Entropy generation analysis of parallel and counter-flow three-fluid heat exchangers with three thermal communications

Abstract

On the basis of the first and second laws of thermodynamics, the general expression of the number of entropy generation units of three-fluid heat exchangers with three thermal communications was derived. The effect of several non-dimensional design parameters on the number of entropy generation units of three-fluid heat exchangers was thoroughly discussed. Furthermore, the detailed comparisons of results have been given for the arrangement of the parallel flow and the counter flow. It is shown that the variation tendencies of the number of entropy generation units with the ratio of the thermal resistances, ratio of the thermal capacities, and number of heat transfer units for the parallel-flow arrangement are different from those of the counter-flow arrangement. There exists an extremum of the number of entropy generation units for the counter-flow arrangement. In addition, the entropy generation for the counter flow is mostly smaller than that of the parallel flow under the same conditions.