Library Subscription: Guest
Home Archives Officers Future meetings Assembly for International Heat Transfer Conferences
International Heat Transfer Conference 9

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

AN INVESTIGATION OF BOILING HEAT TRANSFER IN FIBROUS POROUS MEDIA

Gary R. Rudemiller
Engineeing Division, The Institute of Paper Science and Technology Atlanta, GA, USA

Jeffrey D. Lindsay
Engineeing Division, The Institute of Paper Science and Technology Atlanta, GA, USA

DOI: 10.1615/IHTC9.3390
pages 159-164

Abstract

Boiling phenomena are investigated in the presence of porous media composed of ceramic fibers ranging in diameter from 3.0 to 18.5 μm for system pressures ranging from 0.18 to 0.28 MPa. Bed porosities range from 0.935 to 0.95, average pore diameters range from 30 to 250 μm, and permeabilities range from 2 × 10−11 to 6 × 10−9 m2. For surface temperatures up to 400°C, measured boiling curves for water in the different fiber beds show maximum heat fluxes on the order of 25 W/cm2. The boiling curves exhibit two distinct regimes - a nucleate-type regime and a constant heat flux regime. In the nucleate-type regime, heat flux is directly related to wall superheat, and the slope is directly related to the average pore diameter of the bed. In the constant flux regime, heat flux is independent of wall superheat, as heat transfer is governed by the rate at which the fiber bed supplies water to the heater surface. The transition region can exhibit a peak heat flux and associated rapid escalation in surface temperature similar to burnout in classical pool boiling.
Correlations based on dimensional analysis are presented for both regimes. Data in the constant flux regime are fitted to ± 35%, but data in the nucleate-type regime are only fitted to ± 175%.

Purchase $25.00 Check subscription Publication Ethics and Malpractice Recommend to my Librarian Bookmark this Page