A novel solar integrated distillation and cooling system – Design and analysis

Abstract

To meet the high cooling and fresh water demands in hot and arid regions, a novel integrated solar cooling and solar distillation system is introduced. The system consists of a solar ejector cooling system integrated with single-slope solar still. The proposed novel system is the first study to integrate two solar systems for cooling and water production with outputs significantly higher than any existing system. A steady state thermodynamics model is developed based on the mass, momentum and energy conservations and the performance of the integrated system is investigated. Results showed that the productivity of the solar still is enhanced by increasing the evaporation rate (using heating coil) and by increasing the condensation rate (using cooling coil). Simultaneously, this improved the COP of the ejector system by enhancing its entrainment ratio with slight increase in the required solar collector area. The performance of the system is investigated further for four different scenarios of integration between the solar ejector cooling and solar distillation systems. Results showed that the productivity of the still is five times higher than that of the conventional solar still. The effects of the major operating parameters on the performance of the system with R134a as the working fluid are investigated and analyzed. At a solar radiation of 500 W/m2, generator pressure of 3.3 MPa, generator temperature of 365 K, evaporator temperature of 283 K, a cooling capacity of 10.4 kW and distilled water of 8.10 kg/day are obtained. The annual produced water considering the hourly variation of the radiant flux was 5067 kg/year, which is 5.7 times more than the conventional systems. The estimated cost of one liter distilled water per 1 m2 area of the present solar still is $0.04, which is only 18% of the water cost of other still technologies. Moreover, the performance of additional four working fluids is compared in terms of COP, cooling capacity, required solar collector area and still productivity, based on which, R134a working fluid was recommended for its overall performance.