膨胀机与喷射器跨临界二氧化碳循环比较研究

Comparative Study on the Transcritical Carbon Dioxide Cycle with Expander and Ejector

减少跨临界二氧化碳热泵循环高压截流损失的方案主要有膨胀机和喷射器两种。建立了跨临界二氧化碳节流阀循环模型、膨胀机循环模型和喷射器循环模型。研究了在典型的家用热泵热水器工况下采用不同循环时,气体冷却器工质进出口温度对循环性能和高压侧压力的影响。研究结果表明,气体冷却器工质出口温度低于40℃时,膨胀机循环效率高于喷射器循环;气体冷却器工质出口温度高于40℃时,膨胀机循环效率低于喷射器循环;膨胀机循环与截流阀循环的高压侧压力相同,低于喷射器循环。

The methods to decrease the high pressure throttling loss in transcritical carbon dioxide heat pump cycle include expander and ejector. The transcritical carbon dioxide cycle models with a throttling valve, with an expander and with an ejector were developed. The effect of gas cooler outlet temperature and inlet temperature of the carbon dioxide on the cycle performance and discharge pressure was investigated. The calculation result shows that when the gas cooler outlet temperature of the carbon dioxide is below 40℃, the performance of expander cycle is higher than that of the ejector cycle; when the gas cooler outlet temperature of the carbon dioxide is above 40℃, the performance of expander cycle is lower than that of the ejector cycle; the discharge pressures of the expander and throttling valve are same, and are lower than that of the ejector cycle.