Method for thermal flow measurement with non constant heating pulses
US7089804B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 9, 2003 |
| Grant date | Aug 15, 2006 |
| Priority date | — |
| Expiry date | Jan 9, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F1/6986
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The invention relates to a process and a device for thermal measuring the flow rate (v) of a fluid (3). In conventional thermal sensors the heating power P is supplied in the form of rectangular pulses. According to the invention, the sensor means (1b) are supplied by a heating control (2b) with non-constant heating pulses having a sublinear build-up dynamics P(t). Thereby, a nonlinear behaviour of the threshold value time (tS), until a threshold value temperature (Tm) is reached, as a function of the flow rate (v) can at least partially be compensated. Embodiments concern inter alia a build-up dynamics P(t) proportional to tm and/or to a time-independent amplitude factor (1+RS/RI)−1, wherein m is a Reynolds-number-dependent exponent and RS, RI are thermal transfer resistances. The advantages are an improved precision, a shorter measuring time and an enlarged measuring range for the flow rate v.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.