Energy Analysis of Liquid Desiccant Based Evaporative Cooling System

This paper presents preliminary findings of the energy analysis of a cooling system with multistage evaporative coolers using liquid desiccant dehumidifier between the stages. The proposed evaporative cooling system utilizes the air humidity for cooling in humid areas and requires no additional water supply. The major energy requirement associated with this cooling system is the energy for regenerating the weak liquid desiccant. In this paper two types of energy namely thermal energy as well as mechanical energy are considered for regeneration. For thermal energy, the heat input for regeneration is supplied from the conventional energy sources such as a simple line heater. Reverse osmosis (RO) process is considered for regeneration by mechanical energy and MFI zeolite membrane is proposed for separation of water from the weak desiccant solution. Energy analysis has been carried out for both methods of regeneration. The results show that the energy consumption is about 25% less for the mechanical regeneration system with 3 % recovery than the thermal energy regeneration system to increase the desiccant solution temperature of 22°C. The COP of the proposed cooling system is defined as the cooling effect by the mass rate of water evaporated in the system divided by the amount of energy supplied to the system, that is, the COP is independent of the energy source.