Weak current College】 【the air conditioning with cooling technology law questions and answers reference 18 --- Power By】 【China power house network.

<br> Question <br> 5, the first law of thermodynamics, the second law of thermodynamics research what is the significance? <br> A: the first law of thermodynamics is energy conversion and conservation laws in specific thermodynamic process, applied to the .determination of the thermal system and external exchange energy energy equation; the second indicates the nature of Thermodynamics of spontaneous process has a certain direction and irreversibility, non-spontaneous process of implementation must be able to add conditions to solve thermal power conversion conditions, direction and .limits. Therefore, thermodynamics, the second law is the theoretical basis of thermodynamic studies. <br> 6, there are two kinds of fluid flow pattern of discrimination flowing? criterion? <br> A: the two fluid flow mainly Laminar and turbulent flow .in two ways. Discriminant criterion of Fluidization is fluid, the Reynolds number Re <br> Re. 2000 for laminar, Re> 2000 to turbulence. <br> 7, reducing the flow resistance of measures are those? <br> A: .to reduce the flow resistance of the main ways of improving the side wall on flows, measures including reduced frictional resistance (reduce wall roughness and adopt flexible wall), and to reduce local resistance (make the fluid inlet to ride with expanded and reductive instead of .circulation section suddenly expanded and out, reduce the turn, the deal tee structure layout, reasonable convergence and arrangement of the pipe, pumps or fans, shorten pipeline, etc.). <br> 8, what are the basic methods of heat transfer? .all in what circumstances? <br> A: there are thermal conductivity, heat transfer by convection and radiation heat transfer in three fundamental ways. Heat conduction to occur on the same object the internal temperature is different between the parts or in direct contact with the .temperature difference between thermal transfer objects; convection occurs in fluid and solid wall of the heat transfer between; radiation heat transfer is due to the heat because (own temperature or micro-particles by thermal movement) and objects inspired to outside radiation of electromagnetic waves between .the object and the absorption of heat radiation from each other's total effect. <br> 9, and as heat transfer equation? how to make heat transfer enhancement and weaken? <br> For heat transfer equation for; Q = KA (t1-t2 .). Under heat transfer equation, improve heat transfer coefficient K, extending A heat transfer surface area, increasing the heat temperature difference Δ t can increase the transmission of heat, but declined. Enhanced heat transfer measures: reasonable expansion heat transfer area. Increase temperature ., increasing the heat transfer fluid velocity, remove dirt reduces thermal resistance: weaken measures heat; laying of insulation, reducing heat transfer fluid velocity, changes the surface condition (eg, plus cover hot plate), etc. <br> 10. outline the .nature of the freon refrigerants and application range. <br> A: the freon is saturated hydrocarbons in the all or part of the hydrogen elements are halogen element fluorine, chlorine, bromine substituted after derivatives. Freon refrigerant broad term refrigerator and air-conditioner and .other refrigeration and air-conditioning equipment. <br> 11, vapour compression refrigeration uses refrigerants limbs is how to categorize? <br> A: according to the chemical structure: ① inorganic compounds (such as R717, etc.); ② freon ( .R22, R134a, etc.); ③ multivariate mixed solution (non-azeotropic solution with R407C, azeotropic solution with R502, etc.); ④ hydrocarbons (R600a, R290, etc.). By evaporation temperature and condensation pressure points are: ① .② high temperature and low pressure refrigerant; Middle temperature and middle pressure refrigerant; ③-temperature high-pressure refrigerants. As you can so sexual and toxicity, Division is not so, so, flammable, low toxicity, a combination of high toxicity, etc .. <br> 12. What is a CFC substances? why do you want to restrict and disable CFC substances? <br> A: the CFC substances is not hydrogen of freon. CFC substances on air-ozone and ozone layer of the Earth's upper .air has serious damage, causes the Earth's surface UV radiation intensity increases, the destruction of the body's immune system. Also cause atmospheric temperatures, increased the greenhouse effect. Therefore, reducing and disable CFC type of substance use and production, has become the international social .and environmental protection of urgent tasks. <br> 13, refrigerant do? on refrigerant nature of those basic requirements? <br> A: the refrigerant's role is to be indirect cooling body transport refrigeration system produces cold. On refrigerant properties of the basic requirements .are: refrigerant heat and wear of the coefficient to big, viscosity and density, low freezing point to, volatile and corrosion suction to smaller, non-toxic odorless, harmless to the human body, chemically stable, inexpensive, easy to access. <br .> 14, refrigeration oil functions those? <br> A: refrigeration oil lubrication of the functions are: to reduce the friction surface; cooling parts wear, friction parts; reducing compressor power bees friction surface gap, stop refrigerant leakage; scouring friction surface. .Keep away debris; the use of lubricating oil pressure control system to uninstall. <br> 15, supercooling refrigerant throttle on tidy before compression refrigeration cycle nuclear? in practice may use those methods implement throttling supercooling refrigerant before? <br> A: throttle supercooling .refrigerant before will improve quality refrigeration capacity and power consumption of the compressor will remain basically unchanged, thus improving the refrigeration cycle refrigerating factor, supercooling refrigerant throttle ago also facilitates expansion valve for stable work. In reality can be too cold, the heat cycle, increased .cooling medium velocity and flow method implementation to stay for long ago with refrigerant of supercooled. <br> 16, suction superheated steam compression refrigeration cycle? <br> A: breathe overheating can improve quality refrigeration capacity (invalid overheating), at Unit 2 compressed .reactive power is increased, enabling the overheating of the refrigerants (such as R12, R502, etc.) of refrigerating factor will increase, while profits without overheating of the refrigerants (such as R717, etc.) then the lower refrigeration factor. Breathe too .hot to avoid wet compressed, bomb makes compressors of exhaust temperature rise. <br> 17. What is a heat cycle? those can be used as a refrigerant heat cycle, the refrigerant at = use of a heat cycle, why? <br> .A: Stirling cycle refers to the refrigeration system with recuperators, use the outflow from the evaporator temperature refrigerant gas to cool the Plains from the condenser to cool, score the supercooled liquids of a loop. To overheating favourable R12 refrigerant (such as, R502, .etc.) Used to heat cycle can improve refrigerating factor, avoid wet compressed, exhaust temperature range is not large; and the overheating of the refrigerant with no profit (such as R717, etc.) using regenerative cycle makes refrigerating factor significantly reducing and vent .rising temperature. <br> 18, condensing temperature vapour compression refrigeration system? <br> A: when evaporation temperature does not change, the condensing temperature rise, the throttling losses increase and decrease power consumption of refrigeration rations, refrigeration condensing temperature coefficient lower; .decline, decreasing the throttling losses, cooling capacity increase, the reduction in power consumption, improve refrigerating factor. <br> 19, steam LIBR absorption chiller running if heating steam pressure too high will cause? <br> A: If the heating steam pressure .too high can cause: ① ② prone to crystallize; prone to cold for water pollution; ③ exacerbate the corrosive solution. <br> 20, psychrometric chart consists of those parameter line composition of their unit? <br> A: the psychrometric chart composed .of extremely flat-line parameters: ① enthalpy line h, KJ / kg ②, moisture content line d, g / kg of dry air ③ and dry-bulb temperature line t, o, C ④ f ⑤ relative humidity line partial pressure of water .vapor, P a Pv line ⑥ heat and moisture than line ε, KJ / kg <br> 21. Why do the summer than winter bath bathroom so the fog was so thick? <br> A: the air temperature in summer than in winter ., the higher the temperature of the high to accommodate the amount of water vapor technetium. Quantity of air temperatures low, must accommodate the amount of water vapor is less, winter temperatures approaching saturation bathroom, so easy rendering fog was so thick. <br> .22, air relative humidity and moisture content are the differences? air drying and moisture capacity size by the parameters reflect? <br> A: the relative humidity is defined as humid air in the actual content of water vapour and the same temperatures and moisture the .air can have the greatest concentration of water vapor, it reflects the humid air in nearly saturated water vapour content; moisture content is defined as in the dry air 1kg-containing humid air in the number of grams of water vapor. Visible for both definition and .purpose are not identical. The degree of air and moisture capacity size parameters to reflect the relative humidity. <br> 23, air dry-bulb temperature, wet-bulb temperature and dew point temperature: what's the difference? relationship between? <br> .A: use a thermometer to measure the air temperature is called dry-bulb temperature t. Use gauze wrapped package thermometer gauge the temperature of the air temperature is called wet-bulb temperature ts, moist air becomes saturated said dew point temperature temperature as tl, .three different definitions. The relationship between the three are: General. T>> tl ts; saturated air. T = ts = tl. .<br> 24, the day the air temperature and relative humidity to 30oC to 50%, at night the temperature drops to 20oC, condensation occurs at night? relative humidity at night? <br> A: from psychrometric chart found the day t = .30oC, F = 50% of the dew point temperature t1 = 18.8oC, night temperatures more than t1, therefore does not produce condensation phenomenon, F = 90% relative humidity. <br> 25, on the piston compressor parts classification and composition. .<br> A: the piston compressor can often divided into seven sections: ① moving parts: piston, connecting rod and crank shaft, coupling, etc; ② suction and exhaust parts, valve plates, suction and exhaust valve etc; ③ seal parts: .piston rings and seal, gasket, etc.; ④ lubrication: oil pumps, oil filter, oil pressure control valve and so on; ⑤ body parts: crankcase and cylinder head, side cover, end cap, etc.; ⑥ Security section: fake .cover and fake cover spring, safety valve, pressure controllers, etc.; ⑦ energy regulation sections: energy control valve, uninstall the piston cylinder, oil, etc. <br> 26, probation refrigerant compressor performance curve analysis of condensation temperature, evaporation temperature .change on compressor refrigeration capacity and shaft power. <br> A: the compressor performance curve visible, when the steam temperature must, along with the condensing temperature, compressor cooling capacity reduction, shaft power increases; when condensing temperature must, as the decline of .evaporating temperature, compressor cooling capacity reduction, while also reducing shaft power. <br> 27, refrigeration compressors in the refrigeration system do? <br> A: the compressor in the refrigeration system work on refrigerants, low temperature and low pressure steam compression into .a high temperature and high pressure steam, into the condenser, the condensation of refrigerant in a liquid at normal temperature and gives off heat, so that you can cycle phase refrigerant to continue to achieve the low-temperature heat to the body-temperature object transfer .and continuous for refrigeration cycle. <br> 28. What is the process of expansion of compressor? why is this process? <br> A: in the piston compressors, piston run to TDC, because there are clearance volume of makes part of the .cylinder pressure gases within the residues, piston return, this part of the high pressure gas will expand, thus forming a compressor work cycle of the expansion process. Because the top surface of the piston and the cylinder bottom plane there are clearance between the inevitable ( .clearance), so the expansion of the piston compressor is inevitable. <br> 29, screw compressor as long as those parts? <br> Answer: screw compressors is mainly composed of body, screw (yin, Yang rotor), energy regulation spool .valve, bearings, suction-side seat, exhaust-side seat, etc. <br> 30, brief screw compressors of slide valve type energy regulation mechanism works. <br> 31, evaporator and condenser in the refrigeration system functions? <br> .32, cooling fluid evaporator press for fluid manner how the pros and cons of each classification? and range of use? <br> 33, air-water heat exchanger do? its structure is that several? <br> Answer: the air-water .heat exchanger also known as recuperator, whose role is to make the cut in front of the refrigerant liquid cooling, so from evaporator to refrigerant saturation vapor overheated, it ensures the security of the compressor, and improve the system of cooling capacity. Air-water .heat exchanger structure usually shell-coil, wound pipe, tube, and other structures. <br> 34, <br> 35, <br>> 36, <br> 37, in the refrigeration system throttle-what is the function of? .what parts installed? <br> A: throttle in vapour compression refrigeration system one of the basic equipment. Throttle valve is depressed, and adjust the flow rate of refrigerant cycle, can realize automatic adjustment of cooling capacity, ensure the refrigerant from the evaporator is .overheated. Throttle valve installed in the condenser and evaporator between and close to the evaporator of refrigerant liquid pipeline. <br> 38, gas-liquid separator in the refrigeration system what features? <br> 39, oil separator in the refrigeration system role? .<br> 40, <br> 41, <br> 51, on frequency type air conditioner work original and product characteristics. <br> A: frequency type air conditioner control by frequency converter so that the compressor speed changes, thus changing the compressor .discharge capacity, meet changing refrigeration capacity or heating purposes. Frequency conversion type air conditioner with cooling speed, a small start-up current, 50 Hz or 60 Hz different electric system, cooling capacity adjustable energy-saving effect significant characteristics. <br> 52 ., <br> 53, common temperature measuring instruments are those? respective measuring range? <br> A: common temperature measuring instruments and measuring-ask range: ① expansion thermometers, mercury (or alcohol) thermometers, temperature range-30 ~-600oC .; ② pressure thermometer. Measuring range: -60 ~ 550oC; ③ thermocouple. Temperature range-20 ~ 1600 o C ④ resistance thermometers. Temperature range of-120 ~ 550oC <br> 54, <br> 56, on air conditioner electric system .for on-site inspections are the main content? <br> A: air conditioners and electrical systems on-site examination of the main elements are: <br> ① checking power circuit; ② check some compression; ③ check starter motor and a thermal .protector, measuring whether a circuit breaker; <br> ④ check temperature controller, measuring contact-off is normal; ⑤ check the fan motor ⑥ check start capacitor and running capacitor is circuit breaker or short circuit, the capacity is reduced. <br> .63, room air conditioners during use; its cooling capacity of factors are those? <br> A: the room air conditioner in the course of its cooling capacity factors are: <br> ① outdoor air temperature and humidity; ② air temperature and humidity ., the air supply and return air temperature, air humidity ratio of heat; ③ to indoor air condition and provided fresh air; ④ air conditioner temperature of evaporation and condensation temperature. <br> 68, refrigeration and air conditioning equipment management content have those? .<br> A: the refrigeration and air conditioning equipment management: <br> ①, equipment selection and equipped ②, equipment use and maintenance <br> ③, equipment of planned maintenance ④, equipment, security measures and emergency treatment <br> ⑤ ., devices, technological transformation, updates, scrap processing ⑥, equipment technical data archiving management <br> <br> 71, the normal operation of equipment for maintenance purposes in? <br> A: the equipment normal work in maintenance: <br> .①, guarantee the safe operation of equipment, extend equipment life <br> ②, play the best equipment operating results <br> ③, meet the requirements for using the departmental use <br> 76, what is the "hydraulic hammer compressor" what .harm does it? <br> A: in the refrigeration cycle process, the liquid refrigerant enters the compressor is compressed as "liquid hammer." Liquid blow against that when liquid refrigerant is compressed into the cylinder, its rapid rise in pressure moments, far .more than the normal operation of the gas pressure shocks exhaust valve slice, it is easy to break valve plate damaged compressor, the compressor to prevent liquid hammer. <br> 77, air conditioners and start running after a short downtime of those reasons? < .br> Answer: the main reason: ① ② pressure controller failure;, exhaust condenser cooling-performing; ③ refrigerant pressure high enough, the capillary plug too low inspiratory pressure; ④ system air, exhaust air pressure is too high; ⑤ temperature controllers, .temperature sensor and the evaporator surface contact malfunction; ⑥ oil pressure too low, pressure controller jumped. <br> 78, use compressed air cooled condenser device for several high discharge pressure, the main reason for that? <br> Answer: the main reason .: ① condenser long-term use, fin damage, corrosion, heat transfer area reduction; ② condenser dirt too much heat effect difference; ③ fan flip or fan speed decreased; ④ environment temperature is too high, up to 35 degrees centigrade; ⑤ heat .load is too large. <br> 79, how to handle some of the hydraulic hammer compression? <br> A: some of the hydraulic hammer compression phenomenon is due to improper adjustment. Freon system hydraulic hammer, should promptly closed suction valve, then .down expansion valve to reduce the amount of fluid for, or stands to be processed. Liquid ammonia pose a blow, should promptly shut down, close the throttle and appropriate down air admittance valve, power-on, again, slowly open the inspiratory valve, .observing inspiratory pressure and make adjustments; liquid hammer should be closed when serious high pressure valve and let the liquid in the compresses a few, in post, debug. <br> 80, air conditioner capillary or filter blockage, compressor operation appears current what changes .will occur? piston-type compressors are what the consequences? <br> A: the capillary or filter blockage, inspiratory pressure lower or even negative pressure, the compressor suction gas than volume increases, the load is reduced, so the compressor running current decline .. Due to the high suction Superheat of steam and heat reciprocating friction piston makes compressors of temperature rise, the final result in overheating protector disconnect; if overheat protector failure, may also make a few motor compression due to overheating and burning. <br> Blanks .<br> 1. impact of piston-type compressor gas coefficient λ factors (clearance volume), (suction valve gate resistance), (gas and steam cylinder wall heat), (leakage loss). <br> 2. air conditioning indicators commonly .used "2", this is the fourth degree (temperature, humidity), (cleanliness), (wind speed). <br> 3. refrigerating plant of evaporating temperature to be according to the cooling () and its () to determine. .For direct cooling freezer natural convection when the air is, compared toLibrary of temperature (), when using the air force circulation to thirty, than the average temperature of cooling liquid (). <br> <br>.