DEVELOPMENT OF A SOLAR POWERED REFRIGERATOR

Abstract

The possibilities of using solar energy for producing cooling effect have been demonstrated by several investigators, but the engineering system design and economic feasibility have not been touched upon-. In the present investigation, the objective has been to develop an engineered solar powered refrigerator catering to the require-ments of a health centre or a typical house-hold in remote rural regions of India, where electricity is not available. Further, an investigation has been carried out to check its performance in summer and winter operation alongwith the economic evaluation. The system consists of the following units: 1. Vapour Absorption Module An intermittent aqua-ammonia absorption refrigeration system consisting of a generator cum absorber, rectifier, condenser, receiver, evaporator, brine tank and refrigerator cabinet forms the vapour absorption module. It can be operated by input of solar energy as well as by energy input from biogas fired heaters and agrowaste heaters via a heat exchanger. Instrumentation has been provided for indica-ting temperature, pressure, and for finding the ammonia distilled and the solar insolation. Valves are provided for isolating the various sections of the system. 2. Main Solar Collectors: The solar energy is collected by flat plate collector which consists of a tube bank containing aqua-ammonia solution. It also acts as a generator cum absorber for the vapour absorption system. The solar energy is assisted by biogas fired heaters so that economic operation of the system takes place. 3. Biogas Fired Assisting Heater: In remote rural regions biogas is available and as such its energy has been coupled to the solar powered refrigerator to have economic operation of the system. It not only increases the reliability of the system, but also makes the solar powered ill refrigerator economically viable for the particular applications where cooling by ice boxes is being done presently. 4. Solar Chimney: To have more or less dry ammonia in the condenser for condensation, a rectifier has been installed between the generator and the condenser. To provide a continuous stream of ambient air over the rectifier, a solar chimney has been used. This is an innovative device which cools the mixture of ammonia vapour and water vapour coming from the generator to a level, where water vapour is condensed and drips back to the generator.