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. A Liquid Nitrogen Car
There are approximately 247 million vehicles in the U.S. today and approximately 97% of those vehicles are gasoline or diesel powered The current average fuel efficiency of automobiles in the U.S. is 20.2 miles per gallon nearly 50% lower than on road fuel economy in other industrialized nations .This presents a twofold challenge . First, fossil fuel supplies are limited. Some estimates indicate that the world could see a peak in its total oil production mandated by resource availability and economic and political factors as soon as 2012.After such a peak, fossil fuel production will decrease . Second, gasoline powered vehicles are extremely dirty. Burning one gallon of gasoline emits 19.4 pounds of carbon dioxide along with a host of other pollutants In response to this obvious need for a shift away from fossil fuel powered vehicles, we propose to explore the use of liquid nitrogen as a combustion-free clean alternative vehicle fuel. The use of liquid nitrogen as such a fuel for automobiles has many possibly far-reaching benefits. Several analyses have shown that the specific energy achievable with cryogenic heat engines using liquid nitrogen as the working fluid are comparable to current battery technologies. 1,2 Since the source of liquid nitrogen is air (78% of air is nitrogen), liquid nitrogen is readily available at a low cost. In a liquid nitrogen cryogenic heat engine, ambient heat from the atmosphere is used as a heat source to cause liquid nitrogen to phase change from a liquid to a gas. Subsequent heating of the gas by heat from the atmosphere provides rapid expansion to run an expander. The exhaust gas, nitrogen gas, is released into the atmosphere. It should be noted that air is composed of 78% nitrogen, and so the exhaust gas of a liquid nitrogen engine is simply a component of air. A cryogenic heat engine running on liquid nitrogen is an environmentally clean, combustion-free engine, which could be used for zero emission vehicles
2. CRYOGENIC AND ITS DEVELOPMENT
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.
The upper limit of cryogenic temperatures has not been agreed on, but the National Institute of Standards and Technology has suggested that the term cryogenics be applied to all temperatures below -150°C (-238°F or 123° above absolute zero on the Kelvin scale). Some scientists regard the normal boiling point of oxygen (-183°C or -297°F), as the upper limit. Cryogenic temperatures are achieved either by the rapid evaporation of volatile liquids or by the expansion of gases confined initially at pressures of 150 to 200 atmospheres. The expansion may be simple, that is, through a valve to a region of lower pressure, or it may occur in the cylinder of a reciprocating engine, with the gas driving the piston of the engine. The second method is more efficient but is also more difficult to apply. Pioneering work in low-temperature physics by the British chemists Sir Humphrey Davy and Michael Faraday, between 1823 and 1845, prepared the way for the development of cryogenics. Davy and Faraday generated gases by heating an appropriate mixture at one end of a sealed tube shaped like an inverted V. The other end was chilled in a salt-ice mixture.. The combination of reduced temperature and increased pressure caused the evolved gas to liquefy. When the tube was opened, the liquid evaporated rapidly and cooled to its normal boiling point. By evaporating solid carbon dioxide mixed with other, at low pressure, Faraday finally succeeded in reaching a temperature of about 163 K (about -110°C/-166°F).If a gas initially at a moderate temperature is expanded through a valve, its temperature increases. But if its initial temperature is below the inversion temperature, the expansion will cause a temperature reduction as the result of what is called the Joule-Thomson effect. The inversion temperatures of hydrogen and helium, two primary cryogenic gases, are extremely low, and to achieve a temperature reduction through expansion, these gases must first be pre-cooled below their inversion temperatures.
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 from the chamber by fractional distillation and is stored inside well-insulated Dewar flasks.
A liquid nitrogen vehicle is powered by liquid nitrogen, which is stored in a tank. The engine works by heating the liquid nitrogen in a heat exchanger, extracting heat from the ambient air and using the resulting pressurized gas to operate a piston or rotary engine. Vehicles propelled by liquid nitrogen have been demonstrated, but are not used commercially.Liquid nitrogen propulsion may also be incorporated in hybrid systems, e.g., battery electric propulsion and fuel tanks to recharge the batteries. This kind of system is called a hybrid liquid nitrogen-electric propulsion. Additionally, regenerative braking can also be used in conjunction with this system.A liquid nitrogen economy is a hypothetical proposal for a future economy in which the primary form of energy storage and transport is liquid nitrogen. It is proposed as an alternative to liquid hydrogen in some transport modes and as a means of locally storing energy captured from renewable sources. An analysis of this concept provides insight into the physical limits of all energy conversion schemes. Liquid nitrogen is generated by cryogenic or Stirling engine coolers that liquefy the main component of air, nitrogen (N2). The cooler can be powered by electricity or through direct mechanical work from hydro or wind turbines.Liquid nitrogen is distributed and stored in insulated containers. The insulation reduces heat flow into the stored nitrogen; this is necessary because heat from the surrounding environment boils the liquid, which then transitions to a gaseous state. Reducing inflowing heat reduces the loss of liquid nitrogen in storage. The requirements of storage prevent the use of pipelines as a means of transport. Since long-distance pipelines would be costly due to the insulation requirements, it would be costly to use distant energy sources for production of liquid nitrogen. Petroleum reserves are typically a vast distance from consumption but can be transferred at ambient temperatures.Liquid nitrogen consumption is in essence production in reverse. The Stirling engine or cryogenic heat engine offers a way to power vehicles and a means to generate electricity. Liquid nitrogen canalso serve as a direct coolant for refrigerators, electrical equipment and air conditioning units. The consumption of liquid nitrogen is in effect boiling and returning the nitrogen to the atmosphere. Liquid nitrogen vehicles are comparable in many ways to electric vehicles, but use liquid nitrogen to store the energy instead of batteries. Their potential advantages over other vehicles include:
• 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
• 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.
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 available in public refueling stations nor is there a distribution system in place.
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:
A liquid nitrogen car with a 60-gallon tank will have a potential range of up to 200 miles, or more than twice that of a typical electric car
Why not commercialized?
Even though the technology is 10 to 12 years old, still it has not come to the market for two reasons.
SO due to the nitrogen abundance and its property of inertness and zero emissions we would see the world filled with car that would be propelled by nitrogen everlasting.
The scope of cryogenics has expanded widely from basic military and space applications to various civil applications. Already Infrared sensors are being increasingly used for fire detection alarm systems, energy conservation thermo graphic analysis, astronomical observations, and medical thermo graphic analysis for early Cancer detection.
The future developments are expected to lead towards disposable miniature 80 K cryogenics. Ever since the introduction of cryogenic nitrogen, it has found applicability in practically all fields because of its higher efficiency as compared to cryogenics based on other refrigerating cycles Cryogenics offer immense scope for the researchers and scientists for challenging ideas for new developments. Thus we conclude that the cryogenic nitrogen are playing a very important role in the researches and applications of its liquefaction, preservation and super cooling processes In a real sense, the more such vehicles are used, the cleaner the air will become if the liquefaction process is driven by non-polluting energy sources. 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.
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