In 1997, the University of North Texas (UNT ) and University of Washington (UW)
independently developed liquid nitrogen powered vehicles in which the
propulsion systems in these vehicles are cryogenic heat engines in which a
cryogenic substance is used as a heat sink for heat engine.
Cryogenic:
Cryogenic can be defined as the branch of
the physics that deals with the production of and study of effects and very low
temperature.
Cryogenic
Engineering:
It is mainly
concerned with temperatures found in range of –150oC to absolute
zero (-273.15oC).
Various
Cryogenic Fluids:
q Liquid Helium
q Liquid Nitrogen
Cryogenic
Heat Engine:
It is a engine which uses very cold
substances to produce useful energy. A unique feature of an cryogenic heat
engine is that it operates in an environment at the peak temperature of the
power cycle, thus, there is always some heat input to the working fluid during
the expansion process.
Liquid Nitrogen :
Liquid Nitrogen is the cheapest, widely
produced and most common cryogenic liquid.
It is mass produced in air liquefaction plants. The liquefaction process is very simple in it
normal, atmospheric air is passed through a dust precipitator and pre-cooled
using conventional refrigeration techniques. It is then compressed inside large
turbo pumps to about 100 atmospheres.
Once the air has reached 100 atmospheres and has been cooled to room
temperature it is allowed to expand rapidly through a nozzle into an insulted
chamber. By running several cycles the
temperate of the chamber reaches low enough temperatures the air entering it
starts to liquefy. Liquid nitrogen is
removed form the chamber by fractional distillation and is stored inside well-insulated
Dewar flasks.
How does the Nitrogen Powered car work?
Heat from the atmosphere vaporizes liquid
nitrogen under pressure and produces compressed nitrogen gas. This compressed gas runs a pneumatic
(compressed gas drive) motor with nitrogen gas as the exhaust.
Main Components of the Engine:
q A pressurized tank to store liquid
nitrogen
q A heat exchager that heats (using
atmospheric heat) liquid nitrogen to form nitrogen gas, then heats gas under
pressure to near atmospheric temperature.
q A pneumatic motor (along with a Volkswagen
transmission) that runs the car.
Principle of Operation :
The principle of running the LN2000Car is
like that of steam engine, except there is no combustion involved. Instead liquid nitrogen at –320oF
(-196oC) is pressurized and then vaporized in a heat ex-changer by
ambient temperature of the surroundings air.
This heat ex-changer is like the radiator of a car but instead of using
air to cool water, it uses air to heat and boil liquid nitrogen. The resulting high pressure nitrogen gas is
fed to an engine that operates like a reciprocating steam engine, converting
pressure to mechanical power. The only exhaust is nitrogen, which is major
constituent of our atmosphere.
Analysis of CooLN2 Car Performance:
A single-cylinder reciprocating How does the Nitrogen Powered car work?
Heat from the atmosphere vaporizes liquid
nitrogen under pressure and produces compressed nitrogen gas. This compressed gas runs a pneumatic
(compressed gas drive) motor with nitrogen gas as the exhaust.
Main Components of the Engine:
q A pressurized tank to store liquid
nitrogen
q A heat exchager that heats (using
atmospheric heat) liquid nitrogen to form nitrogen gas, then heats gas under
pressure to near atmospheric temperature.
q A pneumatic motor (along with a Volkswagen
transmission) that runs the car.
Principle of Operation :
The principle of running the LN2000Car is
like that of steam engine, except there is no combustion involved. Instead liquid nitrogen at –320oF
(-196oC) is pressurized and then vaporized in a heat ex-changer by
ambient temperature of the surroundings air.
This heat ex-changer is like the radiator of a car but instead of using
air to cool water, it uses air to heat and boil liquid nitrogen. The resulting high pressure nitrogen gas is
fed to an engine that operates like a reciprocating steam engine, converting
pressure to mechanical power. The only exhaust is nitrogen, which is major
constituent of our atmosphere.
Analysis of CooLN2 Car Performance:
A single-cylinder reciprocating ex-pander that runs on compressed nitrogen gas with the exhaust gas released into the
atmosphere was considered. When compressed gas flowed into the ex-panders cylinder, isobaric work was done on the moving piston by the gas.
The
net isobaric expansion work done during a single cycle is gauge pressure of the
gas multiplied by the volume of the gas
that flows into the cylinder.
The isobaric specific energy is Wi
= (Ph-Pi)V= Ph(1-P-1)V
Ph-Pi is the
difference in absolute pressure between inlet and exhaust gas.
If Pi is atmospheric pressure,
Ph-Pi is the gauge pressure of compressed gas.
V is the volume occupied by the
compressed gas per unit mass of gas.
P = Ph / Pi is
inlet to exhaust pressure ratio.
The isobaric specific energy is Wi
= RTh (1-P-1) /A.
Here Th refers to the
temperature of the high pressure inlet gas.
The
COOLN2Car which a converted 1973 Volkswagen and runs on liquid nitrogen is an
illustrative to the use of isobaric expansion equation. that runs on compressed nitrogen gas with the exhaust gas released into the
atmosphere was considered. When compressed gas flowed into the expanders
cylinder, isobaric work was done on the moving piston by the gas.
The
net isobaric expansion work done during a single cycle is gauge pressure of the
gas multiplied by the volume of the gas
that flows into the cylinder.
The isobaric specific energy is Wi
= (Ph-Pi)V= Ph(1-P-1)V
Ph-Pi is the
difference in absolute pressure between inlet and exhaust gas.
If Pi is atmospheric pressure,
Ph-Pi is the gauge pressure of compressed gas.
V is the volume occupied by the
compressed gas per unit mass of gas.
P = Ph / Pi is
inlet to exhaust pressure ratio.
The isobaric specific energy is Wi
= RTh (1-P-1) /A.
Here Th refers to the
temperature of the high pressure inlet gas.
The
COOLN2Car which a converted 1973 Volkswagen and runs on liquid nitrogen is an
illustrative to the use of isobaric expansion equation.
