Gas flow sensor system and method of self-calibration

A method for determining gas mass flow rate through a gas passageway, comprising:

• i) providing a gas flow sensor system which comprises:
• a) a sensor interface/control module;
• b) a temperature sensor for measuring the temperature of a gas, electrically connected to the sensor interface/control module;
• and
• c) a gas flow sensor, electrically connected to the sensor interface/control module;
• the sensor interface/control module comprising a microcontroller for monitoring the temperature of a gas as measured by the temperature sensor, and for adjusting the temperature of the gas flow sensor to a predefined differential temperature compared to the temperature of gas as measured by the temperature sensor;
• ii) measuring the temperature of a gas flowing through a gas passageway by means of the temperature sensor;
• iii) monitoring the temperature of gas as measured by the temperature sensor, via the microcontroller of the sensor interface/control module;
• and
• iv) adjusting the temperature of the gas flow sensor to a predefined differential temperature compared to the temperature of gas as measured by the temperature sensor via the microcontroller of the sensor interface/control module.

A method for self-calibration of a gas flow sensor system which comprises:

• i) providing a gas flow sensor system which comprises:
• a) a sensor interface/control module;
• b) a temperature sensor for measuring the temperature of a gas, electrically connected to the sensor interface/control module;
• and
• c) a gas flow sensor having a heat transfer coefficient having an initial value, electrically connected to the sensor interface/control module;
• the sensor interface/control module comprising a microcontroller for monitoring the temperature of a gas as measured by the temperature sensor, and for adjusting the temperature of the gas flow sensor to a predefined differential temperature compared to the temperature of gas as measured by the temperature sensor;
• ii) measuring the temperature of a gas flowing through a gas passageway by means of the temperature sensor;
• iii) monitoring the temperature of gas as measured by the temperature sensor, via the microcontroller of the sensor interface/control module;
• iv) adjusting the temperature of the gas flow sensor to a predefined differential temperature compared to the temperature of gas as measured by the temperature sensor via the microcontroller of the sensor interface/control module;
• v) determining the power dissipated by the gas flow sensor under conditions where gas is flowing through a gas passageway, with the sensor interface/control module;
• vi) determining the power dissipated by the gas flow sensor under conditions where no gas flows through the gas passageway, using the sensor interface/control module;
• vii) calculating any difference between power dissipated by the gas flow sensor in steps (v) and (vi);
• and
• viii) adjusting the value of the heat transfer coefficient of the gas flow sensor with the sensor interface/control module until power dissipation of the gas flow sensor is substantially equal under conditions wherein gas is flowing through the gas passageway, and under conditions wherein no gas flows through the gas passageway.