Development of a New Multi-Chamber Double-layer Adsorber in Energy Efficient Solar Adsorption Cooling Systems

In recent years, global warming and energy shortage have become more and more serious due to the rapid economic development all over the world. The energy consumed on cooling system accounts for 30-40% of total energy consumption in buildings. The vapor compression (VC) system is the most common used technology for cooling generation but it consumes a large amount of electricity. The refrigerants utilized in the VC system cause strong ozone depletion and global warming. Studies of adsorption cooling systems using solid adsorbents have been ongoing since 1970s, but have not received enough attention compared to the systems using liquid absorbents. Adsorption cooling systems require a heat source and little other electricity supply. Integrating adsorption thermal systems with waste heat or solar energy can substantially reduce the dependence on fossil fuels. In this study, a new multi-chamber double-layer adsorber is designed and manufactured in order to achieve a higher cooling performance of the adsorption cooling system. The optimized performance can be achieved when seven cylindrical shape chambers are integrated into one hexagonal shape adsorber. The amount of adsorbent filled in the new adsorber is calculated, showing a 40% improvement. The total contact surface area between the adsorbent (silica gel) and the adsorbate (water vapor) is also recorded and it shows 100% improvement over the original adsorber. In addition, a prototype of the adsorption cooling system has been built at The Hong Kong University of Science and Technology. Because of manufacturing limitation, only five chambers with fin tubes were installed into the adsorber in the experiment. The coefficient of performance (COP) and the specific cooling power (SCP) are addressed. Under the experimental condition of about 35°C adsorption, 75°C desorption, 30°C condenser and 15°C evaporator temperatures, the COP of the adsorption cooling system is recorded at about 0.26 while the SCP is about 3.4W/kg. Most importantly, it is predictive that the COP and SCP will have a significant improvement after utilizing the new adsorber which installs all 7 chambers in the adsorption cooling system. In conclusion, the results demonstrate that the newly developed adsorber can be a suitable candidate to be used in the adsorption cooling systems.