Effect of airflow rate on frost formation and performance of membrane energy exchangers in sub-zero conditions

Frost formation in membrane energy exchangers under cold climates poses significant operational challenges. This study comprehensively investigates the influence of airflow rate on frost formation and the performance of the energy exchanger through experimental and theoretical analyses. It was found that higher airflow rates increase the risk of frost formation while reducing the airflow rate effectively mitigates frost formation. Frost had a greater adverse effect on sensible effectiveness than latent effectiveness, leading to decreased heat transfer performance. The sensible effectiveness decreased by 15.3 % at 400 m3/h after one hour, while the latent effectiveness only decreased by 13.0 %. The risk of frost formation was influenced by outdoor air temperature and extract air relative humidity. The impact of outdoor air relative humidity and extract air temperature was relatively small. The findings provide practical insights for optimizing airflow rates to prevent frost formation and enhance energy exchanger performance, contributing to the development of more efficient heat recovery systems.