Experimental and CFD-based thermal performance prediction of solar air heater provided with chamfered square rib as artificial roughness

The present work investigates the exergy and effective efficiency of the multi-pass solar air collector with longitudinal fins by analysis approach and multi-objective optimization. The effect of 0.01-0.02 kg/s air flow rate, 15-35 mm collector depth, 1-3 m collector length, and 24.21-30.67 mm fin pitch was considered. The optimization was analyzed by the Preference Selection Index (PSI) method, with three maximum criteria: thermal efficiency, effective efficiency, and exergy efficiency. Mathematical models were solved by EES software. Results indicated that the multi-pass (TPLF and DPLF) type was better than the SPWF type by three criteria. The highest exergy efficiency of the TPLF and DPLF types was 6.696% and 5.636%. The greatest effective efficiency of the TPLF and DPLF types was 69.09% and 66.17%. Furthermore, the optimization results indicated that the three efficiency criteria of the DPLF type were 58.38%, 58.22%, and 4.491% for the best case; the three efficiency criteria of the TPLF type were 60.97%, 60.85%, and 5.439% for the best case. The worst configuration was the model with a short collector length, large collector depth, and large fin pitch. The collector efficiency decreased with decreased fin pitch for the configuration with the large collector length, short collector depth, and high mass flow rate.

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“…𝑁𝑢 𝑓 = 0.018𝑅𝑒 0.8 𝑃𝑟 0.4 , for channel with longitudinal fins (15) The radiation HTC between surfaces is calculated as follows [50]…”

Section: Methodology 21 Geometry Model and Energy Balancementioning

confidence: 99%

The Effective and Exergy Efficiency of Multi-Pass Solar Air Collector with Longitudinal Fins: Analysis and Optimization

Nhut

Minh²,

Thanh³

2023

ARFMTS

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“…The friction factor for the ribbed solar air collector is calculated by, 39 f P l D ρu = (Δ / ) 2 . r h 2 (11) Pumping power can be calculated by…”

Section: Performance Parametersmentioning

confidence: 99%

“…The maximum friction factor ( f ) was found at Re = 4000, which was 3.14 occasions higher than the smooth channel. Gawande et al 11 have concentrated on SAH with chamfered square ribs on the aluminum plate. They considered for p/h = 7.14–17.86, chamfer point from 0° to 40° to a consistent relative roughness height ( h/H ) = 0.042.…”

Section: Introductionmentioning

confidence: 99%

Energy and exergy analysis of solar air heater with trapezoidal ribs based absorber: A comparative analysis

Gogada

Roy

Gupta

et al. 2022

Energy Science & Engineering

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The performance of a solar air heater (SAH) is computationally investigated in this study using COMSOL multiphysics software. The present study aims to enhance the performance of smooth SAH with the help of artificial roughness. To achieve the goal, trapezoidal ribs above (Model 1) and below (Model 2) the absorber were fixed. The thermo‐hydraulic characteristics of smooth SAH were compared with the thermo‐hydraulic performances of Model 1 and Model 2. The computations were made by varying the heat flux between 600 and 1000 W/m2, Reynolds number from 4000 to 7000, relative rib height (h/H) from 0.2 to 0.7, and a constant pitch of 15 mm. The maximum enhancement in Nusselt number (Nu) compared to smooth duct was 5.54 times for Model 1 and 5.42 times for Model 2 at a h/H = 0.7 at Re = 7000. The maximum increase in friction factor was 36.97 times more than the smooth duct. The thermal performance factor (TPF) at 1000 W/m2 ranged from 1.29 to 1.72 for Model 1 and 1.27 to 1.68 for Model 2. It is found that trapezoidal ribs of Model 1 with h/H of 0.6 has delivered a maximum TPF of 1.72 at Re = 7000. The optimized relative rib height was found to be 0.6. The maximum exergy efficiency of 10.40% was obtained for Model 1 with h/H of 0.6 and at 1000 W/m2.

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“…The conventional rib profiles such as rectangular, triangular, square, circular, and so on [7][8][9][10][11][12] were resented. The analysis of nonconventional rib profiles, for example T typed, reverse L, chamfered square, intersecting, semicircular, and so on [13][14][15][16][17][18][19][20][21] were explored.…”

Section: Introductionmentioning

confidence: 99%

Computational and experimental performance assessment of rectangular sectioned solar air heater duct provided with new curved ribs

Deshpande,

Raibhole

2024

Heat Trans

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There are many applications, such as fruits, paddy rice drying, and so on, where air heaters are comprehensively used. The provision of ribs in solar energy‐based air heaters has been accredited to be a beneficial approach for escalating its thermal performance. This investigation reveals the performance evaluation of a rectangular sectioned solar air heater duct placed with the curved type of ribs organized in noncontinuous and truncation patterns. Influence of variation of pitch ratio (4.0–12.0), block‐age ratio (0.06–0.1), the ratio of rib height to the radius of rib curvature (0.75–1), and the ratio of rib truncation gap to its height (0–0.75) at different values of Reynolds's numbers (Re) in the range 12,000–37,000 on the performance revealing factors explicitly heat transfer augmentation factor, the ratio of friction factor, as well as overall thermal performance enhancement (OTPE) have been discussed. The experimentation was performed on a similar rectangular air heater as that of numerical simulation with the same boundary conditions. It is figured out from numerical simulation that the provision of a central truncation gap in the arrangement of ribs helped in the development of vortices with minimal pressure loss due to friction. The greatest Nusselt number augmentation ratio between ribbed and plain plates that was attained is of the order of 2.01 for a pitch ratio of 9.0, blockage ratio of 0.08, the ratio of rib height to the radius of rib curvature 0.25 at the highest value of Re. The obtained friction factor ratio between the ribbed plate and the plain plate is of the order of 2.34 for p/y = 9.0 at maximum Re. The highest value of overall thermal performance enhancement (OTPE) is attained as 1.52 at the pitch ratio of 9, at the maximum value of Re. The central truncation gap of the rib pattern promoted the creation of vortices with a decreased pressure loss penalty. The uppermost value of the factor presenting overall thermal performance enhancement in this work is far superior to unity. This suggests that adding curved ribs to the air heater's duct is a helpful way to improve its overall performance. Empirical correlations have been established between the Nusselt number and geometrical parameters, likewise the friction factor and geometrical parameters using the regression study. The values of the Nusselt number, and friction factor that come from experimental work and developed empirical correlations fall between the highest deviation limits of ±9% and ±8%, respectively. This work is certainly helpful in the context of solar air heaters used for applications such as drying paddy rice.

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Experimental and CFD-based thermal performance prediction of solar air heater provided with chamfered square rib as artificial roughness

Cited by 59 publications

References 32 publications

The Effective and Exergy Efficiency of Multi-Pass Solar Air Collector with Longitudinal Fins: Analysis and Optimization

The Effective and Exergy Efficiency of Multi-Pass Solar Air Collector with Longitudinal Fins: Analysis and Optimization

Energy and exergy analysis of solar air heater with trapezoidal ribs based absorber: A comparative analysis

Computational and experimental performance assessment of rectangular sectioned solar air heater duct provided with new curved ribs

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