Since concentrated power generation by Stirling engine has the highest efficiency therefore efficient power generation by concentrated systems using a Stirling engine was a primary motive of this research.;A 1 kW Stirling engine was used to generate solar power using a Fresnel lens as a concentrator. Before operating On-Sun test, engine's performance test was conducted by combustion test. Propane gas with air was used to provide input heat to the Stirling Engine and 350W power was generated with 14% efficiency of the engine.;Two kinds of receivers were used for On-Sun test, first type was the Inconel tubes with trapped helium gas and the second one was the heat pipe. Heat pipe with sodium as a working fluid is considered the best approach to transfer the uniform heat from the receiver to the helium gas in the heater head of the engine.;A Number of On-Sun experiments were performed to generate the power. A minimum 1kW input power was required to generate power from the Stirling engine but it was concluded that the available Fresnel lens was not enough to provide sufficient input to the Stirling engine and hence engine was lagged to generate the solar power.;Later on, for a high energy input a Beam Down system was also used to concentrate the solar light on the heater head of the Stirling engine. Beam down solar system in Masdar City UAE, constructed in 2009 is a variation of central receiver plant with cassegrainian optics.;Around 1.5kW heat input was achieved from the Beam Down System and it was predicted that the engine receiver at beam down has the significant heat losses of about 900W. These high heat losses were the major hurdles to get the operating temperature (973K) of the heat pipes; hence power could not be generated even during the Beam Down test.;Experiments were also performed to find the most suitable Cavity Receiver configuration for maximum solar radiation utilizations by engine receiver. Dimensionless parameter aperture ration (AR=d/D) and aperture position (AP=H/D) were used to characterize the different configurations of Cavity Receiver and it was found that the Cavity Receiver with AR=0.5 and AP=0.53 has the maximum capability to utilize the solar heat to attain the maximum temperature of the heat pipe receiver. Experimental heat loss analysis at low temperature for different configurations of the cavity receiver was performed and air film temperature profiles along the wall height (H) of the cavity receiver were determined.;Since sodium heat pipes operate at high temperature (973K), there are huge possibilities of radiation and convection heat losses for direct solar heating of the heater head. Therefore mathematical modeling of heat loss analysis and its numerical solution at high temperature was also included in the research objectives.;2-D axisymmetric model with weakly compressible Navier Stokes equation and general heat conduction and convection equations were simultaneously solved using the finite element method approach. Computational fluid dynamics package COMSOL 3.5a was used as a numerical tool.;The temperature, and flow field pattern inside the cavity receiver were also visualized by means of surface contours. Heat loss analysis were performed for different configurations of Cavity Receiver and the numerical solution of different configuration showed that the aperture ratio (AR) plays a significant role for convection and radiation heat losses whereas the aperture position (AP) effects are negligible.
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机译：由于斯特林发动机的集中发电效率最高，因此使用斯特林发动机的集中系统进行高效发电是本研究的主要目的。1kW斯特林发动机用于使用菲涅耳透镜作为集中器来产生太阳能。在进行Sun-Sun测试之前，发动机的性能测试是通过燃烧测试进行的。丙烷气体和空气一起用于为斯特林发动机提供输入热量，并产生350W的功率，使发动机效率提高14％。；两种类型的接收器用于On-Sun测试，第一种是Inconel捕获氦气的管子第二个是热管。以钠为工作流体的热管被认为是将热量均匀地从接收器传递到发动机加热器头中的氦气的最佳方法。进行了多次On-Sun实验以产生动力。从斯特林发动机产生动力至少需要1kW的输入功率，但是得出的结论是，可用的菲涅耳透镜不足以为斯特林发动机提供足够的输入，因此发动机滞后了以产生太阳能。在高能量输入下，Beam Down系统还用于将太阳光聚集在斯特林发动机的加热器头上。阿联酋马斯达尔市的束射太阳能系统于2009年建成，是采用卡斯格拉尼光学系统的中央接收器工厂的一种变体;束射系统实现了约1.5kW的热输入，并且预计束射器的发动机接收器具有显着的效果。热损失约为900W。这些高热量损失是获得热管工作温度（973K）的主要障碍。因此，即使在Beam Down测试期间也无法产生功率。;还进行了实验，以找到最合适的腔体接收器配置，以最大程度地利用发动机接收器利用太阳辐射。使用无量纲参数孔径比（AR = d / D）和孔径位置（AP = H / D）来表征腔体接收器的不同配置，发现AR = 0.5和AP = 0.53的腔体接收器最大能够利用太阳能达到热管接收器的最高温度。对空腔接收器的不同配置进行了低温下的实验热损失分析，并确定了沿空腔接收器壁高（H）的气膜温度分布。;由于钠热管在高温（973K）下运行，因此存在直接加热加热器头的辐射和对流热损失的可能性很大。因此，高温下的热损失分析的数学模型及其数值解也被包括在研究目标之内。；采用有限元方法同时求解了具有弱可压缩Navier Stokes方程和一般热传导与对流方程的二维轴对称模型。 。计算流体动力学软件包COMSOL 3.5a用作数值工具。还通过表面轮廓显示了腔体接收器内部的温度和流场模式。对腔接收器的不同配置进行了热损失分析，不同配置的数值解表明，孔径比（AR）在对流和辐射热损失中起着重要作用，而孔径位置（AP）的影响可忽略不计。
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