scholarly journals CFD Analysis to Study Effect of Circular Vortex Generator Placed in Inlet Section to Investigate Heat Transfer Aspects of Solar Air Heater

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Vipin B. Gawande ◽  
A. S. Dhoble ◽  
D. B. Zodpe
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Friction Factor ◽  
Vortex Generator ◽  
Inlet Section ◽  
Solar Air Heater ◽  
Cfd Analysis ◽  
Absorber Plate ◽  
Air Heater ◽  
Relative Roughness

CFD analysis of 2-dimensional artificially roughened solar air heater duct with additional circular vortex generator, inserted in inlet section is carried out. Circular transverse ribs on the absorber plate are placed as usual. The analysis is done to investigate the effect of inserting additional vortex generator on the heat transfer and flow friction characteristics inside the solar air heater duct. This investigation covers relative roughness pitch in the range of 10 ≤P/e≤ 25 and relevant Reynolds numbers in the range of 3800 ≤ Re ≤ 18000. Relative roughness height (e/D) is kept constant as 0.03 for analysis. The turbulence created due to additional circular vortex generator increases the heat transfer rate and at the same time there is also increase in friction factor values. For combined arrangement of ribs and vortex generator, maximum Nusselt number is found to be 2.05 times that of the smooth duct. The enhancement in Nusselt number with ribs and additional vortex generator is found to be 1.06 times that of duct using ribs alone. The maximum increase in friction factor with ribs and circular vortex generator is found to be 2.91 times that of the smooth duct. Friction factor in a combined arrangement is 1.114 times that in a duct with ribs alone on the absorber plate. The augmentation in Thermal Enhancement Factor (TEF) with vortex generator in inlet section is found to be 1.06 times more than with circular ribs alone on the absorber plate.

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.

Heat Transfer Augmentation Using an Innovative Helicoidal Finned Absorber Plate in a Solar Air Heater—A Numerical Study

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Shantanu Purohit ◽  
N. Madhwesh ◽  
K. Vasudeva Karanth ◽  
N. Yagnesh Sharma
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Friction Factor ◽  
Diameter Ratio ◽  
Wire Diameter ◽  
Solar Air Heater ◽  
Absorber Plate ◽  
Air Heater ◽  
Pitch Ratio

This study presents an innovative idea to augment heat transfer to an air heater using helicoidal finned arrangement. A parametric analysis of the helicoidal shaped fin geometry is considered with helicoidal pitch ratio of 0.1666–0.3, fin diameter ratio of 1.75–2. For the placement of the fin beneath the absorber plate, longitudinal pitch ratio ranging from 0.0416 to 0.1666 are used. The flow Reynolds number used for the study ranges from 4800 to 25,000. The effects of helicoidal pitch ratio, wire diameter ratio and longitudinal pitch ratio on Nusselt number and friction factor have been discussed. It is seen from the analysis that there is a significant improvement in Nusselt number for the case of helicoidal fin of wire diameter ratio of 1 when compared to base model as well as straight fin model for the operating range of Reynolds number. It is also observed from the analysis that for the helicoidal fin configuration of helicoidal pitch ratio of 0.2333, friction factor appears to be moderate. Flow and roughness parameters for roughened solar air heater have been optimized using thermal-hydraulic enhancement factor (THEF). The study reveals that by the use of helicoidal fins, maximum enhancement in the Nusselt number is found to be 2.21 times when compared to the base model for longitudinal pitch ratio of 0.0416, helicoidal pitch ratio of 0.166 for a fixed wire diameter. The improvement obtained in performance corresponding to increased Nusselt number establishes the efficacy the helicoidal fin design for the absorber plate.

Experimental Investigation of Thermohydraulic Performance of the Solar Air Heater Having Arc-Shaped Ribs With Multiple Gaps

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Sheetal Kumar Jain ◽  
Ghanshyam Das Agrawal ◽  
Rohit Misra
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Nusselt Number ◽  
Friction Factor ◽  
Solar Air Heater ◽  
Artificial Roughness ◽  
Absorber Plate ◽  
Maximum Enhancement ◽  
Air Heater ◽  
Absorber Surface

Abstract In the present research, the thermohydraulic performance of a solar air heater having artificial roughness in the form of arc-shaped ribs with multiple gaps has been investigated experimentally and compared with that of a solar air heater having smooth absorber plate. The performance has been investigated in terms of enhancement in the Nusselt number and friction factor. Results of the present work have also been compared with previously published work. Reynolds number and arc angle (α) were varied from 3000 to 18,000 and 30 deg to 75 deg, respectively. Present roughness results in a higher rate of heat transfer from the absorber surface to air, but it also imposes a penalty in terms of the increased friction factor. Maximum enhancement in Nusselt number, friction factor, and thermohydraulic performance parameter for the roughened absorber surface is found to be 3.74, 2.69, and 2.75 times that of the smooth plate, respectively. Correlations of heat transfer and friction factor for proposed roughness have also been developed.

scholarly journals Computational fluid dynamics analysis of a V-rib with gap roughened solar air heater

2018 ◽  
Vol 22 (2) ◽  
pp. 963-972 ◽  
Author(s):  
Jitesh Rana ◽  
Anshuman Silori ◽  
Rajesh Maithani ◽  
Sunil Chamoli
Keyword(s):  
Reynolds Number ◽  
Nusselt Number ◽  
Friction Factor ◽  
Angle Of Attack ◽  
Solar Air Heater ◽  
Computational Domain ◽  
Cfd Analysis ◽  
Air Heater ◽  
Relative Roughness ◽  
Computational Fluid Dynamics Analysis

A CFD analysis of a solar air heater has been carried out using V-shaped ribs as artificial roughness on the absorber plate. The relative roughness pitch, P/e = 6-12, Reynolds number of 3800-18000, relative roughness height, e/D = = 0.042, and angle of attack, ? = 30?-75?, have been selected as design variables of V-shaped rib for analysis. The ANSYS FLUENT 15.0 with renormalization group k-? turbulence model is selected for the analysis of computational domain of solar air heater. The enhancement of Nusselt number and friction factor with Reynolds number for different values of a relative roughness pitch are presented and discussed by CFD analysis. The effect of angle of attack and Reynolds number on enhancement of Nusselt number and friction factor is also presented. The optimum value of rib configuration based on constant pumping power requirement has been derived using thermohydraulic performance parameter and has been found maximum at angle of attack of 60? and P/e = 10.

scholarly journals EFFECT OF ARTIFICIAL ROUGHNESS ON HEAT TRANSFER AND FRICTION CHARACTERSTICS OF DOUBLE PASS SOLAR AIR HEATER

2013 ◽  
pp. 52-56
Author(s):  
AVDHESH SHARMA ◽  
VARUN VARUN ◽  
GAURAV BHARADWAJ
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Friction Factor ◽  
Solar Air Heater ◽  
Rectangular Duct ◽  
Artificial Roughness ◽  
Absorber Plate ◽  
Double Pass ◽  
Air Heater ◽  
Aluminium Wire

Double pass solar air heater (DPSAH) consisted of rectangular duct provided with artificial roughness on both side of the absorber plate has been experimentally investigated. Circular ribs of aluminium wire is used to provide roughness to increase heat transfer coefficient between absorber plate and air. Ribs are attached to absorber plate at four different angle of attackbetween 30° to 75° . Experiment is carried out over the range of Reynolds Number from 4900 to 12000, and relative roughness height (e/Dh) varies from 0.022 to 0.044. Experimentally different values of Nusselt number(Nu). and friction factor(fr) have been determined for various parameters. The enhance-ment in heat transfer and increment in the friction factor values of Nusselt number and friction factor have also been compared with the smooth one.

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.

scholarly journals NUMERICAL ANALYSIS FOR NUSSELT NUMBER AND HEAT TRANSFER AUGMENTATION ON SOLAR AIR HEATER ROUGHENED WITH SQUARE RIB ROUGHNESS ON THE ABSORBER PLATE

2019 ◽  
Vol 13 (1) ◽  
Author(s):  
Amit Kumar ◽  
Apurba Layek
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Numerical Study ◽  
Energy Gain ◽  
Solar Air Heater ◽  
Absorber Plate ◽  
Gain Ratio ◽  
Air Heater ◽  
Heat Transfer Augmentation ◽  
Relative Roughness

Heat transfer rate on solar air heater system is generally achieved by suitable modification of absorber plate surface with acceptable geometry of rib roughness. In this paper a numerical study is performed using CFD based computational analysis of heat transfer augmentation equipped with the square rib roughness created artificially on the absorber plate. The 2D analysis is performed using ANSYS 16.2 Code with RNG k-ε turbulence model to investigate the heat transfer and fluid flow characteristics. The augmentation of heat transfer on increase of Reynolds number enhance the Nusselt number which is referred as energy gain ratio with the use of rib roughness was examined and their relative evaluation has been plotted. The parameter which is considered for the range of analysis is taken as relative roughness pitch (P/e), relative roughness height (e/D) and the Reynolds numbers (Re) ranging from 3800-18000. The enhancement of heat transfers due to rib roughness on the absorber plate have been compared with those for smooth ducts for the same flow and thermal boundary condition to determine the energy gain ratio of solar air heater. The result obtained by the present investigation shows that the maximum value of energy gain ratio is found to be about 1.93 times the smooth duct for the studied range of parameters.

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