Showing papers on "Combustion published in 1974"

Experimental and theoretical investigation of turbulent burning model for internal combustion engines

Abstract: A model for describing turbulent flame propagation in internal combustion engines is presented. An approximate analytic method for determining the equilibrium state of the burned gases is also presented. To verify the predictions of the model, experiments were carried out in a single-cylinder research engine at speeds from 1000-3200 rpm, spark advances from 30-110 deg btc and fuel-air equivalence ratios from 0.7-1.5. Simultaneous measurements of the cylinder pressure and the position of the flame front as a function of crank angle were made, and good agreement with the predictions of the model was obtained for all operating conditions.

Downhole recovery system

Abstract: The specification discloses a recovery process and system wherein hydrogen and oxygen are introduced into a vented pressure vessel, known as a gas generator, located at the bottom of a borehole, and ignited and burned to produce steam. The hydrogen and oxygen may be introduced either as a stoichiometric mixture or the combustible mixture may be hydrogen-rich. The gas generator comprises a cooling annulus surrounding a combustion and mixing zone for cooling the gas generator and the combustion products. Hydrogen or water may be supplied to the cooling annulus for cooling purposes. Remotely controlled valves are located downhole near the gas generator for positive control to the gas generator of the hydrogen and oxygen and of the water, if it is employed for cooling purposes. The well casing is sealed just above the gas generator by an inflatable packer. Provision is made for maintaining the desired hydrogen-oxygen ratio either by a hydrogen flow control slaved to a downhole thermocouple or by a special hydrogen-oxygen flow control employed in the event that ignition is carried out by a DC power supply located downhole. Although the preferred embodiment employs a fuel-oxidizer cooling fluid combination of hydrogen and oxygen or hydrogen, oxygen, and water, provision is made for employing other fuel-oxidizer-cooling fluid combinations.

Laser Raman Gas Diagnostics

Abstract: : Examining the use of Raman scattering as a gaseous systems probe, this volume emphasizes the application of laser Raman gas diagnostics to fluid mechanics and combustion measurements. Topics ranging from the basic physics and chemistry involved in scattering measurements to present and potential applications in flame systems, industrial process control, and the atmosphere are discussed. This book investigates important fluid mechanics problems for which Raman scattering can contribute new information and surveys efforts in the development of diagnostic capabilities designed to correspond to the needs of fluid mechanics. In addition, this work reports on significant nonthermal and nonchemical equilibrium problems and explores types of laser sources, spectral discrimination systems, and signal processing.

The Role of Energy-Releasing Kinetics in NOx Formation: Fuel-Lean, Jet-Stirred CO-Air Combustion

Abstract: Oxides of nitrogen concentrations, temperatures and mass flow rates near reactor blowout have been measured for chemically rate-limited, fuel-lean combustion of carbon monoxide with moist air in a jet-stirred reactor at 0.5 and 1 atmosphere. Comparisons with predictions obtained by modeling the jet-stirred reactor as a micromixed perfectly stirred reactor are used to examine the detailed influences of energy-releasing kinetic processes on NOx formation. Reaction radical intermediates and, in particular, oxygen atoms are shown to play a key role in this influence. For fuel-lean combustion, under conditions of intense turbulence and backmixing, super-equilibrium concentrations of oxygen atoms cause N2 O to act as an important intermediate leading to NOx formation. Measurements indicating the influence of finite mixing on experimental reactor performance and NOx emissions are presented as well.

Role of Binders in Solid Propellant Combustion

Abstract: : The objective of this program was to investigate and define the effects of inert binder properties on composite solid propellant burning rate. Experimental pyrolysis data were obtained for many binders of practical interest over a wide range of heating rates and pressures, in several environmental gases, with and without 10-percent ammonium perchlorate (AP) contained in the sample, and in some cases with catalysts. These data were used to extract kinetics constants from Arrhenius plots, and heat of decomposition. In addition, motion pictures were taken of the pyrolyzing surface and gas samples were extracted for analysis. Pyrolysis kinetics varied between binders, but were found to be independent of pressure, the presence of AP, and the presence of burn rate catalysts; however, a chlorine gas environment had a material effect upon the results. All of the binders exhibited molten, boiling surfaces mingled with char, to varying degrees; the amount of char increased with AP present, and in chlorine. Relevant data were input to the Derr-Beckstead-Price combustion model in order to associate binder properties with known binder effects on burning rate. Although the effects were predictable, they stemmed from properties other than pyrolysis kinetics; however, the binder data as applied to the model revealed possible deficiencies in the model, which are discussed. It appears that the approach of combustion tailoring by binder modification would have to involve the gas phase combustion processes rather than surface pyrolysis. Therefore, future work concerning the role of binder should be directed toward the gas phase.

Low emission combustion chamber

Abstract: A low emission combustion chamber in which vitiated products of combustion from a pilot burner are caused to swirl about the combustion chamber axis before fuel droplets are introduced into the vitiated, swirling combustion products for flash vaporization therein to produce a vaporized, swirling, vitiated fuel-air mixture so as to effect ignition lag until swirling combustion air can be mixed with the swirling mixture to molecularly premix the fuel and air and increase its oxygen content to reduce the ignition lag to effect autoignition at an equivalence ratio less than 1 so as to effect high-rate, lean burning in the primary combustion chamber.

Low-Temperature-Oxidation Reaction Kinetics and Effects on the In-Situ Combustion Process

Abstract: The kinetics of low-temperature oxidation (LTO) of crude oils in porous media was studied. The order of the reaction was dependent upon the crude but independent of the properties of the porous medium. The activation energy of the reaction was insensitive to the type of crude or porous medium and is in the neighborhood of 31,000 btu/lb mol. LTO reactions also were found to be in the kinetics- influenced region. The measured reaction rates for a 19.9$ API and a 27.1$ API crude indicated higher oxidation rates under similar reaction conditions for the higher API gravity crude. Thus, light crudes are more susceptible to partial oxidation at low temperatures because of their relatively high hydrogen content. Effect of partial oxidation of the crude on the in situ combustion process was studied by experimentally simulating the zones preceding the combustion front where temperatures and injection rates of a linear reservoir model were programed with time according to a predesigned schedule. Oxidation of the crude at temperatures below 400/sup 0/F had significant effects on the behavior of the crude oil-water system in the porous medium at elevated temperatures and on the fuel available for combustion. (22 refs.)

Combustion in an internal combustion engine

Abstract: A technique for increasing the efficiency, and for decreasing the exhaust emissions, of an internal combustion type engine in which substantially rf energy (e.g., 106 Hz to 1012 Hz) is generated and coupled to a combusting plasma airfuel mixture (preferably at a plasma frequency) so as to enhance both pre-combustion conditioning of the mixture and combustion reactions.

Process for producing carbon black

Abstract: There is disclosed herein a process for the production of oil furnace carbon blacks, which process is characterized by exceptionally high throughput, efficient use of heat, facile scale-up, high yields and the ability to produce high quality novel and desirable carbon blacks. The process involves the use of a staged reaction system whereby there is provided, seriatim, a combustion zone, a feedstock injection zone and a carbon forming zone.

Internal combustion exhaust catalytic reactor monitoring system

Abstract: To supervise operational effectiveness of catalytic reactors included in exhaust emission detoxification systems, an oxygen sensor is located downstream of the reactor to determine oxygen content in the exhaust gases from the internal combustion engine, the oxygen sensor comprising an ion conductive solid electrolyte forming an ion concentration chain and having catalytically inactive contacts, connected to a detection circuit which provides an output signal in dependence on a signal from the sensor, the output signal operating an alarm, or a transducer which interferes with proper engine operation to force the operator to have the reactor repaired. Preferably, two ion conductive chains are used, in a single sensor, or in two sensors, one being exposed to exhaust gases upstream of the catalytic reactor and the other downstream of the catalytic reactor, the output signals being provided to a differentially connected operational amplifier, to balance out extraneous influences.

Combustion method and apparatus

Abstract: A combustion method and apparatus for gas turbine engines employs a combustion process and combustion liner structure adapted to promote complete combustion of liquid hydrocarbon fuel and minimize undesired combustion products. Compressed primary air flows radially inward into a prechamber into which fuel is sprayed. Except during start-up, the air is heated. Normally, the air mixes with and evaporates the fuel and the mixture flows through a throat into a reaction chamber. The upstream end of the reaction chamber is bounded by a biconical annular wall, the inner radial portion of which diverges sharply and the outer radial portion of which diverges less sharply. The liner wall downstream of the throat defines the reaction zone and a dilution zone to which secondary air is admitted. The areas of both the primary and the secondary air entrances are variable to maintain a lean fuel-air ratio in the reaction zone throughout the operating regime. The swirl angle of the entering primary air is variable. In starting combustion, the air is admitted with a very considerable degree of swirl, causing recirculation from the reaction chamber into the prechamber to facilitate ignition and promote fuel vaporization and stable combustion with a cold engine. After light-off, the quantity of primary air increases along with the fuel, and the primary air swirl is reduced or terminated so that the flame front is blown out of the prechamber into the reaction zone and no combustion takes place in the prechamber in the operating regime.

Method and apparatus for turbine system combustor temperature

Abstract: A method and apparatus for operating a gas turbine system are disclosed utilizing an adiabatic combustion process, employing combustion of a pre-mixed carbonaceous fuel-air admixture in a combustion zone. The combustion and the combustion zone are maintained at an approximately constant temperature by selective control of the fuel-to-air ratio over a period of turbine operation during which the fuel demand or the combustion air temperature varies. Such combustion is conducted in the presence of an oxidation catalyst and the combustion zone including the catalyst is maintained at an approximately constant temperature. In a mode of operation which is preferred when conditions permit, such temperature is substantially above the instantaneous auto-ignition temperature of the fuel-air admixture but below a temperature that would result in any substantial formation of oxides of nitrogen. The resulting effluent is characterized by high thermal energy useful for generating power and may be low in atmospheric pollutants, including oxides of nitrogen.

Photographic and Performance Studies of Diesel Combustion With a Rapid Compression Machine

Abstract: Photographic and performance studies with a Rapid Compression Machine at the Massachusetts Institute of Technology have been used to develop insight into the role of mixing in diesel engine combustion. Combustion photographs and performance data were analyzed. The experiments simulate a single fuel spray in an open chember diesel engine with direct injection. The effects of droplet formation and evaporation on mixing are examined. It is concluded that mixing is controlled by the rate of entrainment of air by the fuel spray rather than the dynamics of single droplets. Experimental data on the geometry of a jet in a quiescent combustion chamber were compared with a two-phase jet model; a jet model based on empirical turbulent entrainment coefficients was developed to predict the motion of a fuel jet in a combustion chamber with swirl. Good agreement between theory and experiment was obtained. The fuel and air mixing rate was estimated from the jet models and compared with combustion rates measured in the Rapid Compression Machine.

Combined fuel vapor injector and igniter system for internal combustion engines

Abstract: A combined fuel vapor injector and igniter system for internal combustion engines and method of operating the engine therewith in which liquid fuel enters an injector-igniter device, is vaporized using the engine''s heat of combustion, and exits in vapor form into the engine combustion chamber where it mixes with air or an air-fuel mixture which has entered through an intake valve, or port, and the resulting air-fuel mixture is ignited. The system assures reliable ignition, so that engines may be run at leaner than stoichiometric air-fuel ratios to take advantage of increased fuel economy, and reduced emissions of the oxides of nitrogen, hydrocarbons and carbon monoxide. Power output equalization is attained between cylinders.

Gas turbine combustion chambers

Abstract: Combustion chamber comprising a first combustion zone opening into a wider second combustion zone into which the combustion air is admitted through a practically frontal air entry comprising obstacles which impart a coefficient of blocking of about 60% to 80% to it. The first zone is supplied with air and fuel in substantially stoichiometric proportion in idling. At the other running rates, a supplementary fuel flow is injected into the chamber and burns in the second zone in the wake of the obstacles.

Fluid bed coal gasification

Abstract: A process and apparatus for gasifying coal to produce carbon monoxide and hydrogen in which a first stream of coal is burned without bed formation in a combustion zone in the presence of water under oxidation conditions to produce gases containing carbon dioxide and steam. A second stream of coal is maintained as a fluid bed in a separate gasifier zone by upflowing carbon dioxide and steam from the combustion zone while being gasified under reducing conditions to produce carbon monoxide and hydrogen. Char produced in the fluid bed is elutriated overhead and material in the fluid bed is prevented from direct entry into the combustion zone. The ratio of carbonaceous material to ash in the char removed overhead is lower than the average ratio of carbonaceous material to ash in the solids in the fluid bed.

Heat exchanger utilizing adjoining fluidized beds

Abstract: A heat exchanger in which a substantially vertical partition divides a housing into at least two adjoining chambers each of which support a bed of particulate fuel material. Air is passed through the beds to promote the combustion of the fuel material and to maintain the chambers at predetermined temperatures. The fuel material in one of the chambers is relatively coarse while the fuel material in the other chamber is relatively fine with the chambers communicating to permit circulation of portions of the fuel between the chambers.

Device for converting calorific energy into mechanical energy

Abstract: An engine including a combustion chamber having connected thereto a combustion-air inlet duct in which a first restriction is incorporated, and a flue-gas return duct incorporating a second restriction connected to a part of the combustion air duct which is situated between the combustion chamber and the first restriction.

Fluid catalytic cracking process with substantially complete combustion of carbon monoxide during regeneration of catalyst

Abstract: An improved fluid catalytic cracking process providing improved product yield and selectivity employs a regenerated hydrocarbon conversion catalyst having improved activity and a low level of residual coke, desirably less than 0.05 wt. % on catalyst, obtained by burning coke from spent catalyst under balanced conditions supporting substantially complete combustion of carbon monoxide with provision for recovery of evolved heat by transfer directly to the catalyst particles particularly within a dilutephase zone in the regenerator vessel. Effluent gas from the regenerator may be discharged directly to the atmosphere with no discernible effect upon ambient air quality.

Combustion Response Function Measurements by the Rotating Valve Method

Abstract: A study has been conducted to evaluate the rotating valve method of measuring the combustion response of solid propellants to small amplitude pressure oscillations. The method is based on producing pressure oscillations in a small rocket motor by varying the area of a secondary exhaust nozzle in a periodic manner. This is accomplished by using a rotating valve as the secondary orifice. The valve apparatus operates concurrently with a primary nozzle which controls the steady-state pressure. The frequency of the oscillations is determined by the rotational speed of the valve. A theoretical analysis was conducted to relate the combustion response function to measurable ballistic properties of the combustion chamber. Assuming that the combustion chamber is small in comparison to the acoustic wavelength, the combustion response function can be calculated from the amplitude of the oscillating pressure and the phase angle between the oscillating pressure and oscillating nozzle area. Cold flow tests were conducted using nitrogen and helium to test the validity of the analysis. Excellent agreement was found between the measured and predicted amplitudes and phase angles. Combustion tests then were conducted using two aluminized propellant formulations and three nonaluminized formulations. There was excellent agreement between the T-burner and rotating valve tests conducted on the same batch of propellant. For two nonaluminized propellants, the comparisons were based on different batches of propellant. Differences in combustion response and variations in burning rate and characteristic exhaust velocity were observed for these two formulations. It was concluded that the rotating valve method is a valid substitute for the T-burner. Substantial reductions in the cost of characterizing propellants also were obtained using this new approach.

Method of liquid fuel injection, and to air blast atomizers

Abstract: An airblast atomozier which spreads liquid fuel into a continuous thin sheet, and exposes both sides of the sheet to the atomizing action of high velocity non-swirling air. The atomizer then injects the atomized fuel into a region of high turbulence and high shear formed by the meeting of two contra-rotating swirling air flows and in which region combustion occurs. This region is spaced from the atomizer a sufficient distance to permit full atomization of the fuel before it reaches such region. Also, the downstream end of the atomizer has no large transverse surfaces so exposed to the combustion process that significant deposits of combustion products can accumulate thereon.

Apparatus for processing molten metal

Abstract: A gas cleaning system for hearth furnaces having means for injecting process fluids below the level of molten metal and means for adjusting air intake by means of dampers in the furnace or the gas flow system or adjustable gaps between the furnace and the gas cleaning system. The furnace may be operated in the full or partial combustion mode wherein suitably located dampers control air flow to obtain the desired degree of combustion. Control means adjusts the damper or gap in the event normal air flow is disturbed. Provision is made in the system for measuring the calorific value of the off-gases and recovery of those off-gases having usable fuel capacity.

Fuel supply apparatus for internal combustion engines

Abstract: A fuel supply apparatus generates hydrogen and oxygen by electrolysis of water. There is provided an electrolytic cell which has a circular anode surrounded by a cathode with a porous membrane therebetween. The anode is fluted and the cathode is slotted to provide anode and cathode areas of substantially equal surface area. A pulsed electrical current is provided between the anode and cathode for efficient generation of hydrogen and oxygen. The electrolytic cell is equipped with a float, which detects the level of electrolyte within the cell, and water is added to the cell as needed to replace the water lost through the electrolysis process. The hydrogen and oxygen are collected in chambers which are an integral part of the electrolytic cell, and these two gases are supplied to a mixing chamber where they are mixed in the ratio of two parts hydrogen to one part oxygen. This mixture of hydrogen and oxygen flows to another mixing chamber wherein it is mixed with air from the atmosphere. The system is disclosed as being installed in an automobile, and a dual control system, which is actuated by the automobile throttle, first meters the hydrogen and oxygen mixture into the chamber wherein it is combined with air and then meters the combined mixture into the automobile engine. The heat of combustion of a pure hydrogen and oxygen mixture is greater than that of a gasoline and air mixture of comparable volume, and air is therefore mixed with the hydrogen and oxygen to produce a composite mixture which has a heat of combustion approximating that of a normal gas-air mixture. This composite mixture of air, hydrogen and oxygen then can be supplied directly to a conventional internal combustion engine without overheating and without creation of a vacuum in the system.