CONTENTS

ABSTRACT

INTRODUCTION

THEORY BEHIND CRYOCAR

WORKING

BLOCK DIAGRAM OF CRYOCAR

ADVANTAGE

ABSTRACT

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. 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

INTRODUCTION

INTRODUCTION

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.

THEORY BEHIND CRYOCAR

THEORY BEHIND CRYOCAR The basic idea of the LN2 propulsion

system is to utilize the atmosphere as a heat source & a cryogen as a heat sink in thermal power cycle

This is a contrast to typical thermal engines which utilize an energy source at temperature significantly above ambient & use atmosphere as a heat sink

The both case the efficiency of conversion of thermal energy of the source to work (W) is limited by a Carnot efficiency

Since dU is an exact differential, its integral over any closed loop is zero and it follows that the area inside the loop on a T-S diagram is equal to the total work performed if the loop is traversed in a clockwise direction, and is equal to the total work done on the system as the loop is traversed in a counter clockwise direction

The efficiency η is defined to be

o

where

W is the work done by the system (energy exiting the system as work),

QH is the heat put into the system (heat energy entering the system),

TC is the absolute temperature of the cold reservoir, and

TH is the absolute temperature of the hot reservoir.

SB is the maximum system entropy

SA is the minimum system entropy

It can be seen from the above diagram, that for any cycle operating between temperatures TH and TC, none can exceed the efficiency of a Carnot cycle.

A real engine (left) compared to the Carnot cycle (right).

The entropy of a real material changes with temperature.

This change is indicated by the curve on a T-S diagram.

For this figure, the curve indicates a vapor-liquid equilibrium (See Rankine cycle ). Irreversible systems and losses of heat (for example, due to friction) prevent the ideal from taking place at every step.

WORKING

WORKING

A car powered by liquid nitrogen may be seen cruising the streets of Bishops Stortford.

Cylinder injection of a heat transfer fluid followed by liquefied gas raises efficiency to a point where fuel costs are comparable with petrol, but with no pollution.

As well as solving a problem which has long bugged all Rankine cycle engines, it leads to vehicles which are totally pollution free, without the cost and weight penalties incurred by batteries, and are also

intrinsically safe, a matter of great interest to the oil and gas industries.

The idea of providing forward motion from the boiling of a liquid and the subsequent expansion of a gas has been around since the end of the eighteenth century. While much used in the age of steam, the problems of heat transfer result in very poor thermal efficiencies unless the machines are of power station size.

The most efficient steam locomotives ever built, the American Union Pacific 'Big Boys' are said to have attained 14%, while the best achieved in Britain was

around 8 to 9%. Much the same pertains to another idea kicked around for more than a few years - running cars on liquid nitrogen, allowed to boil and expand using heat from the ambient environment.

The two liquid nitrogen powered developments most prominent on the World Wide Web are one at the University of Washington, now abandoned, and one at the University of North Texas.

The best the latter team seems to have achieved is to be able to power a car for 24km using 180litres of liquid nitrogen.

Where all the liquid nitrogen engines until now have fallen down is that while they make use of the expansion effect of liquid nitrogen boiling at 77 deg K, they fail to make full use of the expansion of that gas from 77 deg K to ambient 300 K, and keep it at ambient as it is expanded.

The efficiency of a heat engine depends on the difference between source and sink temperatures being as far apart as possible.

Failure to keep the temperature of the gas up during expansion results in a heat engine which very much less than optimally efficient.

A particular difficulty with nitrogen is that typical of gases in general, it is a good thermal insulator, making it difficult to transfer heat into the gas unless it is turbulent.

One solution suggested by the University of Washington was to make an engine using a lot of small cylinders, each only 10mm across but with a 100mm stroke.

Another of their ideas required building a radiator into the cylinder head, and another, a 110kg external heat exchanger.

The University of North Texas suggests injecting a 'hydraulic fluid'

into the cylinder along with the nitrogen, in order to provide an internal source of heat and also lubrication.

The University does not seem to have ever either tried or developed this, but in making the suggestion in a paper published in November 2001, the team put its fingers on the breakthrough which Peter Dear man has been exploiting.

His engine is two strokes.

The induction stroke starts by drawing in the heat exchange fluid, which in his case is a conventional

mix of ethylene glycol based car anti-freeze and water.

Liquid nitrogen is then injected subsequently from a separate nozzle. (If it was injected simultaneously, the liquid nitrogen would freeze the heat transfer fluid as it entered, blocking the injection port).

The heat transfer fluid possesses sufficient heat capacity to both boil the liquid nitrogen and heat it all the way up to ambient temperature.

The pressure pushes the piston down the cylinder, and as it does so, it absorbs more heat from the heat

transfer fluid to maintain its temperature at ambient.

At bottom dead centre, the exhaust valve opens, and the expanded nitrogen and heat transfer fluid are allowed to escape.

Before reaching the atmosphere, the mixture passes through a separator to recover the heat transfer fluid. The latter passes through a radiator to warm it up fully to ambient on its way back to the cylinder.

The prototype 400cc single cylinder engine has been fitted into an 'A' registration Ford Orion. Dearman says that it allows the car to be driven at up to 20mph and achieves a mileage of 1mile/litre.

At a cost from Air Products of 10p/litre, this allows the car to achieve a similar fuel cost per mile to that achieved using petrol. A new two cylinder engine with twice the powerouptut is now undergoing tests.

ADVANTAGE

ADVANTAGE THIS ZERO EMISSION PROPULSION

CONCEPT OFFERS MANY ENVIRONMENTAL ADVANTAGES OVER INTERNAL COMBUSTION ENGINES AND ELECTROCHEMICAL BATTERY VEHICLES.

IT HAS LOW OPERATING COSTS. IT LOW AMPLE PROPULSIVE POWER

AND REASONABLE ROUND TRIP ENERGY EFFICIENCY.

WE REFER THIS ZEV AS THE”CRYOMOBILE.”

CONCLUSION

CONCLUSION

OUR PROJECT ON-LINE INSPECTION CRYOCAR IS SUCCESSFULLY COMPLETED AND ITS WORKING IS SATISFIED.

ADVATAGE OF USING OUR PROJECT IN AN INDUSTRY THE NEED FOR WORKERS IN THE PROCESSING STATION CAN BE ELIMINATED.

THE CHANCE OF ERROR CAN ALSO BE ELIMINATED.

THE FAULTS CANE BE EASILY IDENTIFIED.

THEAUTOMATIC INSPECTION IN A MANUFACTURING COMPANY IS COMPLETET AND MONITORED BY THE MICROCONTROLLER UNIT.

REFERENCE

REFERENCE

WWW.aa.washingtion.edu/ aerp/cryocar -cryocar performance Details.

McCosh,”Emerging Technologies for the supercar,” popular science , june 1994.

Knowlen, c., Hertzberg, A., and mattick , “automotive propulsion using liquid

Nitrogen,” AIAA Paper 94-3349, June, 1994.