Parabolic Trough Concentrator System Research Articles

Performance comparison of a solar parabolic trough concentrator using different shapes of linear cavity receiver

This study presents a numerical investigation of a solar Parabolic Trough Concentrator (PTC) with various Linear Cavity Receivers (LCRs). A linear trapezoidal cavity receiver was simulated and analyzed optically and thermally in the PTC system. The performance of the linear trapezoidal cavity receiver was assessed at two different angles: 25° and 55°. Optical and thermal simulations were conducted on a PTC system with a novel linear wounded tubular trapezoidal LCR. Subsequently, the optical and thermal performance of the PTC system was compared with alternative LCR shapes, namely cubical, V-shaped, trapezoidal 25°, and trapezoidal 55°. Additional contribution of the present study is to conduct energy and exergy analyses on the optimized solar PTC system employing a soybean oil-based-MXene nanofluid with varying concentrations (0 %, 0.025 %, 0.075 %, and 0.125 % weight). The findings indicate that all LCRs exhibit optimal cavity-absorbed heat flux and optical efficiency when aligned with the focal line. Moreover, the cubical and trapezoidal cavity receivers, when equipped with the ideal aperture width, demonstrate the highest and lowest performance, respectively. The most favorable exergy performance is achieved by employing the nanofluid concentration of 0.075 % weight at an inlet temperature of 55 °C at about 4 %. Also, the thermal efficiency of the solar system was calculated as about 82 % with the application of the nanofluid concentration of 0.075 % weight at an inlet temperature of 25 °C. The research findings offer valuable insights into enhancing the performance of the solar thermal system to generate more power for the implementation of the 7th development plan in Iran.

A Novel Design of Parabolic Trough Solar Collector's Absorber Tube

Abstract This paper proposes an investigation of a novel design of receiver absorber tube (circular-trapezoidal shaped) for PTC (Parabolic Trough Concentrator) system aiming at catching a part of the lost (reflected) solar rays due to effects related to the incidence angle deviation, and thus improving the PTC's thermal performance. Although they are always present in PTC, the effects of the deviation angle are often not considered in the literature. These effects are considered here in view of presenting a better and more useful focal area, the optimal circular-trapezoidal absorber tube shape being determined according to the maximal limit of the deviation angle that allows catching the maximum amount of solar rays. The corresponding model is established considering it as a two-dimensional problem and the derived deviation angle coefficient compared to that obtained for a traditional circular shaped tube. Moreover, the energy balance model is adapted to simulate the thermal efficiency of the considered tubes as a function of the deviation angle with some assumptions. The obtained results prove that from a deviation angle value of 0.1 degrees, the gain in efficiency becomes more significant; it can reach 5 % and even be higher for a deviation angle value of 0.5 degrees. Finally, Comsol Multiphysics software package was used to determine the pressure drops, temperature and velocity field distributions, considering a deviation angle value of 0.2 degrees. The results confirm that the proposed tube absorbs more heat than the traditional one.

Enhancing thermal performance and sustainability parabolic trough concentrator systems in Djelfa's solar-integrated urban design

In this study, the coldest days of 2022 in the Djelfa region, Algeria, were determined using astronomical and climatic data. The timing of sunrise, sunset, and duration of sunlight, as well as changes in solar radiation intensity and air temperature, were analyzed. By converting solar radiation into heat and solving differential equations, the study examined water exit temperature, thermal energy, and total yield as outputs of a renewable energy converter. The effect of different glass coverings on these outputs was also investigated. The coldest day in 2022 was found to be the first day of January, with nine hours and 43 minutes of sunlight, a maximum solar radiation intensity of 670.34 MW/m?, and a maximum air temperature of 16.9?C. The outputs of the solar center followed a parabolic pattern for the first two parameters and increased over time for the remaining outputs, regardless of the glass type. However, using glass with a high emission coefficient, such as clear monochromatic glass, resulted in the highest values for the outputs: 52.57?C, 7.5 kW, 162 MW, and 70.62%. By understanding solar energy conversion and thermal behavior, the study contributes to energy-efficient designs and renewable integration, aiding in sustainable urban development. Findings can inform decision-makers in optimizing material selection, promoting resilient infrastructure, and advancing sustainable practices for a low-carbon future.

Optical, thermal and thermo-mechanical model for a larger-aperture parabolic trough concentrator system consisting of a novel flat secondary reflector and an improved absorber tube

Using a larger-aperture parabolic trough concentrator can reduce cost and improve cycle efficiency. At present, the maximum output temperature of the typical parabolic trough concentrator systems is lower than the set 580 °C. Here a novel flat reflector was incorporated into the absorber tube to improve the intercept factor and optical efficiency and hence the overall performance. At the same time, the optimal diameter of the collector tube was also researched to meet the outlet temperature exceeding the set 580 °C and the absorber tube’s maximum temperature below 600 °C. A large-aperture parabolic trough concentrator (8 m aperture wide with 80° half rim-angle) is used as a case to demonstrate the effect of a flat reflector and advantages of the optimal absorber tube. Results obtained through simulations show that, in the large-aperture parabolic trough concentrator system with the flat reflector, the optimal diameter of the absorber tube was 70 mm for this design reaching 75% optical efficiency and 60.8% thermal efficiency at DNI = 1000 W/m2 and 53% daily average thermal efficiency for DNI = 400–1000 W/m2. Through adding a flat reflector, the optical efficiency and the uniformity were increased by 4–12% and 2–22% respectively, but the benefit gradually decreases with increasing the absorber tube diameter. To meet the requirement of outlet temperature more than 580 °C and absorber tube’s maximum temperature below 600 °C and reduce the thermal strain, a scheme of adjusting flow rate was incorporated.

Optical performance of a hybrid compound parabolic concentrator and parabolic trough concentrator system for dual concentration

This work proposes a hybrid compound parabolic concentrator and parabolic trough concentrator (CPC/PTC) system for concentrator photovoltaic/thermal (CPV/T) and hybrid concentrator photovoltaic/thermal-thermoelectric generator (CPVT-TEG) applications. The geometrical design and optical analysis of the novel hybrid CPC/PTC system are discussed in the present study. Ray-tracing models were used to identify the different variables that influence the optical efficiency of both CPC and PTC. The concentration ratio (CR) of PTC in the hybrid CPC/PTC system is evaluated and compared with the standard PTC concentration ratio for various rim angles ranging from 15° to 75°. The results revealed that the loss in PTC concentration due to the CPC’s shadow on the hybrid CPC/PTC system is reduced when the aperture width of the PTC is increased. The maximum optical efficiency of the hybrid CPC/PTC system for 0° incident angle is ~ 73% which is ~ 6.35% higher than standard PTC. Finally, the proposed hybrid CPC/PTC system’s overall optical efficiency is evaluated under various tracking modes for equinox, summer solstice, and winter solstice. The results imply that the dual-axis tracking CPC/PTC system achieves a constant optical efficiency of ~ 70%.

Optimizing research on large-aperture parabolic trough condenser using two kinds of absorber tubes with reflector at 500 °C

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.

4E assessment of power generation systems for a mobile house in emergency condition using solar energy: a case study

In this study, a solar parabolic trough concentrator (PTC) was evaluated as a heat source of a power generation system based on energy (E1), exergy (E2), environmental (E3), and economic (E4) analyses. Various configurations of power generation systems were investigated, including the solar SRC (SRC) and solar ORC (ORC). Water and R113 were used as heat transfer fluids of SRC and ORC system, respectively. It should be mentioned that the proposed solar systems were evaluated for providing the required power of a mobile house in an emergency condition such as an earthquake that was happened in Kermanshah, Iran, in 2016 with many homeless people. The PTC system was optically and thermally investigated based on sensitivity analysis. The optimized PTC system was assumed as a heat source of the RC with two various configurations for power generation. Then, the solar RC systems were investigated based on 4E analyses for providing the power of the mobile house based on various numbers of solar RC units. It was concluded that the solar SRC system could be recommended for achieving the highest 4E performance. The highest value of its energy efficiency was found at 24.60% and of his exergy at 26.37%. On the other hand, the ORC system has energy and exergy efficiencies at 17.64% and 18.91%, respectively, which are significantly lower than the efficiencies of the SRC system. The optimum heat source temperature for the SRC system is found at 650 K, while for the ORC system at 499 K. Moreover, the best economic performance was found with the SRC system with a payback period of 7.47 years. Finally, the CO2 mitigated per annum ( $$\varphi_{{{\mathrm{CO}}_{2} }}$$ ) was estimated at 5.29 (tones year−1), and the carbon credit ( $$Z_{{{\mathrm{CO}}_{2} }}$$ ) was calculated equal to 76.71 ($ year−1).

Improving the performance of large-aperture parabolic trough solar concentrator using semi-circular absorber tube with external fin and flat-plate radiation shield

Abstract An improved absorber tube (AT) design consisting of a semi-circular and an external flat fin with a flat-plate radiation shield inside an evacuated annulus is proposed for large aperture parabolic trough concentrator (PTC) systems. In the present design, the AT’s semi-circular part absorbs the most sun rays. The other rays originally absorbed by the AT’s upper part is intercepted by the external two fins. The flat-plate radiation shield reflects the external radiation energy from the AT’s upper half back to the AT. The trough has an aperture of 8m and an 80° half rim angle. The AT consists of a semicircle with a diameter of 100 mm and outer fins. The optical and thermal efficiency of this new design was up to 83.3% and 80.3%, respectively. The optical and thermal efficiency was 8%-units higher than that of the traditional optimal design. The maximum temperature always appears at the edge of the fin, which is up to 50 °C higher than that of the heat transfer fluid (HTF) at 0.5 m/s, which was the optimal fluid rate for the new design. The fins also contribute to the efficiency of the PTC: 6.5% to the optical and over 3.5% to the thermal efficiency. The improved AT design will help to plan more effective PTC systems.

Study of PTC System with Rectangular Cavity Receiver with Different Receiver Tube Shapes Using Oil, Water and Air

Today, application of cavity receivers in solar concentrator systems is suggested as an interesting and novelty research subject for increasing thermal performance. In this research, a parabolic trough concentrator (PTC) with a rectangular cavity receiver was energetically investigated. The cavity receiver was studied with smooth and corrugated tubes. Different solar heat transfer fluids were considered, including water, air, and thermal oil. The effect of different operational parameters, as well as structural parameters, was investigated. The results showed that the linear rectangular cavity receiver with corrugated tube showed higher amounts of the absorbed heat and energy performance compared to the smooth tube as the cavity tube. Thermal performance of the rectangular cavity was improved using the application of water as the solar heat transfer fluid, which was followed by thermal oil and, finally, air, as the solar heat transfer fluid. Finally, it could be recommended that the rectangular cavity receiver with smooth tube using air as the solar heat transfer fluid is more appropriate for coupling this system with a Bryton cycle, whereas the rectangular cavity receiver with the corrugated tube using water or oil as the solar heat transfer fluid is recommended for achieving higher outlet temperature of the heat transfer fluid.

Improving the performance of a 2-stage large aperture parabolic trough solar concentrator using a secondary reflector designed by adaptive method

In this study, the efficiency of a large aperture 2-stage parabolic trough concentrator (PTC) is improved using an innovative design method for the secondary reflector (SR). The design method is based on an adaptive approach in which the SR is step-wise optimized to maximally reflect back to the absorber tube (AT) the part of solar radiation reflected by the primary reflector (PR) but not captured by the AT. The adaptive design method results in a SR design which consists of several parabolas with different focal lengths, each having a focus which lies in the focus of the PR. This ensures that the originally unabsorbed solar radiation will now hit the surface of AT. The optical efficiency of the PTC could be increased by 5.2% and thermal efficiency by 4.9%, respectively, compared to a case without optimized SR. In addition, the uniformity of the solar radiation flux on the AT’s outer wall could be doubled, its temperature was more even. The new adaptive design approach of the SR could help to better optimize PTC systems.

Prediction of captured solar energy for different orientations and tracking modes of a PTC system: Technical feasibility study (Case study: South eastern of MOROCCO)

In this paper, a technical feasibility study on a parabolic trough concentrator (PTC) system for predicting the captured energy in different orientations and tracking modes has been investigated. Thus, the potential of captured solar radiation by a PTC has been estimated by combining simulations and different mathematical models, atmospheric parameters and optical as well as geometric characteristics of the PTC under climate conditions of Errachidia region in south eastern of Morocco (latitude 31.93° N, longitude −4.53° E, altitude 1039 m). Moreover, simulations study for an annual period was carried out using Matlab and TRNSYS for different orientations and tracking modes for the investigated PTC system. From the simulations result we noticed a higher mean daily PTC thermal efficiency of about 28.2% during summer solstice for a full tracking. However, the thermal efficiency of the PTC remains about 27.5% during spring equinox for full tracking and inclined N-S axis (E-W tracking), while it is around 24.2% for full tracking and polar axis (E-W tracking) and about 22.5% for full tracking during autumn equinox and winter solstice, respectively. These first results may enable to forecast the region potential and the feasibility of the investigated system for various orientations and tracking modes for each annual period. In addition, the simulation results clearly show that the studied region remains a suitable location to install PTC systems.

A novel solar concentrating system based on a fixed cylindrical reflector and tracking receiver

Abstract The performance of a novel solar energy concentrating system consisting of a cylindrical mirror placed in a stationary position and a receiver tracking system is investigated. Via a computational tool based on the ray-tracing method, the sensitivity of the geometric concentration ratio, rim angle, shadow angle, incidence angle and hourly insolation level to the optical performance of the concentrator are evaluated. The simulation includes a model of solar concentrating system based on the approximation of the optical behavior of a cylindrical reflector. In fact, the optical efficiency of the solar concentrator system is examined. The results prove that the maximum of the optical efficiency is achieved for 20 × geometric concentration ratio and 80°-rim angle. Moreover, the concentrated solar density and the Local Concentration Ratio (LCR) distribution along the tracked receiver tube are analyzed and compared to those obtained by the classical one-axis tracked parabolic trough concentrator system.

Modeling and optimization of a solar parabolic trough concentrator system using inverse artificial neural network

In this paper, an artificial neural network inverse (ANNi) model is applied to optimize the thermal performance (η) of parabolic trough concentrators. A feedforward neural network architecture is trained using an experimental database from parabolic trough concentrators operations. Rim angle (φr), inlet (Tin) and outlet (Tout) fluid temperatures, ambient temperature (Ta), water flow (Fw), direct solar radiation (Gb), and the wind velocity (Vw) were used as main input variables within the neural network model to estimate the thermal performance with a correlation coefficient of R2 = 0.9996 between experimental and simulated values. The sensitivity analysis is carried out to verify the effect of all input variables. The optimal operation conditions of parabolic trough concentrators are established using artificial neural network inverse modeling (ANNi) to achieve optimal operation conditions of parabolic trough concentrators. The results indicated that ANNi is a feasible tool for Parabolic Trough Concentrators optimization.

Performance Prediction of Solar Thermal Parabolic Trough Concentrator System (STPTCS) by Enhancement of Heat Transfer

Performance Prediction of Solar Thermal Parabolic Trough Concentrator System (STPTCS) by Enhancement of Heat Transfer

Design Point for Predicting Year-Round Performance of Solar Parabolic Trough Concentrator Systems

Thermal efficiencies of the solar field of two different parabolic trough concentrator (PTC) systems are evaluated for a variety of operating conditions and geographical locations, using a detailed 3D heat transfer model. Results calculated at specific design points are compared to yearly average efficiencies determined using measured direct normal solar irradiance (DNI) data as well as an empirical correlation for DNI. It is shown that the most common choices of operating conditions at which solar field performance is evaluated, such as the equinox or the summer solstice, are inadequate for predicting the yearly average efficiency of the solar field. For a specific system and location, the different design point efficiencies vary significantly and differ by as much as 11.5% from the actual yearly average values. An alternative simple method is presented of determining a representative operating condition for solar fields through weighted averages of the incident solar radiation. For all tested PTC systems and locations, the efficiency of the solar field at the representative operating condition lies within 0.3% of the yearly average efficiency. Thus, with this procedure, it is possible to accurately predict year-round performance of PTC systems using a single design point, while saving computational effort. The importance of the design point is illustrated by an optimization study of the absorber tube diameter, where different choices of operating conditions result in different predicted optimum absorber diameters.

Computer Modelling of Hybrid Solar Parabolic Trough Concentrator Systems—Electrical Part

This paper is to develop a mathematical model for hybrid solar parabolic trough concentrator (PTC) systems. The model is for estimation of energy outputs, losses and efficiencies of various parts of the system which operates under different climate condition, diverse configurations and a range of loading conditions. Automated system optimization can be quickly obtained by trying numerous different system configurations. In hybrid PTC system, photovoltaic cells are also installed on the receiver pipes. Solar energy is directly converted to electricity by photovoltaic cells. The working fluid circulating in the receiver pipes is for solar thermal purpose as well as to cool down the temperature of solar cells. The overall yield of the system is increased and therefore capital cost is reduced. A detailed analytical model simulating a hybrid PTC system has been developed by modelling and integrating sub-components into one model and a simulation software has been developed. The software is a valuable design tools for engineers whenever they are designing hybrid PTC systems, which are likely feasible in application to densely populated city with sub-tropical climatic conditions in southern part of China. System performance has been tested with a set of initial parameters and preliminary results have been produced.

Thermal stress analysis of eccentric tube receiver using concentrated solar radiation

In the parabolic trough concentrator with tube receiver system, the heat transfer fluid flowing through the tube receiver can induce high thermal stress and deflection. In this study, the eccentric tube receiver is introduced with the aim to reduce the thermal stresses of tube receiver. The ray–thermal–structural sequential coupled numerical analyses are adopted to obtain the concentrated heat flux distributions, temperature distributions and thermal stress fields of both the eccentric and concentric tube receivers. During the sequential coupled numerical analyses, the concentrated heat flux distribution on the bottom half periphery of tube receiver is obtained by Monte-Carlo ray tracing method, and the fitting function method is introduced for the calculated heat flux distribution transformation from the Monte-Carlo ray tracing model to the CFD analysis model. The temperature distributions and thermal stress fields are obtained by the CFD and FEA analyses, respectively. The effects of eccentricity and oriented angle variation on the thermal stresses of eccentric tube receiver are also investigated. It is recommended to adopt the eccentric tube receiver with optimum eccentricity and 90° oriented angle as tube receiver for the parabolic trough concentrator system to reduce the thermal stresses.