scholarly journals Experimental Investigation of Thermohydraulic Performance of a Rectangular Solar Air Heater Duct Equipped with V-Shaped Perforated Blocks

2014 ◽  
Vol 6 ◽  
pp. 948313 ◽  
Author(s):  
Tabish Alam ◽  
R. P. Saini ◽  
J. S. Saini
Keyword(s):  
Heated Surface ◽  
Geometrical Parameters ◽  
Solar Air Heater ◽  
Open Area ◽  
Pumping Power ◽  
Height Ratio ◽  
Air Heater ◽  
Relative Pitch ◽  
Pitch Ratio ◽  
Better Than

This paper presents the thermohydraulic performance of rectangular solar air heater duct equipped with V-shaped rectangular perforated blocks attached to the heated surface. The V-shaped perforated blocks are tested for downstream (V-down) to the air flow at Reynolds number from 2000 to 20000. The perforated blocks have relative pitch ratio ( P/e) from 4 to 12, relative blockage height ratio ( e/H) from 0.4 to 1.0, and open area ration from 5% to 25% at a fixed value of angle of attack of 60∘ in a rectangular duct having duct aspect ratio ( W/H) of 12. Thermohydraulic performance is compared at different geometrical parameters of V-shaped perforated blocks for equal pumping power which shows that maximum performance is observed at a relative pitch of 8, relative rib height of 0.8, and open area ration of 20%. It is also observed that the performance of V-shaped perforated blocks was better than transverse-perforated blocks.

Heat Transfer Enhancement due to V-Shaped Perforated Blocks in a Solar Air Heater Duct

2014 ◽  
Vol 619 ◽  
pp. 125-129 ◽  
Author(s):  
Tabish Alam ◽  
R.P. Saini ◽  
J.S. Saini
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Friction Factor ◽  
Heated Surface ◽  
Solar Air Heater ◽  
Transfer Enhancement ◽  
Experimental Conditions ◽  
Enhancement Of Heat Transfer ◽  
Relative Pitch ◽  
Pitch Ratio

An experimental study of enhancement of heat transfer due to V-shaped perforated blockages attached to the heated surface has been presented in this paper. The duct equipped with perforated V-blocks had an aspect ratio (W/H) of 12, relative blockage height ratio (e/H) of 0.8, angle of attack (α) of 60° and open area ratio (β) of 20%, while relative pitch ratio (P/e) was varied from 4 to 12. The values of Nusselt number and friction factor of the duct with blockages were compared with values of Nusselt number and friction factor of the smooth duct operating under similar experimental conditions. It was found that there was a significant effect on the Nusselt number ratio and friction factor ratio when the pitch ratio was changed and there was exist an optimum value of pitch ratio. Thermal hydraulic performance was found to be maximum corresponding to relative pitch value of 8.

scholarly journals Parametric CFD Thermal Performance Analysis of Full, Medium, Half and Short Length Dimple Solar Air Tube

2021 ◽  
Vol 13 (11) ◽  
pp. 6462
Author(s):  
Mir Waqas Alam ◽  
Basma Souayeh
Keyword(s):  
Thermal Performance ◽  
Energy Transport ◽  
Hydraulic Performance ◽  
Short Length ◽  
Working Fluid ◽  
Solar Air Heater ◽  
Hydraulic Characteristics ◽  
Height Ratio ◽  
Pitch Ratio ◽  
Full Medium

In the present decade, research regarding solar thermal air heaters (SAHs) has noticed a continuous progression in thermo-hydraulic performance augmentation approaches. There now exists a wide variety of thermo-hydraulic performance augmentation approaches and researchers have designated various structures. Nevertheless, there seems to be no generalization to any of the approaches employed. The present numerical investigation reports on the thermo-hydraulic characteristics and thermal performance for flow through a varied length (full, medium, half, and short length) dimple solar air heater (SAH) tube. The study highlights recent developments on enhanced tubes to augment heat transfer in SAH. The influence of different length ratio, dimple height ratio (H), and pitch ratio (s) on thermo-hydraulic characteristics have been investigated in the Reynolds number (Re) range from 5000 to 25,000. Air is used as the working fluid. The commercial software ANSYS Fluent is used for simulation. The shear stress transport (SST) model is used as the turbulence model. Thermal energy transport coefficient is increased in the full-length dimple tube (FLDT), compared to the medium-length dimple tube (MLDT), half-length dimple tube (HLDT) and short-length dimple tube (SLDT). Similarly, the pitch ratio (s) has more influence on Nusselt number (Nu) compared to the dimple height ratio (H). The friction factor decreases with an increase in pitch ratio. Nu increases and f decreases with increasing Re for all combinations of H and s. Low s and higher H yields high enhancement of HT and PD. Integration of artificial roughness on the tube increases the values of Nu and f by 5.12 times and 77.23 times for H = 0.07, s = 1.0 at Re value of 5000 and 25,000, respectively, in regard to the plain tube. For all the tested cases, the thermo-hydraulic performances (η) are greater than unity.

Experimental Investigation of Enhanced Heat Transfer and Pressure Drop in a Solar Air Heater Duct With Discretized Broken V-Rib Roughness

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
Anil Kumar Patil ◽  
J. S. Saini ◽  
Krishna Kumar
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Geometrical Parameters ◽  
Solar Air Heater ◽  
Enhanced Heat Transfer ◽  
Transfer Rates ◽  
Air Heater ◽  
Effective Efficiency ◽  
Flow Through ◽  
Considerable Enhancement

The present study examines the augmentation in heat transfer and friction in a flow through solar air heater duct with discretized broken V-rib roughness. The experimental outcomes pertaining to Reynolds number from 3000 to 17,000, relative gap position (s′/s) from 0.2 to 0.8, relative staggered rib position (p′/p) from 0.2 to 0.8 have been presented and discussed. Discretized broken V-rib roughness brought out considerable enhancement in heat transfer rates over V-rib roughness and smooth duct. Effective efficiency of discretized broken V-rib roughened solar air heater is estimated and geometrical parameters of roughness are optimized with regard to temperature rise parameter and insolation.

Performance Investigation of a Triangular Solar Air Heater Duct Having Broken Inclined Roughness Using Computational Fluid Dynamics

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Sheetal Kumar Jain ◽  
Ghanshyam Das Agrawal ◽  
Rohit Misra ◽  
Prateek Verma ◽  
Sanjay Rathore ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Large Scale ◽  
Rectangular Cross Section ◽  
Heated Surface ◽  
Clean Energy ◽  
Solar Air Heater ◽  
Air Heater ◽  
Gap Width

Large-scale adaptation of solar air heating in industries and agro-processing will lead to clean energy processing as well as reducing the production cost for these industries. The solar air heater uses the principle of the greenhouse effect to heat air through the collected heat in the absorber. Among the various techniques employed by the researchers to augment heat transfer, the addition of artificial roughness elements/fins/corrugations on the heated surface is the promising one for heat transfer augmentation. In the present work, the effect of broken inclined ribs with rectangular cross-section on heat transfer and friction characteristics of the equilateral triangular passage duct has been analyzed using computational fluid dynamics. The effect of roughness parameters, viz., relative gap position and relative gap width, is being investigated for the Reynolds number (Re) ranging from 4000 to 18,000. The values of relative gap position (d/W) and relative gap width (g/e) are varied from 0.16 to 0.67 and 0.5 to 2, respectively, while a constant heat flux is supplied on the absorber side, other surfaces being insulated. The Nusselt number increased up to 2.16 times by using broken ribs than that of the smooth duct at d/W = 0.25 and g/e = 1.

Thermal performance enhancement of flat plate solar air heater using transverse U-shaped turbulator - A numerical study

2019 ◽  
Vol 13 (3) ◽  
pp. 5562-5587 ◽  
Author(s):  
M. S. Manjunath ◽  
R. Venkatesh ◽  
N. Madhwesh
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Enhancement Factor ◽  
Performance Enhancement ◽  
Numerical Study ◽  
Solar Air Heater ◽  
Air Heater ◽  
Relative Pitch ◽  
Thermal Enhancement ◽  
Thermal Enhancement Factor

The aim of this study is to determine the effect of U-shaped rib turbulator on the flow and heat transfer characteristics of flat plate solar air heater using two dimensional CFD analysis. The analysis is carried out using the CFD software tool ANSYS Fluent for the flow Reynolds number ranging from 9000 to 21,000.The relative pitch(P/e) of the U-shaped rib is varied as 5, 10, 25 and 40 for a fixed relative rib height of 0.0421. It is shown that the U-shaped rib augments the Nusselt number by about 1.76 times while the friction factor increased by about 1.95 times with reference to smooth duct for a relative pitch of 10 and 5 respectively. The maximum thermal enhancement factor is obtained as 1.5 for the configuration of P/e=25. A comparative analysis of U-shaped rib with circular rib reveals that the U-shaped rib turbulator is found to be more effective in providing heat transfer enhancement and has about 15% higher thermal enhancement factor as compared to circular turbulator.

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.

scholarly journals Effects of Louvered Parameters on Exergetic Performance of Louvered Finned Solar Air Heater

2021 ◽  
Vol 39 (5) ◽  
pp. 1649-1658
Author(s):  
Subhash Chand ◽  
Prabha Chand
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Operating Conditions ◽  
High Mass ◽  
Solar Air Heater ◽  
Air Heater ◽  
Pitch Ratio ◽  
Exergy Performance

The aim of the present study to improve the performance of solar air heater because of low thermo-physical properties of air. In the current work, an attempt has been made to improve the performance of the heater by employing louvered fins to the absorber plate, as it not only enhances heat transfer coefficient but also improve heat transfer area. The effect of exergy performance on the geometrical parameters of louvered fin i.e., louvered angle, louvered pitch and louvered length has been studied and analyzed. The results are compared to plane solar air heater (PSAH) to evaluate the effectiveness of louvered finned solar air heater (LFSAH). The exergy efficiency of LFSAH is comparatively higher for all the operating conditions except for higher mass flow rate where it may even go below that of PSAH; possibly due to the higher pressure drop and more loss of exergy at high mass flow rate. In addition, the results conclude that for louvered parameters viz., louvered angle 20°, fin pitch to louvered pitch ratio 0.75 and louvered length to louvered pitch ratio 1.25, high exergy performance of SAH is obtained as compared to other louvered parameter values.

Geometrical Optimization of a Smooth Solar Air Heater Duct

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
G. K. Chhaparwal ◽  
Ram Dayal ◽  
Rahul Goyal ◽  
Ankur Srivastava
Keyword(s):  
Aspect Ratio ◽  
Geometrical Parameters ◽  
Bejan Number ◽  
Solar Air Heater ◽  
Air Velocity ◽  
Frictional Loss ◽  
Air Heater ◽  
Geometrical Optimization ◽  
Optimum Geometry ◽  
Mass Flowrate

Abstract This study presents the geometrical optimization of a solar air heater. A reasonable working range of geometrical parameters: length 1–3 m, width 0.1–0.5 m, and height 0.005–0.05 m (or aspect ratio 1–20), is investigated as per general applications and installation constraints. The effect of these geometrical parameters on thermal (heat flux and outlet air temperature) and hydraulic (air velocity, mass flowrate, pressure loss and pumping power, and Bejan number) parameters are theoretically studied. Later, a numerical investigation is carried out with an optimum geometry of SAH-duct (length 2.44 mm and width 0.3 m), for aspect ratio 4–18 and Re 3000–15,000. An experimental study is also done to validate numerical results. The heat transfer and frictional loss do not show a significant change in the values for the aspect ratio 8–12.

Influence of twisted tape fins on heat transfer and friction factor characteristics for impinging jet solar air heater

2021 ◽  
pp. 095440892199528
Author(s):  
MM Matheswaran ◽  
TV Arjunan ◽  
Mukesh K Sahu
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Impinging Jet ◽  
Operating Conditions ◽  
Design Parameters ◽  
Twisted Tape ◽  
Solar Air Heater ◽  
Air Heater ◽  
Twist Ratio ◽  
Pitch Ratio

In this work, an experimental study was carried out to investigate the enhancement of heat transfer and friction factor characteristics of an impinging jet solar air heater integrated with twisted tape fins. During the analysis, the Reynolds number fin design parameters namely twist ratio (Y), and pitch ratio (py) are varied from 3500 –13500, 5.5–9.5, and 0.1–0.3, respectively. During the experimentation, the constant heat flux of 1000 W/m2 was maintained on the absorber plate. From the results, it was observed that the heat transfer rate increases while increasing the twist ratio up to 7.5 and further increase in twist ratio diminishes the performance. It was also concluded that the rise in pitch ratio (py) deteriorates the rate of heat transfer. The present work enhances the heat transfer and friction factor by the maximum of 1.9 and 1.81 times as compared with the conventional jet impingement solar air heater at identical operating conditions.

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