HCR OF HEAT PUMP ROOM AIR CONDITIONER IN CHINA. Beijing , China

Transcription

1 OF HEA PUMP ROOM AIR CONDIIONER IN CHINA Baolong Wang 1, Wenxing Si 1, uan Cen 1 1 Department of Building Sciencesingua University, Beijing , Cina ABSRAC Definition of eating/cooling capacity ratio () of te eat pump air conditioner as been put forard in tis study, and te relationsip beteen supply ( S ) and demand ( D ) as been illustrated. Based on te simulated ourly loads of a typical residential building in Haerbin, Beijing, Sangai and Senzen faced to different directions and it different air conditioner running scedules along it te performance of te eat pump air conditioner under varied conditions, te demand eating capacity, cooling capacity and D in different climate subareas ave been ascertained. Secondly, a simulation model as built to study te effect of different pysical parameters, include te parameters of te indoor eat excanger, door eat excanger and compressor, on of te conventional fixed speed eat pump system to researc te possibility to matc te D and in Cina. KEYWORDS Heating/cooling capacity ratio, Simulation; Heat pump, Room air conditioner, Cooling/Heating load INRODUCION Cina as a ide territory and te different places ave quite different climates, so Cina is divided into 5 different climate subareas in Cinese national standard (1993). Because of te diversity of climate, envelop of te building, te operation abits, and termal comfort of te user, te cooling and eating load of te building in different areas is obviously different. Hereby, te eat pump air conditioner selected according to te cooling capacity maybe does not satisfy te eating need of te room. Vice versa. e eating/cooling capacity ratio () conception is brougt forard under tis situation. Yu (1998) and Wang (2001) defined as te ratio of te rated eating capacity to te rated cooling capacity of a room eat pump air conditioner. ey pointed tat because te general eat pump room air conditioner is designed under its cooling orking condition, te air conditioner can satisfy te cooling demand but sometimes can t satisfy te eating demand in actual operation. e autors investigated 683 different constant speed eat pump air conditioners sold in Cinese market, and te conclusion is te of te constant speed 10 Mean= S Probability Cooling Capacity(kW) S (a) VS. Cooling Capacity (b) distribution Fig.1 of room air conditioner in Cinese market

2 eat pump air conditioners varies in a small range, from to 3 (Fig.1), and te average is ab ereby, it is necessary to researc eter te eat pump air conditioners sold in Cinese market can satisfy bot te cooling demand and eating demand of different buildings in different climate sub areas and if tere is opportunity to develop air conditioners it different to satisfy te different D of different room. DEFINIION OF SUPPLY AND DEMAND In actual, tere are to different conceptions of : te first one is te ic can be provided by te air conditioner. It is te ability of te macine and defined as supply ( S ). e second one represents te ratio of te required eating and cooling capacity of te room. It is te property of te room and defined as demand ( D ). e definitions are as folloing. (1) S (Supply Heating/Cooling capacity Ratio): te ratio of te rated eating capacity and te rated cooling capacity of te eat pump room air conditioner. S, rated c, rated = (1) Were, te rated capacity is measured under te rated conditions of te national standard (2004). It can be found tat te S is a performance parameter of te air conditioner and connected it te eat excangers, compressor and oter accessories. (2) D (Demand Heating/Cooling capacity Ratio): te S of te air conditioner ic satisfies te requirement of te eating and cooling of te specific room in a ole year. If te eat pump air conditioner as a S equaling to D of te room, it means tat te cooling capacity of te air conditioner can fitly matc te cooling need of te room and it also can fitly satisfy te eating need of te room. According to te definition, it can be seen tat te D is related it not only te load of te room but also te performance of te eat pump room air conditioner under non-rated conditions. It describes te requirement of te room. So te D can be expressed as te ratio of te demand rated eating capacity and te demand rated cooling capacity. D, c, = (2) Were,,rated,D is te demand rated eating capacity and c,rated,d is te demand rated cooling capacity. ey are te maximums of te rated eating and cooling load in a ole year., c, = max[ f ( HL, = max[ f 1 2 ( CL,,, in in in, in, )] )] (3) Were, f 1 and f 2 is te transform functions. ey can calculate and put te rated eating/cooling capacity of te air conditioner ic can eliminate te eating load HL/cooling load CL en te door temperatures are and,w (et bulb temperature) and te indoor temperature are in and in,w (et bulb temperature). For te common eat pump room air conditioner suitable for 1 climate, en te door temperature is under -7, its performance ill decrease quickly (2005). So a assumption is raised in tis researc: te eating load under -7 is met by oter eating metods and not considered by te eat pump room air conditioner. CALCULAION OF D S is a parameter based on te rated parameters of te air conditioner and can be easily obtained. Hoever, D is related it te load of te room and performance of te air conditioner, and its calculation is more complex tan S. Indeed, D can be gained according te folloing tree steps: (1) Calculate te ourly load of te room; (2) Calculate te ourly rated capacity of te air conditioner satisfying te ourly load; (3) Get te rigt maximum rated eating capacity and cooling capacity, get D. e ourly load of te room can be obtained based on te simulation toolkit DeS (2005) and te calculation of D is a piece of cake after te

3 acievement of te ourly capacity. e calculation of te rated capacity of te air conditioner based on te load under a certain environment is te most important and complex part of te calculation of te D. As e kno, for a certain eat pump room air conditioner it a rated eating capacity,rated under te rated eating condition (temperature: indoor 20 /door 7 ; influence of umidity is neglected), te eating capacity ill decrease or increase as te cange of te indoor and door temperature. ) = f ( ) (4) ( in 3, rated in So te function (4) can be rearranged as a function of to calculate te rated eating capacity of te air conditioner. ' (7,20) = f ( ) (5), rated 3 in In te same ay, te rated cooling capacity can be gotten according to an ourly cooling load of te room. ' (35,27) = f ( ) (6) c, rated 4 c in Based on tis consideration, te ourly rated cooling or eating capacity can be calculated if te non-rated performance of te air conditioner is knon. Actually, te non-rated performance of different air conditioner is quite different and ard to acquire. A simplified calculated metod in te national standard (2004) is utilized in tis paper to illuminate te principle. For cooling, te transform function can be expressed as: 1+ (27 in c (7) c = CL(, ), rated in Were, te numerator of te rigt side is te influence of te indoor temperature, ic means te c,rated increases α c en te indoor temperature decreases 1. e denominator of te rigt side is te modification of te door temperature. For eating, te transform function can be expressed as: (20 in (8), rated = HL( in ) ( 8.5) Were, te numerator of te rigt side is te influence of te indoor temperature, ic means te,rated increases α en te indoor temperature increases 1. e denominator of te rigt side is te modification of te door temperature. Wen te eating load is measured at te door temperature -8.5, te rated eating capacity sould be 6 (=1/( )) times of te eating load. Wen te air conditioner is eating during door temperature -8.5~5.5, te evaporator ill frost. A correction is done based on function (8). ( 8.5) (20 in rated = ( ) HL( 2 ( 8.5) ( 8.5) ), in (9) Using function (7)~(9), te ourly rated capacity of te air conditioner satisfying te ourly load can be calculated. Based on te simulated ourly loads of a typical residential building in Haerbin, Beijing, Sangai and Senzen faced to different directions and it different air conditioner running scedules along it te aforementioned calculation metod, te D of 480 cases are obtained. eir ranges and distributions are soed in table 1 and Fig.2. able 1 D range of buildings in four major cities of Cina Energy saving Building Common Building Haerbin Beijing Sangai Senzen 3~ ~ ~6 0~ ~ ~3.58 8~4 0~0.57 As a conclusion, it can be found: (1) te D of te energy-saving building is smaller tan te D of te common building, ic means tese energy-saving tecniques ave a more poerful influence on te eating tan on te cooling; (2) from

4 10 哈尔滨 HRB 北京 BJ 上海 SH 深圳 SZ 10 哈尔滨 HRB 北京 BJ 上海 SH 深圳 SZ 8 8 百分比 Percentage 百分比 Percentage [0,0.5) [0.5,1) [1,1.5) [1.5,2) [2,2.5) [2.5,3) [3,3.5) [3.5,4) [4,4.5) [4.5,5) [5,5.5) [0,0.5) [0.5,1) [1,1.5) [1.5,2) [2,2.5) [2.5,3) [3,3.5) [3.5,4) [4,4.5) [4.5,5) [5,5.5) [5.5,6) D D *HRB: Haerbin; BJ: Beijing; SH: Sangai; SZ: Senzen (a) Energy-saving Building (b) Common Building Fig.2 D distribution of buildings in four major cities of Cina able 2 Effects of parameters of indoor eat excanger on S Increase Ro Increase Column Increase Wind Speed Heating Capacity Increase, appreciably Increase, appreciably Increase, appreciably Cooling Capacity Increase, obviously Increase Increase COP EER Increase Increase; No effect en column increases from 2 to 3 Increase Variation ROW Column Air-Flo Range 0.95~5 ~ ~5 *ACG C : carge te air conditioner according to cooling condition *ACG : carge te air conditioner according to eating condition s Cina to nort Cina, te D increases gradually due to te increase of eating need; (3) te D of Senzen is close to 0, so a single cooling air conditioner is enoug; Haerbin sould use oter metods for eating because its D is far bigger tan te S of te common eat pump air conditioner; a common or eating-enanced eat pump room air conditioner can meet te eating and cooling need of building in Sangai and Beijing. e researc to enance te eating capacity of room air conditioner is significant for tese areas. FACOR ANALYSIS ON S e ays to cange te eating or cooling capacity include te inverter compressor, multi stage system, refrigerant injection, and so on. Here, e just talk ab te possibility of adjusting te self parameters of te air conditioner to cange te S. If it is possible, te eat pump air conditioner oriented to different areas can be easily designed to satisfy different needs of different places. e variable parameters in te common constant speed eat pump air conditioner include te parameters of te evaporator, condenser, and compressor. e effects of tese factors on te performance of te air conditioner are listed in able 2, 3, and Fig.3.

5 able 3 Effects of parameters of door eat excanger on S Increase Ro Increase Column Increase Wind Speed Heating Capacity Increase, obviously Increase Increase Cooling Capacity Increase, appreciably Increase, appreciably Increase, appreciably COP EER Increase, appreciably Increase, appreciably No cange Increase, logaritmically Variation ROW Column Air-Flo Fig.3 Effect of te compressor capacity on te S Generally speaking, te variation of te parameters of te air conditioner as limited effect on te supply (around 1.1, from 0.95 to 1.15). Some oter tecnologies, suc as gas refrigerant injection, must be used to make a eat pump room air conditioner it a variable S. CONCLUSION Range 5~1.15 ~1.15 7~1.12 *ACG C : carge te air conditioner according to cooling condition *ACG : carge te air conditioner according to eating condition S ARI rated cooling capacity ARI 额定制冷量 (kw) e definition of supply and demand eating/cooling capacity ratio ( S and D ) of te eat pump air conditioner as been put forard in tis study, and teir calculation metods are illustrated. Based on te simulated ourly loads of a typical residential building in Haerbin, Beijing, Sangai and Senzen faced to different directions and it different air conditioner running scedules, te demand eating capacity, cooling capacity and D in different climate subareas ave been ascertained. As a result, it is found tat: te D of Senzen is close to 0 and a single cooling air-conditioner is enoug; Haerbin sould use oter metods for eating because its D is far bigger tan te S of te common eat pump air conditioner; a common or eating-enanced eat pump room air conditioner can meet te eating and cooling need of building in Sangai and Beijing. e researc to enance te eating capacity of room air conditioner is significant for tese areas. ereby, a simulation model as built to study te possibility of adjusting te self parameters of te air conditioner to cange te S. Hoever, te factor analysis sos: te variation of te parameters of te air conditioner as limited effect on te supply. Some oter tecnologies must be used to make a eat pump room air conditioner it a variable S. REFERENCE Cinese National Standard GB Design Criterion for Civil Building. Jianling YU, Mingxin FU, i Cao et al Analysis on te of te eat pump room air conditioner. Fluid Mecanism, 28(8): aiyu Wang, Guangqing Wang Comments on te standard of inverter air conditioner. Houseold Appliance ecnology, 8: Cinese National Standard GB/ Room Air Conditioner. DeS HVAC simulation oolkit Department of Building Sciencesingua University.