Theoretical and experimental research on heat and mass transfer process of positive pressure condensation dehumidification for humid air

Abstract

Air condensation dehumidification is the main dehumidification method, which dehumidifies by cooling the air temperature below its dew point temperature. The process of atmospheric condensation dehumidification requires chillers to obtain lower temperature cooling sources, which leads to reheat loss. In this paper, the positive pressure condensation dehumidification method for humid air is proposed, as the dew point temperature of air is increased with the pressure. By this way, natural cooling sources or evaporative cooling towers can be used instead of refrigeration systems for cooling and dehumidification. The heat and mass transfer model of the positive pressure condensation dehumidification process for humid air is developed, which has three parts: single droplet part, droplet growth part, and single tube condensation part. Positive pressure condensation dehumidification experiments with different pressures are carried out, and experimental results show that the model accuracy is within ± 10 %. Additionally, theoretical results indicate that the heat and mass transfer rate within the pressure range of 160–290 kPa is about 2.5–3.4 times higher than that at atmospheric pressure, and the humidity of the air after dehumidification is 15.6–10.9 g/kg, which is less than half of that at atmospheric pressure.