| In the operation of the concentrator photovoltaic solar-thermal system,Concentrated battery temperature and flux density distribution inequality will be harmful to system thermoelectric performance. To solve the above problems, In this paper, the Fresnel lens, light funnel and prism is composed of high concentrated structure to enable light uniform distribution, which also had been optimized. Then, thermoelectric conversion model of the HCPV/T systems were established to analyze the influence of different factors on the thermoelectric performance,such as direct solar irradiance. Furthermore, In order to recycle waste heat of the system,as the driving heat source of membrane distillation,Factor analysis of its feasibility and practical operation of the system affect the thermoelectric properties are discussed. At last, the Fresnel concentrated HCPV/T system devices were experimental and researched. the main conclusions of this paper were as follows:1. High concentrated structure use non-uniform partitioning 4 focus Fresnel lens, Light funnel height 27 mm inclination of 82 °,Prism height is 55 mm inclination of 80.77 ° making its optical performance optimal. Compared with the Fresnel single-stage concentrated, its degree of homogeneity of 63.05% increased, acceptance Angle increases to 0.731 °.2. The photoelectric conversion efficiency of PV/T system was improved when the cooling water velocity was increased. While, the photoelectric conversion efficiency of the system was mainly constant when the cooling water velocity was beyond a certain value. However the tendency of the photothermal conversion efficiency of the system was increased firstly and then decreased with the increases of the cooling water velocity when the DNI was a constant, but it was increased with the increasing of the DNI when the cooling water velocity was invariable. When the DNI was 1000W/m2 and the cooling water velocity was 3.8m/s, the photothermal conversion efficiency of the system reached 43%. The value of the overall efficiency of solar thermal photovoltaic which less affected by the DNI was around 79.55% as the DNI increased from 200W/m2 to 1000W/ m2.3. Battery-chip temperature and thermal stress decreased with the increase of the cooling water flow rate, and the drop decreases with the increase of flow velocity, The layers of thermal stress in descending order of MgF2 layer structure, GaAs cell layer, Ge cell layer, GaInP cell layer; Cell chip layers of thermal stress were mutations appear in the X and Y directions at ± 3.78 mm, which was consistent with the position of the battery chip temperature drop. GaAs and Ge cell layer also mutations in the center position, the mutation point gradually disappear with the increase of cooling water flow rate; there were four point mutations in the battery chip thickness direction which GaInP cell layer 3, GaAs cell layer 1, MgF2 layer structure and the Ge cell layer without the mutation.4. The angle of incidence increases would exacerbate the degree of uneven spot, reduce the output power, and the photoelectric conversion efficiency of solar thermal conversion. Measured under the sun incidence Angle of 0 and 1 °, the system of photoelectric conversion efficiency maximum difference value is 5.67%, the minimum value of 2.87%. In order to ensure the uniform and efficient heat transfer, should make the Angle of incidence is lower than 0.3 °.5. Decrease the temperature of cooling water could reduce the cell chip temperature and thermal stress, help to increase the output power of devices and photoelectric conversion efficiency, The measured cooling water inlet water temperature of 14 ℃ and 20 ℃ respectively, the system output power difference between the mean of 0.75 W, photoelectric conversion efficiency is average of 2.73%... |
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