Solar Absorber Plate Research Articles

Analysis of Implication of Phase Change Material Enclosed Design on Thermal Performance of Solar Collector

Abstract The energy, which is converted from the sun rays, was called solar energy. This is very essential renewable energy converting methods that had a higher influence for water distilling system. Here, the implication of the Phase Change Materials (PCM) in that exit was analyzed. This energy from the sun is trapped in paraffin wax for the storing system whiles the greater radioactive effect. This trapped heat power than utilized for increase the fluid temperature during the lesser radioactive times. Here, the Implication of the heat storing units on the exit temperature was analyzed. Furthermore, Thermal solar collector was analyzed for the following years 2021 and 2022. The Concentric PC is placed over the top of the collector of the solar rays. And then, a paraffin wax layer was placed under the solar absorber plate like the back-up to store the LH Energy. The uniform rate of flow was produced a greater exit temperature of water the two years. The efficiency rate increased 11–14% and the collected energy gain rate enhanced 18–19%. The peak water temperature was 61°C & 60°C for the 2 consecutive years for Paraffin wax integrated solar collecting unit. At the same time the efficiency of heat energy is peak at 49% in January 2022. The solar collector efficiency primarily relies on the design and construction of collector itself.

Experimental analysis of solar desalination system performance with graphene and graphitic carbon nanopaint-coated solar absorbers

Improving the efficiency of basin-type solar stills is crucial for ensuring reliable access to clean water in areas facing water scarcity. One effective way to increase water yield production is by applying various coatings to the solar still's absorber plate. Using nanocoatings on solar absorber plates increases solar radiation absorptivity and minimizes reflectivity, which helps improve water production. In this proposed work, Graphene nanoplatelets (GNPs)-based nano paint, graphitic carbon nanoparticles (GCNPs)-dispersed black paint, and conventional black paint were applied to the solar still's absorber plate. According to the study, the GNPs' nano paint resulted in a cumulative solar still productivity that was 48.23 % higher than the GCNPs-dispersed black paint and 10.28 % higher than the conventional black paint. It also revealed that the energy efficiency of solar stills with GCNPs and GNPs nano paint-coated absorbers was 56.96 % and 69.77 %, respectively, while the traditional black paint-coated absorber managed only 39.42 %. The calculated exergy efficiency of these three solar stills was 8.55 % for the conventional black paint, 13.93 % for the GCNPs, and 22.93 % for the GNPs nano paint-coated absorber. This proposed system also has an energy payback period of 1.79 years and contributes to achieving a carbon credit of $994.90 through the market. The cost of distilled water in this system is also 0.016$/L.

Investigation on energy, economic, and environmental aspects of double-pass solar air heater.

Numerous research studies have found that a double-pass solar air heater (DPSAH) performs better than a single-pass solar air heater (SAH). This suggested study aims to evaluate the performance of a DPSAH setup in Southern Tamil Nadu, India. Several artificial roughness features have been incorporated into the solar black-coated absorber plate for this examination. Broken ribs with semi-circular and semi-polygonal shapes are used and explicitly tested on the absorber plate. Next, the efficiency of these rib designs is contrasted with a typical flat plate DPSAH. These studies also employ three different mass flow rates (0.01kg/s, 0.02kg/s, and 0.03kg/s), enabling a thorough assessment of the DPSAH system's performance at each rate. These studies' findings demonstrate that adding artificial roughness to the solar collector plate has a beneficial effect on the turbulence of fluid flows. As a result, this innovation increases the double-pass solar air heater's (DPSAH) heat transfer rate. It is noteworthy that compared to the DPSAH with flat plates, both rib designs perform better. It is important to remember that the semi-polygonal ribs function better than the semi-circular ones. The average efficiency values for the semi-polygonal rib structure are 17.1%, 18.7%, and 19.1% greater than those seen for flat plates. These efficiency values are additionally 4.4%, 7.4%, and 8.7% higher than those attained with the semi-circular rib topologies at flow rates of 0.01kg/s, 0.02kg/s, and 0.03kg/s, respectively. The study goes into considerable detail on how particular rib patterns can be advantageous economically and environmentally.

Design, construction and performance evaluation of paddy rice solar drum dryer equipped with perforated drum

Abstract A solar drum dryer was designed and constructed for paddy drying, including a fixed outer drum and inner perforated drum, which rotated at the desired rotational speed inside the outer drum. The maximum capacity of the dryer was 10 000 g. The rotational speed of the inner drum was controlled. The thermal energy required for the dryer was provided by a solar absorber plate. The dryer performance was examined at three levels of rotational speed (0.21, 0.42 and 0.84 r.p.m.), drum slope (1°, 1.5° and 2°) and air velocity (1.7, 1.8 and 1.9 m.s−1). The diameter of the drum was the geometrical parameter that affected the movement of the particles and the ratio of the particle diameter to the drum diameter changed with the change in the drum diameter. Therefore, increasing the diameter of the drum caused a reduction in the repose angle of the paddy without any effect on the filling angle. The displacement of the product along the drum increased with increasing slope and rotational speed. At the lowest air velocity, the time required to remove moisture (<13%) was less. The results showed a significant reduction in cracked brown rice for the paddy dried by the drum dryer at 43–46°C compared with those dried using a batch dryer. The highest stress-cracking index (11) was observed for the paddy with an initial moisture of 16%. The results showed that for proportional final moisture content, a longer drum should be considered to intensify the slope and rotational speed of the inner drum.

Semi-analytical technique for the design of disordered coatings with tailored optical properties.

Disordered media coatings are finding increasing use in applications such as day-time radiative cooling paints and solar thermal absorber plate coatings which require tailored optical properties over a broad spectrum ranging from visible to far-IR wavelengths. Both monodisperse and polydisperse configurations with thickness of coatings up to 500 µm are currently being explored for use in these applications. In such cases it becomes increasingly important to explore utility of analytical and semi-analytical methods for design of such coatings to help reduce the computational cost and time for design. While well-known analytical methods such as Kubelka-Munk and four-flux theory have previously been used for analysis of disordered coatings, analysis of their utility has so far in literature been restricted to either solar spectrum or IR but not simultaneously over the combined spectrum as required for the above applications. In this work, we have analysed the applicability of these two analytical methods for such coatings over the entire wavelength range from visible to IR, and based on observed deviation from exact numerical simulation we propose a semi-analytical technique to aid in the design of these coatings with significant computational cost savings.

Effect of Base Angle of an Isosceles Trapezoidal Solar Air Heater Duct on Flow and Thermal Characteristics—A Numerical Investigation

Abstract This paper reports the computational results of fluid flow and thermal characteristics in an isosceles trapezoidal solar air heater (SAH). By varying the base angle of the trapezoidal duct from 90 deg to 45 deg, six different models of solar air heater ducts are obtained. The six geometries of SAH ducts have cross sections of rectangular (90 deg), triangular (45 deg), and four isosceles trapezoidal (having base angles of 50 deg, 60 deg, 70 deg, and 80 deg) shapes. The solar radiation absorber plate width and the duct heights are maintained constant for all six models of SAH, i.e., 160 mm and 80 mm, respectively. The SAH is subjected to a constant and uniform heat flux value of 1000 W/m2 and Reynolds numbers varied from 5000 to 28,000. In all six cases, the size of the air heater is the same and having dimensions of 0.16 m width and 1 m length. For this investigation, a three-dimensional computational model has been developed and simulations are carried out using commercially available ansys fluent software. The numerical results are validated with the standard correlations and literature data, and a suitable model has been identified for the turbulence closure. A detailed analysis of the Nusselt number, temperature distribution over the SAH, and friction factor across the SAH duct is done. Empirical correlations for the estimation of heat transfer and friction factor have been developed as functions of the base angle of the duct and Reynolds number. An overall performance factor (λ) is adopted to get the combined effect of friction factor and Nusselt number with an intention to arrive at the optimum base angle of the SAH duct, and optimum geometry is identified. Based on the value of λ, it is concluded that the SAH duct with the highest base angle (90 deg) in this investigation, i.e., the rectangular duct, is the optimum among all the ducts considered in the study.

Computational fluid dynamics simulations of solar-assisted, spacer-filled direct contact membrane distillation: Seeking performance improvement

Significant downstream performance reduction and concentration polarisation reduce direct contact membrane distillation (DCMD) efficiency. These challenges are not well researched since they are difficult to implement experimentally and numerically. Hence, this study examined the impact of solar absorbers and different spacer filaments upon DCMD performance. A 2D computational fluid dynamics model that considered simultaneous mass and heat transfer across the membrane and throughout the channels was developed to simulate water flux in DCMD modules under the use of solar absorbers and spacer filaments of various designs. The simulation outcomes were in excellent agreement with experimental results provided by two different studies, with the assisted solar absorber module and the spacer-filled module deviating <5 % and 3 % from the experimental results, respectively. A module equipped with the solar absorber membrane enhanced the DCMD performance better than a module with a solar absorber plate. The results also illustrated that a module with cylindrical detached spacer filaments improved DCMD performance more than a module with rectangular and semicircular attached spacers. Finally, it was shown that a module equipped with an integrated developed spacer and solar absorber membrane significantly enhanced water flux and both concentration and temperature polarisations, specifically when the inlet velocity was increased. Water flux and the temperature polarisation coefficient increased by 220 % in the integrated module, and the concentration polarisation coefficient decreased by 10 %. Moreover, the developed module resulted in a substantial increase in downstream performance.

Heat transfer enhancement of solar collector by placing wire mesh stainless porous material on the solar absorber plate of indirect forced convection solar dryer

Indirect forced convection solar dryers are a common technology in solar drying. The flat plate solar collector is an essential device that absorbs heat from solar radiation in order to heat the air flowing through. To improve the thermal utilization of this device, heat transfer enhancement by using the technique of changing airflow patterns into swirling or rotating flow was proposed in this research. In the experiment, wire mesh stainless porous material (WP) SUS304 with various porosities (X) of 0.747, 0.888 and 0.928, transverse pitch with duct height ratio (P/h) of 1.14, 1.43, and 1.71, rib height with duct height ratio (R/h) of 1, attack angle (α) of 30° was placed on the solar absorber plate and the investigation conducted under solar simulator of EN 12975–2 standard with a constant solar intensity of 780±20 W/m2. Air was used as the working fluid in the turbulent flow region at Reynolds number (Re) in the range of 3,700–30,000. The experiment results showed that Nusselt number (Nu), Friction factor (f) and Thermal enhancement factor (TEF) significantly increased when WP was placed on the absorber plate because the swirling airflow through WP occurred and disturbed the thermal boundary layer on absorber plate. The increase in Re resulted in increased Nu and decreased f. Nu and f increased with a decrease in X and P/h. The highest Nu and f of 303.01 and 5.14, respectively, were found at X = 0.747 and P/h = 1.14. The maximum TEF was 1.84. Besides, the developed correlations were in good agreement with the experimental results of predicting both Nu and f with the mean differences of 6.23% and 9.98%, respectively.

Thermal behavior of natural convection flow in an inclined solar air heater

The thermal behavior of hot air in a natural convection mode on a solar absorber-plate has not been, so far, modeled experimentally. The present work aimed to assess the performance of the inclined solar air heater [SAH] experimentally by investigating the temperature distribution field in the natural convection flow. The solar plate collector is designed based on the aspect ratio of length to height, L / H, of 6 and 12. The measurements are carried out for the collector tilt angles of 30°, 45°, 60° and 75°. The present investigation demonstrates the temperature distribution of hot air floated in an inclined channel of the SAH. The investigation showed 2D thermal stratification increases when increasing the distance along the collector plate, which looks clear in the SAH with a height of 10 cm. The results of the study show that the thickness of the thermal layers increases with increasing the tilt angle from 30˚ to 75˚. The reason dates back to increasing the buoyancy force of the hot air over the absorber. The results demonstrated that the air temperatures for the height of 0.1 m and 45˚ tilt angle are higher than that for the height of 0.2 m by 23%.

Effect of nano cupric oxide coating on the forced convection performance of a mixed-mode flat plate solar dryer

In this study, mixed mode solar dryer of forced convection type, integrated with a CuO nanoparticle coated flat plate solar collector was developed and its effectiveness of drying maize under the meteorological conditions of Coimbatore, India was evaluated. The aforementioned setup entails a solar collector (flat plate type) with 3 drying trays and a centrifugal blower. The conventional solar absorber plate was made up of aluminium, which was coated with black paint. Another modified solar absorber plate was made up of aluminium with a coating of black paint with two different vol% of CuO nanoparticles (0.02% and 0.04%), for improving the heat transfer rate. Performance tests on the modified dryer were carried out at constant air flow rate (1.5 m3/min) and the results were compared with the conventional type. The efficiency of the collector got improved by 4% while using black paint with 0.04 vol% of CuO nanoparticle coated absorber. Also the drying time got reduced by 6%, when compared to conventional type dryer. Also the collector temperature recorded in the black paint with 0.04 vol% CuO nano-particle coated collector was higher compared to black paint coated and black paint with 0.02 vol% CuO nanoparticle coated collector.

Thermal Performance Analysis of Solar Air Heater Having Rectangular Rib Configuration Using Numerical Modeling

The aim of present research paper is to show the effect of solar air absorber plate design change using CFD modeling software. In this present work full year simulation is performed for simple solar air heater then different velocity conditions are compare with improved design of solar air heater. Experimental validation is also performed for this research work. Ansys fluent software is used for this research work. All filed experiments are performed at Jaipur. Improved design solar air heater show 20% efficiency improvement then simple solar air heater. In present era, electrical energy is most valuable product for human technological improvements. The generation of electrical energy is depend on conventional energy sources like coal, petroleum products, natural gas etc. But these source depleting continue from previous years. So it is requirement for searching new infinite energy sources, which help to generate electrical energy for human development. The most important research in this field is PV based electrical energy generation. The solar air duct is fabricated and simulated for optimization of this solar air heater used in this research work. CFD simulation is carried out using Ansys Fluent Software. Seasonal effect, flow boundary conditions and extended surfaces are investigated in this research work. The final conclusion of this research work is that extended surface can improve the performance of this device.

Geometrical optimisation of Transpired Solar Collectors using design of experiments and computational fluid dynamics

Transpired Solar Collectors (TSCs) are simple low maintenance air heating systems which have been widely used for agricultural and industrial applications. In spite of their potential, these systems have not been yet widely employed in residential buildings as they are unable to generate high grade heat for moderate and low ventilation demands. Hence there is an opportunity for optimisation studies in order to enhance the thermal performance of these systems.Optimisation and parametric studies can be costly and time consuming if carried out by physical experiments. CFD models however offer a more flexible and less expensive tool to carry out such studies. This research has aimed to optimise the geometry of the solar absorber plate using a validated CFD model which accounts for a wide range of the key factors affecting TSC performance.A 2nd order polynomial predictive model was developed based on the CFD results with Root Mean Squared Error (RMSE) of 3.8%. The predictive model was used to identify an optimal geometry which delivers a Heat Exchange Effectiveness (HEE) of 0.739. The optimised geometry demonstrated 43% increase in HEE whilst using 28% less material compared to the baseline geometry under the same operating conditions. This geometry can be integrated with other performance enhancement techniques to further improve the thermal performance of TSCs.

Solar air collector with the solar absorber plate containing a PCM – Environmental chamber experiments and computer simulations

The influence of latent heat thermal energy storage integrated with the solar absorber plate was investigated through lab experiments and computer simulations. Two experimental solar air collectors were built. One collector had the solar absorber plate made of sheet metal while that of the other collector consisted of nine aluminium panels containing a paraffin-based PCM. The square-wave variation of the solar radiation intensity was considered, and a good agreement was observed between the computer simulations and experimental data. The peak-to-peak amplitudes of the outlet air temperature were reduced from 11 K (the collector with the metal sheet absorber) to 5 K (the collector with the absorber plate containing the PCM). The main contribution of the study consists in the experimental approach and in the validated model of the solar air collector for TRNSYS simulation tool. The experiments were conducted in an environmental chamber fitted with a solar simulator under both the quasi steady-state and the transient boundary conditions. In comparison to other studies with experiments conducted outdoors, the controlled environment of the climatic chamber allowed for the reduction of the uncertainty on the side of the boundary conditions, e.g. the influence of wind speed, wind direction, and cloudiness.

AUTOMATED MEASUREMENT AND SYSTEM DATA LOGGER FOR CONTINUOUS MONITORING OF SLICED BANANA FRUIT DURING DRYING PROCESS BY A SOLAR HOT- AIR DRYER

The aim of this work is developing and evaluating an automated measurement and system datalogger for continuous monitoring of solar hot air drier for natural convection solar cabinet drier. Measurements includes monitoring of drying process for sliced Banana (Musa acuminata) relation to weather parameters such as ambient air temperature, relative humidity and wind velocity which ensures precise measurements and reproduction of experiments. An electronic measurement system was used for measurement of temperature, humidity, air speed, a solar intensity. A programmable microcontroller ship and code were used to control measurement, timing, and data storage twenty-four hours/day. All measurements data was collected and saved in storage memory card. Results showed that the solar drier drying rate achieved (-0.018gH2O/g dm.h), while the drying rate with mean of electrical thermal drier were (-0.956 018gH2O/gdm.h) at 105°C, (-0.552 018gH2O/g dm.h) at 70°C and (-0.513 018gH2O/gdm.h) at 50°C. The electronic measurement - datalogging system was able to give an accurate measurement and assessment to the drying system and process. It was found that air leakage from the system and poor insulation inhibit the airflow over the solar absorber plate and drying chamber causing thermal leakage form the bottom and drier sides. It was recommended to supply the solar drier with an air fan, seal the drying air leakage, and air-lock at the entrance to control airflow as well as the temperature of the drying process.

Microstructural analysis and optical properties evaluation of sol-gel heterostructured NiO-TiO2 film used for solar panels

In this study, the production, microstructural characterization and optical properties evaluation of heterostructured NiO-TiO2 films were performed. The film is intended to be used in solar cell applications. Ni-P electroless film was made on an AA7050 aluminum alloy. The film was black nickel electrodeposited by diluted nitric acid and then a thin TiO2 layer coating was deposited by Sol-gel process. The microstructure of the film was analyzed by scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS) detector. X-ray diffraction (XRD) technique was used to determine the phases formed in the heterostructured film. Optical properties of the heterostructured film were measured by UV–visible spectroscopy and photoluminescence (PL) Test. Results showed that the heterostructured NiO-TiO2 films had a cauliflower characteristic and was amorphous crystallographically. The heterostructured films also increased the absorption coefficient of the solar absorber plates up to more than 98% in the visible-ultraviolet range. Finally, it was shown that, in the infrared region, the absorption coefficient for dispersion was down to 2%.

A hybrid PV/T solar evaporator using CO2: Numerical heat transfer model and simulation results

This paper investigates a new geometry of hybrid photovoltaic/thermal (PV/T) solar collector used as an evaporator in a CO2 transcritical heat pump system. The solar absorber plate embeds monocrystalline silicon PV cells producing electricity and a stainless steel sheet to improve heat transfer with respect to standard back sheets. A serpentine stainless steel tube is bonded to the back of this solar absorber plate and two-phase CO2 flows inside this heat exchanger.A semi-transient numerical model is proposed to assess the thermal and electrical performances of the evaporator under given weather parameters and heat pump operating conditions. The 2-D, transient thermal diffusion equation is combined with a 1-D, steady state, compressible, two-phase flow model to compute the temperature distribution of the solar absorber plate along with the pressure, velocity, density and enthalpy field of the CO2 in the serpentine tube. A special model based on the straight fin analytical model accounting for the circumferential temperature gradient around the tubes is developed to combine the absorber plate and the heat exchanger models.The simulation results show an overall mean temperature reduction of the solar absorber plate operating at an electrical maximum power point of more than 25 °C with respect to a standard PV collector. Reducing the plate temperature leads to an additional production of 34 W of electrical power exceeding the maximum power specified under the test conditions of IEC 60904-3 international standard. In the simulated conditions, 1.028 kW of thermal power is also extracted and can be used in heating applications. The electrical efficiency increases from 14.1% for a standard solar PV collector to 16.0% for the suggested evaporator design. Finally, an overall efficiency combining both the electricity and heat production of 72.3% is achieved.

Comparison of the Energy Conversion Efficiency of a Solar Chimney and a Solar PV-Powered Fan for Ventilation Applications

A study into the performance of a solar chimney and a solar photovoltaic (PV)-powered fan for ventilation applications was carried out using numerical simulations. The performance of the solar chimney was compared with that of a direct current (DC) fan powered by a solar PV panel. The comparison was carried out using the same area of the irradiated surface—the area of the solar absorber plate in the case of the solar chimney and the area of the solar panel in the case of the photovoltaic-powered fan. The two studied cases were compared under various solar radiation intensities of incident solar radiation. The results indicate that the PV-powered fans significantly outperform solar chimneys in terms of converting solar energy into the kinetic energy of air motion. Moreover, ventilation with PV-powered fans offers more flexibility in the arrangement of the ventilation system and also better control of the air flow rates in the case of battery storage.

Transient computational fluid dynamics investigations on thermal performance of solar air heater with hollow vertical fins

Evaluation of experimental thermal performance of a single pass solar air dryer is compared with a transient CFD studies is performed. Vertical hollow plates are placed below the absorber plate and compared against the flat solar absorber plate for its performance improvement. Effect of mass-flow rate, the outlet temperature of air is computationally analyzed in comparison with the experimental work, transient boundary conditions for CFD like ambient temperature, solar insolation are taken from the experimental work, and computational results are in good agreement of with experimental results with maximum error percentage of 10%. Thermal efficiency was increased with increase in mass-flow area for without fin configuration, for a specific mass-flow rate thermal efficiency had a good improvement with fin configuration than the without fin configuration.

A 2-D transient numerical heat transfer model of the solar absorber plate to improve PV/T solar collector systems

This paper presents a genuine 2-D transient numerical model to evaluate the temperature field and the dependent electrical performances of different solar absorber plates. It can readily be adapted for solar thermal absorber plates, standard PV plates or thermally enhanced PV plates that can be used in PV/T solar collectors. The model can also be combined with the appropriate heat exchanger equations to simulate a complete solar collector. A simple optical model is combined with the well-known five parameters PV module electrical model and the 2-D heat conduction equation to compute the temperature field of the PV plate and the electrical power generated for every time step of the simulation. The resulting differential equation is solved through finite volume discretization using an implicit time discretization scheme. The model relies on widely available weather parameters such as total horizontal solar radiation, ambient temperature, wind speed, etc. Validation of the electrical model is first carried out in real outdoor weather conditions comparing simulated and measured electrical current. During this process, measured temperature of the plate and incident solar radiation are used as inputs. Then, the global multi-physic model is validated using a temperature measurement at a selected point and the measured electrical performances. In the multi-physic model, measurements of the incident solar radiation, air temperature, wind speed and relative humidity are used as inputs. The validation results for the temperature showed a maximum discrepancy of the numerical predictions with respect to the measurements of less than 2 [°C] and a discrepancy below 7 [%] for the electric power production both over a complete day of simulation.

Low-temperature solar-plate-assisted heat pump: A developed design for domestic applications in cold climate

Solar energy and wasted heat in buildings are capable of supplying enough energy to answer the total demand of energy in dwellings. However, fluctuation in fuel prices and gas emissions are the main driving forces behind efforts. In this experimental study, a direct expansion solar-assisted heat pump system (DX-SAHP) using a bare ternary “retrofitted collectors with black paint” is investigated at the laboratory with a solar simulator and tested for domestic hot water (DHW) and space heating under quasi-static conditions. Unglazed solar collector absorber plates are used as an evaporator, and these are composed of two aluminium plates which are placed externally whilst another plate is mounted internally in the loft space of the house, where operating liquid from the heat pump is directly evaporated. The influence of outside temperature, solar irradiation and/or waste heat on the heating performance of DX-SAHP is investigated. The impact of the parameters such as the inlet temperature and the mass flow rate of the heat transfer fluid is also assessed. Preliminary results elucidate that the refrigeration cycle can be a promising substitute for space heating and hot water when compared to the heat pump systems. This design technique results in higher solar collector/evaporator efficiency and lower system losses due to low evaporating temperature.