蒸发器流程布置的数值模拟研究与分析

Numerical Simulation and Study of Refrigerant Circuitry in Evaporator

基于湿球温度效率法,建立了蒸发器的稳态分布参数模型,分析了三种不同流路布置蒸发器的换热性能,并与前人的实验研究结果进行对比,计算所得的换热量与试验值的最大偏差为9.44%,说明该模型切实可行。运用该模型计算并分析了六种不同流路布置蒸发器的流动和换热特性,结果表明:逆流布置蒸发器换热最好,错流其次,顺流最差。各种流路布置方案管外迎风面风速不变时,随着管内冷媒流量的增大,管内压降、总换热量、显热换热量、潜热换热量均增大,但潜热所占比重增大。管内冷媒流量保持不变,蒸发器迎风面风速增大时,总换热量、显热换热量均增大,潜热换热量、压降、吸湿系数均减小;当风速增大到一定程度时,蒸发器换热量、压降的变化都趋于平缓。同时,在蒸发器流路布置中,重力的影响不可忽略。研究结论为蒸发器流程布置的优化设计提供了理论基础和指导方向。

Based on the Ec - BF, a steady state distributed parameters model was presented for the numerical simulation of refrigerant circuitry of evaporators. The heat transfer of evaporators with three different arrangements was analyzed. The results of heat transfer capacity calculations are coincident with the experiment results in the previous literature. Applying the present numerical model, the characteristics of flow and heat transfer for evaporators with six different arrangements were studied. The simulation results indicate that the counter - flow arrangement evaporator has a petter performance than other arrangements evaporators, and the parallel - flow is the worst and mix - flow is in the middle. When the face velocity is constant, with the increase of the refrigerant mass velocity, the total capacity, the sensible capacity, the latent capacity, and the pressure all increase, but the proportion of the latent capacity is larger than that of the sensible capacity to the total capacity. When the refrigerant mass velocity in the tubes is constant, with the increase of the face velocity, the total capacity and sensible capacity increase while the latent capacity and the pressure decrease. When the face velocity reaches a certain value, the total heat transfer capacity and the pressure will keep constant. In addition, the influence of gravity force can not be ignored in the design of the refrigerant circuitry arrangement in evaporators.