| 摘要 |
<p>PURPOSE:To measure a flow rate, by measuring the electric power quantity that is consumed to heat up the area of a throttle part of a measuring part to keep a difference between said throttle part and a fluid temperature constant. CONSTITUTION:A fluid flows at a speed v1 through the area having no throttle part of a detector 7 made of a material used for a thermistor, etc., and the fluid temperature of this time point is defined as t1. Thus a heating current flows between heat terminals 5 and 6 to heat the throttle part of the detector 7 up to a surface temperature t2. Furthermore, the difference between temperatures t1 and t2 is kept constant. A throttle part is added to the detector 7 to accelerate the speed of the fluid to v2 from v1, and therefore the quantity of heat absorbed from the surface of the throttle part increases. This meter increases the speed of response and then the accuracy of measurement for a micro flow rate of the liquid. The quantity (EA) of heat absorbed from the throttle surface area is shown as EA=alambdagammav2(t2-t1), where (a) is the throttle surface area, lambda is the heat transmission coefficient and gamma is the specific gravity of the fluid. Then gammav2= KEA is satisfied as long as K=alambda/t2-t1 is satisfied. The weight and the flow rate are obtained from gammav2 as long as the dissipated heat quantity EA is obtained. This quantity EA can be obtained by measuring the electric power consumed for heating.</p> |
