Optimization of evaporator structure in a direct expansion solar heat pump
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摘要: 对直膨式太阳能热泵系统中集热/蒸发器结构进行研究，建立吹胀板集热/蒸发器分布参数的数值模型，利用试验数据对模型进行可靠性验证，模拟分析管道流程管数排布、管间距对集热/蒸发器板的集热效率以及热泵系统性能系数(coefficient of performance, COP)的影响。结果表明，在总管数一定的条件下，第一、二流程管数比增大，制冷剂总压降越低，蒸发温度越高；管数比为1∶1时集热效率与COP最佳。随管间距的增大，集热效率与COP先增大后减小，管间距在0.04 m时达到最佳值。Abstract: The optimization of the collector/evaporator structure in a direct-expansion solar heat pump system was investigated. A distributed parameter numerical model for a roll-bond collector/evaporator was developed and validated against experimental data. The effects of the path tube number arrangement and tube spacing on the collector/evaporator collector efficiency and the coefficient of performance (COP) of the heat pump system were simulated and analyzed. The results indicate that, for a given total number of tubes, a larger tube number ratio between the first and second paths can lead to a lower total refrigerant pressure drop and a higher evaporation temperature. The optimal heat collection efficiency and COP are achieved when the tube number ratio is 1∶1. Furthermore, as the tube spacing increases, both the heat collection efficiency and COP first increase and then decrease, reaching their maximum values at a tube spacing of 0.04 m.
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Key words:
- solar energy /
- collector/evaporator /
- tube spacing /
- path arrangement /
- numerical simulation
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图 1 直膨式太阳能热泵热水器原理图
Figure 1. Schematic diagram of direct expansion solar heat pump water heater
图 7 试验与模拟COP对比
Figure 7. Comparison of COP between experimental and simulation results
图 8 试验集热/蒸发器表面温度分布
Figure 8. Experimental collector/evaporator surface temperature distribution
图 9 模拟集热/蒸发器表面温度分布
Figure 9. Simulation of surface temperature distribution on collector/evaporator
图 12 制冷剂平均温度与过热区面积的变化
Figure 12. Variation of average refrigerant temperature and area of superheated zone
图 14 不同管间距时COP随管数比的变化
Figure 14. Variation of COP with ratio of tube numbers at different tube spacings
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