冷风机在结霜工况下的传热及压降特性的研究

Study on heat transfer performance and pressure drop characteristics of chiller under frosting conditions

速冻设备用冷风机由于需要对大量的冷库进库食品进行快速降温,在此期间,结霜量较多,对换热器的性能影响较大。为探究不同结霜工况换热性能的变化,进行了实验研究。该实验采用空气侧焓差法对换热器的性能进行研究,采用压降计测量压降特性。实验结果表明:-10℃结霜工况下,换热系数经八次加湿由干工况的27.7W m2(·K)下降到5. 7W m2(·K),下降速度逐渐减缓。-25℃结霜工况下,换热系数经八次加湿由干工况的29.4W m2(·K)逐渐下降到8. 4W m2(·K)。该次实验有效地测试了换热器在结霜工况的换热系数,为除霜和提高换热系数提供了参考。

Because a chiller for quick - freezing equipment needs to cool a large amount of food in the cold storage, the frost develops so fast that it has a great influence on the performance of the air cooler. So in order to test the heat transfer performance of air cooler under different frosting conditions, the experimental study was carried out. In this experiment, the enthalpy potential method was used to calculate the heat transfer performance of air cooler, and the pressure drop meter was used to measure the air pressure drop. The results show that when the inlet air temperature is -10℃, the heat transfer coefficient decreases from 42. 23W/（ m^2·K） to 8.67W/（ m^2·K）, and the decreasing rate gradually becomes slow. When the inlet air temperature is - 25℃, the heat transfer coefficient decreases from 47.82W/（ m^2·K） to 16.18W/（ m^2·K） gradually. This heat transfer performance of the air cooler was tested under different frosting conditions, which could provide a reference for defrosting and improving the heat transfer coefficient.