Simulation of an Air Cooled Single-Effect Solar Absorption Cooling System with Evacuated Tube Collectors

摘要

Consistently increasing CO2 emission and ozone depletion from synthetic refrigerants are serious environmental issues challenging the scientific community. Absorption cooling systems give scope of utilizing low grade energy source for generating cooling effect. Solar energy is one of these low grade energy sources and with considering the fact that cooling demand increases with the intensity of solar radiation, solar refrigeration has been considered as a logical solution.This thesis consists of two different simulation stages, in the first stage, a single effect lithium bromide absorption cooling system with constant cooling capacity is modeled and the effect of ambient and generator temperatures on concentration and strong solution flow rate is investigated. Then the energy required by the generator and the resulting coefficient of performance (COP) are analyzed by varying all parameters: for instance, strong and weak solution concentration, generator temperature, and ambient temperature. This simulation shows that the generator temperature needs to be increased for higher ambient temperatures and there is one optimum generator temperature that gives the highest COP. The overall COP after using the control system was between 0.75 and 0.85.In next stage of the analysis, the sun position and hot water production for cooling season (May through September) in Las Vegas are simulated using TMY3 data and considered using evacuated tube solar collectors. To size the collector area, the hottest day (4th of June at 3 PM) is selected to fulfill the maximum cooling demand and according to amount of solar radiation, ambient temperature, and energy required by generator, the number of collectors is defined. Generally, the solar system is found to be effective and covered 35% of heating demand to run the cooling system continuously through the cooling season.