It is known that the medium in the pipeline is nitrogen, with an inlet pressure of 0.4 MPa (absolute) and an outlet pressure of 0.1 MPa (absolute), at a temperature of 25°C...
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Given that the medium flowing in the pipeline is nitrogen, with an inlet pressure of 0.4 MPa (absolute), an outlet pressure of 0.1 MPa (absolute), and a temperature of 25°C, how can the flow velocity of nitrogen within the pipeline be calculated? For the flow of compressible fluids, if the change in absolute pressure between two cross-sections of the system is greater than 20% of the original absolute pressure – that is, >20% of P1 (the absolute pressure before the cross-section) to P2 (the absolute pressure after the cross-section) – then the Bernoulli equation cannot be used. So how should the calculation be carried out?
I recommend that you take a look at HG 20570.7 regarding the calculations related to compressible fluids
Um, um, let me take a look, thank you
Hello, I have taken a look at the standards. I believe my operating condition falls under critical flow conditions, but I’m not sure how to determine this. The calculation formulas require the flow velocity of the medium inside the pipeline, and that’s exactly what I need to know. . .
I recommend that you take a look at the section on \"Pipe diameters for compressible fluid pipelines\" in \"Part 1: Design and Calculation of Process Piping Installation in Petrochemical Plants\"; the information there is consistent, and the manual explains it more clearly. First, determine the initial pipe diameter: (1) Calculate the gas mass flow rate based on the desired Mach number value; (2) Determine the minimum allowable pipe diameter using the calculated gas mass flow rate; (3) Round this minimum value to the nearest standard pipe size to obtain a preliminary pipe diameter. The final pipe diameter is then determined by applying the formulas provided in standards or manuals to this preliminary diameter. If the resulting value meets the requirements, it becomes the final pipe diameter; otherwise, a larger diameter is chosen and the calculation is repeated. Finally, the flow velocity is calculated based on the final determined pipe diameter