Dynamics of a cross-flow heat exchanger with fins

Abstract

Considerable temperature gradients are often found in the stationary case in the single fins of an air-water heat exchanger. A theoretical investigation of the effect of the dynamics of the fins has been performed for the over-all heat exchanger dynamics. A model which includes radial and axial temperature profiles is compared with a simple model where radial gradients are neglected. For most practical cases it is found that the simple model represents the dynamics very well at frequencies below 10–15 rad/min. The model for the fin is solved with high accuracy using a low order orthogonal collocation approach and the complicated 3-dimensional heat exchanger model is thus reduced to a computationally simple system.