Speaker
Description
In refrigeration applications, hydrocarbons have high thermodynamic performances and belong to the group of natural refrigerants. Especially in mixture Joule-Thomson low temperature refrigerators (MJTR), hydrocarbons (methane, ethane, propane and butane) are the main components and have acquired wide applications.
A brief literature survey is made on the flow condensation study of hydrocarbons. The principal experimental work in the literature is described. Then, a description of widely quoted flow condensation heat transfer prediction methods is presented. Since there are few specific prediction methods for hydrocarbon, five flow condensation heat transfer prediction model were selected to compare to the experimental data from the available studies. The comparisons only focus on flow condensation in plain tubes.
Based on the basis of the comparisons and analysis, a new flow condensation heat transfer model based on the flow condensation heat transfer mechanisms for horizontal tubes have been developed specifically for hydrocarbons. Firstly, a new evaluation of condensation contribution in flow condensation heat transfer has been proposed for hydrocarbons. Secondly, a new correlation for the factor describing the contribution of condensation has been proposed based on the condensation heat transfer mechanisms. It incorporated the influence of liquid film thickness and vapor quality. Thirdly, a forced convection heat transfer enhancement factor correlation incorporating liquid velocity has been proposed based on the convective heat transfer mechanisms so as to capture the trends in the flow condensation heat transfer data. In addition, the comparisons of the new model and other classic models, as well as the comparison of experimental values and predicted values for low-boiling hydrocarbons, were made to evaluate the accuracy of the new heat transfer model.
