Performance Simulation of Solar Adsorption Cooler with Activated Carbon-R134a pairs (ACF-A20, Granular AC and Maxsorb III)
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Date
2020-06
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Addis Ababa University
Abstract
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.
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Keywords
Adsorption refrigeration, Activated Carbon, R134a, Coefficient of Performance, Specific cooling power, Dubnin Asthakov equation