Showing papers on "Thermal efficiency published in 1980"

Combustion and pollution control system

Abstract: A controlled amount of a fluid (steam or water or a solution of water plus additives) is injected into an internal combustion engine to improve combustion, efficiency, and to reduce emissions. The amount of the fluid injected is controlled in response to engine need. The steam is generated by the heat produced by the engine. Combustion gas temperature is used to control the amount of steam produced by varying the fluid flow through one or more fixed or variable orifice control valves. The steam is injected in a piston engine to cool peak temperatures, to prevent detonation and pre-ignition, to smooth out hot spots, to prevent auto-ignition or dieseling, and to use the vapor energy in the expansion cycle to increase low speed torque and acceleration. The steam is used to cause full retard of the vacuum spark advance during acceleration at full load from low speed, and a large amount of steam is injected at this point in the cycle to prevent pre-ignition and detonation. Ultrasonic energy is added to the injected steam to produce better mixing and distribution. Hydrogen is also injected to permit better combustion with higher amounts of air. The hydrogen is produced by the interaction of a catalyst on the steam and fuel hydrocarbons and ultrasonic energy. At times exhaust gas and other additives, such as hydrogen peroxide, methyl alcohol and ammonia are injected.

Coefficient of performance for finite speed heat pump

Abstract: This paper gives the coefficient of performance for a heat pump operated at minimum input power for given output heat power.

Power cycles based upon cyclical hydriding and dehydriding of a material

Abstract: Improved power cycles for improving the production of power and refrigeration and for conserving thermal energy, utilizing as a common basic characteristic, a hydride-dehydride-hydrogen power cycle in which hydrogen is reversibly combined with a hydride-forming material at a relatively low temperature and pressure, the hydrided material is then heated at constant volume to chemically compress the hydrogen, and finally the material is dehydrided by further heating the material to release hydrogen gas at relatively high pressure and temperature. The pressurized high temperature hydrogen gas as thus developed is used in various ways for producing power and refrigeration, including functioning as a low temperature heat sink for certain auxiliary or ancillary power cycles, prior to recycling the hydrogen gas for reuse in the described hydride-dehydride-hydrogen cycle.

Adaptive charge forming system for controlling the air/fuel mixture supplied to an internal combustion engine

Abstract: An adaptive charge forming system for an internal combustion engine is disclosed which monitors a parameter of engine combustion efficiency, such as power output, and derives a signal indicating the direction and amplitude of power change. The fuel mixture control system responds to changes in power output, regardless of their source, to maintain the engine air/fuel ratio in a preferred region. In a preferred embodiment, engine crankshaft angular acceleration is monitored to maintain the air/fuel mixture at the lean limit. A stepping motor is used to control a value for bleeding additional air into the charge; a clock provides steady pulses to the motor, tending to lean the mixture, while enrichment is effected upon the detection of each weak combustion event. The clock frequency thus sets the equilibrium rate of weak combustion events, defining the optimal mixture to be supplied to the engine.

Optimal configuration of an irreversible heat engine with fixed compression ratio

Abstract: The cycle that maximizes the average power output of a class of irreversible heat engines has been obtained using optimal control theory. This class of heat engines is distinguished by being endoreversible, having a fixed compression ratio and being irreversible because of linear heat conduction. The optimal cycle is found to have eight branches including two fixed-volume branches, two isothermal branches, and two maximum-power branches. Maximum-power branches are defined and discussed in detail. It is shown that the maximum-power cycle contains no adiabatic branches. Two special limits are analyzed in detail, the Curzon-Ahlborn limit and the large-compression-ratio limit. The fixed-compression-ratio constraint and the periodicity of the engine require special attention which lends this problem some purely mathematical interest.

Simulation studies of the effects of turbocharging and reduced heat transfer on spark-ignition engine operation

Abstract: A computer simulation of the four-stroke spark-ignition engine cycle has been used to examine the effects of turbocharging and reduced heat transfer on engine performance, efficiency and NOx emissions. The simulation computes the flows into and out of the engine, calculates the changes in thermodynamic properties and composition of the unburned and burned gas mixtures within the cylinder through the engine cycle due to work, heat and mass transfers, and follows the kinetics of No formation and decomposition in the burned gas. The combustion process is specified as an input to the program through use of a normalized rate of mass burning profile. From this information, the simulation computes engine power, fuel consumption and NOx emissions.

Underfire air and steam system and incinerating process for a controlled starved-air incinerator

Abstract: An underfire system for a controlled starved-air incinerator and incinerating process which minimizes high localized temperatures in the main combustion chamber to lessen clinker formation and vaporization of inorganics for minimizing the particulate emission rate and which maximizes conversion of the fixed carbon portion of the waste materials into volatile matter for maximizing the thermal efficiency of the incinerator. The underfire system supplies air at less-than-stoichiometric requirements which creates an exothermic reaction between some of the fixed carbon in the waste material and the oxygen in the air to produce volatile carbon dioxide. In addition, steam is supplied to the burning waste materials, preferably alternately with the air supply, for creating an endothermic "water-gas reaction" between additional fixed carbon in the waste material and the steam to produce volatile carbon monoxide and hydrogen gas and for absorbing undesired heat from the exothermic reaction.

Thermodynamics in finite time: A chemically driven engine

Abstract: The methods of finite time thermodynamics are applied to processes whose relaxation parameters are chemical rate coefficients within the working fluid. The direct optimization formalism used previously for heat engines with friction and finite heat transfer rates—termed the tricycle method—is extended to heat engines driven by exothermic reactions. The model is a flow reactor coupled by a heat exchanger to an engine. Conditions are established for the achievement of maximum power from such a system. Emphasis is on how the chemical kinetics control the finite‐time thermodynamic extrema; first order, first order reversible, and second order reaction kinetics are analyzed. For the types of reactions considered here, there is always a finite positive flow rate in the reactor that yields maximum engine power. Maximum fuel efficiency is always attained in these systems at the uninteresting limit of zero flow rate.

Energy efficient engine

Abstract: The feasibility of meeting or closely approaching the emissions goals established for the Energy Efficient Engine (E3) Project with an advanced design, single annular combustor was determined. A total of nine sector combustor configurations and one full-annular-combustor configuration were evaluated. Acceptable levels of carbon monoxide and hydrocarbon emissions were obtained with several of the sector combustor configurations tested, and several of the configurations tested demonstrated reduced levels of nitrogen oxides compared to conventional, single annular designs. None of the configurations tested demonstrated nitrogen oxide emission levels that meet the goal of the E3 Project.

Device for recovering heat energy in a supercharged internal-combustion engine

Abstract: A method and a device for recovering energy from a supercharged internal-combustion engine by producing a complementary amount of energy from a system operating on a Rankine cycle, includes preheating the working fluid used in the Rankine cycle through heat exchange with the air issuing from the compressor of the supercharger of the internal-combustion engine

Internal combustion engine with Rankine bottoming cycle

Abstract: An internal combustion engine with a Rankine bottoming cycle including an internal combustion engine (10) with an exhaust (12) for exhausting combustion gases. Included is an expander (24) having a mechanical output (26) for performing useful work and a boiler (18). Liquid is supplied in a line (20) to the boiler to be vaporized therein and the vaporized liquid is supplied by a line (22) to the turbine (24) to drive the same. Heat for vaporizing the liquid in the boiler (18) is obtained from the exhaust (12) on a line (62). The exhaust gases are further expanded in an expander (72) thereby providing additional useful work.

Reciprocating heat engine

Abstract: A reciprocating external combustion engine wherein energy is supplied to a working end space of the engine by direct injection into the cylinder of liquid water at a high temperature and pressure. The water acts as a heat-transfer medium. Some of the liquid water spontaneously vaporizes on injection, driving the piston. Liquid water is exhausted from the cylinder and recycled to an external heat exchanger for reheating prior to reinjection. The engine is capable of a thermal efficiency greater than that of the Rankine cycle.

Jet engine augmentor operation at high altitudes

Abstract: In the operation of an air atomized jet engine augmentor oil burner, the herein disclosed improvement typically comprises a means for modulating the fuel-air ratio of the wake combustion in the jet engine augmentor according to ambient pressures and densities of the supplied air to that ratio which will sustain the highest wake combustion thermal efficiency, and in the process to vaporize and ignite the fuel-air mixture therein instantly and completely into an intense and turbulent flame spread. My method of doing this is to create unusually intense combustion activities resulting from the energy input of controlled high energy pulsed laser beam or beams directed into the forward area of the recirculation zone of the augmentor to ignite and explode fuel droplets therein; the said combustion activities to be of sufficient power and turbulence to change the normal aerodynamics of the flame-holder aerosol flower in such a manner as to alter their reaction kinetics favorably and thereby cause a bypass of a predetermined portion of the normal fuel drop-ins by adjusting the frequency of the laser beam pulses directed into the said recirculation zone. The procedure here is to measure the density (pressure) of the ambient air and convert this into corresponding predetermined laser pulse frequencies to control the amount of fuel captured in the recirculation zone and thereby attain the wake combustion fuel-air ratio desired for the operating altitude.

Apparatus for improving the fuel efficiency of a gas turbine engine

Abstract: An energy recovery system is provided for an aircraft gas turbine engine of the type in which some of the pneumatic energy developed by the engine is made available to support systems such as an environmental control system. In one such energy recovery system, some of the pneumatic energy made available to but not utilized by the support system is utilized to heat the engine fuel immediately prior to the consumption of the fuel by the engine. Some of the recovered energy may also be utilized to heat the fuel in the fuel tanks. Provision is made for multi-engine applications wherein energy recovered from one engine may be utilized by another one of the engines or systems associated therewith.

Waste heat recovery system for an internal combustion engine

Abstract: A method and apparatus for recovering and utilizing waste heat from the exhaust and coolant of an internal combustion engine. The waste heat recovery system uses two separate and closed circuits of working fluid with one circuit being heated by the exhaust gases and the other being heated by the engine coolant. In the preferred embodiment, two different working fluids are used and each circuit is designed to operate at temperatures and pressures most efficient for that particular working fluid and the heat available from the exhaust in one case and the coolant in the other case. A heat exchanger is provided between the two circuits for increased efficiency and a heat reservoir of melted salt is built into the exhaust heated circuit to minimize surges in the system and to provide reserve power during high performance demands. In the preferred embodiment, the work produced by the exhaust heated circuit is sequentially added to the power output of the engine and vane expanders rather than turbines are used for a more direct and efficient coupling of the available work from the recovered waste heat to the power output of the engine. A manner is also disclosed in which the basic flow pattern of the preferred embodiment can be adapted to operate with a single working fluid if desired.

Improvement of alcohol engine performance by flash boiling injection

Abstract: A fuel supply method called "flash boiling injection" has been developed to overcome the problems associated with alcohol fuel use. In flash boiling, a fluid boils when the pressure around it falls below the saturation pressure. By applying this principle, the spray droplet size can be made small, the spray angle large, and the spray travel short to improve thermal efficiency and to reduce exhaust emission of unburnt alcohol. Flash boiling injection can be applied to both spark ignited and diesel engines. The technique has been successfully applied to the unthrottled operation of an open-chamber, spark ignited engine to improve thermal efficiency at partial load.

Algorithm for calculating turbine cooling flow and the resulting decrease in turbine efficiency

Abstract: An algorithm is presented for calculating both the quantity of compressor bleed flow required to cool the turbine and the decrease in turbine efficiency caused by the injection of cooling air into the gas stream. The algorithm, which is intended for an axial flow, air routine in a properly written thermodynamic cycle code. Ten different cooling configurations are available for each row of cooled airfoils in the turbine. Results from the algorithm are substantiated by comparison with flows predicted by major engine manufacturers for given bulk metal temperatures and given cooling configurations. A list of definitions for the terms in the subroutine is presented.

Multi-pass helical coil thermal fluid heater

Abstract: This invention relates to a multi-pass helical coil thermal fluid heater of improved thermal efficiency. The thermal fluid is heated while being circulated within concentric helical coils of the heater which are arranged in such a manner to improve overall thermal efficiency and simplify construction. Provision is also made for preheating of the thermal fluid and the heater combustion air to further improve thermal efficiency.

Rotary heat engine

Abstract: A rotary external combustion engine wherein energy is supplied to a working space of the engine by direct injection into the stator of liquid water at a high temperature and pressure. The water acts as a heat-transfer medium. Some of the liquid water spontaneously vaporizes on injection, during the rotor. Liquid water is exhausted from the working space and recycled to an external heat exchanger for reheating prior to reinjection. The engine is capable of a thermal efficiency greater than that of the Rankine cycle.

The Combined Reheat Gas Turbine/Steam Turbine Cycle: Part I—A Critical Analysis of the Combined Reheat Gas Turbine/Steam Turbine Cycle

Abstract: The reheat gas turbine cycle combined with the steam turbine Rankine cycle holds new promise of appreciably increasing power plant thermal efficiency. Apparently the cycle has been overlooked and thus neglected through the years. Research and development is being directed towards other gas turbine areas because of the world energy crunch; and in order to focus needed technical attention to the reheat cycle, this paper is presented, using logic and practical background of heat recovery boilers, steam turbines, gas turbines and the process industry. A critical analysis is presented establishing parameters of efficiency, cycle pressure ratio, firing temperature and output. Using the data developed, an analysis of an actual gas generator, the second generation LM5000, is applied with unique approaches to show that an overall 50 percent efficiency power plant can be developed using today’s known techniques and established base-load firing temperatures.

High thermal efficiency power plant and operating method therefor

Abstract: A method of performing work and an apparatus for performing the method utilizing the following thermodynamic cycle. Ambient air is isothermally compressed to a predetermined degree (A-B) and then heat is added to the air at constant pressure (B-C). This is followed by isentropic compression (C-D) which in turn is followed by heat addition at constant volume (D-E). Thereafter follows isentropic expansion (E-F-H-G) then finally heat recovery (G-A). The recovered heat (G-A) is preferably utilized for the initial heat addition (B-C).

Microwave actuated steam generator

Abstract: An apparatus and method of using the same in which microwave energy transforms water in the form of finely divided droplets having a large aggregate surface area into pressurized steam. The method of the present invention has a high thermal and electrical efficiency, as the microwave energy impinges directly on the water droplets, and there is no loss of heat by conduction or convection.