High Density Thermophotovoltaic Generation of Electricity using Near-Field Radiation

本文研究了近场辐射（倏逝波）对热光伏发电的增强效应。在真空室中，将钨极发射极和GaSb TPV电池面对面地放在一起。电池粘贴在安装在x-y-z-θ微级上的水冷铜块表面，而发射器由安装在计算机控制的双轴角级上的水冷套中的两个氧化锆环保持。利用角锥级，在这些表面之间的平行间隙在发射器的表面积上形成，即2 x 8 mm^2。空间分辨率为100nm，取决于z轴平台的最小增量运动。用CO_2激光器对发射极进行加热。输入能量保持恒定，即20W。发射极的温度由热电偶测量。当间隙减小到15μm时，获得的电功率首先增加，然后几乎保持不变。结果表明，当间隙小于50μm时，观察因子基本一致。当间隙进一步减小时，发射极温度急剧下降。在温度继续下降的情况下，电功率先相应减少，然后相反增加。最后，功率急剧下降到几乎为零，这意味着发射极已经与电池接触。根据接触点原点的刻度，功率和温度随间隙的变化可以理解如下。当发射器接近电池时，长波辐射的近场效应首先变得显著。在这种情况下，只有热量被快速传递，导致温度急剧下降。当间隙小于1μm时，波长在可见光到1.85μm范围内的辐射被TPV电池主动转化为电能，因此短波辐射的近场效应逐渐显著。因此，公开了近场辐射增强了传热以及从热能到电能的能量转换。少

Effect of near-field radiation (evanescent wave) to enhancement of thermophotovoltaic(TPV) generation of electricity has been investigated in the current study. A tungsten emitter and the GaSb TPV cell were put together in face to face in a vacuum chamber. The cell was pasted on a surface of a water-cooled copper block mounted on x-y-z-θ micro-stages, while the emitter is held by two zirconia rings in a water-cooled jacket mounted on double axes gonio-stage controlled by a computer. Using the gonio-stage, a parallel gap between these surfaces was made over the surface area of emitter, i.e., 2 x 8 mm^2. The space resolution, which depends on the minimum incremental motion of the z-axis stage, is 100nm. A CO_2 laser is used for heating of the emitter. The input energy is kept at constant, i.e., 20W. Temperatures of the emitter are measured by thermocouples. As the gap becomes narrower up to 15μm, the electric power obtained, first, increases, and then, is held at almost constant. As a re … More sult, the view factor is almost unity under the condition of the gap narrower than 50μm. On further decrease in gap, the emitter temperature decreases drastically. The electric power, first, decreases accordingly, and then, increases oppositely though the temperature still continues to decrease. Finally, the power went down sharply to almost zero, which means that the emitter has contacted with the cell. On the basis of the scale from the origin at the contact point, variation of the power and the temperature with gap is understood as follows. As the emitter approaches the cell, the near-field effect for long wavelength radiation becomes remarkable, first. In this case, only the heat is transferred quickly, resulting in the drastic temperature decrease. As the gap is narrower than 1μm, the near-field effect for short wavelength radiation becomes remarkable gradually since the radiation with wavelength in a range from visible to 1.85μm is active for conversion into electricity by the TPV cell. Consequently, it is disclosed that the near-field radiation enhances heat transfer as well as energy conversion from the thermal energy into electricity. Less