This present work has theoretically investigated coupled heat and mass exchangemechanisms in counterflow rotary dehumidifier with the mixed desiccant of LiCl and additives,used in air conditioning systems. Mathematical model has been derived, based on one-dimensionaltransfer model and Polyni potential theory (theory of water chemical potential)and solved, using digital computer. The profiles of temperature and absolute humidity distributionin the matrix have been obtained. Analysis shows, that the direction of mass transfer isopposite to positive water vapour partial pressure.
Temperature and relative humidity have been measured in a BRE test house to investigate the vapour content in the void beneath the timber floor. The void can be ventilated naturally or by means of a fan supplying or extracting air. The results show that air flow into and out of the void is stack dominated. The fan needs to supply or extract large volumes of air in order to disrupt this. Measurements and modelling have shown that the vapour content in the void is generally dependent on the level in external air, and that the contribution from the ground is usually small by comparison.
The objectives of thisinvestigation were to examine the dynamic water vapour sorption offurnishing materials and to compare the experimental results withpredictions obtained from the Moisture Admittance Model. Dynamic sorption measurementswere carried out for common building materials. The measurements were made by placingspecimens of the materials in a humidity chamber and varying the ambient humidity between46% and 90% RH at constant 22C. The weight of the specimens was monitored in situduring this procedure.
New thermodynamic energy "water potential" based on the chemical potential of a component of mixture gases is defined as the driving force of gaseous phase water flux. Adhesive power, which is a kind of stress call "capillary attraction" and a part of the water potential, is proved as the driving force of liquid phase water flux. Then numerical model of coupled heat and water transfer using the water potential is introduced and influences of stress such as gravity and stationary pressure on water flux are clarified from the viewpoint of thermodynamics.
Login