Experimental Solar Thermal Refrigerator Using Methanol as Refrigerant

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Author(s) E. U. Onochie | C. I. Ajuwa | O.A Ighodalo
Pages 374-386
Volume 4
Issue 6
Date June, 2014
Keywords Solar thermal energy; absorption refrigeration; bubble pumps; flat plate solar collectors; Heat Ratio

Abstract

On account of the negative environmental impacts and limited sources of fossil fuels, researchers are increasingly focusing on renewable energy sources, particularly solar energy. This study presents the result of a solar diffusion-absorption refrigerator using methanol as refrigerant and bubble pumps as means of ensuring solution circulation in a system devoid of mechanical pumps. A Solar Thermal Refrigerator using methanol as refrigerant was designed, built and tested using Methanol-Lithium Bromide/Zinc Bromide (CH30H-2LiBr/ZnBr2) solution as the refrigerant-absorbent combination. The system was driven by two modules of south-facing flat plate solar collectors, each having an aperture area of 1 m2 and inclined at 7o to the horizontal at Auchi, Edo State, Nigeria (Lat.7o 4’N; Long. 6o16’ E). On successful assembly, the rig was evacuated and charged with the CH30H-2LiBr-ZnBr2 solution. Test results show that with a daily average regeneration temperature of 55oC, a Heat Ratio, ԐTH (Equivalent Coefficient of Performance (COP) for an absorption refrigeration system) of 0.58 was obtained with an evaporator temperature of 7oC. It can be concluded that it is possible to develop a prototype Solar Thermal Refrigerator suitable for use in farms and rural communities where conventional electric power is scarce or unreliable.

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