What is a thermal gas mass flowmeter? How does it work?

Next, meter manufacturer Aister instrument to explain what is called a thermal gas mass flowmeter? How does it work?


The thermal gas mass flowmeter is an instrument that uses the basic principle of thermal diffusion to accurately measure the gas flow. The thermal gas mass flowmeter is generally used to measure the small flow of steam, and the sensor is composed of two reference thermal resistors (RTDS). One is the speed sensor RH, and the other is the temperature sensor RMG, which accurately measures the change of gas temperature. When the two RTDS are placed in the vapor body to be measured, during which the RH sensor is heated, another sensor RMG is used to sense the temperature of the gas to be measured. As the gas flow rate increases, the air flow carries more heat, and the temperature of the sensor RH drops.

Summarize
Thermal gas mass flowmeter
According to King's law of thermal effect, heating power P, temperature difference △T (TRH-TRMG) and gas flow Q have a clear mathematical relationship. P/△T=K1+K2f(Q)K3K1, K2, and K3 are constants related to the physical properties of vapors. The accurate measurement method of the mutual temperature difference of the hot gas mass flowmeter overcomes the very large zero drift caused by the water, oil and impurities in the gas when the hot gas mass flowmeter using the basic principle of constant temperature difference is used to accurately measure the gas flow, resulting in the shortcomings of inaccurate measurement. It can also be applied to accurately measure the mass flow of wet steam body, such as real-time detection of gas extraction, exhaust air, exhaust air volume (speed) in the exhaust system under the mine.

Basic working principle

Thermal flowmeter is a flow meter based on the basic principle of thermal diffusion coefficient. That is, when the fluid medium flows through the heat generating object, the heat loss of the heat generating object is proportional to the flow rate of the fluid medium. The sensor of this series of flowmeters has two standard RTDS, one is only used to do the heat source, one is only used to measure the ambient temperature of the fluid medium, when the fluid flows, the temperature difference between the two and the size of the flow into a linear relationship, and then the micro-electronic technology control technology system, the relationship is converted into the linear output of the measurement flow signal.