scholarly journals Thermo-Hydraulic Performance Characteristics and Optimization of Protrusion Rib Roughness in Solar Air Heater

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3159
Author(s):  
Tabish Alam ◽  
Chandan Swaroop Meena ◽  
Nagesh Babu Balam ◽  
Ashok Kumar ◽  
Raffaello Cozzolino
Keyword(s):  
Temperature Increase ◽  
Hydraulic Performance ◽  
Operating Conditions ◽  
Solar Air Heater ◽  
Additional Mass ◽  
Absorber Plate ◽  
Analytical Technique ◽  
Air Heater ◽  
Flow Reynolds Number ◽  
Effective Efficiency

To enhance the thermal performance of solar air heaters (SAHs), protrusion ribs on the absorber are considered to be an attractive solution due to their several advantages. These ribs do not cause a significant pressure drop in the SAH duct and help to enhance the heat transfer to flowing air. On the other hand, a degree of roughness of the protrusion rib on the absorber can be produced by pressing the indenting device without adding additional mass. In this paper, the thermo-hydraulic performances of different roughnesses of the conical protrusion rib on the absorber plate have been evaluated by the mutual consideration of thermal as well as hydraulic performance in term of net effective efficiency. Therefore, an analytical technique has been exploited to predict the characteristics of the net effective efficiency under various operating conditions, such as the flow Reynolds number, temperature increase parameter and insolation. The effects of the conical protrusion rib roughness—namely the relative rib pitch (p/e) and relative rib height e/D) in the ranges of 6–12 and 0.200–0.044, respectively—have been evaluated. The highest value of net effective efficiency of 70.92% was achieved at a p/e of 10 and e/D of 0.0289. The optimization of the rib parameters has been carried out in different ranges of temperature increase parameters for the highest values of net effective efficiency. A unique combination of rib parameters—a p/e of 10 and e/D of 0.044—are observed to lead to the best performance when operating a solar air heater with a temperature increase parameter of more than 0.00789 K·m2/W.

scholarly journals Effect of rib roughness pitch on thermal and thermo-hydraulic performance of a solar air heater roughened artificially with arc rib having gap

2016 ◽  
Vol 8 (1) ◽  
pp. 251-256
Author(s):  
V. S. Hans ◽  
R. S. Gill ◽  
Rupinderpal Singh
Keyword(s):  
Hydraulic Performance ◽  
Solar Air Heater ◽  
Absorber Plate ◽  
Degree Relative ◽  
Number Range ◽  
Air Heater ◽  
Relative Roughness ◽  
Flow Reynolds Number ◽  
Gap Width ◽  
Rib Roughened

This experimental study on a solar air heater having absorber plate roughened artificially by providing roughness in the form of arc ribs having gap was carried out in the Department of Mechanical Engineering, Punjab Agricultural University, Ludhiana, India to study the effect of relative roughness pitch on thermal and thermohydraulic performance as well as to compare the performance of arc rib with gap roughened solar air heater with that of continuous arc rib roughened solar air heater. The roughness geometry parameters included relative roughness height of 0.043, angle of attack of 30 degree, relative gap position of 0.80, gap-width equal to the width of the rib and five values of relative roughness pitch ranging from 4 to 12 for flow Reynolds number range of 2000 to 16,000. The Nusselt number and friction factor were found to be more for relative roughness pitch value of 10 as compared to other values of relative roughness pitch. Thermo-hydraulic performance of solar air heaters roughened by arc with gap and continuous arc roughness geometries were found to be 1.91 times and 1.78 times respectively as compared to that of solar air heater having smooth absorber plate due to generation of turbulence in laminar sublayer region. However, improvement in thermo-hydraulic performance of solar air heater roughened by arc with gap geometry over continuous arc rib roughened solar air heater was attributed to generation of a region of turbulence on downstream side of the gap.

Thermal–hydraulic analysis of a solar air heater fitted with a wire-roughened absorber plate

2021 ◽  
pp. 095440892110590
Author(s):  
Nanjundappa Madhukeshwara ◽  
A Alhadhrami ◽  
Hassan A H Alzahrani ◽  
B H Prasanna
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Efficiency Index ◽  
Hydraulic Performance ◽  
Index Formula ◽  
Solar Air Heater ◽  
Absorber Plate ◽  
Air Heater ◽  
Relative Roughness ◽  
Nusselt Numbers

This study is to evaluate heat transmission and friction in a rectangular solar air heater with a V-shaped wire rib roughness on the absorber plate that operates in fully formed turbulent flow. Additionally, studies are performed to generate prediction equations for the average friction factor, Stanton number, and efficiency index. The Reynolds number [Formula: see text]–[Formula: see text], angle of attack [Formula: see text]20[Formula: see text]–90[Formula: see text]), relative roughness pitch [Formula: see text]–[Formula: see text], relative roughness height [Formula: see text]–[Formula: see text], and the aspect ratio [Formula: see text]–[Formula: see text] was varied. The efficiency index [Formula: see text] is commonly employed as a thermo-hydraulic performance metric. It is computed as [Formula: see text]. The wire roughness and airflow parameters [Formula: see text] are optimized to maximize heat transfer while retaining minimal friction losses. On the basis of resemblance criteria, average Stanton numbers, average Nusselt numbers, and even average friction factors are derived. The results are compared to those obtained with a smooth absorber duct under similar airflow circumstances in order to assess the increase in heat transfer coefficient and friction factor. The [Formula: see text], and [Formula: see text] have a significant influence on thermo–hydraulic performance, according to these studies. With [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text], the optimal configuration geometry for wire roughness and solar air heater duct is identified.

Thermo-hydraulic performance of a solar air heater with staggered C-shape finned absorber plate

2021 ◽  
Vol 168 ◽  
pp. 107068
Author(s):  
A. Saravanan ◽  
M. Murugan ◽  
M. Sreenivasa Reddy ◽  
P.S. Ranjit ◽  
P.V. Elumalai ◽  
...  
Keyword(s):  
Hydraulic Performance ◽  
Solar Air Heater ◽  
Absorber Plate ◽  
Air Heater

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.  

Three-Dimensional Thermo-Hydraulic Analysis of Solar Air Heater With Equilateral Prism-Shaped Rib Roughness

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Inzamam Ahmad ◽  
N. H. Khan ◽  
M. A. Hassan ◽  
M. K. Paswan
Keyword(s):  
Nusselt Number ◽  
Friction Factor ◽  
Average Nusselt Number ◽  
Three Dimensional ◽  
Hydraulic Performance ◽  
Solar Air Heater ◽  
Absorber Plate ◽  
Flow Friction ◽  
Air Heater ◽  
Relative Roughness

Abstract Thermal transport and flow friction characteristics due to roughness on the absorber plate of solar air heater are evaluated by applying three-dimensional finite volume based code. Renormalization group (RNG) k–ɛ model is employed to capture the turbulent nature of the flow. The effect of equilateral prism-shaped rib roughness geometrical parameters in terms of relative roughness height (e/D) and relative roughness pitch (p/e) on heat transfer and flow friction is analyzed. Further, the effect of flow parameter, Re in the range of 4000–18,000 is also explored. Results are elucidated in terms of average Nusselt number, friction factor, turbulent kinetic energy, and eddy dissipation. Results are compared with a smooth absorber plate solar air heater. Thermo-hydraulic performance of the roughened solar air heater is analyzed. Noteworthy augmentation in heat transport is obtained. The thermal enhancement factor is calculated for optimal performance and found to vary from 1.7 to 3.5. However, friction factor and pressure loss for roughened plate is significantly higher than its smooth counterpart. The pressure drop across the test section increases with the rise in roughness height due to flow obstruction. A minimum value of the friction factor enhancement ratio worth 2.13 is obtained. Enhancement in thermal transport and pressure losses are combined by introducing a thermo-hydraulic performance factor (THHP). For the range of parameters investigated, the optimum value of the thermo-hydraulic performance factor is found to be 3.41. Correlations for average Nusselt number and friction factor are offered at the end.

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