Abstract
This paper deals with the study of heat transfer in solar air heater consisting of winglet-shaped roughness on the absorber plate using liquid crystal thermography technique. The winglet-type roughness element was placed on the absorber surface of a rectangular channel solar air heater having an aspect ratio of 4. The absorber surface was heated uniformly by a constant heat flux of 800 W/m2. The non-dimensional roughness parameter considered was relative roughness pitch, i.e., P/e, and its values range between 5 and 12 with Reynolds number (Re) ranges between 6500 and 22,000. The value of angle of attack, i.e., alpha and relative roughness width (W/w) was kept constant, and the relative roughness pitch was varied to measure the heat transfer coefficient. The enhancement in heat transfer has been compared, and it is observed that at P/e of 8 for angle of attack (α) of 60 degrees resulting its optimum value. The enhancement of heat transfer with the increase in Reynolds number is also noted.
References
1.
Kumar
, S.
, and Tariq
, A.
, 2017
, “Steady State Experimental Investigation of Thermal Contact Conductance Between Curvilinear Contacts Using Liquid Crystal Thermography
,” Int. J. Therm. Sci.
, 118
(1
), pp. 53
–68
. 2.
Cooper
, T. E.
, Field
, R. J.
, and Meyer
, J. F.
, 1975
, “Liquid Crystal Thermography and Its Application to the Study of Convective Heat Transfer
,” ASME J. Heat Transfer
, 97
(1
), pp. 442
–450
. 3.
Stasiek
, J.
, Wierzbowski
, M.
, Klosowicz
, S.
, Zmija
, J.
, and Collins
, M. W.
, 2002
, Liquid Crystal Thermography for Technical and Biomedical Application
, WIT Press
, Southampton,UK
.4.
Ireland
, P. T.
, and Jones
, T. V.
, 2000
, “Liquid Crystal Measurements of Heat Transfer and Surface Shear Stress
,” Meas. Sci. Technol.
, 11
(7
), pp. 969
–986
. 5.
Won
, S. Y.
, and Ligrani
, P. M.
, 2004
, “Comparisons of Flow Structure and Local Nusselt Numbers in Channels With Parallel- and Crossed-Rib Turbulators
,” Int. J. Heat Mass Transfer
, 47
(1
), pp. 1573
–1586
. 6.
Tanda
, G.
, 2004
, “Heat Transfer in Rectangular Channels With Transverse and V-Shaped Broken Ribs
,” Int. J. Heat Mass Transfer
, 47
(2
), pp. 229
–243
. 7.
Ligrani
, P. M.
, 2000
, “Flow Visualization and Flow Tracking as Applied to Turbine Components in Gas Turbine Engines
,” Meas. Sci. Technol.
, 11
(7
), pp. 992
–1006
. 8.
Turner
, A. B.
, 1971
, “Local Heat Transfer Measurements on a Gas Turbine Blade
,” J. Mech. Eng. Sci.
, 13
(1
), pp. 1
–2
. 9.
Graham
, R. W.
, 1980
, “Fundamental Mechanisms That Influence the Estimate of Heat Transfer to Gas Turbine Blades
,” Heat Transfer Eng.
, 2
(1
), pp. 39
–47
. 10.
Cavallero
, D.
, and Tanda
, G.
, 2002
, “An Experimental Investigation of Forced Convection Heat Transfer in Channels With Rib Turbulators by Means of Liquid Crystal Thermography
,” Exp. Therm. Fluid Sci.
, 26
(2–4
), pp. 115
–121
. 11.
Tariq
, A.
, Swain
, S. K.
, and Panigrahi
, P. K.
, 2002
, “An Experimental Study of Convective Heat Transfer From Flat and Ribbed Surfaces
,” Ind. J. Eng. Mater. Sci.
, 9
(6
), pp. 464
–471
.12.
Chan
, T. L.
, Jambunathan
, K.
, and Leung
, T. P.
, 1994
, “A Surface Temperature Calibration Method for Thermochromic Liquid Crystals Using True-Colour Image Processing
,” Proceedings of the 10th International Heat Transfer Conference
, Brighton, UK
, Aug. 14–18
, Vol. 2, pp. 201
–206
.13.
Tanda
, G.
, 2001
, “Heat Transfer and Pressure Drop in a Rectangular Channel With Diamond-Shaped Elements
,” Int. J. Heat Mass Transfer
, 44
(18
), pp. 3529
–3541
. 14.
Kumar
, A.
, and Layek
, A.
, 2019
, “Nusselt Number and Fluid Flow Analysis of Solar Air Heater Having Transverse Circular Rib Roughness on Absorber Plate Using LCT and Computational Technique
,” Ther. Sci. Eng. Prog.
, 14
(1
), p. 100398
. 15.
Kumar
, A.
, and Layek
, A.
, 2018
, “Nusselt Number-Friction Characteristic for a Twisted Rib Roughened Rectangular Duct Using Liquid Crystal Thermography
,” Exp. Therm. Fluid Sci.
, 97
(1
), pp. 205
–217
. 16.
Gharai
, S. K.
, and Layek
, A.
, 2018
, “Heat Transfer Measurement in Rectangular Channel With Detach Ribs by Liquid Crystal Thermography
,” Int. J. Heat Technol.
, 6
(4
), pp. 1502
–1509
. 17.
Kumar
, A.
, and Layek
, A.
, 2020
, “Nusselt Number and Friction Factor Correlation of Solar Air Heater Having Winglet Type Vortex Generator Over Absorber Plate
,” Sol. Energy
, 205
(1
), pp. 334
–348
. 18.
Kumar
, A.
, and Layek
, A.
, 2020
, “Nusselt Number and Friction Characteristics of a Solar Air Heater That Has a Winglet Type Vortex Generator in the Absorber Surface
,” Exp. Therm. Fluid Sci.
, 23
(1
), p. 110204
. 19.
Kumar
, A.
, and Layek
, A.
, 2020
, “Evaluation of the Performance Analysis of an Improved Solar Air Heater With Winglet Shaped Ribs
,” Exp. Heat Transfer
, 34
(5
), pp. 1
–19
. 20.
Jain
, S. K.
, Agrawal
, G. D.
, and Mishra
, R.
, 2020
, “Experimental Investigation of Thermohydraulic Performance of the Solar Air Heater Having Arc-Shaped Ribs With Multiple Gaps
,” ASME J. Therm. Sci. Eng. Appl.
, 12
(1
), p. 011014
. 21.
Coleman
, H. W.
, and Steele
, W. G.
, 1999
, Experimentation and Uncertainty Analysis for Engineers
, 2nd ed., John Wiley & Sons
, New York
.22.
ASHRAE Standard
, 1977
, “Method of Testing to Determine the Thermal Performance of Solar Collector
,” ASHRAE, 34
(1
), pp. 93
–97
.23.
Bejan
, AD
, 2003
, Forced Convection Internal Flow in Ducts
, Heat Transfer Handbook
, pp. 395
–438
.24.
Bekele
, A.
, Mishra
, M.
, and Dutta
, S.
, 2011
, “Effects of Delta-Shaped Obstacles on the Thermal Performance of Solar Air Heater
,” Adv. Mech. Eng.
, 3
(13
), p. 103502
. 25.
Webb
, R. L.
, Eckert
, E. R. G.
, and Goldstein
, R. J.
, 1971
, “Generalized Heat Transfer and Friction Correlation for Tubes With Repeated Rib Roughness
,” Int. J. Heat Mass Transfer
, 14
(4
), pp. 601
–617
. Copyright © 2021 by ASME
You do not currently have access to this content.
