Browsing by Author "Samuel, Teka"

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    Performance Simulation of Solar Adsorption Cooler with Activated Carbon-R134a pairs (ACF-A20, Granular AC and Maxsorb III)
    (Addis Ababa University, 2020-06) Samuel, Teka; Solomon, Tesfamariam (PhD)
    Solar thermal energy can be used to drive sorption coolers. Some of the sorption cooling systems are absorption, adsorption and desiccant systems. This research paper focuses on the performance analysis of adsorption refrigeration system that utilizes activated carbon-R134a pairs. To this end, three variants of activated carbon were assessed for their performance. These types of activated carbon are: ACA-F20, Granular activated carbon and Maxsorb III. These adsorbent materials have varying pore diameter, surface property and adsorption capacities. The solar adsorption system is highly dependent on pressure, temperature and concentration of the adsorbate on the surface of the adsorbent material. Based on the pore diameter of activated carbon Dubinin-Astakhov equation was selected to characterize the adsorption pairs and simulate using MATLAB. For the Dubinin-Astakhov equation, values of characteristic energy, maximum adsorption capacity and exponential constant were adopted from the works of other researchers: Loh and Askalany. The coefficient of performance values of ACA-F20-R134a, Granular-R134a and Maxsorb IIIR134a were found to be 0.27, 0.2908 and 0.311 respectively at bed temperature of 280K. The specific cooling power values for these pairs were 39.29, 49.03 and 62.09 W/kg respectively. Some researchers proposed complex system and found performance values with coefficient of performance values ranging between 0.38-0.7. In this specific research lower values were attained using solar energy unlike the other research works that focused on performance analysis of activated carbon and R134a using waste heat and two stage processes that tend to give higher the cooling effect obtainable by refrigerant R134a. As a result the coefficient of performance values were higher than the one obtained in this research.