Dish Systems Research Articles

Experimental comparative analysis of solar system productivity and performance in water distillation: Solar stills vs. parabolic dish systems

This study aims to evaluate the practical suitability of two solar technologies, Solar Stills and Solar Parabolic Dishes, in meeting energy demands for various applications, including preparing distilled water and other applications. Through the analysis, solar still systems were found to be the preferred choice for distilled water production due to their ability to yield significant amounts of pure water through simple or advanced designs. Conversely, the results showed that solar parabolic dishes are more suitable for applications requiring higher temperatures, such as cooking, as they concentrate solar radiation into smaller focal points. This study presents essential information for efficient energy management in specific water treatment applications, assisting in the selection of appropriate solar technologies. The results showed that the Parabolic Dish Concentrator (PDC) achieved an impressive temperature of 96.5 °C. Nonetheless, even though these high temperatures were attained, the experiments did not lead to the production of distilled water. Based on the results, the thermal efficiency of the solar still was calculated at 5.6 % without modification and 9.4 % with the implemented modification. Conversely, the solar still's productivity witnessed a notable increase of around 66.6 % with a straightforward modification involving the incorporation of operational fans. Additionally, there was a substantial enhancement in efficiency, registering a remarkable rise of 67.8 %.

Hybridization solutions for solar dish systems installed in the Mediterranean region

One of the main challenges facing the commercialization of parabolic solar systems is their high initial cost, which is not competitive with the low cost, ease of operation, and reliability of photovoltaic technology. However, one potential solution to maximize their energy producibility and improve their economic profitability is to hybridize the power conversion unit. By enabling reliable power generation and reducing reliance on the availability of solar thermal energy, hybridization can be a valid solution to improve the efficiency and practicality of parabolic dish solar systems. This study aims to assess the energy performance of two hybrid parabolic dish systems: the dish-Stirling system located at the University of Palermo, and the dish-Micro Gas Turbine system located at ENEA Casaccia. Different scenarios were examined by varying the installation site and operational strategy, as well as exploring hybridization solutions of the solar source with conventional fossil fuel or renewable ones. The findings suggest that hybridizing parabolic dish systems with conventional fuels or renewable energies greatly enhances their performance, increasing operational hours and maximizing energy producibility.

Prediction of focal image for solar parabolic dish concentrator with square facets-an analytical model.

Solar parabolic dish concentrator is one of the high-temperature applications of more than 400°C for thermal and electrical power generation. In the solar parabolic dish concentrator, the arrangement of reflectors over the surface area is the significant factor for effective concentration of solar radiation. Also, focal image is one of the most influencing parameters in the design of receiver. Among the various reflectors, the square-shaped reflectors (facets) are comparatively effective in converging the incoming radiations to attain better focal image. In this regard, an attempt has been made to predict the focal image diameter of a solar parabolic dish concentrator with a square facet of different influencing parameters using a novel mathematical model. The influencing parameters considered for the study are aperture diameter, rim angle, and facet length of the dish concentrator. Using the model, the focal image dimension and aperture area of a solar parabolic dish concentrator with square facets can be predicted accurately for efficient design of a solar parabolic dish collector system. Finally, the model is validated with the experimentally obtained focal image diameter. The current model is in good agreement with the experimental value, with a deviation of 8.84%. Hence, the proposed model can be used for the design of parabolic dish systems.

Innovative Solar Concentration Systems and Its Potential Application in Angola

Energy demands have been increasing worldwide, endangering the future supply–demand energy balance. To provide a sustainable solution for future generations and to comply with the international goal to achieve Carbon Neutrality by 2050, renewable energies have been at the top of the international discussions, actively contributing to the energy transition and climatic policies. To achieve the international goal, Angola proposed a long-term strategy that promotes a fair and sustainable development of the national territory by means of improving the electric sector. Among all the renewable resources, solar energy is found to be the most promising solution since it has the second major renewable energy potential in Angola. However, the main problem related to solar energy is the efficiency of the solar systems and the electrical and thermal energy storage. As part of the solution, Concentration Solar Power (CSP) can make a sounder contribution to the transformation of the Angolan energy sector since it enables a significant increase in energy intensity through the concentration of solar energy. Moreover, the large applicability of this technology can contribute to the development of the rural regions which still struggle for energy equity. By considering the potential of CSP, this work presents the status of the Angolan energy sector, and focus is provided on the solar potential of the country. The advantages of the CSP technologies with emphasis on the parabolic dish systems are presented, and the contribution and innovative solutions for the enhancement of thermal efficiency are presented.

Experimental and techno-economic analysis of two innovative solar thermal receiver designs for a point focus solar Fresnel collector

In this paper, techno-economic analysis and the experimental campaign for a new solar concentrating system are presented. Two novel receivers (Jet impingement receiver with mesh structure & helical channel receiver) are tested on a novel collector technology. The collector technology integrates the two established models of solar concentrating technologies, which are linear Fresnel reflector technology and central receiver technology, into the new concept called the Point Focus Fresnel Collector (PFFC). It is found that the PFFC system with jet impingement receiver and mesh structure provides higher thermal efficiency and manufacturing ease compared to parabolic dish systems. Maximum thermal efficiency of jet impingement receiver is highest at 87% whereas that for helical channel receiver is 83%. Average thermal efficiency of jet impingement receiver is 61% whereas that for helical channel receiver is 58%. Economic analysis of the system reveals that the discounted payback time for the PFFC system is only 5.5 years and less than one year compared to diesel and electricity powered steam generators respectively at an inflation rate of 2.5%. Substantial saving is predicted with PFFC system compared to diesel and electricity powered steam generator. For all discount rates in the range of 2.5–25%, the levelized cost of energy (LCOE) for PFFC system is much lower than that of LCOE in Saudi Arabia for conventional system. Since the LCOE in most of the Middle East and North Africa (MENA) countries is higher than the LCOE in Saudi Arabia, therefore, the PFFC system is also suitable for other MENA countries where average direct normal irradiation values are comparable to Saudi Arabia.

Theoretical and experimental investigation of a novel point‐focus Fresnel collector system with a novel receiver

Here, experimental results for testing a novel solar concentrating system are presented. The novel receiver is tested on a technology that combines the two proven concepts of solar concentrating technologies (linear Fresnel reflector (LFR) and central receiver technologies) into a new concept called focal point Fresnel collector (PFFC) with a polar sun-tracking system. The PFFC system works by concentrating direct solar irradiation using several flat mirrors positioned over a square-rotating surface that follows the sun. Considering the solar elevation, the reflection is achieved using the Fresnel reflection concept. Rectangular mirrors of LFR technology are discretised into small square mirrors to achieve point focusing. A concentration ratio of 600 has been achieved, which is like that of parabolic dish (PD) systems. Mathematical modelling of the system is presented along with the experimental results. Furthermore, the PFFC system with the novel receiver provides similar thermal efficiency with comparatively higher manufacturing ease than the PD system. Besides, a maximum thermal efficiency of 87% has been achieved.

Toxic effects of norfloxacin in soil on fed and unfed Folsomia candida (Isotomidae: Collembola) and on gut and soil microbiota

Soils contaminated with antibiotics may exert effects on soil-dwelling animals. A systematic ecological toxicity assessment of norfloxacin on the soil collembolan Folsomia candida (F. candida) was therefore conducted in soil and Petri dish systems with and without feeding at the population, individual and cellular levels. The indicators survival, reproduction, antioxidant enzyme activities peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD), malondialdehyde (MDA) contents and gut microbiota were studied. The surrounding soil microbiota were also investigated because F. candida can ingest soil microbiota that may have effects on the gut microbiota. In general, the toxicity of norfloxacin to F. candida in contaminated soil without food addition was higher than in contaminated soil with food addition. Norfloxacin had little effect at population and individual levels but antioxidant enzyme activities changed significantly in treatments with longer exposure times or higher norfloxacin concentrations. CAT was more sensitive than SOD or POD. The diversity indices and composition at phylum level of the gut microbiota showed little change. However, the operational taxonomic units in the gut decreased in the presence of norfloxacin. The relative abundance of Wolbachia, the predominant bacterial genus in the gut, decreased significantly with increasing soil norfloxacin concentration. Wolbachia may therefore be a promising bioindicator in the assessment of norfloxacin pollution of soils at environmental concentrations.

Performance enhancement of cavity receivers with spillage skirts and secondary reflectors in concentrated solar dish and tower systems

A cavity receiver geometry may represent a better option than an external receiver geometry for high temperature solar power systems because of reduced thermal losses. However, a limitation is that the small aperture necessary for an efficient (and affordable, practical) cavity receiver may lead to high spillage losses, negating the thermal efficiency gains. In this study, Monte Carlo ray tracing is coupled with heat transfer models to assess the benefit of secondary reflectors and spillage skirts on the performance of cavity receivers in the context of both dish and tower CSP systems. The heat transfer fluid is chosen as liquid sodium with inlet and outlet temperatures of 520 °C and 740 °C respectively. A spillage skirt and three different types of secondary reflectors, including conical, trumpet and compound parabolic concentrator (CPC) reflectors are investigated to decrease the energy loss. The results show that the spillage skirt helps in greatly decreasing the aperture size, while simultaneously reducing the spillage loss. The conical and trumpet reflectors increase the efficiency by reflecting rays outside the cavity inlet into the receiver, but the CPC does not achieve efficiency gains comparable to the other designs in both the dish and tower systems. For dish systems, highest efficiency is obtained with a combination of a spillage skirt and conical or trumpet reflectors, with a 1.0% increment in receiver efficiency compared to the best cylindrical receiver. For the tower system the efficiency gain is approximately 1.3% relative to the optimised cavity receiver alone.

Reduced effect of mineral oil toxicity using four-well culture dish in sheep embryo production

Abstract Mineral oil (MO) as a barrier can minimize temperature, osmolality and pH fluctuation in the oocyte/embryo culture medium. Regardless of these advantages, MO acts as a potential source of embryo-toxic compounds which can affect embryo viability. This study was conducted to assess the signs and effects of the four-well culture dish (FW) and microdrop culture systems (MD) on reducing the harmful effects of mineral oil during the in-vitro production of sheep embryos. Oocytes retrieved from abattoir-derived ovary were in-vitro matured, fertilized and cultured in MD and FW, overlaid with two different lots of mouse embryo tested mineral oils (SMO1; nMD = 133, nFW = 103, and SMO2; nMD = 137, nFW = 144) and a clinically tested mineral oil (OMO; n = 107) as a control group. The results showed that using SMO1 and SMO2 in the MD can dramatically decrease cleavage and blastocyst rates. Although they did not show any membrane damage after IVM and 24 h after IVF, the sign of damage was appeared at 48 h after fertilization and completely destroyed the blastomere membrane at 72 h after fertilization, while the FW did not affect membrane integrity. In conclusion, FW compares to the MD, can reduce the deleterious effects of mineral oil on sheep embryos.

Suppression Of Natural Convection And Radiation Heat Losses In Solar Cavity Receivers: A Novel Approach

The concentrating solar power technology has great potential to be used for energy production and it is a promising alternative to conventional fossil fuel-based energy technologies, such as coal power plants, due to the abundance of solar energy as an energy resource, as well as its minimal impact on the environment. The parabolic dish receiver assembly is one such promising concentrating solar power technology. It usually consists of a reflector in the form of a dish with a downward-facing receiver at the focus of the dish. A cavity receiver is used to maximise the absorption of the concentrated flux. However, the receiver is subjected to environmental variations, as well as changes in receiver inclination angle, which lead to heat losses that affect the overall receiver’s performance. The need for the commercialisation of economically viable parabolic dish systems necessitates further in-depth investigation into cavity receiver designs. As the cavity receiver plays a critical role in transferring solar heat to the engine, any heat loss from the cavity receiver can significantly reduce the efficiency and, consequently, the system’s cost effectiveness. It is therefore essential to assess and effectively minimise heat loss in the cavity receiver to improve the thermal performance of the system, which can contribute to the commercialisation of this type of technology. This novel approach of suppressing natural convection heat loss in a cavity receiver was investigated. The proposed model has not been observed in literature. A cavity receiver with plate fins attached to the inner aperture surface was investigated as a possible low-cost means of suppressing natural convection heat loss in a cavity receiver. Employing air as the working fluid, laminar natural convection heat transfer from the cavity receiver with plate fins attached to the inner aperture surface was investigated for a range of Rayleigh numbers, inclination angles, and fin heights and thicknesses

A novel ultralight dish system based on a three-extensible-rod solar tracker

The use of dish systems is among the most potential methods for solar power collection. However, the popularization of the application of traditional dish systems has been impeded because they are heavy, structurally complex, and costly. Accordingly, a novel ultralight dish system is proposed; it consists of a cable mesh reflector, an ultralight thermoelectric conversion device, and a three-extensible-rod (TER) solar tracker. Compared with previous reflectors consisting of rigid solid panels, the reflector of the proposed dish system (PDS) adopts an ultralight rigid–flexible combined structure based on a space cable mesh reflector antenna. The lightweight thermoelectric conversion device of the PDS is reasonably considered. Thereafter, a TER solar tracker (specifically, 3-RPS) is mainly selected and designed for the PDS. Through an inverse kinematic analysis of the tracker, a sun-tracking control strategy of height variation is employed to reduce the number of sections in each extensible rod from three to two and to decrease total energy consumption. Meanwhile, a compound joint consisting of hook and rotary joints is substituted for the spherical joint of the solar tracker to overcome its inadequate rotational range and facilitate fabrication. By setting the PDS to an extreme orientation and subjecting it to wind and gravitational loads, its structural parameters are further determined through analysis and optimization. Although the surface density of the PDS is only approximately 1 kg/m2, the system performs satisfactorily even when subjected to loads. The dynamic model of the PDS is established by the Newton–Euler formulation. The power requirement of the PDS is determined through the dynamic analysis; it is found that during winter solstice, its maximum power is only 0.024 W, and the daily energy consumption is only 210.05 J. Finally, sun-tracking experiments on the TER solar tracker are performed to verify the theoretical and simulation analysis results; the sun-tracking accuracy is estimated to be within ±0.7°, which satisfies the PDS requirement although the machining precision of its components is not high.

Experimental and Comparison Study on Two Solar Dish Systems with a High Concentration Ratio

Two high concentrating solar systems have been established with dish concentrator and plane-mirrors array concentrator. In the paper, the thermal performance has been experimentally studied with jet water cooling device and flat microchannel water-cooled device. The experimental results show that the maximum surface temperature difference of the dish concentrating system is greater than 20°C, while the plane-mirrors array system is lower than 4°C. It indicates that the plane-mirrors array concentrator has better uniformity. As the concentration ratio increases, the electrical efficiency of the concentrating photovoltaic system gradually decreases. When the concentration ratio is 200, the electrical efficiency of the photovoltaic system is 25%. The concentration ratio of 500 times or less is considered to be a suitable value, and then the electrical efficiency can still exceed 20%. It is found that the plane-mirrors array solar system is more suitable for the photovoltaic system than dish type system, which is only suitable for thermal power generation system.

Modeling of convective heat loss from a cavity receiver coupled to a dish concentrator

The more heat losses from the cavity are associated with the higher temperature achieved inside the cavity receiver of a parabolic dish system. The heat loss from the cavity receiver takes place by all three modes, but the determination of convection heat losses are the difficult task due to complexity of flow and temperature profile near the cavity. Due to diverse wind effects in real scenario, the increase in the convective losses significantly impact the overall performance of the parabolic dish systems. Numerous studies have investigated the heat loss from various receiver geometries under natural and forced convection conditions. However there is a marked absence of studies that take into account the effect that the dish may have on the heat loss; the interaction between wind and the dish structure can affect the local air speed at the cavity inlet and thus the heat loss as well. This work aimed to investigate the heat losses from the coupled dish-cavity receiver system particularly for forced convection conditions. Numerical simulation were performed using the ANSYS CFX package to estimate the convective heat losses from the cavity receiver at various wind directions and dish-cavity orientation. The heat losses were assessed considering wind velocities from 0 to 20 m/s, together with a range of wind incidence angles and dish tilt angles. The results showed that the orientation and position of the parabolic dish has a significant effect on the heat loss from the cavity receiver. The dish structure reduced the heat loss from the cavity at most of the working orientations except in the case of flow parallel to the aperture of the dish. A critical velocity was perceived to separate the dominance of mixed/forced convection over natural convection. At lower velocities than the critical velocity, natural convection was found to be dominant. But due to orientation and tilt angle, the dish structure provided a significant impact on the forced convection. Nusselt number correlations is proposed to calculate the natural convection and combined convection from the coupled dish-cavity system. A relatively less strength of wind incidence angle to the tilt angle was observed in the presence of the dish structure in the flow field.

A Review on Solar Secondary Concentrator

Concentrating solar power (CSP) is a solar thermal technology that generates electricity from thermal energy through the sun.The electricitycan be generated with four different types of CSP technologies that include Parabolic Dish (PD) systems. In order to make this technology more practical, the efficiency of the solar technology should be improved.Solar concentration is one of the main aspects that can affect the system’sefficiency. This paper reviewed solar secondary concentrators and discussed their designs and performance. Besides, their strengths and weaknesses were compared. Generally, thesecondary concentrators couldincrease the solar concentration of the solar technologyup to 93 percent.

Thermal analysis of porous volumetric receivers of concentrated solar dish and tower systems

Abstract In this article, thermal analysis of Solar volumetric receiver used in concentrated solar thermal power systems is studied. A cylindrical volumetric receiver used in the parabolic dish collector and solar power tower is analyzed using a finite element method based tool COMSOL multiphysics software. A non uniform Gaussian distribution based heat influx is applied at the receiver to mimic the actual conditions. The steady state operation of the receiver is studied for various porosity and thermal conductivity of the solid phase. Different parameters of Gaussian distributions corresponding to different flux profile conditions are studied. The Gaussian profile heat flux amounting to 1 MW/m2 results in the Gaussian like temperature distribution of the fluid phase near the receiver exit region. Higher thermal conductivity of 200 W/(m K) coupled with the high porosity of 0.7 leads to the better operational efficiency of the receiver. Lower porosity results in higher peak temperature in the fluid phase and higher thermal conductivity laterally spreads the temperature across the receiver. The intermittent solar flux condition is realized through transient response study of flux conditions. The temperature gain rate in transient case is found to be approximately 24 K/s while the temperature drop is around 29 K/s.

Experimental study on heat losses from external type receiver of a solar parabolic dish collector

Solar parabolic dish systems find applications in steam generation for cooking, laundry process industries etc. Receiver is an important component of a solar parabolic dish collector system. Since the concentration ratios are very high for these kind of systems, high temperatures are present in the receiver, which increases the possibility of large amount of thermal losses. Heat losses from receiver can greatly reduce the efficiency of the collector system. Efficient design is required to minimise losses and improve conversion efficiency. This paper aims to present an experimental investigation of heat losses from circular receiver, external type of a 16m2 solar parabolic dish concentrator system. Receiver geometry is of a short cylinder type. Convection and radiation losses from the receiver are studied experimentally. Results show that the receiver surface with high temperature of 150 °C is exposed to ambient leading to average thermal loss of 260 Watts. Results of this experimental investigation emphasize the need for efficient receiver design to reduce heat losses.

Experimental evaluation of a novel solar receiver for a micro gas-turbine based solar dish system in the KTH high-flux solar simulator

This work presents the experimental evaluation of a novel pressurized high-temperature solar air receiver for the integration into a micro gas-turbine solar dish system reaching an air outlet temperature of 800 °C. The experiments are conducted in the controlled environment of the KTH high-flux solar simulator with well-defined radiative boundary conditions. Special focus is placed on providing detailed information to enable the validation of numerical models. The solar receiver performance is evaluated for a range of operating points and monitored using multiple point measurements. The porous absorber front surface temperature is measured continuously as it is one of the most critical components for the receiver performance and model validation. Additionally, pyrometer line measurements of the absorber and glass window are taken for each operating point. The experiments highlight the feasibility of volumetric solar receivers for micro gas-turbine based solar dish systems and no major hurdles were found. A receiver efficiency of 84.8% was reached for an air outlet temperature of 749 °C. When using a lower mass flow, an air outlet temperature of 800 °C is achieved with a receiver efficiency of 69.3%. At the same time, all material temperatures remain below permissible limits and no deterioration of the porous absorber is found.

“One-Pot” Solar Fuels

Chemists have always taken great pride in simplifying a complex multistep chemical synthesis into a single step process, in just one reactor. The motivation for doing so, apart from demonstrating synthetic competency and elegance, is the pursuit of green and sustainable solutions to chemical problems, as single step strategies have the inherent advantage of being atomically, energetically and economically efficient, as well as environmentally friendly and responsible.

High temperature solar receiver and thermal storage systems

For concentrating solar power (CSP) plants to become cost competitive, it is necessary to design systems with significantly higher cycle efficiencies and to innovate cost-effective storage systems and materials. Higher cycle efficiency demands higher operating temperature, which implies that the optical system for the solar receiver needs to be designed for higher concentration ratio. This paper reviews the present technologies for high temperature solar receivers associated with power dish and power tower systems. Significant research and development work required for high temperature storage systems and materials is also discussed. Recently, the supercritical carbon dioxide (s-CO2) Brayton cycle is identified as a potential candidate to realize significantly higher thermal efficiency at high operating temperature and pressure. Recent developments and challenges involved in development of solar receivers and thermal storage systems for such applications are also presented.

The impact of the parabolic dish concentrator on the wind induced heat loss from its receiver

To achieve higher operating temperatures, power output and system efficiencies in parabolic dish cavity receivers, larger dish sizes and structures are used to increase the concentration ratio. This increases capital investment and installation costs, which in turn places a much stronger emphasis on accurately predicting the performance of the system and the heat loss from it. Numerous studies have investigated the natural convection heat losses from cavity receivers, and some have examined a cavity exposed to wind. However, the effect of the dish on the wind flow and subsequently the heat loss from the receiver has not been widely considered.In this work, computational fluid dynamics was used to model the flow of air around a parabolic dish concentrator operating at varying angles of operation. The flow fields were validated using wind tunnel testing and published data regarding the aerodynamic characteristics of parabolic dishes. The results showed that the orientation of the dish has a significant effect on the flow structure near the receiver. Subsequently, using the validated method, the convective heat loss from the receiver of a large parabolic dish system was determined for a range of operating conditions.The results support the assertion that the flow characteristics near the cavity receiver aperture depend strongly on the orientation of the dish structure. This resulted in the calculated heat loss being up to 40% lower than previous studies where the presence of the dish was included. As such, the wind flow around the dish needs to be accounted for when analyzing the performance of parabolic dish systems to avoid an overly conservative and hence more expensive design.