Experimental Study of High Weber Number Impact of Methoxy-Nonafluorobutane C4F9OCH3 (HFE-7100) and n-Heptane Droplets on a Heated Solid Surface.
Experimental Study of High Weber Number Impact of
Methoxy-Nonafluorobutane C4F9OCH3 (HFE-7100) and
n-Heptane Droplets on a Heated Solid Surface.
(778 K)
Manzello, S. L.; Yang, J. C.
International Journal of Heat and Mass Transfer, Vol.
45, No. 19, 3961-3971, September 2002.
Keywords:
droplets; fire suppression
Abstract:
An experimental study is presented for
methoxy-nonafluorobutane (C4F9OCH3, HFE-7100) droplet
impingement on a heated solid surface. The impaction
process was recorded using a high-speed digital camera
at 1000 frames per second. The initial droplet diameter
was fixed at 1.7 mm 0.1 mm, and all experiments were
performed in atmospheric air. The impact velocity was
fixed at 2.0 m/s thus defining an impact Weber number of
750. The impacted solid surface was made of polished
stainless steel. The droplet evaporation lifetime was
measured as a function of temperature to determine the
Leidenfrost temperature of HFE-7100. The temperature of
the stainless steel surface was varied from 20 C to
above the Leidenfrost temperature of HFE-7100.
Experiments were also performed using n-heptane to
investigate whether the collision dynamics were similar
if the impact Weber number was matched to HFE-7100 and
collision considered within the same boiling regimes as
HFE-7100. While the collision dynamics were
qualitatively similar, the evolution of liquid film
diameter with time was different. Thus, the evolution of
liquid film diameter with time must be measured for a
particular fluid. Existing models used to describe the
evolution of liquid film diameter with time were found
to be inadequate to describe HFE-7100 and n-heptane
impact.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899