive 6.2.23

The fluid pressure reduction, enlargement process.

The first rule 6.2.24 throttlingexpansion throttle expansion

Refrigerant through any expansion hypotensive components. With the outside world without mechanical power delivery.

The first article condensation condensation 6.2.25

Gaseous refrigerant through the process of cooling becomes a liquid.

The first article supercooled subcooling 6.2.26

Liquid refrigerant temperature down to the appropriate pressure condensation temperature following phenomenon.

Section no. 6.2.27 undercooling degreeofsubcooling

Condensing temperature and cold temperatures.

The first article overheating supeheat 6.2.28

Gaseous refrigerant pressure temperature rise to a correspondingOf the phenomenon of saturated temperature above.

The first article superheat degreeofsuperheat 6.2.29

Overheating temperature and the difference between saturated temperature.

The 6.2.30 article absorption refrigeration cycle absorptionrefrigerationcycle

Powered by the heat from the refrigerant gas, vapour absorbed liquid absorption, heat absorption liquid refrigerant vapour out and refrigerants condensing, expansion, and other processes of refrigeration cycle.

The vapour blasting 6.2.31 of refrigeration cycle steamjetrefrig-erationcycle

Use of Jet will refrigerants ejection from the evaporator, condenser to make the process of completing the cycle of refrigerants.

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