| Along with the further development of industrialization in global, accelerate development and use of oil, coal and other non-renewable energy. On the one hand a lot of resources consumed, on the other hand, the use of fossil fuels pollutes the environment significantly, resulting in global warming and other global environmental problems. These pose a serious threat for survival and development of human and other organism. Therefore, in order to solve the energy problems and achieve sustainable development can only rely on the advancement of technology, actively develop and utilize renewable and clean energy.Solar energy as clean energy has value in utilization, because it has more merits, such as extensive, environmental protection and permanent characteristics. Good conditions for use solar energy in China with abundant solar energy resources. Therefore, this article takes serpentine-flow flat-plate solar collector as research object. Hoping develop a kind of non-focused solar collector apply in organic Rankine cycle for power generation, refrigeration and air conditioning and other occasions through exploration and research.Flat-plate solar collector is a kind of non-condenser collector. It is widely applied because it have some merits, large light area, absorb direct and diffuse radiation of sun, low cost, withstand the pressure and not burst pipes, etc.Generally, common flat-plate solar collector is parallel to the flow. The working fluid of this collector very large and the flow temperature difference between import and export very small. Glass cover of this collector is single-layer glass and the insulation layer of bottom and side more thinly. It results in a large heat loss for collector and low thermal efficiency in high temperature section. So the type of this collector can only be used in low-temperature situations, application results in high temperature applications is not ideal, for example, solar organic Rankine cycle power generation, refrigeration and air conditioning, etc.The article established solar irradiance model to calculate the total irradiance of slope surface in cloudless day, and analyze the heat transfer process to energy balance, the radioactive transfer and the total heat loss coefficient of collector, etc. Then evaluate the performance of collector by exergy analysis in quality of energy. The results show that the flow rate and inlet temperature of working fluid common impact exergy. There is a best fluid inlet condition acquire maximal exergyThis article also describes design situation of serpentine-flow flat-plate solar collector and build situation of test platform. Through the collector instantaneous efficiency air drying test and test trials acquire following conclusions:1.Stagnation temperature of this collector can reach 170.2℃,temperature between heat-absorbing plate and environmental is 147.4℃, when solar irradiance is 1285W/m2. During the load test, temperature between import and export of heat-carrying fluid is 11.2℃,temperature between heat-absorbing plate and outlet of heat carrier fluid is 15.7℃when solar irradiance is 1137W/m2. These data support that collector in this experiment has good insulation properties.2.Instantaneous efficiency equation of this collector isη= 0.754-5.239(Ti-Ta)/I and heat loss coefficient of this collector is 5.239W/(m2℃) by fitting of the Instantaneous efficiency for collector.3. Flow rate have a great impact to instantaneous efficiency of the collector. Instantaneous efficiency of collector increase when flow rate of heat carrier fluid increase. Average instantaneous efficiency when flow rate of heat-carrying fluid is 190±10kg/h 8% higher than average instantaneous efficiency when flow rate of heat-carrying fluid is 115±15kg/h.4. Obtained measures to further improve the performance of collector through analysis of experimental data:a. Adjust the space between inner glass and outer glass of double-glass cover in order to reduce the heat loss of heat-absorbing plate to the environment by glass cover. b. Increase the flow rate of heat-carrying fluid and heat transfer coefficient of inner surface for copper tube in order to reduce thermal resistance between heat-absorbing plate and heat-carrying fluid. |
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