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In the present study, a zero-dimensional thermal model has been developed to analyze a novel low concentration photovoltaic-thermal (CPVT) collector. The model has been developed by driving heat transfer and energy balance equations for each part of the collector and then solving all the equations simultaneously. Moreover, a Monte-Carlo ray-tracing software has been used for optical stimulations of the parabolic trough solar collector. The novel CPVT collector has been experimentally tested at Gavle University (Sweden) and the model has been validated against the experimental results. The primary energy saving equivalent to the thermal-electrical power cogeneration of the CPVT collector has been determined. The effect of glass cover removal, heat transfer fluid (HTF) inlet temperature and mass flow rate on the collector performance has been investigated. The optimum HTF mass flow rates of the collector for maximum electrical yield and overall primary energy saving were determined under specified operating conditions by considering the pump consumption. The effect of mean fluid temperature on the thermal and electrical efficiencies has been studied and the characteristic equation of the thermal efficiency has been obtained. The thermal and electrical peak efficiencies of the collector have been found to be 69.6% and 6.1%, respectively.

The industrial sector is one of the biggest oil consumers in Cyprus, corresponding to 20% of the fuel consumption. A parabolic trough collector (PTC) system seems the best option to produce clean thermal energy at higher temperatures than those that can be achieved from the already widely used flat plate collectors on the island. This paper presents a simulation model built to investigate the performance of the first industrial PTC system in Cyprus, installed at the Cyprus biggest soft drinks factory. The simulation model is built in TRNSYS and is validated using data from the real PTC system installed at the factory. The results show a very good fitting between the operating parameters and the power output of the Solar Field (SF), Concrete Thermal Storage System (CTES), and the Steam Generator (SG). The average percentage relative error of the system's contribution to the process is less than 6.32% for the daily steam production and during a week did not exceed 6.45%. The novelty of this study is the development of a design tool that can be used by potential interested industries to identify the suitable system that fits their needs. All data are provided in the form of graphs and allow anyone to use as input data the thermal energy demand and required steam temperature of the industry to retrieve information about the size of a suitable system which satisfies these requirements depending on each case. The payback period for all cases examined varies from 2 to 6 years, depending on the size of the system.

This paper investigates the dynamic behaviour of a low pressure open natural circulation loop applied to a parabolic trough collector. An in-house experimental setup is developed to perform the test. The experiments are performed on two distinct modes: H-mode and S-mode, corresponding to single-phase and two-phase flow. Three distinct power amplitude modes viz, 250, 325, and 464.3 W with a power step number of 24, 18 and 12 having a duration of 15, 20 and 30 min are considered. A Fast Fourier Transform analysis revealed that the flow in the loops is stable with a maximum decay ratio of 0.726. Instabilities, including Density Wave Oscillation, geysering and flashing, are observed during the test. Moreover, the thermal inertia of the loop has a significant role in the initial stage of power steps. An increase in the power step size conferred a 9.1%–33.4% increase in the outlet temperature of water in H-mode. In S-mode, an increase in power step size delayed the onset of boiling and reduced the duration of boiling by 2.8–14.32% and 8.03–22.02%. The loop can generate a mass flux of 40–42.5 kgm2s−1 in H-mode and up to 400 kgm2s−1 in S-mode, which is significant.

For solar concentrating photovoltaic applications, line-focusing collectors, such as parabolic trough collectors, can accommodate greater numbers of PV cells at their focus compared to point focusing collectors. However, there is a dearth of research related to homogenizing the flux distribution in such collectors. Therefore, this paper aimed to develop a method for optimizing the shape of a concentrator that has the same geometrical characteristics as a parabolic trough concentrator (PTC) but high flux homogeneity. The customization of the curve was controlled by introducing guide points and forming a curve passing through these points using the Newton Interpolation Polynomial. The ray tracing was then used to obtain the concentration ratio ( ) and the solar flux distribution uniformity factor ( ) for the customized concentrator as performance factors. Then, the location of guide points was optimized using the Particle Swarm Optimization algorithm to achieve the greatest value of . The results showed that the shape of a PTC having and can be optimized to produce a concentrator having nearly the same value of but , which is ~10 times better. An online computer tool for the evaluation purpose was also developed and has been made available to use for free.

The paper aims to solve drawbacks associated with Gas Turbine GT by integrating a novel cascaded system into a combined cycle simultaneously. Parabolic trough collectors preheat the air at the combustion chamber inlet, then drive an absorption inlet-air cooling cycle that controls the ambient-air temperature at the compressor's inlet. This study uses the 2nd law of thermodynamics to estimate the maximum available energy, calculate the electric exergy efficiency, and explore the maximum irreversible exergy destruction in the system's components. Artificial Neural Network was employed to develop a multi-objective optimization by linking data collected from equations in the Engineering Equation Solver software with Matlab. Spider diagrams investigated the effect of varying several key operating parameters on the performance of the system, identifying gas turbine as the highest irreversibility sub-unit and the solar field parabolic trough collectors as the second. Design improvement for the combustion chamber can reduce 303.6 MW, and for parabolic trough collectors field reduce 58.9 MW. Artificial neural networks with multi-objective optimization maximized the electric exergy destruction to 46.19% and minimized the exergy destruction to 489.4 MW, relative to the corresponding values from the simple design point.

The thermal and economic performance of parabolic trough collectors (PTCs) and PTCs with double glass envelope (DGE-PTCs) are analyzed in this work. A model including thermal and optical effects is developed to evaluate the efficiency of vacuum and air-filled DGE-PTCs, while an economic model based on two commercial PTCs (SkyTrough and Ultimate Trough collectors) was developed to assess the economic performance. The efficiency and thermal output per unit cost of the proposed DGE-PTCs are analyzed as a function of the concentration ratio and are respectively compared with the thermal and economic performance of traditional and commercial PTCs. The optimum concentration ratio for maximum thermal performance varies from 11.0 to 23.3 for operation temperatures ( T H T F ) between 100 °C and 400 °C, while the optimum concentration ratio for maximum economic performance ranges between 28.9 and 33.2 for the SkyTrough and between 40.0 and 43.8 for the Ultimate Trough collector designs. The DGE-PTCs present higher thermal and economic performance at high operating temperatures, which presents a valuable opportunity for implementation in new PTC designs pursuing higher operating temperatures to achieve superior thermal cycle efficiencies.

This paper presents enhanced design for Automation control of processes involved in a solar system which utilizes programmable logic controller to automate tracking system for obtaining maximum solar radiation. Three areas are involved in this proposed multi area system where first and second area considers solar power plant with thermal system based parabolic trough collector with fixed solar isolation and random isolation of solar energy whereas third area comprises of solar thermal system with dish Stirling realistic unit. Energy efficiency can be increased by using solar concentrator along with Stirling engine. Optimization of gain of the controller is by utilizing crow search novel algorithm. Crow search algorithm is an optimization technique, which provides better performance at complex time varying noisy condition and time in-varying noisy condition. The Proposed controller is evaluated by obtaining the optimized parameters of the system whose comparison is done by operating proposed controller with & without renewable sources of energy thereby revealing better performance for both conditions. Testing is done in different areas with fixed solar isolation and random stisolation of solar energy involved in solar thermal power plant based on parabolic trough collector. Gain and parameters of the controller of the solar power plant are optimized by utilizing automation for operation of solar concentrator with parabolic Trough collector. Data acquisition and monitoring is done by human machine interface (HMI) in order to report safe operation. The Simulation results of integrated solar thermal system involving dish Stirling with parabolic trough collector, shows that dynamic response of the proposed controller operating with renewable solar energy is better than that of non-renewable energy source.

The risk of vacuum loss in linear solar heat collection elements (HCEs) is one of the major practical challenges that are facing the parabolic trough solar concentrator (PTSC) systems in concentrating solar power (CSP) plants. Despite the long-life span of CSP systems, HCEs are frequently replaced due to permeated hydrogen (due to saturation of getters) or leaked air (due to failures in end metal-to-glass welding or cracked glass shells). This study proposes a low-tech solution for boosting the performance of PTSCs with partial or lost vacuum through rotating the HCEs. A carefully validated integrated 3D optical-thermal model is developed and used to quantify the energetic and exergetic performances of PTSCs with rotated and fixed HCEs for both cases of lost and maintained vacuum. Both steady and unsteady simulations are reported using high-precision ground measurements of direct irradiance and meteorological parameters. As the rotational speed increases from 0 to 20 rad/s, the energy efficiency of PTSCs with new and damaged HCEs is improved by ∼47 and 52%, respectively, at a Reynolds number of 4000 and an inlet temperature of 350 °C. By rotating a damaged HCE at only 10 rad/s, maximum improvements of ∼26 and 53% in the useful heat gain are obtained, compared to non-rotating evacuated and non-rotating damaged HCEs, respectively, at the same operating conditions. Overall, the advantage of the proposed concept is more pronounced when the PTSC is operating at relatively low flow rates, high temperatures, or under high irradiance levels.

An integrated solar combined cycle system based on parabolic trough solar collector and combined cycle power plant is proposed. The advanced system is socio-economic significance compared to traditional combined cycle power system. Plainly, the exergetic analyses (exergy destruction and efficiency) via conventional and advanced methods are used for thermodynamic properties of the integrated solar combined cycle system components. In addition, the exergy destruction is divided into endogenous, exogenous, avoidable, and unavoidable. The results show that the combustion chamber has the largest fuel exergy and the highest endogenous exergy destruction rate of 1001.60 MW and 213.87 MW, respectively. Additionally, the combustion chamber has the highest exergy destruction rate of 235.60 MW(60.29%), followed by the parabolic trough solar collector of 54.20 MW(13.87%). For overall system, the endogenous exergy destruction rate of 320.83 MW (82.10%) and exogenous exergy destruction rate of 69.97 MW (17.90%) are resulted via the advanced exergy analysis method. Besides，Several methods to reduce the exergy destruction and improve the components’ efficiency are put forward.

This article presents a numerical analysis on the thermohydraulic and thermodynamic performance of a parabolic trough solar collector (PTSC) receiver's tube equipped with wavy promoters. A computational fluid dynamics (CFD) with the aid of finite volume method (FVM) is adopted to examine the flow and thermal features of the PTSC's tube receiver. The Reynolds number in the range of 5000–100000 with four fluid inlet temperatures in the range of 400–650 K are utilised. Three different advanced hybrid nanofluids (Fe2O3-GO, Fe2O3–SiC and Fe2O3–TiO2) dispersed in Syltherm oil 800 are employed inside the PTSC's receiver tube. The numerical outcomes are verified with the available correlations and with other numerical and experimental data available in the open literature. The numerical results reveal that the utilisation of wavy promoters inside the PTSC's receiver tube can significantly augment the thermal performance, where the average Nusselt number is improved by 150.4% when utilising Fe2O3-GO/Syltherm oil hybrid nanofluids at 2.0% concentration instead of Syltherm oil. Furthermore, the maximum reduction in the absorber's average outlet temperature is in the range of 7–31 °C. The overall thermal evaluation criterion (PEC) is found to be in the range of 1.24–2.46 using bricks-shaped nanoparticles. The results show that the thermal efficiency increased by 18.51% and the exergetic efficiency increased by 16.21%. The maximum reduction in the entropy generation rate and the entropy generation ratio are about 48.27% and 52.6% respectively. New correlations for Nusselt number, friction factor and thermal efficiency for PTSC tube having wavy promoters using hybrid nanofluids are developed.

This work aims to compare the cost and performance of Photovoltaic (PV) and Concentrated Solar Power (CSP) solar plants utility-size >100 MW built in the United States (US) and model predictions to forecast their optimal synergetic use in a near-future solar (and wind) only grid. There are in the country very few CSP, and many more PV plants, that are representative of the latest technologies. The largest number of PV plants is the result of the cost advantage and better technology-readiness, compared to the mistakenly promoted CSP solar tower (ST) with thermal energy storage (TES) plants, while neglecting the CSP parabolic trough (PT), and not factoring dispatchability. Without TES, CSP PT could provide comparable performances, at an acceptable cost, reaching the mass production of current PV technology. The addition of TES, still suffering from maturity issues, adds dispatchability, is a huge added value but at increased cost and reduced reliability. It is concluded that further technological progress and mass production of CSP, both PT and ST, with further expanded TES, is needed, targeting dispatchability. These plants should be coupled to PV production during the daytime to progress towards a stable solar energy supply with limited external battery energy storage.

This paper investigates the effect of slits within the arc-plug insert of the solar parabolic trough receiver (PTR). In order to predict the performance of the parabolic trough collector (PTC) with arc-plug slits within the absorber tube; two different variants of slits of 2 mm and 1 mm thicknesses are considered. Then, each of the variants of slits with different thicknesses are varied in terms of numbers of their occurrence in the arc-plug. The 2 mm thickness slits are varied in 5, 7, and 9 numbers with uniform space of separation between them in the arc-plug. While 1 mm thickness slits are varied from 11 to 13 in numbers and also maintaining uniform space of separation between them like in 2 mm thickness slits. The objective is to determine the effects of viscous dissipation within the slits of the arc-plug of PTR; and also, the optimized version of the slit with its numbers. It is found that 2 mm slits with 9 in numbers showed the highest value of thermal efficiency as compared to all other cases. The thermal efficiency (η) of the PTC with arc-plug slits are seen to be about 1.642 times of conventional PTC; whereas, 1.309 times of arc-plug without slits. Therefore, it is always beneficial to use slits within inserts of PTCs for its performance enhancement; but, the selection of slit’s thickness and its numbers plays a vital role in its application.

This paper aimed to perform a numerical study on a solar thermochemical reactor with Parabolic Trough Concentrator (PTC) for Methanol Steam Reforming (MSR) while taking into account the impacts of Cu nanoparticles. The optical analysis was initially performed by considering the volumetric heat flux with various irradiation and nanoparticle volume fractions. The reactor performance was then optimized by changing a few parameters, including the volumetric solar heat flux, the percentage of nanoparticles, and the inlet temperature. The present work also investigated the species concentration, temperature distribution, reaction rate along the reactor, and selectivity of hydrogen regarding the stated parameters. The numerical solution was obtained based on the finite element analysis and the direct MUMPS algorithm by the LU factorization method. The heat flux from the concentrator and reaction rate of the MSR reactor was validated, and the results were consistent with the literature exhibiting the minimum and maximum error values of 3.3% and 13.2%, respectively. The analysis revealed that the reactor efficiency decreases as the volumetric heat flux increases, which was relative to the variation of nanoparticle volume fraction. On the other hand, increasing the nanoparticle volume fraction increased the reactor efficiency at constant volumetric heat flux. The reactor efficiency was shown to be equal to 46.3% in the optimal state, which was relative to the heat flux of 4500 (W/m2), the nanoparticle volume fraction of 2%, and the solar irradiation range of 420–580 (W/m2).

Increasing the aperture of the parabolic trough concentrator (PTC) can effectively reduce costs and help promote. This paper proposed a circle and semicircle absorber tubes (AT) with a flat reflector (FR) in it for the large-aperture PTC system and the size of the AT was determined for the PTC with 8 m aperture width and 80° half rim-angle. The result shown the PTC system using a semi-circular AT with a diameter of 100 mm has the highest average thermal efficiency of 71.6% with DNI 400–1000 W/m2 at about 500 °Cand has best uniformity of 38.8%. However, its deformation is highest and 1.7 and 1.6 times other two ATs. Therefore, how to reduce the deflection has become a research direction in the future. Currently, the circular AT with a diameter of 80 mm is the most practical with an average thermal efficiency of 69.1% and a minimum deflection.

In this study, a new hybrid solar preheating intercooled gas turbine (SP-IcGT), is presented, in which a parabolic trough solar technology is used to preheat the compressed air before entering the combustor. The performance of the new hybrid gas turbine was evaluated and compared with the conventional hybrid solar preheating gas turbine (SP-GT). Several performance indicators were used in the analysis under Guangzhou (China) weather data. It is observed that the SP-IcGT is superior to the SP-GT system as it can boost the fuel-based efficiency by 19.35% versus 0.26% for the SP-GT system. In addition, the SP-IcGT has a much lower specific fuel consumption (about 7017 kJ/kWh) compared with the 10362 kJ/kWh for SP-GT. The highest fuel-based efficiency of 51.4% is obtained for the SP-IcGT with 47.4% improvement over the SP-GT, which exhibits a levelized electricity cost of 4.58 US/kWh. Meanwhile, fuel consumption and greenhouse gas emissions can be reduced greatly by integrating solar energy with the intercooled gas turbine. The SP-IcGT is more economical than applying carbon capture to the equivalent conventional gas turbine plant combined while achieving the same reduction of CO2 emissions. Overall, the SP-IcGT is an attractive system under different climates.

In solar parabolic-trough plants, the use of Model Predictive Control (MPC) increases the output thermal power. However, MPC has the disadvantage of a high computational demand that hinders its application to some processes. This work proposes using artificial neural networks to approximate the optimal flow rate given by an MPC controller to decrease the computational load drastically to a 3% of the MPC computation time. The neural networks have been trained using a 30-day synthetic dataset of a collector field controlled by MPC. The use of a different number of measurements as inputs to the network has been analyzed. The results show that the neural network controllers provide practically the same mean power as the MPC controller with differences under 0.02 kW for most neural networks, less abrupt changes at the output and slight violations of the constraints. Moreover, the proposed neural networks perform well, even using a low number of sensors and predictions, decreasing the number of neural network inputs to 10% of the original size.

Daily start-up is a typical feature of concentrated solar power plants (CSPs) due to solar energy intermittency. Therefore, appropriate start-up operation strategies are significant for CSPs. A parabolic trough concentrated solar power plant (PTCSP) with molten salt (MS) is a potential technical route. However, little attention has been paid to the dynamic start-up performance of PTCSP using MS. To mend the research gap, the dynamic start-up simulation of PTCSP using MS is conducted. Main contributions of this study are the dynamic start-up simulation of PTCSP using MS and evaluation of two MS anti-freezing solutions. Results indicate that the outlet MS temperature of solar field transiently exceeds nominal values during start-up processes. The inlet feedwater temperature of the preheater is much lower than MS freezing temperature during start-up processes. Therefore, two anti-freezing solutions were used to avoid MS solidification. Compared with utilizing the recirculating pump, utilizing the low-load regenerative heater can enhance anti-freezing performance, which could reduce the maximum control deviation of the preheater inlet feedwater temperature by 2.0 °C and increase the average outlet MS temperature of the preheater by 2.4 °C. This study may provide guidance for the dynamic simulation and operation optimization of CSPs during start-up processes.

The choice of condenser cooling option for concentrating solar power (CSP) plants is likely to affect their techno-economic feasibility. In view of this, an attempt has been made to assess relative techno-economics and net life cycle CO2-eq emissions mitigation (LCCM) potential for 50 MW nominal capacity wet-cooled and dry-cooled parabolic trough solar collector (PTSC) and dry-cooled solar power tower (SPT) based CSP plants with 6.0 h of thermal energy storage for two potential locations in India. It was observed that though dry cooling is likely to save significant amount of water (∼92%) in PTSC based plants, the same shall result in higher capital cost, higher performance penalty and higher parasitic power requirements leading to around 20% higher levelized cost of electricity (LCOE) as compared to wet-cooled PTSC based plants. It was also observed that the dry-cooled SPT based plants shall be able to deliver up to 4.5% higher annual electricity output and LCOE is also likely to be lowered by 13% than wet-cooled PTSC based plants. Considering emissions embodied and emissions associated with water transport/extraction from the source and water treatment, the estimation of LCCM from the PTSC and SPT based CSP plants have also been undertaken.

Improving efficiency and yield of a parabolic trough collector (PTC) field is of paramount technological importance. Here, an attempt toward this goal is made through combined optical and thermal simulation. Two major factors that affect the performance of an individual trough are mass flow rate and aperture width, which scales with rim angle. Performance of PTC-field is observed to have a non-linear scale-up rule as opposed to the same for an individual trough. Wider aperture leads to higher heat collection for individual trough; however, the same results in higher inter-trough shading limiting the number of troughs in a field and the effective unshaded hours. It also depends on insolation and latitude. Therefore, there lies a possibility of trade-off where flow rate, rim angle and design hours of operation require careful tuning to maximize annual energy yield. Here, a step by step procedure is demonstrated for Kanpur, India where optimal values of flow rate, rim angle and hours of operation are obtained to be 1.1 kg/s (for Syltherm 800 as the heat transfer fluid), 70° and 4 h around solar noon on winter solstice day, respectively. The methodology is illustrated to be generally applicable to any location or working fluid.

Concentrated Solar Power (CSP) Technology is a carbon-neutral, renewable energy source that can cover the high electricity demand even after sunset by utilizing only the sun's power. Although parabolic trough is the most established and used CSP technology, Solar Power Tower (SPT) is gaining maturity and popularity in recent years at the commercial level. The heliostat field's design is the most crucial design consideration for an SPT plant and is investigated in this study. An operating 110 MW power plant named Crescent Dunes is redesigned with biomimetic spiral, and performance is analyzed in this article. Additionally, five new hybrid layouts are proposed, and performance analysis is carried out. Among the proposed layout, Hybrid 4 layout, which has a biomimetic spiral pattern in the north region and radial staggered pattern in the south part of the central tower, outperforms all the layouts. Specifically, the optical efficiency increment for the Hybrid 4 layout is found to be 0.195% higher than the original layout. Moreover, to evaluate the layouts' performance in different weathers, the same seven layouts are studied in four zones in Bangladesh. While the order of the layouts varies slightly from zone to zone, the Hybrid 4 layout still emerges as superior.

Molten salts are typically used as energy storage media in concentrating solar power systems for their lower costs and environmental impact. This study aims to map and optimize the performance of parabolic trough concentrators (PTCs) working with molten salt-based nanofluids (MSNFs) as heat transfer media at high temperatures. The thermal, hydraulic, energetic, and exergetic performances were analyzed and optimized using a unique framework of Monte Carlo optical simulations, computational fluid dynamics, data-drive support vector regression, particle swarm optimization, and decision-making techniques. Three molten salts (Solar Salt, Hitec, and Hitec XL) and three nanoparticle types (Al2O3, CuO, and SiO2) were investigated in a broad range of volumetric concentrations (0.0–4.0%), operating Reynolds numbers (4 × 103 to 40 × 103), and temperatures (535–805 K). The results showed a maximum energy efficiency of 69.1%, achieved when using SiO2-Hitec nanofluid (1.0%) at a Reynolds number of 40 × 104 and temperature of 535 K. The maximum achieved exergy efficiency was 70.48%, obtained using pure Hitec at a Reynolds number of 40 × 104 and temperature of 535 K. The maximum possible enhancements in energy and exergy efficiencies in the covered range are 17.0 and 42.0%, respectively. The optimal combination of energy and exergy efficiencies are ∼73.1 and 69.0%, obtained using CuO-Hitec nanofluid at temperature, Reynolds number, and concentration of 535 K, 39912.98, and 0.019%, respectively. The optimum combination of percentage enhancements in energy and exergy efficiencies are 0.465 and 7.182%, respectively, which corresponds to CuO-Hitec nanofluid operating at 805 K, 32025.4, and 0.092%, respectively.

Solar energy 259, 257-276 (2023). doi:10.1016/j.solener.2023.05.008, Published by Elsevier Science, Amsterdam [u.a.]

settingsOrder Article Reprints Open AccessArticle Thermal Analysis of a Parabolic Trough Collectors System Coupled to an Organic Rankine Cycle and a Two-Tank Thermal Storage System: Case Study of Itajubá-MG Brazil by Gaylord Carrillo Caballero 1,2,Yulineth Cardenas Escorcia 3,Luis Sebastián Mendoza Castellanos 4,Ana Lisbeth Galindo Noguera 4,Osvaldo José Venturini 2,Electo Eduardo Silva Lora 2,Elkin I. Gutiérrez Velásquez 5 andAnibal Alviz Meza 6,*ORCID 1 Research Group en Energías Alternativas y Fluidos (EOLITO), Universidad Tecnológica de Bolívar (UTB), Cartagena 130002, Colombia 2 Excellence Group in Thermal Power and Distributed Generation-NEST, Institute of Mechanical Engineering, Universidade Federal de Itajubá, Itajubá 37500-000, Brazil 3 Research Group GIOPEN, Energy Department, Universidad de la Costa (CUC), Barranquilla 080016, Colombia 4 Research Group in Resources, Energy and Sustainability (GIRES), Faculty of Energy Engineering, Universidad Autónoma de Bucaramanga (UNAB), Bucaramanga 680008, Colombia 5 Faculty of Mechanic, Electronics and Biomedical Engineering, Universidad Antonio Nariño, Medellin 050005, Colombia 6 Research Group en Deterioro de Materiales, Transición Energética y Ciencia de datos DANT3, Facultad de Ingeniería, Arquitectura y Urbanismo, Universidad Señor de Sipán, Chiclayo 14002, Peru * Author to whom correspondence should be addressed. Energies 2022, 15(21), 8261; https://doi.org/10.3390/en15218261 Received: 5 October 2022 / Revised: 28 October 2022 / Accepted: 31 October 2022 / Published: 4 November 2022 Download Browse Figures Versions Notes Abstract This study examined an Organic Rankine Cycle powered by a parabolic trough collector and a two-tank thermal storage system based on the development of a mathematical model, for the conditions of the city of Itajubá in Brazil. First, geometrical optics and heat transfer models of the collector–receiver set were used to determine the thermal equilibrium of the solar thermal collector system and parameters such as the efficiency of the solar field, heat and optical losses, and thermal energy of the outlet fluid. Next, the thermal equilibrium of the Organic Rankine Cycle was found in order to establish its operational parameters. Finally, the behavior of the thermal storage system was analyzed through its modeling. Once the characterization of the storage system was completed, the integrated operation of the proposed system was evaluated. Given Itajubá’s weather conditions, the results indicate that an electricity generation system can be implemented with the Solel UVAC Cermet selective coating for the absorber tube, water as the heat transfer fluid, and R-245fa as the working fluid. Based on the solar irradiation profile (1 March 2019), the parabolic trough collectors provided 63.3% of the energy required by the Organic Rankine Cycle to generate 7.4 kW, while the thermal storage system provided 36.4% of the energy demanded by the power generation block. Additionally, the results demonstrate the main conclusions that the turbine’s efficiency was influenced by parameters such as rotational speed, which is affected by the turbine inlet temperature, which, in turn, depends on the behavior of the solar irradiation profile onsite.

Parabolic Trough Concentrators (PTC) and Linear Fresnel Concentrators (LFC) are widely used for solar thermal applications. LFC's were developed as an alternative to counter the high manufacturing cost of parabolic collectors. The manufacturing cost of LFC is lower but it either reduces the output power or is larger in size. A hybrid collector combining the beneficial features of both PTC and LFC, which is compact and efficient, is proposed in this paper. Discrete Linear Fresnel plates are pivoted with their midpoints lying on a parabola and the performance is compared with LFC and PTC. A mathematical model is developed to calculate the projected area of the hybrid solar collector. The optical performance is estimated, considering the shading, blocking, cosine effect and end loss of the mirrors and is compared with a similar sized PTC and LFC. The optical performance at 8 a.m. for a hybrid collector is 58% of a similar sized PTC. The optical performance ratio increases with time, reaching a maximum of 93% at noon and decreases thereafter reaching 58% by 4 p.m. The comparison with LFC shows that the hybrid collector performs better than LFC by 5% between 10 a.m. and 2p.m and only 2% when averaged over the day. This has been found to increase to about 3.5% with modifications in hybrid collector design. The results were also calculated by solar ray tracing using SolTrace and were found to be in good agreement with the proposed model.

The performance of solar trough collectors can be enhanced by optimizing the mirror profile. Accordingly, a method for optimizing the trough mirror profile is introduced in the present work. This method aims at enhancing the amount of reflected solar irradiance onto the receiver tube. Optimum profiles “Opt1” and “Opt2” were obtained by implementing multi-objective multi-dimensional optimization. Results show that the “Opt1” profile enhances the overall efficiency of the trough collector by 8.2% compared to an original parabolic trough collector (PTC). This performance improvement was also recorded at different trough angles. The trough depth was reduced by up to 89% for the “Opt1” profile. Therefore, analysis of the wind loads was performed for the PTC and the optimized profiles. This analysis shows that the “Opt1” and “Opt2” profiles have higher wind loads compared to the PTC whenever the wind is blowing across the trough backside. The “Opt1” profile and the PTC have the same wind loads at the local solar noon. The “Opt1” profile has lower wind loads compared to “Opt2” and the PTC whenever the wind is facing the trough front side. Accordingly, adding shields on the backside of the trough is recommended for investigation in a future work.

In this study, thermodynamic and thermoeconomic analyses of systems that produce electricity and heat through the use and storage of solar energy and near-surface geothermal sources are carried out. Three different configurations, which are the organic Rankine cycle (ORC), cogeneration system (CGN) and hybrid system (HYB), are coupled to the parabolic trough collector (PTC) system. The systems are named PTC-ORC, PTC-CGN and PTC-HYB are conducted. The reference system called PTC-ORC only produces electrical energy with parabolic trough collectors and it does not have a thermal energy storage system, whereas in PTC-CGN, in addition to the cogeneration of electricity and heat, thermal energy storage is also available. Finally, thermodynamic and economic analyses are conducted in the PTC-HYB with the assistance of near-surface geothermal energy, which is widely available in Turkey. In this study, the actual data of Ankara Kizilcahamam near-surface geothermal fields are taken as the heat source for the hybrid system. These facilities, each producing 1 MW of electricity, are first optimized with the help of parametric studies, and exergoeconomic analysis is performed with respect to optimum thermal conditions. The electricity production costs of PTC-ORC, PTC-CGN and PTC-HYB are found to be 0.257 $/kWh, 0.448 $/kWh and 0.401 $/kWh, respectively. The study demonstrates that thermal energy storage brings extra costs, while near-surface geothermal sources may help decrease energy costs from renewables.

Enhancing the thermal efficiency of parabolic solar collectors is still a challenging issue. In this study, two strategies including using nanofluid and a rotary turbulator are applied to ameliorat...

The field of concentrating photovoltaic-thermal (CPV-T) systems based on nanofluid spectral filtering has advanced significantly in the past decade. However, there is still a need to perform economic feasibility analyses for these systems. In this work, an assessment of the cost of implementation of CPV-T power plants using the spectral-splitting technique was performed. Three types of solar power plant were analyzed, including a purely thermal parabolic trough, a hybrid Si-based, and a hybrid GaAs-based power plant. The levelized cost of energy (LCOE) algorithm included inputs obtained from random variables to obtain LCOE values and energy generation for each type of power plant as a probability distribution. The results show that a purely thermal parabolic trough system has a minimum LCOE of 13.29 ¢/kWh at a solar multiple of 1.75, while the hybrid Si and hybrid GaAs power plants had a minimum LCOE of 17.83 ¢/kWh at a solar multiple of 2.5, and 14.50 ¢/kWh at a solar multiple of 3. The results in this work demonstrate that spectral-splitting CPV-T power plants can achieve energy costs comparable to conventional parabolic power plants depending on the solar multiple, solar cell material, and technical and financial variables.

Parabolic trough collector stands out as the most proven and widely adopted technology for concentrating solar power. A simple mathematical model based on dividing the trough’s aperture and the surface of the absorber into small segments is developed herein. The model is used to investigate the influence of the design and operational parameters on the distribution of the concentrated solar flux over. In this study, eight absorbers with different geometries are considered and the effect of the rim angle, absorber’s geometry, and operational mode on the distribution of the concentrated solar flux over their surfaces have been addressed. For all absorbers, it has been found that increasing the rim angle results in reducing the intensity of the concentrated solar flux with increase in its coverage area. The distribution of the concentrated solar flux over the surface of the parabolic shaped absorber (ABS.6) is found to be uniform over the portion of the surface located between its two rims. It has also been demonstrated that the operation under free absorber mode can help in redistributing the concentrated solar flux over the absorber surface resulting in a more uniform distribution compared to that over the surface of the fixed absorber. From the combined geometries of the investigated absorbers two optimal shapes are obtained and are found to perform much better than the circular absorber ABS.1.

This paper investigates overall performance of a small-scale electrolytic hydrogen production, using an Organic Rankine Cycle (ORC) driven by a parabolic trough collector (PTC) plant, under the Algerian Sahara climate. The evaluations of PTC plant and the thermodynamic analysis of the ORC are performed by SAM and EES software, respectively. These results are then used for hydrogen production calculations. Among three southern cities investigated, Ghardaia is most favorable site to implement the proposed system. For the ORC plant, eight alternative working fluids (butane, n-pentane, isopentane, benzene, toluene, R245fa, R123 and water), are considered for comparison. As results, the highest output power and plant efficiency are achieved with benzene during May to August with maximum power of 8.74 kW and cycle efficiency of 21.65% during July. The highest hydrogen production rate is achieved in July with 847 Nm3 using the high temperature water vapor electrolyzer and benzene as working fluid.

A system analysis of energy production was performed comparing the system of photovoltaic panels and parabolic trough collectors with a hybrid absorber. The paper presents new design of hPTC-CPV absorber. The analysis includes a comparison of the performance of both technologies in different irradiance conditions over the year. The technologies were compared for the same active surface hPTC-CPV and PV. The analysis was performed for a single-family house based on its demand for heat, electricity, and cooling. The calculations are intended to show to what extent an analyzed renewable technology can cover the demand for particular types of energy. The analysis was carried out to assess the legitimacy of using hybrid radiation absorbers in a temperate climate. Hybrid absorber studies were performed using CFD software. The results show that the proposed technology can compete with a PV system in terms of cooling and heat generation. Hybrid absorber covers 74.7% of heat demand for absorption cooling. PV panels with a heat pump cover 44.3% of the heat demand, PV panels with electric heaters 24.3% and hPTC-CPV absorbers 23.3%. The proposed technology cannot compete with PVs in terms of electricity production. Hybrid absorbers cover 8.2% when PVs 71.9% of electricity demand.

Solar energy is one of the emerging technologies and the use of concentrating power technology is increasing in solar power plants. Parabolic trough collector is a concentrating solar power technology that is situated in the open terrain and subjected to wind loads. The structural stability of these devices under such loads determines the ability to accurately concentrate the rays at the absorber tube, which affects the overall optical and thermal efficiencies. A detailed numerical analysis is carried out at different wind loads and design conditions. It is observed that for a change in velocity from 5 m/s to 25 m/s, slope deviations increase from 1.21 mrad to 3.11 mrad at the surface of the reflector exceeding the shape quality of the mirror panels. Higher yaw angles and pitch angles of 60° and 120° are observed to be decisive in the design of collectors. Roof-mounted collectors experience a 40% higher drag force than ground-mounted collectors at a 0° pitch angle. For the Aluminium trough, the slope deviation at the surface of the reflector is higher by 4.62% than glass. The study will be helpful for engineers and scientists in the design of the parabolic trough collectors.

The present study focuses on the energy, exergy, exergo-economic, and exergo-environmental analyses of the solar-assisted multi-generation system. The multi-generation system consists of parabolic trough solar collector, regenerative power plant, double-effect absorption chiller system, proton exchange membrane electrolyzer, and multi-stage flash desalination plant. In the regenerative power plant, liquid petroleum gas (LPG) based boiler is implemented. The propane (C3H8) is used as the fuel in the boiler combustion chamber. The thermal and exergetic efficiencies of the power cycle are observed to be 41.08% and 23.26%, respectively. The electrical power of 1.384 MW is produced by the low-pressure turbine. Whereas, the thermal COP and exergetic COP are observed and maintained in the range of 1.28 to 0.22, respectively. The liquid hydrogen is produced by the PEM electrolyzer with the thermal and exergetic efficiencies of 60.83% and 64.65%, respectively. Furthermore, the exergo-economics and exergo-environmental analyses have also been conducted and all the parameters have been analyzed and concluded through graphs and tables.

CO2 based power and refrigeration cycles have been developed and analyzed in different existing studies. However, the development of a CO2 based comprehensive energy system and its performance analysis have not been considered. In this study, the integration of a CO2 based solar parabolic trough collector system, a supercritical CO2 power cycle, a transcritical CO2 power cycle, and a CO2 based cascade refrigeration system for hydrogen production and multigeneration purpose is analyzed thermodynamically. This study aims to analyze and compare the difference in the thermodynamic performance of comprehensive energy systems when CO2 is used as the working fluid in all the cycles with a system that uses other working fluids. Therefore, two comprehensive energy systems with the same number of subsystems are designed to justify the comparison. The second comprehensive energy system uses liquid potassium instead of CO2 as a working fluid in the solar parabolic trough collector and a steam cycle is used to replace the transcritical CO2 power cycle. Results of the energy and exergy performance analysis of two comprehensive energy systems showed that the two systems can be used for the multigeneration purpose. However, the use of a steam cycle and potassium-based solar parabolic trough collector increases the comprehensive energy systems’ overall energy and exergy efficiency by 41.9% and 26.7% respectively. Also, the use of liquid potassium as working fluid in the parabolic trough collectors increases the absorbed solar energy input by 419 kW and 2100 kW thereby resulting in a 23% and 90.7% increase in energetic and exergetic efficiency respectively. The carbon emission reduction potential of the two comprehensive energy systems modelled in this study is also analyzed.

The objective of this paper is the parametric analysis of a solar-fed trigeneration system ideal for the building sector that produces useful heat, electricity and cooling. The examined unit is driven by 100 m2 of parabolic trough collectors which are combined with a sensible storage tank with thermal oil. An organic Rankine cycle is fed by solar useful heat production and it produces electricity while a part of its power drives a vapor compression cycle with R290. Heating is also produced by separate heat exchangers in the solar loop. The parametric analysis is conducted in steady-state conditions with a developed model in Engineering Equation Solver. The examined parameters are the following: superheating degree in the turbine inlet, cooling production, heating production, solar beam irradiation intense, sun angle, pressure level in the turbine inlet and heat source temperature level. For the nominal scenario of 10 kW cooling production at 5°C and 10 kW heating production at 60°C, the system produces 6.14 kW electricity, while the exergy and energy efficiencies are found 12.14% and 37.34% respectively. Assuming that the system operates 2500 h yearly, the simple payback period of the investment is calculated at 8.5 years. The maximum examined values for both heating and cooling production are at 20 kW.

The objective of this paper is to investigate the theoretical performance of Parabolic Trough Collector (PTC) using various nanofluids. The theoretical performances are calculated for Al 2 O 3 , graphite, magnetite, SWCNH, CuO, SiO 2 , MWCNT, TiO 2 , Fe 2 O 3 , and ZnO in water nanofluids. The heat transfer equations, thermodynamic properties of nanofluid and pumping power are utilised for the development of novel thermal model. The theoretical thermal efficiency of the PTC is calculated, and the economic viability of the technology is predicted for a range of nanofluid concentration. The results showed that the thermal conductivity increases with the concentration of nanoparticles in the base fluid. Magnetite nanofluid showed the highest thermal efficiency, followed by CuO, MWCNT, ZnO, SWCNH, TiO 2 , Fe 2 O 3 , Al 2 O 3 , graphite, and SiO 2 , respectively. The study reveals that MWCNT at 0.4% concentration is the best-suited nanofluid considering thermal gain and pumping power. Most of the nanofluids achieved optimum efficiency at 0.4% concentration. The influence of mass flow rate on thermal efficiency is evaluated. When the mass flow rate increased from 70 Kg/hr to 90Kg/hr, a 10%-20% efficiency increase is observed. Dispersing nanofluids reduces the levelized cost of energy of large-scale power plants. These findings add to the knowledge of the scientific community aimed explicitly at solar thermal energy technology. The report can also be used as a base to pursue solar thermal projects on an economic basis.

The maximum concentration ratio of the commercial parabolic trough collectors is limited to 42% of the theoretical limit of concentration. Recently, the secondary flat reflector geometry has been p...

This study presents a novel mechanical technique for solar concentration system that integrated with single-axis tracking mechanism without needs of electricity, electronic components, nor special materials. The presented mechanism aimed basically the small-sized solar Parabolic Trough Collector (PTC) to spread it in fields that limited by the disadvantage of the commercial tacking systems. The presented tracking mechanism utilizes the wind energy at the night time by stored-in potential energy to be its actuated energy. In addition, the same wind energy system could a circulate the Heat Transfer Fluid (HTF) along the day hours with automatically shifting. A 3-D model has been designed and a practical model has been fabricated and constructed from cheap materials then tested experimentally. The results showed that the accuracy of the tracking mechanism has maximum deviation at the early and lately hours of the day. It was in the range of (−3.36°–1.65°) with arithmetic average less than 0.5° and standard deviation less than 0.75° for its absolute values along the year. Experimental thermal results of small PTC with 91 cm width, 148 cm length and one-inch absorber tube showed 185.5 C stagnation temperature of a synthetic oil in fall season weather.

This study investigates the performance enhancement of parabolic trough concentrators (PTCs) with transparent insulation material shell (TIMS) of different diameters and thicknesses integrated into evacuated and non-evacuated heat collection elements (HCEs). The results show that non-evacuated TIMS-HCEs have higher energy and exergy efficiencies by up to 62.4 and 63.2%, compared to conventional evacuated HCEs, and by up to 109.2 and 110.9%, compared to conventional non-evacuated HCEs. At high flow rates and low fluid temperatures, the energetic performance of a conventional evacuated HCE is only 6.3% higher than that of the modified non-evacuated one. The modified design also enhances the circumferential temperature uniformity and shows a marginal drop in efficiency when the vacuum is lost. By simulating the PTC performance during four typical days, and without vacuum, the proposed design increased the daily useful heat gain by up to 1.36 and 5.64 kWh, compared to conventional evacuated and non-evacuated HCEs, respectively. Hence, it is proposed as a low-tech alternative to HCE evacuation and as a method of boosting the performance of PTCs operating at low flow rates and high temperatures.

In this work, a novel parabolic trough receiver (NPTR) with an inner tube and wing-like fringe was proposed to improve heat-collecting efficiency as well as provide different grades of thermal energy. Thermal oil and water, which flow respectively in absorber and the inner tube, are selected as high and low temperature heat transfer fluids. A three-dimensional computational fluid dynamics model was developed to investigate the performance of the NPTR. Effects of geometrical parameter and thermal conductivity of inner tube on the performance of NPTR were studied in details. Based on the results, the NPTR with β = 180° is recommended as the suggested design. Moreover, performance of the suggested design under different direct normal irradiances (300–1000 W/m2) and inlet temperature of oil (400–650 K) were evaluated. Compared to the conventional parabolic trough receiver, the heat loss of NPTR is effectively reduced by 33.1–50.1%, and the overall efficiency can be improved by 0.61%–7.67%. Moreover, the proportions of oil and water heat gains in the total input solar energy are ranged in −18.8–63.5% and 8.39–77.6%, and the temperature gains of oil and water are ranged in −1.4–19.5 K and 5.4–18.8 K, respectively.

The enhancement of yield of solar still (SS) is viewed as very significant due to the production of the potable water. It is also considered as uncomplicated device for desalination. There is also ...

The developmental tendency of parabolic trough collector (PTC) is larger aperture area for energy harvest and novel optical design for higher solar concentration. Larger aperture faces a higher demand in tracking accuracy and lower tolerances with respect to wind loads, quality of mirrors, control, and mounting imprecisions. With the increase of reflection angle, the divergence size of concentrated focal spot gets enlarged on receiving surface, forming a Gaussian distribution. Receiving more energy and making best use of the concentrated solar power have become a key problem. In current study, a novel trough free-form solar concentrator (TFFC) has been developed by extending the aperture size with the aid of freeform optics and combined PV/thermal utilization. The structure model is composed by traditional parabolic trough with thermal tube, and extended freeform reflector with solar panel in slope configuration. The free-form surface is generated by geometric construction method for the sake of uniform heat flux distribution. The optical characteristics are validated by ray tracing method. The advantages will be revealed by compared with traditional system. The sensitivity analysis and error factors would be discussed as well. The initial results are promising and significant for the enhancement of trough type solar concentrator systems.

In common parabolic trough solar collectors (PTC), solar irradiation is concentrated at the bottom of the absorber tube, causing high surface temperatures, thermal stresses, and deflections with subsequent damages and costs. Also, the performance improvement of PTCs is always of significant importance. The new idea of rotating the absorber tube is proposed, and its effects on the PTC performance are studied experimentally. The effects of the working fluid flow rate (Re number) and the rotational velocity of the absorber tube (Ta number) on the energy characteristics of the PTC are analyzed. Results indicate that the optimal selection of the rotational speed makes it possible to reduce and control the temperature of the absorber by about 60% reduction in the fluid-tube temperature difference, and 15% reduction in the maximum surface temperature. Furthermore, about 17% enhancement in the efficiency of the PTC is attained. The share of the natural and both the rotational and mass flow forced convection forces in the total heat transfer is analyzed through Gr, Re, Ta, and a convection evaluation parameter (CEP). Ta/Re ratio and CEP provide valuable information such that, CEP T a / R e ≈ 0.5 led to the highest efficiency (average and maximum efficiencies of 30% and 87% respectively).

An improved evacuated absorber tube (AT) design consisting of a semi-circular tube is proposed for large-aperture parabolic trough concentrator. The absorber tube also contains a flat-plate radiation shield in the vacuum part of the tube in the glass cover. To enhance the heat transfer in the AT, different fins geometries added to the bottom of the AT were analyzed here. Compared to an AT without fins, the thermal efficiency of the tube could be increased from 75.7% to 76.9% with a short and thick fin and to 77.3% with a long and thin fin in the flow velocity range of 0.4–1.5 m/s. The long and thin finned AT shows better enhancement of heat transfer, but the heat transfer performance factor also accounting for frictional losses is higher for short and thick fin. Simultaneously, increasing the number of long and thin fins in the AT would not improve much the heat transfer performance.

The temperature limitation of thermal oil which limits the overall efficiency of a thermodynamic cycle has propelled the study of the usage of supercritical fluid in parabolic trough solar collector (PTSC) due to its ability to operate at higher temperature levels. s C 0 2 is the most popular supercritical fluid currently studied in PTSC, but there are some other supercritical fluids have been used in industrial applications yet rarely studied in PTSC. In this research, the performance of three different supercritical fluids namely, water (s H 2 O ) , nitrogen (s N 2 ) , Sulphur hexafluoride (s S F 6 ) along with carbon dioxide ( s C O 2 ) was studied and compared. A 1-D mathematical model was developed, validated, and it was solved by the commercial software EES. The results showed that the energetic performance of water is superior to the rest of the fluids at common inlet temperatures with s N 2 showing comparable performance to s C O 2 and s S F 6 showing consistently weaker performance than the rest. The exergetic performance of these fluids showed that s H 2 O and s S F 6 are promising alternatives to s C O 2 . All fluids showed maximum exergetic efficiency at an inlet temperature of 750K with the respective maximum for s H 2 O , sS F 6 , s C O 2 and s N 2 of 46.46%, 46.24%, 46.11% and 45.76%. Comparison of these supercritical fluids to Therminol VP-1 and molten salts also showed promising potential. H 2 O is the best supercritical fluid for usage in thermal storage at 650K where it has thermal storage energy density (TSED) of around 165% higher than the highest value of molten salt’s TSED.

Recently, supercritical carbon dioxide, S-CO2, has been suggested for utilization as the working fluid in solar thermal power plants. Replacing current working fluids with S-CO2, however, is not a straightforward task. This work numerically investigates the heat transfer and flow filed in a parabolic trough solar collector which carries S-CO2. A full-scale three-dimensional model of the parabolic trough is developed and analyzed using the Star CCM + software. The variation of carbon dioxide’s thermophysical properties inside the receiver tube is considered. The computational model is validated against a set of experimental data published by Sandia National Laboratories with no more than a 2.81% error margin. The numerical experiment is carried out at five different times during a typical summer day in Albuquerque, NM. Numerical results confirm that in all cases, heat loss from the upper half of the receiver tube is more than the absorbed solar incidence on that side. At noon, when the absorbed heat flux on the lower surface of the receiver tube reaches its maximum at 29810 W/m2, the net heat loss flux from the upper half of the receiver tube reaches 2622 W/m2. Consequently, the heat transfer from the upper half of the receiver tube unfavorably impacts the thermal efficiency of the parabolic trough. Additionally, while from 8 AM to 12 PM thermal efficiency drops less than 2.4%, the S-CO2 temperature increment grows over 182%. A reverse trend occurs from noon to 4 PM, mainly due to the change in the available solar incidence.