Collector Height Research Articles

The impact of turbulence models and design parameters on solar chimney power plant efficiency: A CFD study

This study numerically examines the effects of chimney height, chimney radius and collector height on the velocity, pressure and temperature distribution in a Solar Chimney Power Plant (SCPP). The analyses were performed using ANSYS Fluent software with two different turbulence models (RNG k-ε and SST k-ω). The results show that increasing the chimney height significantly boosts the outlet velocity but decreases the outlet temperature. Conversely, as the chimney radius increases, the outlet velocity decreases and the outlet temperature slightly drops. Changes in collector height result in complex behavior for both turbulence models in terms of outlet velocity and temperature, highlighting the importance of an optimal collector height. The study includes detailed and numerical data on how different turbulence models can be used for performance analysis and optimization. According to the analysis results, increasing the chimney height from 100 meters to 200 meters resulted in a 35% increase in outlet velocity and a 20% decrease in outlet temperature in the RNG k-ε model. In the SST k-ω model, the same increase raised the outlet velocity by 30% and decreased the outlet temperature by 15%. The research showed that both RNG k-ε and SST k-ω turbulence models respond notably to changes in collector height and design parameters. The RNG k-ε model reacts more quickly and sensitively, while the SST k-ω model behaves more steadily.

Numerical analysis of the divergent solar chimney power plant with a novel arc and fillet radius at the chimney base region

Solar chimney power plant (SCPP) is an ingenius concept of harnessing the solar energy for the electrical power generation, provided their efficiency is enhanced significantly. The present work focuses on the improvement of the power generation and efficiency of the plant. A finite volume CFD code is developed in FORTRAN to deal with the axisymmetric domain of the SCPP. The effect of chimney divergence angle, collector height and a novel arc and fillet radius at the chimney base is studied. For the study, an SCPP with 3 m collector diameter and 3 m chimney height with 0.05 m radius of the chimney is considered. The height of the collector is optimised and found to be 0.04 m. Diverging the chimney results in more updraft which leads to more pressure difference and increased air velocity. Also, after an optimum divergent angle, further increasing the divergence angle results in a severe reverse flow at the chimney outlet. It is observed that 2o divergent chimney is optimum which enhances air velocity by 59% and produces 290% more power than the conventional SCPP. Further improvement in the power is noticed by using the arc and fillet radii at the chimney bottom. After extensive analysis of the flow parameters, an optimum value of arc and fillet radii is proposed to be 0.1 m and 0.01 m respectively. It is noticed that for this optimum case, maximum available power is about 122% higher than the 2o divergent chimney case without any arc or fillet. The proposed design has produced an overall increment of 770% in the maximum available power of the plant and about 154% increment in the mass flow rate compared to the base case. The proposed design also enhances the collector and chimney efficiencies by about 49% and 76% respectively.

Effect of Acceptance angle on the design and performance of a heat pipe based compound parabolic collector at Kano, Nigeria

The performance of any solar collector depends on the solar radiation available, its design and orientation. The aim of this work is to develop a compound parabolic solar collector (CPC) and optimize its performance for domestic use under climatic condition of Kano, Nigeria (Φ =12.05 o N). The acceptance angle plays an important role in determining the solar radiation acceptance of the CPC collector. Therefore this paper investigates the effect of the acceptance angle on the CPC design, solar radiation collection and absorption by the heat pipe receiver installed inside the CPC collector. From the radiation data and the analysis used, this study shows that as the acceptance angle increases, the collector height decreases and the concentration ratio increases.

An application of artificial neural network (ANN) for comparative performance assessment of solar chimney (SC) plant for green energy production

This study aims to optimize the power generation of a conventional Manzanares solar chimney (SC) plant through strategic modifications to the collector inlet height, chimney diameter, and chimney divergence. Employing a finite volume-based solver for numerical analysis, we systematically scrutinize influential geometric parameters, including collector height (hi = 1.85 to 0.1 m), chimney inlet diameter (dch = 10.16 to 55.88 m), and chimney outlet diameter (do = 10.16 to 30.48 m). Our findings demonstrate that reducing the collector inlet height consistently leads to increased power output. The optimal collector inlet height of hi = 0.2 m results in a significant power increase from 51 to 117.42 kW (~ 2.3 times) without additional installation costs, accompanied by an efficiency of 0.25%. Conversely, enlarging the chimney diameter decreases the chimney base velocity and suction pressure. However, as turbine-driven power generation rises, the flow becomes stagnant beyond a chimney diameter of 45.72 m. At this point, power generation reaches 209 kW, nearly four times greater than the Manzanares plant, with an efficiency of 0.44%. Nevertheless, the cost of expanding the chimney diameter is substantial. Furthermore, the impact of chimney divergence is evident, with power generation, collector efficiency, overall efficiency, and collector inlet velocity all peaking at an outer chimney diameter of 15.24 m (corresponding to an area ratio of 2.25). At this configuration, power generation increases to 75.91 kW, approximately 1.5 times more than the initial design. Remarkably, at a low collector inlet height of 0.2 m, combining it with a chimney diameter of 4.5 times the chimney inlet diameter (4.5dch) results in an impressive power output of 635.02 kW, signifying a substantial 12.45-fold increase. To model the performance under these diverse conditions, an artificial neural network (ANN) is effectively utilized.

Dimensional investigation of solar chimney power plant based on numerical and experimental results

• Construction of prototype solar chimney and recording air flow temperature and velocity data under different solar radiation. • 3D numerical simulation of the base case using FLUENT software and validation of the results with the experimental results obtained in this study and also validation with other researcher's numerical and experimental results. • Investigation of the fluid behavior pattern inside the solar chimney and system performance based on the simulation results under different geometric parameters. In this study, a pilot solar chimney power plant (SCPP) with a chimney height of 4 m and a collector diameter of 5 m was constructed. Main purpose of this research is identification and optimization of the system based on regional climatic experimental data which recorded from constructed solar chimney with new dimensions to utilize in our future studies. So that future studies can be conducted based on a suitable platform. Performance evaluation of solar chimney was simulated under different geometric configurations through a 3D axisymmetric incompressible steady computational fluid dynamics solver by applying k - ε turbulence model. For a better performance comparison of the SCPP between different geometries, air velocity and system output power were calculated for all states. The results showed that a higher collector radius and chimney radius increased the ​​air outflow velocity in the collector, whereas a higher collector height had a negative effect. According to the results, configurations with collector height of 5 cm have the highest velocity values compared to the others and the maximum power value of 1.74 W can be achieved for the collector inlet height of 15 cm and the chimney radius of 0.4 m.

Numerical study on the effect of collector height on the performance of solar water heater collector

Numerical study on the effect of collector height on the performance of solar water heater collector

Effects of Unmanned Aerial Spray System Flight Altitude and Collector Height on Spray Deposition Measured Using a Food Dye Tracer

The use of unmanned aerial spray systems (UASS) has increased owing to their many advantages. However, studies related to a standardized method to evaluate the spray performance of UASS are lacking. Therefore, in the present study, a quantitative analytical method using a food dye tracer was compared with the image analysis method, and the effects of experimental conditions on spray deposition were assessed. Concordance between the results of quantitative and image analyses was examined. The coverage of water-sensitive paper (WSP) and Medley Velvet (MV) was compared using image analysis. Moreover, the effects of flight altitude and collector height on spray deposition amount and effective spray width were evaluated. The results showed a significant correlation between the deposition and the coverage of MV (R2 = 0.6782, p-level < 0.001). The coverage of MV is different from that of WSP. In addition, the correlation coefficient between the coverage of WSP and that of MV was smaller than the correlation coefficient between depositions and the coverage of MV. Therefore, MV should be used instead of WSP for more accurate analysis. The lower the collector height, the smaller the deposition amount. The effective spray width increased as the distance between the collector and UASS increased, whereas the total deposition amount decreased when the collector was close to the ground. Overall, using a food dye tracer, both quantitative and qualitative analyses can be applied simultaneously, and this method may replace analysis using WSP.

Thermofluid effects of solar chimney geometry on performance parameters

The solar chimney system (SCS) is a novel application that has recently become the focus of researchers in this field. The current study included a numerical simulation of changing all the variables defining the system's shape construction, in addition to the influence of curvatures on performance assessment. The approach confirms the SCS output power, velocity, and temperature based on studying more than 40 cases in various assemblages. These sets are grouped into diverse forms by changing variable parameters, including collector angle, chimney angle, collector height, turbine location, fillet radius, and shape. The findings indicated that increasing the chimney angle up to 3° increases both velocity and efficiency, while the increment in maximum velocity reaches 200% which radically improves the system power output. The change of the chimney inlet height influences the average velocity substantially from 2.04 to 2.41. The effect of collector angle efficiently improves the SCS performance for the positive angles, where the maximum increment in average velocity equals 6.25%. The greater the collector height up to 70% of turbine radius, the increase in the mass flow. The concaved shape of chimney reduces flow separation and the energy loss resulting from eddies inside it.

Experimental study of different thermal storage system effects on the performance of a small prototype solar chimney power plant

The present work is dedicated to an experimental study of a small SCPP prototype with a thermal storage system. The experimental prototype was designed, built, and set up in the laboratory of YEKARUM of Süleyman Demirel University, SDU, in Isparta, Turkey. It consists of a chimney tower of 4.2 m in height and 0.24 m in diameter and an air collector of 5.93 m in diameter with 1 m in outlet collector height. Different thermal storage systems (TES) were tested to demonstrate their effects on the performance of the prototype of the SCPP. Isparta site is suitable for installing SCPP according to its sunny property where the solar irradiation reaches 1123 W/m2. The collector's efficiency depends strongly on the thermal storage system. It is demonstrated that adding the diffuser to the experimental device increases the SCPP performance by reducing turbulence in the collector. Moreover, the crushed gravel basement is presented as the best thermal storage system, with a collector efficiency reaching 89.73%. Experimental and theoretical data have shown a good agreement. Good consistency was found between the experimental results of this study and those from the literature.

Numerical study on the effect of collector height on the performance of solar water heater collector

Numerical study on the effect of collector height on the performance of solar water heater collector

Impacts of Collector Radius and Height on Performance Parameters of Solar Chimney Power Plants: A Case Study for Manzanares, Spain

In this study, based on the Manzanares prototype, a typical SCPP system is considered with a collector height of 1.85 m, a chimney with a height of 194.6 m and a diameter of 10.16 m, and a collector with a radius of 122 m. With the 3D CFD model designed in ANSYS, the impacts of the change in the collector radius and collector height on the system performance are analysed by considering the turbulence effects. The numerical results are compared with the experimental data on the power output capacity of the pilot plant at different radiant fluxes and a good agreement is obtained. Then, by taking the chimney height and diameter constant, the numerical solutions are repeated for different collector radii in the range of 52.5-175 m. The results indicate that increasing the collector area, which means increasing the energy entering the system, leads to a notable improvement in the power output of the pilot plant. With a collector radius of 175 m, a power output of 95 kW can be obtained whereas it is 55 kW in the reference case with a collector radius of 122 m. Similarly, the solutions are repeated by changing the collector height between 1.1 and 4 m while keeping the other dimensions constant. It is seen that the increase in collector height negatively affects the performance of the system. It is observed that reducing the collector height to 1.1 m for the pilot plant can increase the power output to 61.77 kW.

Measurement and modeling of diffuse irradiance masking on tilted planes for solar engineering applications

Photovoltaic and solar thermal projects require accurate solar irradiance data and models for the design, assessment, and forecasting of power output. For panels and solar collectors installed in arrays, the view toward the sky and ground is restricted by the surrounding rows. This paper analyzes the impact of view obstructions on the diffuse irradiance distribution in fixed-tilt arrays, addressing the insufficient research coverage to date. Irradiance was measured using high-precision pyranometers placed at ten positions throughout an experimental solar collector array for 3.5 and 6 m row spacings and 30°, 37.5°, and 45° tilt angles (relative row spacings between 0.68 and 1.51). A novel anisotropic transposition model was developed to calculate the diffuse tilted irradiance along the collector height, accounting for diffuse irradiance masking due to view obstructions. The model was also solved inversely, obtaining local global horizontal irradiance from global tilted irradiance. The validation showed that the model accurately captures the distinct shape of the diffuse irradiance distribution. Results indicate a strong effect of view obstructions for narrow row spacings and steep tilt angles. For the most extreme configuration (3.5 m row spacing, 45° tilt angle, 1.67 relative row spacing), the diffuse irradiance was reduced to 64% at the bottom and 89% on average, relative to the top of the collector. As a consequence, measurements at the top can result in biased performance assessments.

Numerical Study of MXene Enhanced Therminol®VP-1 Nanofluid for Solar Photothermal Conversion

Effective and efficient utilization of solar energy is highly demanded in the energy industry. Herein, based on the excellent optical properties of MXene, an MXene enhanced therminol®VP-1 nanofluid is proposed for direct absorption solar collector to efficiently absorb solar radiation. The nanofluid is experimentally prepared and characterized. Subsequently, the influence of mass fraction of MXene, collector height, and working temperature on the collecting efficiency of the nanofluid in DASCs is numerically investigated. The results show that even with a low mass loading such as 50 ppm, MXene enhanced therminol®VP-1 nanofluid still can effectively absorbs solar spectrum. The intercept efficiency of 50ppm nanofluid is 83.32%, which is higher by 20.48% than that of therminol®VP-1. The efficiency is strongly affected by collector height and MXene content and first increases and then decreases with increasing the mass loading of MXene. Moreover, the best content of MXene gradually decreases with the increase of the collector height. These findings suggest that MXene enhanced therminol®VP-1 nanofluid has promising prospects to achieve efficient solar photothermal conversion.

Solar Chimney and Power Tower Techniques for Power Production in Nasiriya City

The solar chimney and power tower are two of modern promised energy which can develop bylow losses, simplicity and high power.In this paper, the solar chimney and fossil fuel power tower parameters are studied by usingtheoretical equations in computational fluid dynamics CFD that substituted in some computerprograms such as MATLAP and FLUENT codes with additional related expressions. Fivedifferent models are used in this paper (Chimney height is: 12, 15, 20, 25, and 35 meter),(Diameter of collector base is: 5, 8, 10, 15, and 20 meter). The effect of inlet collector height,collector absorbability, solar radiation, ambient temperature, solar collector thickness and solarcollector tilt angle are studied to find the other parameters and properties such as velocitydistribution, power and efficiency of system. The erecting of power turbine is predicted byfindings the velocity distribution between the base and chimney assembly. The numericalanalysis was presented by using GAMBIT and FLUENT 6.3 to predict that high velocity at theexpansion of chimney near the center of base – chimney bond position because of low density ofair as a result to solar radiation flux (and burned gases cover collector in case of using thechimney for combustion of gases in oil refineries).. This position is very suitable for promotingand building the power turbine. The maximum power accumulated from these techniques is morethan (6.7×105 Watt) where the velocity is (17.5 m/s). The study concluded that it is easy work toerect these chimney and power tower techniques closed to drilling and oil facilities in remoteareas. So, all factors were studied to coincide with previous papers in this field.

A computational fluid dynamics study on different solar chimney designs on solar radiation

The solar chimney power plant (SCPP) is a hopeful solution to produce electrical power from solar energy. In this paper, a 2D numerical study is presented to estimate the performance of the SCPPs while varying the collector angle, chimney diverging angle, variable solar radiation and ambient temperature and some geometrical designs. Numerical models run with solar load discrete ordinates (DO) and realizable k-ɛ turbulence models. System is defined by the collector height =50 mm, the chimney diameter =160 mm, the collector diameter =2750 mm and the chimney height =3000 mm. its investigated for each case the profile of magnitude velocity, air temperature, pressure, incident radiation and turbulence characteristics were presented. The effective choice of the best geometry is based on the maximum value of the air velocity inside the SCPP. Results indicates that a negative collector-roof positively increases the air velocity, and the output power. To a specific limit, increasing the diverging angle of the chimney has a god effect on the velocity magnitude and the other parameters. also Increasing the collector diameter and chimney height and diameter has a great effect on power output as shown in results.

Numerical assessment of transition metal nitrides nanofluids for improved performance of direct absorption solar collectors

Abstract Metallic nanostructures have attracted the attention for solar applications due to their high optical absorption cross-section, which is associated to the localized surface plasmon resonances phenomenon. In this work, the thermo-optical performance of a direct absorption solar collector using working-fluids composed of TiN, ZrN, and HfN nanospheres in an aqueous medium was evaluated using Mie theory and numerical solutions of a two-dimensional heat transfer model. The influence of nanoparticle size, volume fraction, collector height, and working-fluid temperature for the collector thermal and exergy efficiencies was investigated. Results revealed the transition metal nitrides nanoparticles have small scattering cross-sections and broad absorption peaks, matching well the solar radiation spectrum. The thermal efficiency is higher than 80% for collectors with all three nitrides nanoparticles. The collectors using TiN, ZrN, and HfN nanofluids exhibit thermal performance 50.4%, 36.5%, and 41.8%, respectively, higher than with Au nanofluid, which is a reference plasmonic material for solar applications. Moreover, collectors using transition metal nitrides reach higher outlet temperatures than with gold, leading to higher exergy efficiencies with low volume fraction. The maximum exergy efficiencies of DASC using TiN, ZrN, and HfN NF are 6.3%, 5.2%, and 5.6%, respectively, while using Au NF is 2.9%. The superior performance in a low-concentration regime allows the application of nanoparticles in the collector without increasing the required pumping work. The findings related to the photo-thermal efficiencies of transition metal nitride nanofluids, in addition to their low cost and high chemical stability, make them suitable to use for solar-related heating technologies.

On Neglecting Free-Stream Turbulence in Numerical Simulation of the Wind-Induced Bias of Snow Gauges

Numerical studies of the wind-induced bias of precipitation measurements assume that turbulence is generated by the interaction of the airflow with the gauge body, while steady and uniform free-stream conditions are imposed. However, wind is turbulent in nature due to the roughness of the site and the presence of obstacles, therefore precipitation gauges are immersed in a turbulent flow. Further to the turbulence generated by the flow-gauge interaction, we investigated the natural free-stream turbulence and its influence on precipitation measurement biases. Realistic turbulence intensity values at the gauge collector height were derived from 3D sonic anemometer measurements. Large Eddy Simulations of the turbulent flow around a chimney-shaped gauge were performed under uniform and turbulent free-stream conditions, using geometrical obstacles upstream of the gauge to provide the desired turbulence intensity. Catch ratios for dry snow particles were obtained using a Lagrangian particle tracking model, and the collection efficiency was calculated based on a suitable particle size distribution. The collection efficiency in turbulent conditions showed stronger undercatch at the investigated wind velocity and snowfall intensity below 10 mm h−1, demonstrating that adjustment curves based on the simplifying assumption of uniform free-stream conditions do not accurately portray the wind-induced bias of snow measurements.

Experimental Investigation of the Effect of Collector Profile, Tower Diameter and Tower Height on the Performance of Small-Scale Solar Updraft Power Generator

The performance of a small-scale solar updraft power generator is experimentally investigated under the effects of collector profile, tower diameter and tower height. The updraft velocity and temperature are measured from a total of 36 experiment cases. The current study’s objective is investigating the optimum configuration that produces maximum updraft velocity and mechanical power output. The highest average updraft velocity of 1.22 m/s was recorded in experiment case number A-20. The highest average mechanical power of 12.35 mW is produced by experiment case number A-24. Both the collector height and tower diameter have optimum ranges that result in maximum updraft velocity and mechanical power. Increasing the collector height is bounded by heat losses in the collector and lowering the collector height is limited by the friction force where the airflow entrance is restricted. Having a larger tower diameter could have a negative effect on system performance. This situation was observed in experiment case number A-11 where increasing the tower diameter leads to a reduction of both updraft velocity and mechanical power. Since increasing the tower height always results in increased mechanical power, the collector height must be carefully matched with the tower diameter for a given tower height.

Optimization and Minimization of Dimensions of Direct Charging Nuclear Battery Based on 90Sr Radioactive Source for Use in MEMS

Today, microelectromechanical system (MEMS) technology plays an important role in human daily life. One of the main items in MEMS design is the use of a small battery with a long life. In this work, the 90Sr radioisotope with a half-life of 28.8 years and an activity of 16.328 mCi was considered as a radioactive source. First, the 90Sr cylindrical source was designed with a gold substrate and antimony side surface coating. Then, the optimum radius and thickness of the source were investigated. Next, the optimized 90Sr cylindrical source was considered as the direct charge nuclear battery source. In the next step, the effect of collector coating on collector efficiency was investigated. Then, different positions were considered for collector placement, substrate and side surface coating and the best mode was selected. The purpose is to determine the smallest size possible for a direct charge nuclear battery with the maximum amount of short circuit current. Finally, by comparing the results of simulations performed with Monte Carlo N–Particule Transport (MCNPX) code, the present work concluded that the best parameters for direct charge nuclear battery are the use of beryllium and the 90Sr radioisotope as collector coating and source, respectively, source thickness of 0.01 µm, source radius of 37.5 µm, collector thickness 0.01 µm and collector distance from source about 3.75 µm. Under these parameters, the short circuit current is 0.092 fA. In this case, the designed direct charge nuclear battery has the highest short circuit current and the smallest dimension possible. If the dimensions of the optimized nuclear battery are 100 times, i.e., the thickness of the source increases from 0.01 to 1 µm and the radius of the source increases from 37.5 to 3750 µm, only about 2.92% of the source efficiency decreases, but the activity is 106 times more. In other words, the activity increases from 0.016328 µCi to 16.328 mCi; therefore, the short circuit current of this direct charge nuclear battery reached 0.078 nA, which is suitable for use in MEMS. Also, the collector height of this battery is 1960 µm, its radius is 3850 µm, and its thickness 1 µm.

Numerical analysis of photothermal conversion performance of MXene nanofluid in direct absorption solar collectors

A newly direct absorption solar collector (DASC) based on MXene nanofluid is proposed herein. The excellent optical properties of MXene nanofluids are experimentally determined, and a three-dimensional steady-state numerical model is developed to investigate the synergistic effect of the optical properties of MXene nanofluids and the structural parameters of the DASC. The effects of volume flow rate, working temperature, and solar concentration ratio on the photothermal conversion performance of the DASC are also analyzed. The results show that the transmittance of the MXene nanofluid evidently decreases because of the enhanced absorption of solar radiation of MXene. With the addition of MXene, the photothermal conversion efficiency of the nanofluid rapidly increases and then slightly decreases. The optimal MXene mass fraction is inversely proportional to the collector height. A mere 100 ppm of MXene nanofluid can achieve a maximum intercept efficiency of 77.49%, which is 55.47% higher than that of the base fluid. This work demonstrates the potential for the application of MXene nanofluids in the utilization of solar energy.