Characteristic Research And Optimization Of All-weather Solar Jet-variable Compression Cascade Refrigerating System

Development of clean solar energy is one fundamental way to solve energy shortage and environmental problem. In this paper, it proposes an all-weather solar jet- variable compression cascade refrigerating system and the computing model of its main component performance, as well as the refrigeration collector bench, injector performance bench, refrigeration system bench. Through theoretical calculation and experimental study, here are the conclusions.The first, it proposed an all-weather solar jet-variable compression cascade refrigerating method. this system saved about 51% solar energy compared with booster refrigerating system; in the same operating condition, COPm bigger about 45% to 60% than the compression refrigerating system; it can reach a stablecondensing pressure pressure and increase about 28.6% than jet refrigerating system; COPt increases about 105%.The second, it established a theoretical and experimental model of solar jet - variable compression cascade refrigeration system. The results show that: when solar irradiance increases, pressure rises but less than the design pressure, COPm and COPt of cascade refrigerating system both increases; when pressure higher than the design value, COPt becomes small along with the pressure rise, while COPm remains basically unchanged. In the design condensing pressure range, COPm and COPt do not change along with it; beyond the pressure range, COPm and COPt rises. Along with the compressor speed increases, the COPt becomes greater, COPm decreases. Among all devices of this system, collector losses exergy greatest, followed by the condenser and the injector.The third, it established dimensional CFD model of the ejector actual gas. Ejector jet coefficient decreases while compression ratio increases. Based on this, it proposed the jet- compression cascade refrigeration system with a higher COPt. Mach cloud calculated by the model can better study the phenomenon of shock wave changes and return.The forth, it establishes refrigeration collector performance model. When calculating collector heat loss coefficient, the higher of the collector temperature, the more temperature effects should take into account. From the simulation results of thermal performance, heat pipe-vacuum tube collector collector is better. Collector temperature selection should also take jet-compression cacade refrigeration system efficiency and collector efficiency into account.The last, it established dynamic distributed parameter model of heat storage in intermittent operation mode. For the solar jet-variable compression refrigeration system, heat storage guarantees the system's stability. Collector area and volume of heat storage should be designed to meet the need of refrigeration load in typical summer day. Heat storage size should be appropriate, in this paper, concerning about Taiyuan weather conditions, the 1.2m3 would be appropriate.