Solid-State Thermal Management and Energy Harvesting
FREE FROST HEAT EXCAHANGER
1. FROST FREE HEAT EXCHANGER FOR
CRYOGENIC AUTOMOTIVE PROPULSION
PRESENTED BY
NITESH CHOWDHURY
6th
SEM AUTO.
ROLL NO 18
2. The Air Resources Board enacted the Low Emission
Vehicle(LEV).
Zero Emission Vehicle (ZEV).
Pollution can cause aching lungs, wheezing, coughing
and head aches.
Serious health problems.
Children are at particular risk.
3. Currently, battery powered electric vehicle
is the only commercially available
technology that meet ZEV standards.
Slow recharge and high initial cost.
The energy storage medium may well be
liquid nitrogen.
Frost free heat exchanger performance.
4. The cryogenic automobile is a ZEV.
Operates on the thermo dynamic potential
between the ambient atmosphere and a
reservoir of liquid nitrogen.
5. The liquid nitrogen is drawn from a tank
,pumped up to system pressure.
Vaporized and superheated in a heat exchange
system.
High pressure and ambient temperature gas-
system does work.
The spent low pressure gas is exhausted back
to atmosphere.
6.
7. As nitrogen gas is the only emission ,the
cryogenic automobile, it meets ZEV guide
lines.
Frost free liquid nitrogen heat exchange
system can be very advantageous.
8. Operate in a variety of conditions and is
structurally robust-not being hampered by the
build up of frost.
Dealing with frost formation fall into two
categories:
1) PASSIVE CONTROL.
2) ACTIVE CONTROL.
9. Either preventing frost formation, or over
sizing the heat exchanger such that frost
build up is unimportant.
11. In general ,less flexible in dealing with off-
design operation.
12. Active control of frost formation entails allowing
frost to accrete and then removing it
mechanically.
13. More operationally robust.
Performance of an actively controlled heat
exchanger is much less dependent on the
ambient or operational conditions since these
systems can be responsive to different loading
conditions.
14. Power consumption.
Poor long term reliability.
The operating environment can be a hazardous
Driving conditions.
Rigorous safety.
Comfort.
15. To prevent frost build upon sub ambient
heat exchangers, the exterior surfaces
must be kept above the freezing point of
water.
The principle is the same as for multi fluid
heat exchange systems, where heat Is
transferred from source to sink via a
number of media operating in series.
16. The choice of
passes was based
on two practical
condition.
Passive heat
exchangers are
more tightly coupled
to environmental
and
operating
conditions.
17. Achieve a very compact unit.
A heat exchanger has been developed
which uses rotating brushes for active
frost control.
18. The cryogenic automobile is a potential contender in the
ZEV market , provided certain key technologies are
demonstrated. One of these technologies is the
development of an all weather heat exchange system.
A heat exchanger that works well in a variety of
operating conditions, is structurally robust, and is not
hampered by the build up of frost is a necessary
technology for the cryogenic automobile.
Experiments are yet to be conducted to determine the
actual performance.
Until road test experiments are conducted, the actual
thermal performance will not be known with enough
accuracy to support an overall recommendation for the
final heat exchange system design.