PURPOSE: To improve the measuring accuracy of the titled flowmeter, by installing a heater to the outer periphery of a conduit of a multiphase flow and respectively providing temperature measuring sections at the upstream side and downstream side equidistant points from the heater and measuring the temperature difference between the two points, and then, finding the mass flow rate of the fluid flowing through the conduit from the temperature difference and the quantity of heat supplied to the heater.

CONSTITUTION: A heating section 2 of a heater or jacket is installed to the outer periphery of a conduit 1. When the temperature of a solid-gas two phases flow at the upstream side and downstream side of the heating section 2 is respectively expressed as TC1 [°C], TC2 [°C], the mean specific heat of the two phases flow as CP [kcal/kg°C], average temperature difference as ΔTm [°C], heat transfer area as A [m2], general coefficient of heat transfer as U[kcal/ m2h°C], and mass flow rate as G [kg/h], the relation shown by Formula I is obtained. Moreover, when Th2 and Th1 are used to express surface temperatures of the conduit 1, TC2=Th2 and TC1=Th1, because the coefficient of heat transfer and delay in heat transfer are the same at the upstream side and downstream side if the same material is used for making the conduit wall. Namely, the relation shown by Formula II is satisfied and, when the (q) is manipulated to make (Th2-Th1) constant, the G is found.