Experimental investigation on vapor pressure of desiccant for air conditioning application

Recently, the rapid development of desiccant air conditioning technology, without using refrigerant fluids, energy saving and environmental protection, has expanded natural fluid to a broader niche applications. An experimental study is carried out to calculate the vapor pressure of CaCl2 using regression dependent parameters and evaluate the mass transfer coefficient. The effect of relevant operating parameters, such as air temperature, humidity and air velocity on the mass transfer processes between the air and the desiccant CaCl2 is analyzed. For a detailed study of the dehumidification process and desiccant regeneration, a "DVS", a "Dryer" and "climatic chamber" equipment are used. Several measurements were made in a relatively large range of operating conditions. It was found that the absorption mass rate increased linearly with increasing air humidity. After 6 hour of absorption the mass transfer becomes slow. The mass transfer coefficient is affected by the climatic condition variation. The decrease in mass transfer potential with time is mainly due to vapour pressure rise on the desiccant surface during absorption. The vapor pressure is significantly affected by the air humidity variation. At higher humidity, the concentration decreases while the vapor pressure increases. The mass transfer process duration decreased with increasing the air velocity during the desiccant regeneration. It can be pointed out that the CaCl2 is able to absorb moisture and can be regenerated at low temperature then; solar collector can be used in liquid desiccant cooling system. This study allows selecting the best desiccant for use in LDAC system. (C) 2017 The Authors. Published by Elsevier B.V.