Experimental Assessment on Performance of a Heat Pump Cycle Using R32/R1234yf and R744/ R32/R1234yf

Transcription

1 Purdue Univerity Purdue e-pub International Refrigeration and Air Conditioning Conference School of Mechanical Engineering 2016 Experimental Aement on Performance of a Heat Pump Cycle Uing R32/R1234yf and R744/ R32/R1234yf Sho Fukuda Kyuhu Univ., Japan, fukuda@phae.cm.kyuhu-u.ac.jp Hedeki Kojima Kyuhu Univ., Japan, kojima@phae.cm.kyuhu-u.ac.jp Chieko Kondou Nagaaki Univ., Japan, ckondou@nagaaki-u.ac.jp Nobuo Takata Kyuhu Univ., Japan, takata@cm.kyuhu-u.ac.jp Shigeru Koyama Kyuhu Univ., Japan, koyama@cm.kyuhu-u.ac.jp Follow thi and additional work at: Fukuda, Sho; Kojima, Hedeki; Kondou, Chieko; Takata, Nobuo; and Koyama, Shigeru, "Experimental Aement on Performance of a Heat Pump Cycle Uing R32/R1234yf and R744/R32/R1234yf" (2016). International Refrigeration and Air Conditioning Conference. Paper Thi document ha been made available through Purdue e-pub, a ervice of the Purdue Univerity Librarie. Pleae contact epub@purdue.edu for additional information. Complete proceeding may be acquired in print and on CD-ROM directly from the Ray W. Herrick Laboratorie at Herrick/Event/orderlit.html

2 2205, Page 1 Experimental Aement on Performance of a Heat Pump Cycle Uing R32/R1234yf and R744/R32/R1234yf Sho FUKUDA 1 *, Hideki KOJIMA 2, Chieko KONDOU 3, Nobuo TAKATA 2, and Shigeru KOYAMA 1,4 1 Faculty of Engineering Science, Kyuhu Univerity Kauga, Fukuoka, , Japan Phone: , Fax: , fukuda@phae.cm.kyuhu-u.ac.jp 2 Interdiciplinary Graduate School of Engineering Science, Kyuhu Univerity Kauga, Fukuoka, , Japan 3 Graduate School of Engineering, Nagaaki Univerity Bunkyo-machi, Nagaaki, , Japan 4 International Intitute for Carbon-Neutral Energy Reearch, Kyuhu Univerity Motooka, Nihi-ku, Fukuoka , Japan ABSTRACT Thi tudy meaure the COP of R744/R32/R1234yf and R32/R1234yf with GWP of approximately 300 and 200 under two heating mode in experimentally and analytically, where the heat ink water change temperature 10 K and 25 K. In experiment, COP of Ternary 300 and Binary 300 are comparable to that of. In analyi, COP of Ternary 300, Binary 300 and Binary 200 are higher than that of. Even if temperature glide of zeotropic mixture equal to water temperature change in the heat exchanger, irreverible lo in heat exchanger increae becaue of lower heat tranfer performance of heat exchanger. COP of Ternary 300, Binary 300 and Binary 200 are higher than that of in experiment if compreor i improved and the diameter of connecting pipe and heat exchanger i increaed. 1. INTRODUCTION Hydro-fluorocarbon (HFC) are widely ued a refrigerant in air-conditioning and refrigeration ytem. At the 1997 Kyoto Conference (COP3), it wa determined that the product and ue of HFC hould be regulated due to their high global warming potential (GWP). Therefore, everal tudie related to Hydro-fluoro-olefin (HFO) have been reported in the pat decade. In the above mentioned ituation for the air-conditioning and refrigeration ytem, recently, R1234yf i nominated a one of the alternate of HFC, due to it extremely low GWP. The heating capacity of heat pump cycle uing R1234yf i, however, expected to be lower than that of currently mot ued, becaue of it lower vapor denity and latent heat. To achieve performance equal to, much larger unit i required. In the previou tudie (Kojima et al., 2015), drop-in experiment on heat pump cycle uing mixture of R1234yf/R32 wa carried out; R32 wa elected a the econd component to increae vapor denity and latent heat. It wa found that mixture of R1234yf/R32 were trong candidate for replacing. In thi tudy, adding, to reduce GWP furthermore a maintaining the volumetric capacity, adding R744 to R-32/1234ze(E) wa therefore attempted. On other hand, the mixture of R744/R32/R1234yf and R32/R1234yf are zeotropic and have a temperature change during the phae-change, typically called temperature glide. When the temperature glide i utilized effectively, the irreverible lo or exergy lo in heat exchanger i reduced and the cycle performance i improved (e.g., Jakob and Krue, 1978, Krue, 1981, McLinden and Radermacher, 1987, Swinney et al., 1998). The temperature glide i determined by the compoition and preure of refrigerant mixture.

3 2205, Page 2 In thi tudy, the cycle performance of the binary mixture R32/R1234yf and the ternary mixture R744/R32/R1234yf are experimentally compared for their compoition correponding to GWP of 200 and 300. Additionally, to undertand the feaibility of zeotropic refrigerant, irreverible loe in each element are dicued on the experimental data that changing heat ink water temperature of condenation inlet and outlet 2. EXPERIMENTAL SETUP AND METHOD 2.1 Experimental Setup Figure 1 how an experimental apparatu, which i a water heat ource vapor compreion cycle. The experimental apparatu conit of three loop of refrigerant, and cooling and heating water. The refrigerant loop i compoed of a manually controlled hermetic type rotary compreor, an oil eparator, a condener, a liquid receiver, a olenoid expanion valve and an evaporator. Uing contant-temperature bathe, certain temperature cooling and heating water are upplied to the condener and the evaporator. Four mixing chamber are intalled between each component in the refrigerant loop for meauring the preure and the bulk mean temperature of refrigerant. The other four mixing chamber are intalled in water loop for meauring bulk mean temperature of water. The dimenion of the condener and the evaporator are pecified in Table 1. Thoe heat exchanger are both 7200 mm long counter flow double-tube type coil. The refrigerant flow in the inner micro-fin tube, while the water imulating cooling or heating load flow the annulu. Circulating ubcooled liquid i ampled at the inlet of expanion valve and the ma fraction of each component are meaured by the ga chromatography. 2.2 Experimental Method Tet condition: Table 2 lit the experimental condition at heating mode 1 and heating mode 2. The degree of uperheat at evaporator outlet i fixed at 3 K for entire experimental condition. For heating mode 1, water temperature are fixed a follow. At condener inlet and outlet, they are kept at K and K, repectively. At evaporator inlet and outlet, they are kept at K and K, repectively. Similarly, for heating mode 2, water temperature at condener inlet and outlet are kept at K to K, repectively, and water temperature at evaporator inlet and outlet are kept at K and K, repectively. In two heating mode, the heating load i 2.2 kw Tet refrigerant: Table 3 lit the tet refrigerant and their propertie: GWP of a 100 year time horizon, normal boiling point, temperature glide at average temperature of K, and volumetric capacity defined a the product of latent heat and aturated vapor denity. The compoition of the ternary mixture R744/R32/R1234yf Figure 1: Schematic view of experimental apparatu Table 1: Specification of the heat exchanger Outide diameter [mm] Inide diameter [mm] Length [mm] Type of tube Condener Outer tube Smooth tube Inner tube Micro-fin tube Evaporator Outer tube Smooth tube Inner tube Micro-fin tube

4 Table 2: Experimental condition Heating mode 1 Heating mode 2 Heat ource temperature [K] (ΔT = 6 K) Heat ink temperature [K] (ΔT = 10 K) (ΔT = 25 K) Degree of uperheat [K] 3 Heat tranfer rate [kw] (Heating/cooling heat load) 2.2 Table 3: Comparion of propertie between tet refrigerant deignation compoition (ma%) GWP 100 NBP Temp. glide * vol. capacity * 2205, Page 3 [K] [K] [MJ m -3 ] (Ternary300) R744/R32/ 4/44/ (Ternary200) R1234yf 5/28/ (Binary300) R32/ 43/ (Binary200) R1234yf 28/ *Bulk temperature K and binary mixture R32/R1234yf are determined from the criteria at GWP 100 of 200 and Data reduction The heating load, namely, the heat tranfer rate in the condener i calculated from the refrigerant-ide heat balance, a follow: Q m h h (1) COND ref COND,in COND,out The heat tranfer rate Q COND correpond to the capacitie or the heat load of the heating mode operation. The deviation of thoe heat load wa confirmed to be within 5 %. COP of heating mode, COP h i obtained from the above heat load and the compreion work, W COMPR, which i found from the pecific enthalpy difference between the compreor uction and dicharge. Q h COND COND,in hcond,out COPh (2) W h h COMPR COMPR,out COMPR,in The COP h take into account the compreor ientropic efficiency, but not the mechanical, volumetric, and inverter efficiencie. The propagated meaurement uncertainty in the COP h wa within 5%. For the performance aement of heat pump cycle, the irreverible lo (de Roi et al., 1991) i calculated a follow. The total irreverible lo during cycling, L total, can be divided into the following irreverible loe of the main element (e.g., compreor and evaporator) and alo the heat lo and preure drop, a follow: Ltotal LCOND LEVA LEXP LCOMPR LH LP (3) Figure 2 illutrate irreverible loe generated in condener, evaporator, expanion valve, compreor (departure from the ientropic compreion), and connecting pipe in a T- diagram. In the figure, water temperature and refrigerant temperature are plotted againt the entropy generation rate. The irreverible loe per refrigerant ma in each component are calculated a follow, COND, out LCOND T R TW d (4) COND, in LEVA TW TR d (5) EVA, out EVA, in EXP,out LEXP TR d (6) EXP,in

5 2205, Page 4 Figure 2: Irreverible lo in each element Figure 3: Irreverible lo by preure drop L COMPR, out COMPR TR d (7) COMPR,in Figure 3 illutrate the irreverible lo caued by preure drop in a T- diagram. The olid line denote an actual cycle and the dahed line denote an ideal cycle without preure drop. The irreverible loe caued by preure drop are expreed a hatched area edged by the olid and dahed line. 3. THERMODAINAMIC ANALYSIS METHOD 3.1 Calculation condition of thermodynamic analyi Table 4 lit the analyi condition at heating mode 1 and heating mode 2 that i the ame a experimental condition. Efficiency of compreor i 1.0 to calculate ideal cycle. Calculated refrigerant are the ame a experimental tet refrigerant in table Calculation method of thermodynamic analyi The calculation of type A and Type B are carried out. A hown in Figure 4(a), the calculation of type A i that Table 4: Analyi condition Heating mode 1 Heating mode 2 Heat ource temperature [K] (ΔT = 9 K) Heat ink temperature [K] (ΔT = 10 K) (ΔT = 25 K) Degree of uperheat [K] 3 Heat tranfer rate [kw] (Heating/cooling heat load) 2.2 Efficiency of Compreor [-] 1.0 (a) type A (temp. glide i maller) (b) type B (temp. glide i larger) Figure 4: Calculation method of thermodynamic analyi

6 2205, Page 5 temperature glide of refrigerant i maller than water temperature difference in the heat exchanger inlet and outlet. On the other hand, the calculation of type B i that temperature glide of refrigerant i larger a hown in Figure 4(b). The condenation and evaporation preure i decided o that pinch point (temperature difference between refrigerant and water) become 0 K. 4. EXPERIMENTAL AND ANALYSIS RESULTS 4.1 Coefficient of performance (COP) Figure 5 how coefficient of performance for heating mode 1 and heating mode 2 in the experiment, where blue, red, green, purple and orange repreent the reult obtained for ternary 300, ternary 200, binary 300, binary 200 and, repectively. The refrigerant charge i varied to find the maximum COP during the experiment. The optimized charge i determined a the refrigerant amount exhibit the highet COP at the mot of condition for each tet refrigerant. The erie of experimental data are obtained at that optimized refrigerant charge. For the heating mode 1, the COP of ternary300 and binery300 are comparable to that of. The COP of ternary 200 and binary 200 are lower than that of. For the heating mode 2, the COP trend due to difference in refrigerant i the ame a that of heating mode 1. The difference in COP due to difference in refrigerant of heating mode 2 i, Figure 5: COP in the experiment Figure 6: COP in the analyi T [K] (a) Experimental reult (b) Analyi reult Figure 7: Irreverible lo in condener Ternary300 Ternary200 Binary300 Binary200 Water Heating mode1 T [K] Ternary300 Ternary200 Binary300 Binary200 Water Heating mode Q COND [kw] Q COND [kw] (a) heating mode 1 (b) heating mode 2 Figure 8: Temperature ditribution in condener in experiment

7 2205, Page 6 however, maller than that of heating mode 1. Figure 6 how COP for heating mode 1 and heating mode 2 in the analyi. For heating mode 1, the COP of ternary 300, binary 300 and binary 200 are higher than that of. For heating mode 2, the COP trend due to difference in refrigerant i the ame a that of heating mode 1. The difference in COP due to difference in refrigerant of heating mode 2 i, however, maller than that of heating mode 1. Compared with reult in experiment and reult in analyi, the COP trend due to difference in refrigerant in experiment differ from that in analyi. 4.2 Irreverible Lo of Condener, Evaporator and Expanion Valve Figure 7 (a) and (b) how irreverible lo in condener in experiment and analyi for heating mode 1 and heating mode 2. Symbol indicate the refrigerant in the ame rule a in Figure 5. For heating mode 1, the irreverible lo in condener of Ternary 200 i the larget among tet refrigerant in experiment (Figure 7 (a)); the irreverible lo in condener of i, however, the larget among tet refrigerant in analyi (Figure 7 (b). For heating mode 2, the trend of irreverible lo in condener due to difference in refrigerant in experiment i the ame a that in analyi. The irreverible loe generated in condener are determined by the mean temperature difference between refrigerant and heat ink water. Figure 8 (a) and (b) explain the temperature ditribution in condener for heating mode 1 and heating mode 2 in experiment. For heating mode 1, mean temperature difference between and heat ink water i the mallet and mean temperature difference between Ternary 200 and heat ink water i the larget depite the temperature glide of Ternary 200 equal to water temperature change in the condener. Thee caue are lower heat tranfer coefficient of zeotropic mixture and lower heat tranfer performance of heat exchanger. For heating mode 2, in all refrigerant, the temperature difference between refrigerant and heat ink water in condening tart point are much the ame. Thu the trend of irreverible lo in condener due to difference in refrigerant in experiment i the ame a that in analyi. Figure 9 (a) and (b) how irreverible lo in evaporator in experiment and analyi for heating mode 1 and heating mode 2. Symbol indicate the refrigerant in the ame rule a in Figure 5. Both in experiment reult and analyi reult, in all tet refrigerant, the irreverible loe in evaporator for heating mode 1 are the ame a that for heating mode 2. For heating mode 1 and heating mode 2, the trend of irreverible lo in condener due to T [K] (a) Experimental reult (b) Analyi reult Figure 9: Irreverible lo in evaporator Ternary300 Ternary200 Binary300 Binary200 Water Heating mode1 T [K] Ternary300 Ternary200 Binary300 Binary200 Water Heating mode Q EVA [kw] Q EVA [kw] (a) heating mode 1 (b) heating mode 2 Figure 10: Temperature ditribution in evaporator in experiment

8 2205, Page 7 difference in refrigerant in experiment i the ame a that in analyi except irreverible lo in evaporator of Binary 300 in experiment i higher than another refrigerant. The irreverible loe generated in evaporator are determined by the mean temperature difference between refrigerant and heat ource water. Figure 10 (a) and (b) explain the temperature ditribution in evaporator for heating mode 1 and heating mode 2 in experiment. The temperature ditribution in evaporator for heating mode 1 are the ame a that for heating mode 2 in all tet refrigerant. For heating mode 1 and heating mode 2, temperature difference between Binary 300 and heat ink water i the larget among tet refrigerant in evaporating end point depite the temperature glide of Binary 300 equal to water temperature change in the evaporator. Therefore, a reult of irreverible lo in condener and evaporator, even if temperature glide of zeotropic mixture equal to water temperature change in the heat exchanger, irreverible lo in heat exchanger increae becaue of lower heat tranfer performance of heat exchanger. Figure 11 (a) and (b) how irreverible lo through expanion value in experiment and analyi for heating mode 1 and heating mode 2. Symbol indicate the refrigerant in the ame rule a in Figure 5. For heating mode 1 and heating mode 2, the trend of irreverible lo through expanion valve due to difference in refrigerant in experiment i the ame a that in analyi 4.3 Irreverible Lo of Compreor and Preure Drop Figure 12 how irreverible lo in compreor in experiment for heating mode 1 and 2. On other hand, irreverible lo in compreor in analyi i not exit becaue efficiency of compreor i 1.0 in thi analyi. For heating mode 1 and 2, the irreverible lo in compreor of R410 i the mallet among tet refrigerant. At zeotropic mixture, the more the temperature glide i large, the more the irreverible lo in compreor i large. In other word, the more the thermophyical property of zeotropic mixture i different from that of, the more the irreverible lo in compreor i large. Thi caue i that compreor and compreor oil in thi tudy are compreor and compreor oil for. Therefore, the irreverible lo in compreor of zeotropic mixture decreae if compreor i improved. (a) Experimental reult (b) Analyi reult Figure 11: Irreverible lo through expanion valve Figure 12: Irreverible lo in compreor Figure 13: Irreverible lo caued by preure drop

9 2205, Page 8 Figure 13 how irreverible lo caued by preure drop for heating mode 1 and 2. On other hand, irreverible lo caued by preure drop in analyi i not exit becaue preure drop i ignored in thi analyi. For heating mode 1 and 2, the more the volumetric capacity i mall, the more the irreverible lo caued by i large. Therefore, the irreverible lo caued by preure drop decreae if the diameter of connecting pipe and heat exchanger i increaed. 4. CONCLUSIONS The COP of four tet refrigerant,, R32, R1234ze(E)/R32(20/80 ma%), and R1234ze(E)/R32 (50/50 ma%) ha been experimentally and analytically evaluated with a heat pump cycle. The concluding remark are a follow: (1) For heating mode 1 and 2, in experiment, COP of Ternary 300 and Binary 300 are comparable to that of. In analyi, COP of Ternary 300, Binary 300 and Binary 200 are higher than that of (2) Even if temperature glide of zeotropic mixture equal to water temperature change in the heat exchanger, irreverible lo in heat exchanger increae becaue of lower heat tranfer performance of heat exchanger. (3) COP of Ternary 300, Binary 300 and Binary 200 are higher than that of in experiment if compreor i improved and the diameter of connecting pipe and heat exchanger i increaed. NOMENCLATURE COP coefficient of performance ( - ) Subcript h enthalpy (kj kg -1 ) COND condener L irreverible lo (kj kg -1 ) COMPR compreor m ma flow rate (kg -1 ) EVA evaporator Q heat tranfer rate (kw) EXP expanion valve T temperature (K) H heat lo entropy (kj kg -1 K -1 ) h heating mode W compreion work (kw) in inlet R refrigerant out outlet P preer drop REFERENCES de Roi, F., Matrullo, R., Mazzei, P., (1991). Working fluid thermodynamic behavior for vapor compreion cycle. Appl. Energy, 38, Jakob, R., Krue, H., (1978), The ue of non-azeotropic refrigerant mixture in heat pump for energy aving, Proceeding of IIR Commiion B2, Delft( ), Netherland: IIR Kojima, H., Fukuda, S., Kondou C., Takata, N., Koyama, S., (2015), Comparative aement of heat pump cycle operated with R32/R1234ze(E) and R32/R1234yf mixture, Proceeding of The 24 th IIR International Congre of Refrigeration, Yokohama (1-8). Kanagawa, Japan: IIR Krue, H, (1981), The advantage of non-azeotropic refrigerant mixture for heat pump application, Proceeding of IIR Commiion D1, D2, E1, and E2, ( ): IIR McLinden, M.O., Radermacher, R., (1987), Method of comparing the performance of pure and mixed refrigerant in the vapour compreion cycle, Int. J. Refrig., 10, Swinney, J., Jone, W.E., Wilon, J.A., (1998), The impact of mixed non-azeotropic working fluid on refrigeration ytem performance, Int. J. Refrig., 21(8),