Showing papers on "Parabolic reflector published in 2023"

Investigation of the characteristics of a deployable space mirror antenna with a sparse reflecting surface

Abstract: The article presents the results of a study of the characteristics of a space parabolic mirror with a deployable reflector. A model of the reflector truss structure formed by two asymmetric parabolic networks with tension cables is presented. Three variants of the sparse structure of the reflecting film of the reflector are presented, differing in periodically repeating hexagonal holes with different sizes. A complex electrodynamic modeling of the radiation characteristics of a parabolic mirror antenna with a developed model of a truss-bearing structure and the proposed structures of reflective films, allowing to reduce the mass of the reflector and increase the reliability of the antenna system, are carried out. The estimation of the frequency dependences of the characteristics of the variants of the parabolic mirror antenna model is given. Recommendations on the use of sparse reflective films for small, medium and large apertures of deployable reflectors are proposed.

A simplified opto-thermal assessment and economic study of parabolic dish solar concentrator pondering on the receiver position induced uncertainties

Abstract: This paper investigates the opto-thermal and economic assessment of low-cost solar parabolic dish concentrators (PDC), focusing on the receiver position-induced uncertainties. An optical model of the proposed PDC system is developed in Tonatiuh optical simulation tool. The optical analysis is conducted by the Monte Carlo Ray Tracing method for different vertical and horizontal positions of the PDC’s receiver. In addition, An experimental test rig based on a locally manufactured PDC with a low-cost reflecting surface made of aluminum reflector foil is developed to achieve the purpose of this work. A cavity receiver made of a cylindrical-cone brass tube is used and tested under different positions of the focal point of the PDC. The impact of the uncertainties on the performance of the proposed PDC is experimentally estimated. A relatively simple mathematical model is utilized to evaluate the thermal and exergy performance for the different positions of the cavity receiver. The results showed that the proposed PDC could generate hot water at temperatures 77°C, 64°C, and 55°C for the three focal point positions, respectively. The collector efficiency of the PDC-cavity receiver system in the receiver position 1, 2, and 3 were 70.2%, 53.2%, and 24 % while the average values of exergy efficiency for the PDC at the receiver positions were 4.7%, 2.3%, and 0.93% respectively. This clearly shows the effect of the receiver positions on the performance of the parabolic dish solar concentrator and justifies the requirement of appropriate positioning of the receiver for the parabolic dishes.

Optical modeling of a cylindrical-hemispherical receiver for parabolic dish concentrator

Abstract: Among all sub-systems of a solar thermal energy system, the receiver plays a significant role when it gets heat energy from the concentrator. The reliability of such systems depends on the amount of solar energy that the receiver collects and other optical parameters like focal length, aperture diameter, surface absorptivity, and slope error. The present paper discusses the optical analysis of a cylindrical-hemispherical receiver coupled with a parabolic dish concentrator having 3-m diameter. The study has been carried out using the SolTrace software by varying the parameters like receiver aperture diameter (Da) ranging from 0.125 to 0.162 m, surface error of the concentrator varying from 1.7453 to 34.907 mrad, and also surface absorptivity (α) changing from 75 to 95% for different receiver distances (H) ranging from 1.7 to 1.95 m. The simulation results show that the optical efficiency is maximum when the receiver with 0.150-m aperture diameter is placed at a distance of 1.85 m from the concentrator. An increase in slope errors from 1.7453 to 17.453 mrad decreases the average optical efficiency by almost 50% for all receiver diameters. It is also noticed that uniform heat flux distribution can be achieved when the receiver’s position is maintained at H = 1.85 m from the concentrator for 0.150-m receiver diameter and 95% absorptivity of the receiver surface. The simulated results of heat flux intensity on the receiver surface are then compared and validated by the experimental results available in the literature. The simulated optical efficiency of the present receiver is found to be 8% higher when compared with a conventional cylindrical receiver with similar dimensions.

Performance analysis of parabolic dish solar cooking system with improved receiver designs

Abstract: Lack of access to clean energy for cooking and heating applications is one of the challenges faced by households in developing countries. Solar cooking is one of the solutions, but suffers low adoption and utilization due to various challenges including technical limitation. This study investigated initiatives on improving the technical viability of parabolic dish solar system used for direct cooking by focusing on the receiver. Three receiver prototypes namely; Insulated, Oil-filled and Air-filled, all incorporated with a base circular ring, were constructed and their performance was compared experimentally with the conventional receiver. The maximum temperature inside cooking vessels were 154 °C, 99 °C, 141 °C and 128 °C while standardized stagnation temperature and first figure of merit (F1) were found to be 159 °C, 100 °C, 154 °C and 109 °C; and 0.26, 0.15, 0.54 and 0.17, for systems with insulated receiver, oil-filled receiver, air-filled receiver, and conventional receiver, respectively. The second figure of merit (F2), overall heat loss factor, heat exchange factor and optical efficiency were determined as 0.36, 0.15, 0.14 and 0.33; 59.7 W/m2 K, 28.6 W/m2 K, 20.49 W/m2 K and 73.4 W/m2 K; 0.18, 0.75, 0.69 and 0.23; 25%, 4%, 4% and 17%. The study found that the cooking system with Insulated Receiver gave more merits and was established as the best.

Experimental Investigation of Absorber Design on the Performance of a Solar Tracking Distillation System

Abstract: The problem of water scarcity, especially in North Africa and Libya, has been reviewed. A distillation apparatus has been proposed that uses solar energy as a source of unlimited energy. It should be noted that most countries in North Africa to a relatively favourable area between 35° north latitude and 37° south latitude. Because of this, they can rely on sunlight as an unwavering source of fresh water. The setup used in the experiment uses a solar parabolic concentrator, which collects solar radiation and concentrates it on an evaporator. The parabolic reflector increases the amount of incoming solar radiation and its concentration on the evaporator, thereby increasing the heat output and production rate of the solar still, thereby increasing the efficiency of the solar still. The suggested distillation unit-body consists of a parabolic reflector, an evaporator (Tube absorber) which was placed on the focal line of the parabolic reflector, and a pyramidal glass frame that acts as a condenser. Motors and electronics that expose the reflector to the sun's rays throughout the day from sunrise to sunset. The results show that increases in solar intensity, ambient temperature, and evaporation area increase specific productivity. Using the tracking system as an automatic control unit to make the reflector the sun rays all over the day from sunrise to sunset.

Design and Experimental Analysis of Parabolic Dish Solar Cooker at Different Climatic Conditions

Abstract: Solar energy is a renewable energy source that is abundantly available in Pakistan. Solar energy is a green energy that contributes to cater the adverse effects of conventional energy sources on environment. A parabolic dish solar cooker is designed to utilize solar heat energy for cooking purposes. Solar cooker comprises mainly of a reflective concentrator and a receiver pot. Greenhouse effect is applied by placing a glass jacket around the receiver pot that aid in rise of receiver temperature and cater for ambient effects on receiver. Performance of the parabolic dish solar cooker is analyzed at two different locations of Pakistan (Islamabad and Multan). The experimental results indicate that solar flux and effective concentration of solar irradiance has major contribution in PDSC performance. Also, it is concluded that time required for attaining high temperature i.e., (90°C) 363.15 K in Multan is 30 minutes less compared to Islamabad due to variable ambient conditions. Similarly, the amount of heat energy stored by water and the heat energy readily available during cooking i.e., cooking power is more in Multan scenario comparing it with Islamabad. From the results obtained it is concluded that PDSC has a great potential to be used as an alternative to conventional cooking methods.

Solar-pumped fiber laser using a solid-state luminescent solar collector

Abstract: We have developed a fully planar solar-pumped fiber laser using a solid-state luminescent solar collector (LSC). This laser does not use any focusing device, such as a lens or mirror; thus, it can lase without tracking the sun. Our developed device with an aperture of 30 cm emits 15 mW, corresponding to an optical-to-optical conversion efficiency of 0.023% and a collection efficiency of 0.21 W/m2. A 12-fold improvement over a previously developed liquid LSC is achieved by combining the total internal reflection of the solid-state LSC with dielectric multilayer mirrors. The observed laser power is in good agreement with that predicted via numerical simulation, demonstrating the effectiveness of our proposed method.

Thermal Analysis of Multi Reflector Compound Parabolic Collector (MRCPC)

Abstract: Thermal analysis of multi reflector compound parabolic collector (MRCPC) has been presented in this paper. Compared to the existing parabolic trough collector, MRCPC has two upper compound parabolic concentrators and a bottom parabolic trough concentrator joined by two parallel plane mirrors. In this work, an attempt has been made to get the optimum value of different parameters, such as flow rate, collector’s length and absorber tube diameter based on the given conditions. Simulation is done using the meteorological data of Jalandhar, India on 16th March 2022 from 6 a.m. IST to 6 p.m. IST. Optimum values are taken based on the conditions based on the properties of heat transfer fluid flowing inside the absorber tube which is water for the present study. Results have been obtained using numerical computation using MATLAB. Outcomes also show that with an increase in flow rate, efficiency increases and tube outlet temperature decreases, with an increase in collector’s length, efficiency decreases and outlet temperature increases and with an increase in absorber tube diameter both efficiency and fluid outlet temperature decreases.

Research of the Characteristics of the Parabolic Reflector during Its Natural Oscillations

Abstract: The study considered the degree of reduction in the efficiency parameters of a parabolic reflector caused by free vibrations. Estimates of the research results for various types of amplitude functions are given. It was discovered that the most negative reduction in efficiency is caused by low frequency oscillations. This leads to strong changes in the distribution of surface currents and the strength of the electromagnetic field at the focus of the reflector. It has also been found that the properties of an oscillating reflector change to a lesser extent if the amplitude function is characterized by a high density of nodes and antinodes.

Adaptive parabolic membrane mirrors for large deployable space telescopes.

Abstract: A key element for the development of extremely large telescopes in space or balloon-borne observatories will be a reduction in the areal weight of the primary mirror. Large membrane mirrors offer a very low areal weight but are difficult to manufacture with the optical quality needed for astronomical telescopes. This paper demonstrates a practical method to overcome this limitation. In a test chamber we have successfully grown optical quality parabolic membrane mirrors on a rotating liquid in a test chamber. These polymer mirror prototypes of up to 30 cm in diameter show a sufficiently low surface roughness and can be coated with reflective layers. By manipulating the parabolic shape locally using radiative adaptive optics methods, it is shown that imperfections or changes in the shape can be corrected. With only tiny local temperature changes induced by the radiation, many micrometers of stroke have been achieved. Scaling the method investigated to produce mirrors with diameters of many meters is possible using available technology. This approach opens the possibility to produce affordable extremely large primary mirrors for space telescopes. With the flexibility of the membrane material, this type of mirror can be compactly rolled up when stored in the launch vehicle, and then be deployed in space.

Performance Investigation of a Concentrated Solar Dish for Heating Applications

Abstract: Concentrated collectors offer a broad variety of solar energy uses, including heating, cooling, power production, and water desalination. This study was conducted to construct and test a concentrated parabolic solar dish water heater. The aperture size of the dish is 4.556m2 , and a copper absorber has a surface area of 0.2278m2 , a volume of 0.015m3 , and a concentrating ratio of 20. The water is heated up to 120°C at a solar radiation intensity of 700W/m2 and a 20°C ambient temperature. The absorber's stagnation temperature reached 246°C in roughly 1500 seconds. The thermal efficiency of the system was found to be 46%.

Design and installation of (flower sun) a concentration dish and study its parameters

Abstract: Design and installation of (3m) aperture concentration, by using Six curved pieces in the form of parabola Was covered by Aluminum golden mirror, the (focus) at (1.52 m) from the center of parabolic dish, a receiver (boiler) fixed at focus, the concentration ratio (37), we find the heat loss (29.780 W), and the useful energy (1376.93W) and the efficiency of the concentration 60 % at (500-750W/ ) the solar dish suitable for solar application.

Research on accurate non-contact temperature measurement method for telescope mirror

Abstract: Non-contact temperature measurement for a solar telescope mirror is critical for improving the mirror seeing and thermal deformation of solar telescopes, a long-standing challenge in astronomy. This challenge arises from the telescope mirror's inherent weak thermal radiation, often overwhelmed by reflected background radiations due to its high reflectivity. In this work, an infrared mirror thermometer (IMT) is equipped with a thermally-modulated reflector, and a measurement method based on an equation for extracting mirror radiation (EEMR) has been developed for probing the accurate radiation and temperature of the telescope mirror. Using this approach, we can extract the mirror radiation from the instrumental background radiation via the EEMR. This reflector has been designed to amplify the mirror radiation signal incident on the infrared sensor of IMT, while inhibiting the radiation noise from the ambient environment. In addition, we also propose a set of evaluation methods for IMT performance based on EEMR. The results reveal that the temperature measurement accuracy of IMT to the solar telescope mirror using this measurement method can be achieved better than ±0.15°C.

Design of a new static solar concentrator with a high concentration ratio and a large acceptance angle based on bifacial solar cells

Abstract: Solar concentrators are used in solar photovoltaic systems to lower the cost of producing electricity. In this situation, fewer solar cells can be used, lowering the overall cost of the system. The purpose of this article is to design, construct, install and test a stationary (non-tracking) concentrating system in Irbid, Jordan. Bifacial solar cells are used in the design. Two concentrator designs (with the same concentration ratio) are experimentally tested. Conc-A has a parabolic shape in the lower part but flat reflecting walls, whereas Conc-B has a standard compound parabolic shape in all parts. The receiving solar cells are arranged in three distinct positions in each concentrator. The results reveal that the output power from both concentrators is affected by the placement of the receiving solar cells within the concentrator. It has also been found that concentrators with flat reflecting walls perform better than those with parabolic reflecting walls. Conc-A’s power collection is ~198% greater than that of a non-concentrating device. When Conc-B is used, the increase in power is ~181%.

Fundamental study on optical performance of low-melting-point metal mirrors for space telescopes

Abstract: The installation of telescopes with larger primary mirrors in outer space is required for the study of the early universe. However, the shipping, assembling and maintenance of the primary mirror are technical challenges. The primary mirror made of low-melting-point metal (LMPM) enables to simplify these procedures. The rotating liquid metal surface is shaped into a parabola and solidified on the site. The technological feasibility depends on the dynamic transformation of the parabolic LMPM mirror and its optical reflectance. The dynamic transformation of LMPM mirror was clarified by means of experiments with liquid gallium (Ga), which has a melting point of 302.91 K. The parabolic shape of solid Ga mirror was produced by the axial rotation and the solidification. The parabolic shape agreed with the theoretical curve based on physical model. The reflectance spectra on the surface of various LMPMs solidified (i.e., Ga, lead (Pb), tin (Sn), bismuth (Bi), lead-bismuth eutectic (Pb-Bi) and Wood’s metal (Bi-Pb-Sn-Cd)) were measured. The reflectance of Ga solidified was approximately 70 % and was not degraded in the near-infrared wavelength due to the favorable optical characteristics. The reflectance both for p-polarized and s-polarized light of Ga solidified was measured by the spectrophotometer with the polarizer at the angle of incidence of 30°, 45°, 60° and 75°. The trend of measured reflectance agreed with theoretical prediction.

Experimental Investigation of Solar Cooker Using Parabolic Dish Collector for Indoor Cooking Application

Abstract: Traditional cooking methods are one source of greenhouse gas emissions. Researchers are actively exploring a solution to replace this conventional cooking process with renewable and sustainable means. Among the different renewable energy sources, solar energy is a promising option. Solar cookers are devices that utilize the thermal energy obtained from the sun to cook, boil, fry, or roast foods either directly or indirectly. In this study, a solar cooker based on a parabolic dish solar concentrator was designed, manufactured, and tested by using Shell Thermia Oil B as a heat transfer fluid. The aperture area of the parabolic dish solar concentrator used was 1.4 m2. A series of stagnation and water heating tests were conducted repeatedly, and the average value of the test parameters was recorded to check the performance of the developed solar cooker. As per the water heating test, the solar cooker’s average interval and standardized cooking power were found to be 113.89 W and 131.17 W, respectively. From the stagnation test, the maximum temperature obtained inside the cooking pot was 134 °C. Furthermore, the overall energy efficiency and exergy efficiency of the solar cooker have been found to be 10.3% and 0.18%, respectively. The solar cooker was able to cook 0.5 kg of rice with 1 L of water in 120 minutes. In general, from the study, it can be concluded that the developed indoor solar cooker with Shell Thermia Oil B as a heat transfer fluid shows a promising result.

Heat transfer fluids in parabolic trough collector (PTC) : A review study

Abstract: A solar thermal collector is a heat collector that absorbs heat via sunlight. It is a device that turns the thermal energy in sunshine or solar radiation into a useful and storable form. This energy is conveyed via electromagnetic radiation with wavelengths ranging from infrared (long) to ultraviolet (short). Solar energy is one of the cleanest and most versatile renewable energy sources when compared to other renewable energy sources. Solar trough collectors (PTC), Compound Parabolic Collectors (CPC), Linear Fresnel Collectors (LFC), Solar Towers, and Solar Dish Collectors are all types of solar concentrator systems. One of the most common types of solar concentrators is the parabolic trough collector (PTC). Working fluids, also known as heat transfer fluids (HTFs), are a crucial component of (PTC) that will be investigated. Water, thermal oil, molten salts, and gases are just a few of the working fluids used in the parabolic trough collector, all of which types operate in a temperature range. This research evaluates thermal performance of a parabolic trough collector by employing different heat transfer fluids (HTFs) at a temperature range up to 823 K under various operating conditions. The fundamental physical parameters, such as specific heat, density, viscosity, and thermal conductivity of working fluids (HTFs) and their output temperatures, thermal efficiency, advantages, disadvantages, and cost of the working fluids are also presented. After comparing the various working fluids which are used in parabolic trough collectors (PTC), it is found that Liquid Sodium is the most reliable heat transfer fluid (HTF) based on number of factors, including useful energy, thermal efficiency, low cost, high temperature operation range, and physical qualities in operation. Liquid sodium provides good thermal performance factors, including useful energy, thermal efficiency, low cost, and a high temperature operation range.

Design, Construction, and Control Tracking of Solar Thermal Concentrator by Using PLC in Erbil

Abstract: This paper demonstrates the construction designing analysis and control strategies for fully tracking concentrated solar thermal by using programmable logic control in the city of Erbil-Iraq. This work used the parabolic dish as a concentrated solar thermal. At the focal point, the collected form of energy is used for heating a (water) in the receiver, analyzing this prototype in real-time with two different shapes of the receiver and comparing the results. For tracking the parabolic dish, four light-dependent resistors are used to detect the sun's position in the sky so that the tracking system follows it to make the beam radiation perpendicular to the collector surface all of the time during the day for maximum solar power energy. This work discusses the essential stages of a two-axis prototype; implementation, solar-location strategy, the analysis in terms of theory, structural design, and material. For two-axis-prototype is implemented with the help of programmable logic control -Siemens (S7-1200) as a control unit. This study results show that a parabolic dish tracker with a cylindrical conical receiver obtains 15.25% Improved efficiency in comparison to the cylindrical receiver. According to the testing results of the prototype design, both shapes of the receiver are convenient for steam production.

Evaluation of Energy Production using Parabolic-Dish Solar Collector: A Case Study of Iraq

Abstract: The parabolic dish reflector solar collector is one of the significant and most efficient steam-producing solar concentrating systems in thermoelectric power plants and, furthermore, it's considered to be environmentally friendly (renewable energy). Iraq has vast land for installing solar collectors to generate steam and use for thermal power plants. However, no such application/power plant has yet been built. Therefore, the proposed study investigates opportunities for using PDR solar collectors, including all advantages and challenges. To implement and estimate the productivity and efficiency of the PDR in (Diyala City / Iraq), a PDR solar collector with a total area of 0.708 m2 (including the glass pieces used as a reflective surface) was designed and fabricated. These glass pieces have been utilized to increase the reflection of solar rays by 80% when compared to a traditional case/setup. Two different systems (open and closed) were considered to investigate the performance of thermal power . The results show that the absorption temperature was increased from 34.6 to 95 °C. On the other hand, the coefficient of heat loss by convection increases by about (795.5 W). In addition, it was pointed out that the coefficient of total heat loss over time was increased by about 25 to 41% (closed and open systems). Furthermore, the experimental findings clearly demonstrate the usefulness of PDR solar heaters in Iraq. Hence, its confidently believed that this research will be useful in the future for this type of thermal power plant.

Solar-pumped fiber laser using a solid-state luminescent solar collector

Abstract: We have developed a fully planar solar-pumped fiber laser using a solid-state luminescent solar collector (LSC). This laser does not use any focusing device, such as a lens or mirror; thus, it can lase without tracking the sun. Our developed device with an aperture of 30 cm emits 15 mW, corresponding to an optical-to-optical conversion efficiency of 0.023% and a collection efficiency of 0.21 W/m2. A 12-fold improvement over a previously developed liquid LSC is achieved by combining the total internal reflection of the solid-state LSC with dielectric multilayer mirrors. The observed laser power is in good agreement with that predicted via numerical simulation, demonstrating the effectiveness of our proposed method.

Tight-focusing parabolic reflector schemes for petawatt lasers.

Abstract: A comparative study of three different tight-focusing schemes for high-power lasers is performed numerically. Using the Stratton-Chu formulation, the electromagnetic field in the vicinity of the focus is evaluated for a short-pulse laser beam incident upon an on-axis high numerical aperture parabola (HNAP), an off-axis parabola (OAP), and a transmission parabola (TP). Linearly- and radially-polarized incident beams are considered. It is demonstrated that while all the focusing configurations yield intensities above 1023 W/cm2 for a 1 PW incident beam, the nature of the focused field can be drastically modified. In particular, it is shown that the TP, with its focal point behind the parabola, actually converts an incoming linearly-polarized beam into an m = 2 vector beam. The strengths and weaknesses of each configuration are discussed in the context of future laser-matter interaction experiments. Finally, a generalization of NA calculations up to 4π-illumination is proposed through the solid angle formulation, providing a universal way to compare light cones from any kind of optics.

Geometric analysis and optimization of a parabolic concentrator for production at both thermal receivers at its focal point

Abstract: The exploitation of solar energy for the production of electricity through a thermodynamic cycle is done according to several methods. The parabolic concentration method remains the best because of its high thermal efficiency (about 68%) but the least used because of difficulties related to the storage of its energy. Our work concerns a parabolic reflector with two receivers at its focal point. These two receivers are a boiler and a Stirling engine. The boiler and the Stirling engine receive the energy concentrated by the reflector. In the presence of the Sun it is the Stirling engine that produces the electricity. During the periods when the solar energy is insufficient or absent it is the thermal tank that will send the heat to the fluid that will turn the blades of a turbine to produce electricity. To meet the thermal needs of these two receivers, the efficiency of the reflector's heat production must be improved. To this end, we have studied the possibilities of optimizing the geometric parameters of the parabolic concentrator. For a surface of 12.56 m2 of the reflector, the use of standard geometric parameters allowed us to obtain a daily energy of 824.474 kWh when the solar power is 1104.938 kWh. For the same surface, using the optimized parameters, the production increased to 975.937kWh; a gain of 13.7%. This study allowed us to discover that the geometric and optical parameters strongly influence the thermal production of a reflector.