R22替代工质蒸发器的性能研究

Numerical Study of Heat Transfer and Flow Characteristics in R22 Refrigerant Replacement Evaporators

基于湿球温度效率法,建立了蒸发器的稳态分布参数模型。分别以R22及其3种替代产品(R407C,R410A,R134A)为工质,运用该模型详细比较了在流量变化及风量变化两种情况下2排管蒸发器的换热和流动特性。结果表明:当迎风面风速不变时,随着管内冷媒流量的增大,各种工质蒸发器总换热量、显热换热量、潜热换热量均增大,但潜热换热量增大得更快。压降亦随着管内流量的增大而增大。当管内冷媒流量不变时,随着蒸发器迎风面风速的增大,各种工质蒸发器总换热量、显热换热量均增加,潜热换热量下降,同时压降亦下降,但下降的趋势随着风速的增大而最终趋于平缓。四种工质中,R134A性能较好,但其压降也最大,R410其次,压降最小,但其蒸发压力比R22高出60%左右。R407C与R22在换热量及压降方面最为接近,是其理想的替代产品。

Based on the ε_c-BF, a steady state distributed parameters model is put forward in the numerical simulation of refrigerant circuitry in evaporators in this paper. Applying this model, the heat transfers and flow characteristics of two-rows counter-flow evaporators which used the refrigerant replacement of R22 (R407C, R410A, R134A) are studied. When the frontal velocity is constant, with the refrigerant mass velocity increasing, the total capacity, sensible capacity , and the latent capacity of all evaporators which apply different refrigerants increase, the pressure drop in tubes decrease. When the refrigerant mass velocity is constant, with the frontal velocity increasing, the total capacity, sensible capacity of all evaporators which apply different refrigerants increase and the latent capacity, pressure drop in tubes decrease. Among the characteristic comparison of four refrigerants evaporators, the heat transfer rate of R134A evaporators is better than the other refrigerants evaporators, but its pressure drop is the highest. The heat transfer rate of R410A evaporators is better than R22 evaporator, but the evaporate pressure much higher than that of R22; both of the two refrigerant replacement are not the perfect replacements. The heat transfer rate of R407C evaporators is 3%～5% higher than R22 evaporators and the pressure drop of R407C evaporators is 5%～10% lower than R22. R407C is the ideal refrigerant replacement of R22.