Effect of overall thermal conductance with different mass allocation on a three stage adsorption chiller employing re-heat scheme

Abstract

Silica gel/water based adsorption cycles have a distinct advantage in their ability to be driven by heat of relatively low and near environment temperature so that the waste heat below 100ºC can be recovered, which is highly desirable. One interesting feature of refrigeration cycles is driven by waste heat where it does not use electricity or fossil fuels as driving sources as energy savers. In this dissertation, a numerical investigation of a three-stage adsorption refrigeration chiller using re-heat with different mass allocation has been performed. The influences of the overall thermal conductance of sorption elements, condenser, and evaporator as well as the heat source temperature on the chiller performance have been conducted. The innovative chiller has been powered by waste heat or renewable energy sources of temperature between 45 and 65°C along with a coolant of inlet temperature at 30°C for air-conditioning purpose. Result shows that cycle performance has been strongly influenced by the large thermal conductance values and it gives optimum result for low value of cooling water temperature. With the same operating conditions, such as the heat transfer fluid (HTF) inlet temperatures, HTF flow rates, adsorption/desorption cycle time, and the same chiller physical dimension, it is found that both the Cooling Capacity (CC) and Coefficient of Performance (COP) of the present study are much better than the previous study which is published by Khan et al. [2008], that is, CC has been improved 13.32% and COP has been improved 15.13% while the hot water and cooling water temperature is at 60 and 30℃, respectively.