Heat flow measurement in private household heating systems - is by multiplying fluid flow speed with temp. measured acoustically

摘要

A method and circuit for measuring the flow of heat in fluids flowing through pipes are esp. for water heating equipment in domestic households. They enable very accurate heat flow measurement but prevent fraudulent tampering. The speed of sound and the fluid flow speed (v) are measured. The temp. (T) of the fluid is determined from the characteristic relation between temp. and the speed of sound for the partic. fluid. The temp. and flow speed proportional parameters are multiplied together (17). The transition times (th,tr) of a sound wave along a measurement path (A) with and against the flow are measured, their reciprocals differenced and linear combined with one of the reciprocals to produce the speed of sound value (c).