Transcript Introduction to Research

Chapter 5
M.K. Mazumder, R. Sharma, A.S. Biris, M.N. Horenstein, J. Zhang,
H. Ishihara, J.W. Stark, S. Blumenthal and O. Sadder
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FIGURE 5.1 Dust devil formation on the dry lake area of the Mojave Desert.
Photo courtesy of Creative Commons Corporation, San Francisco, CA.
http://www.animalu.com/pics/photos.htm Jeff T. Alu
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FIGURE 5.2 Particle size distribution (shown in dark solid steps) of the test dust
as measured by using a Microtracparticle size analyzer. The line connecting the
dots shows the cumulative size distribution plotted as a function of particle
diameter in mm
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FIGURE 5.3 Normalized output power of a single crystal solar cell as a function
of mass concentration dust (mg/cm2) deposited on the front cover glass. A xenon
lamp was used to illuminate the solar cell. The mass median diameter of the dust
sample was approximately 9 mm
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FIGURE 5.4 Schematic of (a) single-phase EDS and (b) three-phase EDS
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FIGURE 5.5 A cross-sectional view of transparent parallel electrodes
embedded in a transparent film or glass panel. The electrodes are energized
by phased pulsed voltage for lifting and removing deposited dust particles
from the solar panels or mirrors
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FIGURE 5.6 A schematic layout of (a) single-phase (left diagram) and (b) threephase EDS (right diagram) electrodes
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FIGURE 5.7 Transparent EDS embedded in a transparent polyurethane (PU) film is
placed over a solar panel. The ITO electrodes are of triangular cross-section which
provides a more uniform distribution of the electric field compared with the field
distribution produced by electrodes of rectangular cross-section. The figure shows an
a-Si solar cell integrated with an EDS
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FIGURE 5.8 A three-phase power supply on a circuit board is shown connected to a
three-phase EDS screen. The electrodes are embedded in a dielectric film
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FIGURE 5.9 A traveling wave of potential is applied at x = -d. A lossy dielectric
layer of thickness d, permittivity e, and conductivity s prevents charged dust from
penetrating into the region x < 0. The x = 0 surface has reduced potential magnitude
(V1< V0) and a lagging phase b to the driving x = -d potential
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FIGURE 5.10 Cross-section of an EDS made of a flexible polyethylene terephthalate
(PET) film of 500 mm thickness on which transparent ITO electrodes of rectangular
cross-section (width 10 mm, height 10 mm) are deposited with an inter-electrode
spacing of 1000 mm. The electrodes are embedded within a PU film coating with a
film thickness of 50 mm. The thickness of the electrodes is varied from 10 to 100 mm
and the inter-electrode spacing from 100 mm to 1000 mm for optimization
of EDS operation
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FIGURE 5.11 The electric field has been modeled for three electrode configurations.
The top section shows electrodes with relatively large dimensions and large interelectrode spacing. The spatial distribution of the divergent electric field intensity is
non-uniform. As the electrode dimensions and the inter-electrode spacing are
reduced, more uniform field intensity distributions are achieved (middle and bottom
sections)
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FIGURE 5.12 A charged (+q) particle of diameter 2 mm, located at A, is subjected to
an AC electrical field E0sin(wt) applied between the adjacent electrodes as shown.
The frequency of the electric field is 4 Hz
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FIGURE 5.13 An uncharged dielectric particle, deposited on the surface of a
dielectric film, is experiencing a dielectrophoretic force because of the induced
dipole moment on the particle by the applied non-uniform electric field
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FIGURE 5.14 Induction charging of conducting and semi-conducting particles
deposited on a dielectric screen with embedded electrodes. e1 and e2 are the relative
dielectric constants of the screen and the particle, respectively
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FIGURE 5.15 Three-phase voltages (a) in sinusoidal waveforms and (b) in square
waveforms
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FIGURE 5.15 (continued) Three phase square wave forms
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FIGURE 5.16 Block diagram of an EDS power supply
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FIGURE 5.17 Schematic diagram of an experimental EDS power supply based on
1.2-kV MOSFETs
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FIGURE 5.18 MOSFET-based EDS power supply (a) in a housing and (b) circuits in
a PCB
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FIGURE 5.19 Linear-amplifier-based EDS power supply (a) in a system test setup
and (b) block diagram
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FIGURE 5.20 Power vs. voltage curves for a three-phase PCB EDS with 1-mm
electrode spacing
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FIGURE 5.21 Power curves for a three-phase ITO electrode-EDS with 1-mm
electrode spacing
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FIGURE 5.22 A 3D view of the test chamber for studying the performance of the
electrodynamic screens. The environmental conditions can be adjusted (temperature
up to 50 degrees and relative humidity (RH) up to 80% can be achieved) inside the
chamber. The solar panels can be tilted at different angles
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FIGURE 5.23 An experimental setup for testing transparent electrodynamic screens
against mass loading of test dust under normal atmospheric conditions
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FIGURE 5.24 Experimental arrangement for testing the EDS under Martian
atmospheric conditions (0.5 to 1.0 kPa pressure, CO2 atmosphere) to determine the
dust removal efficiency as a function of dust loading. For each experiment, the total
power requirements for removal of the dust layer were measured as functions of
applied voltage pulses and the frequency of operation
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FIGURE 5.25 Maximum power point operation of a solar panel
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FIGURE 5.26 Application of an integrated circuit (IC) to control the output voltage
for MPP operation
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FIGURE 5.27 Voltage converter for MPP operation
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FIGURE 5.28 Size distribution of Mars dust simulant measured by an ESPART
analyzer
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FIGURE 5.29 Charge distribution of Mars dust simulant as measured by an ESPART
analyzer.
The particles were bipolarly charged as shown in the figure
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FIGURE 5.30 The net charge-to-mass ratio in mC/g of Mars dust simulant particles
measured using an ESPART analyzer varied depending on the process conditions. The
particles became charged primarily during the dispersion process
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FIGURE 5.31 Dust removal efficiency of a three-phase EDS operating at 750, 1000,
and 1250 volts (electrode spacing = 1.27 mm, electrode width = 0.127 mm, f = 4 Hz,
cleaning operation time = 60 s)
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FIGURE 5.32 Dust removal efficiency of a three-phase EDS with and without charge
neutralizer (electrode spacing = 1.27 mm, electrode width = 0.127 mm, peak-to-peak
voltage = 1250 V, f = 4 Hz, run time = 60 s, count median (aerodynamic) diameter of
the dust particles = 3.66 mm, d10 = 1.22 mm, d50 = 9.06 mm, d90 = 38.45 mm)
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