bubble, occurs on small heaters in
microgravity. It is found that once a
stationary, coalesced bubble covers the
heater, a small change in the gravity level
would only change the bubble shape
without significantly affecting the steady
state value of heat transfer. By comparison,
if the gravity levels continuously fluctuate
as is the case in parabolic flights where the
g-jitter values are relatively large, the
resulting continuous adjustments in bubble
shape can produce flow around the bubble
increasing the heat transfer. In essence, the
fluctuation in acceleration (g-jitter) affects
heat transfer more than the absolute value
of acceleration in the SDB case.
Microgravity heat transfer predictions
based on modified scaling law and taking
into account g-jitter effects were shown to
be in excellent agreement with
experimental data. This is one of the most
significant findings of the current work
performed under space microgravity
environments and may address the widely discussed problem of the effect of g-jitter on pool
boiling studies (Rishi 2012).
PUBLICATION(S)
Raj R, Kim J, McQuillen J. Pool boiling heat transfer on the International Space Station:
Experimental results and model verification. Journal of Heat Transfer. 2012;134(10). doi:
10.1115/1.4006846.
This investigation is complete and all results are published.
Microheater Array Boiling Experiment Image: High-
speed, time-lapse imagery documenting nucleation of
three separate vapor bubbles (top image), coalescence
of the middle and right bubble (middle image), and finally
after all the vapor bubbles have merged. NASA image.