Linear Fresnel Research Articles

Impact of the variation of the receiver glass envelope transmittance as a function of the incidence angle in the performance of a linear Fresnel collector

In this paper, we focus on the variation of the transmittance of the receiver glass envelope as a function of the incidence angle and we measure its impact on the annual optical efficiency of a LFR plant using ray-tracing techniques. For this purpose, we draw up a detailed model of the LFR collector installed on the roof of the School of Engineering of the University of Seville, Spain. We also calculate the optical efficiency with and without a secondary reflector and with constant or variable transmittance receiver glass envelope properties.We run simulations using a clear-sky annual 1-min synthetic data set as input and calculate an average annual optical efficiency using efficiency matrices and Incidence Angle Modifiers (IAM) obtained from ray-tracing simulations. We find that the effect of the variation of the receiver glass envelope optical properties, as a function of the incidence angle, reduces the annual optical efficiency by 2.5%when the LFR plant has a basic secondary reflector and by 0.7% when there is no secondary reflector, according to the results obtained when using constant optical properties. We also evaluate the performance of the system with an optimised secondary reflector design.

A spectral-splitting photovoltaic-thermochemical system for energy storage and solar power generation

A hybrid solar energy conversion and storage system integrating a CdTe solar cell and methanol thermochemistry with a spectral filter assigning different parts of the solar spectrum is proposed. A thermodynamic model and an optical model are established to study the photovoltaic and thermal performance of this system. The results show that the system features high solar power generation efficiency (up to 39%) and good potential for solar thermal energy storage (up to 60%) as a result of both spectral filtering and the manipulation of individual linear Fresnel reflectors, which also considerably enhance control flexibility. Sensitivity analysis shows that the system remains highly effective in solar to power conversion against non-ideal conditions. The economic assessment indicates that the levelized cost of electricity is as low as $ 0.20/kWh.

Design and development of small-scale linear Fresnel solar concentrator for medium temperature applications

In recent years, Even if the CSP industry (Concentrated Solar Power) has not been yet developed as it should be in Morocco, this country is attaching an increasing importance and have launched ambitious development goals by the year 2020. Many applications of CSP technology needs operating temperatures up to 300 °C [1]. These applications include water heat especially for domestic needs.The present article shows the results of a work about the development of a low-cost concentrator taking into account Moroccan socio-economic context. The system designed and developed a combination uses of two CSP technologies: Parabolic Dish and Linear Fresnel Concentrator. To develop the prototype, a simplified model was used to define the dimensions as well as the number of mirrors that compose the system. The system is autonomous, modular and makes it possible to concentrate the solar radiation with automatic tracking of the sun. A set of mirrors focus sunlight onto a fixed absorber located at a common focal point which is adjustable and allows connecting different types of absorbers. This paper is detailing the design of the devloped prototype. The system is innovative and operates at temperatures up to 250 °C. It is easy to meet the household hot water needs as per Moroccan natural conditions.The paper describes the modelling approach, presents the comparison of simulation results with real measurements and evaluates the results.

Solar Collectors Modeling and Controller Design for Solar Thermal Power Plant

Electric power generation techniques utilizing solar energy urge scientists to research and develop technologies using sustainable resources on a large scale with qualities close to the ideal resource. Solar collectors are crucial components of a Solar Thermal Power plant (STP) which are required to be within a certain feasible range in order to operate and provide solar thermal resources and intermittent inputs. The closed-loop controller design for solar collectors enhances the lifespan of STP. This paper presents first principle modeling of Parabolic Trough Collector (PTC) using therminol oil and Linear Fresnel Reflector (LFR) design using water as working fluid. Using step test method linear transfer function obtained at continuous and discrete domain nominal operating range. A continuous Proportional Integral (PI) controller is designed either with Static Feed Forward (SFF) control or with Predictive Function Control (PFC). Optimal performance of the controller is based on performance indicators obtained through various case studies.

Advanced exergoeconomic analysis of solar-biomass hybrid systems for multi-energy generation

In this study, advanced exergoeconomic analysis of solar-biomass hybrid energy systems for the northern part of Cameroon is conducted. Three concentrating solar power (CSP) technologies, parabolic trough collector (PTC), linear Fresnel reflector (LFR) and solar tower (ST), hybridised with biomass-fired (BF) technology are investigated. It is found that exergy destruction from the solar field alone is responsible for the most of the whole exergy destructions (86.3% for PTC-BF, 92.2% for ST-BF and 85.4% for LFR-BF). The results show that LFR-BF hybrid system is the best cost-efficient system while ST-BF hybrid system is the worst cost-efficient system considering initial investment, avoidable-endogenous exergy destruction, cost associated with avoidable-endogenous exergy destruction and total cost required for the optimisation.

Entropy generation analysis for forced convection boiling in absorber tubes of linear fresnel reflector solar thermal system

A methodology has been presented related to entropy generation due to forced convection boiling in long absorber tubes used in linear Fresnel reflector solar thermal system. Variable heat flux has been applied on the tube which replicates the scenario for aforementioned tubes and local entropy generation has been obtained for various parameters. Mathematical modeling has been made separately for single-phase and two-phase regions in flow boiling conditions encountered in linear Fresnel reflector tubes. Entropy generation in two-phase region has been formulated using homogeneous equilibrium model. The entropy generation at varying mass flux and heat flux cases are calculated. The entropy generation due to heat transfer is found to be more than that of pressure drop. Still, entropy generation due to pressure drop in two-phase region plays a major role of increasing nature of it. Present approach will help researchers and industry to optimize the solar thermal systems where flow related phase change occurs and measures can be taken accordingly to increase energy efficiency of those systems.

Supercritical CO2 Mixtures for Advanced Brayton Power Cycles in Line-Focusing Solar Power Plants

This work quantifies the impact of using sCO2-mixtures (s-CO2/He, s-CO2/Kr, s-CO2/H2S, s-CO2/CH4, s-CO2/C2H6, s-CO2/C3H8, s-CO2/C4H8, s-CO2/C4H10, s-CO2/C5H10, s-CO2/C5H12 and s-CO2/C6H6) as the working fluid in the supercritical CO2 recompression Brayton cycle coupled with line-focusing solar power plants (with parabolic trough collectors (PTC) or linear Fresnel (LF)). Design parameters assessed are the solar plant performance at the design point, heat exchange dimensions, solar field aperture area, and cost variations in relation with admixtures mole fraction. The adopted methodology for the plant performance calculation is setting a constant heat recuperator total conductance (UAtotal). The main conclusion of this work is that the power cycle thermodynamic efficiency improves by about 3–4%, on a scale comparable to increasing the turbine inlet temperature when the cycle utilizes the mentioned sCO2-mixtures as the working fluid. On one hand, the substances He, Kr, CH4, and C2H6 reduce the critical temperature to approximately 273.15 K; in this scenario, the thermal efficiency is improved from 49% to 53% with pure s-CO2. This solution is very suitable for concentrated solar power plants coupled to s-CO2 Brayton power cycles (CSP-sCO2) with night sky cooling. On the other hand, when adopting an air-cooled heat exchanger (dry-cooling) as the ultimate heat sink, the critical temperatures studied at compressor inlet are from 318.15 K to 333.15 K, for this scenario other substances (C3H8, C4H8, C4H10, C5H10, C5H12 and C6H6) were analyzed. Thermodynamic results confirmed that the Brayton cycle efficiency also increased by about 3–4%. Since the ambient temperature variation plays an important role in solar power plants with dry-cooling systems, a CIT sensitivity analysis was also conducted, which constitutes the first approach to defining the optimum working fluid mixture for a given operating condition.

Design and Comparative Techno-Economic Analysis of Two Solar Polygeneration Systems Applied for Electricity, Cooling and Fresh Water Production

Two solar polygeneration systems were investigated for electricity, cooling and fresh water production. In the first scenario ( LF PS ), the linear Fresnel (LF) solar field was used as thermal source of the Organic Rankine Cycle (ORC), absorption chiller (ACH) and multi-effect desalination (MED) unit. In the second scenario ( PV PS ), photovoltaic (PV) panels were considered as the electricity source to supply the electricity load that is required for lighting, electrical devices, compression chiller (CCH) and reverse osmosis (RO) units. A techno-economic comparison was made between two scenarios based on the land use factor (F), capacity utilization factor (CUF), payback period, levelized cost of electricity (LCE), levelized cost of cooling energy (LCC) and levelized cost of water (LCW). The calculations were conducted for four different locations in order to determine the effect of solar radiation level on the LCE, LCC and LCW of systems in both scenarios. The results showed that the LCE and LCW of PV PS is lower than that of LF PS and the LCC of LF PS is lower than that of PV PS . Also, the payback period of LF PS and PV PS systems are obtained as 13.97 years and 13.54 years, respectively, if no incentive is considered for the electricity sale.

Study of Kinematic System for Solar Tracking of a Linear Fresnel Plant to Reduce End Losses

Study of Kinematic System for Solar Tracking of a Linear Fresnel Plant to Reduce End Losses

Analysis of Potential Use of Linear Fresnel Collector for Direct Steam Generation in Industries of the Southwest of Europe

Industry sector has an important impact on primary energy consumption at the international level, and solar energy constitutes a real alternative to cover these energy needs partially. Among thermosolar concentration technologies, Linear Fresnel Collector (LFC) technology has some advantages that make it more accessible to industries. With the aim of providing new tools for easier decision-making processes, in the present work, several energy audits were carried out in industries (located in the south-west of Europe, with considerable steam consumptions), quantifying thermal and energy consumptions and defining both work schedules and seasonality. Afterwards, a comparison based on three factors was carried out: Thermal consumption regarding total industry consumption, the performance of the work during the solar schedule, and the quantification of the monthly average concentrated energy for a certain LFC facility. The analysis carried out according to these criteria showed different results for each case, making a global assessment necessary to suitably ponder each factor. This analysis ranked tomato industries as the most suitable for LFC technology, due to the fact that their main operating period was during the months with the highest solar isolation, and the solar schedule was completely integrated in a 24-h working day. Also, industrial waxes and laundries showed a good combination of both facts.

Introducing an integrated SOFC, linear Fresnel solar field, Stirling engine and steam turbine combined cooling, heating and power process

A new integrated combined cooling, heating and power system which includes a solid oxide fuel cell, Stirling engine, steam turbine, linear Fresnel solar field and double effect absorption chiller is introduced and investigated from energy, exergy and thermodynamic viewpoints. In this process, produced electrical power by the fuel cell and steam turbines is 6971.8 kW. Stirling engine uses fuel cell waste heat and produces 656 kW power. In addition, absorption chiller is driven by waste heat of the Stirling engine and generates 2118.8 kW of cooling load. Linear Fresnel solar field produces 961.7 kW of thermal power as a heat exchanger. The results indicate that, electrical, energy and exergy efficiencies and total exergy destruction of the proposed system are 49.7%, 67.5%, 55.6% and 12560 kW, respectively. Finally, sensitivity analysis to investigate effect of the different parameters such as flow rate of inputs, outlet pressure of the components and temperature changes of the solar system on the hybrid system performance is also done.

A review of Thermal Performance of Solar Concentrator – the future needs

Abundant solar energy is freely available almost round the year in India. As per the current scenario of global warming and climatic change, solar energy is the cleanest source in nature. Concentrated solar power (CSP)has hardly contributed to the overall installed solar power capacity in the country. CSP technologies are Parabolic Trough Collector (PTC), Linear Fresnel Reflector (LFR), Paraboloid Dish and Solar Power Tower. This paper presents a review of CSP in solar parabolic dish concentrator to understand thermal aspect like thermal efficiency, optical efficiency, useful heat gain, heat losses, solar irradiation, etc. for various applications and current development. The current scenario of global CSP is discussed to meet the future challenges and need of the society.

Design, economic, and environmental assessments of linear Fresnel solar power plants

AbstractIn the present work, the design‐environmental and economic (D2E) comparative study of seven different configurations of Linear Fresnel solar thermal power plants using two‐generation modes (direct and indirect steam generation) with nine various working fluids, with and without integrated thermal energy storage or/and backup fuel system is presented, with minimum levelized cost of energy (LCOE) as objective. This study is based on a power plant of capacity of 50 MW. A sensitivity analysis is developed to optimize the solar multiple of the solar field, Fossil fuel fraction of backup system (BS), and TES hours capacity, using System Advisor Model software. The results show that the wrong choice of plant's components and inexact performance optimization lead to the increasing cost of electricity generated due to operating costs and additional investments. The BS was the most significant contributor to greenhouse gas emissions at all sites, contributing over 90% of total emissions, due to its relative contribution (95 kg/MWh). Finally, the combination of the storage and BSs in molten salt mode makes it more competitive under Algerian climates, which confirms that molten salt linear Fresnel solar plant with 25% of a BS and 6 hr of the storage system is the best and optimum solution.

An experimental implementation and testing of a concentrated hybrid photovoltaic/thermal system with monocrystalline solar cells using linear Fresnel reflected mirrors

An experimental implementation and testing of a concentrated hybrid photovoltaic/thermal system with monocrystalline solar cells using linear Fresnel reflected mirrors

Experimental evaluation of solar thermal performance of linear Fresnel reflector

The solar thermal performance of a 102 kW rated thermal capacity linear Fresnel reflector system was evaluated experimentally under fixed and variable airflow rate through the oil-air heat exchanger. The solar thermal system consisted of 240 mirrors (linear Fresnel solar reflectors), each of 1485 by 625 mm size to heat the thermal oil, which was used to heat the air using the oil to air heat exchanger (AFfE). The results show that the actual maximum efficiency of the solar collector lies in the range of 0.28 to 0.34, whereas the calculated one is about 0.54 for the variable airflow rates. However, for a fixed airflow rate, the actual maximum efficiency is between 0.26 and 0.30. It implies that the actual solar collector efficiency is much lower than the calculated values. One of the major factors, which is not accounted for in the theoretical efficiency calculation, is the effect of dust on the primary and secondary mirrors. The investigated site is observing considerable sand movement, which is affecting the thermal output of the solar collector. The maximum heat exchanger effectiveness, e, obtained for variable and fixed airflow conditions is 0.9 and 0.8, respectively.

Introducing and investigation of a combined molten carbonate fuel cell, thermoelectric generator, linear fresnel solar reflector and power turbine combined heating and power process

Abstract In the present study, a combined heat and power process consists of molten carbonate fuel cell, thermoelectric generator, linear Fresnel solar reflector and power turbine is introduced and investigated from energy, exergy and thermodynamic points of view. Fuel cell produces electrical and thermal power. A part of waste heat from the fuel cell is sent to the thermoelectric generator to produce additional power and the remaining enters the environment. The solar field as a heat exchanger generates a part of the required thermal power of the proposed process. Linear Fresnel solar reflector with duty of 1728 kW is used too. Numerical modeling and thermodynamic analysis of the proposed system is done using MATLAB and HYSYS softwares, respectively. The results were discussed in two scenarios: (1) investigation of fuel cell and thermoelectric generator hybrid system and (2) investigation of whole combined heat and power process. Results indicate that the overall and electrical efficiencies of the proposed system are 64.93% and 31.57%, respectively. Also, in this process, 41728.8 kW of exergy is destroyed and the process total exergy efficiency is gained 0.12%. Finally sensitivity analysis of the fuel cell, turbines, solar system and thermoelectric generator against effective parameters is investigated.

Experimental and optical performances of a solar CPV device using a linear Fresnel reflector concentrator

A solar CPV device using a linear Fresnel reflector (LFR) concentrator is described. The design principle of the concentrator is provided. The solar concentrating processes are simulated by using the MCRT approach. A small scale test rig of the concentrator is constructed to investigate the actual optical and I–V performances of the CPV device. Both of the simulation and experimental results reveal that the proposed concentrator has a relatively high solar concentrating uniformity. The configuration and optical analyses of the concentrator are launched. The results show that the geometric concentrating ratio and ground utilization ratio both increase with the solar panel installing height increased. When the solar cell height is settled, the maximum value of ground utilization ratio exists with the mirror field width increased. The sun-tracking accuracy effect analysis is also carried out. The results indicate that the normalized optical efficiency of the CPV system using the LFR concentrator can be 0.62 or higher when the tracking error is less than 1°. A solar cell monomer and a cell module are used to carry out the I–V experiments. The test results of their energy conversion efficiencies are 14.7% and 13.6%, respectively.

Hybrid Solar Cells with a Sunlight Concentrator System

Hybrid solar cells based on InGaP/Ga(In)As/Ge multijunction structures integrated into crystalline Si heat-removal base and provided with sunlight concentrator system based on linear Fresnel lenses and carboplastic mount structure have been developed and investigated. The hybrid solar cells with sunlight concentrators in the photovoltaic module provide a specific electric power of 390 W/m2 (AM0, 1367 W/m2) at a photoconverter unit specific weight reduced to 1.0 kg/m2. Improved photovoltaic characteristics and high radiation resistance allow using the proposed hybrid solar modules with sunlight concentrators in space solar batteries and autonomous power supply facilities.

Design, Manufacturing and Characterization of Linear Fresnel Reflector’s Facets

This paper presents a procedure for making facetted mirrors to use in linear Fresnel reflectors, considering the design of the transversal geometry, materials, and structure configuration. Four different assemblies of the structure that supports and shapes the mirror are documented and evaluated. An assembly that implies a curved, pleated aluminum rectangular plate with a thin silvered-glass mirror vacuum glued to the plate is defined as the optimal. The geometrical quality of the chosen mirror facet’s configuration is accomplished by photogrammetry.

Energy and financial investigation of a cogeneration system based on linear Fresnel reflectors

The objective of the present work is the investigation and the optimization of a cogeneration system with solar linear Fresnel reflectors. The examined system produces electricity by utilizing an organic Rankine cycle and cooling by utilizing a single-effect absorption chiller with the working pair lithium-bromide/water. The system is studied parametrically in steady-state conditions by using a developed model in Engineering Equation Solver which has been validated by literature data. The next step in this work is the optimization (with energy and financial criteria) in dynamic conditions for the climate conditions of Athens (Greece). Different combinations of collecting areas and storage tanks are applied in order to determine the best combination in every case. Moreover, critical parameters such as the working fluid in the organic Rankine cycle, the saturation temperature in the heat recovery system and the generator temperature level in the absorption chiller are studied. The best design according to net present value maximization includes 140 m2 collecting area, a storage tank of 1.4 m3 and toluene in the organic Rankine cycle with 290 °C saturation temperature. In this case, the net present value is around 8 k€, the yearly mean energy efficiency is 17.5%, the yearly mean exergy efficiency is 8.3% and about 18 MWhel are produced on a yearly basis.