Moisture buffering capacity of novel solar regenerated hygroscopic curtain -

Abstract

This study focuses on the potential use of solar energy to actively regenerate a hygroscopic curtain for control the indoor relative humidity. The proposed curtain is supported by a ceiling rotating shaft to allow the curtain material to continuously exchange heat and moisture with the two environments: facing the curtain and the clearance space behind the curtain. As the curtain slowly rotates, one side facing the internal space will undergo absorption while the other side facing the glass surface will undergo desorption releasing the collected space moisture to the exhausted air stream. In this work a theoretical model is developed from first principles for the proposed system with an integrated indoor space modal to study the rotating hygroscopic curtain feasibility in performing indoor dehumidification. An experimental setup was built inside environmental chambers to validate the theoretical model predictions of room air temperature and moisture removal rate and to test the ability of the rotating curtain to moderate indoor humidity. It was shown that the experimental results for the curtain moisture uptake and the relative humidity inside the chamber compared well with the model simulation results. A case study was evaluated to predict the effectiveness of a hygroscopic curtain made of cotton and placed in a typical office space in the city of Beirut with a floor area of 42 m². It is found that, for the same conditions, hygroscopic curtain maintain an average relative humidity of about 65.7percent when rotating continuously at a speed of 1.5 rpm compared to a value of 71.1percent when the curtain is not rotating at all.