Experimental parameter study and correlation development of microchannel membrane-based absorption process for efficient thermal cooling with high compactness

Abstract

The microchannel membrane-based absorber occupies a crucial position in an efficient and compact absorption refrigeration system, as it directly influences the system's cooling capacity. However, existing numerical models for describing the absorption process of this absorber often exhibit large deviations, as they are adopted from other processes. To establish highly accurate correlations, extensive experiments are performed in this study to evaluate the absorption process using H2O/LiBr as the working fluids across a wide range of operating conditions. The experimental results demonstrate that enlarging the solution flow rate, vapor pressure, and solution concentration or lowering the cooling water temperature can improve the heat and mass transfer processes significantly. By analyzing the experimental results, new correlations of Nusselt number (Nu), Sherwood number (Sh), and friction factor (f) are developed for heat/mass transfer and solution pressure drop, respectively. It is verified that these newly developed correlations significantly enhance the prediction accuracy of the overall heat transfer coefficient (U), absorption rate (J), and pressure drop (DP) by 72.39%, 78.55%, and 64.56% when compared to existing literature correlations. The exceptional accuracy achieved by these correlations contributes significantly to the design, evaluation, and optimization of efficient and compact absorbers, enabling further advancements in this field.