Experimental investigations on shell and helical coil solution heat exchanger in NH3-H2O vapour absorption refrigeration system (VAR)

This paper presents the performance investigation of a shell and helical coil type of Solution Heat Exchanger (SHX) in an ammonia-water vapour absorption system. In an absorption system, SHX is one of the major heat recovery components. The main objective of any heat exchanger design is to achieve minimum heat transfer area required for a given heat duty, as it governs the overall fixed cost content of such a system. The required surface area is decided by the overall heat transfer coefficient. Hence, the heat transfer coefficient (HTC) correlation plays a major role in optimizing the heat exchanger. In this paper, shell and helical coil type of SHX is investigated with more emphasis on the dimensionless correlation of shell side co-efficient, which decides the overall HTC and the size of heat exchanger. From the experimental study, shell side heat transfer coefficient of 510-650 W/m(2) K is obtained with the heat exchanger effectiveness of 0.84-0.9 for the tested conditions. A proposed Nusselt number correlation is compared with the experimental results.