Patent ID: 6883369

Claim:
A non-intrusive sensor for measuring mass flow of a medium flowing through a tube, said sensor comprising: a probe having a predetermined length disposed along an external wall of said tube; means for heating said probe at a first point along the length of said probe; a first temperature measuring device disposed at said first point for measuring a temperature of said probe and for generating a first signal T h representative thereof; a second temperature measuring device disposed at a second point along the length of said probe for measuring another temperature of said probe and for generating a second signal T t representative thereof; a third temperature measuring device disposed along the external wall of said tube a distance away from said probe for measuring an ambient temperature and for generating a signal T a representative thereof; and means coupled to said first, second and third temperature measuring devices for generating a mass flow signal based on a ratio of temperature differential signals (T h −T a )/(T t −T a ).