| With the energy crisis continues to approach,the world's energy structure will also have a new change,high consumption of traditional energy will be gradually replaced by recyclable energy.As the most basic resources in the energy structure,solar energy will usher in new development.For solar thermal system,the main problem of technology development is economy and stability,therefore,we must improve thermal efficiency,reduce costs to develop solar thermal technology.In this paper,the concept of "energy saving and environmental protection" is regarded as the guiding ideology and the distributed natural circulation Linear Fresnel Reflector system is defined as the research object,then I proposes a distributed collector system structure which is integrated with the building,and can futher used in industrial and agricultural production of medium-temperature steam solar thermal system.A 5kW distributed natural circulation Linear Fresnel Reflector solar medium-temperature system structure has been designed,the main parameters such as CPC composite condenser and mirror field arrangement are calculated,the ratio of CPC is 2.48,the ratio of system is 19.9,then the optical efficiency of the system is dissected by Tracepro optical analysis software.At the summer solstice,the theoretical average irradiance intensity of the collector tube is 1.9×104 W/m2 and the maximum irradiance intensity is 2.4×104 W/m2.As the system structure and optical parameters has been determined,the heating state of the straight-tube is further simulated,the wall temperature of straight-tube was obtained at different circulation rate;comparing the temperature at different circulation rate in natural circulation and forced circulation,the forced circulation rate is greater than natural circulation at the same temperature,then the design requirements of the system are determined.The feasibility of the system analysis is further demonstrated.In order to analyze the difference between theory and experiment,a 5kW distributed natural circulation Linear Fresnel Reflector solar medium-temperature system experimental platform was set up.in order to understand the thermal performance of natural circulation Linear Fresnel Reflector systems,a series of experiment has be conduct to study the effects of main factors on the operation of system,such as heat loss,filling factor,etc.the experimental results are as follow: the mean relative error of solar radiation intensity between calculatesd value and the actual is 20.5%,the dynamic pressure of this natural circulation system is 3675.308 Pa,the minimum irradiation condition of the system to complete the natural circulation is 350~450 W/m2,The maximum temperature of the steam is 128.99?,the maximum pressure is 0.3 MPa in the experiment,the efficiency of the experimental system is 0.317 on April 15 th. |
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