Solar Collector Research Articles

Optimization of a hybrid renewable energy system for off-grid residential communities using numerical simulation, response surface methodology, and life cycle assessment

This paper presents an optimized hybrid renewable energy system tailored for off-grid residential communities, integrating wind, solar, and hydrogen technologies to meet electricity, cooling, heating, and water needs. The proposed optimization methodology combines numerical simulation, response surface methodology (RSM), and life cycle assessment (LCA), ensuring robust performance across diverse conditions. Key components include fuel cells, reverse osmosis systems, heat pumps, photovoltaic/thermal solar collectors, wind turbines, and hydrogen generation systems. The optimization process targets critical variables such as PVT panel area, the number of wind turbines, and fuel cell power. The optimal configuration was found to include 24 small-scale wind turbines, 159.46 m2 of PVT collectors, and 79.73 kW of fuel cell power. This configuration generated surplus electricity with net electricity usage (NEU) values of −123084.27 kWh/year in New York, −224245.29 kWh/year in Forks, and −215949.30 kWh/year in Santa Barbara. Additionally, the optimized systems achieved a significant reduction in life cycle cost (LCC), with Forks showing the lowest LCC at 304428.97 USD. The environmental impact was also minimized using the novel optimization approach, with the optimized systems achieving negative 100-year global warming potential (GWP100) values, indicating a net reduction in greenhouse gas emissions.

Enhancement and characteristics study of parabolic trough solar collector by using magnesium oxide coating on solar tubes

Enhancement and characteristics study of parabolic trough solar collector by using magnesium oxide coating on solar tubes

A facile route derived solar selective nickel-cobalt oxide thin films via spraying process

Abstract This work focuses on understanding the role of annealing temperature on the solar selective performance of nickel-cobalt oxide thin films successfully sprayed onto Al substrates using the spray pyrolysis technique. The synthesized nickel-cobalt oxide thin films (~ 725± 20 nm thick) were post annealed at (400, 500 and 600) °C. The XRD and FESEM outcomes appeared high crystalline quality with crystal grains in the range of (27 – 52) nm and improved surface morphology for the sprayed thin films. The optical properties reflect solar absorptance ~ (85.2 %) and the thermal emittance ~ (4.45 %). The hardness and the Young’s modulus were (19.1 GPa) and (104 GPa) respectively. The aforementioned results are for the film annealed at 600 °C. The prepared and post annealed nickel-cobalt oxide thin films show band gap energies in the range of (1.15 – 1.38) eV. The nickel-cobalt oxide thin films also possess excellent thermal stability at higher temperature which makes them interesting candidate for solar absorbing and thermal collector applications.

Parameter identification and uncertainty evaluation in quasi-dynamic test of solar thermal collectors with Monte Carlo method

This work presents a comparison between two methods used for parameter identification and calculation of parameter uncertainty applied to the measured data of solar thermal collectors when tested according to ISO 9806:2017. One method is using a weighted least square (WLS) fit and the partial derivative approach described in the GUM (the Guide to the Expression of Uncertainty in Measurement). The second is using the Monte Carlo (MC) method, also described in GUM. Uncertainty evaluation by Monte Carlo method is based on a probabilistic approach and is an alternative way for identification of parameters and determination of the uncertainties. In this work the results were obtained according to Quasi-Dynamic Test (QDT) method for a flat plate collector and an evacuated tubular collector. The least squares (LS) method and a nonlinear regression method (MPFit) are used in the identification of parameters for each iteration of the MC method. For the implemented MC method computation times are also discussed. One disadvantage of the MC method is the computation time which depends on the number of samples in the experimental test quantity files, however with this study we think that the advantages of the MC method outweigh the disadvantages, and it is useful even as a complementary tool in QDT testing of collectors.

Improvement of heat transfer within solar water heater’s tubes (SWH) using nanofluids

This research offers a numerical study of steady and laminar mixed convection flow in a circular pipe as part of a flat plate solar collector, which is crossed by nanofluids. The pipe is kept at a constant wall temperature and then at a constant heat flux, which represents the solar radiation received by the pipe. The governing coupled equations are solved with the finite volume approach. Computations are carried out using an in-house computer code, which has been satisfactorily validated by comparison to previous investigations. Empirical relations are used to predict the effective thermal conductivity and viscosity of nanofluids. The results are investigated using dynamic and thermal fields, with a special emphasis on the Nusselt number calculated along the active wall. They demonstrate that increasing the volume fraction of nanoparticles and Reynolds number improves heat transfer.

On the industrial solar drying of tomatoes in Biskra : A preliminary study

The objective of this study is to carry out a pre-feasibility study of solar industrial drying as a preliminary step before investing in large-scale solar drying projects in Algeria. Our primary goal is to promote the use of industrial solar dryers and to incite public authorities and industrials to invest in this promising niche. This work aims to strengthen the contribution of renewable energies and particularly solar energy in the sustainable development of the agri-food sector. Indeed, using solar energy will reduce the energy consumption and decrease greenhouse gas emissions of drying process. The prefeasibility analysis is achieved using the RETScreen Suite. Our study aims to investigate energy consumption of an industrial solar dryer of tomatoes, located in the city of Biskra. Various parameters as solar collector type and drying air temperature were tested and discussed. The obtained results showed a reduction in energy consumption up to 35%. Likewise, the reduction of GHG emissions recorded very favorable rates. This study's findings provide a preliminary vision for investors in the agri-food sector to build their project so they may maximize their profit while supporting the environment by lowering carbon emissions.

Experimental investigation of non-uniform heating effect on flow and heat transfer of supercritical carbon dioxide:An application to solar parabolic trough collector

In order to reduce the carbon dioxide emission, the supercritical carbon dioxide (sCO2) Brayton cycle is a good choice to convert solar energy into power using solar parabolic trough collectors (PTCs). Because the earth rotation induced non-uniform flux distribution threatens the safe operation of absorber tubes, we investigate the flow and heat transfer of sCO2 in a horizontal tube under non-uniform heating, with the mass fluxes, average heat fluxes and pressures in the ranges of (397–1244) kg/m2s, (99–413) kW/m2, and (7.5–15.7) MPa, respectively. On the contrary to the classical treatment of supercritical fluid (SCF), SCF is treated in a multiphase framework. It is found that, compared with the sCO2 heat transfer in horizontal tubes under uniform heating, the non-uniform heating not only enhances heat transfer, but also increases friction factors. Besides, the non-uniform heating weakens the stratification effect, but the difference of heat transfer between the top and bottom generatrixes cannot be completed eliminated. It is observed that the larger vapor-like-layer thicknesses on tube walls may switch the sCO2 heat transfer from normal heat transfer (NHT) to heat transfer deterioration (HTD). Three heat transfer mechanisms are commented by using the dimensionless numbers regarding the pseudo-boiling in supercritical pressures.

Numerical investigation of a heat pipe receiver for the solar dish collector humidification–dehumidification desalination system

Numerical investigation of a heat pipe receiver for the solar dish collector humidification–dehumidification desalination system

Energetic and economic analysis of a novel concentrating solar air heater using linear Fresnel collector for industrial process heat

Industrial processes share a relevant portion of global energy consumption. A large variety of high energy-demanding industrial processes need hot air in the medium temperature range, provided by natural gas combustion or by electricity. Hot air is used as a medium in a large variety of processes such as drying, curing, and thermal treatments of several products and materials. Heat can be provided by solar thermal technologies aimed at the sustainable industry. Non-concentrating flat plate type solar collectors can directly heat air up to 100 °C while higher temperatures can be achieved using linear concentrating technology. In this study an innovative system using linear Fresnel collectors directly provides hot air for the industry up to 350 °C, avoiding the need for liquid heat transfer fluids. Accordingly, the installation is simplified, and lower installation and maintenance requirements are expected compared to other solar technologies. The present studies provide an energetic and economic analysis of the concentrating solar air heater, considering a medium-scale benchmark as a reference case in representative European locations. The results indicate that the solar technology here presented can be economically competitive with conventional natural gas heating, having a huge potential for fossil fuel source replacement in hot air based industrial processes.

Weaknesses of steady state analysis when used for selecting solar air heaters

The paper highlights the constrains faced by the user when choosing the most appropriate solar collector from a set of collectors belonging to the same category. Two basic kinds of one porous and one non-porous with single flow/pass flat solar air heaters were tested. The collectors have the same size but different internal shapes and absorber materials. The two collectors were tested and a shading procedure was implemented in order to emphasize several aspects related to the thermal inertia of the collectors. Comparison has been made between the efficiency values obtained experimentally. The shade test shows a faster decrease of the outlet air temperature for V-porous absorber collector in comparison with the U-corrugated absorber collector i.e. 6 °C and –3.5 °C respectively in a time interval of 74 s. Exposing the collectors on a fresh heating cycle under a low stability radiative regime (450–750 W/m2) one observe that 60% of the first 180 s the corrugated collector outperforms the porous collector; after that interval of time the porous collector becomes more effective. The low thermal inertia of the solar air collectors yields high variation of the thermal efficiency in days with low stability of the radiative regime. In such days, using measured series of solar irradiance data with long sampling period between two successive measurements does not allow a proper choice of the most appropriate solar collector type.

Influence of Nanofluid Types on the Enhancements of Solar Collector Performance

Nowadays, solar energy is attracting a great deal of research interest. Optimizing solar collectors by incorporating nanoparticles into the base fluid is one area of current research focus. This study investigates how the types of nanoparticles affect the performance of solar collector. We investigated the effects of various nanoparticles types on performance of solar collector. Nanofluid 1 (alumina nanoparticles; Al2O3) and nanofluid 2 (silicon dioxide nanoparticles; SiO2) were combined with water. Nanofluids are made with a constant nanoparticle concentration of 0.5 vol. %. Data collection was conducted under Iraqi environments during the three-month study period (January, February, and March) from 9 a.m. to 3 p.m. In particular, the data for every two-hour period is displayed. The results demonstrated the collector’s efficiency significantly influenced by nanoparticles’ type. At 1 p.m. in February, nanofluid 1 was 4.8% in front of nanofluid 2. The significance of nanoparticle materials in enhancing solar collector efficiency is highlighted by this outcome. When water-based fluid in the solar collector was compared to nanofluids 2 and 1, the latter demonstrated a typically better efficiency. Nanoparticle owns higher thermal conductivity which is one of the reasons behind the increments of the nanofluid's overall conductivity.

Thermal Efficiency Analysis of a 1 kW ORC System with a Solar Collection Stage and R-245fa Working Fluid: A Case Study

A thermal efficiency analysis of an organic Rankine cycle (ORC) system enables its performance to be evaluated; for this purpose, critical system components, including the turbine and the boiler, must be scrutinized. ORC plants can operate under various regimes, such as simple, regeneration, and reheat work modes. Organic fluids such as R-245fa integrate low-temperature sources such as solar radiation. However, a literature review revealed limited research on the impact of a solar collection system on the overall thermal efficiency of an ORC system during the regeneration stage. In this study, we examined the thermal efficiency behavior of an ORC plant with a 1 kW generator operating in simple and regeneration modes with a solar collection stage. The results show that the thermal efficiency in simple mode was 35.27%, while in regeneration mode with solar collection it reached 51.30%. Improving the thermal efficiency of a thermodynamic cycle system can reduce CO2 emissions. The operating temperature ranges facilitate the development of a methodology for industries to implement ORC systems in their manufacturing processes, thereby utilizing waste heat from industrial operations.

Modeling the Optimal Distance Between Pipes in a Solar Water Heating Collector

This study proposes a mathematical model based on normal distribution to determine the optimal distance between pipes in a solar water heating collector. The model takes into account key system parameters such as material thermal conductivity, heat losses, and solar radiation intensity. Experimental data collected for model validation confirm its accuracy and adequacy. The main results show that the maximum efficiency (η) of the solar water heating collector is achieved at a pipe spacing of approximately 0.0469 m. The analytical method demonstrates a smooth decrease in efficiency when deviating from the optimal distance, whereas the experimental data indicate a high sensitivity of the system to changes in this parameter. Thus, the proposed model is a useful tool for designers, allowing for precise prediction of optimal system parameters and increased efficiency. Further research and experiments are planned to improve model accuracy and expand its applicability.

Potential of solar thermal collector combined with dual phase change materials for different energy demands: An energy, economic, and environmental assessment

In this study, three different types of solar thermal systems i.e. ETSC-A (lauric acid integrated with a hot water tank), ETSC-B (lauric acid integrated with hot water tank and palmitic acid with evacuated tube), and ETSC-Conv (without phase change materials) have been designed and fabricated. The energy performance of ETSC-A and ETSC-B compared to ETSC-Conv was found to be 30.94, 45.37, & 49.27 %, and 48.37, 76.36, & 57.88 % higher for ED-I, ED-II, and ED-III respectively. Concerning, techno-economic analysis, values of LCWH, NPV, and PBP for ETSC-B and ETSC-A in comparison to ETSC-Conv are found to be higher by 24.41 %, 26.44 % & 36.51 and 22 %, 24.36 % & 31.91 % respectively. About environmental scan, ETSC-B, and ETSC-A can mitigate more CO2 and generate revenue by almost 60 % and 41 % respectively than ETSC-Conv. The commercial deployment of developed systems specifically ETSC-B is not only advantageous in terms of thermal performance and economic viewpoint but also mitigates carbon dioxide emission.

Thermodynamic analysis of an advanced adiabatic compressed air energy storage system integrated with a high-temperature thermal energy storage and an Organic Rankine Cycle

Advanced adiabatic compressed air energy storage (AA-CAES) system has drawn great attention owing to its large-scale energy storage capacity, long lifespan, and environmental friendliness. However, the performance of the air turbine during the discharging process is limited by the low temperature of the compression heat. Thus, this study proposes an integrated AA-CAES system incorporating high-temperature thermal energy storage and an Organic Rankine Cycle (ORC). The high-temperature thermal energy storage is introduced to heat the discharging compressed air to enhance the air turbine performance, and the Organic Rankine Cycle is integrated to utilize the waste heat. Notably, two preheaters are deployed in a special tandem to recover the heat from the air exiting the turbine and the water exiting the hot water tank, respectively. This paper develops a thermodynamic model to simulate the proposed system, assessing the effects of heat storage temperature, ambient temperature, and inlet conditions of the air turbine on performance metrics, including exergy efficiency and exergy destruction. The simulation results indicate that, compared to thermal oil and Hitec salt, employing solar salt as the heat storage medium for the solar thermal collection and storage unit yields the best performance. The energy storage efficiency, roundtrip efficiency, exergy efficiency, exergy conversion coefficient, and energy storage density of this system are 115.6 %, 65.7 %, 78 %, 79.4 %, and 5.51 kWh/m3, respectively. Exergy analysis reveals that the exergy efficiency of interheaters (IH) is the lowest at 76.7 %, while air turbines (ATBs) exhibit the highest exergy efficiency at 91.2 %. Moreover, due to the irreversible processes of compression, expansion, and throttling, ATBS, compressors, and throttle valves collectively contribute to an exergy destruction rate as high as 79.2 %. The parameter analysis demonstrates that low ambient temperature, high inlet temperature, and high inlet pressure of the air turbine enhance energy storage performance.

Thermodynamic and economic analysis of a solar-assisted ejector-enhanced flash tank vapor injection heat pump cycle with dual evaporators

This paper proposes a solar-assisted ejector-enhanced flash tank vapor injection heat pump cycle with dual evaporators (SEFVIC), designed for heat pump drying application. Compared to the standard flash tank vapor injection heat pump cycle (FVIC), the SEFVIC uses an additional high-temperature evaporator to further minimize irreversible losses during the heat transfer process. Moreover, it integrates solar energy to improve the drying quality and heating capacity of the cycle. Meanwhile, the introduction of an ejector improves the system's performance by reducing throttling loss. The advantages of SEFVIC over FVIC are evaluated using theoretical models based on the first and second laws of thermodynamics. Results show that SEFVIC reveals a 34.1 % improvement in the heating coefficient of performance and a 192.8 % enhancement in volumetric heating capacity compared to FVIC under typical operating condition. Notably, SEFVIC maintains superior performance even at lower evaporating temperatures. Moreover, exergy research indicates that 77.1 % of the total exergy destruction in SEFVIC is attributed to the solar collector. Economic analysis indicates that the integration of solar energy into the SEFVIC is economically beneficial. These findings highlight the prospective application of SEFVIC and guide combining the multi-temperature heat pump drying system and auxiliary solar source.

Impact of trapezoidal ribs on the performance of solar air collector: A numerical solution with optimized rib dimensions for better performance

In the present study, a 2D numerical analysis of the solar air collector (SAC) of an indirect solar dryer having trapezoidal corrugations on the absorber plate was performed. Corrugation pitch, p (twelve values ranged from 20 to 160 mm) and height, e (six values ranged from 1 to 10 mm) were varied and analyzed for six values of Reynolds numbers (Re). The output characteristics such as Nusselt number (Nu), friction factor (f) and thermo-hydraulic performance index (Thp) were calculated for different p, e and Re. The total work was categorized into two parts (part-I for optimizing p and part-II for optimizing e). 18 domains (twelve for part-I and six for part-II simulations) were generated and 108 simulations were executed to find the optimum dimensions (p, e and corrugation angle, α) of the corrugation. ANSYS Fluent-v15 was used to solve the problem. The maximum Nu for the corrugated sheet was 2.663 times greater than the flat absorber plate. The maximum Thp range was from 1.435 to 1.699 and obtained at the optimal values of p = 140 mm, e = 4 mm and α = 38.66° The numerical results were compared with the existing literature.

Numerical study of hybrid nanofluid and thermal transport in sun-powered energy ship within the application of parabolic trough solar collectors

PurposeRecent advancements in technology have led to the exploration of solar-based thermal radiation and nanotechnology in the field of fluid dynamics. Solar energy is captured through sunlight absorption, acting as the primary source of heat. Various solar technologies, such as solar water heating and photovoltaic cells, rely on solar energy for heat generation. This study focuses on investigating heat transfer mechanisms by utilizing a hybrid nanofluid within a parabolic trough solar collector (PTSC) to advance research in solar ship technology. The model incorporates multiple effects that are detailed in the formulation.Design/methodology/approachThe mathematical model is transformed using suitable similarity transformations into a system of higher-order nonlinear differential equations. The model was solved by implementing a numerical procedure based on the Wavelets and Chebyshev wavelet method for simulating the outcome.FindingsThe velocity profile is reduced by Deborah's number and velocity slip parameter. The Ag-EG nanoparticles mixture demonstrates less smooth fluid flow compared to the significantly smoother fluid flow of the Ag-Fe3O4/EG hybrid nanofluids (HNFs). Additionally, the Ag-Ethylene Glycol nanofluids (NFs) exhibit higher radiative performance compared to the Ag-Fe3O4/Ethylene Glycol hybrid nanofluids (HNFs).Practical implicationsAdditionally, the Oldroyd-B hybrid nanofluid demonstrates improved thermal conductivity compared to traditional fluids, making it suitable for use in cooling systems and energy applications in the maritime industry.Originality/valueThe originality of the study lies in the exploration of the thermal transport enhancement in sun-powered energy ships through the incorporation of silver-magnetite hybrid nanoparticles within the heat transfer fluid circulating in parabolic trough solar collectors. This particular aspect has not been thoroughly researched previously. The findings have been validated and provide a highly positive comparison with the research papers.

Thermal transfer performance and flow instability analysis of direct steam generation for parabolic trough solar collectors

Parabolic trough solar direct-steam-generation (DSG) technology is the enabling technologies to achieve low carbon future. However, actual inlet boundary and flow boiling instabilities pose challenge to safe operation. In this paper, the coupled optical-thermal-flow pattern model for DSG loops is built utilizing conservation equations, separated flow model and Lagrangian method. The heat transfer performance, hydrodynamic characteristics and two-phase flow law of the loop are discussed under the coupled variation of direct radiation intensity (DNI), mass flow (m), inlet temperature (Tin) and inlet pressure (Pin). The correlation between multi-condition, thermodynamic characteristics and flow instability is analyzed. The results show that increasing Pin, Tin and DNI have almost no effect on the intermittent state. The percentage of annular flow only remained stable (about 84.8%) when the steam mass was 1. Increasing DNI and Tin did not effectively improve the flow heat transfer, while increasing Pin worsened the flow heat transfer and increased the probability that the annular flow would turn into stratified flow but could reduce the pressure drop and the fluid vapor-liquid density difference and stabilizes its hydrodynamic properties. The simultaneous increase in m not only weakens this effect and strengthens the heat transfer, but also permanently reduces the probability of stratified flow. The higher the Pin, Tin and DNI, the lower the flow instability of the DSG system. Manual operation is recommended to prevent the system having flow instability in the morning due to the lower solar radiation intensity and inlet temperature when the system is started in the morning.

Thermal performance investigation of rhombus shape roughened solar air collector- A novel approach

Current study investigates parametric study on thermal performance of a rhombus-shaped artificially roughened absorber plate (RAP) used in solar air collector. Experimental investigations were performed in month of April–May 2024 in mechanical department of MANIT, Bhopal. Relative roughness pitch (P/e), relative roughness height (e/Dh), number of elements (W/Vr) and relative diagonal length (dr/e) in the range of 8–12, 0.0225–0.03375, 9–11, and 8–12 respectively are used as geometrical parameters for current study. Reynolds number (Re) is varied from 2000 to 14000. Thermal efficiency (ղth) is reported in terms of collector heat removal factor (FR), and collector efficiency factor (F′). A significant enhancement in ղth has been observed, ranging from 1.42 to 1.63 times higher when compared to the performance data of smooth plates. Maximum ղth of 79.48% was found at P/e = 10, e/Dh = 0.03375, W/Vr = 10, dr/e = 9.6 at mass flow rate (m˙) = 0.031 kg/s. Collector's performance parameter are reported as (FRτα) and (F0UL). value of (FRτα) and (F0UL) is reported 0.8612 and 15.82 for rhombus shape at optimal geometrical parameters.