Energetic Performance Optimization of a H_2O-LiBr Absorption Chiller Powered by Evacuated Tube Solar Collector

摘要

Renewable energy sources are expected to be viable alternative solutions to cover the ever-increasing cooling demand, thereby addressing the issue of high-energy consumption by the conventional cooling systems and negative environmental impacts due to the use of chlorinated fluorocarbon compounds (CFCs). Solar energy in particular is one of the promising renewable energy sources due to its abundance in many parts of the world and greenness. The role of solar thermal collectors is to convert the solar energy into heat, which is then used to run a thermally driven cooling system, generating cooling effect in terms of chilled water or conditioned air for buildings environment. Closed and open sorption technologies (absorption, adsorption, and desiccant) appear to be more attractive options to replace the conventional vapor compression cooling systems. Absorption technology is leading in terms of worldwide installation for comfort. However, solar-driven absorption chillers are still not widely commercially available, mainly because of system complexity and relatively high initial investment of the solar field, with about 35% of the total cost. Hence, there is a need for proper sizing of the collector to be integrated with cooling systems. Sizing the solar collector field must not be oversized nor undersized for a given chiller capacity. Oversized collector increases the overall cost of the cooling system as well as potential risk of chiller failure, while undersized collector may lead to low cooling output of the system. Deployment of solar thermal collectors as the primary energy input necessitates proper configuration strategies and optimization. System optimization is the usual approach used for sizing the collector field of solar-powered cooling systems.