The effect of the circuit number on the indoor coil in a split-type air-source heat pump is investigated numerically by EVAP-COND 2.0 version simulation package of American NIST. The indoor coil serves as an evaporator in a cooling cycle and as a condenser in a heating cycle. The simulation demonstrates that the air-and-refrigerant temperature difference increases with the circuit number
but the overall heat transfer coefficient drops. The evaporator capacity rises firstly
and then drops with the circuit number and achieves the maximum in the optimum circuit number. The minimum evaporator capacity gets less than the maximum by 23.2%. The air-and-refrigerant temperature difference and the overall heat transfer coefficient become the dominant factor governing the evaporator capacity
respectively behind and beyond the optimum circuit number. The condenser capacity always decreases with the circuit number and the overall heat transfer coefficient acts as the dominant factor. The minimum condenser capacity is less than the maximum by 40.5%. These results demonstrate that the indoor coil in a heat pump is endowed with an optimal circuit number to heighten the efficiencies and capacity in heating and cooling cycles simultaneously.
关键词
Keywords
references
Domanski P A, Yashar D, Kim M S. Performance of a finned-tube evaporator optimized for different refrigerants and its effect on system efficiency[J]. International Journal of Refrigeration, 2005, 28(6): 820-827.
Liang S Y, Wong T N, Nathan G K. Numerical and experimental studies of refrigerant circuitry of evaporator coils [J]. International Journal of Refrigeration, 2001, 24(8): 823-833.
Liang S Y, Wong T N, Nathan G K. Study on refrigerant circuitry of condenser coils with exergy destruction analysis [J]. Applied Thermal Engineering, 2000, 20(6): 559-577.
Liu M S, Leu J S. Influence of circuitry arrangement on the pressure drops of two-row finned tube evaporators [J]. ASME Journal of Energy Resources Technology, 2001,123(1): 100-103.
Wang Chi Chuan, Jang J Y, Lai C C, et al. Effect of circuit arrangement on the performance of air-cooled condensers [J]. International Journal of Refrigeration,1999, 22(4): 275-282.
Domanski P A. Simulation models for finned-tube evaporator and condenser-EVAP-COND 2.1[CP/OL]. Gaithersburg, USA: National Institute of Standards and Technology[2006-08-12].http:∥www2.bfrl.nist.gov/software/evap-cond/.
Domanski P A. Simulation of an evaporator with non-uniform one-dimensional air distribution [J]. ASHRAE Transaction, 1991, 97(1): 793-802.
Domanski P A. Finned-tube evaporator model with a visual interface [C]∥ 20th International Congress of Refrigeration. Sydney,Australia: International Institute of Refrigeration, 1999: 1-7.
Wang Chi Chuan, Chi Kuan Yu, Chang Chun Jung. Heat transfer and friction characteristics of plain fin-and-tube heat exchangers, part II: correlation [J]. International Journal of Heat Mass Transfer, 2000, 43(15):2693-2700.
Thome J R. Update on advances in flow pattern based two-phase heat transfer models[J]. Experimental Thermal and Fluid Science, 2005, 29(3):341-349.
Shah M M. General correlation for heat transfer during film condensation inside pipes [J]. International Journal of Heat Mass Transfer, 1979, 22(4):547-556.
ASHRAE. ASHRAE handbook: fundamentals volume [M]. Atlanta,USA: American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc.,2001: 3-14.
Müller-Steinhagen H, Heck H K. A simple friction pressure drop correlation for two-phase flow in pipes [J]. Chemical Engineering Process, 1986, 20(6):297-308.
Chisholm D. Two-phase flow in pipelines and heat exchangers[M]. London,UK: George Godwin, 1983:304-305.
Idelchik I E. Handbook of hydraulic resistance [M].2nd ed. New York,USA: Hemisphere, 1986: 640-641.