Absorbers are the prime heat transfer components of solar energy devices. The effects of variable edge loss coefficients on heat transfer performance of flat-plate solar absorbers are examined. From fundamental energy relations, an edge loss coefficient is obtained which embodies the geometric and ambient parameters for estimating the edge heat loss. This model is similar in form to that given by Kaligrou (2009, Solar Energy Engineering Processes and Systems, Elsevier, New York, pp. 156–163) but differs from that obtained by Duffie and Beckman (1991, Solar Engineering of Thermal Processes, Wiley & Sons, Inc., New York), which can be corrected by employing a correction factor given here. The results confirm that the edge loss can significantly affect the absorber performance depending on Ae/Ap ratios, and the prevailing ambient conditions. However, previous models neglect these effects. It is found that the model given by Duffie and Beckman erroneously exceeds the total energy input and overestimates the loss by as much as a factor of 6, which goes against the first law of thermodynamics. When the correction factor is applied, the model gives a better approximation.

References

1.
Goyal
,
R. K.
, and
Tiwari
,
G. N.
, 1997, “
Parametric Study of a Reverse Flat Plate Absorber Cabinet Dryer: A New Concept
,”
Sol. Energy
,
60
(
1
), pp.
41
48
.
2.
Grossmana
,
G.
,
Shitzera
,
A.
, and
Zvirina
,
Y.
, 1977, “
Heat Transfer Analysis of a Flat-Plate Solar Energy Collector
,”
Sol. Energy
,
19
(
5
), pp.
493
502
.
3.
Liu
,
Y.-D.
,
Diaz
,
L. A.
, and
Suryanarayana
,
N. V.
, 1984, “
Heat Transfer Enhancement in Air-Heating Flat-Plate Solar Collectors
,”
ASME J. Sol. Energy Eng.
,
106
(
3
), pp.
358
364
.
4.
Gorla
,
R. S. R.
, 1997, “
Finite Element Analysis of a Flat Plate Solar Collector
,”
Finite Elem. Anal. Design
,
24
(
4
), pp.
283
290
.
5.
Annino
,
A.
, 1983, “
A Dynamic Simulation of a Flat Plate Collector System
,”
Nuovo Cimento B
,
74
(
2
), pp.
139
150
.
6.
Garg
,
H. P.
,
Ram
,
C.
, and
Usha
,
R.
, 1981, “
Transient Analysis of Solar Air Heaters Using Finite Difference Technique
,”
Energy Res.
,
5
, pp.
243
252
.
7.
Donatien
,
J.
, and
Michels
,
D.
, 2006, “
Sensitivity Analysis of Thermal Performances of Flat Plate Solar Air Heaters
,”
Heat Mass Transfer
,
42
, pp.
1065
1081
.
8.
Mullick
,
S. C.
, and
Samdarshi
,
S. K.
, 1988, “
An Improved Technique for Computing the Top Heat Loss Factor of Flat-Plate Collector With a Single Glazing
,”
ASME J. Sol. Energy Eng.
,
110
, pp.
262
267
.
9.
Agarwal
,
V. K.
, and
Larson
,
D. C.
, 1981, “
Calculation of Top Heat Loss Coefficient of a Flat-Plate Solar Collector
,”
Sol. Energy
,
27
, pp.
69
71
.
10.
Hollands
,
K. G. T.
, and
Wright
,
J. L.
, 1983, “
Heat Loss Coefficient and Effective Transmittance-Absorptance Product for Flat Plate Collectors With Diathermanous Covers
,”
Sol. Energy
,
30
(
3
), pp.
211
216
.
11.
Duffie
,
J. A.
, and
Beckman
,
W. A.
, 1991,
Solar Engineering of Thermal Processes
,
Wiley & Sons, Inc.
,
New York
.
12.
Hilton
,
D. V.
, 2004,
Fundamentals of Finite Element Analysis
,
McGraw-Hill
,
New York
.
13.
Kalogirou
,
S. A.
, 2009,
Solar Energy Engineering Processes and Systems
,
Elsevier
,
New York
, pp.
156
163
.
14.
Heaton
,
H. S.
,
Reynolds
,
W. C.
, and
Kays
,
W. M.
, 1964, “
Heat Transfer in Annular Passages Simultaneous Development of Velocity and Temperature Fields in Laminar Flow
,”
Int. J. Heat Mass Transfer
,
7
(
7
), pp.
763
781
.
15.
Sparrow
,
E. M.
,
Ramsey
,
J. W.
, and
Mass
,
E. A.
, 1979, “
Effect of Finite Width on Heat Transfer and Fluid Flow About an Inclined Rectangular Plate
,”
ASME J. Heat Transfer
,
101
(
2
), pp.
199
204
.
16.
McAdams
,
W. H.
, 1954,
Heat Transmission
, 3rd ed.,
McGraw-Hill
,
New York
.
17.
Nwosu
,
P. N.
, 2011, “
Edge Correction Heat Loss Analysis in a Solar Air Heater Using Finite Element Method
,” Ph.D. thesis, University of Nigeria, Nsukka.
18.
Janjai
,
S.
, and
Tung
,
P.
, 2006, “
Performance of a Solar Dryer Using Hot Air From Roof-Integrated Solar Collectors for Drying Herbs and Spices
,”
Renewable Energy
,
30
(
14
), pp.
2085
2095
.
19.
Kind
,
R. J.
,
Gladstone
,
D. H.
, and
Moizer
,
A. D.
, 1983, “
Convective Heat Losses From Flat-Plate Solar Collectors in Turbulent Winds
,”
ASME J. Sol. Energy Eng.
,
105
(
1
), pp.
80
85
.
You do not currently have access to this content.