Characterization of the Pressure Drop during Condensation in Channels of Multi-Channel Cylinder Dryer Using Homogeneous and Separated Flow Models

Abstract

The condensation resistance characteristics of steam flow in horizontal rectangular channels of multi-channel cylinder dryer (MCD) is a very important factor that affects the heat transfer, while it is not very clear due to the limited studies. In this paper, the frictional resistance characteristics of the two-phase flow (steam and water) in the rectangular small channels of MCD were investigated with deionized water as the working fluid, and the calculation models, homogeneous and separated flow models, of the two-phase flow pressure drop in the channel were verified and evaluated. It showed that the main part of the total pressure drop was the frictional pressure drop, which means that the calculation of frictional pressure drop was the key to the calculation of the pressure drop of the two-phase flow in the channel. Meanwhile, it was found that the homogeneous model was not suitable for the calculation of the frictional pressure drop and the separated flow model was completely in line with the experimental data. In this study, the converted coefficient of complete steam/liquid phase were concerned to calculate the frictional resistance using five separated flow models. It was found that the Chisholm B model showed better accuracy than prior correlations, which was greatly consistent with experimental data, and the average absolute percentage deviation (MAPE) was 24.9%.