Effect of non-uniform temperature & humidity distribution in the frontal airflow on evaporator frosting performance of a frost-free refrigerator

The frost-free refrigerator typically has three compartments, i.e. refrigerating, variable-temperature and freezing ones. The temperature and humidity (T&H) inside each compartment vary dramatically, leading to non-uniform T&H distribution in the overall return air. Therefore, frost maldistribution occurs on the evaporator and further induces airflow redistribution. In this article, the quasi-static 3-2-1-1 frosting model is built considering 3D evaporator, 2D T&H of frontal airflow, 1D frost growth and 1D non-uniform fin spacing. The model is verified by the experiment data in the open literature. Results show that frost mass is similar with non-uniform and uniform T&H distribution in frontal airflow, but frost distribution is much different. The evaporator capacity for non-uniform airflow is lower at the early stage of frosting process than that for uniform airflow, but higher later due to the airflow transverse redistribution when the airflow transfers transversally from higher to lower T&H areas owing to frost maldistribution. The transverse redistribution results in the air velocity increment and heat transfer compensation effect. Moreover, the fan stall for non-uniform airflow arises later and results in the larger airflow rate and evaporator capacity at later frosting process. (C) 2020 Elsevier Ltd and IIR. All rights reserved.