Dimensioning, thermal analysis and experimental heat loss coefficients of an adsorptive solar icemaker

The dimensioning, a thermal parameters analysis and the experimental heat loss coefficients of an adsorptive solar refrigerator prototype used for ice production are presented. The solar icemaker operates in an intermittent cycle, i.e. without recovering heat. It uses the activated carbon–methanol pair whose basic components are an adsorber coupled to a static solar collector, a condenser and an evaporator. Some innovations were considered, especially those brought about by French researchers, in which the adsorber was always box-shaped with extended surfaces, and air condensers were used. For the present system, the adsorber is bi-facially irradiated and covered with transparent insulation material (TIM), the geometric configuration of the main components is multi-tubular, and a water condenser is used. TIM polycarbonate covers are used on the top and bottom of the adsorber. The components of the prototype were dimensioned after the results from numerical simulations using meteorological data valid for the hottest six months in João Pessoa (7°8′S, 34°50′WG), whose climate is typically hot and humid. The machine was designed to produce up to 10 kg of ice/day per square meter of solar collection surface. Analyses of the thermal parameters influence on the ice production as well as parameters for dimensioning each component of the machine are presented. The overall heat loss coefficient by the top and the bottom of the adsorber–solar collector component are experimentally evaluated. The tests were performed using an incandescent lamp panel disposed on a 1 m2 surface, totalizing a thermal power of 3600 W. The results show a good efficiency of the TIM covers, achieving overall heat loss coefficient values between 0.54 and 1.90 W m−2 K−1.