Desiccant-coated water-sorbing heat exchanger: Weakly-coupled heat and mass transfer

Desiccant-coated, water-sorbing heat exchanger has been proposed and investigated which shows a great advantage to independently treat the sensible and latent heat load but without sacrificing compactness and comfort. Here, a theoretical and experimental study was made to investigate and predict its dynamic behaviors of heat and mass transfer in response to the step change of the operational mode switch which is essential to continuous operation but harmful to its sensible load capacity. The results show that it has a special feature of weakly-coupled heat and mass transfer, which opens up the possibility of adopting temperature and humidity loosely-coupled control strategy to independently control the temperature and humidity on a single exchanger at the same time. Both the outlet air temperature and humidity ratio of the evaporator in response to the step change of the operational mode switch can be described by two individual exponential functions of time, which indicates that the linear driving force model is possibly valid to describe the water uptake kinetics of the water-sorbing heat exchanger even if the real working conditions are non-isothermal and non-steady. (C) 2017 Elsevier Ltd. All rights reserved.