Researcher Atyab Safaa Saleem's master's thesis, titled Simulation of an Absorption Refrigeration System Powered by a Solar Pond was discussed at the College of Engineering, University of Basra's Department of Mechanical Engineering. It includes: During the hot summer months, demand for air conditioning increases, as it relies primarily on electricity supplied by fossil fuels. Conventional vapor compression systems consume large amounts of electricity and also damage the ozone layer. Therefore, there is a need for alternative systems, such as absorption cooling systems powered by renewable and inexpensive heat sources, such as solar energy.
The thermal performance of a solar pond-heated absorption refrigeration system was studied and simulated under the climatic conditions of Basrah, Iraq. The simulation was conducted over several months of the year, from March to October, taking into account daily climate variables, such as solar radiation and ambient temperature, specific to Basrah. This enabled the evaluation of system performance under realistic climatic conditions. The simulation used MATLAB to solve the heat and mass transfer equations within the three layers of the solar pond (assuming sodium chloride as the salinity gradient medium). It linked them via a heat exchanger to the absorption refrigeration system to determine the temperatures supplied to the absorption cycle. The absorption refrigeration system operates on a lithium bromide-water pair and features an internal heat exchanger between the generator and absorber, with an assumed efficiency of 80%.
The solar pond had an area of 2 and a depth of 1 m, with layer thicknesses of 0.1 m, 0.6 m, and 0.3 m for the upper, non-convective, and lower layers, respectively. The sodium chloride concentration was 10 kg/m³ in the upper layer and 177 kg/m³ in the lower layer, with a salt gradient that increased with depth in the middle layer. The absorption system was designed to operate at condenser and evaporator temperatures of 40°C and 5°C, respectively, with a generator temperature range of 65.5–95°C and an absorber temperature range of 27.2–38°C.
The study demonstrated the feasibility of operating an absorption refrigeration system using the thermal energy stored in the lower layer of the solar pond while maintaining good thermal stability throughout the day, especially in areas with high solar radiation, such as Basrah. Basrah's climate supports the use of a solar-powered absorption refrigeration system, particularly during summer. The study concluded that July offers the best thermal performance for the entire system, with the highest monthly temperature of the lower layer recorded at 125°C at the end of July. The highest thermal efficiency of the solar pond reached 90%, and the maximum heat supplied to the generator was 255 kW, corresponding to a maximum cooling capacity of 140 kW. The highest monthly Coefficient of Performance (COP) for the absorption refrigeration system was 0.56 at the end of July, making it the most important month in terms of peak solar radiation.
