Development of a compact heat exchanger consisting of tubes and interconnecting struts forming parallel plate arrays: Part I flow visualisation

Abstract

A flow visualisation study has been performed to assess the heat transfer potential of an alternative type of compact heat exchanger. The heat exchanger consists of a conventional tube bundle having flat tubes as used in typical radiator cores. However instead of fins, there are interconnecting rows of heat conducting struts which collectively form a parallel plate array. The purpose of the struts is twofold. They provide a much larger number of leading edges, and since they are arranged in a parallel plate array, they may facilitate the generation of stream wise vortices at certain Reynolds Numbers. The visualisation is performed on Perspex models in order to examine the nature and characteristics of the fluid flow, and identify features which are considered desirable for improved heat transfer. Three strut spacings are examined, at three Reynolds Numbers. It was established that stream wise vortices do occur, particularly at higher Reynolds Numbers and at the widest strut spacings. In Part II of this study, the heat transfer performance of actual coils based on the same configurations of the Perspex models is assessed.