FREE FROST HEAT EXCAHANGER Presentation Slide.ppt

7/27/2019 FREE FROST HEAT EXCAHANGER Presentation Slide.ppt

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FROST FREE HEAT EXCHANGER FORCRYOGENIC AUTOMOTIVE PROPULSION

PRESENTED BY

M.SATHISHKUMAR

II M.ETHERMAL


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The California 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 is at particular risk.


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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.


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The cryogenic automobile is a ZEV.

Operates on the thermo dynamic potential

between the ambient atmosphere and a

reservoir of liquid nitrogen.


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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-

systems motive work.

The spent low pressure gas is exhausted back toatmosphere.


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As nitrogen gas is the only emission ,thecryogenic automobile meets Californias ZEV

guide lines.

Frost free liquid nitrogen heat exchange system.


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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 twocategories:

1) PASSIVE CONTROL.

2) ACTIVE CONTROL.


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Either preventing frost formation, or over sizing

the heat exchanger such that frost build up is

unimportant.


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Mechanical simplicity.

Reliability.


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In general ,less flexible in dealing with off-

design operation.


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Active control of frost formation entails allowing

frost to accrete and then removing it

mechanically.


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More operationally robust.

Performance of an actively controlled heat

exchanger is much less dependent on the

ambient or operational conditions since thesesystems can be responsive to different loading

conditions.


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Power consumption.

Poor long term reliability.


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The operating environment can be a demanding

one.

Weather conditions.

Driving conditions. Rigorous safety.

Comfort.


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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.


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The choice of passes

was based on twopractical condition.

Passive heat

exchangers are moretightly coupled to

environmental and

operating conditions.


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Achieve a very compact unit.

A heat exchanger has been developed which uses

rotating brushes for active frost control.


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The cryogenic automobile is a potential contender in

the ZEV market , provided certain key technologiesare 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 isnot 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 thermalperformance will not be known with enough

accuracy to support an overall recommendation for

the final heat exchange system design.


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FREE FROST HEAT EXCAHANGER Presentation Slide.ppt