Abstract

This study presents the geometrical optimization of a solar air heater. A reasonable working range of geometrical parameters: length 1–3 m, width 0.1–0.5 m, and height 0.005–0.05 m (or aspect ratio 1–20), is investigated as per general applications and installation constraints. The effect of these geometrical parameters on thermal (heat flux and outlet air temperature) and hydraulic (air velocity, mass flowrate, pressure loss and pumping power, and Bejan number) parameters are theoretically studied. Later, a numerical investigation is carried out with an optimum geometry of SAH-duct (length 2.44 mm and width 0.3 m), for aspect ratio 4–18 and Re 3000–15,000. An experimental study is also done to validate numerical results. The heat transfer and frictional loss do not show a significant change in the values for the aspect ratio 8–12.

References

References
1.
Chhaparwal
,
G.
,
Srivastava
,
A.
, and
Dayal
,
R.
,
2019
, “
Artificial Repeated-Rib Roughness in a Solar Air Heater – A Review
,”
Sol. Energy
,
194
, pp.
329
359
. 10.1016/j.solener.2019.10.011
2.
Charters
,
W. W.
,
1971
, “
Some Aspects of Flow Duct Design for Solar-Air Heater Applications
,”
Sol. Energy
,
13
(
2
), pp.
283
288
. 10.1016/0038-092X(71)90009-0
3.
Hollands
,
K. G. T.
, and
Shewen
,
E. C.
,
1981
, “
Optimization of Flow Passage Geometry for Air-Heating, Plate-Type Solar Collectors
,”
ASME J. Sol. Energy Eng.
,
103
(
4
), p.
323
. 10.1115/1.3266260
4.
Bhargava
,
A. K.
,
Garg
,
H. P.
, and
Sharma
,
V. K.
,
1982
, “
Theoretical Analysis of Some Configurations of Double Exposure Solar Air Heaters
,”
Energy
,
7
(
4
), pp.
377
388
. 10.1016/0360-5442(82)90097-4
5.
Husain
,
M. S.
,
Tiwari
,
G. N.
, and
Garg
,
H. P.
,
1985
, “
Performance of a Solar Collector/Storage Water Heater
,”
Appl. Energy
,
20
(
4
), pp.
301
316
. 10.1016/0306-2619(85)90020-0
6.
Rohsenow
,
W. M.
,
Hartnett
,
J. R.
, and
Cho
,
Y. I.
,
1998
,
Handbook of Heat Transfer
, 3rd ed.,
McGraw-Hill Education
,
New York
, pp.
1
1520
.
7.
Hartnet
,
J. P.
, and
Irvine
,
T. F.
, Jr.
,
1957
, “
Nusselt Values for Estimating Liquid Metal Heat Transfer in Noncircular Ducts
,”
AIChE J.
,
3
(
3
), pp.
313
317
. 10.1002/aic.690030305
8.
Jones
,
O. C.
,
1976
, “
An Improvement in the Calculation of Turbulent Friction in Rectangular Ducts
,”
ASME J. Fluids Eng.
,
98
(
2
), pp.
173
181
. 10.1115/1.3448250
9.
Murata
,
A.
, and
Mochizuki
,
S.
,
1999
, “
Effect of Cross-Sectional Aspect Ratio on Turbulent Heat Transfer in An Orthogonally Rotating Rectangular Smooth Duct
,”
Int. J. Heat Mass Transfer
,
42
(
20
), pp.
3803
3814
. 10.1016/S0017-9310(99)00058-7
10.
Chang
,
M. Y.
, and
Lin
,
T. F.
,
1998
, “
Experimental Study of Aspect Ratio Effects on Longitudinal Vortex Flow in Mixed Convection of Air in a Horizontal Rectangular Duct
,”
Int. J. Heat Mass Transf.
,
41
(
4–5
), pp.
719
733
. 10.1016/S0017-9310(97)00165-8
11.
Chang
,
S. W.
,
Chiang
,
K. F.
, and
Lin
,
C. Y.
,
2014
, “
Channel Aspect Ratio Effect on Thermal Performance of Air-Water Slug Flow Through U-Bend Channels
,”
Int. J. Therm. Sci.
,
76
, pp.
11
29
. 10.1016/j.ijthermalsci.2013.08.009
12.
Etemad
,
S.
, and
Mujumdar
,
A. S.
,
1994
, “
The Effect of Aspect Ratio and Rounded Corners on the Laminar Forced Convection Heat Transfer of a Non Newtonian Fluid in the Entrance Region of a Rectangular Duct
,”
Int. Commun. Heat Mass Transf.
,
21
(
2
), pp.
283
296
. 10.1016/0735-1933(94)90026-4
13.
Han
,
J.-C.
, and
Park
,
J. S.
,
1988
, “
Developing Heat Transfer in Rectangular Channels With Rib Tubulators
,”
Int. J. Heat Mass Transf.
,
31
(
1
), pp.
183
195
. 10.1016/0017-9310(88)90235-9
14.
Choi
,
H. S.
, and
Park
,
T. S.
,
2013
, “
The Influence of Streamwise Vortices on Turbulent Heat Transfer in Rectangular Ducts with Various Aspect Ratios
,”
Int. J. Heat Fluid Flow
,
40
, pp.
1
14
. 10.1016/j.ijheatfluidflow.2012.12.003
15.
Lee
,
P. S.
, and
Garimella
,
S. V.
,
2006
, “
Thermally Developing Flow and Heat Transfer in Rectangular Microchannels of Different Aspect Ratios
,”
Int. J. Heat Mass Transf.
,
49
(
17–18
), pp.
3060
3067
. 10.1016/j.ijheatmasstransfer.2006.02.011
16.
Schmidt
,
F. W.
,
1971
, “Private Communication,”
Tech. Rep
.,
Pennsylvania State University
,
University Park, PA
.
17.
Shah
,
R. K.
, and
London
,
A. L.
,
1971
, “Laminar Flow Forced Convection Heat Transfer and Flow Friction in Straight and Curved Ducts A Summary of Analytical Solutions,”
Tech. Rep
.,
Technical Report No. 75
,
Stanford University
,
Stanford, CA
.
18.
ANSYS, Inc.
,
2013
,
ANSYS Fluent Theory Guide
, Vol.
80
, Canonsburg, PA.
19.
ANSI/ASHRAE Standard 93-2010 (RA 2014)
,
Methods of Testing to Determine the Thermal Performance of Solar Collectors
.
You do not currently have access to this content.