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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

EXPERIMENTAL INVESTIGATION OF TWO-PHASE FLOW BOILING INSIDE POROUS MEDIA

Get access (open in a dialog) DOI: 10.1615/IHTC16.bae.023421
pages 1199-1206

Sinopsis

The presented work aims to verify the in-tube-applicability and benefit of integrating metal sponges (open-cell metal foams) for flow boiling of CO2 in a horizontal tube. The highly porous network structure of sponges and the continuity of both solid and fluid phase allow for an improved fluid mixing and may increase the amount of nucleation sites at low pressure drops.
A test section for precisely measuring the heat transfer coefficient and pressure drop of CO2 in a horizontal tube was designed. The tube's specific design results in the capability to determine the heat transfer coefficients at different circumferential and axial positions integrating different kind of sponges for a wide range of operating parameters.
The test section was successfully validated with both smooth tube in-house data for flow boiling of CO2 and well-known correlations for heat transfer. The flow boiling of CO2 in cylindrical copper sponges with a diameter of 14 mm, a porosity of 90 % and a cell density of 10 pores per inch was characterized. The use of sponges can shift the prevalence of a completely wetted apex to lower mass fluxes and vapor qualities in comparison to smooth tubes, increasing the heat transfer especially at these conditions. Observed flow patterns, pressure drops, and heat transfer coefficients are contextualized within the previous observations in literature. Models, based on well-established correlations but new in combination, can describe the results and are discussed with respect to their applicability and physical justifiability.