Method and thermal, flow measuring device for determining and/or monitoring at least one variable dependent on at least the chemical composition of a measured medium

A method for determining at least one variable dependent at least on the chemical composition of a measured medium, wherein the measured medium has n components, wherein n is greater than or equal to two, comprising the step of:

• measuring each mole fraction, volume fraction and/or mass fraction of m components of the measured medium, wherein:
• m is smaller than or equal to n minus one;
• mole fractions, volume fractions and/or mass fractions of k components of the measured medium, which are not measured;
• and
• k is equal to n minus m, established in such a manner, that a sum of the mole fractions, volume fractions and/or mass fractions of the n components amounts to one.

A thermal, mass flow, measuring device for determining and/or monitoring flow of a measured medium through a measuring tube, comprising:

• two temperature sensors;
• and
• a control/evaluation unit, wherein:
• said two temperature sensors are arranged in a region of a housing facing the measured medium and are in thermal contact with the measured medium flowing through said measuring tube;
• a first temperature sensor is embodied in a heatable manner;
• a second temperature sensor provides information concerning a current temperature of the measured medium;
• said control/evaluation unit, on basis of a temperature difference between the two temperature sensors and/or on the basis of a heating power supplied to aid first temperature sensor, determines mass flow of the measured medium;
• the thermal, mass flow, measuring device is embodied in such a manner, that a quantitative chemical composition of the measured medium is automatically determinable in the thermal, mass flow, measuring device;
• the respective mole fractions, volume fractions and/or mass fractions of m components of the medium—wherein the measured medium has a total of n components, wherein m is smaller than n—are known to the thermal, mass flow, measuring device;
• and
• the mole fractions, volume fractions and/or mass fractions of the k components of the measured medium which are not known—wherein k is equal to n minus m—are determinable in such a manner, that a sum of the mole fractions, volume fractions and/or mass fractions of the n components amounts to one.