APPLICATION OF ENTROPY GENERATION MINIMIZATION FOR OPTIMIZING THE GEOMETRY OF A DOUBLE-TUBE HEAT EXCHANGER

The paper presents an analysis of entropy generation for a double-tube heat exchanger with water as heat transferring fluids. Four heat exchanger configurations were considered: with the heating fluid in the inner and outer tubes, and with parallel and counter flows. The aim of the analysis was to determine the tube inner [inner tube] diameter for which entropy generation is minimum. The entropy generation resulting from heat flow and from resistance to flow (pressure losses) of heat transferring fluids were taken into account. The minimum of entropy generation as a function of the inner tube diameter was found for two cases: for the counter and parallel flows when the cold fluid flows through the inner tube and the hot fluid passes through the space between the tubes. For two other cases of the counter and parallel flows when the hot fluid flows through the inner tube and the cold fluid passes through the space between the tubes, entropy generation is approximately linearly decreasing with the increase in the inner tube diameter, and there is no entropy generation extremum (minimum) in the range of dimensions analyzed in the study.