Methods and apparatuses for highly sensitive detection of analytes using redox reactions. A library of heat reactions of analytes of interest with a variety of catalysts at a variety of temperatures is prepared. An array of sensors with low thermal mass heating elements is prepared, depositing the same or different catalysts, such as metal oxide catalysts that have multiple oxidation states, on each heating element. The low thermal mass heating elements are preferably not in thermal contact with a substrate, or a low mass substrate is used. The array is exposed to a sample at various temperatures. The sign and magnitude of the heat effect of the redox reaction of compounds in the sample or their decomposition products with each catalyst is measured and compared with the library. The catalysts and temperatures are chosen so that the desired analytes have a unique pattern of heat effect signs and magnitudes when reacted with those catalysts at those temperatures. The resulting detector is highly selective and sensitive to the analytes of interest.

Methods and apparatuses for highly sensitive detection of analytes using redox reactions. A library of heat reactions of analytes of interest with a variety of catalysts at a variety of temperatures is prepared. An array of sensors with low thermal mass heating elements is prepared, depositing the same or different catalysts, such as metal oxide catalysts that have multiple oxidation states, on each heating element. The low thermal mass heating elements are preferably not in thermal contact with a substrate, or a low mass substrate is used. The array is exposed to a sample at various temperatures. The sign and magnitude of the heat effect of the redox reaction of compounds in the sample or their decomposition products with each catalyst is measured and compared with the library. The catalysts and temperatures are chosen so that the desired analytes have a unique pattern of heat effect signs and magnitudes when reacted with those catalysts at those temperatures. The resulting detector is highly selective and sensitive to the analytes of interest.

A method of determining a thermal state or a thermal state transition of a substance based on how much liquid phase is available is disclosed. The method includes: (a) determining a current thermal state of the substance when the internal combustion engine is switched on based on a tank temperature and on a time interval during which the engine is switched off; and (b) calculating a percentage of the liquid phase in case the thermal state is a mixture of solid phase and liquid phase based on a total mass of the substance in the tank, a heat amount supplied to the tank, a heat exchange of the tank with an external environment; and (c) detecting the thermal state transitions based on said tank temperature and its time derivative and on said percentage of the liquid phase.

A composition analysis apparatus for analyzing a composition of a gas includes: a first measurement part measuring concentrations of gases included in a gas to be analyzed; a part calculating converted calorific values, the part including a second measurement part measuring a refractive index of the gas and a speed of a sound propagating through the gas and calculating a converted calorific value of the gas for the refractive index and the sound speed; a part calculating a base miscellaneous gas total error calorific value, the part calculating, based on the converted calorific values, a base error calorific value of an error calorific value attributable to miscellaneous gases included in the gas; and a part calculating a concentration of a first gas not to be measured, the part calculating the concentration of the first gas based on the concentrations of the measured gases and the base error calorific value.

A composition analysis device for fuel gas containing inert gas and flammable gas includes: a heating value measurement device for measuring a heating value per unit amount of the fuel gas; a density measurement device for measuring a density of the fuel gas; and a control device including a composition calculation unit for calculating a composition of the fuel gas using the heating value measured by the heating value measurement device and the density measured by the density measurement device.

A composition analysis device for fuel gas containing inert gas and flammable gas includes: a heating value measurement device for measuring a heating value per unit amount of the fuel gas; a density measurement device for measuring a density of the fuel gas; and a control device including a composition calculation unit for calculating a composition of the fuel gas using the heating value measured by the heating value measurement device and the density measured by the density measurement device.

A composition analysis apparatus for analyzing a composition of a gas includes: a first measurement part measuring concentrations of gases included in a gas to be analyzed; a part calculating converted calorific values, the part including a second measurement part measuring a refractive index of the gas and a speed of a sound propagating through the gas and calculating a converted calorific value of the gas for the refractive index and the sound speed; a part calculating a base miscellaneous gas total error calorific value, the part calculating, based on the converted calorific values, a base error calorific value of an error calorific value attributable to miscellaneous gases included in the gas; and a part calculating a concentration of a first gas not to be measured, the part calculating the concentration of the first gas based on the concentrations of the measured gases and the base error calorific value.

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 fuel gas composition sensing system may include a remotely controllable valve, with the valve including a gas inlet port, a gas outlet port, an internal chamber, and at least one actuating mechanism configured for successively opening the inlet port to allow gas to enter the internal chamber, closing the inlet port and the outlet port to retain the gas in the internal chamber for a period of time, and opening the outlet port to release the gas from the internal chamber. One or more micro-sensors may be mounted in the internal chamber of the valve, with each of the micro-sensors being configured to sense a characteristic of a gas introduced into the internal chamber of the valve. One or more heating elements may be mounted in the internal chamber, with each of the heating elements being associated with one of the one or more micro-sensors, and the one or more heating elements may be configured to implement a different temperature level at each of the micro-sensors in order to enable detection of a resulting change in the characteristic of the gas corresponding to a thermodynamic property of the gas that correlates to a composition of the gas.