scholarly journals CFD Analysis and Taguchi-Based Optimization of the Thermohydraulic Performance of a Solar Air Heater Duct Baffled on a Back Plate

2021 ◽  
Vol 11 (10) ◽  
pp. 4645
Author(s):  
Pham Ba Thao ◽  
Duong Cong Truyen ◽  
Nguyen Minh Phu
Keyword(s):  
Nusselt Number ◽  
Taguchi Method ◽  
Solar Air Heater ◽  
Cfd Analysis ◽  
Optimal Geometry ◽  
Impingement Heat Transfer ◽  
Back Plate ◽  
Spacing Ratio ◽  
Solar Air Collector ◽  
Four Levels

In this paper, a solar air collector duct equipped with baffles on a back plate was numerically investigated. The Reynolds number (Re) was varied from 5000 to 20,000, the angle baffle (a) from 30° to 120°, the baffle spacing ratio (Pr) from 2 to 8, and the baffle blockage ratio (Br) from 0.375 to 0.75 to examine their effects on the Nusselt number (Nu), the friction factor (f), and the thermohydraulic performance parameter (η). The 2D numerical simulation used the standard k-ε turbulence model with enhanced wall treatment. The Taguchi method was used to design the experiment, generating an orthogonal array consisting of four factors each at four levels. The optimization results from the Taguchi method and CFD analysis showed that the optimal geometry of a = 90°, Pr = 6, and Br = 0.375 achieved the maximum η. The influence of Br on all investigated parameters was considerable because as Br increased, a larger primary vortex region was formed downstream of the baffle. At Re = 5000 and the optimal geometry parameters, a maximum η of 1.01 was reached. A baffle angle between 60° and 90° achieved a high Nusselt number due to the impingement heat transfer.

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.

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 Buoyancy Effect on the Flow Pattern and the Thermal Performance of an Array of Circular Cylinders

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Francesco Fornarelli ◽  
Antonio Lippolis ◽  
Paolo Oresta
Keyword(s):  
Nusselt Number ◽  
Flow Pattern ◽  
Richardson Number ◽  
Near Field ◽  
Circular Cylinders ◽  
Momentum Exchange ◽  
Force Coefficients ◽  
The Earth ◽  
Spacing Ratio ◽  
Oscillatory Character

In this paper, we found, by means of numerical simulations, a transition in the oscillatory character of the flow field for a particular combination of buoyancy and spacing in an array of six circular cylinders at a Reynolds number of 100 and Prandtl number of 0.7. The cylinders are isothermal and they are aligned with the earth acceleration (g). According to the array orientation, an aiding or an opposing buoyancy is considered. The effect of natural convection with respect to the forced convection is modulated with the Richardson number, Ri, ranging between −1 and 1. Two values of center-to-center spacing (s = 3.6d–4d) are considered. The effects of buoyancy and spacing on the flow pattern in the near and far field are described. Several transitions in the flow patterns are found, and a parametric analysis of the dependence of the force coefficients and Nusselt number with respect to the Richardson number is reported. For Ri=−1, the change of spacing ratio from 3.6 to 4 induces a transition in the standard deviation of the force coefficients and heat flux. In fact, the transition occurs due to rearrangement of the near-field flow in a more ordered wake pattern. Therefore, attention is focused on the influence of geometrical and buoyancy parameters on the heat and momentum exchange and their fluctuations. The available heat exchange models for cylinders array provide a not accurate prediction of the Nusselt number in the cases here studied.

Experimental and numerical study of an overlay composite absorber plate material for a solar air heater

2021 ◽  
Vol 63 (7) ◽  
pp. 681-686
Author(s):  
Duraisamy Jagadeesh ◽  
Ramasamy Venkatachalam ◽  
Gurusamy Nallakumarasamy
Keyword(s):  
Numerical Study ◽  
The Other ◽  
Solar Air Heater ◽  
Outlet Temperature ◽  
Cfd Analysis ◽  
Plate Material ◽  
Absorber Plate ◽  
Air Heater ◽  
Margin Of Error ◽  
Computational Processes

Abstract The research in this paper is a sequel of an earlier work by the author in which experimental and CFD results were compared for an absorber plate made of iron with and without fins for two flow rates. The research yielded a good comparative result between the experimental and computational process for an optimized flow rate and the effect of the fins. The objective of this paper is to verify the effect of the overlay composite absorber plate material on a solar air heater through experimental and computational fluid dynamics. The experimental setup consists of an absorber plate as an overlay composite of aluminum and copper for enhanced heat transfer. Experiments and CFD analysis were done in three configurations. In configuration one, only the aluminum absorber plate with fins was considered. In configuration two, the overlay composite was considered with copper on the top and aluminum at the bottom as fins, and in configuration three, the overlay composite was considered with aluminum at the top and copper at the bottom as fins. A transient 8 hours CFD analysis was carried out using these configurations. While validating the results it was found that the overlay absorber plate Cu-Al was capable of generating a high outlet temperature Max of 88 °C and capable of generating 83 °C air for 5 hours and had good thermal efficiency when compared to the other materials in the other two configuration. It was found that experimental and computational analysis were in very close agreement, and the margin of error between the experimental and computational processes was less than 8 %.

Solar Air Heater with Finned Absorber Plate and Helical Flow Path: A CFD Analysis

2020 ◽  
Vol 56 (1) ◽  
pp. 35-41
Author(s):  
Parag Jyoti Bezbaruah ◽  
Rajat Subhra Das ◽  
Bikash Kumar Sarkar
Keyword(s):  
Helical Flow ◽  
Flow Path ◽  
Solar Air Heater ◽  
Cfd Analysis ◽  
Absorber Plate ◽  
Air Heater

Study of a Cooling Feed Pipe With a Covering Plate on a Ribbed Turbine Case

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Fangyuan Liu ◽  
Junkui Mao ◽  
Chao Han ◽  
Yuanjian Liu ◽  
Xingsi Han ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Experimental Tests ◽  
Impinging Jet ◽  
Nusselt Numbers ◽  
Spacing Ratio ◽  
Wall Flow ◽  
Complicated Geometry ◽  
Clearance Control

Considering the complicated geometry in an active clearance control (ACC) system, the design of an improved cooling feed pipe with a covering plate for a high pressure ribbed turbine case was investigated. Numerical calculations were analyzed to obtain the interactions between the impinging jet arrays fed by the pipe. Experimental tests were performed to explore the effect of the Reynolds number (2000–20,000) and the jet-to-surface spacing ratio (6–10) on the streamwise-averaged Nusselt numbers. Additionally, the effect of the crossflow produced by the configuration was investigated. Results showed a confined curved channel was formed by the pipe and ribbed case, which resulted in crossflow. The crossflow evolved into vortices and the streamwise-averaged Nusselt number on the high ribs was subsequently increased. Furthermore, the distribution of the heat transfer on the entire surface became more uniform compared with that of traditional impinging jet arrays. A higher Nusselt number was achieved by decreasing the jet-to-surface spacing and increasing the Reynolds number. This investigation has revealed a cooling configuration for controlling the wall flow and evening the heat transfer on the case surface, especially for the ribs.

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