Project Name : Hybrid Desiccant Cooling Systems
Project Theme: Community Health & Environment
Aim: Sansodhan Urja With drastically change in climatic conditions in recent years; demand for air conditioning is spreading all over the world. In order to provide best indoor air quality and thermal comfort with minimum consumption of energy, hybrid desiccant cooling systems are an approach to effectively manage humidity under challenging conditions such as buildings with high outdoor air (OA) requirements located in humid regions. The hybrid desiccant cooling system helps in removing moisture and latent heat (and possibly sensible heat) from process air. Thus, the incoming fresh air
becomes totally dry and increases the overall cooling efficiency.
Hybrid desiccant cooling system has two essential components, an absorber and a regenerator. In a basic configuration, strong i.e.…concentrated and cooled liquid desiccant flows into the absorber and down through a packed bed of granular particles (or other enhanced mass transfer surface or packing). Counter flowing return air passes through the bed, transferring both moisture and heat to the liquid desiccant. The water absorbed from the air dilutes the liquid desiccant leaving the bottom of the packed bed, and flows into the regenerator. In the regenerator, the heat source (gas or oil – fired, waste heat, solar) heats the weak liquid desiccant solution, increasing the vapor pressure of the water. When the weak desiccant is sprayed on another packed bed, the absorbed moisture migrates to a counter flowing scavenger air stream to regenerate a concentrated liquid desiccantc solution. Subsequently the return feed from the regenerator passes through a cooling tower to remove the heat input from the regenerator. Finally, the cooled liquid desiccant solution returns to the absorber to complete the cycle.
In the present investigations, an experimental study has been conducted on hybrid desiccant cooling system, where the latent heat and sensible heat of air are removed by mixing it with the – desiccant solution in a counter flow manner. This makes air totally dry and thus saves the energy to cool the air in refrigeration system. The desiccant chosen here is the aqueous solution of calcium chloride. The packed bed inside the absorber as well as regenerator consists of polypropylene, cascade ring for the better mixing of air and desiccant solution. The effect of various parameters such as desiccant inlet temperature, air inlet temperature, mass flow rate of air and desiccant solution has been studied to investigate the performance of the system. Comparing the results with previous studies, a fair agreement has been reported.
Name of the School: Darbari Lal DAV Model School, Pitampura, New
Delhi.
