采用两段式引射器的跨临界CO_2两相流制冷系统性能的数值模拟

Numerical Simulation on Performance of Two-Phase Ejector Refrigeration Cycle With A Two-Throat Nozzle Ejector

对两相流引射器内部工质流动特性进行了数值模拟,通过在不同几何尺寸和不同工况条件下引射器性能分析来确定影响其性能的因素。分析了两段式喷嘴引射器在不同第一喉部流通面积和不同工况条件下的性能,以及两段式喷嘴引射制冷系统性能随着各参数的变化趋势:在固定气冷器出口压力9.00 MPa,温度43℃和蒸发温度6℃条件下,两段式喷嘴引射器性能随着第一喉部流通面积的增加先增大后减小,并在第一流通面积为1.54 mm2时取得最大引射比;当两段式喷嘴引射器第一喉部流通面积为1.54 mm2时,在模拟工况范围内引射器的引射比随着气冷器出口温度的增加而增大,随着蒸发温度的降低而减小;当气冷器出口压力和蒸发温度分别为9.00 MPa和6℃时,引射器的引射比在气冷器出口温度为43℃工况下取得最大值。

In this paper, the internal flow characteristics of the two phase flow ejector were simulated numerically, the performance of the ejector and the transcritical CO2 refrigeration system with different geometric size of ejectors under different working conditions were compared to find the affecting factors of the two phase flow ejector. The effects of cross-sectional area of the first nozzle throat and working conditions on the performance of the dual-throat nozzle ejector were analyzed. The conclusions as follow： under the working condition of fixed gas cooler outlet pressure/temperature 9.00MPa/43℃ and evaporating temperature 6℃, the numerical simulation a results indicates that the performance of the dual-throat nozzle ejector firstly increases and then decreases with the increases in the cross-sectional throat area of the first nozzle, the entrainment ratio of the dual-throat nozzle ejector achieves the maximum as the across-sectional throat area of the first nozzle is 1.54 mm2 ; The simulation results indicates that the entrainment ratio of the dual-throat nozzle ejector increases with the increase in the gas cooler outlet temperature and decreases with the increase in the evaporating temperature as the cross-sectional throat area of the first nozzle is 1.54 mm^2. Under the working condition of fixed gas cooler outlet pressure/evaporating temperature 9.00MPa/6℃, the entrainment ratio achieves the maximum as the condensing temperature is about 43℃.