Thermal performance optimization principle on absorption heat exchanger utilizing LiBr/H2O solution as working fluids: Integration, interpretation and improvement

In the district heating system, the absorption heat exchanger (AHE) has been widely utilized in the heating station. To improve thermal performance, a large amount of research has analyzed, designed, and optimized different AHEs from the aspects of processes and internal parameters. However, existing results are not comprehensive, lacking specific optimization principles for some optimizable links and the interpretations of essential reasons. The purpose of this paper is to address the above issues. First, based on the AHE's arrangements, all optimizable links are integrated, existing research conclusions for each optimization link are elaborated, and the limitations are proposed. Secondly, a simplified but effective thermodynamic model of AHE utilizing LiBr/H2O solution is first proposed in this paper. Based on this model, effective optimization principles are proposed for the unresolved connection way design and flow rate distribution issue of the secondary network water, and the essential reasons are interpreted. Finally, the overall optimization principle of AHE is summarized, and it is utilized to optimize an actual two-stage AHE. Under the same cost, the optimized system can further improve the heat exchange efficiency by 8.5 %. The principle proposed in this paper applies to different AHE processes and conditions, which have guiding significance.