Gas-Liquid Phase Separation in Microgravity Tiffany Boney, Professor Boris Khusid, Rai Munoz, Ian Peczak, Dana Qasem New Jersey Insitute of Technology, NASA Goddard Institute for Space Studies, New York City Research Institute

1
Electrohydrodynamic Gas-Liquid Phase Separation
in MicrogravityTiffany Boney, Dr. Boris Khusid,
Rai Munoz, Ian Peczak, Dana QasemOtto H. York
Department of Chemical, Biological, and
Pharmaceutical Engineering New Jersey Institute
of Technology, Newark, NJ 07102
Abstract
Materials and Methodology
Materials and Methodology The experimental
setup consisted of two setups Module 1 and
Module 2. Module 1 was comprised of a
programmable function generator placed on top of
a high-voltage amplifier. Module 2 consisted of
samples of water and HFE-7100 in two quartz
cuvettes. A thermistor, powered by DC generators,
was enclosed in a silicon-based PDMS insulating
layer and placed at the bottom of each cuvette.
Stainless-steel electrodes insulated in Teflon
were inserted into each cuvette so as not to
touch the PDMS layer. The cuvettes were monitored
using video recording equipment, which consisted
of an LED backlight illumination (placed behind
the cuvettes), a camera with a lens and mount,
and uc480 video software. Data was collected
using a LabJack U6-Pro Data Logger. Both data and
video footage were saved on the hard drive of a
PC. A square wave function was programmed
into the function generator to produce an AC
voltage electric field. The voltage (in kV) and
frequency (in Hz) of the electric field were
varied in order to observe their effects on heat
transfer in HFE-7100 and water. Electric fields
of 3kV and 4kV were tested, each at frequencies
of 1Hz, 10Hz, and 20Hz. Samples of HFE-7100 and
water were also tested without an electric
field.
Abstract This report presents the validation
of a novel electro-hydrodynamic (EHD) technology
for two-phase separation in microgravity. In an
environment with Earth gravity, gas-liquid phase
separation readily occurs as a result of buoyancy
forces. However, in a microgravity environment,
bubbles do not rise out of a fluid due to the
viscosity of the fluid and the absence of the
buoyant force, leading to bubble coalescence, and
the formation of gas pockets during transfers of
bulk liquids. This presents a problem to
life-sustaining systems and biomedical research
as it can lead to failure in the storage,
analysis and transportation of two-phase systems.
The main goal of the project is the study of
bubble dynamics in fluids subjected to electric
fields.
Field off
Field on
Figure 4 (Below). When electric field was turned
on, temperature decreased and reached a steady
state profile with a uniform distribution of heat.
Figure 3 (Above). Electric field is switched on
and off at 10 second intervals. Temperature
decreased each time electric field was switched
on.
Introduction
Introduction The objective of the project is to
utilize a novel method of EHD found in an
ensemble of air bubbles driven by interplay of
electric and hydrodynamics forces. The experiment
contrasts to previous experiments studying EHD.
Previous experiments utilized only the
dielectrophoretic force, the force a non-uniform
electric field exerts on a particle in a
dielectric medium, to substitute for buoyancy
effects. This force only manifests
when the medium and the particle have different
polarizabilities. If the polarizability of the
particle is greater than the medium, a positive
force towards the higher electric field gradient
is observed. If the polarizability is lower, then
a negative force in the direction of the lower
field gradient is observed. In the case of
bubbles, a negative force is experienced as
bubbles have a lower polarizability than their
dielectric medium. This provides an adequate
substitute for the effects of gravity.
The experiment employs oscillatory fluid flow
along with the dielectrophoretic force, which,
when exerted on bubbles, more heavily influence
the displacement in microgravity. This enables an
improvement of two-phase separation to be
achieved in comparison to current techniques.
The cycles of heating with and without an
electric field were as follows
Figure 1 Schematic of the EHD device in
ground-based tests 1, fluid cell 2, imaging
system 3, data acquisition system 4, high
voltage AC amplifier controlled by a programmable
function generator 5, grounded electrode 6, two
mini-heaters 7, Bubbles 8, Liquid 9, Fluid
cell (cuvettes) 10, energized electrode with
insulated tip.

• Conclusions
• Buoyancy force dominated electric field in the
  vertical displacement of bubbles. However,
  horizontal displacement of bubble trajectories
  were observed when field was switched on.
• Decrease in temperature was observed when
  electric field was turned on suggesting fluid
  flow at the heaterliquid interface
• Further Research
• A suspension of neutrally-buoyant particles in
  HFE-7100 and water may be used to mimic bubbles
  in terrestrial experiments and observe the effect
  of field on particle motion.
• Investigations will be conducted in microgravity
  to determine the effect of electric field on the
  motion of vapor bubbles in the absence of
  buoyancy force.

Conclusions
Figure 2 Video footage of the formation of
bubble columns with and without an electric
field, at 4kV/1Hz. The method of testing was 40
seconds of heating without a field, and 40
seconds of heating with field, followed by 40
seconds with both heater and field switched off.
Further Research
Temperature Data Calculations The temperature of
the heater, TH can be calculated from the circuit
depicted right. This temperature is assumed to be
the temperature of the liquid-boundary layer. V
is the total circuit voltage, I is the current,
VR the voltage across the resistor while R and RH
are the resistances of the resistor and the
heater, respectively.
Works Cited

• Works Cited
• S.W. Ahmad, T.G. Karayiannis, D.B.R. Kenning, A.
  Luke, Compound effect of EHD and surface
  roughness in pool boiling and CHF with R-123
  (2011) 1994-2003
• D. A. Saville, ELECTROHYDRODYNAMICS The
  Taylor-Melcher Leaky Dielectric Model (1997)
  27-64
• S. Siedel, S. Cioulachtjian, A.J. Robinson, J.
  Bonjour, Electric field effects during nucleate
  boiling from an artificial nucleation site (2011)
  762-771
• Y. Hristov, Zhao, D. B. R. Kenning, K. Sefiane,
  T. G. Karayiannis, A study of nucleate boiling
  and critical heat flux with EHD enhancement
  (2009) 9991017
• R. DeLombard, E. M. Kelly and K. Hrovat, E. S.
  Nelson, D. R. Pettit, Motion of Air Bubbles in
  Water Subjected to Microgravity Accelerations
  (2006)
• Green, Nicolas G. "Dielectrophoresis and AC
  Electrokinetics".Electrokinetics and
  Electrohydrodynamics in Microsystems. CISM
  Courses and Lectures (2011) 61-84

Sponsors National Aeronautics and Space
Administration (NASA) NASA Goddard Space Flight
Center (GSFC) NASA Goddard Institute for Space
Studies (GISS) NASA New York City Research
Initiative (NYCRI) New Jersey Institute of
Technology (NJIT) Contributors Dr. Boris
Khusid, Dr. John Tang, Dr. Ezinwa Elele Dana
Qasem Ian Peczak, High School Student Tiffany
Boney, High School Teacher Rai Munoz,
Undergraduate Student
Figure 2. Vapor bubbles are produced within water
subjected to a voltage of 3kV and frequencies of
1 and 20 Hz.