Various technical options for developing a solar operatedrefrigerator have been discussed. Their suitability for being usedas a vaccine store for the conditions specified by the World Health(EPI)Organization Expanded Programme on Immunization4have been evaluated.A model to predict the performance of a photovoltaic refrigeratorhave been developed and used to identify factors which influence itsperformance. It was concluded that it can be more competitive inareas where insolation is high and sunshine hours are long. It hasbeen proposed that ice-lined refrigerators, which would run duringthe day, may be more economical and eliminate the need for a batterystorage.The option of operating an 'Electrolux' absorption refrigerator withevacuated tube heat pipe collectors has been assessed. It wasconcluded that the operation was not possible without a majorre-design of the commercially available models. However, it wasproposed that coordination of the EPI with other developmentprogrammes may be useful. It is proposed to build, with thiscoordinated effort, biogas plants. Biogas can then fuel the modifiedburner of the kerosene fueled absorption refrigerators. This maywell prove to be a cheaper option.Characterization of various adsorption pairs has been done using theexperimental rig developed for the purpose. The influence of variousproperties of adsorption pairs on the performance of an adsorption refrigeration cycle has been studied. It was observed that thegeneration temperature in an adsorption refrigeration cycle (or abivariant absorption system), for a specified operating regime, wasonly a function of the refrigerant.A relationship between the refrigerant properties and the generatingtemperature for specified operating conditions was developed. Usingthis relationship it was established that ammonia and methanolcannot be generated at temperatures below 1200C for WHO/EPIspecified operating conditions, if the condenser was air-cooled.A novel idea of direct absorption of solar radiation into theactivated carbon bed is put forward to combat the temperaturedifferential of 214°C, in a conventional design of SGA, between thecarbon and the metal container. The idea was practically implementedby replacing the top of the metal box by transparent glass sheet.The seal between the metal container and glass imposed practicaldifficulties in that design but the tests proved that the idea hadpotential. A new tubular design of the SGA is proposed finally whichis hoped to bring improvement to the performance of activated carbonadsorption refrigerators.
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