INVESTIGATION OF A VAPOR BUBBLE PUMP FOR SOLUTION CIRCULATION IN A SOLAR-POWERED ABSORPTION REFRIGERATOR USING METHANOL

摘要

The unreliability of conventional electric power supply in rural settings in Edo State, Nigeria, has necessitated the development of a solar-powered absorption refrigerator for preservation of agricultural produce. However, a standard vapor absorption refrigeration system requires a solution pump to transfer solution, rich in the refrigerant, from the absorber to the generator, via a solution heat exchanger. While solar heat energy derived from untracked flat-plate solar collectors is adequate for generating methanol vapor from a solution of Lithium Bromide/ Zinc Bromide in methanol under vacuum pressures, it is grossly inadequate for powering a mechanical solution pump. This paper investigates the performance of a vapor bubble pump, powered by solar heat from flat plate solar collectors. The pump is used for lifting methanol refrigerant from the generator to a level in a separator from where gravity circulation completes the cycle. An experimental rig was constructed, evacuated and charged with pure methanol and used in testing the performance of the vapor bubble pump. Test results were collated, analyzed and the optimum parameters of the vapor bubble pump determined.