Investigation of entropy generation rate and its minimization in helical grooved tubes

Abstract

Surface enhancement in heat exchangers has been actively researched, but enhancements have been mainly on the tube side, involving optimization of the geometry. The effect of surface enhancement has been studied in great detail experimentally, but numerical studies are scarce and involve performance comparisons based on the friction factor and Nusselt number. However, true performance can be assessed based on entropy generation minimization. We performed a numerical study on tubes with helical groove formation to assess entropy generation minimization. The tube data were initially validated experimentally and tube performance was then examined via thermal enhancement factors and entropy generation minimization. The Reynolds number was taken as 5000 to 10000 in accordance with an experimental study. All the tubes had an enhancement factor greater than unity, meaning that they were thermally efficient. However, with regard to irreversibility, the tube with the minimum pitch-0.051 m-(GT02) produced the lowest value and hence the minimum entropy generation rate, and thus represented the optimal choice for heat exchangers.