Use of a CFD code in the investigation of cross corrugated heat transfer surfaces

Abstract

The variation of main geometric details of cross corrugated surfaces (i.e. aspect ratio and angle of corrugation) makes it increasingly difficult to have a general design method. In the absence of adequate 'database' covering all possible configurations, it is nearly impossible to predict the highly effective configuration. Thus CFD simulation is effective, as it allows computation for various geometries, and study of the effect of various design configurations on heat transfer and flow characteristics. The present paper discusses the use of a CFD code to select the cross corrugated heat transfer surface (CC surface) with minimum core volume of a recuperator matrix. Due to difficulties Induced by geometry and computational time, simple model is used as a first step. The SS T turbulence model was preferred over other flow models for simulations. This simple model, comprised of three corrugated plates having their crest nearly in contact, with hot and cold fluids flow alternately through passage created between the plates. Some selected cross corrugated heat transfer surfaces are used for the analysis. The results for the simplified model, presented in terms of outlet temperatures, heat transfer coefficients and skin friction coefficients, is encouraging to undertake extensive work in CFD simulation and create more 'database' on various configurations. Design calculations of a recuperator matrix for a 10 kW micro turbine have been carried out for the selected surfaces. The relation between the minimum core volume of the matrix from design calculation and average skin friction coefficient from CFD analysis is established to use CFD analysis for selection of heat transfer surfaces with minimum recuperator matrix core volume. The analysis is carried out with air and nitrogen as heat transfer fluids.