SYSTEM FOR DETECTING AND CONTROLLING FUEL GAS COMPONENTS

Abstract

System (100) for detecting and controlling a fuel gas composition, the system comprising: several microsensors (251) installed in a single chamber (250), each of the microsensors (251) being designed to detect a characteristic value of a mixture of gaseous fuel introduced into the chamber (250); several heating elements, each of the heating elements being assigned to one of the several microsensors (251) and the several heating elements being designed to simultaneously raise the temperature of the mixture of gaseous fuel at each of the several microsensors (251) to a different temperature level at each of the microsensors (251); and a microprocessor (254) designed to: Determining a thermodynamic property of the mixture of gaseous fuel at the different temperature levels at each of the microsensors (251) as a function of the characteristic value detected by the individual microsensors; Correlate the thermodynamic property with a fuel gas composition of the mixture of gaseous fuel; and Control of the quantity of at least one component in the mixture of gaseous fuel as a function of the fuel gas composition, which has been determined by correlation.

Description

State of the art

[0001] The present disclosure relates generally to a system for detecting proportions of fuel gas components and more specifically to a system for detecting and controlling proportions of fuel gas components in a mixture of gaseous fuel supplied to an internal combustion engine or motor. background

[0002] Gaseous fuel-powered engines can operate using a range of different fuels or fuel mixtures. Different fuel mixtures can result in varying amounts of pollutants such as nitrogen oxides and nitrogen dioxide (NO₂) being produced during combustion. xVarious environmental regulations have created a need to significantly reduce pollutant levels without limiting engine performance, as measured by the maximum Brake Mean Effective Pressure (BMEP). In some combustion engines, stoichiometric combustion can be used in conjunction with special catalysts in an exhaust aftertreatment system to reduce NOₓ emissions. x -proportions produced during combustion. However, this can lead to high combustion temperatures and an increased tendency to knock, thus limiting the engine's BMEP (BMW Energy Performance). Therefore, various alternative methods can be used to reduce the proportions of pollutants such as NO. xThe processes involved in combustion include precise control of the quantities of various components in the fuel, such as the hydrogen content. Accurate monitoring and control of the fuel composition and engine operating parameters enable improved performance and reduced emissions. Catalytic partial oxidation (CPOx) reforming is a process that can be applied during engine operation to modify the hydrogen content of the air-fuel mixture during combustion, thereby improving thermal efficiency and combustion stability.

[0003] Traditionally, the physical properties of gaseous fuels used to power internal combustion engines were determined by controlling the temperature and / or pressure of the gaseous fuel or by composition analysis, such as that performed using gas chromatography, without controlling temperature or pressure. Methods for measuring the quality and composition of gaseous fuels allow for the determination of the heat range that can be obtained from a specific gaseous fuel mixture. An engine using a particular gaseous fuel mixture of a specific quality and heat range can, for example, be operated by controlling the ignition and fuel injection to maintain or improve power output and reduce emissions.Some current techniques for continuous analysis of a gaseous fuel stream during engine operation use expensive measuring instruments that require constant maintenance and exhibit a lack of reliability under harsh field operating conditions.

[0004] One approach to addressing the problems described above is disclosed in U.S. Patent 5,311,447 A (Patent '447), which was granted to Bonne on May 10, 1994. Specifically, Patent '447 discloses a non-combustion process for measuring the quality of a fuel supplied to a fuel-consuming device. The process involves diverting a portion of the fuel through a sensor chamber and measuring the viscosity of the fuel at a first sensor in the chamber. The process also includes measuring the thermal conductivity of the fuel with a second sensor in the chamber at two different temperature levels.The viscosity and thermal conductivity values ​​are then corrected based on the fuel's temperature and pressure, and a corresponding heat range is determined using an empirical formula derived as a function of the corrected viscosity and thermal conductivity values. The heat range is then stored, displayed, or output depending on the information required for a specific application. The empirical formula used to measure the fuel's heat range is determined using commercially available regression analysis software.

[0005] Although the method described in patent 447 may be sufficient for some applications, it can be suboptimal. For example, the method relies on determining at least two different fuel gas properties, such as viscosity and thermal conductivity, and subsequently deriving a characteristic value of the fuel gas, such as heat content, using the two determined properties. As a result, the associated system requires at least two different types of sensors, which increases costs, and can have relatively long response times depending on the measurement of different fuel properties. The speed of the system may preclude its use in highly variable applications (e.g., internal combustion engine applications) from the outset.

[0006] The disclosed system is designed to overcome one or more of the problems mentioned above and / or other problems associated with existing systems for determining gas compositions. Summary

[0007] In one aspect, the present disclosure relates to a system for detecting and controlling the composition of a fuel gas. The system can include multiple microsensors installed in a single chamber, each of which is designed to detect a characteristic value of a mixture of gaseous fuel introduced into the chamber. The system can also include multiple heating elements, each of which is associated with one of the multiple microsensors and the multiple heating elements being designed to implement a different temperature level at each of the microsensors.The system can also include a microprocessor designed to determine a thermodynamic property of the gaseous fuel mixture at the different temperature levels at each of the microsensors as a function of the characteristic value detected by the individual microsensors, to correlate the thermodynamic property with a fuel gas composition of the gaseous fuel mixture, and to control an amount of at least one component in the gaseous fuel mixture as a function of the fuel gas composition determined by the correlation.

[0008] In another aspect, the present disclosure relates to a control system for use with an engine. The control system can include several microsensors installed in a single microchamber and designed to detect a characteristic value of a mixture of gaseous fuel introduced into the microchamber, and several resistance heating elements associated with each of the several microsensors and designed to implement a different temperature level at each of the several microsensors.The system can also include a microprocessor designed to determine a thermodynamic property of the gaseous fuel mixture at different temperature levels at each of the microsensors as a function of the characteristic value detected by the individual microsensors, to correlate the thermodynamic property with a fuel gas composition of the gaseous fuel mixture, and to control an amount of at least one component in the gaseous fuel mixture and an operating parameter of the engine as a function of the fuel gas composition determined by the correlation.

[0009] Another aspect of the present disclosure relates to a method for controlling an engine. The method may include diverting successive portions of a mixture of gaseous fuel supplied to the engine into a microchamber, where each successive portion is temporarily held under substantially steady conditions. The method may further include simultaneously heating each of several microsensors to a different temperature level at several different, spaced-apart locations within the microchamber and determining an overall thermal conductivity for each successive portion of the mixture of gaseous fuel.The method may also include the selective adjustment of a proportion of a component present in the gaseous fuel mixture and / or a control parameter of the internal combustion engine based on thermal conductivity. Brief description of the drawings Drawing 1 is a schematic representation of an example of a disclosed system; Fig. Figure 2 is a schematic representation of an example of a disclosed engine control system; and Fig. 3 is a flowchart that represents an example of a disclosed procedure that is derived from the system of Fig. 1 can be carried out. Detailed description

[0010] Fig. Figure 1 shows an example system 100 for detecting and controlling the quantity of one or more components in a mixture of gaseous fuel supplied to an engine. By providing accurate real-time measurements of the quantities of the various components in the mixture of gaseous fuel, the system 100 enables precise control of the combustion process to maintain or increase power output while reducing the generation of pollutants. An internal combustion engine can, for example, be a four-stroke gaseous engine controlled by an engine control module (ECM) 170. However, a person skilled in the art will recognize that the engine can alternatively be a two-stroke engine, if desired. The engine can include an engine block that defines at least one or more cylinders.Within each cylinder, a piston can be arranged to slide between a position at top dead center (TDC) and a position at bottom dead center (BDC), and each cylinder can be associated with a cylinder head. The cylinder, piston, and cylinder head together can define a combustion chamber. The engine can include any number of combustion chambers arranged in a line configuration, a V configuration, an opposite configuration, or any other suitable configuration.

[0011] The gaseous fuel mixture supplied to the individual combustion chambers in the engine can first be compressed and then cooled, for example by a cooler 130, before being injected into the individual cylinders in an air-fuel mixture. The system 100 can be configured to divert successive portions of the cooled gaseous fuel mixture from the cooler 130 into a microchamber 150, which may contain several microsensors, each designed to detect a characteristic value of the gaseous fuel mixture. This characteristic value can be output to a processor and used to determine a thermodynamic property of the gaseous fuel mixture.The thermodynamic property can be correlated by the processor, for example, with the proportions of components in the composition of the gaseous fuel mixture 160, such as the molar percentages of O2, H2, N2, NO2, CO, CO2, and / or CH4. In one embodiment, the microchamber 150 can contain four spaced-apart microsensors, each of which is associated with a resistance heater. Each of the resistance heaters and each of the microsensors can be a microelectromechanical system (MEMS) consisting of components ranging in size from 1 to 1000 micrometers. The term "microsensor," as used herein, can also include small devices, such as miniature encoders, that do not necessarily fall within the size range of 1 to 1000 micrometers but are miniaturized devices and structures that can be fabricated using microfabrication techniques.

[0012] Each microsensor in the microchamber 150 can include a variable electrical resistance whose resistance changes with respect to a change in temperature. The variable electrical resistance for each microsensor can be a microheater located in close proximity to the associated microsensor on a semiconductor substrate. The semiconductor substrate can be formed from a silicon or silicon nitride chip and can be positioned within the microchamber 150 such that it is at least partially surrounded by each successive portion of the cooled gaseous fuel mixture introduced into the microchamber 150. The microheater can be mounted above the substrate on suspension arms or applied as a thin-film resistor on a thin membrane bonded to the substrate.Some examples of variable electrical resistances may include a nanocalorimeter, a thermal conductivity sensor, a microthermistor, a MEMS element, a microbolometer platform, a microwire, a microcoil, or any variable electrical resistance device that is bonded to or otherwise connected to the membrane, or that is stored near the substrate by other means. Standard fabrication processes for complementary metal-oxide semiconductors (CMOS) or MEMS fabrication processes can be used to fabricate the electrical resistance device on the substrate. The substrate may consist of a silicon or silicon nitride membrane enclosing an electrical CMOS read circuit or any integrated CMOS device. The substrate or microsensor devices may be, respectively,The microsensors can be partially or completely enclosed within a pressurized gas environment comprising the successive portions of the cooled gaseous fuel mixture received from the cooler 130 in the microchamber 150. The environment enclosing the individual microsensors can be filled with successive, relatively steady volumes of the gaseous fuel mixture, which exert a uniform pressure throughout the environment, including the upper and lower surfaces of the variable electrical resistances. The gaseous fuel mixture can include components such as O2, H2, N2, NO2, CO, CO2, CH4, and any other trace gases or pollutant gases.

[0013] In the embodiment described in Fig. As shown in Figure 2, a microchamber 250 can contain four microsensors 251 spaced apart within the microchamber 250 and each supplied with electrical power from an electrical power system 282. Piezoelectric microvalves 247 can be provided at an inlet and an outlet of the microchamber 250 to control the flow of successive volumes of the gaseous fuel mixture supplied to and from the microchamber 250 by the fuel system 220. The piezoelectric microvalves 247 can also be actuated by direct current power supplied by a programmable direct current source 280. The four microsensors 251 can be activated in parallel, and each of the variable resistors of each of the four microsensors 251 can supply a different voltage (V). heater ) and another current (I heater) received, so that 4 different temperatures are reached essentially simultaneously at the 4 spaced-apart locations in the microchamber 250. The term "essentially simultaneously" means that the 4 different microsensors all reach thermal equilibrium at different temperatures within 250 milliseconds (ms) after each of the successive volumes of the gaseous fuel mixture has been introduced into the microchamber 250. The variable resistors of each of the microsensors 251 can receive a voltage and a current, each sufficient to ensure that the temperature of each resistor is at least 10% higher than the temperature of the gaseous fuel mixture from the cooler 130 ( Fig. 1) or from the fuel system 220 ( Fig. 2) This minimal temperature difference between the gaseous fuel mixture introduced into the microchamber and the heating temperature of each of the resistors is sufficient to cause enough heat exchange through the surrounding gas to provide an accurate indication of the system's thermal conductivity. Each of the microheaters associated with the individual microsensors can have a heat radiation area small enough to be considered a point heat source. The volume of gas surrounding each microheater can also be small enough to allow thermal equilibrium to be reached in less than 250 ms after the introduction of each successive portion of the gaseous fuel mixture into the microchamber. Therefore, the heat transfer coefficient of the gaseous mixture is essentially proportional to its thermal conductivity.

[0014] An average person will recognize that alternative methods can also be used to introduce successive volumes of the gaseous fuel mixture into microchamber 150 for testing and then to expel each successive volume from the microchamber. One advantage of an arrangement such as that described in Fig. As shown in Figure 2, the actuation of the microvalves 247 is very rapid and can enable a complete change of the gas volume in the microchamber 250 approximately every 250 ms (about 4 times per second). The use of four different microsensors 251, arranged within the microchamber 250 and essentially simultaneously exposed to four different temperatures, also allows for the rapid determination of four data points of a thermodynamic property from each of the successive volumes of the gaseous fuel mixture. The input and output voltages from the four different microsensors 251 can be used in the construction of a linear good-fit or best-fit regression model using partial least squares (PLS) methods to estimate various parameters of the gaseous fuel mixture.Output signals from each of the microsensors 251 can be processed by a dynamic metrology module (DMM) 252, and a microcontroller 254 can use this information to send appropriate control signals to the programmable DC power supply 280. While successive volumes of the gaseous fuel mixture are being analyzed by the DMM 252, the programmable DC power supply 280 can control the opening and closing of each of the microvalves 247 to execute each of the successive volumes and introduce a different volume of the gaseous fuel mixture into the microchamber 250.

[0015] The temperature of each of the variable electrical resistors can be a function of the applied electrical power and of heat transfer to the substrate and to the gaseous environment of each variable electrical resistor within the microchamber 250. A voltage and / or a current source can be connected to each of the variable electrical resistors of the microsensors 251 to electrically excite the individual resistors. Since each of the variable electrical resistor devices associated with the individual microsensors (251) exhibits electrical resistance, this electrical excitation causes the individual resistors to heat up to a specific temperature as a function of the applied electrical power due to the Joule effect.The temperature of each variable electrical resistance at equilibrium is a function of the applied electrical power, the heat transfer to the microsensor substrate, and the heat transfer to the environment of the individual microsensors via several heat transfer mechanisms such as conduction, convection, and radiation. The temperature at the substrate of each microsensor can be measured, for example, by a voltage output from a thermopile, or by one or more thermocouples or other temperature sensing device attached to the substrate. A systemic thermal conductivity (G) of the mixture of gaseous fuel and a membrane of the associated microsensor can be calculated from G = Q ΔT, where: Q = P (heating power), P = V. heater I heater The temperature difference of the thermopile or other temperature sensing device is given by: ΔT = V output / S, where S is the sensitivity of the thermopile or other temperature sensing device. ΔT is the temperature difference of the temperature sensing device. The heater temperature can be estimated from its resistance and from a calibrated temperature-resistance response of the heater. Dynamically measured thermodynamic properties of the gaseous fuel mixture can be directly correlated with the composition of the gaseous fuel mixture.

[0016] In one embodiment, the method of detecting a gas composition using multiple variable electrical resistance devices and microsensors can be based on probing the thermal response of all successive volumes of a gaseous fuel mixture introduced into the microchamber 250 with modulated electrical excitations. The thermal response can be determined by the heat capacity and thermal conductivity of the gas in the vicinity of each microsensor. In the thermal domain, the variable electrical resistance can exhibit low-pass behavior, and the phase delay for each resistance can be determined by the thermodynamic properties of the surrounding gas. The thermodynamic properties of the gas can be directly correlated with its composition and pressure.Measuring the phase delay of each resistor in the thermal domain for all successive volumes of a gaseous fuel mixture introduced into microchamber 250 thus provides information about the gas composition and pressure. The Joule heating results from a periodically modulated electrical excitation, where the electrical excitation is modulated simultaneously with a periodic electrical signal. The periodic electrical signal can be a sinusoidal signal, a quadratic signal, a binary signal, a pulsed signal, or any limited periodic signal. The gas detection method can include measuring the phase delay (or a time delay) between the thermal response of the variable electrical resistance and the modulated electrical excitation.The phase delay (or time delay) enables real-time measurement of the heat capacity and thermal conductivity of the surrounding gas. Both the heat capacity and thermal conductivity can be correlated with the gas composition and pressure and continuously updated as successive volumes of a gaseous fuel mixture are introduced into the microchamber 250.

[0017] As in Fig. 1 and Fig. As shown in Figure 2, the ECM 170, 270 can be designed to use the determined or established percentages of one or more components in the gaseous fuel mixture in order to, as shown in Figure 2, Fig. 1 shown, a control signal for a fuel mixing valve 180 or, as in Fig. 2 shown, for the fuel system 220. The fuel mixing valve 180 can be operated in conjunction with a source of one or more components to make real-time adjustments to the proportions of the one or more components during engine operation. As shown in Fig. As shown in Figure 1, an example of real-time adjustment of the proportion of a component in the gaseous fuel mixture can include a catalytic partial oxidation (CPOx) process 120 for the production of reformed gas. The CPOx process 120 can be implemented during engine operation in conjunction with the fuel mixing valve 180 to provide additional amounts of H2 in the gaseous fuel mixture. The addition of H2 to the gaseous fuel mixture can improve the thermal efficiency and combustion stability of the gaseous fuel mixture.

[0018] The CPOx process can be carried out using a suitable catalyst in a fuel reformer associated with the System 100, which is designed to reform a hydrocarbon fuel into a hydrogen-rich gas comprising mainly CO, H2, CO2, and H2O. The H2-rich gas produced by the CPOx process can then be added using the fuel mixing valve 180 in quantities controlled by the ECM 170 and dependent on the H2 content detected in each successive volume of the gaseous fuel mixture by the microsensors in the microchamber 150.

[0019] Additional engine control functions can be implemented by the ECM 170, 270 based on the specific proportions of various components in the gaseous fuel mixture. As is known in engineering, an internal combustion engine may include a crankshaft that is rotatably mounted within an engine block. A connecting rod can link each piston to a crank throw of the crankshaft, so that a sliding motion of the piston between the TDC and BDC positions within the respective cylinder results in a rotation of the crankshaft. Likewise, a rotation of the crankshaft can result in a sliding motion of the piston between the TDC and BDC positions. In a four-stroke engine, the piston can move back and forth between the TDC and BDC positions through an intake stroke, a compression stroke, a combustion or power stroke, and an exhaust stroke.In a two-stroke engine, a complete cycle can include a compression / exhaust stroke (BDC to TDC) and a power / exhaust / intake stroke (TDC to BDC). The cylinder head can define an intake port and an exhaust port. The intake port can direct compressed air or a mixture of air and fuel from an intake manifold through an intake port and into the individual combustion chambers. Likewise, the exhaust port can direct exhaust gases from the combustion chamber through an exhaust port and into an exhaust manifold. An intake valve can be located within an intake port and designed to selectively engage with a corresponding seat. Each intake valve can be movable between a first position, in which the intake valve engages with the seat and restricts fluid flow with respect to the intake port, and a second position, in which the intake valve is disengaged from the seat to allow fluid flow.Similarly, an intake valve can be arranged within an exhaust port and designed to selectively engage with a corresponding seat. Each exhaust valve can be movable between a first position, in which the exhaust valve engages with the seat and restricts fluid flow with respect to the exhaust port, and a second position, in which the exhaust valve is removed from the seat to allow fluid flow.

[0020] A number of valve actuation assemblies (not shown) can be operationally connected to the engine to move intake and exhaust valves at desired times relative to the rotation of the crankshaft and / or the position of each piston between its first and second positions. Each cylinder head can include multiple intake ports and multiple exhaust ports. Each of these ports can be associated with either an intake valve or an exhaust valve. The engine can include a valve actuation assembly for each cylinder head, designed to actuate all the intake valves of all the exhaust valves of that cylinder head. If desired, a single valve actuation assembly could actuate the intake valves or the exhaust valves associated with multiple cylinder heads.The valve actuation assemblies can each be configured, for example, as a cam / pushrod / rocker arm arrangement, as a magnetic drive, as a hydraulic actuator, and / or any other actuating device known in the art. The times at which intake and exhaust valves are opened and / or closed can have an effect on engine operation (e.g., an effect on the temperature, efficiency, ignition timing, etc., of a cylinder) and, in some embodiments, can be variably controlled according to the detected proportions of one or more components in each successive volume of a gaseous fuel mixture analyzed within the microchamber 150, 250.

[0021] The in Fig. The fuel system 220 shown can be configured, for example, as a fuel mixing valve, a fuel injection nozzle, a carburetor, etc., each connected to the intake manifold. Depending on requirements, the fuel system 220 can be driven electronically, hydraulically, mechanically, and / or pneumatically to deliver pressurized fluid directly to the individual combustion chambers or indirectly via the intake manifold or a fuel line system. The fuel can include a compressed gaseous fuel, such as a mixture of natural gas, propane, biogas, landfill gas, hydrogen, and / or another fuel.

[0022] The amount of fuel admitted to the intake manifold by the fuel system 220, and / or the time at which the fuel is admitted to the intake manifold, can be associated with an air-to-fuel ratio (A / F) admitted to the individual combustion chambers. More precisely, in a case where it is desired to introduce a lean air-fuel mixture (i.e., a mixture with a relatively small amount of fuel compared to the amount of air) into a combustion chamber, the fuel system 220 can cause fuel to be directed to the intake manifold (and / or combustion chamber) over a shorter period of time than in a case where a rich air-fuel mixture (i.e., a mixture with a relatively large amount of fuel compared to the amount of air) is desired.Similarly, in a case where a rich air-fuel mixture is desired, the fuel system 220 can cause fuel to be directed into the intake manifold over a longer period (or otherwise controlled to inject more fuel per cycle) than if a lean mixture were desired. The determination of various proportions of components in the gaseous fuel mixture can be used by the ECM 270 as input to assist in the regulation of engine actuators (e.g., to control the intake valve, the exhaust valve, the fuel system 220, an engine-driven consumer, etc.).

[0023] The DMM 252 and the microcontroller 254 can be configured to receive the signals generated by the individual microsensors 251 within the microchamber 250 approximately every 250 ms and to calculate one or more thermodynamic properties of the gaseous fuel mixture based on these signals. An average person will recognize that the frequency at which the DMM 252 and the microcontroller 254 can receive signals generated by the microsensors 251 can be varied depending on how quickly each successive volume of gaseous fuel mixture can be delivered to and removed from the microchamber 250. The frequency at which signals can be received can also vary significantly depending on how long each volume of gaseous fuel takes to reach thermal equilibrium after the microheaters associated with the individual microsensors have been activated.In the disclosed embodiment, the thermodynamic characteristic can be the systemic thermal conductivity (G) of the gaseous fuel mixture. Other characteristic values ​​can include an air-fuel ratio (A / F), a lower heating value (LHV), a wobble index (WI), a specific density (Sg), a methane number (MN), and a specific heat ratio (γ). The microcontroller 254 can calculate the thermodynamic characteristics using one or more empirical formulas stored in memory.

[0024] The Microcontroller 254 and the ECM 270 can each be implemented as a single processor or as multiple processors, including or including a device for controlling the operation of the engine system. Numerous commercially available processors can perform the functions of the Microcontroller 254 and the ECM 270. The ECM 270 can also include or be associated with memory for storing data such as operating conditions, design constraints, performance characteristics or specifications of the engine system, optional instructions, and corresponding fuel quantity parameters. Various other circuits can be associated with the ECM 270, including a power supply circuit, a signal conditioning circuit, a magnet drive circuit, a communication circuit, and other suitable circuits.Furthermore, the ECM 270 can communicate with other components of the engine system (e.g., with the valve actuation assemblies, the fuel system 220, the fuel mixing valve 180, the engine-driven consumer, etc.) either via a wired or wireless transmission, and thus the ECM 270 can be connected to the engine or alternatively located at a remote location.

[0025] The ECM 270 can be configured to adjust engine operation based on fuel quality parameters and the composition of the gaseous fuel mixture, calculated by the microcontroller 254. For example, the ECM 270 can cause intake and / or exhaust valves to open earlier, remain open longer, and / or open with a different stroke relative to piston movement. This change in valve timing can affect the amount of air and / or fuel admitted to the combustion chamber, and the resulting pressure, temperature, efficiency, and / or emissions.Similarly, the ECM 270 can cause the fuel system 220 to deliver more or less fuel into the intake manifold (and / or combustion chamber) at any desired time, thereby altering the engine's air-fuel ratio and the resulting changes in RPM output, power output, efficiency, emissions, etc. The ECM 270 could also be able to modify the engine load, for example, by increasing or decreasing it. The ECM 270 could affect the engine's operation in other ways as well.

[0026] The ECM can also adjust engine operation based on thermodynamic characteristics and the composition of the gaseous fuel mixture to improve operation under a specific set of conditions. That is, based on the characteristics of the gaseous fuel mixture, the ECM 270 can modify engine operation to prevent harmful situations (e.g., engine knocking, overpressure, overheating, etc.), improve efficiency and / or power output, and / or achieve other user-defined objectives. Fig. Figure 3 shows a flowchart that represents a method for detecting and controlling the proportions of fuel gas components based on a thermodynamic characteristic value of the fuel. Fig. 3 will be discussed in more detail in the following section to further illustrate the concepts revealed. Commercial applicability

[0027] The disclosed system can be industrially applicable in situations involving a change in fuel supply or a mixture of gaseous fuel with an unknown composition, where continued operation of the associated engine at high power levels and with reduced pollutant emissions is desired. The disclosed system can help ensure continued operation by selectively implementing engine-protective adjustments based on changes in fuel quality parameters detected by the system. The disclosed engine system can also help ensure high engine performance by selectively implementing adjustments to the amounts of one or more components in the gaseous fuel mixture supplied to the engine to achieve desired engine operating parameters.An example process for measuring and controlling the quantity of a component in the gaseous fuel mixture is shown in . Fig. 3 shown.

[0028] As in Fig. As shown in Figure 3, the first step (step 310) can involve allowing a fuel gas sample to flow into a sensor chamber (microchamber 250) and holding the fuel gas sample in the microchamber 250 at essentially zero velocity for a period of time. As discussed above, the small volume of the microchamber 250 can allow thermal equilibrium to be reached rapidly, for example in 250 ms or less, making it possible for the system to perform a rapid succession of gas samples for determining a particular thermodynamic characteristic and composition of the gas.

[0029] The second step (step 320) can involve applying a different current (I heater ) and / or another voltage (V heater) to a microheater assigned to the respective specific microsensor 251 in the microchamber 250, in order to generate a different heating temperature at each of the microsensors 251. After the individual microheaters and the surrounding gas have reached thermal equilibrium, the third step (step 330) can determine a system conductance (G) as a function of the heating resistances (R). heater ) and a thermopile voltage output (V output ) on the substrate of each microsensor. As discussed above, the systemic thermal conductivity is: G = (SV heater I heater ) / V output S is the sensitivity of the thermopile or other temperature sensing device. The temperature can be measured by a thermopile, one or more thermocouples, or another temperature sensing device.

[0030] After determining the systemic thermal conductivity G, the fourth step (step S340) can correlate the systemic conductivity G, the heating temperature T and the thermopile output voltage V. output , measured at the different heating voltages (V heater ) and flows (I heater ), including fuel gas parameters and components. The dynamic metrology module (DMM) 252, the microcontroller 254, and the engine control module 270 can then use the correlated fuel gas characteristics in the fifth step (step 350) to control the production of H2, which is to be added to the fuel gas mixture, using a catalytic partial oxidation (CPOx) reforming process. The addition of H2 to the gaseous fuel mixture can improve the thermal efficiency and combustion stability of the gaseous fuel mixture or improve engine performance while simultaneously reducing emissions.

[0031] The disclosed system can provide several advantages. First, the disclosed system can be relatively simple, as it only has one type of microsensor, e.g., a microsensor capable of detecting the thermal conductivity of a gas. This simplicity can help reduce the cost of the system. Furthermore, by simultaneously determining thermodynamic properties of the gaseous fuel mixture at multiple locations within a microchamber, the accuracy of the measurement can be increased. More precisely, a theoretical accuracy was calculated for a system that uses four microsensors within a microchamber, where electrical power is supplied to each of the four microheaters of the four microsensors, resulting in temperatures of 98, 158, 218, and 278 °C at the individual microcontrollers.The simulated capability of this system was determined using a general gas law to enable the calculation of the mole percent of H2, CO, CO2, CH4, and N2 with an accuracy of less than ±1% over a full-scale measurement range (where full-scale accuracy (FS) is the best straight-line fit using a linear partial least squares (PLS) regression method). Since only a single thermodynamic property is needed to determine the composition of a corresponding mixture of gaseous fuel, the system can respond well and offer diverse application possibilities in unstable systems.

[0032] It will be obvious to a person skilled in the art that various modifications and variations of the system of the present disclosure are possible. Other embodiments of the system will become clear to the person skilled in the art after considering the description and the practical implementation disclosed herein. The description and the examples are to be regarded merely as examples, the true scope of protection of the disclosure being specified by the following claims and their equivalents.

Claims

[1] System (100) for detecting and controlling a fuel gas composition, the system comprising: several microsensors (251) installed in a single chamber (250), each of the microsensors (251) being designed to detect a characteristic value of a mixture of gaseous fuel introduced into the chamber (250); several heating elements, each of the heating elements being assigned to one of the several microsensors (251) and the several heating elements being designed to simultaneously raise the temperature of the mixture of gaseous fuel at each of the several microsensors (251) to a different temperature level at each of the microsensors (251); and a microprocessor (254) designed to: Determining a thermodynamic property of the mixture of gaseous fuel at the different temperature levels at each of the microsensors (251) as a function of the characteristic value detected by the individual microsensors; Correlate the thermodynamic property with a fuel gas composition of the mixture of gaseous fuel; and Control of the quantity of at least one component in the mixture of gaseous fuel as a function of the fuel gas composition, which has been determined by correlation. [2] System according to claim 1, wherein the thermodynamic property is a thermal conductivity of the mixture of gaseous fuel. [3] System according to claim 1, wherein the microprocessor (254) is designed to determine the thermodynamic property as a function of a voltage and / or current applied to the individual heating elements associated with the individual microsensors (251). [4] System according to claim 1, wherein the microprocessor is designed to determine the thermodynamic property as a function of an electrical power supplied to each of the multiple heating elements and a temperature detected at each of the associated microsensors (251). [5] System according to claim 4, wherein the microprocessor (254) is designed to receive a voltage signal indicating a temperature detected by a thermocouple arranged on a substrate of each of the microsensors (251) after the mixture of gaseous fuel at each of the microsensors (251) has reached thermal equilibrium following the injection of electrical power into each of the multiple heating elements. [6] System according to claim 1, wherein the microprocessor is designed to control an amount of H2 in the mixture of gaseous fuel. [7] System according to claim 6, wherein the microprocessor is designed to: Controlling the production of the amount of H2 to control a catalytic partial oxidation process carried out by a reformer to produce H2; and Controlling the addition of H2 produced by the reformer to the mixture of gaseous fuel. [8] System according to claim 1, wherein the microprocessor is further designed to control an operating parameter of an internal combustion engine designed to burn the mixture of gaseous fuel, at least in part on the basis of the amount of the at least one component in the mixture of gaseous fuel. [9] System according to claim 8, wherein the operating parameter of the internal combustion engine is at least one of the following: an air / fuel ratio, an ignition time, a fuel injection time, a fuel injection quantity or a load of the internal combustion engine. [10] Method for controlling an internal combustion engine, comprising: Diverting successive portions of a mixture of gaseous fuel supplied to the internal combustion engine into a microchamber (250); Temporarily holding each of the successive portions in a substantially quiescent state in the microchamber (250); Heating each of the successive portions of the gaseous fuel mixture simultaneously to several different temperature levels at several different, spaced-apart locations within the microchamber (250); Determine an overall thermal conductivity for each of the successive portions; and selective adjustment of a proportion of a component present in the mixture of gaseous fuel and a control parameter of the internal combustion engine based on thermal conductivity.

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