Waste heat-driven adsorption cooling systems for vehicle air conditioning applications

Waste heat-driven adsorption cooling systems (ACS) are potential replacements for vapor compression refrigeration cycles in vehicle air conditioning (A/C) applications. Working pairs in an ACS are a combination of an adsorbent material (e.g., zeolite and silica gel), and an adsorbate (e.g., water and methanol). Most of these materials are non-toxic, non-corrosive, non-ozone depleting, and inexpensive. Besides, an ACS operates quietly and valves are its only moving parts. However, the bulkiness and heavy weight of ACS are major challenges facing commercialization of these environmentally friendly systems.The focus of this research is to develop a proof-of-concept ACS with high specific cooling power for vehicle A/C applications. As such, this Ph.D. dissertation is divided into three main parts: (i) adsorbent material characterization, (ii) adsorber bed design, and (iii) ACS design. In-depth analytical and thermodynamic cycle models are developed to understand the phenomena in adsorption process, adsorber bed and ACS. Also, a modular two-adsorber bed ACS equipped with thermocouples, pressure transducers and flow meters is designed and built for the first time at the Laboratory for Alternative Energy Conversion (LAEC) to test different adsorbent materials, adsorber beds, condensers, and evaporators under different operating conditions. A low-operating pressure evaporator with capillary-assisted tubes is designed and installed on the testbed to improve the performance of ACS. In addition, a novel expansion valve and control valves are proposed to simplify the control system and reduce the complexity of ACS for vehicle A/C applications. Using this ACS testbed with enhanced performance, a specific cooling power of 150 W/kg of dry adsorbent is achieved.