翅片间距对两流路双排管蒸发器换热影响分析

Analysis of the influence of fin spacing on heat transfer performance of double-row tube evaporator with two circuits

翅片管蒸发器换热性能直接影响制冷空调机组能效,调整翅片间距是增大换热面积、改进换热效果的有效途径。文章建立了翅片管蒸发器的流体流动简化模型,利用EVAP-COND软件模拟了外掠气流中三角风速分布工况下,不同翅片间距对两流路双排管蒸发器换热性能的影响。结果表明:翅片间距越大,蒸发器的换热量越小,翅片间距为1.75、2.00、2.25、2.50 mm时的换热量分别比1.50 mm时减小了4.4%、9.02%、14.1%和18.2%;翅片间距越大,制冷剂流量就越小,蒸发器的总换热量也就越小;蒸发器中显热比随翅片间距的增大而降低,综合考虑空气阻力损失及换热,翅片间距为2.00 mm较为合理;不同翅片间距工况下,制冷剂在不同支路每根管内吸热对外掠空气降温影响与换热量一致。

The heat transfer performance of finned tube evaporator directly affects the energy efficiency of refrigeration and air conditioning units,while the effective way to improve the heat transfer effect is to increase the heat transfer area by adjusting the spacing of fins.In this paper,a simplified fluid flow model for finned tube evaporator is established and the effect of different fin spacing on the heat transfer performance of double-row tube evaporator with two circuits was simulated under the condition of triangular wind speed distribution in the external swept flow by the software EVAP-COND.The results show that the larger the fin spacing is,the smaller the heat transfer of the evaporator will be.The fin spacing of 1.75,2.00,2.25 and 2.50 mm will decrease 4.4%,9.02%,14.1%and 18.2%,respectively,compared with 1.5 mm.The greater the spacing of fins,the smaller the refrigerant flow,the smaller the total heat transfer of the evaporator.The sensible heat ratio in the evaporator decreases with the increase of fin spacing.Considering the loss of air resistance and heat transfer,the fin spacing of 2.0 mm is more reasonable.Under the different conditions of fin spacing,the cooling effectt of external swept airof heat absorption of refrigerant in each tube of different branches is consistent with that of heat exchange.