This document describes a cryocar, which is a vehicle that uses liquid nitrogen as a working fluid in a cryogenic heat engine. It discusses the history of cryocars developed in 1997 using liquid nitrogen, and describes the main components of a cryocar's engine such as the Dewar flask, heat exchanger, and pressurant bottles. The working principle is explained as liquid nitrogen being pressurized and vaporized through heat exchange, then expanding to drive an air motor. Advantages include being lighter weight and more eco-friendly, while disadvantages include high energy requirements and safety issues with nitrogen leakage. More research is still needed to address safety and commercialization.

1. DR. SAU. KAMALTAI GAWAI INSTITUTE OF
ENGINEERING & TECHNOLOGY, DARAPUR.
Department of mechanical engineering
Presentation on-
CRYOCAR
Presented By-
Akshay V. Tayde

2. What is Cryocar ?
• It is a vehicle which uses Cryogenic
fluid as a working fluid.
• Propulsion system is a cryogenic heat
engine in which a cryogenic substance
is used as a heat sink.

3. History
• In 1997, the liquid nitrogen powered vehicles was
independently developed by University of North Texas
(UNT) and University of Washington (UW).
• The propulsion systems in these vehicles were
cryogenic heat engines in which a cryogenic substance
is used as a heat sink for heat engine.

4. • It was a converted
1984 Grumman-Olson
Kubvan mail delivery
van.
•The vehicle (car) was
named as LN2000.

5. Why Liquid Nitrogen?
• Liquid nitrogen is the liquefied form of the
element “nitrogen” that is commercially produced
by fractional distillation of liquid air.

6. Cryogenic Heat Engine
• It is a engine which uses very cold
substances to produce useful energy.
• There is always some heat input to the
working fluid during the expansion
process.

7. Liquid Nitrogen (LN2)
• Liquid Nitrogen is the cheapest, widely
produced and most common cryogen.
• It is mass produced in air liquefaction plants
• The liquefaction process is very simple.

8. Dust
Precipitator
Inter
Cooler
Nozzle
Insulated
Chamber
LN2
Turbo
Pumps
Air Inlet
Fractional
distillation
Dewar Flask
Formation Of LN2:
Expansion

9. • Normal, atmospheric air is passed through dust
precipitator and pre-cooled.
It is then compressed inside large turbo pumps to about 100
atmospheres (10.13 MPa).
• Once the air has been cooled to room temperature it is
allowed to expand rapidly through a nozzle into an insulated
chamber.
• By running several cycles the temperature of the chamber
becomes low enough. The air entering it starts to liquefy.
• Liquid nitrogen is removed from the chamber by fractional
distillation and is stored inside well-insulated Dewar flasks .

10. Main Components of the Engine:
Dewar Flask Heat Exchanger
Pressurant Bottles
Air Motor
Economizer
Exhaust

11.  A pressurized tank (24 gallon) to store liquid nitrogen.
 Pressurant bottles of N2 gas substitute for a pump. The gas
pushes the liquid nitrogen out of the Dewar that serves as
a fuel tank.
 A primary heat exchanger that heats (using atmospheric
heat) LN2 to form N2 gas, then heats gas under pressure to
near atmospheric temperature.
 An Expander to provide work to the drive shaft of the
vehicle.
 An economizer or a secondary heat exchanger, which
preheats the liquid N2 coming out from the pressurized
tank taking heat from the exhaust.

13.  LN2 at –320oF (-196oC) is pressurized and then
vaporized in a heat exchanger by ambient temperature
of the surrounding air.
 This heat exchanger is like the radiator of a car but
instead of using air to cool water, it uses air to heat and
boil liquid nitrogen.
• Liquid N2 passing through the primary heat exchanger
quickly reaches its boiling point.
• The N2 expands to a gas with a pressure of 150 KPa.
Working Principle:

14. Working Principle:
 The pressurized N2 gas drives the
motor.
 The only exhaust is nitrogen,
which is major constituent of our
atmosphere.
 Heat Energy + N2(l) → N2(g) +
Work Done
Hence, there is no pollution
produced by running this car.
Liquid nitrogen energy conversion system

15. Theory Behind Cryocar (Rankine Cycle) :

16. Process 1-2: The working fluid is pumped from low to high
pressure. As the fluid is a liquid at this stage, the pump
requires little input energy.
Process 2-3: The high pressure liquid enters a boiler where
it is heated at constant pressure by an external heat source to
become a dry saturated vapour.
Process 3-4: The dry saturated vapour expands through
a turbine, generating power. This decreases the temperature
and pressure of the vapour, and some condensation may
occur.
Process 4-1: The wet vapour then enters a condenser where
it is condensed at a constant pressure to become a saturated
liquid.

17. Efficiency:
• The first LN2 car could travel 79 miles (127.58 km) on a
full 24 gallon (90 liter) tank of liquid nitrogen going 32
Kmph.
• Its maximum speed was over 56 Kmph.
After further Researches, the Efficiency has improved as
follows:
• Power : 78KW or 104.5bhp @ 97Kmph.
• 400 Liters (106 gallon) gives a mileage of 560Km and
weighs 280Kg.
• Operating Cost is around 2.4 cents per Km( Re 1 per Km).

18. Advantages:
• Car is much lighter in
weight.
• Refilling its tank takes only
15 minutes.
• Eco-friendly.
• Lithium-ion and lead-acid
batteries and source of
electricity.

19. • Requires a lot of energy.
• Gas is so cold that the
moisture in the surrounding air
would condense on the outside
of the tubes.
• Safety issue.
• Leakage of N2 leads to prove
fatal.
Disadvantages:

20. • Even though the technology is 10 to 12
years old, still it has not come to the
market for two reasons:
• Safety issues have not been sorted out
as yet.
• Lack of funds for research.
Why not commercialized?

21. Probable Solutions:
• A tube within a tube design.
• N2 passes back and forth inside a set of three nested
tubes.
• By the time it reaches the outermost tubes, the N2 is
warm enough that the exterior wall of the tube
remains above the freezing point of water.

22. Conclusion:
• In a real sense, the more such vehicles are used, the
cleaner the air will become.
• In addition to the environmental impact of these
vehicles, refueling using current technology can take
only a few minutes, which is very similar to current
gas refueling times.
• Extra research work is needed to utilize the most of
the available energy

23. References:
• “LN2000”, University of Washington Research Team,
Sept. 18, 2007.
• “Liquid Nitrogen”, Wikipedia Online Encyclopedia.
• Brent S. Mattox. "Investigative Report on Chemistry
301A Cylinder Explosion“. Texas A&M University.
• Philadelphia: ASTM International Subcommittee G-
4.05. Werley, Barry L. (Edtr.) (1991). "Fire Hazards in
Oxygen Systems". ASTM Technical Professional
training.

24. Thank You