| The heliostat consists of a reflection mirror, the support frames, track drive systemsand control systems, which is the optical block of the tower solar thermal powergeneration. In the process of the heliostat tracking the sun, the focusing efficiency isaffected by many factors; when the heliostat is real-time tracking of the sun and gathersenergy, the structure acted on wind load is deformed and the tracking error affects thetracking structure position, which gather the sun’s radiant energy loss. But the influenceproduced by the wind loads and the tracking error is little discussed in the literature, toimprove the efficiency of the tower power generation system, it is particularly importantto study the effects of the heliostat condensing efficiency acted on the wind loads andthe tracking error.First, applying the basic knowledge of computational fluid dynamics analyzed thelaw that the wind load affected the heliostat in the summer solstice in the trackingprocess, which established the CFD model; FLUENT software was used to solve theheliostat model and obtained the wind-load value of each small area and analyzed windload distribution rule of heliostat mirror.Second, ABAQUS software was used for the finite element analysis of the heliostatstructure under the design of meeting the strength and stiffness requirements, andobtained stress/displacement diagram of the deformable mirror, which was known thatlarge deformation place of the heliostat structure under the impact of the wind loadmainly concentrated on the given mirror close to the ground place.Furthermore, after the analysis process, heliostat mirror deformation pointcoordinates were obtained under two influencing factors of the wind load and thetracking error, and using B-Spline surface interpolation reconstructed deformationsurface for the points; numerical difference method is used to solve the normal vector ofdeformation points, which combines with the normal vector of the incident light toobtain the path of the reflected light; Analyzing the positional relationship of thereflected light and the receiver obtains the reflection light loss and then heliostat mirrorconverging efficiency.Finally, the influence law of the heliostat condensing efficiency was analyzedunder two factors, the results show that: the wind loads have a greater impact on theheliostat focusing efficiency, under the influence of the azimuth and elevation angle, the focusing loss caused by the wind load is up to10%during13:00-16:00periods in thesummer solstice; tracking error also affected the heliostat concentrating efficiency, andthe condensing loss caused by tracking error at the azimuth is higher than at pitch angle.Through the above analysis, the results provide a reference not only to optimize thedesign and tracking programs chose for the heliostat structure, but also to providetheoretical support for the prediction and assessment of the focusing efficiency ofheliostat field. |
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