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.

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.

10.  Mechanical simplicity.
 Reliability.

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.