Experimental investigation on heat transfer and frictional characteristics of wire coils inserts in transition flows at different Prandtl number
Knowledge Area
Mecánica de FluidosPublication date
2005Publisher
Elsevier ScienceBibliographic Citation
GARCÍA , Alberto, VIECENTE, Pedro G., VIEDMA, Antonio. Experimental study of heat transfer enhancement with wire coil inserts in laminar-transition-turbulent regimes at different Prandtl numbers. International Journal of Heat and Mass Transfer, 48: 4640-4651, 2005. ISSN 0017-9310Keywords
TermohidráulicaNúmero de Reynolds
Turbulencias inducidas por corrientes
Número Prandtl
Transferencia de calor
Thermohydraulics
Turbulent flows
Reynolds number
Turbulence induced currents
Prandtl number
Heat transfer
Flujos turbulentos
Abstract
Helical-wire-coils inserted in a round tube have been experimentally studied in other to obtain their thermohydraulic behaviour in laminar, transition and turbulent flows. Using water and propylene glycol mixtures at different concentrations, a wide range of flow conditions was covered: Reynolds Number from 100 to 90 000 and Prandtl number from 2.8 to 200. Six Wire coil insets were tested, with a geometric range of helical pitch 1.17 less than p/e less than 33 and helix angle 30º less than infinity less than 53º. Wire coils were tightly attached to the inner tube surface. Experimental correlations of Fanning friction factor and Nusselt number as functions of flow and dimensionaless geometric parameters are proposed. Results show that wire colis increse pressure drop up to 8 times and heat transfer up to 4 times compared to the empty smooth tube. Moreover these insert devices accelerate transition to critical Reynolds numbers down to 700. Transition to turbulent flow occurs softly without ...
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