A Seminar On A Liquid Nitrogen Vehicle Guided

A Seminar On A Liquid Nitrogen Vehicle Guided By: Sri. Rahul Gupta (Associate Professor) MED HBTI Kanpur Ankit Kumar Verma M. Tech[CAD], 3 rd Sem SR NO. 734/10 Roll No. 6004540001

Topics of Interest Introduction to the liquid nitrogen vehicle History Justifying the use of liquid nitrogen vehicle Cryogenic heat engines Production of liquid nitrogen Main components Principle of operation Open Rankine cycle

Topics of Interest Contd. Advantages Drawbacks Solutions to drawbacks Efficiency Reason for not being commercialized Conclusion and Reference

What is Liquid Nitrogen Vehicle? It is a vehicle which uses Cryogenic fluid(liquid nitrogen) as a working fluid. Propulsion system is a cryogenic heat engine in which a cryogenic substance is used as a heat sink. CRYOGENICS Cryogenic can be defined as the branch of the physics that deals with the study of the production of very low temperature (below − 150 °C, − 238 °F or 123 K) and the behavior of materials at those temperatures.

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. The vehicle (car) was named as LN 2000. It was a converted 1984 Grumman-Olson Kubvan mail delivery van.

A liquid nitrogen propelled car(LN 2000)

Why Nitrogen as a Vehicle Fuel? High cost and limited availability of fossil fuels like petrol and diesel. Due to high level of pollution associated with the combustion of fossil fuels the need of ZEV has been generated. (presently the battery powered electric vehicle is the only commercially available ZEV but not successful due to high initial cost, slow recharge and limited range). And the most important is the huge availability of Nitrogen gas(78% of air is nitrogen). Note: According to Petroleum Conservation and Research Association petroleum production will be at its peak in 2012 and is likely to decrease after that.

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.

Liquid Nitrogen(LN 2) 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.

P-T Chart showing Nitrogen Liquification

Inter cooler Atmospheric Dust Turbo Precipitator pumps Air passes LN 2 Expansion Fractional Insulated chamber Nozzle Distillation Dewar Flask Nitrogen cycle showing the production of liquid nitrogen

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.

Main Components of the Engine: �A pressurized tank(24 gallon) to store liquid nitrogen. �Pressurant bottles of N 2 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) LN 2 to form N 2 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 N 2 coming out from the pressurized tank taking heat from the exhaust.

Major components of the Nitrogen powered car

Setup position of various components of nitrogen powered car

Principle of Operation: �LN 2 at – 320 o. F (-196 o. 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 N 2 passing through the primary heat exchanger quickly reaches its boiling point. �The N 2 expands to a gas with a pressure of 150 KPa.

Liquid nitrogen energy conversion system

�The pressurized N 2 gas drives the motor. �The only exhaust is nitrogen, which is major constituent of our atmosphere. �Energy+N 2(l)-->N 2(g) Hence, there is no pollution produced by running this car.

Open Rankine Cycle Process The work done for simple adiabatic expansion with no heat admitted during expansion, Wadiabatic =Kr. Ta [1 -(P 2 / P 1) K-1/K]/ (K-1) Where Ta = 300 K, ambient temperature and K = 1. 4, the ratio of specific heats for nitrogen. The resulting Wadiabatic is 180 KJ/Kg of Nitrogen exhausted at 150 KPa.

Another limiting process is isothermal expansion from 3. 3 MPa to 120 KPa and the work can be easily computed as Wisothermal = r Ta ln (P 2/P 1) r = 0. 2968 (KJ/Kg. K) for nitrogen gas and Ta = 300 K. The result for Nitrogen is 291. 59 KJ/Kg.

Note: The Availability of working fluid N 2 relative to ambient conditions (Ta = 300 K) is 768 KJ/Kg. The available energy of the liquid N 2 is given by [|h|×(Ta – T 0)]/Ta which is equal to 570. 88 KJ/Kg. This available energy is almost 4 times the specific energy of Pb-acid batteries which is 144 KJ/Kg , where Ta and T 0 are the ambient and temperature of liquid nitrogen

(a) T-P chart of a single stage nitrogen expansion Total work achieved is 180 KJ/Kg (b) Specific work of various fluids in adiabatic and isothermal expanders

Advantages over electric cars: �A liquid nitrogen car is much lighter and refilling its tank takes only about 10 -15 minutes. �The exhaust produced by the car is environmental friendly. �A cryogenic car could have three times the range of an electric car of the same weight and no battery disposal concerns.

Drawbacks: �The N 2 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 N 2 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.

Probable Solutions: A tube within a tube design. N 2 passes back and forth inside a set of three nested tubes. By the time it reaches the outermost tubes, the N 2 is warm enough that the exterior wall of the tube remains above the freezing point of water. Route the exhaust from the fossil fuel power plants through cryogenic plants, so that the pollutants and the greenhouse gases could be condensed for later disposal

Efficiency: �The LN 2 car can travel 79 miles(127. 58 km) on a full 24 gallon(90 liter) tank of liquid nitrogen going 20 MPH. �Its maximum speed is over 35 MPH.

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.

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

References: http: //www. pcra. org/ “Petroleum conservation research association” "cryogenics" Encyclopædia Britannica http: //search. eb. com/eb/article? eu=28520]. Knowlen, C. , Hertzberg, A. , Mattick, A. T. , “Automotive Propulsion Using Liquid Nitrogen, ” AIAA 94 -3349, 1994. M. C. Plummer, C. A. Ordonez, R. F. Reidy, “Liquid Nitrogen as a Non. Polluting Vehicle Fuel”, C. Knowlen, A. T. Mattick, A. P. Bruckner and A. Hertzberg, “High Efficiency Energy Conversion Systems for Liquid Nitrogen Automobiles” Paper serial no. 981898 http: //www. autoexpo. in/ “ Auto expo 2012” Thomas B. North “Liquid nitrogen propulsion systems for automotive applications”

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