Experimental investigation on heat transfer and frictional characteristics of wire coils inserts in transition flows at different Prandtl number
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 Num...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2005 |
| País: | España |
| Institución: | Universidad Politécnica de Cartagena(UPCT) |
| Repositorio: | Repositorio Digital UPCT |
| OAI Identifier: | oai:repositorio.upct.es:10317/606 |
| Acceso en línea: | http://hdl.handle.net/10317/606 |
| Access Level: | acceso abierto |
| Palabra clave: | Termohidráulica Número 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 Mecánica de Fluidos |
| Sumario: | 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 unstabilities in flow, due to the swirl flow induced by the wires. |
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