相对湿度对空调中翅片管蒸发器性能的影响

Effect of relative humidity on the performance of finned-tube evaporator in air-conditioning

基于换热器几何结构参数以及流路布置等相同的3HP商用空调,在空调工况下,研究了相对湿度对R22替代制冷剂R407C、R410A、R32以及R290在蒸发器内的流动和传热性能的影响规律。研究表明:在一定的条件下,增加环境相对湿度,这五种制冷剂对应蒸发器换热量、压降和质量流量均增加,其中R407C蒸发器换热量最大,R290和R32蒸发器压降和制冷剂质量流量均小于R22蒸发器。在低湿度环境下(约20—30%相对湿度),显热换热占主导因素。随着相对湿度的增加,显然换热减少,潜热换热增强且起主导因素。在满足换热量的要求下,R290在协调压降与质量流量具有一定的优势且满足现行工质替代理念,可以作为现有商用空调的环保型替代工质。

Based on the same geometrical parameters, circuitry arrangement and so on, the characteristics of alternative refrigerants R407C,R410A,R32 and R290 to R22 in finned - tube heat evaporator of 3HP commercial air conditioning system are investigated under air conditioning operating condition. The effects of different relative humidity on the flow and heat transfer performance of evaporators are analyzed. The resuhs show that all of the heat flux,pressure drop and the mass flow rate of the five alternative refrigerants increase with increased relative humidity of the ambient under certain conditions. R407C obtains the largest heat flux. Both the pressure drop and the mass flow rate of refrigerants R290 and R32 are lower than that of R22. Under the lower relative humidity ranged from 20% to 30%, the heat flux of sensible heat becomes the dominant factor governing the evaporator capacity. Both the sensible heat and latent heat increase with increased relative humidity, and the heat flux of latent heat acts as the dominant factor. Overall, when the heat flux of the system is contented, the results demonstrate that R290 has the particular advantages in terms of harmonizing the pressure drop with the mass flow rate, and is also in line with the present ideas of alterna- tive refrigerants. It can be used as environment friendly alternative refrigerant for commercial airconditioning.