연료전지에서 전류분포를 측정할 수 있는 시스템에 대한
안내입니다.
모델은 Current Scan High resolution (전류분포측정) 및 Current Scan Linear(전류분포 및 온도 분포 측정)
두가지입니다.
User
interface CurrentVIEW
The user interface
CurrentVIEW is easy to use and
self-explanatory. It allows:
+ single and continuous
measurements
+ visualization in 2D,
3D and as values
+ saving data as text
files in spreadsheet format
+ saving data as
pictures in jpg format
+ saving and reviewing
of data streams.
Also a dll can be
introduced into an existing environment.
Current Scan
Lin
Current density
distribution and tempera-ture distribution measurement in fuel cell
stacks.
+ detailed
analysis of flow fields
+ detailed
analysis of materials
+
optimization of fuel cells
+ fault
diagnostics in fuel cells
+ resolution
of about 7 x 7 mm
+ current
range up to 2.5 A/cm²
+ temperature
range up to 180°C
+ standard
devices are available
+ special
designs on request
With the current scan lin, the current density
distribution can be measured with a high resolution and it offers a linear
complexity. So it is also applicable in large fuel cells. It is connected via
USB to any computer and easy to use.
In a fuel cell the
locale conditions differ which leads to an inhomogeneous mass conversion
re-sulting in an inhomogeneous current production. One of the keys to a deeper
understanding of PEM fuel cells, DMFC and other electrochemical cells is the
measurement of the current density distribu-tion. In large fuel cells this is
important for a save and reliable operation as well as a high lifetime. Up to
now the high complexity was a major problem.
Application
The device of type
?current scan lin“ shown on the first
page has a resolution of 17 x 19 meas-urement cells and an active area of
150cm². It will be placed between the two half’s of a bipolar plate at an
arbitrary place in the stack. The pictures be-low show a typical current
distribution and a tem-perature distribution.
Measurement Principle
The permeability of a
magnetic material is depend-ing on the magnetization and the temperature. The
current Im, which has to be measured, flows through the coil L1 and causes a
magnetization of the magnetic matrial (dashed line). An alter-nating current
i(t), feed into L2, induces a voltage u(t) into the coil L3. This voltage
depends upon the permeability of the magnetic material (dashed line). So it
depends upon the current Im.
The single measurement
cells are conducted in series in rows and columns. This is shown in the
following picture for example at 3 x 3 measurement cells.
The alter-nating
cur-rents i1(t) to in(t) will be feed con-secutively into the matrix to activate
the rows 1 to n. At the col-umns the voltages u1(t) to un(t) will be acquired as
measurement signals. The measurement cells which are not activated by an
alternating current deliver nothing to the measure-ment signal. In general n²
measurement points can be reached with 2 n wire pairs. So the complexity for
connection wires, control and evaluation elec-tronics is linear! This way
measurement devices for arbitrary large fuel cells can be build easily.
Available
standard devices
The picture shows the
standard devices Test25,
Test50 and Test100
complete with 25cm², 50cm² and 100cm² single cell fuel cell and resistors to
heat up the fuel cells.
Also available is the
shown universal design. Out-side the active area with measurement cells and a
restricted area for the conductor paths, arbitrary holes may be drilled.
Different electronics (pic-
ture beside) which are
able to drive up to 48 rows and 48 columns are available. They also differ in
the number of inde-pendent input channels, influencing the speed.
Custom made
device
The above picture
shows custom made sensor plate with active area 800cm² and 46 x 36 measurement
cells. Nearly any design is possible. The minimal size of the measurement cells
is 7 x 7mm. The maximal size is restricted by the current they have to meas-ure
and should not be much larger.
Current Scan High Res
Current density
distribution measurement in fuel cells with high resolution.
+ detailed
analysis of flow fields
+ detailed
analysis of materials
+
optimization of fuel cells
+ fault
diagnostics in fuel cells
+ resolution
of about 1 x 1 mm
+ current
range up to 2A/cm²
+ standard
devices are available
+ special
designs on request
With the current scan high res, the cur-rent density
distribution can be measured with a very high resolution. It is connected via
USB to any computer and easy to use.
In a fuel cell the
locale conditions differ which leads to an inhomogeneous mass conversion
re-sulting in an inhomogeneous current production. One of the keys to a deeper
understanding of PEM fuel cells, DMFC and other electrochemical cells is the
measurement of the current density distribu-tion. This is important for a save
and reliable op-eration as well as a high lifetime.
Application
The device of type
?current scan high
res“
shown on the first page has a resolution of 32 x 36 meas-urement cells and an
active area of 25cm². The picture below shows a sectional view of the setup.
The gas diffusion
layer will be placed directly on the segments. The channels of the flow field
are milled between the segments. The device is usable as anode or cathode of a
single cell.
The picture below
shows a typical current distribution.
Measurement Principle
The devices of this
series use a segmented electrode with segments of about 1mm² connected to single
electronic loads trough a multilayered printed circuit board.
An electronic load,
connected to a segment, is shown in the following picture.
The electronic loads
are realized with operational amplifiers which work as current source or sink.
So the device can be used on the anode or optionally on the cathode side. The
voltage after the resistor R is feed back to the operational amplifier OP. So
the voltage Uout at the segment is held constant at the voltage of the input
Uin. The voltage Um is measured and the current which flows out of the segment
or into the segment is calculated with help of the formula
Many of these
electronic loads are connected with a multiplexer which switches the voltages Um
to an Analog-to-Digital converter. The inputs are connected together and the
voltage Uin is provided by an Digital-to-Analog converter. This is shown in the
following picture.
The size of the device
is limited, because the complexity grows quadratically with the size or
resolution. For large fuel cells there is another principle available which is
realized in the devices of the series “current scan lin”.
Available
standard device
The available standard
device is designed for a 25cm² ECF 25 single cell fuel cell from Electro Chem.
It has 32 x 36 segments of 1.47 x 1.64mm on a base plate. 18 boards with 64
electronic loads and a data-acquisition system with USB interface are pluged
into the base plate. The power supply is in a 19” housing.
Custom made devices
Nearly any custom made
design is possible. The minimal size of the measurement cells is 1 x 1mm. The
maximal size is restricted by the current the operational amplifiers are able to
deliver. But be-cause of the quadratic complexity the devices of the series
”current scan high
res” are
restricted to small devices. For large fuel cells or fuel cell stacks please ask
for a device of the series “current scan lin”.
Specification
www.electrochemistry.co.kr item update
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