Weak current College】 【intelligent central air conditioning energy saving measures and principles.

<br> Author: Hui hua Xiong <br> Summary: my school will be construction of small intelligent central air conditioning laboratory works, for example, on this kind of building energy-saving measures and the principle that compares several common heat recovery equipment performance ., pointed out that the current design and application of the air conditioning system lags, central air conditioning energy saving measures and significance. <br> Keywords: intelligent central air conditioning energy saving measures principle <br> 1. intelligent central air conditioning energy saving significant .<br> Air conditioning is the intelligent buildings to create a comfortable and efficient working and living environment is an indispensable part. In the intelligent construction, the HVAC systems monitoring point number often account for floor control point more than 50% of the total; HVAC .systems in consumption, often representing building total electricity consumption of more than 50%. This shows that the HVAC systems in intelligent building one investment and running costs in occupies a very important position. <br> In many buildings, or in the building's construction phase ., the BMS (building management system) itself often is the intelligent building management system (IBMS)-led components, and HVAC systems control section and a BAS or BMS systems-led components; for this type of building, HVAC control system is important position .. <br> In the intelligent construction-saving energy-saving in implementation, especially the large power dissipation-the power-saving energy-saving air-conditioning system implementation, this should be the owners of the investment of computer control (also even if .the building has an "intelligent") can look forward to one of the main content of return; however, at present in the construction of intelligent building, really it is a rarity. In other words, only a handful of intelligent buildings (one! .) for saving energy, the majority has not achieved the intelligent building energy-saving energy-saving this one should realize the return. Now we are imagining this article to explore the intelligent energy-saving air conditioning of in. <br> 1.1 air- .conditioning and the operation of the control system is far from ideal <br> According to the survey: user on building automatic control system operation of the evaluation are: satisfactory only 30% and 40% in General, the poor have accounted for 30%. .The survey found that apart from a few buildings technology advanced, the movement is good, generally there is a wide variety of issues: the technology is not advanced, there are serious shortcomings in the operation of, and some can not be opened. <br .> Having invested design and installation of computer control system, if it cannot be opened, or at run time because of this or that failure is removed, this cannot be said to be a serious lesson, interested parties should address the issues, carefully analyze the .reasons and to take effective measures to prevent recurrence. <br> It should be noted that the air conditioning and control the system is running in the problems are not unique to our country. A United Kingdom experts, BuildingEnergyManagementSystems (building energy management system), .the author of the book in his writings of gjlevermore foreword wrote: "I do often ask designers, users, and students, if they know any buildings in a debug run good after, but the answer is extremely scarce. I hope that my book .will help alleviate such problems. "The intelligent construction, as a result of rapid development, and market management and technology management and the existence of some degree of confusion, so the problems exposed is broader, deeper and more serious. <br> 1.2 air .-conditioning automatic control design and air-conditioning design lags <br> In intelligent central air conditioner, the automatic control system for the implementation of the project, now largely through the following projects: the construction design Institute of HVAC design professionals, and air conditioning .air-conditioning automatic control requirements, and Design Institute of automation professionals air-conditioning automatic control design, by automatic control equipment manufacturers to control part of programme design and construction drawing design, and automatic control equipment manufacturers to control part of the installation, and then .transferred to the property management Department for operational management. In the engineering process, involving units including enclosed design Institute, civil construction, equipment installation, automatic control manufacturer, etc., of course, there are decisions and control role owners. This should form a .closely cooperate with a ring for a ring, smooth operation of the chain, however, practice shows that all important links often lags, legacy in the future, and to the building automation system uptime and energy-saving effect have serious problems. Often manifested in .synch: <br> (1) Design Institute HVAC professionals on the automation requirements of professional references are often not enough depth; <br> (2) device mounted units of equipment installation work is not carried out according to the statutes, after installation is .complete on all air supply system and water system is not a serious test and balance; <br> (3) automatic control equipment suppliers, often in the bidding, "what work can do"; but in the implementation of the project, or lack .the necessary expertise, or engineering scale, thus unable to carry out specific projects, often with a detailed analysis of some "copy" to stuff even without the digestion to cope with the project. Automatic control equipment manufacturer commissioning work are generally not available: for .example, for building characteristics and specific network features some of the parameters select the rough, summer, winter and excessive seasons different air condition generally is not sufficient for debugging, and so on. <br> 1.3 design system to be adjusted <br> HVAC .system design of the automatic control system, particularly the HVAC system design for computer control system is built on the system on the basis of the daily operation, that is, in essence, is a non-steady state and dynamic design. Computer control system requires .dynamic analysis of data, and HVAC design provides limited steady state data-this is the current construction of intelligent building, HVAC system design and HVAC control system design lags. <br> 2. central air conditioning system generally constitute <br> Central air conditioning .system mainly consists of the following: <br> 2.1 frozen host and cooling towers <br> Host a, frozen <br> Frozen host is also called cooling PackReset is caused by the "central air conditioner cold sources", leading to various sections of .the circulating water from freezing host "internal heat", the cooling water to "freeze." <br> In recent years, there are also frozen host adopts frequency conversion speed is determined by production factory of his first wife, without modification. Not adopt .the frequency conversion, transformation of frozen host as examples of variable speed is not more. <br> B, cooling towers <br> Frozen host in the cooling process, will release the heat so that heat units. Cooling water tower used to freeze the .host with "cool water". Cooling water flow through the swirling, frozen after the host will take away the frozen host, host the frozen calories. <br> 2.2 "external heat" system <br> A £ ® frozen water circulation system < .br> By frozen pump and chilled water piping. From frozen hosts out of the frozen water pressure by frozen pump into chilled water piping, through the coil in each room, take the heat in the room, the room temperature decrease. At the same time ., the room was freezing water absorption of heat, the temperature of the chilled water. Temperature rise of circulation in the Netherlands after freezing host became frozen water, so the cycle. <br> The outflow from the frozen host, enter the room of frozen .water referred to as "water", flows through all the rooms of the host back to freeze freezing water referred to as the "return". No doubt return water temperature will be higher than the water temperature formation temperature difference. <br> B £ .® cooling water circulation system <br> Cooling pumps, cooling water and cooling tower. Frozen host in the heat, the cooling water temperature, will release a large amount of heat. The heat absorbed by the cooling water, cooling water temperature rise. Cooling .pump will rise the temperature of cooling water in the cooling tower, the tower and the atmosphere to heat, and cooling in the cooling water, sent back to the refrigeration unit. So loop took frozen host release heat. <br> Flow into the frozen .host cooling water referred to as "water", from frozen host flow back to the cooling water cooling tower known as "water". Similarly, the return water temperature will be higher than the temperature of inlet temperature formation. <br> C £ ® .cooling fan has two conditions: <br> Coil Fan installed in all the required cooling room, for consisting of frozen water cooled cooler air blown into the room, to speed up the heat in the room. <br> Cooling fan is used to reduce .the water temperature was Tower, acceleration will "return" to bring back the heat to the atmosphere. <br> You can see, central air conditioning system in the working process is a continuous heat energy conversion process. Here, chilled water and cooling water .circulation system is a major energy carriers. Therefore, on frozen water and cooling water circulation system of control is central air-conditioning control system. <br> We present the graduation-sized intelligent central air conditioner is also broadly in line with this, there .are two sets of central air conditioning system, consisting of three cooling water pumps, three frozen water pump, two cooling fans, two chillers and other main components of two sets of refrigeration system, which is composed of chiller equipment manufacturers supply. According to the .current design of laboratory requirements, we chose 2 * 5 horses all closed compressor chillers. It is based on the principles and rules of the air conditioning, automatic control by the microprocessor. Chiller by compressor, condenser and evaporator. Compressor compresses the refrigerant, compressed .refrigerant into the condenser, the cooling water cooling, a liquid, sludge thermal take away from the cooling water and cooling tower was discharged into the atmosphere. Liquid refrigerant by the condenser into the evaporator, the heat of evaporation absorption chiller to cool down, and .then frozen water into the cooler coil absorption of heat in the air. <br> 3. frequency of functions <br> 3.1 frequency function <br> Fan and pump are transfer fluid equipment, this type of load consumption of energy and flow is proportional .to the cube, the calculation of available energy consumption and speed, specific relational expression: <br> That is, Q = K1n; H = K2n2; P = Q × H = K1K2n2 = K3n3 <br> Type, K is a constant and .n is the motor speed. <br> Also: three-phase AC induction motor rotational speed n = 120 × f × (1-s) / p, type power supply frequency f is in, s-slip, p is the number of .motor pole. <br> Motor once selected, the basic S, P, n can be approximated as n = k0f, ie the power supply frequency is linearly. <br> When the frequency is 50 Hz, n = k0 × 50 rotation / .min; power P1 = K (k0 × 50); when the frequency is 45Hz, n = k0 × 45 rpm, power P2 = K (k0 × 45). <br> P1 = P2 / K (k0 × 45) / K .(k0 × 50) x 100% = 72.9%, we can see that when the power supply frequency from 50Hz downgraded to 45Hz, you can save energy up to 27.1%. <br> When using the valve to open degree to control water, .pipe resistance curve and drag the bezel power p changes (Figure 1). From curves 1 and 2 curves, reduced water and how much power did not decrease. But by changing the speed n to adjust air volume is a different matter. <br> .Adjust the speed of the curve when HQ curve 1 to curve 2, valve to open degree 100% tube resistance curve unchanged, and power savings. Where n1 to adjust the speed before, after adjusting for n2 speed. <br> 3.2 soft-start .function <br> Because the motor voltage is started, the unloaded start current equal to (3-7) times the rated current, therefore usually load motor starts, the power supply to the motor and power have serious impact, leading to excessive network capacity .requirements, and start on the heavy current equipment and vibration on device extremely unfavorable; and start-up and shutdown, water hammer effect (hydraulic hammer), it is easy to result pipeline rupture, the use of frequency converters, soft-start feature will .start current far lower than the rated current for motor in the true sense of the soft start. Not only reduces power and network impact, and can extend equipment life and reduce the setKeep maintenance costs. <br> 3.3 cooling water system of frequency control < .br> The above projections, you get a qualitative concept. In other words, for a traditional air conditioning system, air conditioning equipment are design project-matching, the vast majority of time the device is operating at low load situation, so wasted effort, .consumed a large part of energy. If the inverter for variable speed drive, you may only need to this time motor 45Hz speed operation to meet the requirements of the entire system of temperature control. According to the above theoretical projections, actual energy conservation can be .as high as 27.1%. Thus, in a fan pump mechanical, frequency inverter speed control to adjust the volume or flow, saving is a valid method. <br> 4. energy-saving methods and measures of other <br> 4.1 strengthening design .staff management, speed up the implementation of equipment the engineer registration system <br> HVAC engineering projects, there should be more detailed and cooling load and thermal load calculation and these energy-saving measures, many designers are these energy-saving measures, and are .essentially used indexes, estimates that cold again, the heat source host long in low-load, low efficiency. <br> 4.2 HVAC indoor temperature determination <br> The Chongqing, Shanghai, Guangzhou and other areas of practice has proved that the room temperature .to reduce summer 1 ° c or 1 ° c in winter to rise, with the exception of HVAC works of the investment increased by 6% to 8%, greatly increase the indoor and outdoor temperature difference would not be in keeping with the hygiene requirements. .Comfort air conditioning in summer ideal indoor temperature is lower than the outdoor temperature 5-8 ° c as well. <br> 4.3 air-conditioning heat and cold sources <br> Central air conditioning energy consumption generally consists of three parts, namely, ( .1) heat source; (2) air conditioning unit Terminal is located; (3) water or air transportation system. This three-part, heat and cold sources in energy consumption energy consumption accounted for about half of the total energy consumption is an important .element of energy-saving air conditioner. If you are putting their consumption of energy is converted into an energy source, the various units are available once per time unit energy consumption by energy production of cold or heat, this article uses a primary energy efficiency OEER .(W / W). <br> Units from the energy point of view summer refrigeration: centrifugal and screw chiller OEER value maximum, steam twice LiBr absorption chiller OEER minimum; winter heating: screw, piston-type heat pump chiller OEER highest, the .lowest electric hot water unit, ie the highest energy consumption. <br> 4.4 air-conditioning unit and terminal equipment <br> In 1997, statistics, domestic production air blower plate Tube manufacturers have 200 of annual capacity is 60-80 million units; .the air conditioning unit there are more than 100, yield of around 5 million units. <br> 4.4.1 the air conditioning unit <br> You should choose the unit's fan, air pressure, air leak less matches, the number of air transportation .system to teach large unit. <br> 4.4.2 air blower plate Tube <br> Fan-coil and from looking at the overall level of similar foreign products compared to the same, but the comparison with foreign advanced level, the main difference is .the power consumption, coil weight and noise. <br> 4.4.3 air-conditioning system <br> General air conditioning water system of transmission and distribution of electricity, heating in winter period accounted for the entire building dynamic power of 20-25% .; in summer cooling period accounted for about 12-24%, designers should pay attention to the water system design, actively promote variable speed pump, winter and summer dual-speed pumps and other energy-saving measures. Therefore energy-saving water system. .<br> (1) select the pump is the design value find pump sample nameplate parameter, instead of by the pump performance curve selected pump models; <br> (2) not to carry out each water loops, hydraulic equilibrium calculation for pressure differential .vastly loop end also take effective measures, hydraulic, misadjustment phenomenon seriously; <br> (3) large capacity, small temperature difference widespread, design temperature for, backwater from 5 ° c, in general but through measured, summer chilled water temperature better backwater .to 3 ° c, poor only 1-1.5 ° c, resulting in the actual flow of water over the design of large 1.5 times so that the water pump power consumption increased significantly. <br> 4.4.4 cooling tower <br> Refrigeration systems .-cooling water inlet temperature and low power consumption to host has an important impact on general projection, the water must have a water temperature of 1 ° c, power consumption electric compression host about increase of 2%, lithium bromide water chiller energy high 6% .. <br> At present there are mainly domestic GFRP cooling tower is as follows: <br> (1) cooling efficiency low, up to a sample of the product provides cold sites. <br> (2) bleach water seriously, it not .only pollute the environment, and waste water. <br> (3) noise, noise surrounding residents living environment. <br> Therefore, from the energy point of view, we should try to avoid using homemade GFRP cooling tower. <br> 4.5 .strengthening central air conditioning management <br> 4.5.1 strengthening air-conditioning operations personnel training, to improve management quality, air operators operating permit system. <br> 4.5.2 central air conditioning system independent power consumption (can) accounting system. Overcome .the power to eat "communal pot", to be a waste of electricity (energy) penalty, saving electricity (energy) award system. <br> In addition to the above points, according to the specific project situation. Active promotion of water- .loop heat pumps, heat recovery, VAV, vwv and other energy-saving technology <br> 5. concluding remarks <br> About intelligent central air conditioning energy saving issues, some of the previous project, the design parties tend to design of energy- .saving compared to the other condition is entirely relying on automatic control system or supposes more manual control valve, in fact, a lot of energy saving space in the non-design conditions. To achieve energy-saving design at first, so that the system meets .the design cycle, should, as far as possible more research to make system design as much as possible close to the actual situation in year-round operation, and management in their day-to-day work should be fully informed of all devices in the .system and part of the function and role, and positive flexibility in application.If the parties together to save energy is not difficult to solve. <br> Reference documents <br> 1. the central air conditioning engineering design and construction of Wu Zhou Jihong .Mr Dannis Lee Jor authoring / publishing house higher education <br> 2. the refrigeration and air-conditioning automatic control of Zhang Zi Hui-Haefel/science press <br> 3. the fluid pipeline on pay-Chiu Wang Yue man Wang Yuan Liang ., authoring / publishing house of China construction industry <br> 4. the air-conditioning and refrigeration technology guide Chan Pui-lam, Yue filial million editor-in-Chief/Tongji University Publishing House <br> 5. the central air-conditioning .equipment selection guide week Bong Ning editor-in-Chief/China construction industry press <br> 6. 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