Cryocar
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03-04-2010, 06:13 PM


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. 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

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 kilometers 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.

HISTORY

The LN2000 is an operating proof-of-concept test vehicle, a converted 1984 Grumman-Olson Kubvan mail delivery van. Applying LN2 as a portable thermal storage medium to propel both commuter and fleet vehicles appears to be an attractive means to meeting the ZEV regulations soon to be implemented. Pressurizing the working fluid while it is at cryogenic temperatures, heating it up with ambient air, and expanding it in reciprocating engines is a straightforward approach for powering pollution free vehicles. Ambient heat exchangers that will not suffer extreme icing will have to be developed to enable wide utility of this propulsion system.

Since the expansion engine operates at sub-ambient temperatures, the potential for attaining quasi-isothermal operation appears promising. The engine, a radial five-cylinder 15-hp air motor, drives the front wheels through a five-speed manual Volkswagen transmission. The liquid nitrogen is stored in a thermos-like stainless steel tank. At present the tank is pressurized with gaseous nitrogen to develop system pressure but a cryogenic liquid pump will be used for this purpose in the future. A preheater, called an economizer, uses leftover heat in the engine's exhaust to preheat the liquid nitrogen before it enters the heat exchanger. The specific energy densities of LN2 are 54 and 87 W-h/kg-LN2 for the adiabatic and isothermal expansion processes, respectively, and the corresponding amounts of cryogen to provide a 300 km driving range would be 450 kg and 280 kg. Many details of the application of LN2 thermal storage to ground transportation remain to be investigated; however, to date no fundamental technological hurdles have yet been discovered that might stand in the way of fully realizing the potential offered by this revolutionary propulsion concept
Use Search at http://topicideas.net/search.php wisely To Get Information About Project Topic and Seminar ideas with report/source code along pdf and ppt presenaion
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sumit kuta
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16-07-2010, 12:19 PM

please send a full project and implimentation report on cyrocar
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uduppayil
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25-07-2010, 09:55 PM

Hai
please send me more about cryo car
regards
uduppayil
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vineeth505519
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16-08-2010, 06:37 PM

send me details of cryocar
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seminar surveyer
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23-12-2010, 01:18 PM

Prepared by:Suhas Upadhyaya


.pptx   10TH13F-Cryocar.pptx (Size: 124.6 KB / Downloads: 378)

What is a Cryocar?

It is a liquid nitrogen powered vehicle.

Propulsion systems are cryogenic heat engines in which a cryogenic substance is used as a heat sink.

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(LN2)

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.

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summer project pal
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11-01-2011, 08:52 PM

The full version of the above report is given here for your convenience:
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 fuels. Also, factors such as production and storage of nitrogen and pollutants in the exhaust give advantage for the cryogenic fuels.


.rar   cryocar full report.rar (Size: 41.66 KB / Downloads: 316)


Chapter 1
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 kilometers 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.







Chapter 2
HISTORY

Researchers at the University of Washington are developing a new zero-emission automobile propulsion concept that uses liquid nitrogen as the fuel. The principle of operation is like that of a steam engine, except there is no combustion involved. Instead, liquid nitrogen at –320° F (–196° C) is pressurized and then vaporized in a heat exchanger by the 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. 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 the major constituent of our atmosphere.

The LN2000 is an operating proof-of-concept test vehicle, a converted 1984 Grumman-Olson Kubvan mail delivery van. Applying LN2 as a portable thermal storage medium to propel both commuter and fleet vehicles appears to be an attractive means to meeting the ZEV regulations soon to be implemented. Pressurizing the working fluid while it is at cryogenic temperatures, heating it up with ambient air, and expanding it in reciprocating engines is a straightforward approach for powering pollution free vehicles. Ambient heat exchangers that will not suffer extreme icing will have to be developed to enable wide utility of this propulsion system. Since the expansion engine operates at sub-ambient temperatures, the potential for attaining quasi-isothermal operation appears promising. The engine, a radial five-cylinder 15-hp air motor, drives the front wheels through a five-speed manual Volkswagen transmission. The liquid nitrogen is stored in a thermos-like stainless steel tank. At present the tank is pressurized with gaseous nitrogen to develop system pressure but a cryogenic liquid pump will be used for this purpose in the future. A preheater, called an economizer, uses leftover heat in the engine's exhaust to preheat the liquid nitrogen before it enters the heat exchanger. The specific energy densities of LN2 are 54 and 87 W-h/kg-LN2 for the adiabatic and isothermal expansion processes, respectively, and the corresponding amounts of cryogen to provide a 300 km driving range would be 450 kg and 280 kg. Many details of the application of LN2 thermal storage to ground transportation remain to be investigated; however, to date no fundamental technological hurdles have yet been discovered that might stand in the way of fully realizing the potential offered by this revolutionary propulsion concept.

Chapter 3
LN2000'S LIQUID NITROGEN PROPULSION CYCLE



Figure 1: LN2000 liquid nitrogen propulsion cycle.



3.1 PARTS OF A LIQUID NITROGEN PROPULSION CYCLE

The main parts of a liquid nitrogen propulsion system are:

1. Cryogen Storage Vessel.
2. Pump.
3. Economizer.
4. Expander Engine.
5. Heat exchanger.

The parts and their functions are discussed in detail below:

3.1.1 Cryogen Storage Vessel:
The primary design constraints for automobile cryogen storage vessels are: resistance to deceleration forces in the horizontal plane in the event of a traffic accident, low boil-off rate, minimum size and mass, and reasonable cost. Crash-worthy cryogen vessels are being developed for hydrogen-fueled vehicles that will prevent loss of insulating vacuum at closing speeds of over 100 km/h.18 Moderately high vacuum (10-4 torr) with super insulation can provide boil-off rates as low as 1% per day in 200 liter (53 gal) containers. Using appropriate titanium or aluminum alloys for the inner and outer vessels, a structurally reinforced dewar could readily have a seven-day holding period. The cost of a mass produced, 200 liter automotive tank for liquid hydrogen containment has been estimated to be between $200 and $400 (in 1970 dollars). Thus the expense of a 400 liter LN2 tank (or two 200 liter tanks) is expected to be reasonable.


3.1.2 Pump:
The pump is used to pump the liquid nitrogen into the engine. The pump which are used for this purpose have an operating pressure ranging between 500 – 600 Psi. As the pump, pumps liquid instead of gas, it is noticed that the efficiency is high.

3.1.3 Economizer:
A preheater, called an economizer, uses leftover heat in the engine's exhaust to preheat the liquid nitrogen before it enters the heat exchanger. Hence the economizer acts as a heat exchanger between the incoming liquid nitrogen and the exhaust gas which is left out. This is similar to the preheating process which is done in compressors. Hence with the use of the economizer, the efficiency can be improved. The design of this heat exchanger is such as to prevent frost formation on its outer surfaces.
3.1.4 Expander:
The maximum work output of the LN2 engine results from an isothermal expansion stroke. Achieving isothermal expansion will be a challenge, because the amount of heat addition required during the expansion process is nearly that required to superheat the pressurized LN2 prior to injection. Thus, engines having expansion chambers with high surface-to-volume ratios are favored for this application. Rotary expanders such as the Wankel may also be well suited. A secondary fluid could be circulated through the engine block to help keep the cylinder walls as warm as possible. Multiple expansions and reheats can also be used although they require more complicated machinery.
Vehicle power and torque demands would be satisfied by both throttling the mass flow of LN2 and by controlling the cut-off point of N2 injection, which is similar to how classical reciprocating steam engines are regulated. The maximum power output of the propulsion engine is limited by the maximum rate at which heat can be absorbed from the atmosphere. The required control system to accommodate the desired vehicle performance can be effectively implemented with either manual controls or an on-board computer. The transient responses of the LN2 power plant and the corresponding operating procedures are topics to be investigated.
3.1.5 Heat Exchanger:
The primary heat exchanger is a critical component of a LN2 automobile. Since ambient vaporizers are widely utilized in the cryogenics and LNG industries, there exists a substantial technology base. Unfortunately, portable cryogen vaporizers suitable for this new application are not readily available at this time. To insure cryomobile operation over a wide range of weather conditions, the vaporizer should be capable of heating the LN2 at its maximum flow rate to near the ambient temperature on a cold winter day. Since reasonable performance for personal transportation vehicles can be obtained with a 30 kW motor, the heat exchanger will be sized accordingly. For an isothermal expansion engine having an injection pressure of 4 MPa, the heat absorbed from the atmosphere can, in principle, be converted to useful mechanical power with about 40% efficiency. Thus the heat exchanger system should be prudently designed to absorb at least 75 kW from the atmosphere when its temperature is only 0°C.
To estimate the mass and volume of the primary heat exchanger, it was modeled as an array of individually fed tube elements that pass the LN2 at its peak flow rate without excessive pressure drop. Each element is a 10 m long section of aluminum tubing having an outside diameter of 10 mm and a wall thickness of 1 mm. They are wrapped back and forth to fit within a packaging volume having 0.5 m x 0.4 m x 0.04 m dimensions and are arrayed in the heat exchanger duct. Incoming air will pass through a debris deflector and particulate filter before encountering the elements. An electric fan will draw the air through the duct when the automobile is operating at low velocities or when above normal power outputs are required.
The tube exterior heat transfer coefficient is based on that for a cylinder in cross flow and the internal heat transfer is for fully developed turbulent flow. The bulk temperature of the air is assumed to decrease across each tube row as determined from energy conservation and the pressure drop is determined for the whole tube bank. The heat transfer calculations also account for N2 pressure drop and variations in its thermodynamic properties in the tube elements. Some of the important phenomena not considered at this stage of analysis were the effects of transient LN2 flow rates, start up, frost accumulation, tube fins, and axial thermal conduction.
The formation of rime ice is highly probable. The atmospheric moisture will be removed relatively quickly as the ambient air is chilled over the first few tube rows, leaving extremely dry air to warm up the coldest parts at the rear of the heat exchanger where the LN2 enters. Surface coatings such as Teflon can be used to inhibit ice build up and active measures for vibrating the tube elements may also be applied. However, these approaches may not be necessary since high LN2 flow rates are only needed during times of peak power demand and the heat exchanger elements are much longer than necessary to elevate the LN2 temperature to near ambient at the lower flow rates required for cruise. Thus, the frosted tube rows may have ample opportunity to de-ice once the vehicle comes up to speed.
Even though inclement weather will certainly degrade the performance of the cryomobile, it will not preclude effective operation. If the propulsion system operating conditions were such that the LN2 could only be heated to 250 K prior to injection, the flow rates of LN2 for the isothermal and adiabatic cycles to generate 30 kW would be 115 gm/sec and 187 gm/sec, respectively. The previously described heat exchanger configuration can theoretically heat the higher LN2 flow rate to 250 K with 25 radiator elements when the vehicle is traveling at 25 km/sec (16 mi/h) and the ambient air temperature is only 0°C. The LN2 viscous pressure drop would be about 0.05 MPa, which is easily compensated for with the cryogen pump. The electric fan would require approximately 1.5 kW to accelerate the air and overcome the 400 Pa pressure drop through the heat exchanger if the vehicle were standing still. Since each element is 0.76 kg, the total tubing mass would be 19 kg. If the same mass was added by the manifolds and duct then the net mass of the heat exchanger would be less than 40 kg. When operating on a typical California day, it is expected that this over-designed cryogen vaporizer will readily heat the LN2 up to ambient temperature without any appreciable icing.


Chapter 4
POWER CYCLE

There are many thermodynamic cycles available for utilizing the thermal potential of liquid nitrogen. These range from the Brayton cycle, to using two- and even three-fluid topping cycles, to employing a hydrocarbon-fueled boiler for superheating beyond atmospheric temperatures. The easiest to implement, however, and the one chosen for this study, is shown below. This system uses an open Rankine cycle. The temperature – entropy diagram for the open rankine cycle is described below.



Figure 2: Temperature - entropy diagram for the open Rankine cycle.

State 1 is the cryogenic liquid in storage at 0.1 MPa and 77 K. The liquid is pumped up to system pressure of 4 MPa (supercritical) at state 2 and then enters the economizer. State 3 indicates N2 properties after it is being preheated by the exhaust gas. Further heat exchange with ambient air brings the N2 to 300 K at state 4, ready for expansion. Isothermal expansion to 0.11 MPa at state 5 would result in the N2 exhaust having enough enthalpy to heat the LN2 to above its critical temperature in the economizer, whereas adiabatic expansion to state 6 would not leave sufficient enthalpy to justify its use. The specific work output would be 320 and 200 kJ/kg-LN2 for these isothermal and adiabatic cycles, respectively, without considering pump work. While these power cycles do not make best use of the thermodynamic potential of the LN2, they do provide specific energies competitive with those of lead-acid batteries.


Chapter 5
Performance of the open Rankine cycle

The thermodynamic and economic performances of the adiabatic and isothermal modes of the open Rankine cycle are shown in Table 1. These figures are based on the specifications of a modified Honda CRX for which performance data were available. The cost of 2.6¢ per kg-LN2 was derived assuming only the energy cost of production.
Process Adiabatic Isothermal
Pump Work: 6 kJ/kg-LN2 6 kJ/kg-LN2
Net Work Out: 194 kJ/kg-LN2 314 kJ/kg-LN2
Heat Input: 419 kJ/kg-LN2 750 kJ/kg-LN2
Energy Density: 54 W-h/kg-LN2 87 W-h/kg-LN2
LN2 Flow Rate:† 1.5 kg/km 0.93 kg/km
Operating Cost:‡ 3.9 ¢ /km 2.4 ¢ /km
† Based on 7.8 kW for highway cruise at 97 km/h.
‡ Based on 2.6¢ per kg-LN2 production cost.

Table1: Performance of the open Rankine cycle.



Chapter 6
LIQUID NITROGEN MANUFACTURE

The cost of the LN2 "fuel" is expected to be reasonable. The primary expense for producing LN2 is the energy cost for compression of air. Cryogenic separation of nitrogen from other condensables in air typically requires only a very small fraction of the total energy, so the ideal work to manufacture LN2 from air is very nearly that for using nitrogen as a feedstock. This work is exactly the reversible work obtainable from an ideal cryo-engine, 769 kJ/kg. The actual work required in a modern LN2 plant is 2.0-2.5 times the minimum, or 1540-1920 kJ/kg. Assuming an industrial electric rate for interruptible power of 5¢/kW-h, the energy cost would amount to 2.6¢/kg-LN2, in accord with delivery prices of LN2 in large quantities. Marketing the other commercially important components of air will help offset the LN2 production costs. Since the equipment needed for air liquefaction can be powered solely by electricity, it is conceivable to decentralize the "fuel" manufacturing process and to place small scale production facilities at the LN2 dispensing sites. A cost-benefit analysis is needed to determine the smallest air liquefaction machinery that can be used to produce LN2 in an economical manner.





Chapter 7
THERMAL STORAGE EFFECTIVENESS:

Because the design and expense of the cryomobile are driven primarily by the cryogen heat sink, it is useful to characterize performance by a "sink efficiency",  = W/Ql, i.e. the inverse of the coefficient of performance for a refrigerator. For a reversible cycle with fixed sink and source temperatures the ideal sink efficiency is  = Th/Tl  1, or 2.9 for Tl = 77 K and Th = 300 K. If only the enthalpy of evaporation of LN2 (hfg = 199 kJ/kg) is used to sink such an engine, the ideal work output is 576 kJ/kg of LN2. This specific energy is significantly higher than the 180-300 kJ/kg achieved with lead-acid batteries.
Additional potential remains for heat sinking by the cold N2 vapor, and the ideal work recoverable from an expansion engine as LN2 is evaporated at 77 K, then brought up to ambient temperature (To = 300 K), is given by the difference in thermodynamic availability,  = h  sTo, between liquid and ambient states. This "reversible work" for LN2 is Wr = 769 kJ/kg-N2 and the corresponding sink efficiency is  = 1.78. Thus, only a small fraction of the reversible work needs to be recovered to provide the cryomobile with a driving range commensurate with that of battery-powered vehicles of comparable weight. The relative merits of different ZEV technologies must also be evaluated on considerations other than performance such as environmental friendliness and commuting utility. While the specific energy of LN2 or batteries is far below that of hydrocarbon fuels, the internal combustion engine cars cannot operate without polluting emissions and thus should not be compared with ZEVs.


Chapter 8
ADVANTAGES


Studies indicate that liquid nitrogen automobiles will have significant performance and environmental advantages over electric vehicles. 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. Furthermore, a liquid nitrogen car will be much lighter and refilling its tank will take only 10-15 minutes, rather than the several hours required by most electric car concepts. Motorists will fuel up at filling stations very similar to today's gasoline stations. When liquid nitrogen is manufactured in large quantities, the operating cost per mile of a liquid nitrogen car will not only be less than that of an electric car but will actually be competitive with that of a gasoline car.


8.1. As compared to fossil fuels:
The process to manufacture liquid nitrogen in large quantities can be environmentally very friendly, even if fossil fuels are used to generate the electric power required. The exhaust gases produced by burning fossil fuels in a power plant contain not only carbon dioxide and gaseous pollutants, but also all the nitrogen from the air used in the combustion. By feeding these exhaust gases to the nitrogen liquefaction plant, the carbon dioxide and other undesirable products of combustion can be condensed and separated in the process of chilling the nitrogen, and thus no pollutants need be released to the atmosphere by the power plant. The sequestered carbon dioxide and pollutants could be injected into depleted gas and oil wells, deep mine shafts, deep ocean subduction zones, and other repositories from which they will not diffuse back into the atmosphere, or they could be chemically processed into useful or inert substances. Consequently, the implementation of a large fleet of liquid nitrogen vehicles could have much greater environmental benefits than just reducing urban air pollution as desired by current zero-emission vehicle mandates.
8.2. Comparing Energy Densities:

Figure 3: Specific energy for various energy storage media.

The above figure shows how a liquid nitrogen based propulsion cycle fares against the various electrochemical storage media mentioned earlier. Specific energy is a useful figure of merit because it correlates closely with range. Even the next generation, nickel-metal hydride battery, only matches the performance of the isothermal open Rankine cycle. And the open Rankine is not the highest performing cycle available. By adding a, methane topping cycle, upwards of 160 W-hr/kg can be achieved.

Chapter 9
TECHNICAL ISSUES

9.1. Range Extension and Power Boosting:
Range extension and performance enhancement can be realized by heating the LN2 to above ambient temperatures with the combustion of a relatively low pollution fuel such as ethanol or natural gas. By increasing the gaseous N2 temperature to 500 K, the specific work at 4 MPa for the adiabatic engine is increased by 60% to make it nearly the same as the work from an isothermal expansion engine operating at 300 K. In this particular propulsive cycle an extra superheat of 200°C results in only a 30% increase in specific power. Thus the advantage of operating above ambient temperature depends, in part, on how isothermal the expansion process can be made to be.
There is also the intriguing possibility of storing energy for boosting power or extending range by applying a medium that undergoes a phase change to the final superheater segment of the heat exchanger system. Ideally the phase change material would be slowly "recharged" as it absorbs heat from the atmosphere while the vehicle is parked and during cruise when peaking power is not required. Fast recharging with electric heaters may also be considered. We recognize that this added complexity must compete in mass and compactness with the alternative of just carrying more LN2.


Chapter 10
CONCLUSION

The potential for utilizing the available energy of liquid nitrogen for automotive propulsion looks very promising. Time to recharge (refuel), infrastructure investment, and environmental impact are among the issues to consider, in addition to range and performance, when comparing the relative merits of different ZEV technologies. The convenience of pumping a fluid into the storage tank is very attractive when compared with the typical recharge times associated with lead-acid batteries. Manufacturing LN2 from ambient air inherently removes small quantities of atmospheric pollutants and the installation of large-scale liquefaction equipment at existing fossil-fuel power stations could make flue gas condensation processes economical and even eliminate the emissions of CO2.

REFERENCE

WWW. aa. washington. edu
Heat transfer, J.P. Holman

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sudeep9666
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02-03-2011, 12:28 PM

here is the detailed report on cryocar

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 counterclockwise 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 HASLOW OPERATING COSTS.
• IT LOW AMPLE PROPULSIVE POWERAND REASONABLE ROUND TRIP ENERGY EFFICIENCY.
• WE REFER THIS ZEV AS THE”CRYOMOBILE.”








CONCLUSION







CONCLUSION
• OUR PROJECT ON-LINE INSPECTION CRYOCAR IS SUCCESSFULLY COMPLETEDAND 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.


















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.doc   cryocar-report.doc (Size: 169.5 KB / Downloads: 144)
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.
CHAPTER 1
1.1 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 kilometers in the zero emission modes, 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.
1.2 HISTORY
The LN2000 is an operating proof-of-concept test vehicle, a converted 1984 Grumman-Olson Kubvan mail delivery van. Applying LN2 as a portable thermal storage medium to propel both commuter and fleet vehicles appears to be an attractive means to meeting the ZEV regulations soon to be implemented. Pressurizing the working fluid while it is at cryogenic temperatures, heating it up with ambient air, and expanding it in reciprocating engines is a straightforward approach for powering pollution free vehicles. Ambient heat exchangers that will not suffer extreme icing will have to be developed to enable wide utility of this propulsion system.
Since the expansion engine operates at sub-ambient temperatures, the potential for attaining quasi-isothermal operation appears promising. The engine, a radial five-cylinder 15-hp air motor, drives the front wheels through a five-speed manual Volkswagen transmission. The liquid nitrogen is stored in a thermos-like stainless steel tank. At present the tank is pressurized with gaseous nitrogen to develop system pressure but a cryogenic liquid pump will be used for this purpose in the future. A preheater, called an economizer, uses leftover heat in the engine's exhaust to preheat the liquid nitrogen before it enters the heat exchanger. The specific energy densities of LN2 are 54 and 87 W-h/kg-LN2 for the adiabatic and isothermal expansion processes, respectively, and the corresponding amounts of cryogen to provide a 300 km driving range would be 450 kg and 280 kg. Many details of the application of LN2 thermal storage to ground transportation remain to be investigated; however, to date no fundamental technological hurdles have yet been discovered that might stand in the way of fully realizing the potential offered by this revolutionary propulsion concept.
1.3 DESCRIPTION
Liquid nitrogen is generated by cryogenic or Sterling 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 Sterling engine or cryogenic heat engine offers a way to power vehicles and a means to generate electricity. Liquid nitrogen can also 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.
CHAPTER 2
2.1 FACTORS EFFECTING CRYOCARS
COST OF PRODUCTION

Liquid nitrogen production is an energy-intensive process. Currently practical refrigeration plants producing a few tons/day of liquid nitrogen operate at about 50% of Carnot efficiency.
ENERGY DENSITY OF LIQUID NITROGEN
Any process that relies on a phase-change of a substance will have much lower energy densities than processes involving a chemical reaction in a substance, which in turn have lower energy densities than nuclear reactions. Liquid nitrogen as an energy store has a low energy density. Liquid hydrocarbon fuels by comparison have a high energy density. A high energy density makes the logistics of transport and storage more convenient. Convenience is an important factor in consumer acceptance. The convenient storage of petroleum fuels combined with its low cost has led to an unrivaled success. In addition, a petroleum fuel is a primary energy source, not just an energy storage and transport medium.
The energy density — derived from nitrogen's isobaric heat of vaporization and specific heat in gaseous state — that can be realized from liquid nitrogen at atmospheric pressure and zero degrees Celsius ambient temperature is about 97 watt-hours per kilogram (W-hr/kg). This compares with about 3,000 W-hr/kg for a gasoline combustion engine running at 28% thermal efficiency, 30 times the density of liquid nitrogen used at the Carnot efficiency.
For an isothermal expansion engine to have a range comparable to an internal combustion engine, an 350-litre (92 US gal) insulated onboard storage vessel is required [2]. A practical volume, but a noticeable increase over the typical 50-litre (13 US gal) gasoline tank. The addition of more complex power cycles would reduce this requirement and help enable frost free operation. However, no commercially practical instances of liquid nitrogen use for vehicle propulsion exist.
FROST FORMATION
Unlike internal combustion engines, using a cryogenic working fluid requires heat exchangers to warm and cool the working fluid. In a humid environment, frost formation will prevent heat flow and thus represents an engineering challenge. To prevent frost build up, multiple working fluids can be used. This adds topping cycles to ensure the heat exchanger does not fall below freezing. Additional heat exchangers, weight, complexity, efficiency loss, and expense, would be required to enable frost free operation.
SAFETY
However efficient the insulation on the nitrogen fuel tank, there will inevitably be losses by evaporation to the atmosphere. If a vehicle is stored in a poorly ventilated space, there is some risk that leaking nitrogen could reduce the oxygen concentration in the air and cause asphyxiation. Since nitrogen is a colorless and odourless gas that already makes up 78 % of air, such a change would be difficult to detect.
Cryogenic liquids are hazardous if spilled. Liquid nitrogen can cause frostbite and can make some materials extremely brittle.
As liquid N2 is colder than 90.2K, oxygen from the atmosphere can condense. Liquid oxygen can spontaneously and violently react with organic chemicals, including petroleum products like asphalt
Since the liquid to gas expansion ratio of this substance is 1:694, a tremendous amount of force can be generated if liquid nitrogen is rapidly vaporized. In an incident in 2006 at Texas A&M University, the pressure-relief devices of a tank of liquid nitrogen were sealed with brass plugs. As a result, the tank failed catastrophically, and exploded.
TANKS
The tanks must be designed to safety standards appropriate for a pressure vessel, such as ISO 11439.
The storage tank may be made of:
Steel,
Aluminium,
Carbon fiber,
Kevlar,
Other materials or combinations of the above.
The fiber materials are considerably lighter than metals but generally more expensive. Metal tanks can withstand a large number of pressure cycles, but must be checked for corrosion periodically.
EMISSION OUTPUT
Like other non-combustion energy storage technologies, a liquid nitrogen vehicle displaces the emission source from the vehicle's tail pipe to the central electrical generating plant. Where emissions-free sources are available, net production of pollutants can be reduced.Emission control measures at a central generating plant may be more effective and less costly than treating the emissions of widely dispersed vehicles
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.ppt   CRYOCAR by Amol.ppt (Size: 1.23 MB / Downloads: 239)
CRYOCAR
Cryo - means cold
Genics - means science.
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.
It is a liquid nitrogen powered vehicle.
Propulsion systems are cryogenic heat engines in which a cryogenic substance is used as a heat sink.
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.
Cryoengine works on Rankin Cycle
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.
A pressurized tank to store liquid nitrogen.
Pressurant 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.
LN2 at –320 °F (-196 °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 N2 passing through the primary heat exchanger quickly reaches its boiling point.
The N2 expands to a gas with a pressure of 150 psi.
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
Conti……
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 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.
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 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.
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 yet available in public refueling stations.
The LN2 car can travel 15 miles on a full (48 gallon) tank of liquid nitrogen going 20 MPH.
Its maximum speed is over 35 MPH.
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.
Technology has certain limitations such speed, leakage hazard, generating liquid nitrogen etc.
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.
Research paper on “Liquid Nitrogen as a Non-Polluting Vehicle Fuel” by Mitty c. Plummer, Carlos A. Ordonez and Richard F. Reidy, University of North Texas.
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CRYOCAR



.pptx   CRYOCAR.pptx (Size: 1.17 MB / Downloads: 73)

Introduction:

The importance of automotives is increasing day by day especially in the field of cars. There are various factors that influence the choice of the car which include performance, fuel, pollution etc.
As the prices for fuels are increasing and the availability is decreasing we have to go for alternative choice.
At this point of view we have “CRYOCARS” as an alternative choice.
These cryocars uses cryogens as fuel.
Cryogen is nothing but a liquid, such as liquid nitrogen, that boils at a temperature below about 110 K (-160°C) and is used to obtain very low temperatures.
Uses liquid nitrogen as working fluid and hence it is also called as liquid nitrogen powered vehicle.

Why Liquid Nitrogen?

Liquid nitrogen is the liquefied form of the element “nitrogen” that is commercially produced by fractional distillation of liquid air.
Liquid Nitrogen is the cheapest, widely produced and most common cryogen.
It is mass produced in air liquefaction plants.
At normal pressure, liquid nitrogen boils at 77 K (−195.8°C or −320.4°F).
Easy to Liquefy.
Liquefaction of gases is physical conversion of a gas into a liquid state.
The conversion of Nitrogen gas to Liquid Nitrogen is done by the process of Fractional Distillation.
This process consists of two steps, the first relies on cooling the air to a very low temperature (i.e. converting it into a liquid), the second involves heating it up thus allowing each gas within the mixture to evaporate at its own boiling point.

Working Principle:

LN2 is pressurized and then vaporized in a heat exchanger by ambient temperature of the surrounding air.
This heat exchanger just like the radiator of a car.
Liquid N2 passing through the primary heat exchanger quickly reaches its boiling point as it gets vaporized at room temperature.
The pressurized N2 gas drives the motor with the help of an Expander.
The only exhaust is nitrogen, which is major constituent of our atmosphere.













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06-07-2012, 09:54 AM

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31-07-2012, 12:03 AM

good information.....want to more about it
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