Direct Effects of Solar Irradiance on a Concentrated Solar Powered Water-Ammonia Absorption Refrigerator

A comprehensive model with respect to the "variable with time" nature of sun thermal energy is developed to assess the direct effects of solar irradiance on the operation and process parameters of a concentrated solar powered single effect ammonia-water absorption refrigerator. This model is composed of coupling three models for the solar collector, heat storage, and absorption refrigerator. The effects of collector area, solar irradiance, and flow rate of hot oil/salt melt variations during the day are calculated through this model. This model is based on the Bird's clear sky irradiation model, validated against the solar irradiance experimental data. The refrigerator model is based on two-phase, two components mass and energy balances for the elements of the refrigeration cycle. A small scale solar concentrated collector is introduced, where salt melts in the temperature range of 215 degrees C to 334.5 degrees C (suitable temperature range in the generator of water-ammonia refrigerators) can be utilised, and an overall collector efficiency of 57.8% is determined. To assure the steady operation of the refrigerator during the day and night with a thermal storage capacity for 12 hours and considering the heat losses thereof, a total capacity of 280 kg to 380 kg thermal storage medium and a collector surface area of 6.3 to 18 m(2) is required. By changing the mass flow rate of salt melt in the collector from 0.005 kg/s to 0.025 kg/s the drastic effects of solar energy change on the parameters of the refrigeratore can be prevented.