A numerical simulation of transient two-dimensional negatively buoyant flow into a straight baffle situated below an isothermal circular cylinder in an initially isothermal enclosure is presented for both an adiabatic and a highly conducting baffle for Rayleigh numbers from to . Results show the effects of baffle offset, width, and length on the point where viscous flow develops and on velocity profiles within the baffle. Results are interpreted to guide the design of straight baffles to reduce destruction of stratification in thermal stores using an immersed heat exchanger. The preferred geometry is a low-conductivity baffle of width equal to the effective width of the heat exchanger and 15 or more cylinder diameters in length to ensure nearly fully developed flow at the baffle outlet.
Issue Section:
Technical Briefs
1.
Khalillolahi
, A.
, and Sammakia
, B.
, 1986, “Unsteady Natural Convection Generated by a Heated Surface Within an Enclosure
,” Numer. Heat Transfer
0149-5720, 9
, pp. 715
–730
.2.
Farrington
, R. B.
, and Bingham
, C. E.
, 1987, “Testing and Analysis of Load-Side Immersed Heat Exchangers for Solar Domestic Hot Water Systems
,” National Renewable Energy Laboratory, Report No. SERI/TR-254-3094.3.
Lightstone
, M. F.
, Raithby
, G. D.
, and Hollands
, K. G. T.
, 1989, “Numerical Simulation of the Charging of Liquid Storage Tanks: Comparison With Experiment
,” ASME J. Sol. Energy Eng.
0199-6231, 111
, pp. 225
–231
.4.
Mote
, R.
, Probert
, S. D.
, and Nevrala
, D.
, 1991, “The Performance of a Coiled Finned-Tube Heat Exchanger Submerged in a Hot-Water Store: The Effect of the Exchanger’s Orientation
,” Appl. Energy
0306-2619, 38
, pp. 1
–19
.5.
Mote
, R.
, Probert
, S. D.
, and Nevrala
, D.
, 1991, “Free-Convective Flows Within a Hot-Water Store, Induced by a Submerged, Relatively Cold Heat Exchanger
,” Appl. Energy
0306-2619, 39
, pp. 207
–234
.6.
Reindl
, D. T.
, Beckman
, W. A.
, and Mitchell
, J. W.
, 1992, “Transient Natural Convection in Enclosures With Application to Solar Thermal Storage Tanks
,” ASME J. Sol. Energy Eng.
0199-6231, 114
, pp. 175
–181
.7.
Chauvet
, L. P.
, Nevrala
, D. J.
, and Probert
, S. D.
, 1993, “Heat Transfer Correlations for an Immersed Finned Heat Exchanger Coil Transferring Heat From a Hot Water Store
,” Appl. Energy
0306-2619, 44
, pp. 283
–314
.8.
Hahne
, E.
, and Chen
, Y.
, 1998, “Numerical Study of Flow and Heat Transfer Characteristics in Hot Water Stores
,” Sol. Energy
0038-092X, 64
, pp. 9
–18
.9.
Drück
, H.
, and Bachmann
, S.
, 2002, “Hot Water Performance of Solar Combistores—Description of a Test Method and the Experience Gained With the Application of the Method on Three Different Types of Combistores
,” Combisystems, IEA-SHC Task 26 Report, Oslo, pp. 47
–54
.10.
Liu
, W.
, Davidson
, J. H.
, Kulacki
, F. A.
, and Mantel
, S. C.
, 2003, “Natural Convection From a Horizontal Tube Heat Exchanger Immersed in a Tilted Enclosure
,” ASME J. Sol. Energy Eng.
0199-6231, 125
, pp. 67
–75
.11.
Liu
, W.
, Davidson
, J. H.
, and Kulacki
, F. A.
, 2004, “Natural Convection From a Tube Bundle in a Thin Inclined Enclosure
,” ASME J. Sol. Energy Eng.
0199-6231, 126
, pp. 702
–709
.12.
Liu
, W.
, Davidson
, J. H.
, and Kulacki
, F. A.
, 2005, “Thermal Characteristics of Prototypical Integral Collector Storage Systems With Immersed Heat Exchangers
,” ASME J. Sol. Energy Eng.
0199-6231, 127
, pp. 21
–28
.13.
Su
, Y.
, and Davidson
, J. H.
, 2005, “Natural Convection Heat Transfer in a Collector Storage With an Immersed Heat Exchanger: Numerical Study
,” ASME J. Sol. Energy Eng.
0199-6231, 127
, pp. 324
–332
.14.
Su
, Y.
, and Davidson
, J. H.
, 2007, “Multizone Porous Medium Model of Thermal/Fluid Processes During Discharge of an Inclined Rectangular Storage Vessel via an Immersed Heat Exchanger
,” ASME J. Sol. Energy Eng.
0199-6231, 129
, pp. 449
–457
.15.
Su
, Y.
, and Davidson
, J. H.
, 2007, “Transient Natural Convection Heat Transfer Correlations for Tube Bundles Immersed in a Thermal Storage
,” ASME J. Sol. Energy Eng.
0199-6231, 129
, pp. 210
–214
.16.
Mather
, D. W.
, Hollands
, K. G. T.
, and Wright
, J. L.
, 2002, “Single- and Multi-Tank Energy Storage for Solar Heating Systems: Fundamentals
,” Sol. Energy
0038-092X, 73
, pp. 3
–13
.17.
Ragoonanan
, V.
, Davidson
, J. H.
, Homan
, K. O.
, and Mantell
, S. C.
, 2006, “The Benefit of Dividing an Indirect Thermal Storage Into Two Compartments: Discharge Experiments
,” Sol. Energy
0038-092X, 80
, pp. 18
–31
.18.
Jordan
, U.
, Vejan
, K.
, Hilmer
, F.
, Knopf
, B.
, and Spieler
, A.
, 1998, “A Stratified Storage Tank With an Internal Thermosyphonically Driven Fin-Tube Heat Exchanger
,” Proceedings, EuroSun 1998
, III.3.6, pp. 1
–7
.19.
Jordan
, U.
, Vejan
, K.
, Knopf
, B.
, Spieler
, A.
, and Hilmer
, F.
, 1999, “Modeling of a Thermosyphonally Driven Discharge Unit of a Storage Tank
,” Proceedings, ISES Solar World Congress 1999
, Vol. 3
, pp. 197
–202
.20.
Drück
, H.
, 2002, “Influence of Different Combistore Concepts on the Overall System Performance
,” IEA-SHC Task 26, Industry Workshop
, Oslo, pp. 39
–46
.21.
Feiereisen
, T. J.
, Klein
, S. A.
, Duffie
, J. A.
, and Beckman
, W. A.
, 1982, “Heat Transfer From Immersed Coils
,” American Society of Mechanical Engineers, Paper No. 82 WA/SOL-18.22.
Mote
, R.
, Probert
, S. D.
, and Nevrala
, D.
, 1992, “Rate of Heat Recovery From a Hot-Water Store: Influence of the Aspect Ratio of a Vertical-Axis Open-Ended Cylinder Beneath a Submerged Heat-Exchanger
,” Appl. Energy
0306-2619, 41
, pp. 115
–136
.23.
Chauvet
, L. P.
, Nevrala
, D. J.
, and Probert
, S. D.
, 1993b, “Influences of Baffles on the Rate of Heat Recovery via a Finned-Tube Heat-Exchanger Immersed in a Hot-Water Store
,” Appl. Energy
0306-2619, 45
, pp. 191
–217
.24.
Altuntop
, N.
, Arslan
, M.
, Ozceyhan
, V.
, and Kanoglu
, M.
, 2005, “Effect of Obstacles on Thermal Stratification in Hot Water Storage Tanks
,” Appl. Therm. Eng.
1359-4311, 25
, pp. 2285
–2298
.25.
Zachar
, A.
, Farkas
, I.
, and Szlivka
, F.
, 2003, “Numerical Analysis of the Impact of Plates for Thermal Stratification Inside a Storage Tank With Upper and Lower Inlet Flows
,” Sol. Energy
0038-092X, 74
, pp. 287
–302
.26.
Kulacki
, F. A.
, Davidson
, J. H.
, and Hebert
, M.
, 2007, “On the Effectiveness of Baffles in Indirect Solar Storage Systems
,” ASME J. Sol. Energy Eng.
0199-6231, 129
, pp. 494
–498
.27.
Su
, Y.
, and Davidson
, J. H.
, 2008, “Discharge of Thermal Storage Tanks via Immersed Baffled Heat Exchangers: Numerical Model of Flow and Temperature Fields
,” ASME J. Sol. Energy Eng.
0199-6231, 130
, p. 021016
.28.
Haltiwanger
, J. F.
, and Davidson
, J. H.
, 2009, “Discharge of a Thermal Storage Tank Using an Immersed Heat Exchanger With an Annular Baffle
,” Sol. Energy
0038-092X, 83
(2
), pp. 193
–201
.29.
Wade
, A. D.
, Davidson
, J. H.
, and Haltiwanger
, J. F.
, 2009, “What is the Best Solution to Improve Thermal Performance of Storage Tanks With Immersed Heat Exchangers: Baffles or a Partitioned Tank?
,” ASME J. Sol. Energy Eng.
0199-6231, 131
(3
), p. 034503
.30.
Morgan
, V. T.
, 1975, “The Overall Convective Heat Transfer From Smooth Circular Cylinders
,” Adv. Heat Transfer
0065-2717, 11
, pp. 199
–264
.31.
Churchill
, S. W.
, and Chu
, H. H. S.
, 1975, “Correlating Equations for Laminar and Turbulent Free Convection From a Horizontal Cylinder
,” Int. J. Heat Mass Transfer
0017-9310, 18
, pp. 1049
–1053
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