Simulation of Flow and Heat Transfer in Triangular Cross-Sectional Solar-Assisted Air Heater

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Rajneesh Kumar ◽  
Anoop Kumar ◽  
Varun Goel
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Roughness Parameter ◽  
Solar Air Heater ◽  
Governing Equations ◽  
Cross Sectional ◽  
Air Heater ◽  
Flow And Heat Transfer ◽  
Finite Volume Approach ◽  
D Values

The ribbed three-dimensional solar air heater (SAH) model is numerically investigated to estimate flow and heat transfer through it. The numerical analysis is based on finite volume approach, and the set of flow governing equations has been solved to determine the heat transfer and flow field through the SAH. For detailed analysis, rib chamfer height ratio (e′/e) and rib aspect ratio (e/w), two innovative parameters, have been created and considered along with the commonly used roughness parameter, i.e., relative roughness height, e/D. The parameters e′/e, e/w, and e/D are varied from 0.0 to 1, 0.1 to 1.5, and 0.18 to 0.043, respectively, but the value of P/e is kept constant for the entire investigation at 12. A good match is seen in Nusselt number (Nu) and friction factor (f) by comparing the predicted results with the experimental ones. With the variation of roughness parameters, distinguishable change in Nu and f is obtained. The highest value of thermohydraulic performance parameter (TPP) observed is 2.08 for P/e, e′/e, e/w, and e/D values of 12, 0.75, 1.5, and 0.043, respectively, at Re of 17,100. The developed generalized equation for Nu and f has shown acceptable percentage deviation under the studied range of parameters.

Heat Transfer Analysis of a Finned Solar Air Heater

1988 ◽  
Vol 110 (2) ◽  
pp. 145-155 ◽  
Author(s):  
F. Issacci ◽  
Y. Zvirin ◽  
G. Grossman
Keyword(s):  
Heat Transfer ◽  
Theoretical Method ◽  
Lower Surface ◽  
Temperature Fields ◽  
Heat Transfer Analysis ◽  
Solar Air Heater ◽  
Governing Equations ◽  
Reversed Flow ◽  
Air Heater ◽  
Transfer Processes

A theoretical method is presented for the investigation of a reflective fin solar air heater. The heat transfer processes include radiation in both the solar and IR spectra, mixed convection (forced and natural) in the air and conduction in the fins. The governing equations have been solved numerically to obtain the velocity and temperature fields in the developing and developed flow regions. The efficiency of the finned structure is then calculated, and the results of a parametric study are shown. It has been found that natural convection effects are significant and strong buoyancy leads to separation and reversed flow. The efficiency increases with lower surface emissivity and lower thermal conductivity of the fins.

NUMERICAL SIMULATION OF MIXED CONVECTION WITHIN NANOFLUID-FILLED CAVITIES WITH TWO ADJACENT MOVING WALLS

2013 ◽  
Vol 37 (4) ◽  
pp. 1073-1089 ◽  
Author(s):  
Mohammad Hemmat Esfe ◽  
Ariyan Zare Ghadi ◽  
Mohammad Javad Noroozi
Keyword(s):  
Heat Transfer ◽  
Richardson Number ◽  
Buoyancy Force ◽  
Simple Algorithm ◽  
Governing Equations ◽  
Nanofluid Flow ◽  
Flow And Heat Transfer ◽  
Case Rate ◽  
Finite Volume Approach ◽  
Opposing Effect

In this study, nanofluid flow and heat transfer in a cavity with two moving lids are investigated. Governing equations are solved by finite volume approach using SIMPLE algorithm over a staggered gird system. The results show that when the moving lids have opposing effect, the streamlines contain two main vortices. By increasing the Richardson number, intensity of the vortex complying with buoyancy force increases, while intensity of the other vortex decreases. When the moving lids have aiding effect, the streamlines contain one the primary dominant vortex in which its strength increases with increase of the buoyancy force. In this case, rate of heat transfer is more than other cases.

Fluid Flow and Heat Transfer Over a Three-Dimensional Spherical Object in a Pipe

1998 ◽  
Vol 120 (4) ◽  
pp. 985-990 ◽  
Author(s):  
N. Shahcheraghi ◽  
H. A. Dwyer
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Pipe Wall ◽  
Three Dimensional ◽  
Governing Equations ◽  
Sphere Surface ◽  
Spherical Object ◽  
Number Range ◽  
Flow And Heat Transfer ◽  
Grid Scheme

An incompressible viscous fluid flow with heat transfer over a spherical object inside a pipe is considered. The flow is made three-dimensional by an eccentric positioning of the sphere inside the pipe. The governing equations are solved by a numerical method which uses a finite volume formulation in a generalized body fitted coordinate system. An overset (Chimera) grid scheme is used to resolve the two geometries of the pipe and sphere. The results are compared to those of an external flow over a sphere, and the code is validated using such results in the intermediate Reynolds number range. The blockage effects are analyzed through evaluation of lift, drag, and heat transfer rate over the sphere. Also the change in the shear stress pattern is examined through evaluation of the local friction factor on a pipe wall and sphere surface.

Innovatively Arranged Curved-Ribbed Solar-Assisted Air Heater: Performance and Correlation Development for Heat and Flow Characteristics

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Rajneesh Kumar ◽  
Abhishek Singh Kashyap ◽  
Paramvir Singh ◽  
Varun Goel ◽  
Khushmeet Kumar
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Roughness Element ◽  
Flow Characteristics ◽  
Solar Air Heater ◽  
Quasi Steady State ◽  
Air Heater ◽  
Relative Roughness ◽  
Flow And Heat Transfer ◽  
Gap Width

Abstract Solar radiation is a rich and clean source of energy. It can be collected and converted to thermal energy with the help of flat plate collectors called the solar-assisted air heater. Because of the low coefficient of heat transfer of air, the solar-assisted air heater has low thermal performance which can be improved by creating local turbulence using surface roughness on the heat transferring plate. The present investigation has been conducted to perceive the influence of the curved-ribbed element with gap on flow and heat transfer. The roughness element is defined by using five non-dimensionlized parameters, i.e., relative roughness width (W/w), relative roughness pitch (P/e), relative gap width (g/e), relative roughness height (e/D), and relative gap distance (d/x). The radius of the curvature of the curved rib-element is kept constant and the experimental measurements were done under quasi-steady state. The thermohydraulic performance parameter improved by 3.61 times the smooth flat plate solar air heater (SAH), in curved-ribbed SAH for W/w = 3, P/e = 8, g/e = 1, e/D = 0.045, and d/x = 0.65 at Reynolds number of 23,000. The generalized relation for heat transfer and flow characteristics is also being developed and the predicted Nusselt number and friction factor with the accuracy of ± 7.5% and ± 6.7%, respectively.

Three Dimensional CFD Analysis of Solar Air Heater for Enhancement of Thermal Performance Using Arc-Shaped Wire Turbulator

2013 ◽  
Author(s):  
Vasudeva K. Karanth ◽  
Manjunath M. Shivamallaiah ◽  
Yagnesh N. Sharma
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Thermal Performance ◽  
Flow Direction ◽  
Three Dimensional ◽  
Numerical Results ◽  
Solar Air Heater ◽  
Cfd Analysis ◽  
Air Heater

A literature review carried out by the authors reveals that that a CFD analysis has not been the focus of attention to evaluate the efficacy of turbulators for improving the thermal performance of solar air heaters. A three dimensional CFD analysis is carried out in the present work to augment the performance of solar air heater. Arc shaped wire turbulators (with forward and reverse curvature aligned with flow direction), V-shaped wire turbulators (with forward and reverse geometry with respect to the flow direction) and Straight turbulators are used in this study to improve the flow turbulence and thereby enhance the convective heat transfer to air. The numerical results are validated with experimental results for model without turbulator to calibrate the numerical methodology. The numerical results show that turbulators whether curved or straight are useful in enhancing the heat transfer rates. The Arc shaped turbulators have been found to provide better heat transfer coefficient value compared to that of straight and V-shape turbulators. Also interestingly, Reverse arc turbulators seems to provide better heat transfer coefficient value compared to forward arc turbulators. Further, V-angle has no significant effect for both forward and reverse V-turbulator configurations.

scholarly journals Thermal Performance of T-shaped Obstacles in a Solar Air Heater

Processes ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1305
Author(s):  
Seung-Yong Ahn ◽  
Kwang-Yong Kim
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Friction Factor ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Channel Height ◽  
Parameter Study ◽  
Solar Air Heater ◽  
Air Heater ◽  
Performance Factor

This paper proposes T-shaped ribs as obstacles attached to the heat absorber plate in a rectangular solar air heater to promote heat transfer. The thermal and aerodynamic performance of the solar heater was numerically evaluated using three-dimensional Reynolds-averaged Navier–Stokes equations with the shear stress transport turbulence model. A parameter study was performed using the ratios of rib height to channel height, rib width to channel width, and rib width to rib height. The area-averaged Nusselt number and friction factor were selected as the performance parameters of the solar air heater to evaluate the heat transfer and friction loss, respectively. In addition, the performance factor was defined as the ratio of the area-averaged Nusselt number to the friction factor. The maximum area-averaged Nusselt number was found at h/e = 0.83 for a fixed rib area. Compared with triangular ribs, the T-shaped ribs showed up to a 65 % higher area-averaged Nusselt number and up to a 49.7% higher performance factor.

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