Cryogens Essay

Cryogens are effective thermal repositing media which, when use for self-propelled purposes, offer signifi pilet advantages over electric current and proposed electrochemical bombardment technologies, both in effect and economy. An self-propelled actuation concept is presented which utilizes eloquent newton as the working quiet for an open Rankine cycle. The principle of mathematical solve is like that of a steam engine, except there is no combustion involved. Liquid nitrogen is pressurized and and so vaporized in a take fire exchanger by the ambient temperature of the surrounding air. The resulting high pressure nitrogen gas is fed to the engine converting pressure into mechanical military unit. The only chuck out is nitrogen. The usage of cryogenic fuels has significant advantage over opposite fuels. Also, factors such(prenominal) as production and storage of nitrogen and pollutants in the obliterate make believe advantage for the cryogenic fuels.INTRODUCTIONTh e importance of cars in the present humanness is change magnitude day by day. There are various factors that put to work the choice of the car. These include performance, fuel, pollution etc. As the prices for fuels are increasing and the availability is decreasing we aim to go for alternative choice. Here an automotive propulsion concept is presented which utilizes liquifiable nitrogen as the working fluid for an open Rankine cycle. When the only light input to the engine is supplied by ambient heat exchangers, an automobile can readily be propelled while fulfill stringent tailpipe emission standards.Nitrogen propulsive systems can provide automotive ranges of close together(p)ly 400 kilometers in the zero emission mode, with lower in operation(p) exists than those of the electric vehicles currently being considered for mass production. In geographic regions that allow ultra low emission vehicles, the range and performance of the mobile nitrogen automobile can be signifi cantly extended by the addition of a small efficient burner. Some of the advantages of a expatriate infrastructure based on fluid nitrogen are that recharging the nil storage system only requires minutes and there are borderline environmental hazards associated with the manufacture and utilization of the cryogenic fuel. The basic sentiment of nitrogen propulsion system is to utilize the cash dispenser as the heat source. This is in contrast to the typical heat engine where the standard pressure is employ as the heat sink.PARTS OF A LIQUIDNITROGEN actuation CYCLEThe main parts of a suave nitrogen propulsion system are 1.Cryogen Storage Vessel. 2.Pump. 3.economiser. 4.Expander Engine. 5. enkindle exchanger. The parts and their functions are discussed in concomitant below Cryogen Storage Vessel The primary chassis constraints for automobile cryogen storage vessels are resistance to deceleration forces in the horizontal plane in the event of a traffic accident, low b cover-of f rate, minimum size and mass, and apt cost.PumpThe core is utilise to pump the liquid nitrogen into the engine. The pump which are used for this purpose have an operating pressure ranging amid 500 600 Psi. As the pump, pumps liquid instead of gas, it is noniced that the efficiency is high.EconomizerA preheater, called an economiser, uses leftover heat in the engines 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 procedure which is do 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 makeup on its outer surfaces.ExpanderThe maximum work outfit of the LN2 engine results from an isothermal blowup stroke. Achieving isothermal expansion provide be a challenge, because the fare of heat addition d emand 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. forget me drug expanders such as the Wankel may also be well suited. A secondary fluid could be circulated through the engine block to serving keep the cylinder walls as warm as possible. Multiple expansions and reheats can also be used although they require more than complicated machinery. HeatExchangerThe primary heat exchanger is a critical destiny of a LN2 automobile. Since ambient vaporizers are widely utilized in the cryogeny and LNG industries, there exists a substantial technology base. Unfortunately, portable cryogen vaporizers suitable for this youthful application are not readily available at this time. To compensate cryomobile operation over a wide range of weather conditions, the vaporizer should be capable of heating the LN2 at its maximum flow r ate 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 leave behind 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 somewhat 40% efficiency. Thus the heat exchanger system should be providentially designed to absorb at least 75 kW from the atmosphere when its temperature is only 0C.POWER CYCLEThere are some(prenominal) thermodynamic cycles available for utilizing the thermal emf of liquid nitrogen. These range from the Brayton cycle, to victimization two- and even three-fluid topping cycles, to employing a hydro deoxycytidine monophosphate-fueled boiler for superheating beyond atmospheric temperatures. The easiest to implement, however, and the whizz chosen for this study, is shown below. This system uses an open Rankine cycle. The states involved in the temperature entropy plat for the open rankine cycle is described below. 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. win 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 higher up 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 energ ies competitive with those of lead-acid batteries.ADVANTAGESLiquid nitrogen automobiles will have significant performance and environmental advantages over electric vehicles. A liquid nitrogen car with a 60-gallon armored combat vehicle 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 todays petrol 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.Compared to fossil fuelsThe process to manufacture liquid nitrogen in large quantities can be environmentally very friendly, even if fossil fuels are used to start the elect ric 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 minify urban air pollution as desired by current zero-emission vehicle mandat es.