scholarly journals The effect of using ribbed absorber plates on enhancing the heat transfer of solar chimneys

2021 ◽  
Vol 23 (07) ◽  
pp. 1431-1444
Author(s):  
Mohammed N. Jihad ◽  
◽  
Nabil J. Yasin ◽  
Kadhum A. Jehhef ◽  
◽  
...  
Keyword(s):  
Inclination Angle ◽  
Air Gap ◽  
Test Model ◽  
Solar Chimney ◽  
Absorber Plate ◽  
Ansys Fluent ◽  
Solar Radiation Intensity ◽  
Test Models ◽  
Inclination Angles ◽  
Gap Width

Under different geometrical features and in Iraqi environmental circumstances, a numerical and experimental investigation of a solar chimney was carried out the study that dealt with an important aspect, which is to increase the surface area of the absorbent plate while maintaining the outer dimensions and limits by using three model of absorber surface (flat plate, Triangular Vgrooved corrugated plate and trapezoidal corrugated absorber plate). the work was carried out using a single vertical solar chimney of a single room has a volume 27m3 modeling 1m3 placed on the southern wall of wooden chamber having a size of (1 × 1 ×1) m and absorber plate (0.9×0.99) m. In addition to studying the effect of the air gap width (0.1, 0.2) m on the test model with all absorber plate are used at different inclination angles inward (0°,5°,10° and 15°) the test model. All variable was taken with varying solar radiation intensity (150,250,350,450,550 and 700) W/m2 along the day time. Numerical simulation of the test models using the Ansys Fluent program V18.1 to solve the governing continuity, momentum and energy equations with a standard (k-ε)standard turbulence model associated with laws of the wall along solid boundaries were solved numerically, Experimental and Theoretical results of the present study show that the optimum model of the test absorber plates with air gap width and inclination angle according to Air change per hour (ACH) calculation is Triangular V-grooved absorber plate with air gap width 0.2m and inclination angle 10°. For this inclination angle and air gap width at I700 W/m2 the ACH is about 10 % higher than model1 (flat absorber plate) and more than model3(trapezoidal plate) by 17%.

Comparative Energetic and Exergetic Analysis of Conventional and Sloped Solar Chimney Power Plants

2020 ◽  
Vol 9 (4) ◽  
pp. 57-73
Author(s):  
Hela Atia ◽  
Adrian Ilinca ◽  
Ali Snoussi ◽  
Rachid Boukchina ◽  
Ammar Ben Brahim
Keyword(s):  
Inclination Angle ◽  
Power Plants ◽  
Energetic Efficiency ◽  
Cfd Analysis ◽  
Exergy Destruction ◽  
Solar Chimney ◽  
Ansys Fluent ◽  
Solar Radiation Intensity ◽  
Fluent Software ◽  
Exergetic Analysis

A CFD analysis using ANSYS Fluent software was conducted to study the effects of collector slope on solar chimney's performances. Three solar chimney configurations, named A, B, and C, which correspond, respectively, to an inclination angle of the collector roof of 0°, 2.5°, and 5°, were investigated. The results show that the thermodynamic performances of the solar chimney were improved by increasing the inclination angle of the collector roof. In fact, the power extracted from the sloped solar chimney power plants increases with increasing the inclination angle and the solar radiation intensity, while it achieves a maximum at 800 W/m2 for configuration A. The energetic and the exergetic analysis show that configure B has the best performance in terms of conventional, effective, and total efficiencies of the collector and in terms of exergy destruction ratios in both the collector and the transition section. Whereas, configuration C has the highest amount of power extracted and the best overall energetic efficiency.

scholarly journals Prediction of Indoor Air Circulation of Residential Room with Adaptation of Solar Chimney Using Numerical Technique

2019 ◽  
Vol 8 (11) ◽  
pp. 4110-4116
Keyword(s):  
Air Temperature ◽  
Cooling System ◽  
Residential Buildings ◽  
Numerical Technique ◽  
Electrical Power ◽  
Air Gap ◽  
Solar Chimney ◽  
Heating And Cooling ◽  
Gap Width ◽  
Ventilation Velocity

With the exponential increase in consumption of electrical power during the summer season by household, there is a great need for households to withhold sustainability. To maintain the temperature of the household a passive heating and cooling system is used i.e. Solar Chimney. Ventilation, through a natural convection process, is gaining a lot of attention to be an alternative technique for mechanical air conditioning ventilation because of its reduced power usage when compared to the external cooling devices used in residential buildings of hot regions. The present study, involve solar chimney of horizontal and vertical designs in comparison with different width and height. The following paper studies the effect of a solar chimney on the indoor thermal behavior using Numerical Technique for a prototype of a residential room. The performance on the ventilation velocity and air temperature operation inside the room with varying air gap width is studied based on multiple numerical analysis solutions. The present study deals with two different architectures of a two dimensional model and results have shown that the ventilation velocity has increased to 0.017626444 kg/s and operative air temperature has been decreased by 7.26ºC for the vertical model while the horizontal model has shown a mass flow rate of 0.018027636 kg/s and a temperature decrease of 9.15ºC. The most efficient chimney was found to be model 7 which is horizontal solar chimney 3 with an air gap width of 0.05625m and a height of 0.3175 m, when compared to the other models from model number one to six.

Effect of absorber plate surface shape and glass cover inclination angle on the performance of a passive solar still

2019 ◽  
Vol 30 (6) ◽  
pp. 3183-3198 ◽  
Author(s):  
Hamid Reza Goshayeshi ◽  
Mohammad Reza Safaei
Keyword(s):  
Inclination Angle ◽  
Water Desalination ◽  
Surface Shape ◽  
Design Parameters ◽  
Solar Still ◽  
Absorber Plate ◽  
Daily Production ◽  
Content Type ◽  
Glass Cover ◽  
Inclination Angles

Purpose Solar-driven water desalination technologies are rapidly developing with various links to other renewable sources. However, the efficiency of such systems severely depends on the design parameters. This paper presents results from an investigation on the effect of the glass cover inclination angle on the performance of two stepped solar still geometries (flat and convex) and the amount of produced distilled water. Design Methodology Approach Studied inclination angles of 25°, 27.5°, 30°, 32.5° and 35° were chosen, while other design parameters were fixed. Findings The investigation showed that the unit with the convex absorber plate had higher average water daily production rate, compared to the output of the flat absorber plate unit. The results also depicted that the inclination angle of the still has a noticeable effect on the performance of solar stills. The value of the critical angle is 32.5°, and the higher inclination angle results in less heat transfer coefficient. This value can be used for design purposes and erases the typical assumption to use lower angles to optimize the productivity of the still. Practical Implications Finally, obtained data were used to correlate the Nusselt number for the flat and convex surfaces with different inclination angles of the glass cover. Originality Value The outcome of this investigation may find applications to develop highly efficient solar stills to secure more drinkable water in warm, dry lands.

Numerical Simulation of Internal Fire Whirls in an Inclined Shaft

2013 ◽  
Vol 732-733 ◽  
pp. 254-257
Author(s):  
Yan Huo ◽  
Ye Gao ◽  
De Xiang Huang
Keyword(s):  
Flow Field ◽  
Coriolis Force ◽  
Inclination Angle ◽  
Rotational Axis ◽  
Thermal Flow ◽  
Vertical Orientation ◽  
Whirling Motion ◽  
Large Eddy ◽  
Inclination Angles ◽  
Gap Width

In order to understand the characteristics of fire whirls in the inclined shaft with corner gap, large eddy simulations (LES) of thermal flow field in a 9-meter-high inclined shaft were employed. In the inclined shaft, the conrner gap is 0.3m and 0.7m in width, and the inclination angle is 5°, 30°, 45°, 50° and 55° from the vertical orientation axes respectively. It is found that a whirling flow field could be formed under proper inclination angles and corner gap width. Rotational axis of fire whirls in the inclined shaft would have same inclination angles with the shaft. Similar to the case of fire whirls in a vertical shaft, the width of corner gap of inclined shaft also influences the whirling motion of the flame. In this paper, for the same fire and inclination angle, the 0.3-meter-wide corner gap is easier to form stable fire whirls than the 0.7-meter-wide corner gap. By comparison with buoyancy, the slightly greater Coriolis force was found above a height 3m for inclined fire whirls when the width of croner gap is 0.3m, however, the Coriolis force acts only on the lower part of the shaft when the width of croner gap is 0.7m.

scholarly journals EXPERIMENTAL STUDY OF SOLAR CHIMNEY PERFORMANCE FOR PASSIVE HEATING

2018 ◽  
Vol 18 (3) ◽  
pp. 375-388
Author(s):  
Majid H Majeed ◽  
Ibrahim S Resen
Keyword(s):  
Experimental Study ◽  
Experimental Investigation ◽  
Vertical Wall ◽  
Air Gap ◽  
Passive Heating ◽  
Front Side ◽  
Solar Chimney ◽  
Constant Height ◽  
Gap Width ◽  
Indoor And Outdoor

An experimental investigation on solar chimney used for heating under climate of Iraqis carried out. Experiments were conducted on the chimney installed on vertical wall withabsorber plate placed at the front side of the air gap. The solar chimney attached to room ofdimensions (2.5×1.29×1.07) m. The chimney is studied to measure the effect of the air gapwidth with constant height of (1.07 m). Three widths are tested, namely, 0.2 m, 0.3 m and0.4 m. The experimental results showed that the solar chimney can achieve about (13 °C)difference in temperature between indoor and outdoor as well as it gives acceptabledifference in partial cloudy days. The results also indicated that the best performance ofsolar chimney is with 0.3m air gap width.

scholarly journals Outdoor Testing of a Zig-Zag Solar Air heater with and without Artificial Roughness on Absorber Plate

2019 ◽  
Vol 25 (4) ◽  
pp. 1-17
Author(s):  
Mahmoud Maustafa Mahdi ◽  
Ameer Abed Gaddoa
Keyword(s):  
Mass Flow ◽  
Inclination Angle ◽  
Steel Wire ◽  
Geographic Location ◽  
Operating Conditions ◽  
Wire Mesh ◽  
Solar Air Heater ◽  
Absorber Plate ◽  
Air Heater ◽  
Inclination Angles

In this paper, thermal performance of a zig-zig solar air heater (ZZSAH) with and without using steel wire mesh on the absorber plate of the collector is experimentally investigated. The experimental work includes four inclination angles of the collector 20o, 30o, 45o, and 60o and four air mass flow rates of 0.03, 0.04, 0.06, and 0.08 kg/s under varieties of operating conditions of a geographic location of  Baghdad. New correlation equations of Nusselt number are obtained from experimental results for both types of collectors where the effect of varying of the inclination angle of collector taken into consideration in the experiment. The correlations show good agreement with the present experimental data. In addition, the effects of mass flow rate and temperature rise across the efficiency of collector air heater are investigated. The results reveal that the efficiency of (ZZSAH) at 45o inclination angle reaches the highest values among other degrees of inclination angles for both types of collectors under study. The results also show that the addition of wire mesh magnifies the effect of inclination angle.  

scholarly journals Effects of an Inclined Blade on the Performance of a Sirocco Fan

2019 ◽  
Vol 9 (15) ◽  
pp. 3154 ◽  
Author(s):  
Shaosong Ni ◽  
Wenbin Cao ◽  
Jun Xu ◽  
Yingdong Wang ◽  
Wei Zhang
Keyword(s):  
Inclination Angle ◽  
Internal Flow ◽  
Axial Direction ◽  
Aerodynamic Performance ◽  
Baseline Model ◽  
Ansys Fluent ◽  
Fan Performance ◽  
Centrifugal Fans ◽  
Inclination Angles ◽  
Sirocco Fan

The impeller is the primary working component of centrifugal fans, whose internal flow directly determines the performance of the whole system. This work presents a numerical investigation by using ANSYS-Fluent on the internal flow of a Sirocco fan to investigate the effects of the inclination angle of the blades on the fan performance. The orientation of the blade for the baseline model is strictly along the axial direction, while three inclination angles, i.e., 3.5°, 7.0°, and 10.5°, are chosen for the inclined blades of the modified impeller to improve the aerodynamic performance of the fan. The effects of the inclined blade are demonstrated by the variations in static pressure, efficiency, and pressure and velocity distributions at various inclination angles. The computed results reveal that there is an optimum inclination angle, which produces the best aerodynamic performance.

Reducing Roof Solar Heat Gain by Using Double-Skin Ventilated Roofs

2020 ◽  
Vol 38 (3A) ◽  
pp. 402-411
Author(s):  
Mohannad R. Ghanim ◽  
Sabah T. Ahmed
Keyword(s):  
Inclination Angle ◽  
Convection Heat Transfer ◽  
Ventilation Rate ◽  
Channel Length ◽  
Air Gap ◽  
Galvanized Steel ◽  
Heat Gain ◽  
Solar Heat ◽  
Double Skin ◽  
Solar Heat Gain

Double skin ventilated roof is one of the important passive cooling techniques to reduce solar heat gain through roofs. In this research, an experimental study was performed to investigate the thermal behaviour of a double skin roof model. The model was made of two parallel galvanized steel plates. Galvanized steel has been used in the roof construction of industrial buildings and storehouses in Iraq. The effect of inclination angle (ϴ) from the horizontal and the spacing (S) between the plates was investigated at different radiation intensities. It is found that using a double skin roof arrangement with a sufficient air gap (S) can reduce the heat gain significantly. The higher the inclination angle (ϴ) the higher the ventilation rate, the lower the heat gain through the roof. In this study, increasing the air gap from 2 cm to 4 cm reduced the heat gain significantly but when the gap was further increased to 6 cm, the reduction in the heat flux was insignificant. A dimensionless correlation was also reduced between Nusselt number () and the single parameter  where L is the channel length. This correlation can be handily utilized for designing of engineering applications dealing with high temperature difference natural convection heat transfer.

Thermal Performance Analysis of a Rectangular Longitudinal Finned Solar Air Heater With Semicircular Absorber Plate

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Satyender Singh ◽  
Prashant Dhiman
Keyword(s):  
Thermal Performance ◽  
Numerical Solutions ◽  
Solar Air Heater ◽  
Duct Flow ◽  
Balance Equations ◽  
Absorber Plate ◽  
Ansys Fluent ◽  
Air Heater ◽  
Glass Cover ◽  
Good Agreement

Thermal performance of a single-pass single-glass cover solar air heater consisting of semicircular absorber plate finned with rectangular longitudinal fins is investigated. The analysis is carried out for different hydraulic diameters, which were obtained by varying the diameter of the duct from 0.3–0.5 m. One to five numbers of fins are considered. Reynolds number ranges from 1600–4300. Analytical solutions for energy balance equations of different elements and duct flow of the solar air heater are presented; results are compared with finite-volume methodology based numerical solutions obtained from ansys fluent commercial software, and a fairly good agreement is achieved. Moreover, analysis is extended to check the effect of double-glass cover and the recycle of the exiting air. Results revealed that the use of double-glass cover and recycle operation improves the thermal performance of solar air heater.

scholarly journals Acoustic Emission Characteristics and Joint Nonlinear Mechanical Response of Rock Masses under Uniaxial Compression

Energies ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 200
Author(s):  
Zhongliang Feng ◽  
Xin Chen ◽  
Yu Fu ◽  
Shaoshuai Qing ◽  
Tongguan Xie
Keyword(s):  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Inclination Angle ◽  
Failure Modes ◽  
Strain Curve ◽  
Particle Flow Code ◽  
Rock Masses ◽  
Physical Experiments ◽  
Inclination Angles ◽  
Joint Inclination

The joint arrangement in rock masses is the critical factor controlling the stability of rock structures in underground geotechnical engineering. In this study, the influence of the joint inclination angle on the mechanical behavior of jointed rock masses under uniaxial compression was investigated. Physical model laboratory experiments were conducted on jointed specimens with a single pre-existing flaw inclined at 0°, 30°, 45°, 60°, and 90° and on intact specimens. The acoustic emission (AE) signals were monitored during the loading process, which revealed that there is a correlation between the AE characteristics and the failure modes of the jointed specimens with different inclination angles. In addition, particle flow code (PFC) modeling was carried out to reproduce the phenomena observed in the physical experiments. According to the numerical results, the AE phenomenon was basically the same as that observed in the physical experiments. The response of the pre-existing joint mainly involved three stages: (I) the closing of the joint; (II) the strength mobilization of the joint; and (III) the reopening of the joint. Moreover, the response of the pre-existing joint was closely related to the joint’s inclination. As the joint inclination angle increased, the strength mobilization stage of the joint gradually shifted from the pre-peak stage of the stress–strain curve to the post-peak stage. In addition, the instantaneous drop in the average joint system aperture (aave) in the specimens with medium and high inclination angles corresponded to a rapid increase in the form of the pulse of the AE activity during the strength mobilization stage.

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