Passive hygrometric control of confined environments by means of membrane contactors and hygroscopic solutions

ABSTRACT The present paper investigates the possibility of using hydrophobic membrane vapour exchangers operating with hygroscopic solutions as passive hygrometric stabilisers to control fluctuations in relative humidity in confined environments. We have analysed the behaviour of a room, subject to air leakage and equipped with a temperature control system, inside which an autonomous hygrometric control unit is installed. This device consists of a vapour exchanger that operates between the ambient air recirculated by means of a fan and a hygroscopic solution of LiCl pumped from a storage vessel. The behaviour of the system has been studied by means of a SIMULINK calculation program, developed within the framework of MATLAB. The performance of the system has been evaluated on varying some significant parameters, such as the exchanger surface area and the hygroscopic capacity of the storage vessel. The results, which are expressed in terms of percentile frequency distribution, show that this device is able to significantly restrict short-term fluctuations in relative humidity inside the environment.