Fresnel Concentrator Research Articles

Bionically inspired flattened linear Fresnel concentrator and its photothermal application on building façade

The paper presents a low wind-load linear Fresnel concentrator (LFR) for solar energy harvesting on high-rise building façades. This concentrator, characterized by a significantly reduced thickness compared to conventional designs, is termed “flattened linear Fresnel concentrator.” The concentrator imitates the “Shade Avoidance Response” of plants by attaching a rod to the mirror to form an Off-axis mirror that mitigates inter-mirror blocking in a constrained space. The paper initially outlines a comprehensive overview of the bionic theory of the concentrator. Subsequently, the paper develops an optimization model and parameter calculation procedure for the two competing objectives of flattening profile and boosting optical efficiency. Based on this, the paper discusses in detail the advantages of flattened Off-axis concentrators for building facades. Finally, this paper conducted a photothermal comparison experiment with a conventional LFR device installed vertically, and by analyzing the experimental data, it was revealed that the photothermal efficiency of the Off-axis flattened concentrator was 10.82% higher than that of the conventional LFR device, and the photothermal efficiency in one day reached 57.43%. Additionally, the paper examines the sunlight self-adaptive feature of the flattened Off-axis concentrator, demonstrating its advantages for façade integration through experimental data analysis.

Design and Preliminary experiment of an Off-axis aequilate-mirrors linear Fresnel concentrator with sunlight self-adaptive feature

The Off-Axis Linear Fresnel Reflector (LFR) is an innovative, compact solar concentrator designed to reduce device height and wind-load without compromising efficiency. It is crucial in applying LFR devices to applications such as building façades. To this aim, The Off-axis LFR design is introduced to addressing the inter-mirror blocking issue that diminishes the efficiency of conventional LFRs. Initially, an optimized Aequilate-mirrors design was proposed to reduce manufacturing complexity and cost. Subsequently, a crank-slider mechanism was introduced as a solution to the issue of inconsistent angle adjustment among the mirrors. Additionally, the paper details the sunlight self-adaptive feature of the Off-axis LFR concentrator, where the LFR mirrors can independently rotate to track the sun’s position, adaptively altering the mirror array’s profile and sunward aperture. This feature maximizes the device’s sunlight harvesting capacity, particularly in angled sunlight conditions. A prototype of the Off-axis LFR device was designed and built for assessment, featuring a focus length of just 78 mm and an overall 145 mm housing height. The paper then discusses how the sunlight self-adaptive features enhance the efficiency during the early morning and twilight hours. Comprehensive testing, including mechanical driving, laser focusing, and outdoor full-function verification, was conducted. Ultimately, comparative photo-thermal efficiency tests with a similarly sized conventional LFR concentrator demonstrated that the Off-axis LFR concentrator could achieve a significant increase in efficiency, with an all-day average thermal efficiency improvement of over 10 %. Based on the previous theoretical study, this study has completed the engineering prototype design and validation. And confirmed a thermal concentration efficiency of 44.36 % within a height of 145 mm in experiments.

Geometrical Aspects of the Optics of Linear Fresnel Concentrators: A Review

Linear Fresnel concentrators (LFR) are widely seen by the scientific community as one of the most promising systems for the production of solar energy via thermal plants or concentrated photovoltaics. The produced energy depends on the optical efficiency of the LFR, which is mainly dictated by the geometry of the plant. For this reason, the analysis of LFR geometry and its effects on optical behavior is a crucial step in the design and optimization of a Fresnel plant. The theoretical and computational tools used to model the optics of a LFR are fundamental in research on energy production. In this review, geometrical aspects of the optics of linear Fresnel concentrators are presented, with a detailed discussion of the parameters required to define the geometry of a plant and of the main optical concepts. After an overview of the literature on the subject, the main part of the review is dedicated to summarising useful formulas and outlining general procedures for optical simulations. These include (i) a ray-tracing procedure to simulate a mirror field, and (ii) a fast quasi-analytical method useful for optimizations and on-the-fly computations.

Exergetic and environment assessment of linear fresnel concentrating photovoltaic systems integrated with a porous-wall mini-channel heat sink: Outdoor experimental tests

The photovoltaic heat sink integrated systems can effectively control the temperature of solar cells and increase output power. The linear Fresnel concentrator photovoltaic heat sink integrated systems (LFC-PV systems) consists of a solar cell, a porous-wall mini-channel heat sink (MFP-channel) and a linear Fresnel concentrator (LFC) mirror array. Cooling fluid R141b absorbs heat from solar cell back by flow boiling heat transfer. In this work, we tested the system performance outdoors and the collected experimental data were used for energy analysis, exergy analysis and environmental analysis to evaluate the advantages and disadvantages of the integrated system. The experimental data show that the heat dissipation of solar cells by using a porous-wall mini-channel heat sink can not only well control the surface temperature of solar cells between 35 °C and 40 °C, but also increase the output power and exergy, where the output power can reach a maximum of 10.73 W. Therefore, it is recommended to use a porous-wall mini-channel heat sink for the thermal management of the LFC photovoltaic system.

Development and Performance Evaluation of a Linear Fresnel Concentrator for Heating Water

Linear Fresnel Concentrator is a type of solar concentrator that uses a series of flat or slightly curved mirrors to focus sunlight onto a linear receiver tube. “The Development and Performance Evaluation of a Linear Fresnel Concentrator (LFC) for heating water was evaluated.” The LFC system utilizes locally sourced materials to develop the solar tracking system, automated control and a water heating system to optimize energy output. Performance evaluation results shows hourly readings of the ambient, absorber and reservoir temperatures which were recorded between 9:00 am and 04:00 pm but between the hours of 12:00 pm and 4.00 pm, hot water temperatures of above 50oC were achieved. Moreover, the maximum hot water temperature achieved was 96.69oC while the peak hot water temperature was 93.98oC and a thermal efficiency of 40.27%. Readings were taken for a period four days. Hence, the automated LFC system demonstrates the potential for cost-effective and sustainable water heating, particularly in regions with high solar irradiance.

Comprehensive performance analysis of CST-PV system based on spectral beam splitting film

Abstract In this paper, a novel linear Fresnel concentrator (LFC) with a rotating platform was constructed, and a novel concentrated solar thermal and photovoltaic (CST-PV) hybrid system utilizing spectral beam splitting was established on the LFC. A spectral beam-splitting film (SBSF) was coated on the PV cell’s inner glass wall, replacing the LFC’s primary reflector. The SBSF can transmit the solar spectrum of 300-1100 nm to the photovoltaic (PV) cells and reflect the remaining solar wavelengths to the absorber to generate heat. The LFC’s cosine efficiency and end efficiency after azimuthal compensation by a rotating platform were calculated through theoretical analysis. The effects of temperature on the efficiency of PV and linear Fresnel solar systems were studied through experimental and numerical simulations. The comprehensive utilization efficiency evaluation method was established. The results show that the LFC’s end efficiency and cosine efficiency in this paper, after azimuthal compensation, increased by 31.7% and 33.7%, respectively, compared with the east-west and north-south axis placement. The comprehensive utilization efficiency of the CST-PV system based on SBS is 61.58%, which increased by 13.47% compared to that of the single fixed PV system.

Performance analysis of a novel solar Linear Fresnel concentrator system based on spectral beam splitting

Photothermal and photovoltaic are the most common and commercialized ways of utilizing solar energy. However, they cannot use solar energy efficiently. SBS (spectral beam splitting) technology is an efficient solar energy utilization technology that can realize the full spectrum utilization of solar energy. The current work involved: (1) Proposing a SBS-LFCs (linear Fresnel concentrator system) based on spectral beam splitting. In this system, the SBS photovoltaic panel replaces the conventional linear Fresnel concentrator lens, which can realize photovoltaic and photothermal utilization at the same time; (2) Developing a spectral splitting thin films configuration using the Needle method whose transmittance is higher than 90% against 380 nm-1100 nm band range; (3) Designing the SBS photovoltaic panel structure. The cover glass surface is covered with a SBS thin film. The SBS photovoltaic panel replaces the concentrator lens of LFCs; (4) Taking four typical days as examples, the annual power generation of a SBS linear Fresnel focusing system was predicted. The outcome indicates that the total conversion efficiency of solar thermal power in the system is 23.8%, 23.5%, 23.5%, and 23.6% on the spring equinox, summer solstice, autumn equinox, and winter solstice, respectively. Compared to conventional monocrystalline silicon cells, the photoelectric conversion efficiency has been improved by 14.6%, 12.8%, 12.5%, and 14.1%, respectively.

Potential of Steam Generating by The PMMA Fresnel Lens Concentrator for Indoor Solar Cooker Application

Solar power is an alternative energy source that can be used for cooking. It is a simple, secure, and useful way to cook food without using conventional fuels that pollute the air. Solar cookers offer various benefits to the user’s health, productivity, and income as well as to the environment. Solar energy is abundant in a tropical country like Indonesia, making it a dependable and sustainable of energy resource. The study’s goal is to analyze the potency of steam produced by a solar cooker that uses a Fresnel lens concentrator. The thermal performance of the Fresnel lens concentrator with a conical receiver on the solar cooker prototype is discussed in this research. In the construction of solar cookers, PMMA (Polymethyl-Methacrylate) Fresnel lenses, manual trackers, and conical receiver types are used. The research conducts an experimental analysis of the thermal performance of the prototype solar cooker using a Fresnel lens concentrator with a conical receiver. This empirical approach provides valuable data on the efficiency and effectiveness of the solar cooker design. The experiment result shows the cumulative average solar irradiation, the average collection of solar energy per time of Fresnel lens concentrator, and the heat utilized of steam from conical receiver are 709.09 W/m², 456.14 Watt, and 383.88 Watt, respectively. The results of this study suggest that Fresnel lens concentrators are a promising development for indoor solar cookers and therefore provide a pathway for increased utilization of solar cooking technology.

Energy management of a concentrated photovoltaic−thermal unit utilizing nanofluid jet impingement in existence of thermoelectric module

To generate a concentrated photovoltaic–thermal (CPVT) unit system, linear Fresnel concentrators have been attached to a PV unit and a thermoelectric generator (TEG) has been combined in this work to boost productivity. In the presence of concentrators, the temperature of the silicon layer increases. While electrical output is enhanced for the CPVT unit, the non-uniform isotherms can decrease the lifetime of the panel, so confined jets of alumina–water nanofluid have been applied for cooling. To validate the numerical code, previous papers were examined and good accommodations were reported. Various values of the inlet temperature (T in) and velocity (V in) of jets have been analysed. The impacts of installing concentrators on overall performance and CO2 mitigation have been investigated. An increase in V in leads to an incremental increase in thermal performance of about 4.2% and thermal uniformity is enhanced by about 13.91%. The thermal power of the system is enhanced by about 2.19 times as a result of adding concentrators. Also, the PV power is enhanced by 86.22% in the presence of the reflectors. With the increase in T in, the thermal and electrical performance decrease by about 19.95% and 5.24%, respectively. Installing concentrators enhances the overall performance by about 6.55%. After 10 years, the amount of CO2 mitigation for the CPVT-TEG system reaches 148.28 ton.

Exergoeconomic and exergoenvironmental analyzes of a new biomass/solar-driven multigeneration energy system: An effort to maximum utilization of the waste heat of gasification process

In addition to improving the sustainability and thermodynamic efficiencies of an energy conversion system, a solar/biomass-driven integrated energy system can also reduce environmental impacts. The current work presents a detailed evaluation (thermodynamic simulation and exergoenvironmental and exergoeconomic analyzes) of a solar/biomass-powered multigeneration energy system (MGES). Accordingly, four units were considered for electric power generation. A linear Fresnel concentrator (LFC)-driven solar farm, a municipal solid waste (MSW) gasification cycle, an alkaline water electrolyzer (AWE) unit (to produce hydrogen gas), and a multi effect desalination (MED)-based Seawater desalination cycle are also considered in the MGES. A multi-objective optimization (regarding the technical, cost, and environmental objective functions) was also developed for the offered MGES. The proposed configuration for the MGES has a new components process that had not been reported in the publications. The power generation level was improved by utilizing the energy available in waste heat in the different downstream units. The offered MGES can generate 154.1 MW of electrical power, ∼ 280 kg per day of hydrogen gas, and 265.4 m3/h of fresh water. Meantime, the offered MGES can 38.8 % and 32.2 % efficient in terms of energy and exergy, respectively. Besides, the LCOE value and the environmental impacts index for the offered MGES were approximately 3.82 USD/GJ and 0.545 Pts/GJ, respectively. Also, raising the syngas temperature at the inlet of the combustion chamber can be a reasonable decision from the exergetic, economic and (especially) environmental standpoints.

The Potential of Steam Generating by The PMMA Fresnel Lens Concentrator for Indoor Solar Cooker Application

The Potential of Steam Generating by The PMMA Fresnel Lens Concentrator for Indoor Solar Cooker Application

Experimental and Numerical Evaluation of Solar Receiver Heat Losses of a Commercial 9 MWe Linear Fresnel Power Plant

Evaluating the heat losses of linear Fresnel concentrator (LFC) receivers is crucial for determining plant efficiency and managing the flow rate in solar lines. This becomes particularly significant when operating in direct steam generation to manage the steam quality at the line outlet. In general, the LFC receiver heat losses are determined experimentally on prototype systems to control the inlet condition or numerically using 3D computational fluid dynamics models or 1D mathematical models. The originality of this work is in reporting the study of heat losses of a commercial 9 MWe solar Fresnel power plant without impacting its electricity production. The experimentally measured receiver’s linear heat losses were found to be well represented by a second-degree polynomial function of the difference between the inlet/outlet fluid temperature average and the ambient temperature. Finally, to express the strong influence of wind speed on the receiver heat losses, a 1D single-phase model was developed and adapted to include the current receiver degradation. To conclude, the model was validated by comparing the experimental and theoretical results. Based on this comparison, it can be concluded that the model accurately predicts experimental heat losses with an acceptable uncertainty of ±30%, regardless of the wind velocity.

Ray tracing analysis of linear Fresnel concentrators and the effect of plant azimuth on their optical efficiency

Although for a quite small number of installations, Linear Fresnel Collectors (LFC) represent an interesting technology for efficient solar energy exploitation at medium to high temperatures thanks to their lowest land area per electric power ratio if compared to other available CSP solutions. The first prototypes were realized in the ‘60 by Professor Giovanni Francia at the University of Genova, Italy. In this research, 3D ray tracing simulations are performed employing the proprietary, literature-validated code FresnelSim. This in-house developed algorithm, which models the effect of shading, blocking and end effects based on the plant geometrical parameters, has been implemented to efficiently describe plants whose axis is oriented differently than north-south, as it is often assumed. Based on different optical efficiency definitions and real plant dimensions and parameters, a parametric analysis is here presented to investigate the effect of the plant orientation on its performance. The energy available at the receiver results to be reduced by 8.7% on a yearly basis when the system is oriented east-west instead of north-south; on the other hand, it has been observed that higher winter peak efficiencies and a more constant yearly production are achieved when the system is rotated with respect to the reference alignment.

Optical Modelling of a Linear Fresnel Concentrator for the Development of a Spectral Splitting Concentrating Photovoltaic Thermal Receiver

Concentrating photovoltaic thermal (CPVT) solar collectors can be regarded as a promising technology, as they are capable of providing renewable electricity and industrial heat simultaneously. The development of a novel CPVT receiver for a linear Fresnel concentrator requires detailed knowledge about the optical performance of the utilised mirror field. Therefore, this paper presents a generic optical model for such concentrating solar systems. The model was developed in MATLAB™ and calculates the sun’s position depending on the location, date and time. The subsequent geometrical computation of each mirror stripe angle is the basis for the detailed consideration of internal shading mechanisms that are typical for Fresnel mirror concentrators. Furthermore, the cosine losses are determined separately for each mirror. The outcomes of the developed model comprise the optical performance parameters of the considered Fresnel mirror field, such as the geometric efficiency, resulting irradiance in the receiver input plane, expected width of the focus image, concentration factor and total radiant flux impinging the receiver. Due to the chosen design of the model, its application is not limited to a particular kind of Fresnel concentrator. By contrast, all geometric parameters, such as the number of mirrors, the dimensions of the mirrors and the receiver, among others, can be freely adjusted.

Measure of the solar flux conveyed onto a lambertian target by a novel bi-axial fresnel concentrator

This paper deals with the optical analysis of a prototype of a novel concentrator, named as Bi-Axial Fresnel (BAF). This concentrator aims at reducing production and installation costs, as well as keeping as low as possible the weight and the bulk of the mirrors field, making it suitable for building small-dimensions systems, able to be placed on industrial roofs, as an example. The prototype is composed as an array of 3x3 mirrors. Its theoretical concentration is therefore 9. The experiment made use of a very basic equipment, which included a thermal flux sensor and a simple webcam, properly equipped for distinguish grey scales under quite high solar intensities. The concentrator was governed by an Arduino card, while the acquisition took place by means of a National Instruments acquisition board and Labview software. The aim of this experimental setup was the reconstruction of the solar flux on a fixed Lambertian target, based on the grey-scale maps gathered through the webcam and properly scaled accordingly to the punctual solar flux measured by the sensor. This way, the experimental apparatus was able to get an estimation of the solar power conveyed to the target.

Efficient sunlight harvesting with combined system of large Fresnel lens segmented mirror reflectors and compound parabolic concentrator without tracking sun for indoor daylight illumination

Sunlight is a great substitute for indoor artificial lighting during the daytime but still isn't so viable because of the cost of fiber-based daylighting system and its efficiency. In this paper, we report the design and development of a cost-effective non-mechanical tracking-based solar concentration system using a combination of a large Fresnel lens, segmented mirrors, and segmented compound parabolic concentrator (SCPC) for indoor daylighting application. This system presents the three-stage collection of sunlight by means of extending the collection aperture vertically while keeping the horizontal area same. First one is the concentrated light from the Fresnel lens, the second one is the direct sunlight incident onto the CPC and the third one is the direct sunlight reflected from the segmented mirrors onto the CPC. Hence the light transported through this system is adequate for illumination purposes inside the room. The manufacturing of ideal CPCs through the moulding process is both expensive and complex, and it necessitates extreme precision. Therefore, a cost-effective and efficient segmented CPC is designed and developed using a highly reflecting mirror-polished aluminum sheet which works well compared to the ideal CPC. To transport concentrated sunlight inside the room a highly reflecting horizontal light pipe is designed and developed. The collimated light at the output is challenging therefore, we have coupled inverted CPC at the exit of segmented CPC in the system. Further, to guide sunlight deep into the rooms we have coupled the entire system with a rectangular light pipe. An efficient diffuser is coupled at the end of the rectangular light pipe to illuminate the room uniformly. Various optical parameters such as illuminance, color rendering index (CRI), and correlated color temperature (CCT) values are analyzed from the result obtained which shows that the system can efficiently transport sunlight deep inside the room throughout the day. Therefore, the proposed system is very much helpful for the sustainable development of a country.

No-vacuum Mono-Tube Compound Parabolic Collector Receiver for Linear Fresnel Concentrator: Numerical and Experimental Approach for Dynamic Behavior Assessment

The present paper aims to develop a novel simplified transient model to investigate the dynamic behavior of a no-vacuum mono-tube receiver equipped with a compound parabolic collector. Considering the intermittency of solar radiation, predicting receiver thermal behavior is critical for linear Fresnel concentrator design and operation. From this standpoint, this research focuses on determining whether or not the steady-state assumption influences the receiver’s performance. Unlike the current models accounting for all the receiver components, the proposed model considers the absorber tube as the primary node and focuses on the heat transfer fluid temperature distribution. The remaining components form an equivalent thermal resistance through which heat loss occurs. The global heat losses are then characterized using an experimental receiver prototype with tube diameter of 70 mm, an aperture of 500 mm, and a secondary reflector. The overall receiver heat loss coefficient was determined at different absorber temperatures ranging between 60 and around 265 °C. The heat loss coefficients measured varied from 4.7 to 8.5 W/m2 K. The model computes receiver performance using the measured overall heat loss coefficient based on real solar data. The receiver response at steady and transient states has been conducted and discussed according to several design parameters, including the heat transfer fluid nature and mass flow rate, the receiver length, and the absorber tube thickness. For the same working conditions, synthetic oils fluid allows achieving higher efficiencies whereas molten salts enable reaching higher outlet temperatures. For the metal wall thicknesses ranging between 2 and 3 mm and the fluid outlet temperature varying between 250 and 300 °C, the receiver thermal efficiency during the day remains relatively close to 75 %. The impact of the absorber tube thermal inertia has been investigated by analyzing the dynamic behavior under various close-to-real-world scenarios. Results have shown that the steady-state assumption does not influence if the metal wall tube thickness is lower than 3 mm.

The development of Fresnel lens concentrators for solar water heaters: a case study in tropical climates

This paper discusses the application of Fresnel Lens Concentrator for Solar Water Heater which is a case study in Indonesia. The purpose of this study was to find an empirical equation of the relationship between Direct Normal Irradiance (Ib) and focal point temperature (Tf). The research location is Latitude: 7.9553 °S and Longitude: 112.6145°E. The SM-206 solar power meteris used.The Fresnel lenses are made of PMMA material. Its specifications are: diameter=1000 mm; weight=2 kg; thickness=2 mm; groove pitch=0.5 mm and focal length=880 mm.The main experimental setup consists of a PMMA Fresnel lens and a receiver. The conical cavity receiver has specifications; geometric concentration ratio,CRg=8, and V=2 Liters. Temperature measurement is done using a temperature data acquisition system. The K-type thermocouple is used to measure:
 1) ambienttemperature (Ta);
 2) the focal point temperature (Tf);
 3) receiverwall temperature (Tr);
 4) watertemperature (Tw).
 The experiment obtained the results of the empirical equation for the relationship between Direct Normal Irradiance (Ib) and focal point temperature (Tf). The increase in solar radiation produces a focus temperature, exponentially. At DNI 858 W/m2 it can produce a focal temperature of up to 1064 °C. The efficiency of the receiving cavity of the thermal cone which contains 2 litres of water and CRg=8 under conditions of relatively Direct Normal Irradiance ( =675 W/m²) is about 10.61 %. Furthermore, the energy that can be generated in heating water is 0.17–0.32 MJ, in 100 minutes. Heat convection and radiation loss can be reduced by adding an insulating layer to the walls and coating the surface with black

Thermal analysis using induction and concentrated solar radiation for the heating of metals

It is described the thermal analysis of a cylindrical workpiece involving the coupling of two heat sources. Induction heating was applied, which generated Eddy currents that circulated through the workpiece and heated the material surface. Also, concentrated solar energy heating was applied at the top of the workpiece, which generated a heat flux from the Fresnel lens concentrator. The formulation for the transient heat transfer analysis is presented. A numerical simulation for solving Maxwell's equations along with coupled and transient heat transfer conditions was developed using COMSOL Multiphysics®. The temperature distribution of the cylindrical workpiece was obtained, and the heating time was also determined. Subsequently, we compared this simulation and the experimental test. The experimental results show that for the coupling induction and concentrated solar energy, the temperature reaches its maximum faster than induction or concentrated solar energy alone. This kind of proposed alternative system can be useful for time and energy reduction for industrial heat treatments like annealing, precipitation hardening, quenching and tempering, isothermal treatments of ferrous and non-ferrous alloys.

Renewable Energy-Driven Desalination: New Trends and Future Prospects of Small Capacity Systems

New trends and future prospects for small capacity systems of Renewable Energy-driven DESalination (REDES) are reviewed and assessed in this paper over a nominal desalination capacity range of 3–1000 m3/d. A thorough literature review is reported in order to evaluate current research and developing activities. Outstanding commercial prospects in the near future are identified for two off-grid REDES technologies under development. First, wave energy converters with direct coupling to seawater desalination. Second, solar micro gas turbines with biofuel backup coupled to reverse osmosis (RO) desalination and/or zero liquid discharge water treatment. These systems, as well as mature REDES plants (namely PV/RO and wind turbines/RO), will benefit from forthcoming advances in energy efficiency in the RO process itself. The Closed Circuit RO desalination (CCROTM) concept may be a key configuration for enhancing RE-driven RO desalination. Additionally, opportunities for innovation in seawater RO desalination with variable power consumption are highlighted. On the other hand, our conclusions highlight opportunities for developing novel portable REDES systems based on solar membrane distillation with a portable linear Fresnel concentrator manufactured by SOLATOM. Additionally, the concept of portable systems could foster the commercial development of microbial desalination cells combined with solar PV energy and RO powered by tidal currents.