If the flow rate remains unchanged and the pressure decreases, how to calculate the pipe diameter?
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The inlet pressure is 0.5MP, the pipe diameter is DN80, the flow rate remains unchanged at 440m3/h, and the pressure after one diameter change is required to reach 1.5kpa. How to calculate the pipe diameter? The flow rate calculated by the Boer Effort equation is impossible. It exceeds the speed of sound. Is there the possibility of such direct diameter change? If possible, how to calculate it, or how to solve it, thank you
It's ok to use Bernoulli's equation and continuity equation. See fluid mechanics books for details.
A1V1=A2 V2 Q= A1V1 Among them, the diameter of D1 is 80mm and the flow rate is 440m3/h. V1=24.3m/s can be calculated according to the Bernoulli equation p+ρgz+(1/2)* ρv^2=C The medium is air and it is a horizontal pipe. Then you can calculate the flow rate and pipe diameter of D2. P1=0.5MPa, P2=1.5KPa. The flow rate V2 seems to be more than 700 m/s. D2 seems to be more than 13 mm. It requires a diameter change to reduce the pressure. I think it is impossible. I want to ask if it is possible. If calculated according to this, the flow rate is too high and the pipe diameter is too small. It does not meet the requirements. Please call for help.
The medium you are calculating is gas, and the unit should be standard square meter (Nm3/h), right? It may not actually be that big
Urgent, I'm bursting into tears. It's impossible according to my algorithm.
Haha, it's too much to increase the pressure by changing the diameter. Then why do we need a booster pump in the factory? For example, if the compressed air is directly connected to the atmosphere through a pipe, and the high pressure and medium pressure are produced by changing the diameter, how wonderful will it be and how much money will be saved?
This is the gas throttling effect, which is theoretically possible. The volume increases, the temperature decreases, and the pressure decreases.
Although I don’t understand the starting point of the original poster’s calculation, an important issue was obviously ignored in the calculation, that is, air is a compressible fluid. As for the density you gave at different pressures, the density changes greatly. Your data is calculated based on the fact that the air density does not change.
Also, is the pressure mentioned by the poster gauge pressure or absolute pressure? This has a great impact on the air density. If estimated based on the gauge pressure and considering the resistance loss, it is estimated to be 300m/s.