This paper presents the second law analysis of a cross flow forced convection heat exchanger consisting of the pin fins in cylindrical, square and hexagonal shapes placed in a rectangular duct. The pin fins are placed periodically at the top and bottom plates of the duct perpendicular to the flow direction, structured in-line and staggered sheet layouts. Distribution of entropy generation is investigated to demonstrate the rate of irreversibilities in the flow domain. To determine the energy and exergy efficiencies, irreversibility, thermal performance factor and entropy generation number, the heat exchanger is operated at different temperatures and the flow rates by using hot and cold fluids. Optimization of the design parameters and winglet geometry associated with the performance of the heat exchanger are determined by entropy generation minimization. The variation of the entropy generation number due to the heat transfer, fluid friction and optimal cases as a function of Reynolds number for the different pin fins is presented. The Reynolds number is determined according to the experimental plan and performance analysis is accomplished in terms of e-NTU method. It was determined that the increment in fluid velocity enhances the heat transfer rate, which in turn decreases the heat transfer irreversibility.
**TOPICS:**
Thermodynamics, Heat exchangers, Cross-flow, Entropy, Heat transfer, Fins, Flow (Dynamics), Reynolds number, Ducts, Fluids, Viscosity, Temperature, Exergy, Design, Forced convection, Geometry, Shapes, Optimization, Plates (structures)