Experimental Study on Heat Transfer in Wavy Channels

Abstract

Plate heat exchangers (PHEs) are currently used as heat transfer components in refrigeration systems. The major characteristics of PHEs are their wavy flow channels. Detailed knowledge of the transport phenomena within the channel is thus a necessity. Unfortunately, the available literature primarily emphasizes the overall performance of PHEs. This experimental study is thus intended to investigate the effect of channel geometry and flow conditions on the heat transfer of the exchangers. In this work, two stainless steel cases with surfaces of the same wavy shape were clipped between two metal plates to constitute the required flow channel, through which air was passed. The shape of the corrugated surface could be changed for different cases. The temperature of the wall was kept constant with hot water. Starting from the entrance, the temperature distribution within the channel of two wavelengths was monitored with thermocouples. The geometric parameters investigated in this work include the width (W) and corrugated angle (b) of the flow channel. The flow rate of air was also varied to study the effect of the Reynolds number (Re). Results indicate that the local Nusselt number (Nux) is greater at sections close to the wave crest than at other regions within the channel. The average Nusselt number (Nu) increases with Re and b but does not change apparently with W. Nux increases with Re but decreases with the distances from the entrance of the channel. Furthermore, the heat transfer coefficient (hm) increases with b but decreases with W.