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1、外文翻译(英文原文)ABSTRACTThe working principles and the basic features of air conditioning water heater (ACWH) system are introduced in this paper. The air conditioning water heater system can operate in five modes: water-heating only, space-cooling and water-heating, space-heating and water-heating, space
2、-cooling, space-heating. Comparatively, the system can provide much better energy performance and higher equipment utilization throughout a year, and cause less thermal pollution than heat pump water heater and common air conditioner. A prototype with five modes was assembled and tested at the ambie
3、nt temperature from -7 to 43, especiallywhen frosting. When it works in the water-heating mode, it can supply 55 hot water within two minutes, and thecondensing pressure is just same with common air conditioner. When some modes switch, the temperature of theoutlet hot water is constant. Theoretical
4、analysis and experimental study were done to the ACWH in this thesis:1. The prototype was tested in the air-conditioner laboratory of GREE. The testing data indicate that the prototypeaccords well with the national standards of air conditioner and heat pump water heater.2. Based on the experimental
5、results, analysis was done on the ACWH in main operating modes and some importantconclusions were given，The results indicate that the new system can save energy through multi-duties, and it can work stably in five workmodes with high efficiency. Compared with other models, the new system also includ
6、es air-conditioning unit andwater heater unit, but with fewer components and higher reliability. Based on common air conditioner, this systemcan offer a practicable solution coupling air conditioner and water heater. It must be changing the markets of bothair conditioner and water heater. 1. INTRODU
7、CTIONThe heat pump water heater (HPWH) has been used since 1950s, mainly for household applications. It absorbs heatenergy from the ambient air to acquire hot water. In the last 20 years, the study intends to design heat pump waterheater with high reliability and practicability, and many manufacture
8、rs turn to offer this production based onenvironmental protection and energy saving. In South Africa, HPWH has penetrated 16 percent of the market sharefor commercial water heaters.Because of the highly primary cost, it is difficult to become the alternative to the common water heater. However, ifwe
9、 can offer an air conditioner coupled with HPWH system, which can act as air conditioner and water heater withthe main components such as heat exchangers, compressor, four-way valve, and capillary tube, the primary cost willbe reduced and it can realize multifunction easily. In summer, with the reco
10、very of the waste heat of condensation, itcan offer “free” hot water, and also can improve the coefficient of performance (COP) of the air conditioner. Whenair conditioner is not required in spring and autumn, it can operate in HPWH mode. As the enhancement of the yearroundutilization, it can be mor
11、e efficient and is expected to become a strategy solving the air conditioning and hotwater applications. Here we demonstrate an air conditioning water heater (ACWH) system, and the performanceanalysis is described in this article.1. THE PRINCIPLE OF ACWHThe schematic diagram of air conditioning wate
12、r heater system is shown in Figure 1. The system can offer thefollowing five operating modes. Mode 1 is only for heating water; mode 2 can act as space-cooling and waterheating;mode 3 can realize both space-heating and water-heating; the other two modes are the same with thecommon air-conditioning c
13、ircles. The switching among all these modes is by means of on-off controls of thesolenoid valves and four-way valve. Each mode will be demonstrated as follows.1.1 Water Heating Mode2.1 Water Heating ModeThe system can operate in two heating modes. The one is direct heating water; the other is heatin
14、g water with waterrecycle in the adiabatic water tank. The controller can adjust the operating mode according to the water level sensorsin the tank. A water valve is placed at the hot water outlet which can be adjusted to control the water flow and keepthe condensing pressure constant. When the tap
15、water goes into the water-refrigerant heat exchanger (WRHE), itwill be heated to 50-55 directly within two minutes. If needed, the outlet water temperature can be set byadjusting the water valve.As shown in Figure 1, when the power is on, the compressor sucks low-pressure refrigerant gas and then di
16、schargeshigh-pressure gas into water-refrigerant heat exchanger (WRHE), where refrigerant is condensed and water is heateddirectly. After heat exchanges, the liquid refrigerant flows across four-way valve, then it is throttled to lowtemperatureand low-pressure liquid and gas by an electronic expansi
17、on valve. Refrigerant flows into outdoor aircooledcondenser where it is evaporated and becomes low-pressure gas. When the low-pressure gas returns to thecompressor, the circle begins again. In this mode, valve 1 is closed and valve 2 is open. When heating water, theoutdoor air-cooled unit acts as ev
18、aporator, and the indoor fan doesnt run. The COPw is presented as a function ofpower Qw and the electric power W as shown in Equation (1).COPw=Qw / W=MCT (1)Where M is the mass flow of water; C is the specific heat of water;T is the water temperature difference betweenoutlet and inlet of the water-r
19、efrigerant heat exchanger (WRHE).1.2 Space-cooling and Water-heating (SCWH) ModeIn summer, with the recovery of condensing heat, the indoor air is cooled down at the same time. Compared withwater-heating mode, the high-temperature refrigerant is also condensed in the WRHE directly, and then goesthro
20、ugh the air-cooled condenser to be super-cooled where the outdoor fan doesnt run. It is throttled by capillary 1to low-temperature liquid and gas, and the indoor air exchanges heat with returned refrigerant. In this mode, valve 1is open and valve 2 is closed. This mode can act as space cooling and w
21、ater heating at the same time. However, it isnot necessary to recover the entire condensing heat which can be released in the air-cooled condenser. The totalcapacity is the sum of cooling capacity Qc and heating capacity Qw, and then total COPcw can be shown as theEquation (2).COPcw=(QcQw)/W (2)2.3
22、Space-heating and Water-heating ModeRefrigerant flows across WRHE, evaporator, capillary 2, capillary1, and air-cooled condenser in turn. Space-heatingand Water-heating can realize in theory. This mode sometimes may not meet customers expectations, so that it mustoperate combined with the water-heat
23、ing mode and spacing-heating mode. If needed, an electric heater is available2.4 Space-cooling Mode and Space-heating ModeIn these two modes, refrigerant doesnt flow across WRHE or the water pump and inlet valve are closed, and thecondensing heat is completely released by the outdoor or indoor heat
24、exchanger. In fact, it is the same with a normalair conditioner, and is not described any more as above. In summer, space-cooling mode can be replaced by theSCWH mode, which can use the water-cooled and air-cooled heat exchangers at the same time. The performance ofthe system will be improved signif
25、icantly with the enhancement of heat transfer.3. EXPERIMENTSExperimental research was performed at an air-enthalpy test laboratory which can also supply water with requiredtemperature and mass flow. The laboratory includes outdoor chamber, indoor chamber and control room. It consistsof insulated wal
26、ls, air-handling equipments, temperature and humidity collection system, air volume testingequipment, electric control system and computer handling unit. The cooling and heating capacity can be tested byair-enthalpy test. Air handling equipments are provided in both test chambers to control the dry
27、bulb and wet bulbtemperatures, as well as humidity. The indoor unit of air conditioning was placed in one chamber; the outdoor unitand adiabatic storage tank were placed in another chamber. T-type thermocouples were placed at each temperaturetest point and pressures were tested by the pressure senso
28、rs. All the testing data can be collected and displayed bythe computer handling system.3.1 Prototype DesignThe prototype includes outdoor unit, indoor unit, and an adiabatic storage tank. Based on a common air conditioner,the system adds a water-refrigerant heater exchanger, a storage tank, several
29、solenoid valves, and water pump. The storage tank is an insulated cylinder and water capacity is about 800L. The prototype was designed based on theschematic diagram shown in Figure3.2 Experimental Test ConditionsIn mode 1, the ambient temperature was from -7 to 43, and the inflow water temperature
30、was from 9 to 30.The outlet water temperature was set to 55 by adjusting the water valve. The other four modes operated only inthe nominal test conditions according to the national standards of air conditioner and heat pump water heater. Theexperimental test conditions are shown in Table4. RESULTSTh
31、is study emphasizes on the direct heating water. Mode 1 was tested in temperature conditions, while mode 2 justoperated in the standard testing condition shown in table 1. The prototype is different from a common heat pumpwater heater, which can offer hot water within 2 minutes by means of heattrans
32、fer of large temperature difference.The experimental results were discussed combined with the first two modes as follows.4.1 Hot Water OutputThe curves of hot water output are shown in Figure 2 at different inflow water and ambient temperatures. As shownin Figure 2, the hot water output tends to ris
33、e more rapidly at higher ambient temperature or inflow watertemperature. It can offer about 400L hot water each hour when the inflow water temperature is 15 and ambienttemperature is 20. From this figure, we can know that the hot water output is relative to the parameters of theinflow water and ambi
34、ent air. When the ambient temperature is 30 and the inflow water temperature is 40, thehot water output is about 800L, while it decreases sharply to 120L at -7 ambient temperature and 5 inflowwater temperate. The mass flow is also various in different conditions, so that the hot water output changes
35、accordingly. Therefore, we should choose the equipment according to the largest hot water consumption in coldweather.4.2 Variation of System ParametersExperimental results at variable inflow water and ambient temperatures are shown in Figure 3-6. As shown in Figure3, the increase of inflow water tem
36、perature causes that the heating power increases a little, and the heating capacitydecreases about 100200W, so the COPw decreases. Compared with Figure 3, Figure 4 shows that as the ambienttemperature rises, the heating capacity increases significantly, but the power consumption does not increase gr
37、eatly.Therefore, the COPw increasesFigure 5 shows that as inflow water temperature rises, the outlet water temperature, the discharge temperature andoutlet refrigerant temperature of WRHE do not increase significantly, and the inlet refrigerant temperature keepsconstant at first and then decreases o
38、bviously. As seen in Figure 6, because the outlet water temperature is constant, the condensing pressure is almost stable at about 2.1 MPa, while the evaporating pressure increases with the rise ofambient temperatureIn mode 2, when the indoor air temperature is cooled down, and the condensing temper
39、ature is constant, thecompression ratio will increase gradually even to be overloaded, especially in cold weather. For the sake of stabilityand safety, it is necessary to restrict the compression ratio. When the room temperature meets the limited value, thesystem will switch to water-heating mode, a
40、nd the evaporator turns to outdoor air-cooled heat exchanger, so that thecompression ratio can be controlled during the operation period in water-heating mode. Generally, when pipetemperature is below -2 in the indoor unit, the freezing protection will be effective, and the indoor fan doesnt runany
41、more. Then the compression ratio decreases, and the evaporating pressure rises obviously. In cold weather, thecompression ratio in mode 1 also increases gradually because of frosting, so it is important to defrost in time, whichmakes the discharging temperature and evaporating pressure under control
42、4.3 Heating Water of Large Temperature DifferenceIn Figure 7, the results of measured temperatures in the characteristic process points are presented. During operationof the system, the inlet refrigerant temperature (Tr, i) was 76C, and the condensing temperature (Tk) was about 53C.The outlet Refrig
43、erant temperature of WRHE (Tr, o) was kept constant to 42 C. The degree of super-cooled was noless than 10 C. When inflow water temperature (Tw, i) is 15C, the outlet water temperature (Tw, o) can reach 55C.By means of heat transfer of largetemperature difference, sensible heating effect is remarkab
44、le. As the flowdecreases, it is easy to realize high outlet water temperature even above the condensing temperature. For the HPWHadopting recycle heating water mode, as the inflow water temperature increases gradually, the COPw and heatingcapacity decrease sharply, and the system will be easy to be
45、overloaded. However, for this direct water-heatingmode, maximum discharging pressure is just about 2.1MPa, which is well within the safe compressor operatingrange.4.4 Coefficient of PerformanceFigure 8 shows that the COPw of water-heating mode is from 1.8 to 5.5 at different ambient temperatures. As
46、 theambient temperature rises, the COPw also increases. When the ambient temperature is -7, the water heating COPwis about 1.8. In mode 2, total COPcw is the sum of COPw and COPc. The heating and cooling capacities are 29743Wand 12198W, respectively, and the total COPcw of this system is about 6.8.
47、The COPw of heating water is above 4.0,and the COPc reaches 2.8, which is expected to be higher when the outlet hot water temperature is lower than 55.When the indoor air temperature drops, the total COPcw also decreases. Then it turns to the water-heating mode, andthe overcharged refrigerant will b
48、e removed to operate at optimal heating water cycle. On the other hand, when thewater in the tank meets the limited water level, the outdoor fan runs and the condensing heat is dispersed by the aircooledheat exchanger. All these indicate that the air conditioning water heater system can operate with
49、 highefficiency and save energy even at low ambient temperature.5. CONCLUSIONSAccording to the experimental results, the air conditioning water heater system can operate in five modes, and it canreplace air conditioner and water heater. In HPWH mode, cold water can be heated to 55 directly which is wellwithin the safe operating range. Compared with the traditional air conditioner and water heater, the prototype can