The relationship between the gas flow rate measured by a differential pressure flow meter and the density of nitrogen and hydrogen
Thread Content
There is a relationship between the gas flow rate measured by the differential pressure flow meter and the density of the nitrogen-hydrogen mixture. When the density of this mixture increases (i.e., when the nitrogen content is high), the flow rate increases; whereas when the density decreases (i.e., when the nitrogen content is low), the flow rate decreases. This does not conform to the principle that volumetric flow rate is inversely proportional to density in the flow calculation formula. I would appreciate some guidance from experts
I don’t understand what you mean by the traffic formula. q=av, m=p a v.
The flow rate calculation formula is shown in the image; volumetric flow rate and density are inversely proportional. However, in practice, when the nitrogen content is high, the flow rate is higher, while when the nitrogen content is low, the flow rate is lower
This post was last edited by feng*aosa on 2019-6-30 at 19:28. The original poster might have confused different concepts of “traffic”. 1. Volumetric flow rate is independent of density. Volumetric flow rate (Q) = Average flow velocity (v) × Pipe cross-sectional area (A) ； 2. The conversion of volumetric flow rates for different forms of the same medium is only related to density. Flow rate can be expressed in two ways depending on the state of the medium: Actual flow rate: refers to the flow rate under the current conditions of the medium ； Standard flow rate: refers to the flow rate of a medium under specified conditions. For example, for a certain gas with the same mass flow rate, its volumetric flow rate is 1 m3/h under compressed conditions, while at standard conditions (1 atmosphere and 20°C), it may be 10 m3/h. 3. Standard flow rate = Actual flow rate × Density correlation coefficient × Other parameters correlation coefficient; from this relationship, it can be seen that the standard flow rate is proportional to density ； But for flow meters: the direct data they measure is the actual flow rate, and the actual flow rate = standard flow rate / (density correlation coefficient × other parameter correlation coefficients). From this relationship, it can be seen that the actual flow rate is inversely proportional to density. Since the density (temperature and pressure) compensation of flow meters is applied to the direct data measured by the meter, that is, the actual flow rate, the actual flow rate is used when explaining the principle of compensation (flow rate and density are inversely proportional). When a flow meter displays (outputs) the value, it is usually converted to standard flow rate (flow rate is proportional to density). Different textbook authors or flow meter manufacturers use different values of \"flow rate\" when explaining the principles of compensation; some use standard flow rates while others use actual (operational) flow rates. It is essential to be cautious when reading such material, as otherwise it is easy to get confused. Mandarin omits too much in everyday use (phrases like “I’ve eaten”), and expressions related to content, time, questions, answers, etc., are all conveyed beyond just these three characters; this confuses foreigners, and it also poses difficulties for Chinese people when dealing with technical or standardized matters. People who can speak Chinese are all great.
Thank you for your explanation. Could you provide the formulas for calculating standard flow rate and actual flow rate?