Experimental study of augmented heat transfer and friction in solar air heater with different orientations of W-Rib roughness

Lanjewar, Atul; Bhagoria, J.L.; Sarviya, R. M.

doi:10.1016/j.expthermflusci.2011.01.019

Cited by 127 publications

(25 citation statements)

References 19 publications

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“…This paper analyzes the efficiency of the conversion of solar energy into heat in solar air collectors. Collectors' performances depend on the collectors' materials [1,2] and the technology used in the manufacturing of the collector (form of flow channels with baffles, roughness, and induced air movement turbulence) [3][4][5][6]. Solar collectors' performance depends, also, on their operating parameters: the global solar irradiance, air-flow velocity and air-flow rate discharged through the solar collector, and operating time.…”

Section: Introductionmentioning

confidence: 99%

Solar Air Collectors for Space Heating and Ventilation Applications—Performance and Case Studies under Romanian Climatic Conditions

Budea

2014

Energies

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Solar air collectors have various applications: on the one hand, they can be used for air heating in cold seasons; on the other hand they can be used in summer to evacuate the warm and polluted air from residential, offices, industrial, and commercial buildings. The paper presents experimental results of a solar collector air, under the climatic conditions of the Southeastern Europe. The relationships between the direct solar irradiation, the resulting heat flow, the air velocity at the outlet, the air flow rate, the nominal regime of the collector and the efficiency of conversion of solar energy into thermal energy are all highlighted. Thus, it was shown that after a maximum 50 min, solar air collectors, with baffles and double air passage can reach over 50% efficiency for solar irradiation of 900-1000 W/m 2 . The article also presents a mathematical model and the results of a computational program that allows sizing solar collectors for the transfer of air, with the purpose of improving the natural ventilation of buildings. The article is completed with case studies, sizing the area to be covered with solar collectors, to ensure ventilation of a house with two floors or for an office building. In addition, the ACH (air change per hour) coefficient was calculated and compared.

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Section: Introductionmentioning

confidence: 99%

Solar Air Collectors for Space Heating and Ventilation Applications—Performance and Case Studies under Romanian Climatic Conditions

Budea

2014

Energies

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“…Langewar et al [18] W-shaped rib roughness e/D = 0.033 10 Sethi et al [19] Angular dimple-shaped elements e/D = 0.036 11 Layek et al [20] Chamfered ribs e/D = 0.040 12 Karmare and Tikekar [21] Roughness with metal grit e/D = 0.044 13 Yadav et al [32] Equilateral triangular-sectioned ribs e/D = 0.042 14 Prasad and Saini [45] Transverse wire rib roughness e/D = 0.033 15 Yadav et al [49] Square-sectioned transverse rib e/D = 0.042 16 Present numerical study Right-angle triangular ribs roughness e/D = 0.042 Thus, the heat transfer is found to be strongly dependent on the relative roughness pitch and relative roughness height of right-angle triangular rib along with the variation of Reynolds number. The average Nusselt number decreases with the increase of relative roughness pitch for a fixed value of relative roughness height.…”

Section: Heat Transfer Characteristicsmentioning

confidence: 98%

“…The enhancement in Nusselt number was reported at 60°angle of attack (a) and at relative gap position (d/w) of 0.65. Langewar et al [18] experimentally investigated the effect of W-shaped ribs arranged at an inclination with respect to the flow direction on its underside on one broad wall. For the range of parameters investigated, it was found that the highest thermo-hydraulic performance was obtained for W-down ribs as 1.98 and 1.81 for W-up ribs.…”

Section: Introductionmentioning

confidence: 99%

Experimental and CFD-based thermal performance prediction of solar air heater provided with right-angle triangular rib as artificial roughness

Gawande

Dhoble

Zodpe

et al. 2015

J Braz. Soc. Mech. Sci. Eng.

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An experimental and two-dimensional computational fluid dynamics (CFD) analysis of a solar air heater has been carried out using right-angle triangular ribs as artificial roughness on the absorber plate as a convenient method for enhancement of thermal performance of solar air heater. The relative roughness pitch (P/ e = 7.14-35.71), Reynolds number (Re = 3800-18000), and relative roughness height (e/D = 0.021-0.042) have been selected as design variables for both analysis. ANSYS FLUENT 14.5 with renormalization group k-e turbulence model is selected for the analysis of computational domain of solar air heater during CFD analysis. An enhancement in Nusselt number and friction factor with a decrease in relative roughness pitch (P/e) and increase in relative roughness height are presented and discussed with reference to experimental investigation and CFD analysis. The results of roughened solar air heater duct have been compared with smooth duct under similar flow condition. The optimum value of rib configuration based on constant pumping power requirement has been derived using thermo-hydraulic performance parameter and has been found 2.03 at P/e = 7.14. e/D = 0.042 and at a Reynolds number of 15,000 for the investigated range of parameters.

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“…This paper analyses the conversion efficiency of a solar air collector, whose performances depend on the collector's materials [1][2] and the technology used in manufacturing of the collector (form of flow channels with baffles, roughness, turbulence induced of air movement) [3][4][5][6]. The solar collector performance depends on operating parameters, the global solar irradiance, air flow velocity and air flow rate discharged through the solar collector.…”

Section: Introductionmentioning

confidence: 99%

Solar Air Colectors for Space Heating and Ventilation Applications - Performance and Case Studies in Romania Climatic Conditions

Budea

2014

Proceedings of 1st International E-Conference on Energies

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Solar air collectors have various applications: on one side, they can be used for air heating in cold seasons; on the other side they can be used in summer to evacuate the warm and polluted air from residential, offices, industrial and commercial buildings. The paper presents experimental results of a solar collector air, in climatic conditions from South Eastern Europe. The relationships between the direct solar irradiation, the heat flow resulted, the air velocity at the outlet, the air flow rate, the time of input in nominal regime of the collector and efficiency of conversion of solar energy into thermal energy are highlighted. Thus, it was shown that after maximum 50 minutes, solar air collectors, with baffles and double pass of air can reach 50 % efficiency for solar irradiation of 900-1000 W/m .2 The article also presents a mathematical model and the results of a computational program that allows sizing solar collectors for the transfer of the air, for their purpose to improve the natural ventilation of buildings. The article is completed with a case study, sizing the area to be covered with solar collectors to ensure ventilation of a house with two floors or for an office building. Also, the ACH coefficient was calculated and compared.

show abstract

Experimental study of augmented heat transfer and friction in solar air heater with different orientations of W-Rib roughness

Cited by 127 publications

References 19 publications

Solar Air Collectors for Space Heating and Ventilation Applications—Performance and Case Studies under Romanian Climatic Conditions

Solar Air Collectors for Space Heating and Ventilation Applications—Performance and Case Studies under Romanian Climatic Conditions

Experimental and CFD-based thermal performance prediction of solar air heater provided with right-angle triangular rib as artificial roughness

Solar Air Colectors for Space Heating and Ventilation Applications - Performance and Case Studies in Romania Climatic Conditions

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