A Feasiblity Study of the Placement of a Heated Turbulence Grid in Front of an Air-Cooled Fuel Cell Stack in Subzero Conditions

Abstract

Within telecom back-up applications, the air-cooled fuel cell is a promising alternative to diesel generators as a backup powersystem. Additionally, these fuel cell systems are required to operate in a subzero environment with temperaturesas low as -40C. In this study, a numerical analysis of a heated turbulence-inducing grid to preheat the air before the cathode channel, has been conducted. The turbulence model used is the comprehensive Reynolds Stress Model. Four different grid dimensions, namely grid with 1mm in depth and six 1 mm2 holes, grid with 2mm in depth and six 1 mm2 holes, grid with 1mm in depth and twenty-four 0.17 mm2 holes, grid with 2mm in depth and twenty-four 0.17 mm2 holes have been considered. The outside temperature has been varied from -20C and -10C and heated up to 5C before air flow enters the cathode. A three-dimensional, steady state numerical analysis has been conducted on these grid dimensions using the finite volume method. First results indicate very high grid surface temperatures. Additionally, it can be concluded that the grid surfacetemperature decreases as the turbulence grid thickens. Figure 1