Prediction model of flow boiling heat transfer in microfinned hydrophobic composite enhanced tube
The flow boiling heat transfer characteristics of the refrigerant in one smooth tube(ST tube)and three enhanced tubes were compared experimentally.The three enhanced tubes used in the experiment are respectively the heat transfer tube with hydrophobic surface(HYD tube),the heat transfer tube with herringbone microfin(HB tube)and the heat transfer tube with the composite structure of herringbone microfin and hydrophobic surface(HB/HYD tube).The experiments were carried out at saturation temperatures of 279,283 and 288 K,mass flux ranging from 50 kg/(m2·s)to 150 kg/(m2·s),and inlet and outlet vapor quality maintained at 0.2 and 0.8,respectively.It can be seen from the analysis of the results that the average heat transfer coefficient of HB tube and HYD tube is about 1.37 and 1.42 times that of smooth tube,respectively,the HB/HYD tubes with composite surface structure have the highest heat transfer coefficient,about 1.45-1.63 times that of smooth tube.According to the measured heat transfer coefficient,six empirical prediction correlation models are selected and verified by smooth tube,which proves the reliability of the selected correlation models.Combined with the structural characteristics of the enhanced tubes,a new correlation model is developed,which can predict the heat transfer coefficient of the studied enhanced tubes well.About 90％of the data points of the three enhanced tubes are within the error range of±10％,this optimizes the scheme of industrial design of heat exchanger,thereby improving the efficiency and reliability of heat exchanger.
phase changegas-liquid flowflow boilingheat transferprediction model
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