Frost Growth Investigation and Temperature Glide Refrigerants in a Fin-and-Tube Heat Exchanger

摘要

Bio methane is produced by removing undesirable components such as water vapor, carbon dioxide and other pollutants in a biogas upgrading process. Frosting the water vapor contained in the biogas is one of the dehydration processes used in a biogas upgrading process. In order to simulate a frost layer on a cold plate, many models have been developed. These models are valid for a limited temperature range. In this study, heat and mass transfer equations were used in a numerical approach to model the frost growth and its densification on the external side of a fin-and-tube heat exchanger. The model used in this study is valid for low temperatures from 0 to -65°C and lower. The evaporation process of temperature glide refrigerants is also modelled. Results show that a decreased heat transfer rate occurred during frost mass growth on fins and rows. During its growth, frost layer thermal conductivity is relatively low leading to a decrease of the cooling load of the heat exchanger. On the other hand, frost layer thickness increases the external surface blockage, leading to higher pressure drop on the external side. This model has been validated by comparing numerical and experimental results.