The document discusses cryogenics and cryogenic heat engines. It describes how a cryocar works using liquid nitrogen as fuel. Liquid nitrogen is pressurized and vaporized in a heat exchanger, producing pressurized nitrogen gas that drives the engine. While this eliminates vehicle emissions, liquefying nitrogen requires energy and the technology has limitations regarding speed, leakage hazards, and lack of refueling infrastructure. More research is still needed to address safety and commercialization.

1. Roll No. 73
Batch – M5
22 November 2022
1

2. CRYOGENICS
 Cryo - means cold
 Genics - means science.
 The branches of physics and engineering that
involve the study of very low temperatures, how to
produce them, and how materials behave at those
temperatures.
22 November 2022
2

3. WHAT IS A CRYOCAR ?
 It is a liquid nitrogen powered vehicle.
 Propulsion systems are cryogenic heat engines in
which a cryogenic substance is used as a heat sink.
22 November 2022
3

4. 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.
 Cryoengine works on Rankin Cycle.
22 November 2022
4

5. 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.
 Normal, atmospheric air is passed through dust
precipitator and pre-cooled.
22 November 2022
5

6. Atmospheric
Air passes
Fractional
Distillation
Dust
Precipitator
Inter cooler
Nozzle
LN
2
Insulated
chamber
Expansion
Turbo
pumps
Dewar Flask
Block diagram 22 November 2022
6

7. • It is then compressed inside large turbo pumps to
about 100 atmospheres.
• 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 .
22 November 2022
7

8. Main Components of the Engine:
 A pressurized tank 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.
22 November 2022
8

9. Components Of Operation
22 November 2022
9

10. 22 November 2022
10

11. Principle of Operation:
 LN2 at –320 °F (-196 °C) 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 psi.
22 November 2022
11

12. Principle of Operation
22 November 2022
12

13. •The pressurised N2 gas drives the motor.
•The only exhaust is nitrogen, which is major
constituent of our atmosphere.
•Energy+N2(l)-->N2(g)
hence, there is no pollution produced by running
this car.
22 November 2022
13

14. POWER CYCLE
22 November 2022
14

15. ADVANTAGES OVER ELECTRIC CARS:
 Much like electrical vehicles, liquid nitrogen vehicles
would ultimately be powered through the electrical grid.
Which makes it easier to focus on reducing pollution from
one source, as opposed to the millions of vehicles on the
road.
 Transportation of the fuel would not be required due to
drawing power off the electrical grid. This presents
significant cost benefits. Pollution created during fuel
transportation would be eliminated.
 Lower maintenance costs
22 November 2022
15

16. Conti……
 Liquid nitrogen tanks can be disposed of or
recycled with less pollution than batteries.
 Liquid nitrogen vehicles are unconstrained by the
degradation problems associated with current
battery systems.
 The tank may be able to be refilled more often and
in less time than batteries can be recharged, with
re-fueling rates comparable to liquid fuels.
22 November 2022
16

17. DRAWBACKS:
 The N2 passing through the tubes of the heat exchanger is so cold that
the moisture in the surrounding air would condense on the outside of
the tubes, obstructing the air flow.
 Then there's the safety issue. Should a nitrogen car be kept in a poorly
ventilated space and, if the Nitrogen leaks off, it could prove fatal.
 Turning N2 gas into a liquid requires a lot of energy. So while cryogenic
cars have zero emissions, they rely on energy produced at emission
generating power plants.
 The principal disadvantage is the inefficient use of primary energy.
Energy is used to liquefy nitrogen, which in turn provides the energy to
run the motor. Any conversion of energy results losses. For liquid
nitrogen cars, electrical energy is lost during the liquefaction process of
nitrogen.
 Liquid nitrogen is not yet available in public refueling stations.
22 November 2022
17

18. Efficiency:
 The LN2 car can travel 15 miles on a full (48
gallon) tank of liquid nitrogen going 20 MPH.
 Its maximum speed is over 35 MPH.
22 November 2022
18

19. Why not commercialized?
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.
 Technology has certain limitations such speed,
leakage hazard, generating liquid nitrogen etc.
22 November 2022
19

20. 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.
22 November 2022
20

21. References:
 Research paper on “Liquid Nitrogen as a Non-
Polluting Vehicle Fuel” by Mitty c. Plummer, Carlos
A. Ordonez and Richard F. Reidy, University of North
Texas.
 The University of Washington’s Liquid Nitrogen
Propelled Automobile
 Popular Science, 1998.
 Wikipedia
 Nhts.com(National Highway Traffic Security)
22 November 2022
21

22. 22 November 2022
22

23. ?
22 November 2022
23