NUMERICAL INVESTIGATION OF AN ADSORPTION COOLING SYSTEM POWERED BY RENEWABLE ENERGY FOR USE IN A CAVERN ENVIRONMENT
To support the social and economic development of Hong Kong, there is a pressing need to optimize the supply of land for various usage. Rock cavern development is a sustainable approach to achieve this goal. However, there is an unknown as to whether an adsorption cooling system (ACS) can be used as a cooling scheme in caverns to provide an acceptable thermal comfort. Therefore, this project aims to study the feasibility of using an ACS powered by different heat sources for enhancing overall energy saving in caverns. Modeling is established to
investigate the cooling performance of an ACS driven by both solar energy and waste heat from the sewage treatment process. A novel composite material, multi-walled carbon nanotube embedded zeolite 13X/CaCl2, and water has been utilized as the adsorbent-adsorbate working pair. Additionally, the effluent from the sewage treatment is adopted as the cooling agent for the ACS to further save energy. Different operating conditions, such as adsorption/desorption phase time, waste heat utilization efficiency and solar energy utilization duration, have been studied comprehensively for system optimization. Specific cooling performance (SCP) is the figure of merit
to be investigated numerically. Energy efficiency ratio (EER) has also been determined to obtain the minimum waste heat utilization efficiency. The simulation results show the proposed ACS can achieve an average SCP of 917 W/kg in a one-day operation with an average EER of about 3 at a waste heat utilization efficiency of 50%, demonstrating the feasibility of using the proposed ACS in a cavern environment.