Effects of temperature and humidity ratio on the performance of desiccant dehumidification system under low-temperature regeneration

Abstract

The desiccant dehumidification system can separate the latent heat and sensible heat in the air-conditioning system and achieve energy savings by removing latent heat. Industrial waste heat and renewable energy could be utilized in desiccant dehumidification systems, where the desorption process can be performed below 70 °C. The vapor pressure and temperature of the regenerating air dictate the desorption process corresponding to the isotherm properties. This study has focused on the effects of various temperatures and humidity ratios of regeneration air on the performance of a desiccant dehumidifier using a polymer as an adsorbent. Experiments were performed using the regeneration air with the humidity ratios of 0.005 kg kg−1, 0.010 kg kg−1, 0.015 kg kg−1, and 0.020 kg kg−1, while the air temperatures were varied from 40 °C to 70 °C. The evaluation of this study employs the adsorption/desorption amount, average moisture removal capacity, and latent energy ratio (LER) of the regeneration process as key performance indexes. At the regeneration temperature of 68 °C, the peak desorption amount at the humidity ratio of 0.005 kg kg−1 and 0.010 kg kg−1 both reached 0.011 kg kg−1. The results indicated that the higher desorption temperature led to a higher desorption amount. Besides, with the increased desorption temperature, the average moisture removal capacity increases. In contrast, the high humidity ratio of regeneration air resulted in a weak dehumidification ability. Lower regeneration temperature was difficult to apply to regenerate the polymer-based desiccant under a high-humidity-ratio atmosphere. To attain a high LER, a lower humidity ratio of dry air and regeneration temperature was preferred. The regeneration air with a humidity ratio of 0.020 kg kg−1 is not suitable to apply in the dehumidification system in the temperature range of 40–70 °C.