辐射强度对直膨式太阳能热泵系统性能的影响

为分析太阳辐射对直膨式太阳能热泵系统性能的影响,研究了变频控制的R134a直膨式太阳能热泵热水器系统。对典型冬季试验中不同太阳辐射强度下的系统性能和关键参数进行讨论。试验结果表明,吸气过热度和系统COP(coefficient of performance)值都随太阳辐射强度的增加有不同程度的增加,压缩机平均排气温度则略有下降。在相似的环境温度下,当辐射由233 W·m^-2增至631 W·m^-2时,系统COP由3.39增至4.31,相对增加了28.9%。同时,集热器集热效率与太阳辐射强度呈现负相关的关系,太阳辐射越强,集热器集热效率越低。当有效集热面积为2.10 m²,太阳辐射强度由233 W·m^-2增加到631 W·m^-2时,集热效率由2.17减小到0.9,降低了58.5%。

Influence of performance of direct-expansion solar-assisted heat pump system at different solar radiation intensity

To analyze the effect of solar radiation intensity on direct-expansion solar-assisted heat pump system (DX-SAHP), a direct-expansion solar-assisted heat pump water heater (DX-SAHPWH) system using variable frequency control and R134a was introduced and studied in this research. By carrying out the experiments under typical winter meteorologic conditions, the system performance and critical parameters were discussed. It revealed that the increasing solar radiation intensity made a higher superheat degree and coefficient of performance (COP), while the discharge temperature decreased with it. At similar ambient temperature, when the solar radiation intensity increased from 233 W·m^-2 to 631 W·m^-2, the system COP varied from 3.39 to 4.31, increased by 28.9%. Meanwhile, the solar radiation intensity had an opposite effect on the solar efficiency, which meant the higher solar radiation intensity was, the smaller collector efficiency was. Based on collector area of 2.10 m², the solar collector efficiency decreased from 2.17 to 0.9 with the rising solar radiation intensity from 233 W·m^-2 to 631 W·m^-2, decreased by 58.5%.