Gas mass flow control method and control calibration device for low Reynolds number region
A gas mass flow, low Reynolds number technology, applied in the direction of flow control using electrical devices, and can solve problems such as easy drift of collected signals
Inactive Publication Date: 2019-06-04
SHANGHAI INST OF MEASUREMENT & TESTING TECH
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Problems solved by technology
The gas mass flow sensor includes thermal insulation diaphragm, heating element, temperature sensor and other devices, all of which are movable parts or loss parts, and the collected signal is also prone to drift
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[0101] The present invention will be further described below in conjunction with accompanying drawing.
[0102] At present, the flow of process gas is mainly controlled by thermal mass flow meter to control the mass flow rate. Such as figure 1 As shown, the thermal mass flowmeter mainly includes a thermal gas flow sensor 1, a flow control component 2, a proportional valve body 3 and a gas flow path 4, etc., as shown in figure 1 shown. Among them, the thermal gas mass flow sensor 1 is a key component of flow control. It uses the principle of heat exchange between the air flow and the heat source, sets the heat source inside, and obtains the mass flow rate of the gas according to the heat change when the gas flows through the heat source.
[0103] The output signal of the thermal gas flow sensor 1 undergoes data processing (including data linearization, temperature compensation, etc.), and adopts closed-loop control technology to realize gas flow control. In the feedback con...
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The invention provides a gas mass flow control method and a control calibration device for a low Reynolds number region. In the low Reynolds number region in which Re is less than or equal to 104, outflow coefficients Cd corresponding to at least 5 different Reynolds numbers Re are calibrated for a critical choked flow element, so as to acquire the functional relationship between the outflow coefficients Cd of the critical choked flow element and the Reynolds numbers Re. Gas flow upstream of the critical choked flow element is kept constant at T0, and gas is allowed to flow through the critical choked flow element and reach a critical choked state. The mass flow of the gas passing through the critical choked flow element is set to be qm. The Reynolds numbers Re and the outflow coefficients Cd are calculated, and the stagnation pressure target value p0 at the inlet of the critical choked flow element is calculated. The inlet pressure of the critical choked flow element is adjusted to p0, and the actual mass flow value of the gas passing through the critical choked flow element is the set value qm. The method and device can provide accurate mass flow for gas equipment, and the device can also be used as a flow calibrator to calibrate an ordinary flow meter.
Description
technical field [0001] The invention relates to the field of low Reynolds number gas mass flow control, in particular to a gas mass flow control method in a low Reynolds number region based on the principle of critical choked flow, a control and calibration device, a control and calibration system, and a control or calibration method. Background technique [0002] Industrial production, process control, medical biology and other fields have higher and higher requirements for gas flow control technology. For example, in the semiconductor manufacturing industry, it is necessary to use precise process gas flow to control the growth of thin films on wafers, which directly affects the yield and productivity of semiconductor chips. In the pharmaceutical industry, wound healing is promoted by controlling the flow of oxygen, and the cultivation of cells or bacteria is controlled by the flow of oxygen or inert gas. Therefore, in order to control the gas flow rate under such working ...
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IPC IPC(8): G05D7/06
Inventor 刘夷平陈超吴锦川李海洋
Owner SHANGHAI INST OF MEASUREMENT & TESTING TECH