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NASA NTRS · 20260001409

Decoupling Surface Topography from Gravitational Acceleration in Cryogenic Pool Boiling

Mohammad S Reza·Philip Ignatoff·Jimmy Almacddissi·Jason Hartwig·J N Chung·Youngsup Sung
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Abstract

Boiling heat transfer is governed by a complex interplay between surface conditions and gravitational acceleration. To isolate the sole effects of gravity, we investigated the pool boiling characteristics of liquid nitrogen on atomically smooth silicon dioxide (SiO 2 ) surfaces under terrestrial (1-g) and reduced gravity (0±0.02 g) conditions achieved via parabolic flight. Our results quantify a drastic reduction in the critical heat flux (CHF) in reduced gravity, decreasing from 16.15 W/cm 2 at 1-g to 5−6 W/cm 2 at μ-g due to the suppression of buoyancy. Conversely, we observed a distinct increase in the heat transfer coefficient (HTC) in the reduced gravity condition prior to CHF. By utilizing a surface with a maximum peak-to-valley height of ≈36.7 nm and low contact angle hysteresis (<10°), we confirm this HTC enhancement is an intrinsic response to the gravitational environment, decoupled from surface-defect-induced nucleation. These findings demonstrate that the influence of surface topography is significantly more prominent in reduced gravity than in terrestrial conditions, providing a critical baseline for rationalizing the design of cryogenic thermal management systems in space and quantum applications.

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Mohammad S Reza, Philip Ignatoff, Jimmy Almacddissi, Jason Hartwig, J N Chung, Youngsup Sung. 2026-07-08. Decoupling Surface Topography from Gravitational Acceleration in Cryogenic Pool Boiling. https://ntrs.nasa.gov/citations/20260001409

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