Solar-Thermal Tri-Generation System

The solar-thermal tri-generation system is designed to address the high-energy costs associated with power production, refrigeration, and heating in lesser developed areas or emergency situations. Our system at ESC is currently in the testing process for power generation, refrigeration, and water heating; it consists of a concentrating solar concentrator and a thermal receiver. The solar concentrator is of the parabolic dish type, which is covered with a reflective aluminized mylar. This focuses the sun’s rays onto the receiver mounted at the focal point of the concentrator. The extreme temperatures created at the focal region, in excess of 650C, is then transferred by the receiver to heat a circulating fluid, which is then transported elsewhere for various thermal uses. For power production, the working fluid is water, which is flashed to steam. This high-temperature, high-pressure steam is then expanded through a small high-speed turbine coupled with a generator for electric power production. The exhaust steam is then condensed before reentering the system so as to minimize working fluid losses and increase system efficiency by preheating the working fluid. For refrigeration and water heating, an ethylene-glycol mixture is used. The ethylene-glycol mixture is used as a thermal transport medium to transfer the heat from the receiver to a thermal reservoir. For refrigeration, the thermal reservoir is used in conjunction with an anhydrous-ammonia refrigeration cycle. This cycle is similar to the conventional refrigeration cycle, however, instead of the refrigerant being compressed by the work of a shaft from an electric compressor, it is pressure driven by the addition of heat, thus making off-grid refrigeration plausible. For water heating, a heat exchanger is used in the thermal storage reservoir. Instead of water being heated by an electric heating element, the heat will be transferred from the thermal reservoir to the water. Ideally, all three components for the system will be able to operate simultaneously for tri-generation in areas where off-grid availability is essential.