Performance evaluation of silica-gel based desiccant dehumidification unit for air-conditioning applications

Abstract

Low cost and environment friendly air conditioning system are required for many applications like human thermal comfort and industrial process. Conventional vapor-based air condition (VCAC) are not feasible solution due to high energy consumption and harmful effects on environment e.g. ozone layer depletion (OLD), global warming potential (GWP). Water based cooing system (direct and indirect evaporative cooling) can achieve cooling load in dry conditions but in humid conditions not found efficient. In this regard, Desiccant air conditioning (DAC) is a promising technology in order to achieve the required load for air conditioning. In this study, a lab scale silica gel based desiccant unit is developed and its heat and mass transfer characteristics are evaluated in the form of Nusselt number (Nu) and the Sherwood number (Sh). The working principle, important features and experimental procedure of DAC is described. Data is collected at the inlet and outlet of desiccant unit in the form of Temperature (T) and Relative Humidity (RH). Obtained data is used for calculation of the Nu and Sh. Adsorption temperature was considered 30°C and 35°C and time interval is considered at 20:20 $\displaystyle \min$ and 30:30 $\displaystyle \min$ and mass flow rate of air is 0.05 kg/s. The results show that heat and mass are being transferred primarily due to convection.