Prediction of the frost growth and performance change of air source heat pump system under various frosting conditions

摘要

A numerical model of air source heat pump (ASHP) system under frosting conditions is developed to predict the frost growth rate and performance change of the heat pump system under various frosting conditions. The modified epsilon-NTU model is introduced to compute the heat transfer rate of the evaporator with latent heat generation from the water vapor sublimation. Local frost growth is considered to obtain the non-uniform airflow distribution, air pressure drop, and heat transfer rate. The effect of the frost deposition on the ASHP system is investigated from the suggested model under various frosting conditions. It is shown that the performance drop mostly occurs in the latter part of the frosting process, and the mass of the deposited frost is not directly related to the performance drop. The experimental set up is set to verify the proposed simulation model. The simulation results are in good agreement with the experimental data.