Thermal Performance Of Solar Collector Research Articles

Impact of absorber surface coatings on the thermal performance of non-concentrating solar thermal collectors: An overview

In this critical evaluation, the impact of absorber surface coating on the thermal efficiency (%) of non-concentrating solar thermal collectors (STCs) is examined and discussed. Absorber surface coatings enable an almost instantaneous conversion of solar radiation into heat. To achieve high sunlight absorption capacity and low solar emittance, several types of selective solar coatings are continually being developed. This review article offers a novel aspect based on extensive research that has been published in the past related to the impact of absorber surface coating on the thermal performance of non-concentrating STCs. The article demonstrates the commonalities in the results by thoroughly evaluating all the coating types that have the potential to influence STC's performance. An exhaustive examination of the available research from several studies shows that absorber surface coating enhances the STC absorber's capacity to absorb heat.

A comprehensive review of the influence of nanomaterials on the thermal performance of a solar thermal collectors

The present review article investigates the utilisation of nanomaterials with the aim of augmenting the thermal efficiency of solar thermal collectors (STCs). A comprehensive analysis is conducted on the STC through the utilisation of nanomaterials, leading to an improvement in its performance. This evaluation highlights the similarities in the results through an in-depth discussion on several types of criteria that might impact the performance of STCs. In order to justify and, finally, explain the behaviour of nanomaterials for the purpose of thermal augmentation of STCs, analysis was carried out and is being discussed here. This review article presents a novel aspect that is based on an extensive investigation that was based on a significant amount of research that had been published in the past. The study indicated that the use of nanomaterials may boost the heat-absorbing ability of the STCs.

An experimental investigation of the thermal performance of solar collectors utilizing finned aluminum can pipes

An innovative experimental study is presented to improve the performance of solar collectors designed for solar drying systems, focusing on the use of recycled aluminum can waste and the development of the air solar collector. The latter’s absorber is made up of 10 cans with a diameter of 65 mm, a length of 160 mm and a thickness of 0.3 mm, forming a cylindrical finned pipe. Several collector configurations under identical weather conditions, including four collectors with different rows of rods (4, 8, 12–14 rows) and a single collector, were analyzed and compared. The thermal performance of this new collector model was assessed on the basis of solar fluxes and collector inlet and outlet temperatures, collected during the month of September 2021. Experimental results revealed that this collector can increase the outlet temperature of air from 32°C up to 130°C, in the case of a 14-row collector. The study also showed that, at low flow rates, the can-equipped collector achieves an efficiency of 54% for the case of a 14-row collector, compared with 34% for the simple case, representing a 20% improvement over the single case. The study also showed that, at low flow rates, the can-equipped collector achieves higher outlet temperatures.

Performance Improving for the Flat Plate Solar Collectors by Using Nanofluids: Review Study

In this paper, the literature will be reviewed, and various research works conducted to improve the thermal performance of flat panel solar collectors will be summarized. It will be summarized in more than one way. Firstly, by design using different methodologies and methods to improve the efficiency and the thermal performance of the solar collector by introducing twisted strips that cause increased mixing. Fluids and Friction for FPSCs. To increase heat transfer as well as use porous materials to enhance heat and improve the effectiveness of absorption panels to absorb as much solar radiation as possible as well as thermal insulation methods to reduce losses to surrounding areas. And improve the permeability of the glass cover. Secondly, the use of nanofluids enhances the performance of flat solar collectors instead of the core fluid, and its effect is to improve the thermophysical properties such as thermal conductivity by summarizing previous research using mono nanofluids and hybrid nanofluids. Through studies and research related to the use of mono nanofluids, it was noted that the best nanofluids are those that use CuO and Al₂O₃ particles due to their ease of availability and high thermal conductivity. As for hybrid nanofluids, the best fluids are (CuO + Al₂O₃/water) for the same reason above. As a result of design improvements and the use of nanofluids, temperatures up to (75C°) were obtained.

Enhancement and experimental study on thermal behaviour of heat pipe based solar absorber by using CuO nanofluid

Technological growth in thermal science found that the awareness of solar thermal energy improved widely in various applications and spotted issues on conventional flat plate solar collectors operating with water fluid: lower thermal efficiency, limited thermal performance during low sunlight, and unavoidable heat loss for extended plate surface. This research attempts to enhance the thermal performance of solar collectors modified with heat pipe solar absorber (HPSA) evaluated by 0.010, 0.015, and 0.02 volume fractions of CuO nanofluid at 18 Lpm. The effect of CuO on varied flow rate on temperature gain, heat transfer coefficient, and thermal efficiency of HPSA is experimentally studied, and its findings are compared with water fluid. The HPSA operates with 0.015 volume CuO nanofluid with a higher rate of flow, proving better thermal performance and offering a maximum temperature gain of 68?C with a better heat transfer coefficient of 81.5W/m2K results enhanced thermal efficiency of 85.2%, which are higher than the water fluid operated HPSA system. An optimum operating parameter of HPSA is suggested for heat exchanger applications.

Анализ тепловой производительности радиационной системы жизнеобеспечения на основе экспериментальных данных

Solar energy is considered a renewable, most environmentally friendly and carbon-free form of energy. Solar collectors are one of the implementations of radiation life support systems. Their development requires a fairly large amount of initial data, such as the parameters of the premises, the required temperature, volume, thermal insulation of walls, floors and ceilings, the design of windows and doors, orientation to the cardinal points, the angles of inclination of the roof slopes, etc. The next group of factors is related to the location object, latitude, altitude above sea level, distance to large bodies of water, wind rose, etc. The third group is related to the weather itself: precipitation, cloudiness, outside air temperature, etc., a significant part of them, such as fog, haze, dew, shadow from each cloud affects the amount of insolation and all this cannot be taken into account in advance. The use of weather archives does not allow us to fully determine the specific thermal performance of solar collectors, since neither the average nor the current insolation is reflected in the archives. Without knowing the amount of real insolation and heat losses on the solar collector, it is impossible to determine the thermal performance of the radiation life support system per day, month, season or year. This paper discusses experimental and computational studies of the radiation life support system carried out in 2018–2022.

Optimization of Geometrical Parameters of a Solar Collector Coupled With a Thermal Energy Storage System

Abstract Solar thermal collector is a device that converts solar radiation into useful thermal energy (heat). This technology has become mature and cost-effective. However, because its input comes from an intermittent source (sun), its production is variable during the day; also it is vulnerable to climatic conditions. To adopt this technology, it is therefore necessary to invest in energy storage means or to use a secondary energy source. In this work, a solar thermal collector has been studied and modeled. The objective of this study consists of: first, analyze the impact of the geometrical form of the absorbing surface on the solar collector's thermal performance. Three geometries are tested, namely flat, triangular, and corrugated. The solar collector is evaluated under a hot climate considering the meteorological data of Er-rachidia city (Morocco). The second part of the present study consists of integrating a latent heat storage system using phase change materials (PCMs) to store part of the heat and exploit it during the night. Integrating PCM in this system is a relevant technique to overcome the problem of intermittency of solar energy. Moreover, according to the findings of this study, a significant improvement of the solar collector thermal performance has been reached. The reduction of the missed thermal energy is from 5.6485 kW h to 4.4566 kW h with the use of PCM and the corrugated surface.

Experimental investigation of thermohydraulic performance of solar thermal collector for sustainable built environment

Solar heating is a low-cost option for heating buildings, which help in the development of a sustainable built environment as it can fulfil the building heating demand. For this purpose, solar air heater (SAH) can be employed, however, insignificant performance of a typical solar air heater (SAH) restrict its applications for warming a building. Artificial roughness is the most promising way to enhance the significant performance of SAH. In this regards, novel artificial rib roughened absorber surface has been proposed and design in such a way to improve the heat transmission capability without any adverse effect. With this aim, gaps in multi open trapezoidal ribs (MOTRG) are introduced to take the benefit of secondary flow to be released through gaps concerning to high rate of convective the heat transmission and release of the enough pressure leading to low friction factor. The SAH with proposed MOTRG has been scrutinised experimentally. The distinct roughness parameter of the proposed rib configurations such as relative rib height (e/Dh = 0.023–0.054), relative gap width (g/e = 1–5), relative limb length (L/w = 0.2–1.0), relative roughness pitch (p/e = 6–12), relative width ratio (W/w = 6) and angle of attack (α = 60°), have been encompassed and tested for the Reynolds number (Re = 2000–16000). It has been noted that rib gaps significantly improved the Nusselt number (Nu) and marginally reduced the friction factor. As results, range of thermohydraulic performance has been discovered to be 3.40 to 3.99. The mathematical correlations of Nu and friction factor induced by the MORTG have been formulated as function of flow and non-dimensional roughness parameters.

A comprehensive review on the application of nanofluids and PCMs in solar thermal collectors: Energy, exergy, economic, and environmental analyses

BackgroundSolar energy is broadly utilized in various applications, including solar thermal collectors (STCs), heating, desalination, etc. The SCs are employed to convert solar energy into thermal one. Utilizing nanofluids (NFs) and phase change materials (PCMs) can improve the performance of STCs by enhancing the rate of heat transfer. MethodsThe present review paper describes NFs and PCMs, explains STCs, and provides different advances in these subjects. The influences of NFs and PCMs on the performance of STCs are examined. In addition, energy, exergy, economic, and environmental considerations are evaluated, and finally, current challenges and future directions are discussed. Significant findingsIt was observed that the use of NF and PCM leads to a significant improvement of the energy and exergy functions of STCs. Also, Also, it was found that a limited number of studies have been done on the performance of NF-based STCs from an economic and environmental point of views, and all of them have reported the positive effect of NFs on the performance of these systems. Moreover, it was revealed that the employment of NFs in the STCs depends on their long-term stability and preparation costs. Therefore, more laboratory investigations are required to characterize thermophysical properties of NFs.

Effect of novel phase change material (PCM) encapsulated design on thermal performance of solar collector

Solar energy is one of the renewable energy sources that has a great potential for water heating system applications. In this work, the effect of the PCM on the outlet water temperature was studied. The solar energy is collected in the phase change material (PCM) by the storage unit during the higher radiation hours. The collected thermal energy then used to heat the water during the lower radiation hour. In this work, the effect of the PCM on the outlet water temperature was studied. Furthermore, the performance of consecutive two years (2018 and 2019) of thermal solar collector was investigated. The compound parabolic concentrator (CPC) was positioned on the upper surface of the thermal collector. Moreover, a thin layer of PCM was positioned under the absorber plate as a back layer for the storage of the collected latent heat. A constant flow rate was obtained at maximum outlet water temperature for those consecutive years. Additionally, a relatively steadier decrease of solar efficiency at lower solar radiation was also evident on the PCM system compared to that of the system without PCM thin film. The efficiency of solar collector depends on the design of solar collector and our proposed design was able to extract a prospective thermal efficiency for two consecutive years of observation. These outputs are satisfactory and acceptable for long-term applications for both domestic and industrial purposes.

Effect of surface treatments on absorptance and morphology of molybdenum and silica absorbing thin films

The thermal performance of solar collectors depends on the selective coverage over their absorbing plate, known as selective surfaces, which determines the heat gain and loss of the equipment. Different materials and layering arrangements can be used for the production of selective surfaces. This work proposes the production of selective surfaces of molybdenum (Mo) and silica (SiO2) evaluating the influence of the type of substrate treatment (chemical cleaning, passivation and electropolishing) on this performance. The results obtained in UV–Visible and Near Infrared Spectrophotometry showed that the surface absorptance is higher for Mo and Mo/SiO2 films on electropolished surfaces compared to treatments with acid and hexane. The highest absorptance reached was 98.10% for a Mo/SiO2 film (45.023 nm), on electropolished substrate. However, the highest solar selectivity was obtained from the Mo/SiO2 film on a passivated substrate. X-ray diffraction (XRD) exhibited peaks characteristic of the metallic Mo phase, and the presence of silica in the amorphous and crystalline phases in the form of quartz was also verified. The results obtained in Optical Profilometry and Atomic Force Microscopy (AFM) indicate that the absorptance of the samples is influenced by the roughness of the substrates.

The CFD analysis of the effect of internal peak angle and mass-flow rates on the thermal performance of solar air heater with triangle cross-section

A new design of solar air heater with triangle cross-section is numerically studied. The thermal performance of solar air heater is studied at various mass-flow rates, inlet air temperatures, and solar irradiation intensities. The CFD model is developed using the software ANSYS FLUENT to study the fluid-flow and heat transfer in the solar air heater. The 3-D discretization is applied to study the thermal performance of solar collector with triangle cross-section. Mesh independence is performed in order to choose the adequate mesh. The discrete ordinate radiation model and the RNG k-? turbulence model are used to study the radiative heat transfer and the turbulent flow inside the solar air heater. Particularly, effects of different internal peak angles (145?,126?, 100?, 80?, and 67.5?) under different solar irradiation intensities (from 620-1081 W/m2) are studied to improve the thermal performance of the solar air heater. The results show a good agreement between the numerical model and the experimental data with an average error of 6%. The maximum outlet air temperature of the solar air heater reached 72 ?C for the geometries with 12 and 16 channels (internal peak angles of 80? and 67.5?, respectively) under mass-flow rate of 0.0264 kg/s. The thermal performances of the solar air heater with 16 and 12 channels are 24.2% higher than standard geometry, respectively for solar irradiation intensity of 1081 W/m2. The configuration with internal peak angle of 80? and 12 channels is selected as the optimal with a thermal efficiency of 79%, a low pressure drops compared to geometry with 16 channels and lower costs.

Improve the performance of solar thermal collectors by varying the concentration and nanoparticles diameter of silicon dioxide

Abstract The influence of different concentrations and nanoparticles’ diameter of silicon dioxide nanoparticles on the Nusselt number enhancement ratio and friction factor for solar thermal collector (STC) was examined numerically. The CFD model was designed to show the influence of the flow of water/SiO2 and pure water inside the pipe on the enhancement of the performance of the STC. Different concentrations of SiO2 nanoparticles are used (ϕ = 1–4%) with several nanoparticle diameters (dp = 20–50 nm). The water/SiO2 and pure water flow under different Reynolds numbers ranging from 5,000 to 30,000. The average Nusselt numbers Nuavg improved by increasing the Reynolds numbers for both fluids. The Nuavg increases with the increase in the concentration of SiO2 nanoparticles. The water/SiO2 with nanoparticle concentration of (ϕ = 5%) and nanoparticle diameter of (dp = 20 nm) has the highest Nusselt number. The Nuavg enhances 25% with water/SiO2 nanofluid flow at Re = 5,000 and 15% flow at Re = 30,000. It is noted that the skin friction factor decreases with the increase in the Reynolds number for both fluids. Water/SiO2 nanofluid has a higher skin friction factor than pure water. The Nuavg improved by 31% at the lowest Reynolds number by using water/SiO2 nanofluid as the working fluid with a change in the concentration of SiO2 nanoparticles from (ϕ = 1%) to (ϕ = 4%) and improved by 42% at the highest Reynolds number of 30,000. The decrease in the nanoparticle diameter led to an increase in the Nusselt number across all Reynolds numbers. The lowest size SiO2 nanoparticles (dp = 20 nm) provides the highest Nusselt number. The lowest size SiO2 nanoparticles (dp = 20 nm) provide the highest ratio of enhancement for the Nusselt number in STC. This investigation has confirmed that the flow of water/SiO2 with AL2O3 nanoparticles of 5% (diameter of 20 nm) has a significant influence on heat transfer enhancement to improve the thermal efficiency of STC.

The Effect of Using Secondary Reflectors on the Thermal Performance of Solar Collectors with Evacuated Tubes

The aim of this paper is to improve the thermal performance of the evacuated tube solar collectors by using secondary reflectors and covering the collector surface area with an aluminum foil. Adding a secondary reflecting surface in the form of a parabola fixed on the end of the parabolic trough, acts as an additional reflective surface, which increases the input energy to the solar collector and consequently improves the thermal output of the collector. Two solar collectors were manufactured, one with modifications and the other without modifications, which is taken as a reference for the sake of comparison. Four experiments were performed; the first and second experiments reported the influence of adding a horizontal and a vertical secondary reflector on the solar collector efficiency. In the third and fourth experiment the effect of covering the collector surface area with aluminum foil together with a secondary vertical reflector on the heat gained by the bulb is examined. It is found that the average temperature of the heat pipe bulb in case of a secondary reflector installed horizontally is about 2.5% greater than the average temperature of the reference collector, while in case of the secondary reflector installed vertically is 7% greater than the reference collector. Adding the secondary reflecting surface in the vertical position, and covering the surface area of main parabola and the secondary reflector with aluminum foil, has increased the temperature of the heat pipe bulb by 11%. Finally, adding a secondary vertical reflector to the parabolic trough collector and covering both reflectors, i.e. the primary and the secondary reflectors, with aluminum foil improve the heating capability of the solar collector.

Flat-plate solar collector thermal performance assessment via energy, exergy and irreversibility analysis

This paper presents a detail exergy analysis of a flat-plate solar collector based on irreversibility rates. The governing equations of the flat-plate collector are obtained by writing energy and exergy conservation equations for glass cover, absorber plate and working fluid. The computed results of this study are in concordance with previous studies experimental data. Our findings reveal that 84.97% of total collector irreversibility are linked to the absorber plate. Increasing the flow rate to 0.0056 kg/s decreases the irreversibility rate in the absorber plate to a minimum of 579.20 W and increases the irreversibility rate in the working fluid to it maximum of 158.83 W. The maximum exergy efficiency was 33.21% for a flow rate of 0.0056 kg/s and inlet fluid temperature of 30 °C. An increase in inlet fluid temperature from 20 to 65 °C decreases the absorber plate irreversibility by 129.13 W, meanwhile the working fluid and glass cover irreversibility increase by 30.37 W and 99.39 W, respectively. An increase in number of absorber tube from one to sixteen increases the energy and exergy efficiencies respectively by 34.61% and 92.94%. Meanwhile the absorber plate irreversibility rate increases by 97.49% and the irreversibility rates of the working fluid and glass cover reduce by 72.06% and 89.01%, respectively.

Experimental Investigation of Integrated Energy Storage on Thermal Performance Enhancement of Evacuated Glass-Thermal Absorber Tube Collector (EGATC) for Air Heating Application

Thermal energy storage (TES) in solar thermal application assist to increase the performance and efficiency of the solar thermal collector system. Various technique has been developed to enhance TES performance such as using water and PCM as energy storage material. Type of material selection and design arrangement also contribute to the performance of solar thermal collector. The aim of this research is to enhance the thermal performance of energy storage on Evacuated Glass-Thermal Absorber Tube Collector (EGATC) for air heating application. The performance study has been conducted to measure the outlet temperature and energy storage rates as per indoor setup under the artificial solar radiation on the effect of parameters such as inner absorber surface area air contact (perforated fins), outer absorber selective coating surface, outer absorber wall thickness, double layer non vacuum glass tube, single layer transparent outer glass tube and single layer thin film inner glass tube. The results showed that the performance of temperature outlet, energy store and energy buffer increase at wind speed 0.9 m/s, zero (0) perforated fin, non-coating outer absorber and 2mm outer absorber wall thickness. It was also demonstrated that a double layer vacuum glass tube showed a better thermal performance enhancement compared with double layer non-vacuum glass tube, single layer transparent outer glass tube and single layer thin film inner glass tube. This concluded that EGATC performance can be increase with those respective parameters.

Utilization of zinc-ferrite/water hybrid nanofluids on thermal performance of a flat plate solar collector-a thermal modeling approach.

Thermodynamic performance analysis is carried out on a flat plate solar thermal collector utilizing single and hybrid nanofluids. Fe2O4/water, Zn-Fe2O4/water hybrid nanofluids, and water are used as heat transfer fluids, and their performance is compared based on the energy and exergy transfer rate. The thermo-physical properties are evaluated by regression polynomial model for all the working fluids. Developed codes in MATLAB are created to solve the collector's thermal model iteratively, energy, and exergetic performance. The system is then subjected to parametric investigation and optimization for variations in fluid flow rate, temperatures, and concentrations of nanoparticles. The findings show that utilizing Zn-Fe2O4/water hybrid nanofluids with a particle concentration of 0.5% enhanced the solar collector's thermal performance by 6.6% while using Fe2O4/water nanofluids raised the collector's thermal performance by 7.83% when compared to water as the working fluid. The maximum energy efficiency of 80.1% is attained at the mass flow rate of 0.1 kg/s. The hybrid nanofluids have also given a maximum exergetic efficiency of 5.36% and an enhancement of 8.24% compared to Fe2O4/water nanofluids. It evidences that the hybrid nanofluids would become a better thermal alternative for water as well as single nanofluids.

Experimental investigation and optimization of potential parameters of discrete V down baffled solar thermal collector using hybrid Taguchi-TOPSIS method

• Hybrid Taguchi-TOPSIS optimization of discrete V down baffle in solar air channel. • CFD analysis to evaluate the difference in contribution of potential parameters. • The Nu opt and f opt for the optimum set have founded 165 and 0.061 respectively. • Secondary stream generation and mixing with primary stream stimulates turbulence. The thermo-hydraulic performance of solar thermal collector can be significantly improved by the utilization of roughness geometries in the fluid flow channel. However, the experimental investigation of turbulence promotors is a tedious and costly process. Thereby, the hybrid Taguchi-TOPSIS technique has been utilized in this work for optimization of potential parameters of discrete V down baffle in the fluid flow duct of the collector. The potential parameters of the discrete V down baffle have been selected, the relative angle of attack (α/90), relative discrete width (g w /H b ) and relative discrete position (D d /L v ). The experimental alternatives are decided by Taguchi’s L 16 orthogonal array. The optimization of potential parameters and ranking of alternatives based on the closeness index has been conducted. The optimum values of potential parameters have been found to be α/90 = 0.666, g w /H b = 1 and D d /L v = 0.67. The quantification of contribution percentage for each potential parameter on the performance of solar air heater has been conducted and found to be 33.29%, 37.25% and 29.46% for α/90, g w /H b and D d /L v respectively. The CFD analysis of solar air channel (SAC) with discrete V down baffle has been carried out for understanding the fluid flow and heat transfer mechanism, the performance of the optimum set of potential parameters and the difference in the contribution of potential parameters. This study will be beneficial for researchers and designers for optimization and understanding the effect of potential parameters on the performance of solar thermal collector utilizing air as working fluid.

Influence of artificial roughness parametric variation on thermal performance of solar thermal collector: An experimental study, response surface analysis and ANN modelling

The influence of the attack angle (αa) of the perforated baffles on thermohydraulic performance ηp of a solar thermal collector (STC) has been investigated experimentally. The experimentations have been performed to obtain the Nusselt number (Nurs) and friction factor (frs) by varying Reynolds number (Re) from 5000 to 17,000 and αa from 35° to 65°. The other geometrical parameters of angled perforated baffles are fixed in accordance with previous studies. The relative baffle height HB/HD , relative baffle pitch PB/HB , relative hole position OB/HB and open area ratio β0 are fixed at 0.50, 10, 0.266 and 12% respectively. The STC with roughened angled perforated baffles improves the Nurs and frs by 3.82 and 7.14 times respectively as compared to STC without baffles wall. The angled perforated baffles at αa of 55° provides highest thermo-hydraulic performance at Re of 9000. A thermo-hydraulic performance of 1.94 is obtained for the array of designed parameters. The statistical correlations are established for the Nurs and frs by using experimental data. The correlations obtained for the Nurs and frs predict the experimental results within a variation of ±9.7% and ±5.0% respectively. Central Composite Design (CCD) of thermo-hydraulic performance parameters is carried for the surface response analysis. Modelling of thermal parameters using CCD and Artificial Neural Network (ANN) is done which predict them with good accuracy. The previously studies on STC roughened with various types of roughness show appreciable heat transfer enhancement but very few studies have utilized angled perforated baffles. As per author knowledge, a comprehensive study on the performance analysis of STC roughened with angled perforated baffles using different techniques is not available. The study become novel because in addition to the experimental examination of STC performance, correlations for Nurs and frs from experimental data are developed and modelling of thermal parameters using CCD and Artificial Neural Network (ANN) is also performed.

Effect of Novel Phase Change Material (Pcm) Encapsulated Design on Thermal Performance of Solar Collector

Effect of Novel Phase Change Material (Pcm) Encapsulated Design on Thermal Performance of Solar Collector