Development of model based on condensation area ratio and effect on heat transfer capacity of indirect evaporative cooling

摘要

Under the high temperature and humidity environment in summer, the dew point temperature of fresh air is fairly high. When indirect evaporative cooler is applied to cool fresh air in air conditioning system, condensation easily occurs on the wall of primary air channels. In this paper, it is developed a two-dimensional mathematical model for heat and mass transfer of a plate cross-flow indirect evaporative cooler based on condensation area ratio. The model is solved by the finite difference method and MATLAB program. A method for judging condensation state and solving condensation area ratio is proposed, including three states of non-condensation, total condensation and partial condensation. The computational result is in good agreement with the experimental result, and the maximum error is 8.6%. The influence of condensation area ratio on wet-bulb efficiency, dehumidification rate, latent heat transfer and sensible heat transfer of indirect evaporative cooling is investigated. The result shows that condensation area ratio is positively correlated with latent heat transfer, total heat transfer and dehumidification rate, and negatively correlated with sensible heat transfer and wet-bulb efficiency.