Performance of total heat recovery device using liquid desiccant in severe cold climates

摘要

Due to the significant parameter difference between indoors and outdoors in severe cold climates, recovering the total heat of the indoor exhaust air is essential. The problem that hinders the normal operation of a total heat recovery device in winter conditions is the risk of icing. Conventional heat recovery devices are limited by the ice line of water and are easy to freeze at 0 degrees C. The advantage of liquid desiccant is that the freezing temperature can be much lower than 0 degrees C. Performance of a total heat recovery device using liquid desiccant (LDHR device) is analyzed in the present study, which could operate normally when the temperature outside is above -15 degrees C. Two improved LDHR devices are proposed by preheating the desiccant or preheating the outdoor air. They could operate normally when temperature outside is -30 degrees C similar to -15 degrees C respectively. Effects of preheating on the performance of the improved LDHR device are investigated. The optimized control method is that the device happens to be non-freezing. Under this control method, the performance of preheating outdoor air is better than preheating the desiccant. When the current device is in summer condition or the outdoor temperature is greater than -15 degrees C, the total heat recovery efficiency (eta(h)) is about 70%. The improved LDHR devices could operate normally when the temperature outside is -20 degrees C, -25 degrees C, -30 degrees C. and the eta(h) is about 62.5%, 58.3% and 54.6%, respectively. (C) 2019 Elsevier B.V. All rights reserved.