Numerical studies on thermal hydraulic performance of zigzag-type printed circuit heat exchanger with inserted straight channels

Abstract

The printed circuit heat exchanger (PCHE) can include one of many channel types, such as zigzag and wavy channels. Among these channels, the zigzag channel is the most frequently used regarding the conventional-type PCHE due to its high durability and manufacturability; however, the zigzag channel has a high pressure loss due to the flow separation and the reverse flow at the bending point. To improve the performance of the zigzag-type PCHE, a new type of PCHE with inserted straight channels is suggested. A three-dimensional numerical analysis using CFD ANSYS-CFX code is conducted with respect to the thermal-hydraulic performance of a zigzag-type PCHE with inserted straight channels. The effects of the inserted straight channels on the heat transfer and the pressure drop in terms of the mass-flow rate are revealed. The lengths of the inserted straight channels vary between 0.5 and 2 mm, and the mass-flow rate is applied from 1.41 x 10(-4) to 2.48 x 10(-4) kg/s. The pressure drops of the 0.5 mm and 1 mm straight channels are less than that of the zigzag channel, and are similar to that of the wavy channel. In terms of the heat transfer characteristics, the results show that the heat transfer characteristics of the 0.5 mm and 1 mm straight channels are quite similar to those of the zigzag channel, but are better than those of the wavy channel. In the case of the 1 mm straight channel, the value of the volume-goodness factor is improved by about 26-28% compared to that of the original zigzag channel. (C) 2017 Elsevier Ltd. All rights reserved.