A system for sensing and controlling a fuel gas composition may include a plurality of micro-sensors mounted in a single chamber, with each of the micro-sensors being configured to sense a characteristic of a mixture of gaseous fuel introduced into the chamber. The system may also include a plurality of heating elements, with each of the heating elements being associated with one of the plurality of micro-sensors, and the plurality of heating elements being configured to implement a different temperature level at each of the micro-sensors. The system may also include a microprocessor configured to determine a thermodynamic property of the mixture of gaseous fuel at the different temperature levels at each of the micro-sensors as a function of the characteristic sensed by each micro-sensor, correlate the thermodynamic property to a fuel gas composition of the mixture of gaseous fuel, and control an amount of at least one constituent in the mixture of gaseous fuel as a function of the fuel gas composition determined by the correlation.

A system for sensing and controlling a fuel gas composition may include a plurality of micro-sensors mounted in a single chamber, with each of the micro-sensors being configured to sense a characteristic of a mixture of gaseous fuel introduced into the chamber. The system may also include a plurality of heating elements, with each of the heating elements being associated with one of the plurality of micro-sensors, and the plurality of heating elements being configured to implement a different temperature level at each of the micro-sensors. The system may also include a microprocessor configured to determine a thermodynamic property of the mixture of gaseous fuel at the different temperature levels at each of the micro-sensors as a function of the characteristic sensed by each micro-sensor, correlate the thermodynamic property to a fuel gas composition of the mixture of gaseous fuel, and control an amount of at least one constituent in the mixture of gaseous fuel as a function of the fuel gas composition determined by the correlation.

A method using a gas reservoir and a critical nozzle for determining physical properties and/or quantities relevant to combustion of gas or gas mixtures, the method includes: flowing a gas or gas mixture under pressure from the gas reservoir through the critical nozzle; measuring pressure drop in the gas reservoir as a function of time; determining a gas property factor (*), dependent on physical properties of the gas or gas mixture, based on the measured values of the pressure drop; and determining a desired physical property or quantity relevant to combustion based on the gas property factor (*) through correlation.

A method using a gas reservoir and a critical nozzle for determining physical properties and/or quantities relevant to combustion of gas or gas mixtures, the method includes: flowing a gas or gas mixture under pressure from the gas reservoir through the critical nozzle; measuring pressure drop in the gas reservoir as a function of time; determining a gas property factor (*), dependent on physical properties of the gas or gas mixture, based on the measured values of the pressure drop; and determining a desired physical property or quantity relevant to combustion based on the gas property factor (*) through correlation.

A method to determine a physical property or a quantity of gas related to combustion including: flowing a gas from a reservoir through a critical nozzle and past a microthermal sensor wherein the mass flow of the gas through the critical nozzle is the same as the mass flow through the microthermal sensor; measuring the pressure drop in the reservoir as a function of time; deriving a first gas property factor based on a time constant of the pressure drop; determining a second gas property factor which depends from a flow signal generated by the microthermal sensor; determining a thermal conductivity of the gas; and determining the physical property or quantity based on a correlation between the physical property or quantity, and the first and/or second gas property factors and the thermal conductivity.

A method for determining physical properties of combustion including: flowing a gas a critical nozzle and past a microthermal sensor wherein the mass flow of the gas through the critical nozzle is the same as the mass flow through the microthermal sensor; measuring the pressure drop in a reservoir of gas flowing to the nozzle; determining a first gas property factor based on the measured pressure drop; determining a second gas property factor based on a flow signal generated by the microthermal sensor; determining a thermal conductivity of the gas using the microthermal sensor; and determining a physical property of the combustion based on a correlation of the first and/or second gas property factors and the thermal conductivity.

A method for determining physical properties of combustion including: flowing a gas a critical nozzle and past a microthermal sensor wherein the mass flow of the gas through the critical nozzle is the same as the mass flow through the microthermal sensor; measuring the pressure drop in a reservoir of gas flowing to the nozzle; determining a first gas property factor based on the measured pressure drop; determining a second gas property factor based on a flow signal generated by the microthermal sensor; determining a thermal conductivity of the gas using the microthermal sensor; and determining a physical property of the combustion based on a correlation of the first and/or second gas property factors and the thermal conductivity.

A system for sensing and controlling a fuel gas composition may include a plurality of micro-sensors mounted in a single chamber, with each of the micro-sensors being configured to sense a characteristic of a mixture of gaseous fuel introduced into the chamber. The system may also include a plurality of heating elements, with each of the heating elements being associated with one of the plurality of micro-sensors, and the plurality of heating elements being configured to implement a different temperature level at each of the micro-sensors. The system may also include a microprocessor configured to determine a thermodynamic property of the mixture of gaseous fuel at the different temperature levels at each of the micro-sensors as a function of the characteristic sensed by each micro-sensor, correlate the thermodynamic property to a fuel gas composition of the mixture of gaseous fuel, and control an amount of at least one constituent in the mixture of gaseous fuel as a function of the fuel gas composition determined by the correlation.