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Influence of wall material on nucleate pool boiling of liquid nitrogen

Bombardieri, C. and Manfletti, C. (2014) Influence of wall material on nucleate pool boiling of liquid nitrogen. 32nd UIT Heat Transfer Conference, 23. - 25. June 2014, Pisa, Italy.

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Abstract

The wall material thermal conductivity k is one of the surface characteristics that influences the pool boiling heat transfer coefficient (HTC). It is believed that growth rates of vapor bubbles and their frequency are mechanisms affected by the thermal conductivity. In order to investigate this effect, different surface materials (copper, aluminum, stainless steel) are tested in a horizontal surface geometry. From a physical point of view, the redistribution of local heat fluxes between the free surface (wet by the liquid) and the spot covered with nucleation centers is hindered in the case of low values of k. But the wall material k affects the nucleate boiling curve only in the case of a very limited number of nucleation sites. Previous experiments in fact concluded that for a rough surface that has a larger number of vapor generating centers, the wall thermal conductivity does not significantly affect the boiling HTC; therefore the tested surfaces are mechanically polished to avoid any roughness effect. In this paper, nucleate pool boiling curves of saturated nitrogen under ambient pressure are experimentally obtained on a horizontal flat surface and the effect of three different wall materials is evaluated. Hysteresis behaviour has been observed for the copper and aluminum surfaces, while the results for stainless steel are contradictory. The critical heat flux (CHF) is also compared and analyzed by taking into account the thermal effusivity of the different materials. Finally, experimental results are compared against the most common empirical correlations for nucleate pool boiling heat transfer.

Item URL in elib:https://elib.dlr.de/92184/
Document Type:Conference or Workshop Item (Speech)
Title:Influence of wall material on nucleate pool boiling of liquid nitrogen
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Bombardieri, C.Cristiano.Bobardieri (at) dlr.deUNSPECIFIED
Manfletti, C.Chiara.Manfletti (at) dlr.deUNSPECIFIED
Date:2014
Refereed publication:No
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:pool boiling; nucleate boiling; liquid nitrogen
Event Title:32nd UIT Heat Transfer Conference
Event Location:Pisa, Italy
Event Type:international Conference
Event Dates:23. - 25. June 2014
Organizer:University of Pisa
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Transport
DLR - Research area:Raumfahrt
DLR - Program:R RP - Raumtransport
DLR - Research theme (Project):R - Antriebsystemtechnik - Schubkammertechnologie
Location: Lampoldshausen
Institutes and Institutions:Institute of Space Propulsion > Rocket Propulsion
Deposited By: Hanke, Michaela
Deposited On:25 Nov 2014 07:47
Last Modified:25 Nov 2014 15:34

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