Parabolic Reflector Research Articles

Preliminary analysis of a parabolic trough concentrating solar power system integrated with radiative cooling

Abstract Parabolic trough concentrating (PTC) solar power generation is the most technologically mature way of concentrating solar power technology. PTC plants are generally located in flat desert areas, with sufficient sunshine but lacking water for condenser cooling. Herein, a novel cooling system, radiative cooling (RC) integrated with a parabolic trough reflector, is proposed for the PTC system, which means that the waste heat generated during power generation can be radiated to the colder universe by the parabolic reflectors instead of being entirely dissipated to ambient air without water evaporation or land occupation. The simulation results demonstrate the potential of the proposed cooling system to serve as an independent cooling system by adjusting the temperature difference between radiator and ambient within −4.1 to 9.3°C, with 100% water savings and a water pump power consumption rate of 1.8–2.1%. The capital cost of implementing this new cooling system is estimated to be $27.4–54.5/kWe. Furthermore, an annual average of 86.1% of total cooling capacity is dissipated through thermal radiation, with 14.4% directly sent to the cold universe through the atmosphere window, providing a possible method to solve the water problem of power plants in torrid-arid areas and curb global warming if large-scale applications are used.

Review of Concentrated Solar Power Technology Applications in Photocatalytic Water Purification and Energy Conversion: Overview, Challenges and Future Directions

Photocatalysis, a promising semiconductor-based technology activated by free and eternal solar energy, has great potential for addressing environmental remediation and energy conversion challenges. Concentrated solar power (CSP) technologies, namely parabolic trough reflectors, solar power towers, parabolic dish reflectors and linear Fresnel reflectors, exhibited excellent feasibility for boosting solar-driven photocatalytic processes. Based on the structural characteristics of CSP technologies, the CSP-based photocatalytic reactors could be divided into concentrated types and non/low-concentrated types. This academic review comprehensively investigated the integration of CSP technology in photocatalysis, emphasizing the feasibility of sunlight as an ideal energy source. Additionally, considering the optimal light irradiance and reaction temperature demands for achieving efficient photocatalytic processes, the significance of introducing CSP into solar light-driven photocatalytic reactions was highlighted. Moreover, the current challenges that exist in CSP-based photoreactors were identified, and potential solutions were proposed accordingly. This work hopes to provide some references for the future study of CSP-based photocatalytic reactors under the theme of sustainable development.

Paper Certificate An efficient parabolic dish engine based on Rankine cycle

In this research work, a case study carried out to evaluate the technical viability of a parabolic dish based concentrator to convert solar energy into electric power by means of a high performance Rankine cycle operating with, ethane, ammonia or water. The comparison of such cycles in terms of thermal efficiency and net developed work is the aim of the proposed research. The achieved results show that Stirling engine efficiency is so far lower than that of the Rankine cycle under the same operating temperatures since typical temperatures range from 650 °C to 800 °C resulting in Stirling engine conversion efficiencies of around 30 % to 40 %, while the proposed Rankine cycles can surpass such mark.

Pressurized concentrated solar power receiver designed to operate with closed Brayton cycles

Parabolic through and parabolic dish concentrators (PDC) followed by a volumetric receiver is proposed, studying the performance behavior of a closed Brayton cycle (CBC) operating with He and N2. A pressurized gas (helium, nitrogen) circulates along the volumetric receiver capturing the concentrated thermal solar energy which is converted into mechanical energy by a CBC. The overall efficiency of the plant (PC-Receiver + CBC) is being computed under variable parameters to determine the operating conditions for which efficiency is acceptable. As consequence of the proposed analysis, it is concluded that direct coupling between volumetric receiver and thermal engine renders high efficiency while avoiding a heat exchanger.

Sustainable and clean water distillation by parabolic dish collector and different heat absorber and thermal storage materials: An experimental study

In this study, an integrated solar distillation unit with a parabolic dish collector and a spherical solar water distillation unit is designed. The use of parabolic dish collector increases the evaporation rate of the saltwater in the lower chamber (basin) of the spherical distillation unit considerably. The performance of solar water distillation system is investigated for different types of basin material, including copper, zinc, and iron. In the second part, the gravel is used in the copper basin of solar distillation system as the thermal energy storage material. The thermal efficiency, water productivity, exergy efficiency, and freshwater production cost of the integrated solar distillation system with different types of basin materials are studied. The thermal efficiency of the integrated solar distillation system with the copper, zinc, and iron basins was 13.97 %, 10.72 %, and 9.88 %%, respectively. The water productivity of the integrated solar distillation system with copper, zinc, and iron basins was 2.592 kg, 2.27 kg, and 1.825 kg, respectively during 9 h of experiment. The exergy efficiency of the integrated solar distillation system with the copper basin was better than the zinc and iron basins. The gravel can increase the productivity of solar distillation system up to three times in the sunset and night hours.

Design of a Deployable Broadband Mesh Reflector Antenna for a SIGINT Satellite System Considering Surface Shape Deformation.

In this paper, we propose a deployable broadband mesh reflector antenna for use in signals intelligence (SIGINT) satellite systems, considering performance degradation due to shape deformation. To maximize gain by increasing the diameter of the reflector while reducing the weight of the antenna, the reflector of the antenna is designed using lightweight silver-coated Teflon mesh. The mesh reflectors are typically expanded by tension to maintain their parabolic structure; thus, shape deformation cannot be avoided. This shape deformation results in shape differences between the surface of the mesh reflector and the ideal parabolic reflector, thus resulting in the degradation of the performance of the mesh reflector antenna. To observe this degradation, we analyze antenna performance according to the number of arms, the number of joints, the feed distance, and the distance from the reflector center to each joint. The performance of the mesh reflector antenna is examined using an effective lossy conducting surface (ELCS) that has the same reflectivity as the silver-coated Teflon mesh to reduce simulation time and computing resources. The designed silver-coated Teflon mesh reflector and the double-ridged feed antenna are fabricated, and the bore-sight gain is measured using the three-antenna method. The measured bore-sight gain of the proposed antenna is 31.6 dBi at 10 GHz, and the measured and simulated results show an average difference of 3.28 dB from 2 GHz to 18 GHz. The proposed deployable mesh reflector antenna can be used in a variety of applications where small stowed volume is required for mobility, such as mobile high-gain antennas as well as satellite antenna systems. Through this study, we demonstrate that shape deformation of the mesh reflector surface significantly affects the performance of reflector antennas.

A Study for a Radio Telescope in Indonesia: Parabolic Design, Simulation of a Horn Antenna, and Radio Frequency Survey in Frequency of 0.045–18 GHz

After years of preparation, the Indonesia National Observatory, located in Mount Timau, Kupang Regency, is currently in the completion stage of research in astronomy and astrophysics and related subjects. An optic telescope with a 3.8 m diameter is expected to receive its first light in mid-2024. A feasibility study for Indonesia’s radio telescopes and networks is in progress. A single-dish parabolic radio antenna with a diameter of 20 m is proposed to work in a frequency range of 1–50 GHz. An array dipole antenna with an area of 100 m × 100 m will also be installed at a 70–350 MHz frequency. A feasibility study about system design is in progress, and a radio frequency interference (RFI) survey has been underway since 2014. In this paper, we described the design of radio telescopes such as parabolic reflectors, horn antenna, and the radio frequency interference (RFI) in the surrounding area of the National Observatory, covering the frequency band from 45 MHz to 18 GHz. The frequencies in 45–85 MHz and 120–360 MHz intervals are still relatively quiet and suitable for developing radio telescopes. The selected higher frequency of 1.4 GHz for a neutral hydrogen (HI) spectral line, 6.6 GHz for a methanol (CH3OH) spectral line, and 8.6 GHz for a helium (3 He+) spectral line is still relatively quiet and suitable for the development of radio telescopes.

Experimental comparison of a DC PV cooker and a parabolic dish solar cooker under variable solar radiation conditions

Solar cookersare not all-weather cooking devices and operate poorly during cloudy and low sunshine conditions. Their performance is evaluated usually during high solar radiation conditions. The objective of this study is to compare two solar cookers under variable non-ideal weather conditions. The comparison is carried out under variable solar radiation conditions to compare the all-weather performance of these two cookers. This is a major novelty compared to previous work reported where solar cookers are tested under high and ideal solar radiation conditions. Experiments to compare a PV DC battery-powered solar cooker and a parabolic dish solar cooker are presented in this paper. A total of six water heating tests are carried out to comprehensively compare these two types of solar cookers under different solar radiation conditions. Also, four food cooking tests are carried out with different types of food. The PV solar cooker shows almost constant input electrical power in the range of 160–180 W during the experimental tests whereas the input thermal power for the parabolic dish is highly variable depending on the solar radiation conditions (200–1200 W). The output water heating powers obtained using the PV cooker (66–100 W) are comparable to those obtained with parabolic dish solar cookers (78–142 W), regardless of the significantly lower input heating power. Water is boiled in all the heating tests with the PV cooker, whereas water is boiled for tests with low solar radiation variability for the parabolic dish solar cooker. Higher water heating efficiencies within a small range (0.38–0.57) are obtained for the PV cooker compared to the parabolic dish solar cooker (0.11–0.42). The water heating efficiency of the parabolic dish solar cooker is highly affected by ambient solar radiation and windspeed conditions. Food was well cooked with the PV cooker in all four food cooking tests, whereas food in only two tests with low solar radiation variability was well cooked for the parabolic dish solar cooker. The PV cooker proves to be an all-weather cooker from the experimental results obtained. Future work will extend the use of the PV system for other domestic applications such as lighting and refrigeration together with solar cooking for a multipurpose DC decentralized system for communities without grid connectivity.

Ray Tracing and Simulation of Parabolic Dish Collectorusing Soltrace for Vehicle Applications

Concentrated solar power has the potential to produce large-scale renewable energy sources. Concentrated solar energy is produced using mirrors, reflective materials, or lenses on conical surfaces such as a parabolic dishes, parabolic troughs, towers, Fresnel reflector systems, and dish sterling collectors. The concentrated light source was converted into heat energy, which drove the heat engine into an electrical power generator. To gain more heat energy, the solar rays must be trapped and concentrated on their conical focus points. To increase the net overall efficiency of the system, it is vital to know the optical performances of the subsystem formed by the solar receiver and the parabolic concentrator. In this study, a beam of incident solar rays was traced on a parabolic dish collector, and a simulation is performed for concentrator behaviour using the ray-tracing code SolTrace developed by the NREL laboratory. For an incident radiation of 1000 W/m2 (considering 10000 photon rays), their optical performance and solar heat flux were simulated. The results show that the number of elements in SolTrace varies depending on the CFD mesh density, the number of rays utilised in the Monte Carlo technique and their impact on generating a resolution-independent solution. Investigating the ray tracing of the disc concentrator, the propulsive energy for viable applications can be analysed.

Self-Test of Air-Coupled Probe for Sensitivity Map Production Using Parabolic Reflector.

The spatial distribution of a transduction efficiency over the air-coupled probe surface was proposed as a convenient tool for the probe integrity inspection. In this research, a parabolic reflector is used for passive focusing of the acoustic wave on the surface of inspected probe. Therefore, no additional transducer is required for inspection: probe is used for self-inspection. This approach allows to avoid the expensive focused transducer and replaces it by the same-type air-coupled transducers as probe under test. Moreover, the use of the parabolic mirror for focusing is frequency-independent; therefore, such approach allows to inspect a wide range of the probes. Spread spectrum signals were used for excitation to improve the SNR and bandwidth coverage. The results of the experimental measurements of air-coupled transducer sensitivity map with natural and artificial defects implemented have been presented. Comparison with previously proposed techniques is given. It was found that defects presence distorts the focused beam, creating large sidelobes. Therefore, sensitivity map obtained with the proposed technique is lower quality than with previously proposed techniques. Beam profile measurements using a miniature microphone have been presented. Aperture-limiting mask has been proposed to reduce the sidelobes arising due to defects presence and resulting measurements quality has been improved.

Testing solar cookers for cooking efficiency

Solar Cookers International (SCI) staff developed and implemented a calculation to measure the cooking efficiency of solar thermal cookers. The calculation complements and enhances SCI's existing performance evaluation process (PEP), which can now be used for determining both the standard cooking power and the cooking efficiency for solar thermal cookers. The standard cooking power value is a single measure of solar cooker performance taken when the temperature of the test water load is specifically 50 °C greater than ambient temperature. Cooking efficiency values extend the perspective of solar cooker performance, as they are applicable to a continuum of load temperature measurements made during a heating cycle. Cooking efficiency is the ratio of energy absorbed by the solar cooking load divided by the input solar energy intercepted by the device during a test interval. Examples of cooking efficiency calculations using water loads during three days of testing for an anonymous group of different types of solar cookers are: solar box oven (18.9 %), reflective-panel solar cooker (28.5 %), parabolic reflector (35.2 %), and evacuated-tube solar cooker (34.6 %).

Optoelectronic methane sensor based on two-color led module

The article proposes an optoelectronic two-wave method for monitoring the methane content in the atmosphere. Spectral characteristics are given two-color LED module LED39, LED32, photodiode PD36 and methane absorption spectrum. An optoelectronic sensor for monitoring the methane content in the atmosphere with high measurement accuracy has been developed, and its block diagram is shown. In an optoelectronic sensor for monitoring methane content in the atmosphere A two-color LED module with emission spectra of 3.2 microns (reference) and LEDs with emission spectra of 3.4 microns (working) were used . To increase the optical power of LEDs (3.2 and 3.4 microns), a design with more efficient heat removal and a parabolic reflector design for LEDs, which focuses IR radiation at an angle of 8-10 degrees, have been proposed. LED crystals with emission spectra of 3.2 microns and 3.4 microns are mounted in one housing to ensure high accuracy and sensitivity of the device.

Optimization of the Physical Aperture of the Parabolic Reflector Antenna

Optimization of the Physical Aperture of the Parabolic Reflector Antenna

Meteorological Research Enabled by Rapid-Scan Radar Technology

Abstract The scientific community has long acknowledged the importance of high-temporal-resolution radar observations to advance science research and improve high-impact weather prediction. Development of innovative rapid-scan radar technologies over the past two decades has enabled radar volume scans of 10–60 s compared to 3–5 min with traditional parabolic dish research radars and the WSR-88D radar network. This review examines the impact of rapid-scan radar technology, defined as radars collecting volume scans in 1 min or less, on atmospheric science research spanning different subdisciplines and evaluates the strengths and weaknesses of the use of rapid-scan radars. In particular, a significant body of literature has accumulated for tornado and severe thunderstorm research and forecasting applications, in addition to a growing number of studies of convection. Convection research has benefited substantially from more synchronous vertical views, but could benefit more substantially by leveraging multi-Doppler wind retrievals and complementary in situ and remote sensors. In addition, several years of forecast evaluation studies are synthesized from radar testbed experiments, and the benefits of assimilating rapid-scan radar observations are analyzed. Although the current body of literature reflects the considerable utility of rapid-scan radars to science research, a weakness is that limited advancements in understanding of the physical mechanisms behind observed features have been enabled. There is considerable opportunity to bridge the gap in physical understanding with the current technology using coordinated efforts to include rapid-scan radars in field campaigns and expanding the breadth of meteorological phenomena studied. Significance Statement Recently developed rapid-scan radar technologies, capable of collecting volumetric (i.e., three-dimensional) measurements in 10–60 s, have improved temporal sampling of weather phenomena. This review examines the impact of these radar observations from the past two decades on science research and emerging operational capabilities. Substantial breadth and impact of research is evident for tornado research and forecasting applications, in addition to documentation of other rapidly evolving phenomena associated with deep convection, such as tornadoes, hail, lightning, and tropical cyclones. This review identifies the strengths and weaknesses of how these radars have been used in scientific research to inform future studies, emerging from the increasing availability and capability of rapid-scan radars. In addition, this review synthesizes research that can benefit future operational radar decisions.

Experimental investigation and energy-exergy analysis of indirect liquid jaggery-making system based on parabolic dish concentrator

Experimental investigation and energy-exergy analysis of indirect liquid jaggery-making system based on parabolic dish concentrator

Experimental investigation and energy-exergy analysis of indirect liquid jaggery-making system based on parabolic dish concentrator

Experimental investigation and energy-exergy analysis of indirect liquid jaggery-making system based on parabolic dish concentrator

Numerical investigation of heat transfer in spirally coiled corrugated pipes: Assessment of turbulence models

The Archimedean spiral coil made of a transversely corrugated pipe represents the radiant heat absorber of a parabolic dish solar concentrator. The main advantage of the considered design is the coupling of two passive methods for heat transfer enhancement: coiling the flow channel and changing the surface roughness. The aim of this numerical study is to assess the capability of RANS models of different complexity (realizable k-?, SST k-?, and RSM linear pressure-strain) to adequately represent the heat transfer phenomena in the considered complex flow geometry for wide ranges of Reynolds and Prandtl numbers. The obtained results indicate that the realizable k-? model with enhanced wall treatment is inadequate to simulate the heat transfer for all flow conditions, while both SST and RSM slightly overestimate experimental data in the turbulent region and are able to predict laminarisation at low Reynolds numbers. The SST model predictions are more accurate in the transitional and at the beginning of the turbulent region, irrespective of the curvature ratio. The RSM predictions are generally more accurate in the turbulent region. Numerically obtained circumferential distributions of local Nusselt number reveal that considered turbulence models are unable to completely anticipate the interactions between the complex flow in the basic section of the pipe and the vortex flow within the corrugations.

Review of various solar cavity receivers of parabolic dish concentrators with design aspects and heat loss analysis

Review of various solar cavity receivers of parabolic dish concentrators with design aspects and heat loss analysis

Numerical investigation to optimize the modified cavity receiver for enhancement of thermal performance of solar parabolic dish collector system

The concentrated parabolic dish collector (PDC) systems are widely utilized for the purpose of generating high-temperature heat by receiving and converting solar energy efficiently into thermal energy. Cavity receivers including spiral coils have a common use in PDC system for optimal thermal performance. Therefore, to enhance the thermal performance of a PDC system, the present study investigates different cavity receiver configurations, such as cylinder and conical shaped receivers with flat and spherical absorber surface as well as the effect of spiral coil arrangement. To identify the most optimal spirally coiled cavity receiver, the comparison is conducted based on outlet temperature, heat exchange rate, thermal efficiency, effectiveness, and thermal performance capability (TPC). The investigations were conducted using the ANSYS Fluent CFD simulation software package. The SolTrace software package was utilized to compute the maximum heat flux incident on the absorber surface of the receiver, and peak heat flux data was used as input parameter at the absorber surface of the receiver. Furthermore, to select the suitable working fluid in PDC system, different heat transfer fluids, such as Syltherm 800, Xceltherm 600, ParathermHR™ and water, respectively were studied. From the thermal analysis of various proposed receiver geometries, the receiver with conical shape and spherical absorber surface is more efficient over other configurations. It provides 50 % higher heat transfer rate thancylindrical receiver with flat absorber surface. Moreover, receiver's thermal performance could modestly be improved by modifying the spiral coil pitch (variable pitch). In terms of pumping power consumption, readily availability, low viscosity, and high specific heat, water is suggested as working fluid for receiver of PDC system.

Optical and thermal investigation of hyperbolic cavity receiver with secondary reflector for solar parabolic dish collector

A hyperbolic-shaped cavity-type receiver with a second stage reflection for a 40 m2 solar parabolic dish concentrator (PDC) is presented in this paper,along with optical and thermal modeling. The receiver geometry and the secondary reflector complete the hyperbolic geometrical shape of the present receiver. This study aims to estimate heat losses owing to natural convection and radiation under influential parameters associated with solar parabolic dish system. Optical modeling has been performed with verified model using ASAP® 2013 V1R1. The optical simulations have been carried out for varying receiver height (h1), height of the secondary (h2) and diameter-to-total height ratios (d/h) of 0.5, 1, and 1.5 while keeping the diameter of the plane aperture of the receiver (d) constant. The optimum receiver geometry has been selected based on the performance in terms of optical efficiency. The maximum efficiency found is 91.72% for h1 = 0.75 m and d/h = 0.5 for the mounting distance of 4.21 m. The optimized shape is further studied to determine how the receiver absorptivity and the secondary reflector's reflectivity affect the optical performance. The absorptivity and reflectivity range from 0.86 to 0.94. Obtained optimum receiver geometry from the optical investigation is further analyzed to estimate the heat transfer rate. The thermal modeling is performed for 0°, 30°, 60°, and 90° orientations of the receiver in ANSYS Fluent 2020 R1. A comprehensive comparison among the available models has been reported and validated with well-established experimental data. This work has developed free convective Nusselt number correlation. It can be a valuable addition to the existing literature.