Analytical Modeling And Life Cycle Assessment Of A Solar Powered Vapor Absorption Cooling System

Vapor absorption cooling systems (VACS) offer an environmentally friendly alternative to the standard vapor compression cooling systems (VCCS) for cooling homes, businesses, factories, and other buildings. VACS use low-grade thermal energy to achieve a cooling effect and require minimal electrical input for the liquid solution pump used for circulation within the system. The thermal energy which powers these systems can be provided through several means; one popular form is through the use of solar thermal collectors. This paper provides a process for determining the overall size and configuration of the VACS depending upon the operating conditions of selected components. A mathematical model is provided for the sizing for a 100 refrigeration-ton (RT) VACS. The thermal network which powers the system is composed of counter flow heat exchangers, hot water storage tanks, flat-plate solar thermal collectors, auxiliary electric heaters, and liquid pumps. A life cycle assessment of the sized mathematical model is then presented, with a comparison to the life cycles of heating the system using only electric heaters powered by electricity produced by coal power stations and wood pellet power stations. The global warming potential of each heat source is compared to determine the most environmentally friendly solution and environmental payback period. The proposed solar thermal system for the 100 RT VACS calls for the implementation of 920 flat-plate solar collectors, in arrays consisting of 10 parallel branches of 23 collectors in series, with 4 hot water tanks, and 8 heat exchangers. It is seen that by using the proposed solar thermal system subsidized by wood pellet powered auxiliary heaters, the CO2 emissions of the system are 10 times less than that produced using coal power. The solar and wood pellet co-powered system would replace the usage of almost 1750 metric tons of coal per year. The solar thermal system repays the energy consumed and CO2 produced during the manufacturing stage within 1.9 and 0.2 years respectively