CO_2双缸滚动活塞膨胀机Fluent模拟与分析

Fluent Simulation and Analysis of CO_2 Two-Cylinder Rolling Piston Expander

研究用双缸滚动活塞膨胀机代替节流阀,以提高CO2跨临界循环的效率.为了更清楚地研究CO2双缸滚动活塞膨胀机的工作情况,对其工作时内部的压力场、不同长径中间通道的压力场和湍流强度场进行了Fluent模拟与分析,压力场分析结果可以看出膨胀前后容积并非完全等于一级气缸和二级气缸的容积,还应加上中间通道的容积.不同长径中间通道分析结果指出长度20,mm、直径4,mm的中间通道所造成的压力损失最小.湍流强度分析结果显示湍流强度波动主要集中在二级气缸进气口的月牙形空间处,一级气缸的流体流动则相对稳定,湍流强度较低.

Two-cylinder rolling piston expander in place of throtting valve has been studied in this paper to promote the efficiency of CO2 transcritical cycle. This paper simulates and analyzes inner pressure field, inner pressure field of different intermediate channels and turbulence intensity when two-cylinder rolling piston expander works in order to fully understand the expander. The result shows that the volume of expansion from start to finish is equal to the total volume of the first and the second cylinders and intermediate channel. During the simulation, the intermediate channel with the length of 20 mm and the diameter of 4 mm has the least pressure loss. This paper also concludes that the turbulence intensity fluctuation mainly concentrates in the half moon-shape space of the second cylinder while the flow in the first one is comparatively stable. These conclusions will offer help to the further study of the inner fluxion condition of the expander.