Theoretical and Experimental Investigation for Optimal Discharge Pressure of Air-Source Trans-Critical CO2 Heat Pump[J]. 2014, 48(9): 81-87. DOI: 10.7652/xjtuxb201409014.
DOI:
Theoretical and Experimental Investigation for Optimal Discharge Pressure of Air-Source Trans-Critical CO2 Heat Pump[J]. 2014, 48(9): 81-87. DOI: 10.7652/xjtuxb201409014.DOI:
Theoretical and Experimental Investigation for Optimal Discharge Pressure of Air-Source Trans-Critical CO2 Heat Pump
To reveal the main factors of the optimal discharge pressure in a trans-critical CO
2
heat pump system
the heating performance is tested in enthalpy difference laboratory. The results show that the evaporation pressure and temperature in gas-cooler outlet decline with increasing discharge pressure; the superheat increases with discharge pressure; the heating capacity and the coefficient of performance(COP)increase firstly and then drop when discharge pressure rises
indicating that an optimal value exists. According to the test data
it is found that the optimal discharge pressure drops with declining environment temperature
inlet water temperature and outlet water temperature. At un
changed inlet water temperature(ambient water temperature)
an experimental correlation taking environment temperature and outlet water temperature as independent variables is constructed by data fitting to predict the optimal discharge pressure. The experiments indicate that the COP difference between predicted optimal discharge pressure and actual optimal discharge pressure is less than 1.3%.
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references
LORENTZEN G. Trans-critical vapour compression cycle device: Switzerland, WO 90/07683[P]. 1990-07-12.
LORENTZEN G, PETTERSEN J. A new, efficient and environmentally benign system for car air-conditioning[J]. International Journal of Refrigeration, 1993, 16(1): 4-12.
KAUF F. Determination of the optimum high pressure for transcritical CO2 refrigeration cycles[J]. International Journal of Thermal Sciences, 1999, 38: 325-330.
LIAO S M, ZHAO T S, JAKOBSEN A. A correlation of optimal heat rejection pressures in transcritical carbon dioxide cycles[J]. Applied Thermal Engineering, 2000, 20: 831-841.
SARKAR J, BHATTACHARYYA S, GOPALM M R. Optimization of a transcritical CO2 heat pump cycle for simultaneous cooling and heating applications[J]. International Journal of Refrigeration, 2004, 27: 830-838.
CHEN Y, GU J. The optimum high pressure for CO2 transcritical refrigeration systems with internal heat exchangers[J]. International Journal of Refrigeration, 2005, 28: 1238-1249.
GE Y T, TASSOU S A. Control optimization of CO2 cycles for medium temperature retail food refrigeration systems[J]. International Journal of Refrigeration, 2009, 32: 1376-1388.
CECCHINATO L, CORRADI M, COSI G, et al. A real-time algorithm for the determination of R744 systems optimal high pressure[J]. International Journal of Refrigeration, 2012, 35(4): 817-826.
LIN Gaoping, GU Zhaolin. Performance of Super-critical CO2 refrigeration cycle[J]. Journal of Xi'an Jiaotong University, 1998, 32(8): 35-38.
SÁNCHEZ D, TORRELLA E, CABELLO R, et al. Influence of the superheats associated to a semi-hermetic compressor of a transcritical CO2 refrigeration plant[J]. Applied Thermal Engineering, 2010, 30: 302-309.
ZHANG X P, FAN X W, WANG F K, et al. Theoretical and experimental studies on optimum heat rejection pressure for a CO2 heat pump system[J]. Applied Thermal Engineering, 2010, 30: 2537-2540.