Thermal mass flow meters employ the thermal dispersion principle whereby the rate of heat absorbed by a fluid flowing in a pipe or duct is directly proportional to its mass flow. In a typical thermal flow meter gas flowing over a source of heat absorbs the heat and cools the source.
As flow increases, more heat is absorbed by the gas. The amount of heat dissipated from the heat source is proportional to the gas mass flow and its thermal properties. Therefore, measurement of the heat transfer supplies data from which a mass flow rate may be calculated.
Thermal Mass Flow Meter
Thermal mass flow meters are designed to accurately monitor and measure mass flow (as opposed to measuring volumetric flow) of clean gases, a parameter that is not temperature dependent.
Therefore, the thermal mass flow meter does not require a correction for changes in gas temperature, pressure, viscosity and density.
