SU1647407A1 - Semiconductor hot-wire anemometer - Google Patents

Abstract

The invention relates to a measurement technique and can be used to measure small gas flow rates. The purpose of the invention is to increase the sensitivity. The sensing element 1, made in the form of a conical filamentous single crystal of tellurium doped with silver concentration

Description

figure 1

This invention relates to instrumentation engineering and can be used to measure air flow rates.

The aim of the invention is to increase the sensitivity.

Figure 1 shows the scheme of the hot-wire anemometer; 2 - its calibration characteristic.

A semiconductor thermo-anemometer contains sensitive elements 1, contacts 2, current leads 3. Overheating of sensitive element 1 is carried out from a stabilized DC source A. The voltage drop across the sensing element 1 is measured with a digital measuring device 5, the current through the sample is measured by a 6-meter 6. The sensing element is fixed on the ring holder 7.

The parameters of the sensitive element 1 (single-crystal single crystal tellurium doped with silver with a concentration of (07-1.3) 10 at.%, Are as follows: specific resistivity - 0.4 Ohm cm, total resistance 100-200 Ohm, length 3-4 mm, average diameter 150-200 microns, taper dR / cl -5%.

Semiconductor thermo-anemometer is made as follows.

To the sensitive element 1, an electric pulse welding of the gold microwire creates contacts 2, which are simultaneously the current leads 3. The sensitive element 1 with the pin 3 are installed in the middle of the fluoroplastic holder 4.

Current source 5 and meters 6 and 7 are also available.

Semiconductor thermo-anemometer works as follows.

The sensing element 1 is connected to the measuring circuit containing a stabilized constant current source 5, digital measuring devices 6 and 7, using connecting wires, contacts 2 and leads 3, the ring holder 4 is installed at the exit of the quartz tube, through which air is blown through a certain speed and temperature. Experimentally select the overheating current of the sensing element (10-16 mA), which provides high sensitivity and the required operating temperature range (for example, 20 + 50 ° С). Construct the calibration curve A (V), where AU Uv-U0 (the difference between the voltage drop across the sensing element in the presence of flow and in its absence). The flow temperature is determined by

the same sensitive element 1 in the thermistor mode. The resulting calibration curve is shown in Figure 2 for room temperature and MA.

Then, using the specified calibration curve, an unknown flow rate is determined. In this case, the hot-wire anemometer with a holder 4 is positioned either directly in the test stream or at its outlet.

Claims (1)

Invention Formula A semiconductor thermo-anemometer containing a sensitive element made of tellurium single crystal, contacts and current leads characterized by In order to increase the sensitivity, the tellurium single crystal is made in the form of a cone with a taper of 5% and doped with silver with a concentration (07, -4 1.3) Yu chat.%. 200 i i i II 0 W FIG. 2