高效换热的CO_2水源热泵系统的实验研究

EXPERIMENTAL STUDY OF CO_2 WATER SOURCE HEAT PUMP USING HIGHLY EFFECTIVE HEAT EXCHANGERS

为进一步提高跨临界CO2水源热泵系统的效率，对原有试验台进行改造，建立新的CO2水源热泵系统。新的水源热泵实验台采用新型套管式蒸发器和气体冷却器。在实验中考虑气体冷却器进水温度分别为15、20、25℃3种工况，对CO2水源热泵提供温度为45～70℃热水时系统的性能进行分析。结果发现，采用新型换热器可使热泵系统效率提高。气体冷却器进水温度越低，热泵系统的制热效率越高。降低冷却器出口工质的温度有助于提高系统的制热效率。相同的进出水温度下存在较优的蒸发温度。制取的热水温度越高，热水的质量流量越低。

Studies showed that heat transfer effect of heat exchangers had great impact on the heat pump system. In order to improve the efficiency of the water-source heat pump system using CO2 as refrigerant, a new water-source heat pump was built up on the basis of the original one. The new heat pump uses newly-designed double-pipe evaporator and gascooler. Experiments were done under three working conditions, namely, the inlet water temperatures of gascooler were 15℃, 20 ℃ and 25℃ respectively; and the performance of the system was analyzed when the outlet water temperature ranged from 45 ℃ to 70 ℃. Test outcomes indicated that the use of newly-designed heat exchangers improved the efficiency of the system. The lower the inlet water temperature of the gascooler is, the higher the COPh is. The lower outlet CO2 temperature of the gascooler can increase the COPh. The optimum evaporation temperature occurs at same inlet-and outlet-water temperatures of gascooler. The higher the outlet water temperature is, the lower the mass flow rate is.