The Influence Of Different Static Pressure Box Coefficients And Humidity On Frosting Of Air Cooler

When the temperature of the cold surface of the air cooler is reduced below the triple point keeping a certain degree of subcooling,The team condenses directly into solids attached to the cold surface,however,frosting will have a detrimental effect on the heat transfer of the air cooler.In this experiment,the frost volume and frost rate of the chillers were analyzed by changing the coefficient of the static pressure box(the ratio of the distance between fan and fin to the diameter of the fan)and the humidity.The selected coefficients of the static pressure box respectively are 0.74,0.97,1.2.The initial conditions are respectively high humidity environment(room temperature of 22 ?,relative humidity of 88%,humidification)and low humidity environment(room temperature of 22 ?,relative humidity of 65%,no humidification),measure the thickness variation of the frost on the selected measuring point under different operating conditions.And Comsol simulation as a supplement to the experiment was mainly for the calculations of some special points and surface,make up for the shortcomings that some areas cannot be measured due to limited conditions.At the same time the experimental measurements also could verify the accuracy of the simulation.The study found:1.Under different coefficients of static pressure box,there was a big difference in the amount of frost.The maxmum value of volume would be got when the coefficient of static pressure box was 0.97,moreover,when the coefficients of static pressure box were 0.74 and 0.97,the difference of the frost volume was obviously less than that when the coefficients of the static pressure box were 0.97 and 1.2,and the difference would decrease first and then increase.2.Under different coefficients of static pressure box,the frost growth curve at the measuring point of the evaporating tube and the finshowed a different growth trend under the condition of high humidity and humidification,the growth rate of frost layer on the evaporating tube increased with the increasing of the static pressure box coefficient,however,the fin appeared to increase first and then decrease;under the condition of low humidity and no humidification,the growth rate of frost layer on the evaporating pipe had little relation with the static pressure coefficient,and the thickness of frost layer on the fin also increased first and then decreased with the increasing of the coefficient of the static pressure box.3.The results of simulation and the experiment had high consistency verifying the feasibilityof the established simulation model(located in the first half of the fin and evaporation tube regarded as frost-free,the latter half regarded as differential ladder cream layer),at the same time the simulation results could be used to quantify and analyze the phenomena in the experiment.4.For the measuring points,the coefficient change of the static pressure box mainly depended on the change of inlet velocity,which caused the huge differencesof the amount of frostoverall at the measuring points,as well as the big changes of the frost rate of the evaporation tubes and fins,high humidity had greater significantlyeffect on the evaporation tube than that on the fin,under low humidity,however,the opposite results occurred.5.The finsand evaporating tubes at the inlet side of the air cooler mainly formed ice,which is due to the great humidity at the inlet side and the high temperature,the tubes on the back row basically frost because the front row tubes cooled the moist air and the temperature of the evaporating tube was low.