BG1-8 Heat Transfer in Boiling of Multicomponent Mixtures
This report is an extension of the work presented in HTRI Report BG1-7 which described the first HTRI data for the effects of number of components on the mixture correction for pool boiling of multicomponent mixtures.
The original method was based on only two fluids, and it was decided to test three additional mixtures. Results presented in this report show that the basic method developed in Report BG1-7 can also predict the effect of number of components on the mixture correction for these new data, and therefore can be considered a viable correlation for design use.
Another result presented in this report is the extension of the Schlünder film theory method to multicomponent fluids by use of a boiling range substitution first proposed by Thome and Shakir. It was possible to further improve this method by use of the above-mentioned HTRI multicomponent correction and by use of a newly correlated expression for the mass transfer coefficient so that prediction was about equal to that of the latest HTRI Boiling Range Method. Both methods were compared against fifteen data cases with 13 to 28 data points each and both predicted most of the data within ± 25% with standard deviations of about 15 percent.
As an additional side study, a new method was developed to handle cases with a large amount of light component and small amount of very heavy component, termed the “rocks” case. This new procedure is more logical than the previous and gives better results.
In general it was concluded that the methods developed in HTRI Report BG1-7 are confirmed as they stand (with one minor change in recommended procedure). In addition, it is concluded that the new modified Schlünder method (including both Thome and HTRI modifications) produces good results for pool boiling of hydrocarbon mixtures over a very wide range and is recommended, at least as an alternate approach.
Recommendations are given for future research, including analysis of new data for boiling mixtures at high pressures, and a beginning basic study on flow boiling of wide-boiling-range mixtures.