Frosting in a heat pump evaporator part B: Numerical analysis

Abstract

This paper is presenting the numerical investigation of the frosting behaviour of a heat pump evaporator in its full complexity, imitating the real-life operation of the experimental setup described in Part A of this publication. The backbone of this work represents the simulation framework for the selected algebraic frost growth model, with the novelty focused on its implementation into a 3D unstructured finite volume general purpose CFD code. The obtained frosting predictions, encompassing the frost growth and the related frost mass increase (responding through the model to the imposed evaporator wall temperature and ambient conditions) interlaced with the resulting change of the flow pattern, are achieving an average agreement within 10% in comparison to the experimental results. The presented modelling framework is applied to the geometrical entirety of the fin and tube evaporator of an air-source heat pump operating under experimentally monitored frosting conditions, and compared with the corresponding frosting results of the evaporator symmetric section, in order to provide the scaling correlation between the frosting characteristics of the full model and the extracted part.