967 results about "Fuel injection" patented technology

The invention discloses a dual-fuel engine combustion control method based on hydrogen-ammonia energy ratio and gas distribution overlap angle regulation and control, which comprises the following steps: 1) fuel ratio control: acquiring current operation state parameters of an engine, determining a target AER according to preset mapping, regulating ammonia gas supply quantity and hydrogen supply quantity to enable the actual AER to reach the target AER, and controlling the fuel ratio; the AER is adaptively set according to engine load and combustion stability conditions; 2) valve timing control: adjusting the opening time of an intake valve or the closing time of an exhaust valve through a variable valve timing mechanism so as to change a valve timing overlap angle VOA, wherein the VOA is set to be a negative value, a small overlap angle or a positive overlap angle according to the working condition of an engine; (3) injection time sequence optimization is conducted, specifically, the injection time of ammonia gas and the in-cylinder direct injection time of hydrogen are controlled respectively, and coordinated optimization of a fuel injection strategy and valve timing is achieved; and 4) closed-loop steady-state control: monitoring a combustion state and an emission index in real time, comparing the combustion state and the emission index with a threshold value to serve as a feedback signal, and correcting the target AER and VOA settings in time. According to the dual-fuel engine combustion control method based on regulation and control of the hydrogen-ammonia energy ratio and the gas distribution overlapping angle, the energy ratio of hydrogen fuel and ammonia fuel and the overlapping opening angle of an intake valve and an exhaust valve are dynamically adjusted under different working conditions, so that the combustion reaction rate and temperature are coordinated, and the stable and efficient combustion process is achieved; and harmful emissions of NOx, unburned ammonia and the like are obviously reduced.

The invention relates to the technical field of vehicles, and discloses an engine intelligent layered thermal management system and method based on multivariable predictive control, and the system comprises a thermal management execution module, an information sensing module and an intelligent control module; the information sensing module is used for collecting real-time information and sending the real-time information to the intelligent control module; the information sensing module comprises a plurality of sensors and a communication interface, the plurality of sensors at least cover a temperature sensor, a pressure sensor and a flow sensor, and the communication interface is used for obtaining engine torque, rotating speed, fuel injection amount, boost pressure and vehicle speed information; the intelligent control module receives the real-time information sent by the information sensing module, performs thermal load prediction and multi-target optimization calculation to obtain an optimal control sequence, and sends the optimal control sequence to the thermal management execution module; and the thermal management execution module receives the optimal control sequence and calls an execution element to execute a thermal management action.

A fuel pre-heating component in a gas turbine engine includes a component housing extending around a central axis from a first end to a second end, wherein the component housing includes walls that define an inner chamber, a heating element positioned inside the inner chamber, and a plurality of internal fuel channels disposed within the component housing and configured to be heated by the heating element.

The invention relates to the technical field of engine control, in particular to an engine combustion control method, device and system based on double oil sprayers and a computer program product. Comprising the steps that when an engine enters a lean-burn working condition and meets a self-learning condition, self-learning of the injection starting angle and the excess air coefficient of an auxiliary oil injector is conducted; ignition advance angle self-learning of the auxiliary fuel injector is carried out; and fuel injection control over the auxiliary fuel injector is conducted on the basis of the injection starting angle, the excess air coefficient and the ignition advance angle obtained through self-learning. And when refined fuel oil control is carried out to achieve the optimal fuel consumption of the engine, the lowest NOx emission requirement under the lean-burn working condition of the engine is met.

The invention provides a turbine engine starting processing method and system and a storage medium, and the method comprises the steps: obtaining the rotating speed of a high-pressure rotor, and dividing the high-pressure rotor into a cold operation stage, an ignition stage, an acceleration stage and a slow transition stage which are executed in sequence according to the rotating speed of the high-pressure rotor; a corresponding self-adaptive control process is executed in each stage of the ignition stage, the acceleration stage and the slow transition stage, the self-adaptive control process comprises the steps that environment parameters and stage identification are obtained, and the environment parameters comprise the environment temperature, the flight height and the flight Mach number; processing the environment parameters by using the comprehensive correction logic to obtain a comprehensive environment correction coefficient; determining a target fuel control quantity based on the stage identifier and the comprehensive environment correction coefficient; target fuel injection pressure and target ignition parameters are determined based on the stage identifier, the environment temperature and the flight height; and starting control is executed based on the target fuel control quantity, the target fuel injection pressure and the target ignition parameters. The starting success rate and reliability of the engine can be improved.

The invention discloses a combustion chamber fuel injection and oil-gas mixing system suitable for a low-temperature environment, and belongs to the field of combustion chambers of gas turbines, the combustion chamber fuel injection and oil-gas mixing system comprises a flame tube, a centrifugal nozzle and a two-stage cyclone which are coaxially arranged, after fuel is atomized through the centrifugal nozzle and enters, the fuel is further atomized through rotational flow of an inner ring of the two-stage cyclone and enters the flame tube, and the fuel is injected into the combustion chamber through the centrifugal nozzle. External high-pressure air is swirled through the outer ring of the two-stage swirler to form swirling air, and internal fuel spray is crushed, atomized and mixed; a venturi tube is arranged at the end, close to the flame tube, of the inner ring of the two-stage cyclone, vortex generators are evenly arranged on the inner wall of the expansion section of the venturi tube in the circumferential direction, and oil mist with the small and even particle size is formed after the atomized mist is acted. Through multi-stage rotational flow, oil mist with fine and uniform granularity is formed, the atomization effect is optimized, and the fuel oil atomization quality and combustion stability in a low-temperature environment are improved.

A fuel nozzle for a turbine engine. The fuel nozzle has a premixer body, vortex generator, air injection orifice, and fuel injection orifice. The premixer body defines a primary flow path. The air injection orifice is provided in the premixer body and located downstream of the vortex generator. The fuel injection orifice is provided in the premixer body and opens into the primary flow path.

The invention provides a separation control method and device and a storage medium. The method comprises the steps that a gear shifting request sent by a gearbox control unit is received; the current fuel injection amount is detected; if it is detected that the current fuel injection amount is smaller than the preset fuel injection amount, the current remaining fuel amount and the current engine rotating speed are obtained; based on the current residual fuel quantity and the current engine rotating speed, the target moment is determined, and the target moment is the moment when the engine torque is reduced to the first preset engine torque; and the target interaction information is sent to the gearbox control unit, the target interaction information comprises the target moment, and the target moment is used for the gearbox control unit to control the clutch to be separated. According to the embodiment of the invention, the target moment is determined through the current residual fuel quantity and the current engine rotating speed, so that the problem of improper separation time caused by clutch separation based on the output torque under the condition that the output torque is inaccurate is avoided, and the accuracy of the clutch separation time is improved.

The application discloses a fuel injection control method and device, electronic equipment and storage medium. The fuel injection control method comprises the following steps: after the accelerator pedal is stepped on, determining the engine torque demand according to the current working state of the engine and the stepping amount of the accelerator pedal, and determining the required intake air amount and the required fuel amount of the engine according to the engine torque demand; determining the current throttle opening of the engine according to the required intake air amount, and after the current fuel injection pulse width of the fuel injector is determined according to the required fuel amount, controlling the throttle valve to hit the target position corresponding to the current throttle opening, and controlling the fuel injector to open to the current fuel injection pulse width; acquiring the current fuel injection rail pressure, and determining the fuel injection mass flow of the engine by querying the fuel injection mass flow calculation MAP according to the current fuel injection pulse width and the current fuel injection rail pressure; and inputting the fuel injection mass flow into the engine model to output the current air-fuel ratio. The application realizes real-time adjustment of the fuel injection mass flow.

An exhaust gas recirculation mixer according to certain embodiments includes a chamber through which a first fluid is operable to flow in a downstream direction toward a mixing passage. The chamber is fluidically connected with the mixing passage via a first nozzle, and the mixing passage extends along a longitudinal axis defining the downstream direction and an upstream direction opposite the downstream direction. The exhaust gas recirculation mixer further includes a second nozzle and a fuel nozzle. The second nozzle extends into the mixing passage and is configured to direct a second fluid toward the mixing passage. The second nozzle comprises a second nozzle outlet portion circumferentially surrounded by the first nozzle. The fuel nozzle comprises a fuel nozzle outlet portion configured to inject fuel into the chamber in a fuel injection direction, and the fuel nozzle outlet portion is positioned upstream of the first nozzle.

The invention discloses an engine multi-vehicle-type adaptive NVH quality optimization method and system, and belongs to the technical field of automobile engine debugge.The method comprises the steps that after an engine is installed on a to-be-adapted vehicle, vehicle working condition data are collected in real time, the vehicle working condition data comprises a vehicle speed, an accelerator opening degree, an engine rotating speed, a gear, a hydraulic torque converter locking state and an engine oil temperature signal; the vehicle working condition data is compared with the working condition of the engine noise sensitive working condition, and whether the engine noise sensitive working condition is entered or not is recognized; when the engine has the noise sensitive working condition, an NVH control strategy embedded in an engine electronic control unit is activated; the NVH control strategy comprises adjustment of an engine ignition angle and oil injection parameters; the engine is controlled according to the ignition angle optimization control instruction and the oil injection parameter optimization instruction; and when the vehicle runs out of the working condition of the noise sensitive working condition of the engine or gear shifting is completed, the conventional combustion control logic is recovered. And the rising rate of the pressure in the cylinder is effectively reduced, so that the structural knocking noise within the range of 150-600Hz is inhibited.

The invention relates to an intelligent valve terminal control method and system for electronic injection of an aero-engine, and the method comprises the steps: obtaining multi-source state data in the operation of the engine, and carrying out the preprocessing to form a high-dimensional time sequence feature vector; a deep learning inference model is utilized to accurately identify a current working condition and predict a future evolution trend; generating an optimal fuel injection strategy based on a model predictive control and reinforcement learning mixed strategy; on-line self-adaptive correction is carried out by monitoring a comparison result of an actual response and an expected output, and an optimization instruction sequence is generated; and finally, converting the signal into a multi-channel synchronous pulse width modulation driving signal, and accurately controlling the coordinated action of a plurality of fuel injection valves. Intelligent and fine control over fuel injection is achieved, the combustion efficiency, the dynamic response speed and the operation stability of the engine are effectively improved, meanwhile, emission is reduced through multi-target optimization, and the problems that in the prior art, control lags behind, multi-valve cooperation precision is insufficient, and working condition adaptability is poor are solved.

The invention relates to cleaning equipment for a fuel oil injection pipe, the cleaning equipment comprises a cleaning table, a cleaning cavity is formed in the middle position of the top of the cleaning table, and supporting frames are installed at the tops of the two ends of the cleaning table. A first electric telescopic rod in the cleaning assembly drives a first cleaning brush and a second cleaning brush to synchronously brush the inner wall and the outer wall of the fuel oil injection pipe body, and a movable pipe in the flushing assembly is matched to drive a nozzle to flush the fuel oil injection pipe body, so that oil stains and impurities are effectively removed; and a heating rod, an upper heating cover and a lower heating cover in the drying assembly are combined to efficiently dry the cleaned fuel injection oil pipe body, it is ensured that the interior of the oil pipe is dry and free of residues, and secondary pollution is avoided.

The invention relates to the technical field of automobile superchargers, and particularly discloses a turbocharger overspeed protection system which is characterized in that an air mass flow meter is connected to the air inlet end of an air compressor, a turbine is connected to the exhaust end of an engine, and the turbine is connected with the air compressor through a transmission shaft; the waste gas bypass mechanism is arranged at the air inlet end and the exhaust end of the turbine in parallel. The rotating speed sensor is used for detecting the rotating speed of the transmission shaft. Based on a safety overspeed area range preset by an electronic control unit, the fuel injection quantity of an engine and the opening degree of a waste gas bypass mechanism are dynamically adjusted according to data parameters fed back by a first detection unit, an air mass flow meter and a rotating speed sensor; namely, the exhaust state of the engine is actively intervened by regulating and controlling the oil injection quantity and precisely distributing waste gas, so that the energy for driving the turbine is indirectly controlled, the rotating speed of the turbocharger is always within a safe set range, and the running reliability and stability of the turbocharger are improved.

The invention discloses an aircraft high-altitude operation data calibration method based on a ground test, and the method comprises the following steps: S1, simulating all altitude environments, and selecting different working conditions; s2, calibrating operation data under different altitude environments and different working conditions; wherein in the step S2, the operation data comprises the fuel injection quantity, when the fuel injection quantity is calibrated, the working condition is selected, the optimal fuel injection quantity is set as an initial value under the 0-altitude environment, then adjustment is conducted on the basis of the initial value, and the fuel injection quantity under the same working condition at all the altitudes is determined according to the change condition of the aircraft power. The calibration process is relatively simple, the adjustment basis is reliable, the adjustment efficiency is high, the result is reliable, and the high-altitude flight reliability of the aircraft can be ensured.

The invention discloses a hydrogen injection control method of a hydrogen engine and related equipment, relates to the field of fuel injection and control of the hydrogen engine, and mainly aims to solve the problem of insufficient control precision of hydrogen injection control of the existing hydrogen engine. The method comprises the steps that the initial adjustment hydrogen injection amount is calculated based on operation condition data of an engine; introducing a short-term correction coefficient and a long-term correction coefficient to compensate the initial adjustment hydrogen injection amount so as to determine a target hydrogen injection amount; and determining a hydrogen spraying control instruction based on the target hydrogen spraying amount and the density correction coefficient. The method is used for the hydrogen injection control process of the hydrogen engine.

The invention relates to a cooperative control method and system for lean-burn emission of a marine low-zero carbon fuel engine. The method comprises the steps that real-time in-cylinder pressure and temperature data are collected, and an in-cylinder pressure curve and an in-cylinder temperature curve are obtained through time sequence alignment, filtering denoising and interpolation fitting processing; extracting time sequence data based on the curve, calculating average effective pressure and peak temperature in a cylinder to determine a current load interval, and marking a risk tag sequence; calculating the generation rate of the nitrogen oxides and the particulate matters by matching with reaction condition parameters, and extracting reverse variation characteristics to obtain strong mutual exclusion correlation of the nitrogen oxides and the particulate matters; and based on the associated starting model, predicting and controlling the output oil injection quantity and the air inflow adjusting quantity, calculating the transient time sequence lag quantity through a dynamic lag model, and after superposition, calibrating through a combustion phase matching algorithm to generate an oil injection timing and air inlet valve opening control instruction after transient adjustment. The method is adaptive to the combustion characteristics of low-zero-carbon fuel, emission contradictions are accurately captured, transient emission peak values are avoided, and multi-pollutant collaborative control is achieved.

A ship deployment and refueling joint optimization method considering multiple uncertainties comprises the steps that firstly, a nonlinear mixed integer programming deterministic model with the total cost minimization as the target is constructed, then random oil price and berthing time are introduced, a robust optimization model containing an uncertainty set is constructed, and the nonlinear mixed integer programming deterministic model and the robust optimization model are integrated to form a two-stage robust optimization model; iterative solution is carried out through a Benders decomposition algorithm with embedded branches and delimits, so that a robust optimal ship deployment scheme and a fuel oil filling strategy are obtained; according to the method, an integrated joint decision framework is constructed, ship deployment and fuel oil management are optimized in a unified mathematical model at the same time to capture and utilize the internal relation between different decisions, potential huge cost brought by separated decision is avoided, the uncertainty influence of oil price and port berthing time is fully considered, and the method has the advantages of being high in reliability and high in reliability. Therefore, the decision has a good hedging risk characteristic, the scientificity and economy of the decision are fundamentally improved, and the comprehensive cost of operation is effectively reduced.

The present application relates to the technical field of engine, and discloses a combustion system, a gas engine and a combustion system design method, a second fuel injection hole sprays an oil jet to ignite a part of natural gas jets on the same side of the second fuel injection hole, and under the action of a vortex in a combustion chamber, with the second fuel injection hole continuously spraying the oil jet, a flame formed by the oil jet igniting the natural gas jets gradually becomes longer along the vortex direction, so that the oil jet sprayed by the second fuel injection hole ignites the natural gas jets on the side of the natural gas injector opposite to the fuel injector; the oil jet sprayed by the first fuel injection hole ignites the remaining natural gas jets, so that the oil jets sprayed by the fuel injector on both sides of a reference line can achieve the maximum ignition effect, all the natural gas jets are ignited by using the least oil jet, the ignition effect of igniting the natural gas by using the fuel is improved, the thermal efficiency is higher, and the emission is lower.

The invention discloses a fuel injection method and device of an engine, a vehicle and a storage medium, a cylinder cover of the engine is provided with a fuel injector, a glow plug is arranged below an air inlet channel, the fuel injector is configured to inject fuel into a combustion chamber of the engine, and the glow plug is configured to heat the combustion chamber of the engine. The method comprises the steps that under the condition that an engine starting instruction is received, the cooling water temperature of an engine is obtained; under the condition that the temperature of the cooling water is smaller than or equal to a first preset temperature threshold value, the glow plug is controlled for heating; and under the condition that the temperature of the glow plug reaches the second preset temperature threshold value, the motor of the vehicle is controlled to drag the engine to rotate at the preset rotating speed, and the fuel injector is controlled to conduct single-time injection into the combustion chamber in the later period of the compression stroke. According to the fuel injection method, the problem that single-fuel cold start of the methanol engine is difficult in cold weather can be solved, the success rate of cold start of the engine is increased, and the cost can be reduced.

The invention discloses a cooperative control method for the air-fuel ratio, the injection opportunity and the cooling liquid temperature of a hydrogen fuel engine. The cooperative control method comprises the steps that S1, operation condition parameters and combustion state parameters of the hydrogen fuel engine are monitored; s2, based on the operation condition parameters, adaptively determining a target air-fuel ratio, a fuel injection opportunity and a cooling liquid temperature through a preset control strategy; s3, the combustion state and the engine operation condition are evaluated in real time through a closed-loop feedback control system, and the following cooperative adjustment is executed: the hydrogen supply amount is adjusted to maintain the target air-fuel ratio; the hydrogen injection time is adjusted, and the combustion phase is optimized. According to the cooperative control method for the air-fuel ratio, the injection opportunity and the cooling liquid temperature in the hydrogen fuel engine, the target air-fuel ratio, the hydrogen fuel injection opportunity and the engine cooling liquid temperature are comprehensively adjusted under a closed-loop feedback control framework, optimal control over the combustion process under different working conditions is achieved, and therefore the braking heat efficiency of the engine is improved, and the service life of the engine is prolonged. And pollutant emission is reduced, knocking is restrained, and the application requirement for efficient cleaning of the engine is met.

The invention discloses a fuel injection control method, device and equipment and a medium. The method comprises the steps that the injection back pressure during fuel injection of an engine is determined according to working condition parameters of the engine; the actual injection pressure is determined according to the injection demand pressure and the injection back pressure during fuel injection of the engine; according to the method, by introducing a dynamic compensation mechanism of the injection back pressure, the effective injection pressure difference can be accurately reflected, the control precision and the system robustness under the working condition of the small oil amount are remarkably improved, and the control precision and the system robustness under the working condition of the small oil amount are improved. And in an engine platform upgrading or multi-mode operation scene, whole machine rack calibration does not need to be carried out again, the development cost is greatly reduced, and the adaptability and engineering efficiency of fuel injection control are improved.

The application discloses a hybrid vehicle starting control method and device and a hybrid vehicle. The method comprises the following steps: obtaining preset starting parameters when a motor reverse drives an engine, wherein the preset starting parameters comprise a preset motor reverse driving speed, a preset motor reverse driving engine exit rotating speed and a preset engine starting fuel injection amount; starting the motor reverse driving engine function according to the preset starting parameters, and determining an engine starting state; when the engine starting is successful, the starting is completed and the method is exited; when the engine starting fails, the method enters a motor reverse driving self-learning mode, and starting adjustment parameters are determined according to the preset starting parameters; the motor reverse driving engine function is started again according to the starting adjustment parameters until the engine starting is successful. When the motor reverse driving engine fails, the motor reverse driving self-learning mode is entered, starting adjustment parameters are generated, and the starting success rate of the motor reverse driving engine is ensured.

A method (100) for adjusting the timing of fuel injection into a combustion chamber (24) of a compression ignition engine (12), the method (100) comprising: Detect (102), via an electronic control (60), a request to generate zero torque by the motor; Switching off (104), via the electronic control (60), of the fuel supply to the combustion chamber (24) during the detected requirement to generate a torque of zero; Issue (106), via the electronic control (60), a command to inject a test quantity of fuel into the combustion chamber (24) while the detected requirement to generate zero torque exists; Assess (108), via the electronic control (60), a time delay (74) between the command given to inject the test fuel quantity and the start of the injection of the test fuel quantity; Determine (110), via the electronic control (60), a compensation for the assessed time delay (74); Detect (116), via the electronic control (60), a request to generate a positive torque by the motor and commands (118), via the electronic control (60), a shift in the timing of fuel injection into the combustion chamber (24) by the determined compensation during positive torque generation by the engine.

A closed-loop automatic control system for ship speed and a method are provided, including the following steps: obtaining feedback information through a detection feedback module, and generating a final effective main engine speed order nE* through an outer-loop control module; through the middle-loop control module, the main engine speed order nE* is compared with the main engine speed n by the speed deviation Δn, which uses PID and other control algorithms, the final effective main engine fuel quantity order LS* is generated; through the inner-loop control module, generating the fuel quantity deviation ΔL between the main engine fuel quantity order LS* and fuel quantity feedback signal L into an optimized fuel quantity value S; and completing the closed-loop adjustment of fuel injection quantity (FIQ).

This invention provides a fuel injection method for an engine, an engine, a vehicle, and a computer-readable storage medium, relating to the field of vehicle exhaust emission control technology. The fuel injection method provided by this invention includes the following steps: Before the engine reaches a stable idle speed, fuel is injected at a preset fuel pressure during the first intake stroke and the first compression stroke of each working cycle, wherein the fuel injection mass ratio of the first intake stroke to the first compression stroke is greater than 4:1, and the preset fuel pressure ranges from 20 to 50 MPa. When the engine speed is at a stable idle speed, fuel is injected during the second intake stroke and the second compression stroke of each working cycle at a preset fuel pressure, wherein the fuel injection mass ratio of the second intake stroke to the second compression stroke is greater than or equal to 4:1. This method ensures that the vehicle's exhaust emission level meets the requirements of Euro 6 emission standards without requiring a particulate filter, thus optimizing the engine's original emissions.

The invention aims to provide a single needle valve type high-response methanol-diesel injector based on opposed electromagnetic valve control, and belongs to the field of engines. Opposite type double-medium channel control assemblies are installed in an ejector connector body, an ejector middle body and an ejector throttling block, a methanol / diesel shared nozzle assembly is installed in a nozzle body, a diesel connector and a methanol connector are installed on the side of the ejector connector body, a high-pressure diesel channel is arranged in the diesel connector, and a high-pressure methanol channel is arranged in the methanol connector. Free connection and disconnection of an internal high-pressure methanol path and an internal high-pressure diesel path can be controlled, then independent injection of methanol fuel and diesel fuel is achieved, the two fuel injection modes are controlled through the same needle valve, the fuel is injected through the same injection hole, and the advantages of being high in reliability and simple in structure are achieved. And after methanol / diesel oil injection is finished, rapid cut-off of an internal passage of the injector and rapid seating of the needle valve can be achieved, and the response characteristic of fuel injection mode switching of the injector is improved.

A method includes applying a first current to a control valve having an actuated state and a resting state, the first current causing the control valve to move from the resting state to the actuated state. The method includes applying a second current that causes the control valve to remain in the actuated state, the second current having an amplitude that is lower than an amplitude of the first current. The method includes maintaining the second current for a duration. The method includes stopping the second current at an end of the duration to allow the control valve to return to the resting state. The method includes measuring a control valve return time. The method includes setting an amplitude of current for a fuel injection event based on the control valve return time.

A fuel burner tube (1) for a combustion chamber burner comprises a tubular body (2) extending along a longitudinal axis with external (21) and internal (22) surfaces. The tubular body (2) has a premixing area (25) within the internal surface (22) where oxidant gas is premixed with fuel. One or more radially arranged through holes (3) on the internal surface (22) inject a lateral purging flow downstream toward the premixing area (25). A centerbody (4) within the tubular body (2) extends from a first end (23) to the premixing area (25), allowing the introduction of a central purging flow. At least one fuel injection channel (5), connectable to a fuel injection system, is positioned downstream of the centerbody (4) on the internal surface (22) in correspondence with the premixing area (25) to inject fuel into the premixing area (25).

The ammonia combustion and reforming system for high-efficiency hydrogen production includes a combustion chamber, a fuel injection unit that generates a combustion gas by combusting at least first air and first ammonia inside the combustion chamber, and an ammonia decomposition unit that is at least partially provided inside the combustion chamber and in which ammonia for decomposition is decomposed, wherein thermal energy of the combustion gas is transferred to the inside of the ammonia decomposition unit, so that the ammonia for decomposition is decomposed to generate a decomposition gas.