喷射器临界背压对喷射制冷系统性能的影响

为了确保喷射器在良好的工况条件下运行,文中针对太阳能喷射制冷系统的工况范围,以R134 a为工质建立了喷射器运行特性计算模型,计算分析了临界背压随喷射器运行工况的变化关系,以及对制冷系统性能的影响。结果表明:喷射器的临界背压随发生温度和蒸发温度的增大而增大,极限喷射系数随发生温度的升高而降低,随蒸发温度的升高而升高;喷射制冷系统COP随喷射器背压(冷凝压力)的升高先保持不变后减小,当Tg=353K,Te=281K和Te=283K时,喷射器分别在Tc=307K左右和Tc=308K左右时,达到临界状态,临界背压分别为0.85MPa、0.88MPa,COP分别为0.2和0.227。

Effect of ejector critical downstream pressure on the ejection refrigeration system

In order to make an ejector work better,a model for predicting the ejector operation features was established based on the solar ejection refrigeration system used R134a as refrigerant,which could be applied to analyze the relation between ejector critical down stream pressure and operational mode as well as its influence to the ejection refrigeration system.It was found that the critical down stream pressure increased with the evaporation and generation temperature,critical entrainment ratio of an ejector increased with the evaporation but decreased with generation temperature,the refrigeration system COP value at first kept almost constant until the critical value and then reduced with the down stream pressure.COP could reach as high as 0.227 and usl=0.33 at Tg=353K,Te=283K,and the critical back pressure for ejector was 0.88MPa,and the critical back pressure for ejector was 0.85MPa when Tg=353K,and Te=281K.