The Optimum Diameter of Silica- Gel Particles in Adsorption Chillers

Adsorption chillers are considered for the industrial and air conditioning applications due to their advantages over the conventional refrigeration systems. The performance of an adsorption chiller is mainly influenced by the adsorbent bed, therefore, this paper investigates a tube heat exchanger with plate fins as the adsorbent bed and silica gel(SWS-1L)-water as working pairs. In order to model the adsorbent bed, the continuity, momentum and energy equations are solved in a body fitted coordinate system and both the inter particle and intra particle mass transfer resistances are considered. The control volume method is used to solve the time dependent equations in four basic domains of thermal fluid, metal tube, fins and adsorbent bed, simultaneously. Flow patterns and pressure distributions though out the bed are examined in detail for all cycle. The results indicate that the particles diameter has a negligible effect on the coefficient of performance, while the specific cooling power and the cycle time have an optimum value for particles diameter of 0.37mm.