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One of the existing and commonly used solar energy harvesting devices is the parabolic trough solar collector (PTSC). Because of their ability to operate in low and medium temperatures, parabolic trough concentrators are widely used in power generation plants and industrial process heating applications. Therefore, the investigation of how different operating conditions affect these devices’ overall efficiency has received a great deal of attention in the recent decade. This study aims to enhance the thermal performance of the PTSC and reduce the system cost.

In the novel configuration, a noncirculated nanofluid absorbs solar radiation through a glass wall. The base fluid was synthetic oil (5W30), and the nanoparticles used were copper oxide. The heat captured is immediately absorbed by the water circulating inside the copper tube immersed in the nanofluid. ANSYS FLUENT 15.0 was used for carrying out computational fluid dynamics simulations for two models of single and triple copper tubes. The experimental results obtained from a test rig constructed for this purpose were compared with the numerical outcomes of the single copper tube model.

The findings of the simulation demonstrated that performance was superior for the single copper tube model over the triple copper tube model. The numerical findings of the single copper tube model were compared with the experimental results. The numerical and experimental results differed from 3.17% to 5.6%. Investigations were carried out to study the effects of varying the volumetric flow rate of (20, 40, 60 and 80 L/h) and water inlet temperatures of (300, 315 and 330 K) on the effectiveness and performance of the newly developed model. Additionally, two nanofluid volume fractions of 0.05% and 0.075% were used for investigating their effect on the performance of the novel configuration. According to the findings, the highest thermal efficiency of 55.31% was recorded at 0.075% concentration and 80 L/h volume flow rate.

In this study, a novel direct absorption solar collector configuration using a noncirculated nanofluid was designed to enhance the thermal efficiency of PTSC. This new approach makes it possible to boost the thermal performance of the PTSC and lower the system’s cost.

This paper aims to present the numerical models and experimental outcomes pertain to the performance of the parabolic dish concentrator system with a modified cavity-type receiver (hemispherical-shaped).

The numerical models were evolved based on two types of boundary conditions; isothermal receiver surface and non-isothermal receiver surface. For validation of the numerical models with experimental results, three statistical terms were used: mean of absolute deviation, R² and root mean square error.

The thermal efficiency of the receiver values obtained using the numerical model with a non-isothermal receiver surface found agreeing well with experimental results. The numerical model with non-isothermal surface boundary condition exhibited more accurate results as compared to that with isothermal surface boundary condition. The receiver heat loss analysis based on the experimental outcomes is also carried out to estimate the contributions of various modes of heat transfer. The losses by radiation, convection and conduction contribute about 27.47%, 70.89% and 1.83%, in the total receiver loss, respectively.

An empirical correlation based on experimental data is also presented to anticipate the effect of studied parameters on the receiver collection efficiency. The anticipations may help to adopt the technology for practical use.

The developed models would help to design and anticipating the performance of the dish concentrator system with a modified cavity receiver that may be used for applications e.g. power generation, water heating, air-conditioning, solar cooking, solar drying, energy storage, etc.

The originality of this manuscript comprising presenting a differential-mathematical analysis/modeling of hemispherical shaped modified cavity receiver with non-uniform surface temperature boundary condition. It can estimate the variation of temperature of heat transfer fluid (water) along with the receiver height, by taking into account the receiver cavity losses by means of radiation and convection modes. The model also considers the radiative heat exchange among the internal ring-surface elements of the cavity.

Geometric structure error of parabolic trough concentrator (PTC) frame affects the installation accuracy of mirrors and absorber tubes and thus decreases the solar energy concentrating efficiency. Until now, there is no effective method to instruct the assembly and regulation of PTC frames. This paper aims to propose a vision guided method for fast and accurate regulation of mirror and absorber supports to improve the geometric quality of PTC frames.

The PTC frame support regulating system consists of a general-purpose online photogrammetry system, frame support measurement adaptors and data analyzing software. First, the positions and angles of all the supports are measured in real time by the online photogrammetric system. Then, the measured positions and angles are aligned to the design reference frame through the transformation calculated by an absorber position constrained nonlinear optimization so as to get the geometric errors and regulating amounts. Finally, a graduated pseudo-color-based visualization method is proposed to assist the manual or automated regulation of PTC frame supports in site.

The proposed method does not need to construct a reference system nor specify the rotation attitude of the PTC frame, and it is capable of conducting efficient and accurate regulation on PTC frame assembly line. The method is applied to manual regulation of a light type PTC frame structure. After regulation, the maximum position and angle errors of supports are reduced to less than 0.15 mm and 0.15° respectively and the intercept factor is increased to 97%, which meets the requirement for a qualified PTC concentrator.

To the authors’ knowledge, this paper is the first to propose a vision guided assembly or regulation method for PTC frame structures. The research uses online photogrammetry system to provide real-time geometric quality information feedback, elaborates the data analysis algorithm and provides the visualization method for accurate and efficient in site regulation. Furthermore, this paper also provides theories, methods and experiences for other applications that use vision guidance for attitude regulation and digital flexible assembly of large equipment.

The purpose of this paper is to investigate a cylindrical flow insert for a parabolic trough solar collector. Centrally placed and eccentric placed inserts are investigated in a systematic way to determine which configuration leads to the maximum thermal enhancement.

The analysis is performed in SolidWorks Flow Simulation with a validated computational fluid dynamics model. Moreover, the useful heat production and the pumping work demand increase are evaluated using the exergy and the overall efficiency criteria. The different scenarios are compared for inlet temperature of 600 K, flow rate of 100 L/min and Syltherm 800 as the working fluid. Moreover, the inlet temperature is examined from 450 to 650 K, and the diameter of the insert is investigated up to 50 mm.

According to the final results, the use of a cylindrical insert of 30 mm diameter is the most sustainable choice which leads to 0.56 per cent thermal efficiency enhancement. This insert was examined in various eccentric positions, and it is found that the optimum location is 10 mm over the initial position in the vertical direction. The thermal enhancement, in this case, is about 0.69 per cent. The pumping work demand was increased about three times with the insert of 30 mm, but the absolute values of this parameter are too low compared to the useful heat production. So, it is proved that the increase in the pumping work is not able to eliminate the useful heat production increase. Moreover, the thermal enhancement is found to be greater at higher temperature levels and can reach up to 1 per cent for an inlet temperature of r650 K.

The present work is a systematic investigation of the cylindrical flow insert in a parabolic trough collector. Different diameters of this insert, as well as different positions in two dimensions, are examined using a parametrization of angle-radius. To the authors’ knowledge, there is no other study in the literature that investigates the presented many cases systematically with the followed methodology on parabolic trough collectors. Moreover, the results of this work are evaluated with various criteria (thermal, exergy and overall efficiency), something which is not found in the literature.

The purpose of this paper is to describe an experience of R&D in the field of new technologies for solar energy exploitation within the Italian context. Concentrated solar power systems operating in the field of medium temperatures are the main research objectives, directed towards the development of a new and low‐cost technology to concentrate the direct radiation and efficiently convert solar energy into high‐temperature heat.

A multi‐tank sensible‐heat storage system is proposed for storing thermal energy, with a two‐tanks molten salt system. In the present paper, the typology of a below‐grade cone shape storage is taken up, in combination with nitrate molten salts at 565°C maximum temperature, using an innovative high‐performance concrete for structures absolving functions of containment and foundation.

Concrete durability in terms of prolonged thermal loads is assessed. The interaction between the hot tank and the surrounding environment (ground) is considered. The developed FE model simulates the whole domain, and a fixed heat source of 100°C is assigned to the internal concrete surface. The development of the thermal and hygral fronts within the tank thickness are analysed and results discussed for long‐term scenarios.

Within the medium temperature field, an innovative approach is here presented for the conceptual design of liquid salts concrete storage systems. The adopted numerical model accounts for the strong coupling among moisture and heat transfer and the mechanical field. The basic mathematical model is a single fluid phase non‐linear diffusion one based on the theory by Bažant; appropriate thermodynamic and constitutive relationships are supplemented to enhance the approach and catch the effects of different fluid phases (liquid plus gas).

The utilisation of renewable energy sources for generating electricity and potable water is one of the most sustainable approaches in the current scenario. Therefore, the current research aims to design and develop a novel co-generation system to address the electricity and potable water needs of rural areas.

The cogeneration system mainly consists of a solar parabolic dish concentrator (SPDC) system with a concentrated photo-voltaic module at the receiver for electricity generation. It is further integrated with a low-temperature thermal desalination (LTTD) system for generating potable water. Also, a novel corn cob filtration system is introduced for the pre-treatment to reduce the salt content in seawater before circulating it into the receiver of the SPDC system. The designed novel co-generation system has been numerically and experimentally tested to analyse the performance at Karaikal, U.T. of Puducherry, India.

Because of the pre-treatment with a corn cob, the scale formation in the pipes of the SPDC system is significantly reduced, which enhances the efficiency of the system. It is observed that the conductivity, pH and TDS of seawater are reduced significantly after the pre-treatment by the corncob filtration system. Also, the integrated system is capable of generating 6–8 litres of potable water per day.

The integration of the corncob filtration system reduced the scaling formation compared to the general circulation of water in the hoses. Also, the integrated SPDC and LTTD systems are comparatively economical to generate higher yields of clean water than solar stills.

This paper scrutinizes exergy loss and hydrothermal analysis of Linear Fresnel Reflector (LFR) unit by means of FLUENT. Several mirrors were used to guide the solar radiation inside the receiver, which has parabolic shape. Radiation model was used to simulate radiation mode.

Heat losses from receiver should be minimized to reach the optimized design. Outputs were summarized as contours of incident radiation, isotherm and streamline. Outputs were classified in terms of contours and plots to depict the influence of temperature of hot wall, wind velocity and configurations on performance of Linear Fresnel Reflector (LFR) based on thermal and exergy treatment. Four arrangements for LFR units are considered and all of them have same height.

Greatest Nu and E_x can be obtained for case D due to the highest heat loss from hot wall. Share of radiative heat flux relative to total heat flux is about 94% for case D. In case D when T_r = 0.388, As h_ext rises from 5 to 20, Nu_total enhances about 11.42% when T_r = 0.388. By selecting case D instead of case A, E_x rises about 16.14% for lowest T_r. Nu_total and E_x of case D augment by 3.65 and 6.23 times with rise of T_r when h_ext = 5. To evaluate the thermal performance (η_th) of system, absorber pipe was inserted below the parabolic reflector and 12 mirrors were used above the ground. The outputs revealed that η_th decreases about 14.31% and 2.54% with augment of T_in and Q if other factors are minimum.

This paper scrutinizes exergy loss and hydrothermal analysis of LFR unit by means of finite volume method. Several mirror used to guide the solar radiation inside the receiver, which has parabolic shape. DO model was used to simulate radiation mode. Heat losses from receiver should be minimized to reach the optimized design. Outputs were summarized as contours of incident radiation, isotherm and streamline.

Present investigation conducts a study on the hydrothermal features of a double flow Parabolic Trough Solar Collector (PTSC) equipped with sinusoidal-wavy grooved absorber tube and twisted tape insert filled with nanofluid. This paper aims to present an effectual PTSC which is comprised by nanofluid numerically by means of finite volume method.

The beneficial results such as pressure drop inside the absorber tube, mean predicted friction factor, predicted average Nusselt number and hydrothermal Performance Evaluation Criteria (PEC) are evaluated and reported to present the influences of numerous factors on studied interest outcomes. Effects of different Reynolds numbers and environmental conditions are also determined in this investigation.

It is found that using the absorber roof (canopy) can enhance the heat transfer ratio of PTSCs significantly during all studied Reynolds numbers. Also, it is realized that the combination of inner grooved surface, outer corrugated surface and inserting turbulator can improve the thermal-hydraulic characteristics of PTSCs sharply.

Novel PTSC (N.PTSC) filling with two Heat Transfer Fluids (HTFs), inner and outer surface corrugated absorber tube, absorber roof and inserting twisted tape (N.PTSC.f) has the highest PEC values among all novel configurations along all investigated Reynolds numbers which is followed by configurations N.PTSC with two HTFs and inserting twisted tape (N.PTSC.e), N.PTSC with two HTFs and outer surface corrugated absorber tube (N.PTSC.b) and N.PTSC with two HTFs and inner surface corrugated absorber tube (N.PTSC.c), respectively. N.PTSC.f Nusselt number values can overcome the high values of friction factor, and therefore is introduced as the most efficient model in the current study.

Effective cooling is one of the challenges for photovoltaic thermal (PVT) systems to maintain the PV operating temperature. One of the best ways to enhance rate of heat transfer of the PVT system is using advanced working fluids such as nanofluids. The purpose of this research is to develop a numerical model for designing different form of thermal collector systems with different materials. It is concluded that PVT system operated by nanofluid is more effective than water-based PVT system.

In this research, a three-dimensional numerical model of PVT with new baffle-based thermal collector system has been developed and solved using finite element method-based COMSOL Multyphysics software. Water-based different nanofluids (Ag, Cu, Al, etc.), various solid volume fractions up to 3 per cent and variation of inlet temperature (20-40°C) have been applied to obtain high thermal efficiency of this system.

The numerical results show that increasing solid volume fraction increases the thermal performance of PVT system operated by nanofluids, and optimum solid concentration is 2 per cent. The thermal efficiency is enhanced approximately by 7.49, 7.08 and 4.97 per cent for PVT system operated by water/Ag, water/Cu and water/Al nanofluids, respectively, compared to water. The extracted thermal energy from the PVT system decreases by 53.13, 52.69, 42.37 and 38.99 W for water, water/Al, water/Cu and water/Ag nanofluids, respectively, due to each 1°C increase in inlet temperature. The heat transfer rate from heat exchanger to cooling fluid enhances by about 18.43, 27.45 and 31.37 per cent for the PVT system operated by water/Al, water/Cu, water/Ag, respectively, compared to water.

This study is original and is not being considered for publication elsewhere. This is also not currently under review with any other journal.

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Top of the list of the 14 “Grand challenges for engineering in the 21st century” that have been identified and published by the US National Academy of Engineering (NAE) is the need to harness the power of the sun by commercializing affordable solar energy. As the NAE observes, “we only need to capture one part in 10,000 of the sunlight that falls on the Earth to meet 100 percent of our energy needs.” At present solar's share of the total energy market remains rather small, well below 1 percent of total energy consumption. However, the committee has chosen challenges that they feel can, through creativity and commitment, be realistically met, and a range technologies that start go some of the way to meeting the solar energy generation problems – from PV cells to utility scale thermal power plants – are now not only well in hand, but are seeing major growth in terms of adoption.

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