Experimental investigation on heat transfer and friction factor for an inclined spherical ball roughened solar air heater

2018 ◽  
Vol 18 (1) ◽  
pp. 7-36
Author(s):  
Ramesh MURMU ◽  
P KUMAR ◽  
HN SINGH
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Friction Factor ◽  
Solar Air Heater ◽  
Air Heater ◽  
Spherical Ball

Experimental Investigation of Thermohydraulic Performance of the Solar Air Heater Having Arc-Shaped Ribs With Multiple Gaps

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Sheetal Kumar Jain ◽  
Ghanshyam Das Agrawal ◽  
Rohit Misra
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Nusselt Number ◽  
Friction Factor ◽  
Solar Air Heater ◽  
Artificial Roughness ◽  
Absorber Plate ◽  
Maximum Enhancement ◽  
Air Heater ◽  
Absorber Surface

Abstract In the present research, the thermohydraulic performance of a solar air heater having artificial roughness in the form of arc-shaped ribs with multiple gaps has been investigated experimentally and compared with that of a solar air heater having smooth absorber plate. The performance has been investigated in terms of enhancement in the Nusselt number and friction factor. Results of the present work have also been compared with previously published work. Reynolds number and arc angle (α) were varied from 3000 to 18,000 and 30 deg to 75 deg, respectively. Present roughness results in a higher rate of heat transfer from the absorber surface to air, but it also imposes a penalty in terms of the increased friction factor. Maximum enhancement in Nusselt number, friction factor, and thermohydraulic performance parameter for the roughened absorber surface is found to be 3.74, 2.69, and 2.75 times that of the smooth plate, respectively. Correlations of heat transfer and friction factor for proposed roughness have also been developed.

Experimental Investigation of Heat Transfer and Friction Characteristics of Arc-Shaped Roughness Elements Having Central Gaps on the Absorber Plate of Solar Air Heater

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Navneet Kumar Pandey ◽  
Vijay Kumar Bajpai
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Reynolds Number ◽  
Friction Factor ◽  
Angle Of Attack ◽  
Solar Air Heater ◽  
Maximum Enhancement ◽  
Friction Characteristics ◽  
Air Heater ◽  
Circular Arcs

Thermal performance of solar air heater does not take into account the energy loss due to friction for propelling air through the duct. In this work, an experimental investigation has been carried out to study the effect of heat transfer and friction characteristics of turbulent flow of air passing through rectangular duct which is roughened by circular arcs having gaps of 2 mm in between arranged in angular fashion, and the roughened wall is uniformly heated. The thermal and friction characteristics are governed by duct aspect ratio (W/H), hydraulic diameter (D), and relative roughness pitch (P/e), angle of attack of angular arc (α), and Reynolds number (Re). Experiments encompassed the Reynolds number ranges from 3600 to 15,100, P/e ranges from 6 to 20, and angle of attack of angular arc of flow over the protrusions ranges from 15 deg to 75 deg. The results have also been compared to W-shaped roughness inclined at 45 deg. The maximum enhancement in heat transfer and friction factor is 3.15 and 3.93 times as compared with smooth duct. Arc with gaps have also been observed to be better than their W-shaped counterparts. These experimental results have been used to study their influence on Nusselt number and friction factor, and empirical relations have been derived using regression analysis.

Experimental Investigation of Enhanced Heat Transfer and Pressure Drop in a Solar Air Heater Duct With Discretized Broken V-Rib Roughness

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
Anil Kumar Patil ◽  
J. S. Saini ◽  
Krishna Kumar
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Geometrical Parameters ◽  
Solar Air Heater ◽  
Enhanced Heat Transfer ◽  
Transfer Rates ◽  
Air Heater ◽  
Effective Efficiency ◽  
Flow Through ◽  
Considerable Enhancement

The present study examines the augmentation in heat transfer and friction in a flow through solar air heater duct with discretized broken V-rib roughness. The experimental outcomes pertaining to Reynolds number from 3000 to 17,000, relative gap position (s′/s) from 0.2 to 0.8, relative staggered rib position (p′/p) from 0.2 to 0.8 have been presented and discussed. Discretized broken V-rib roughness brought out considerable enhancement in heat transfer rates over V-rib roughness and smooth duct. Effective efficiency of discretized broken V-rib roughened solar air heater is estimated and geometrical parameters of roughness are optimized with regard to temperature rise parameter and insolation.

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