Experimental Study of the Effects of Rib Angle and Discretization on Heat Transfer and Friction in an Asymmetrically Heated Rectangular Duct

Karwa, Rajendra; Bairwa, R. D.; Jain, Bhavesh; Karwa, Nitin

doi:10.1615/jenhheattransf.v12.i4.40

Cited by 55 publications

(15 citation statements)

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“…4 shows the variation of plate and air temperature along the length of the absorber plate. This variance in temperature is in accord with the work of Gupta et al [5], Momin et al [10] and Karwa et al [18]. All data were measured under steady state condition.…”

Section: Experimental Setup and Proceduressupporting

confidence: 89%

Heat transfer and fluid flow behaviour of a rectangular duct roughened with V-ribs with symmetrical gaps

Maithani

Saini

2015

International Journal of Ambient Energy

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In the present work artificial roughness in the form V-ribs with symmetrical gaps have been applied on the heated surface to enhance the heat transfer in the limbs of V-ribs. Symmetrical gaps on both legs were provided by varying the relative gap width from 1 to 5 and number of gaps from 1 to 5. The relative roughness pitch, relative roughness height and aspect ratio of the rectangular duct are kept constant to the value of 10, 0.0433 and 12, respectively. The Nusselt number and friction factor of the artificially roughened absorber plates has been determined experimentally and corresponding values were compared with that of the smooth duct for the range of flow Reynolds number 4000-18000. The maximum enhancement in Nusselt number was reported for relative gap width of 4 and Number of gaps of 3. The thermohydraulic enhancement factor was found to be in order of the 1.54-2.39. IntroductionThe demand of producing more and more energy and depleting fossil fuels due to increasing population, industrialization and urbanization gives rise to develop highly efficient renewable thermal systems. Out of many renewable energy resources, solar energy is one of the most conspicuous and non exhaustible sources of energy source and have potential to fulfil daily energy need. Flat plate solar energy collector is the most elementary and the cheapest heat exchanger widely used for air heating applications. Flat plate collector is heated by exposing it to solar radiation and heat is transferred to the air flowing through the system mainly by convection. Due to low heat transfer coefficient between absorber plate and flowing air, the efficiency of solar air heater is considerably low. To make solar air heater more efficient, heat transfer rate from the absorber plate to flowing air need to be increased.

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Section: Experimental Setup and Proceduressupporting

confidence: 89%

Heat transfer and fluid flow behaviour of a rectangular duct roughened with V-ribs with symmetrical gaps

Maithani

Saini

2015

International Journal of Ambient Energy

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“…It was obtained that inclination of rib results generation of vortices and secondary flow which affect value of heat transfer as compared to the continuous ribs. With the continuous research over solar air heater roughness further enhancement in effectiveness of solar air heaters, studies were performed by applying discrete rib roughness in various configurations such as V-shaped discrete (i.e., [8]), V-up and V-down discrete rib arrangements (i.e., [9]) and staggered discrete V-shaped ribs (i.e., [10]) In all these arrangements V-down discrete arrangement gives the best heat transfer performance but at the expanse of large friction losses. To reduce frictional losses investigator, introduce gaps with in the roughness geometries; viz.…”

Section: Introductionmentioning

confidence: 99%

Exergetic Performance Evaluation and Comparative Study of A Roughened Solar Air Heater using MATLAB

Kumar¹,

Bisht²

2017

IJERT

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“…It was reported that the inclination of 60 o on rib gives better performance as compare to the transverse roughness. Another experimental study using V-discrete and Vdiscontinuous roughness was done by Karwa et al [11]. Singh et al [12] did his investigation with discrete V-down roughness.…”

Section: Introductionmentioning

confidence: 99%

Improved Thermal Performance of Solar Air Heater Using V-Rib with Symmetrical Gap and Staggered Rib

Jain¹

2017

IJERA

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The most efficient technique to increase the performance of solar air heater is to enhance the heat transfer by using artificial roughness in form of repeatedly used ribs on the absorbing heated absorber plate. In order to analyse the thermal performance and flow pattern of rectangular duct with aspect ratio (W/H) of 8, the present experimental investigation is performed with V-rib with Symmetrical Gap and Staggered Rib. The experiment has covered a Reynolds number (Re) range of 3000-14000, rib height 2 mm, pitch (P) 24mm, relative roughness pitch (P/e) of 12, gap width (g) 8mm, relative gap width (g/e) as 4 and angle of attack (α) 60 o , number of gaps on each sides of V-rib (Ng) 3, relative roughness height (e/Dh) 0.045, staggered rib pitch (P') 15.6mm, relative staggered rib pitch (P'/P) 0.65, staggered rib size (w) 20mm and relative staggered rib size (w/g) 2.5. Results have been compared with the smooth plate under similar flow condition to determine the enhancement in heat transfer and improvement in efficiency. Relative staggered rib pitch was kept at 0.65 and staggered rib size was kept as 2.5 times gap width.

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Experimental Study of the Effects of Rib Angle and Discretization on Heat Transfer and Friction in an Asymmetrically Heated Rectangular Duct

Cited by 55 publications

References 0 publications

Heat transfer and fluid flow behaviour of a rectangular duct roughened with V-ribs with symmetrical gaps

Heat transfer and fluid flow behaviour of a rectangular duct roughened with V-ribs with symmetrical gaps

Exergetic Performance Evaluation and Comparative Study of A Roughened Solar Air Heater using MATLAB

Improved Thermal Performance of Solar Air Heater Using V-Rib with Symmetrical Gap and Staggered Rib

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