SUPPLIER INTERVIEW: MIBA
2
2. Miba’s FLEXcooler
“Thermal management in
electric car batteries is critical
to determine range and longevity”
Stefan Gaigg, business unit leader, battery, Miba
technology is a battery
cooling system that is
adaptable to a broad
range of geometries
www.electrichybridvehicletechnology.com // January 2020 // 139
of this heat exchanger,” says Gaigg, “is that
the thermal contact is formed even without
thermal interface materials, which must be
used with conventional heat exchangers.”
The fl exible heat exchanger is electrically
non-conductive, with a dielectric strength
above 5kV, which provides an additional level
of electrical safety.
Flexibility of materials, he suggests, enables
additional benefi ts such as compensation of
manufacturing tolerances and enabling
cooling in gaps as small as 1mm. Larger gaps,
up to 6mm, are also possible.
The fl exible heat exchanger is highly
durable, able to withstand 250,000 pressure
pulses from 0,1 to 2.5 bar without any damage.
“This is far above the operating pressure,”
explains Gaigg. “Already, pressures of 0.5 bar
press the heat exchanger tightly against the
housing of battery cells. The resulting tight
thermal contact between heat exchanger
and battery cells with typical heat transfer
coe cients of ~1000W/m2K
provides e cient cooling,
demonstrated for example by the
uniform temperature of the
chilled macro cell that is built of
cylindrical cells.”
The fl exible heat exchanger can
be operated at temperatures
ranging from -30°C to +60°C (-22°F
to 140°F) It can also be custom fi t to almost
any battery design, ranging from prismatic
to pouch and cylindrical cells and format.
Sizes of 2,000mm x 1,400mm are possible.
Hausjell reveals that work is already
underway on the company’s next generation
of fl exible heat exchangers: iFLEXcooler
will be intelligent and fl exible, able to
sense the temperature at the
interface between the heat
exchanger and battery. “The heat
exchanger can even be equipped
with heating,” he explains. “An
advantage of this is that heat is generated
right where it is needed – at the interface
between the battery cell and heat exchanger at
powers of several 1,000W/m2.” This, he says,
reduces energy loss
due to the heating of
the coolant or coolant
pump, which provides
e cient thermal management of the
battery after a cold night.
Looking ahead to the future
The recyclability of battery packs will become
even more important. Despite the tight
thermal contact of the fl exible heat exchanger,
the contact is mechanically reversible, enabling
easy disassembly of the heat exchanger and
battery. “Saving the thermal interface
materials will reduce the product’s
environmental impact and it will also reduce
the number of resources used.”
“Together with Voltlabor, we have built a
battery module that demonstrates all these
advantages. It is highly versatile due to the
modular macro cell, and is suitable for diff erent
module and pack sizes while being optimized
for automated assembly.”
A further key issue in the future
will be increasing power density.
The FLEXcooler will contribute
to this twofold. First, by reducing
the space required for cooling,
and second, by providing a higher
e ciency in cooling, which may
be needed if power density and
any resulting power density loss increase. “The
trend to fully automated assembly processes
will continue,” he adds, “and we will support
our customers in this with our products
that are optimized for automated
assembly processes.”
Also important is monitoring the
state of the battery, in preserving capacity
and counteracting damage to it. “With the
integration of sensors in the heat exchanger,
such monitoring will become possible.” Time
to market, Gaigg says, will continue to get
shorter in what he calls “the global exchange
of ideas.” And he concludes, “We will continue
to prepare for this with highly adaptable
production, suitable for diff erent formats and
sizes of batteries and heat exchangers.”
3
3. Prismatic and cylindrical
battery cells can be cooled
to prevent power loss
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