Calculation of the height of the U-shaped pipe in the return pipeline
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This post was last edited by Frog of Mount Miaomu on 2019-8-23 17:00 as shown in the picture: The pressure of the evaporator is P1, the pressure in the condenser is P2, and the resistance of the pipeline system is R. Find the calculation formulas of h1 and h2. (I saw the calculations in the standard before and felt that there were some problems and doubts) I hope the master will give you some advice: handshake
As far as your picture is concerned, if we measure the pressure unit according to the height of the liquid column, h2 should be greater than or equal to P1-P2. This can ensure that the liquid flows back into the kettle normally. Second, 2h1 should be greater than P1-P2. This is to ensure that there is enough liquid remaining in the U-shaped tube when the reactor stops steaming and condensing, and that there is enough residual liquid for liquid sealing when starting the next time. In fact, better piping can be done, such as adding a purge valve, etc.
Whether h2 should be greater than P1-P2+hR (pipeline system resistance);
Yes, the purge valve needs to be installed. This picture I drew is mainly for the height issue. The h I refer to in the picture is the height. Is the h you are referring to ρgh?
I think so, what about h1? In addition, h in the picture refers to the height. You are referring to ρgh, right?
It's not h, it's hR, which refers to the pipe resistance drop. As mentioned on the second floor, the unit of pressure is based on the height of the liquid column, which is the height of the liquid column. For specific calculations, the density of the liquid is uniformly converted into the height of the liquid column (or meters). ； h1 See the 2nd floor. Secondly, 2h1 should be greater than P1-P2.
There are many opinions on the Internet, but finally I understand :D
You cannot simply calculate the h1 and h2 heights. There is a big difference between this and the liquid seal. The difference lies in the difference between the condensate flow rate and the pipe diameter, P2-P1. If the pipe diameter is thin, the h2 height needs to be increased. If the pipe diameter is thick, the h2 height can be reduced as much as possible.……
Why is 2h1 supposed to be greater than P1-P2? Isn’t h1 greater than P1-P2? Because by default the U-shaped tube is exactly full of liquid level?