Passive heat transfer enhancement techniques applied to compact bubble absorber design

This paper presents performance results and analysis for three compact bubble absorbers developed for generator-absorber heat exchange absorption cycles (GAX). The absorbers employ passive heat transfer enhancement techniques, namely repeated roughness, spiral flutes, and internal spacers. The selection of enhancement techniques was done after a controlling heat transfer resistance analysis of a baseline absorber was completed. Experimental results showed that the enhancement increased the GAX load, increased the vapor flow rate, and decreased the approach temperature difference when compared to the baseline values. However, the performance of each enhanced absorber remained below design goals. Both the vapor injection process and the interior heat transfer coefficient calculation methodology need further improvement to reach design goals.