A Feasibility Study of Placing a Heated Turbulence Grid in Front of an Air-Cooled Fuel Cell Stack in Freezing Conditions

This paper aims to better understand the temperature profile of a turbulence inducing grid if pre-heating of the incoming air in the cathode channel is required when the stack is operating under freezing conditions. The goal of this study is to design the grid by changing its thickness and the number of pores. A three-dimensional, steady-state computational fluid dynamic model was developed and validated for a baseline case of a single cathode channel of an air-cooled cell. The computational domain consists of the cathode flow channel, a gas diffusion layer, and the turbulence inducing grid. Four different grid designs were analyzed and compared, and in the best case heating of the turbulence grid was achieved where the temperature of the grid will be 236 °C and the power consumption will be around 30 % of the total power produced by the fuel cell stack. It is concluded that 2 mm thickness is not sufficient, leading to too high temperatures, and a multitude of staggered grids might be required.