蒸汽喷射式热泵变工况性能分析

Analysis of the Off-design Performance of Steam-jet Heat Pumps

采用数值模拟的方法对低压蒸汽增压利用系统中的蒸汽喷射式热泵在非设计工况下的操作性能进行研究,计算并分析了工作蒸汽压力和温度、引射流体压力及混合流体压力等热力参数对热泵操作性能的影响。数值结果表明:当混合流体的压力低于一定的数值时,喷射系数维持一定值;而热泵对引射流体压力的变化极为敏感,引射压力的微小变化可能导致热泵操作性能的急剧下降;提高工作蒸汽的压力并不一定能改善喷射泵的工作性能,这是因为提高工作蒸汽压力会增加额外的蒸汽量所致;喷射系数随工作蒸汽温度的升高而略有增大,并近似呈线性率。

By using a numerical simulation method the off design operating performance of steam jet pumps in a low pressure steam utilization system was studied and calculated. In addition, an analysis was conducted of the impact of such parameters as the operating steam pressure and temperature, the pressure of jet flows and mixed fluids on the operating performance of the heat pumps. The results of the analysis indicate that when the pressure of the mixed fluids is lower than a certain value the ejection factor can be maintained at a definite value. The heat pumps are very sensitive to the change of ejection fluid pressure. A minor change in the ejection pressure can lead to a drastic reduction in the heat pump operating performance. An increase in the operating steam pressure will not necessarily improve the performance of the steam jet pumps. This is because an increase in the operating steam pressure will lead to a greater steam flow. The ejection factor will slightly increase with a rise in steam temperature and this variation assumes an approximately linear character.