1.Changing the thermophysical properties of gases: Changes in fluid temperature can alter the thermophysical properties of gases, such as thermal conductivity and specific heat capacity. Generally speaking, as the temperature increases, the thermal conductivity of the gas increases, and the specific heat capacity also changes. This means that under the same heating power, the ability of gas to absorb and transfer heat changes. According to the working principle of a thermal gas mass flowmeter, changes in the thermal physical properties of the gas can cause changes in the temperature difference detected by the sensor, which in turn affects the mass flow rate results calculated based on the temperature difference. For example, when the gas temperature is higher than the calibration temperature, due to the increase in thermal conductivity, the speed at which the gas carries away heat increases, and the temperature difference detected by the sensor will decrease. If the calculation model under the calibration temperature is still followed, it will result in a smaller measured mass flow rate value.
2.Impact on sensor performance: The sensor of a thermal gas mass flowmeter usually has a certain adaptability range to temperature. When the fluid temperature exceeds this range, the performance of the sensor may be affected. On the one hand, excessive temperature may accelerate the aging and even damage of the heating element of the sensor, leading to unstable heating power and affecting measurement accuracy. On the other hand, temperature changes may cause changes in the sensitivity of temperature sensors. For example, in low-temperature environments, the response speed of temperature sensors may slow down, making it difficult to detect changes in gas temperature in a timely and accurate manner, resulting in measurement errors.
3.Causing thermal expansion of pipelines: Large diameter pipelines undergo thermal expansion or contraction when temperature changes. This may change the flow state of gas inside the pipeline, such as causing local deformation of the pipeline, resulting in uneven airflow distribution, or causing slight changes in the installation position of the flow meter, affecting the accurate measurement of gas flow rate by the sensor. In addition, thermal expansion of pipelines may also subject flow meters to additional stress, affecting their internal structure and the normal operation of sensors, ultimately leading to a decrease in measurement accuracy.
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