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A thermodynamic analysis was performed on a newly developed concentrated solar power (CSP) technology known as the Cross-Linear (CL), which addresses the issue of cosine loss in conventional CSP technology. The analytical model has been developed and validated using experimental data collected at the experimental site situated in Bhopal, India. The analysis was performed under direct normal irradiance of 775 W/m2 with the key objective to determine the optimum inlet condition of the heat transfer fluid (HTF) considering three optimization parameters: HTF outlet temperature, energy, and exergy efficiency of the receiver. Also, the exergy of the solar field is investigated depending on the available solar irradiation throughout the day for three different configurations of the heliostat field. After a comprehensive analysis of the results, the optimal air inlet temperature range was observed to be between 373 and 423 K, and the optimal air mass flow rate was overserved to be 0.0925 kg/s (333 kg/h), which provides energy and exergy efficiency values within 50% to 60% and 28% to 34%, respectively. The maximum electrical exergy efficiency for 30 kW plant capacity is observed to be around 70% at solar noon with a cosine factor of around 0.9 for 4-hour duration. [ABSTRACT FROM AUTHOR]

Improving the overall performance of parabolic trough collectors (PTCs) represents the best method to reduce the cost of energy produced. The goal is to increase their potential to generate more useful heat, particularly at high ranges of temperatures. Therefore, various techniques have been thoroughly examined in the literature. Indeed, the non-uniform heat flux on the PTC receivers induces overheating of the absorber tube and significant thermal stress, which requires the use of expensive materials. It also reduces the overall thermal performance of the system. To overcome these issues, practical solutions must be introduced. In this paper, integrated spherical pins are used and different configurations have been proposed and investigated. To do so, a numerical model that combines optical and thermal aspects has been developed. For this, the Monte Carlo ray tracing technique (MCRT) is coupled with the finite volume method (FVM). Also, experimental tests on the MicroSol-R platform have been used to validate the numerical models. A number of energetic and exergetic performance indices are used to analyze the potential improvements due to the use of spherical pins. The analysis showed that the use of pins increases the heat transfer coefficient by up to 27.2% and reduces the heat loss by up to 9.32% compared with conventional smooth tubes. Moreover, it is found that the performance evaluation criterion (PEC) can be enhanced by up to 24.92%. Consequently, when using a solar receiver with five pins (which was selected as the best configuration among the examined configurations), the overall efficiency and the exergetic efficiency are increased by up to 4.1% and 2.2%, respectively. Indeed, the use of pins inside the solar receiver is a practical solution to improve the efficiency of the PTC system and has the potential to reduce the thermal stress on the receiver thanks to the high heat transfer coefficient. It also helps prevent overheating and reduce thermal losses by keeping the maximum temperature within a suitable operational range. [ABSTRACT FROM AUTHOR]

Cavity receiver integrated with parabolic dish collector is an essential component of the solar thermal energy conversion process for high-temperature applications, such as power generations, process heat demand, and industrial applications. This paper is focused on a comprehensive review and representation of research on solar cavity receiver. The majority of research concentrated on the highest thermal efficiency with the least amount of heat loss and their interactions with solar cavity receiver geometries. The review consists of various combinations of the receiver's geometries along with different heat transfer fluids, and it also give suggestions to improve the performance of the system based on optimized geometrical and operational parameters. The existing literature primarily focused on the experimental and numerical procedures used with different technologies to improve the efficiency of the solar power system. The decrements in heat losses experienced during the conversion of solar energy into thermal energy is used to determine the efficiency of parabolic dish collector systems. The evaluation of convection and radiation losses is essential to improve the thermal performance of the solar power system. Heat loss models and correlations have been discussed to understand the heat loss mechanism for cavity receiver. The present study analyzes a wide range of parameters that affect cavity receiver performance, including aspect ratio, concentration ratio, optimum receiver length, receiver aperture, tilt angle, and inclination angle. The benefits of air curtains, receiver coatings, and other heat transfer enhancement techniques are also briefly reviewed and expected to be useful in modeling and design of cavity receiver with parabolic dish collector system to improve overall performance. One of the most significant aspects of this article is that it covers a wide range of cavity literature encountered in other engineering systems, power generation, and a wide range of other industrial and domestic applications. The cylindrical cavity receiver has shown an average thermal efficiency of 63.9 % using nano-fluid and 56.44 % for pure thermal oil. The hemispherical cavity receiver has shown the daily mean thermal efficiency of 82.66 % using novel soybean oil-based MXene nanofluid. Under the constant parameters, and solar irradiation intensity 300 to 1100 W / m 2 , the receiver thermal efficiency varies from 80% to 90%. In case of conical cavity receiver, the maximum thermal efficiency achieved with thermal oil is 78.7%. [ABSTRACT FROM AUTHOR]

This article presents an optical investigation of a corrugation cavity receiver for a 100 m2 parabolic dish collector (PDC). The performance of PDC depends on the selection of the receiver and its mounting distance from the collector base (H) to receive a high amount of reflected radiation. This work performs optical modeling for PDC with a designed corrugation cavity receiver using commercial software, ASAP® 2013. The motivation for this study is derived from the fact that the entrapped internal reflection within the receiver optimizes the system's optical efficiency. The receiver geometry is such that it attributes to increasing internal reflection and average heat flux intensification. The present optical model is validated with the available literature. The influential geometrical and optical parameters of the receiver have been optimized by simulation by varying the aperture diameter (da,r) from 0.504 to 0.604 m, surface absorptivity (α) from 75 to 95%, receiver coil's outer and inner pitch (Po and Pi) from 0.00667 to 0.00909 m, and angle of taper (θi) from 50° to 56° for H = 5.35–5.65 m. The performance of the optimized receiver is compared with the conical cavity receiver and is found to be excellent among all values of H. This optical modeling can be expected to be helpful for engineers and researchers in designing the optimized optical receiver for solar parabolic dish collector systems. [ABSTRACT FROM AUTHOR]

This paper is related to the solar radiation concentrating at two focus points, at which three stages of receivers are located. It refers to the improvement of the thermal collection efficiency of the parabolic dish concentrator (PDC) system by using a twin-staged concentrator and three-staged receiver system. It discloses system design that concentrates the incident solar energy in varying proportions subsequently at low-, medium-, and high-temperature solar cavity receiver stages. It is seen that the modified design demonstrated increased thermal collection efficiency as compared to the conventional single-stage system. It improved the system efficiency by about 12.4% for lesser flow Reynolds number (Re). For the entire studied flow range, the average percentage increase in system thermal efficiency is about 8.6%. The twin-stage system demonstrated insignificant improvement in the flow transition zone. In the case of a developed system, the percentage contributions of losses by conduction, convection, and radiation are varying from 1.5–2.7%, 59–62%, and 36–37%, respectively. [ABSTRACT FROM AUTHOR]