CRYOCAR

CRYOCAR

Cryogens are effective thermal storage medium which can be used for automotive propulsion, that boils at a temperature below about 110k. Cryogens are effective thermal storage media which, when used for automotive purposes, offer significant advantages over current and proposed electrochemical battery technologies, both in performance and economy. An automotive propulsion concept is presented which utilizes liquid nitrogen as the working fluid for an open Rankine cycle. The principle of operation is like that of a steam engine, except there is no combustion involved. An automotive propulsion concept is present with open Rankine cycle which utilise liquid nitrogen as work fluid. Pressurised liquid nitrogen(LN2) can be Vaporised by only heat input to engine which is supplied by ambient heat exchanger, resulting in easy propulsion of automobile Refill of LN2 requires only few minutes.

                                             Liquid nitrogen is pressurized and then vaporized in a heat exchanger by the ambient temperature of the surrounding air. The resulting high - pressure nitrogen gas is fed to the engine converting pressure into mechanical power. The only exhaust is nitrogen. The usage of cryogenic fuels has significant advantage over other fuel. Also, factors such as production and storage of nitrogen and pollutants in the exhaust give advantage for the cryogenic fuels. The importance of cars in the present world is increasing day by day. There are various factors that influence the choice of the car. These include performance, fuel, pollution etc. As the prices for fuels are increasing and the availability is decreasing we have to go for alternative choice.

                                     Here an automotive propulsion concept is presented which utilizes liquid nitrogen as the working fluid for an open Rankine cycle. When the only heat input to the engine is supplied by ambient heat exchangers, an automobile can readily be propelled while satisfying stringent tailpipe emission standards. Nitrogen propulsive systems can provide automotive ranges of nearly 400 kilometres in the zero emission mode, with lower operating costs than those of the electric vehicles currently being considered for mass production. In geographical regions that allow ultra-low emission vehicles, the range and performance of the liquid nitrogen automobile can be significantly extended by the addition of a small efficient burner. Some of the advantages of a transportation infrastructure based on liquid nitrogen are that recharging the energy storage system only requires minutes and there are minimal environmental hazards associated with the manufacture and utilization of the cryogenic "fuel". The basic idea of nitrogen propulsion system is to utilize the atmosphere as the heat source. This is in contrast to the typical heat engine where the atmosphere is used as the heat sink.

  

Cryogenic Heat Engine

It is an 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(LN2)

Liquid Nitrogen is the 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.

Liquefaction of LN2

Main Components of the Engine

A pressurized tank to store liquid nitrogen. Pressuring 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.

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.

Disadvantages

  è 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.

  è If nitrogen car is kept in a poorly ventilated space and, if

     there is a nitrogen leaks off, it could prove fatal.

  è 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.