Numerical Modeling of Fin and Tube Heat Exchanger for Waste Heat Recovery

In the present work, multiphysics numerical modeling is carried out to predict the performance of a liquid-gas fin and tube heat exchanger design. Three-dimensional (3D) steady-state numerical model using commercial software COMSOL based on finite element method (FEM) is developed. The study associates conjugate heat transfer phenomenon with the turbulent flow to describe the variable temperature and velocity profile. The performance of heat exchanger design is investigated in terms of overall heat transfer coefficient, Nusselt number, Colburn j-factor, flow resistance factor, and efficiency index. In addition, the impact of thermal contact resistance at an interface between fin and tube on the performance is examined. It is found that contact resistance of 3.3 x 10-6 (Km2)/W can reduce the overall performance by approx. 6% when compared with the case of no thermal contact resistance between fin and tube. The present numerical model predicts the performance of the heat exchanger design, therefore, can be applied to existing waste heat recovery systems to improve the overall performance with optimized design and process-dependent parameters.