Continuum Computational Fluid Dynamics model of heat transfer in monolith converter

Atul Pant,¹ Thiyagarajan Paramadayalan<sup>2

1</sup>Global General Motors R&D, India Science Lab, GM Tech Center (India), Bangalore, India; ²GM Powertrain-India, Engine CAE, GM Tech Center (India), Bangalore, India

Abstract: A continuum model representation of transient heat transfer in monoliths with square channels requires solving separate energy balance for gas and solid domains. Comparison of continuum model predictions with results of a full three-dimensional model of distributed square channels shows that besides adequate estimation of effective radial thermal conductivity, heat flux at boundary also needs to be properly assigned. It is shown that solving separate energy balances for solid and fluid domains requires splitting the total boundary heat flux between the two domains. The heat flux can be split based on thermal resistance of the fluid and solid domain in the continuum model. Heat transfer in a monolith with 1024 square channels is simulated using the proposed continuum approach and the direct approach considering each individual channel. The continuum model predicts the radial variation in temperature to within 6°C of that obtained in the actual channel model. Using the model to simulate the heating up of the monolith with hot inlet gas and heat loss at the boundary shows that the heat loss at the monolith boundary does not penetrate to more than three channels near the wall.

Keywords: monolith reactors, heat conduction, heat transfer, mathematical modeling, numerical analysis, porous media