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通过在FLURENT软件中植入相变UDF模块,实现了对混合工质流动沸腾换热的数值模拟。模拟对象为质量比50/50的CO_2/丙烷混合工质在内径4 mm长1.4 m的光管和微肋管内的流动沸腾换热,工况如下,入口流速为0.487 m/s、入口温度为-5℃、操作压力为2.0928 MPa、壁面热流密度为100 kW/m~2。对比分析了两管内工质的速度分布、温度分布、液相容积分布和流动沸腾换热系数。结果表明,相对于光管,微肋管内工质由于微肋的作用,流速更大,温度更高,气液相分界面出现更早,对流换热系数更大,即微肋管内CO_2/丙烷混合工质的沸腾换热被强化。
By embedding phase change UDF module in FLURENT software, the numerical simulation of the flow boiling heat transfer of mixed working fluid is realized. The simulated object was the flow boiling heat transfer of CO_2 / propane mixed medium with a mass ratio of 50/50 in a light pipe and a microtube tube with an inner diameter of 4 mm and a length of 1.4 m. The working conditions were as follows: the inlet flow rate was 0.487 m / s, -5 ℃, the operating pressure is 2.0928 MPa and the wall heat flux is 100 kW / m ~ 2. The velocity distribution, temperature distribution, liquid volume distribution and flow boiling heat transfer coefficient were compared and analyzed. The results show that due to the effect of micro-ribs, the working fluid in the microtube tube has larger flow velocity and higher temperature, the interface of gas-liquid phase appears earlier, and the convection heat transfer coefficient is larger, that is, the CO_2 / propane Boiling heat of mixed refrigerant is strengthened.