The use of electronic prediction to achieve fast response from a simple thermal mass flow meter

Lilley, P.; Warne, D H; Mordecai, B A; Spencer, A. J. M.

doi:10.1088/0022-3735/8/1/001

Cited by 3 publications

(3 citation statements)

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“…Many companies also advertise performance of their digital flow meters yet details of their instruments are kept as trade secrets. One of the attempts to speed up the response time of conventional flow meters is by electronic prediction as described in [25] published in 1975. There are academic papers on predictive control throughout the 1980s and 1990s.…”

Section: Recent Technologies On Flow Metersmentioning

confidence: 99%

Adaptive Measurement Control of a Thermal Flow Sensor

Yiu¹

2021

Preprint

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In the present work, an adaptive gain switching control strategy and a digital temperature compensation technique are integrated with a hot-thermistor anemometer to achieve sensor speed and accuracy improvement. The limitation of the Wheatstone bridge technique for temperature thermistors is compensated to achieve accuracy improvement. The feedback control gains are adapted to the particular range of airflow rates to achieve faster response. Simulation results have confirmed the response speed and accuracy improvement with the proposed digital sensor system. The proposed design has been implemented, and experiments have been conducted. Compared to an original thermal flow sensor with analog circuit, the measurement speed is significantly improved at low airflow rates with adaptive feedback control gains implemented in the prototype digital sensor system. The developed digital sensor system possesses desirable features such as a direct interface to the computer through a serial port, easy change of operational parameters and sensor configurations, and energy conservation, as well as simpler control design with the use of Pulse Width Modulation (PWM) to control the probe heater power.

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Section: Recent Technologies On Flow Metersmentioning

confidence: 99%

Adaptive Measurement Control of a Thermal Flow Sensor

Yiu¹

2021

Preprint

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“…1.49a, the values of R and C have to be chosen in such a way that RC matches the thermal time-constant of the absolute radiometer, while for circuit 1.49b, RC should equal twice the thermal time-constant of the radiometer (Lilley et al, 1975). The circuit in Fig.…”

Section: Response-accelerating Techniquesmentioning

confidence: 99%

“…Three examples of response-accelerating circuits. (Brinkworth and Hughes, 1975;Lilley et al, 1975) Many detector elements, however, do not show the same frequency response as the simple RC filter with lumped parameters, which has as its signature a high-frequency asymptotic slope of -20 dB/decade ( Fig. 1.48b).…”

Section: Response-accelerating Techniquesmentioning

confidence: 99%