太阳能喷射增效的中高温空气源热泵系统性能分析

Analysis on Performance of Medium-to-High Temperature Air-Source Heat Pump System With Solar Injection Synergy

为进一步研究太阳能喷射增效的中高温空气源热泵系统的性能,建立一维喷射热泵系统热力学模型(高温级以R1234yf为制冷剂,低温级以R245fa为制冷剂).采用能量模型和[火用]模型相结合的方法,研究设计工况的变化对系统性能的影响.研究结果表明:当冷凝温度从45℃升高到70℃时,系统机械效率(COPm)从6.28减小至3.42,以集热量为基准的热效率(COPs)从0.79增大至1.00,以集热器吸收的有效热量为基准的热效率(COPh)从1.55增大至1.95,[火用]效率从20.0%增大至31.8%;当蒸发温度从-20℃升高到0℃时, COPm从4.58增大至5.28,COPs从0.75增大至1.03,COPh从1.46增大至2.02,[火用]效率从23.3%增大至28.9%;当中间蒸发温度从5℃升高到25℃时,COPm从4.33增大至5.14,COPs从1.05减小至0.84,COPh从2.00减小至1.75;当中间蒸发温度为13℃时,系统[火用]效率最大值可达25.7%;在冷凝温度和蒸发温度不变条件下,13℃是较为合理的一个中间温度值.

In order to investigate the system performance of medium-to-high temperature air-source heat pump with solar injection synergy, a 1-D ejector heat pump thermodynamic model was developed(by adoptingthe refrigerant R1234 yf as high temperature circuits and R245 fa as low temperature circuits). The integration of the energy model and the exergy model was deployed to analyze the impact of changeable design conditions on the system performance. The results showed that when the condensing temperature increased from 45 ℃ to 70 ℃, the system mechanical efficiency(COPm) decreased from 6.28 to 3.42, the thermal efficiency based on heat collection(COPs) improved from 0.79 to 1.00, the thermal efficiency based on effective heat absorbed by the collector(COPh) grew from 1.55 to 1.95, and the exergy efficiency enhanced from 20.0% up to 31.8%. While the evaporation temperature raised from-20 ℃ to 0 ℃, the COPm improved from 4.58 to 5.28, the COPs growed from 0.75 to 1.03, COPh increased from 1.46 to 2.02, and the exergy efficiency enhanced from 23.3% up to 28.9%;When the intermediate evaporation temperature increased from 5℃ to 25℃,the COPm improved from 4.33 to 5.14,the COPs reduced from 1.05 to 0.84,and the COPh dropped from 2.00 to 1.75.It is found that the exergy efficiency of the system reached to the maximum of 25.7% when the intermediate evaporation temperature was 13℃.Therefore,the intermediate evaporation temperature was 13℃ with assuming unchangeable conditions of evaporation and condensing temperature.