| In the design of a heat exchanger, it is essential to consider the thermodynamic irreversibility or entropy generation rate that takes place inside it. In this study, the entropy generation rate due to heat transfer across the fluid-to-fluid temperature difference, and those due to frictional pressure drop are considered. In this analysis a method for optimizing heat exchangers based on the entropy generation minimization is presented.; The specific analysis for the case of a two-phase flow tube-in-tube heat exchanger, used as a condenser, with refrigerant flowing in the inner tube and water flowing counter-currently in the annulus is presented.; The entropy generation minimization was performed numerically. In the optimization process a non-linear constraint optimization technique was required. The Newton-Raphson search method was used as the optimizing technique and implemented into a numeric tool.; From the optimization procedure, the optimum geometry that leads to the minimum entropy generation rate is found. Namely, this is the optimum combination of inner diameter, outer diameter, and condensing length for all possible sets of combinations.; The methods presented in this analysis will assist the heat transfer equipment designer in obtaining the optimal thermodynamic design that leads to the minimum entropy generation rate. |
