Modeling non-uniform frost growth on a fin-and-tube heat exchanger

A semi-empirical model that predicts non-uniform frost growth on heat exchangers is developed and experimentally validated. The model is based on a scaling approach that uses the average frost layer properties to predict growth in a quasi-steady state, heat and mass balance based segment-by-segment coil simulation. The air redistribution algorithm in the model improved frost thickness predictions by 20%–50% and coil capacity predictions by 42% compared to the same model without air redistribution. The model along with an empirical frost delay predicted the frost thickness for different inlet refrigerant temperatures, air relative humidities and air velocities under non-uniform frosting with a root mean square error of 3.7%, 9.8% and 5.2% respectively.

► A semi-empirical model for frost growth in fin-tube heat exchanger is presented.
► Model accounts for non-uniformity on air side and refrigerant side and models the couple effect of such non-uniformities and associated airflow.
► Model is validated for various refrigerant and air inlet conditions.
► Model performed very well for all the cases it was validated.
► Model demonstrated the importance of accounting air redistribution during non-uniform frost growth.