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

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.

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Augmentation of Heat Transfer in a Circular Channel with Inline and Staggered Baffles

Energies ◽

10.3390/en14248593 ◽

2021 ◽

Vol 14 (24) ◽

pp. 8593

Author(s):

Muneerah Al Nuwairan ◽

Basma Souayeh

Keyword(s):

Heat Transfer ◽

Thermal Performance ◽

Working Fluid ◽

Solar Air Heater ◽

Circular Channel ◽

Maximum Enhancement ◽

Performance Factor ◽

Thermal Performance Factor ◽

Sst Model ◽

Inlet Length

This numerical investigation presents the effects of the position of baffles in the shape of a circle’s segment placed inside a circular channel to improve the thermal and flow performance of a solar air heater. Three different baffles’ positions with Reynolds number varying between 10,000 to 50,000 were investigated computationally. The k-omega SST model was used for solving the governing equations. Air was taken as the working fluid. Three pitch ratios (Y = 3, 4, and 5) were considered, while the height of the baffles remained fixed. The result showed an enhancement in Nusselt number, friction factor, j-factor, and thermal performance factor. Staggered exit-length baffles showed maximum enhancement in heat transfer and pressure drop, while inline inlet-length baffles showed the least enhancement. For a pitch ratio of Y = 3.0, the enhancement in all parameters was the highest, while for Y = 5.0, the enhancement in all parameters was the least. The highest thermal performance factor of 1.6 was found for SEL at Y = 3.0.

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Application of New Artificial Neural Network to Predict Heat Transfer and Thermal Performance of a Solar Air-Heater Tube

Sustainability ◽

10.3390/su13137477 ◽

2021 ◽

Vol 13 (13) ◽

pp. 7477

Author(s):

Suvanjan Bhattacharyya ◽

Debraj Sarkar ◽

Rahul Roy ◽

Shramona Chakraborty ◽

Varun Goel ◽

...

Keyword(s):

Neural Network ◽

Heat Transfer ◽

Machine Learning ◽

Artificial Neural Network ◽

Thermal Performance ◽

Neural Network Model ◽

Artificial Neural Network Model ◽

Solar Air Heater ◽

Pitch Ratio ◽

Artificial Neural

In the present study, the heat transfer and thermal performance of a helical corrugation with perforated circular disc solar air-heater tubes are predicted using a machine learning regression technique. This paper describes a statistical analysis of heat transfer by developing an artificial neural network-based machine learning model. The effects of variation in the corrugation angle (θ), perforation ratio (k), corrugation pitch ratio (y), perforated disc pitch ratio (s), and Reynolds number have been analyzed. An artificial neural network model is used for regression analysis to predict the heat transfer in terms of Nusselt number and thermohydraulic efficiency, and the results showed high prediction accuracies. The artificial neural network model is robust and precise, and can be used by thermal system design engineers for predicting output variables. Two different models are trained based on the features of experimental data, which provide an estimation of experimental output based on user-defined input parameters. The models are evaluated to have an accuracy of 97.00% on unknown test data. These models will help the researchers working in heat transfer enhancement-based experiments to understand and predict the output. As a result, the time and cost of the experiments will reduce.

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

Advances in Mechanical Engineering ◽

10.1155/2014/948313 ◽

2014 ◽

Vol 6 ◽

pp. 948313 ◽

Cited By ~ 7

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.

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Experimental study of thermohydraulic characteristics and irreversibility analysis of novel axial corrugated tube with spring tape inserts

The European Physical Journal Applied Physics ◽

10.1051/epjap/2020200192 ◽

2020 ◽

Vol 92 (3) ◽

pp. 30901

Author(s):

Suvanjan Bhattacharyya ◽

Debraj Sarkar ◽

Ulavathi Shettar Mahabaleshwar ◽

Manoj K. Soni ◽

M. Mohanraj

Keyword(s):

Heat Transfer ◽

Experimental Study ◽

Thermal Performance ◽

Working Fluid ◽

The Novel ◽

Heat Exchanger Tube ◽

Heat Transfer Augmentation ◽

Corrugated Tube ◽

The Impact ◽

Exchanger Tube

The current study experimentally investigates the heat transfer augmentation on the novel axial corrugated heat exchanger tube in which the spring tape is introduced. Air (Pr = 0.707) is used as a working fluid. In order to augment the thermohydraulic performance, a corrugated tube with inserts is offered. The experimental study is further extended by varying the important parameters like spring ratio (y = 1.5, 2.0, 2.5) and Reynolds number (Re = 10 000–52 000). The angular pitch between the two neighboring corrugations and the angle of the corrugation is kept constant through the experiments at β = 1200 and α = 600 respectively, while two different corrugations heights (h) are analyzed. While increasing the corrugation height and decreasing the spring ratio, the impact of the swirling effect improves the thermal performance of the system. The maximum thermal performance is obtained when the corrugation height is h = 0.2 and spring ratio y = 1.5. Eventually, correlations for predicting friction factor (f) and Nusselt number (Nu) are developed.

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INFLUENCE OF WORKING FLUID ON THERMAL PERFORMANCE OF THERMOSYPHONS FOR APPLICATION IN HIGH PRESSURE VACUUM TUBE SOLAR COLLECTORS

10.26678/abcm.encit2020.cit20-0621 ◽

2020 ◽

Author(s):

Guilherme Antonio Bartmeyer ◽

Victor Vaurek Dimbarre ◽

Pedro Leineker Ochoski Machado ◽

PAULO HENRIQUE DIAS DOS SANTOS ◽

Thiago Antonini Alves

Keyword(s):

High Pressure ◽

Thermal Performance ◽

Working Fluid ◽

Solar Collectors ◽

Vacuum Tube

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Thermal Performance Analysis of a Rectangular Longitudinal Finned Solar Air Heater With Semicircular Absorber Plate

Journal of Solar Energy Engineering ◽

10.1115/1.4032010 ◽

2015 ◽

Vol 138 (1) ◽

Cited By ~ 7

Author(s):

Satyender Singh ◽

Prashant Dhiman

Keyword(s):

Thermal Performance ◽

Numerical Solutions ◽

Solar Air Heater ◽

Duct Flow ◽

Balance Equations ◽

Absorber Plate ◽

Ansys Fluent ◽

Air Heater ◽

Glass Cover ◽

Good Agreement

Thermal performance of a single-pass single-glass cover solar air heater consisting of semicircular absorber plate finned with rectangular longitudinal fins is investigated. The analysis is carried out for different hydraulic diameters, which were obtained by varying the diameter of the duct from 0.3–0.5 m. One to five numbers of fins are considered. Reynolds number ranges from 1600–4300. Analytical solutions for energy balance equations of different elements and duct flow of the solar air heater are presented; results are compared with finite-volume methodology based numerical solutions obtained from ansys fluent commercial software, and a fairly good agreement is achieved. Moreover, analysis is extended to check the effect of double-glass cover and the recycle of the exiting air. Results revealed that the use of double-glass cover and recycle operation improves the thermal performance of solar air heater.

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