Showing papers on "Parabolic reflector published in 2022"

40 W Continuous Wave Ce:Nd:YAG Solar Laser through a Fused Silica Light Guide

Abstract: The solar laser power scaling potential of a side-pumped Ce:Nd:YAG solar laser through a rectangular fused silica light guide was investigated by using a 2 m diameter parabolic concentrator. The laser head was formed by the light guide and a V-shaped pump cavity to efficiently couple and redistribute the concentrated solar radiation from the parabolic mirror to a 4 mm diameter, 35 mm length Ce(0.1 at.%):Nd(1.1 at.%):YAG laser rod. The rectangular light guide ensured a homogeneous distribution of the solar radiation along the laser rod, allowing it to withstand highly concentrated solar energy. With the full collection area of the parabolic mirror, the maximum continuous wave (cw) solar laser power of 40 W was measured. This, to the best of our knowledge, corresponds to the highest cw laser power obtained from a Ce:Nd:YAG medium pumped by solar radiation, representing an enhancement of two times over that of the previous side-pumped Ce:Nd:YAG solar laser and 1.19 times over the highest Cr:Nd:YAG solar laser power with a rectangular light-guide. This research proved that, with an appropriate pumping configuration, the Ce:Nd:YAG medium is very promising for scaling solar laser output power to a higher level.

Solar Thermal Receivers—A Review

Abstract: This paper provides an overview of the different types of solar thermal receivers and their applications. The advantages of renewable energy-based systems are discussed first, followed by an analysis of the environmental issues associated with the use of conventional energy sources. An attempt is made to provide a historical overview of the uses of solar energy in the field of solar receivers, followed by a discussion of the various kinds of solar receivers, comprising a flat-plate receiver, compound parabolic receiver, evacuated tube, parabolic trough, parabolic dish, Fresnel lens, solar tower, Scheffler concentrator and field collectors. The main solar system element used for the solar receiver is also described.

Optical modeling of corrugation cavity receiver for large-aperture solar parabolic dish collector

Abstract: ABSTRACT 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.

Highly Efficient Solar Laser Pumping Using a Solar Concentrator Combining a Fresnel Lens and Modified Parabolic Mirror

Abstract: Solar-pumped lasers (SPLs) allow direct solar-to-laser power conversion, and hence, provide an opportunity to harness a renewable energy source. Herein, we report significant improvements in end-side-pumped solar laser collection efficiency and beam brightness using a novel 1.5-m-diameter compound solar concentrator combining a Fresnel lens and modified parabolic mirror. A key component of this scheme is the off-axis-focused parabolic mirror. An original dual-parabolic pump cavity is another feature. To determine the dependence of the SPL performance on the distance between the focus and central axis of the modified parabolic mirror, several systems with different distances were optimized using TracePro and ASLD software. It was numerically calculated that end-side pumping a 5-mm-diameter, 22-mm-long Nd:YAG crystal rod would generate 74.6 W of continuous-wave solar laser power at a collection efficiency of 42.2 W/m2, i.e., 1.1 times greater than the previous record value. Considering the laser beam quality, a brightness figure of 0.063 W was obtained, which is higher than that of other multimode SPL designs with end-side pumping. Thus, our SPL concentrator offers the possibility of achieving a beam quality as high as that obtainable via side pumping, alongside highly efficient energy conversion, which is characteristic to end-side pumping.

Performance Prediction and Optimization of Multi-Mirror Combined Solar Dish Collector

Abstract: An analytical method to calculate and optimize the performance of a multi-mirror combined solar dish collector is proposed in this work. It is based on the method of directly calculating the optical efficiency of a reflecting point, which can consider the influence of many factors. The distribution of the reflected solar intensity is obtained by the convolution of the actual solar intensity distribution and Gaussian distribution of the optical error. Then, the optical efficiency for a single mirror is calculated through integration over the total area of the mirror, and the method is validated by the SolTrace code. It is a rather quick method that reduces the amount of calculation and keeps high accuracy. The heat loss per unit area for the cavity receiver is assumed to be constant at a definite operation temperature for performance analysis and optimization. Taking a 62.25 m2 combined dish system with 249 square spherical mirrors as an example, the effects of system focal length, open radius of receiver, optical error, and focal length of the mirror on the system intercept factor and efficiency are studied. An optimization model is developed for maximizing the annual average net thermal efficiency. If the mirrors used have the same focal length for reducing the manufacture cost, when the optical error is 2 mrad, the net thermal efficiency and the intercept factor of the optimized system are 85.87% and 98.60%, respectively, while the concentration ratio is about 2000.

Analytic descriptions of parabolic X-ray mirrors

Abstract: On X-ray beamlines and telescopes, glancing-incidence mirrors with parabolic profiles are used to collimate, focus, and collect light. Here, analytic descriptions for paraboloidal, plane-parabolic, and parabolic cylindrical mirrors in several congruent geometries that are commonly used in fabrication, metrology, and modeling are provided. The exact expressions are derived directly from Fermat's principle, without coordinate transformations, in several mirror-centered coordinate systems, including one with the surface tangent to the central point of intersection. Coefficients for a sixth-order polynomial series approximation are calculated for that coordinate system.

Performance analysis of parabolic trough solar collector under varying optical errors

Abstract: ABSTRACT A typical parabolic trough solar field consists of a number of collectors that are made up of two main components: a parabola and a receiver. Various errors arise during the design/manufacturing, installation, and operation phases of the solar field. These errors influence the shape of the parabola as well as the alignment of the receiver. The present article aims to quantify the effect of these errors on the performance of a typical parabolic trough collector (PTC). To do so, a coupled optical-thermal model has been developed. The Monte Carlo Ray Tracing (MCRT) method is used to create and solve the optical model. The latter is then integrated with Computational Fluid Dynamics (CFD) to investigate the PTC’s thermal performance. The losses in performance induced by these errors are quantified. The analysis showed that small errors such as receiver dislocation or tracking error could induce a significant cut in the optical and overall performance. The loss in the optical efficiency due to tracking error of 16 mrad is about 50%. The error in the parabola profile can induce a reduction of 60% in the optical efficiency and up to 80% in the overall efficiency. A 0.05 m dislocation of the receiver can reduce the optical and overall efficiencies by about 37% and 49%, respectively. The results of the present study should support researchers and engineers in defining the optimum acceptable uncertainties through various phases of the design, manufacturing, and installation of the parabolic trough solar field.

Optimization of concentration performance at focal plane considering mirror refraction in parabolic trough concentrator

Abstract: ABSTRACT Parabolic trough solar thermal technology is the most cost-effective approach for concentrated solar energy applications. The concentrator thickness significantly affects the performance of the parabolic trough collector. To examine the effect of mirror refraction in the concentrator, the focal plane concentration for different concentrator thicknesses was studied using theoretical calculations, simulations, and experimental verification. A longitudinal offset of the focal plane is proposed to optimize the focal plane concentration. The deviation of the reflected sunlight depending on the concentrator thickness was found to strongly affect the concentration in the focal plane. When the concentrator thickness was increased by a factor of 5, the focal plane was 5 times as wide, the maximum energy flux density in the focal plane decreased by a factor of 5, and the optical efficiency decreased by 0.24%. The longitudinal offset of the absorber plane position was introduced to avoid local overheating of the absorber and low collector temperature by maintaining the focal plane width and maximum energy flux density in the focal plane within appropriate ranges. The experimental results showed that with optimization, the maximum energy flux density, uniformity, and optical efficiency increased by 5.75%, 3.35%, and 2.43%, respectively.

A comprehensive review on performance assessment of solar cavity receiver with parabolic dish collector

Abstract: ABSTRACT 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 using nano-fluid and for pure thermal oil. The hemispherical cavity receiver has shown the daily mean thermal efficiency of using novel soybean oil-based MXene nanofluid. Under the constant parameters, and solar irradiation intensity 300 to 1100 , 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%.

Numerical Comparison of Elliptical and Conical Cavity Receiver of Solar Parabolic Dish Collector System

Abstract: The solar parabolic dish collector system is ace of the concentrated solar power technologies. It attracts researchers all around the globe because of its higher thermal conversion efficiency. The cavity receivers play a major role in bettering the overall solar collector efficiency by reducing the heat losses. With minimum heat losses, the employment of the concentrated power increases. This current study compares two types of cavity receivers such as elliptical and conical through numerical simulations and determines the heat loss coefficient. The combinations of various parameters such as temperature (673 K, 773 K, 873 K, 973 K, and 1073 K), orientation (0°, 30°, 45°, 60°, and 90°), and aspect ratio (1.5, 1.75, 2.0, 2.25, 2.5) of the cavity receivers were considered for the simulation. The conical cavity receiver has less heat loss coefficient than the elliptical cavity receiver. Among the different combinations of parameters, the heat loss at 0° inclination of conical cavity receiver is 31% less than at 90° for 673 K and others.

Steam and electrical power generation by a hybrid photovoltaic/parabolic dish concentrator using beam splitter technology

Abstract: The parabolic dish is considered the most performant concentrating solar power (CSP) technology since it fits a wide range of domestic and industrial processes and offers better modular deployment than other CSP technologies such as thermal power receivers. The parabolic dish has been widely employed to produce steam and electricity especially when it works in conjunction with Stirling engines; however, the extreme complexity of the latter makes the power generation cost of this technology unfavorable against other competing solutions. In this paper, a comprehensive and detailed optical and thermal performance analysis and optimization study of a hybrid photovoltaic/parabolic dish concentrator with a conical thermal receiver using a beam splitter filter (PV/PDC‐CTR‐BSF) are carried out. A complete modeling module is developed to assess and optimize the overall yields of the PV/PDC‐CTR‐BSF. The present work is unique since it encompasses a sophisticated simulation tool enabling performance potential assessment of a novel PV/PDC‐CTR‐BSF system coupled with a novel conical‐shaped helical coiled‐tube heat exchanger for steam production and paves the avenue for higher electrical yield using single‐junction PV cells mounted over the tip surface area of the paraboloid mirrors. The concentrated solar density (CSD) distribution, optical efficiency, temperature distribution, and steam fraction have particular interest in the performance assessment of the innovative PV/PDC‐CTR‐BSF package system. As a result, the maximum value of the CSD at the conical cavity receiver and the PV cells is 40 and 8 kW/m2, respectively. The optical efficiency of the proposed design has a breakthrough in the record of the typical hybrid designs reaching the value of 67%. Moreover, the maximum surface solar cells temperature was 80°C, while the temperature reached 170°C at the conical cavity receiver. The optical new hybrid design has maximized the steam productivity up to a steam volume fraction of 98%.

Recent Developments in the Thermal Performance of Flat Plate Solar Water Heaters with Reflectors-A Review

Abstract: ABSTRACT One of the most extensively used forms of energy is solar energy. It is a widely utilized, low-cost, eco-friendly, sustainable, emission-free renewable energy source, and it reduces power costs from coal, electricity, and other sources. Solar energy is utilized for several reasons, such as water heating in homes and industrial applications using solar collectors. Unlike other solar collector energy applications, flat plate solar collector techniques for water heating offer low maintenance and operational expenses. This article reviewed the innovations of flat plate solar collectors for improved thermal performance with reflectors in solar water heaters. The impact of combining flat plate solar collectors and reflectors for thermal performance improvements is discussed in this article. Integrating flat plate solar collectors using reflectors is an effective and cost-effective approach among the numerous geometries utilized for thermal performance improvements. In order to improve SWH performance, researchers have implemented a number of modifications so far. These modifications are associated with various types of reflector integration in SWH such as booster mirror reflector, plane reflector, side reflector, bottom reflector, top-edge reflector, inclination angle of reflector, gap between reflector and collector, trapezoidal reflector, parabolic reflector, polyline reflector etc. The major goal of this paper is to evaluate several studies wherein different reflectors have already been utilized to improve thermal performance and to recommend a design for the best performance. Furthermore, the research gap has been identified, along with suggested upgrades for future study, which should benefit researchers in extending the growth of this technology.

Study of Cassegrain-type antenna for radio telescope

Abstract: There are many critical parameters in the design of a radio telescope, such as antenna gain and antenna resolution. In telecommunications, radar, and radio telescopes, an antenna is a very important component. There are many designs of the antenna, such as dipole array and parabolic antenna. Parabolic antennas also have many sub-reflector and antenna methods that control the radio wave, such as the Cassegrain type. A Cassegrain-type antenna is a parabolic antenna in which the feed antenna is mounted at or behind the surface of the main parabolic reflector dish. For the transmitter system, the beam of radio waves from the feed antenna illuminates the secondary reflector (sub-reflector), which reflects it back to the main reflector dish and then forward to space. The Cassegrain design is widely used in parabolic antennas, for large antennas in satellite ground stations, communication satellites, and radio telescopes. In this paper discusses the design of a Cassegrain-type antenna for radio telescope, basic calculation, diameter size of the main reflector of 20 meters, the diameter size of sub-reflector of 2.5 meters, and frequency of 22 GHz and 43 GHz.

Feasibility of stereophonic projection lithography applying a parabolic magic mirror system

Abstract: A new stereophonic projection lithography applying a parabolic magic mirror system was proposed. An aperture was also opened at the bottom of lower mirror, and a transparent reticle was placed in place of a reflective object article used in the conventional magic mirror system. Toward the transparent reticle, illumination light was irradiated obliquely upward from the bottom. Thus, images of curved reticle patterns were projected at the aperture center of the upper mirror, and 200 μm line-and-space resist patterns were actually printed on a silicon wafer when a flat reticle was used. On the other hand, it was clarified by tracing light rays in the meridional plane that the resolution depended on the field size, the extent of used mirror parts, and the defocus. It is considered that aimed 50 μm patterns will be printable if the illumination system is improved. The new method is feasible and hopeful.

Development and thermal performance evaluation of solar parabolic dish based on fiber‐reinforced plastic

Abstract: This paper illustrates the design and fabrication of a 76° rim angle solar parabolic dish concentrator with low cost based on fiberglass‐reinforced for heating of heat transfer fluid using the hand layup process. Numerous advantages of fiberglass material include corrosion resistance, lightweight, design flexibility, quick installation time, and low cost makes it suitable for fabrication. The concave surface on which the reflective sheets are mounted is made to a high degree of perfection. The design process, as well as the complete fabrication process, are elaborately discussed in this article. The thermal efficiency of the newly constructed fiberglass‐reinforced solar parabolic dish concentrator was assessed by heating the heat transfer fluid in the conical cavity receiver, which was cycled from the sump via a gear pump and flexible stainless steel connecting pipes. The maximum value of heat transfer fluid temperature achieved was 194°C at the sump. The average thermal efficiency achieved for indoor heating at the sump was 17.42%, 17.16%, and 17.21%, respectively, during Experiments 1, 2, and 3. The results indicate that this system is acceptable for indoor cooking in the kitchen, as the system achieves temperatures between 150°C and 194°C.

Comparison Between CSP Systems and Effect of Different Heat Transfer Fluids on the Performance

Abstract: While fossil fuel sources have declined and energy demand has increased, in addition to the climate change crisis, the world turned to using renewable energies to get its energy. Concentrated solar power (CSP) is one of the main technologies used for this purpose. This study aims to compare the different concentrated solar power technologies in terms of their efficiency, cost, concentration ratio, and receiver temperature. Results showed that technologies were arranged according to temperatures from high to low as follows; the parabolic dish reflector, central receiver collector, linear Fresnel reflector, and parabolic trough collector. According to cost, the parabolic dish reflector has the highest price, while the linear Fresnel reflector has the lowest price. Also, the parabolic dish reflector has the highest efficiency among the others, followed by the central receiver collector, then the linear Fresnel reflector, and the parabolic trough collector respectively. Additionally; the study represented that point-focus devices have a high percentage of concentration ratio than line-focus devices. Finally, in order to exploit these sources throughout the day, it is recommended to use phase change materials to store the excess thermal energy as a positive and effective approach to solving the energy problems.

Designing of Parabolic Trough Collector using Plane Mirrors

Abstract: Parabolic trough collectors are used for concentrating solar radiation along the focal line. These collectors are commercially used for power generation. Approximately thirty-seven percent of the total cost is attributed to the solar field. In order to increase the economic viability of solar thermal power plants, there is a need to reduce the cost of solar thermal collectors. In this paper, an attempt has been made to reduce the cost of parabolic trough collectors by fabricating them using plane mirrors. In this endeavor, all factors which affect the surface area of the collector have been identified and the impact of rim angle on the surface area of the collector has been studied. It has been observed that surface area decreases sharply with an increase in rim angle from 20-60 and beyond this value, there is a negligible increase in surface area. Thus, a parabolic trough with aperture width 0.5m, length 0.95m, and rim angle of 96 has been considered for designing a parabolic trough collector using plane mirrors. It has been observed that the use of plane mirrors in place of curved mirrors significantly reduces the cost of manufacturing by 83.33 percent and will give a major boost to the large-scale installation of solar thermal power plants.

Prediction of focal image for solar parabolic dish concentrator with square facets—an analytical model

Abstract: Solar parabolic dish concentrator is one of the high-temperature applications of more than 400 °C for thermal and electrical power generation. In the solar parabolic dish concentrator, the arrangement of reflectors over the surface area is the significant factor for effective concentration of solar radiation. Also, focal image is one of the most influencing parameters in the design of receiver. Among the various reflectors, the square-shaped reflectors (facets) are comparatively effective in converging the incoming radiations to attain better focal image. In this regard, an attempt has been made to predict the focal image diameter of a solar parabolic dish concentrator with a square facet of different influencing parameters using a novel mathematical model. The influencing parameters considered for the study are aperture diameter, rim angle, and facet length of the dish concentrator. Using the model, the focal image dimension and aperture area of a solar parabolic dish concentrator with square facets can be predicted accurately for efficient design of a solar parabolic dish collector system. Finally, the model is validated with the experimentally obtained focal image diameter. The current model is in good agreement with the experimental value, with a deviation of 8.84%. Hence, the proposed model can be used for the design of parabolic dish systems.

Optical Efficiency of Semi-parabolic Linear Fresnel Reflector System “SPLFR”

Abstract: One of the developed technologies in the solar energy field is Concentrated Solar thermal (CST) which is favorable to be deployed in Tunisia. Although Parabolic Trough Collector (PTC) is the most advanced, reliable and extensively used technology, Tunisia faces challenges to put it into use due to its expensive cost. Manufacturing a conventional PTC system locally requires a high-tech for float glass mirrors. There are numerous studies which investigate alternative designs for different PTC configurations, in order to have an acceptable optical and thermal efficiency and a reduction in the manufacturing cost via local construction. The used optical modification on PTC reflector, based on shaped strip mirrors on a discretized parabola, leads to a Semi Parabolic Linear Fresnel Reflector (SPLFR) design. The aim of this paper was to perform an optical design for an SPLFR to be set up in Tunisia and compared to a classic PTC with an inox sheet reflector using geometrical and ray tracing techniques. The findings show that stretched-shape of strip mirrors is more affected by conventional errors specially tracking ones. Nevertheless, this model provides an acceptable optical efficiency at a low cost, simple and locally manufactured.