Numerical Improvement Using Flow and Heat Transfer Calculations of the Zigzag Geometry for Carbon Dioxide PCHEs

Abstract

A printed circuit heat exchanger (PCHE) is an efficient and compact heat exchanger that can work under high temperature and high pressure. For Z-shaped channel PCHEs, the corner structure could enhance heat transfer at the expense of increasing the flow resistance. In order to optimize the structural design and control the pressure loss caused by the corner, a three-dimensional numerical simulation using ICEM and Fluent is conducted to study the flow and heat transfer characteristics of carbon dioxide in a PCHE by inserting straight sections (offset distance 0.5–4 mm) or arc segments (radius of curvature 0.5–4 mm) at the zigzag corners of conventional Z-shaped channels. The overall performance of the PCHEs with different structures was compared based on the comprehensive evaluation factor. The results show that the pressure loss of the PCHE can be significantly reduced by inserting straight sections and arc segments at the zigzag corners, with the mass flow rate varying from 100 to 400 kg/(m2 s). The greater the offset distance of the straight sections or curvature radius of the arc segments are, the more significant the effect is, but the heat transfer performance will be weakened at the same time. The comprehensive performance of the PCHE was the best when the curvature radius of the arc segment inserted at the zigzag corner was 4 mm.