First and second law analysis of compact heat exchangers used for intercooling purposes

Intercooling is a process that is employed in turbocharged engines to cool the charge air. This cooling enables to feed more air into the cylinders and decreases the operating temperatures of the engine. Intercoolers -kind of compact heat exchangers- are used to carry out this process. Depending on the required thermal-hydraulic performance, intercoolers can be designed using different fin types. In this study, the fin types that are utilized in the design of intercoolers are theoretically examined using the first and second law of thermodynamics. For this purpose, various intercooler configurations are established with five different fin geometries, namely plain fins, louvered fins, offset strip fins, wavy fins and perforated fins. Then, sizing and rating procedures are applied on these configurations. In sizing procedure, the dimensions of the intercooler configurations are determined. In rating procedure, heat transfer, pressure drop and second law performances of the configurations are computed. The obtained results are tabulated and compared with each other. It is found that offset strip fins provide very good heat transfer performances whereas plain fins enable least pressure drops in the fluid pressures. In second law analysis the following outcome is attained; since the configurations in this study have unbalanced flow, eliminating entropy generation or exergy destruction is not possible even with an infinite surface area and zero pressure drops. Keywords: Turbocharging, intercooling, intercoolers, compact heat exchangers, plate-fin heat exchangers, heat transfer, pressure drop, second law analysis.