Pressure loss in hot fluid. question
Pressure loss in hot fluid. question
(OP)
I wonder what would happen if i begin pumping a saturated liquid on a pipeline with huge friction loss?.
Because in my Hypothetical design i´m pumping saturated liquid Ammonia and i have like 70 bar of friction preassure drop.
Thank you!
Because in my Hypothetical design i´m pumping saturated liquid Ammonia and i have like 70 bar of friction preassure drop.
Thank you!





RE: Pressure loss in hot fluid. question
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RE: Pressure loss in hot fluid. question
Good luck,
Latexman
RE: Pressure loss in hot fluid. question
RE: Pressure loss in hot fluid. question
Thank you for your answer.
Sorry, your right, i'll give more details.
In our system we are cooling an exothermic reaction in a batch reactor, so we put 300 meter coil inside the reactor where it flows SATURATED liquid ammonia -32 °C , 1 bar (refrigeration cycle), but when we calculated the friction loss and is about 70 bar, as a mix of liquid and vapor, so i argue with my college mate that, we have to change the design because so many preassure drop will make liquid change to vapor while flows in the coil, and the efficency of heat exchange will decrease , and he says that this state change to vapor won't happen from friction loss because of the compressor work supplied oppose that change . what´s the truth here?
Thank you.!
RE: Pressure loss in hot fluid. question
I'm assuming you've done some sort of heat transfer calculation which has lead you to the 300m coil to get the necessary surface area, is that correct? If you are using ammonia as the cooling agent (you've stressed it's saturated liquid) then you almost certainly plan on vaporing the ammonia and utilizing the latent heat to cool the reactor? That gives you a flow rate which when you put it through your coil (considering the vapor generated) is generating an unreasonable pressure drop, you need to drop the velocity which means a larger diameter coil or parallel paths or both.
What about a cooling jacket on the outside of the reactor to allow the ammonia to boil and remove the heat?
RE: Pressure loss in hot fluid. question
Exactly ,we did that, this is our first design aproximation, we calculated the Surface area exchange, and we decided to start with a 300 meter, Diameter 1 1/4 BWG 11 single coil to cover that Surface Area. your right , the idea is utilizing the latent heat to cool the reactor, we are going to consider changing the design to what do you suggest, what preassure drop do you think it will be reasonable?.
Thanks for reply, very helpfull.
RE: Pressure loss in hot fluid. question
This is a real world or school design problem?
Good luck,
Latexman
RE: Pressure loss in hot fluid. question
The reaction begins at 25°C (ambient temperature) and we have to cold and maintain it at 5 ° C. We use a TC (temperature controller) to control the ammonia flow.
RE: Pressure loss in hot fluid. question
Good luck,
Latexman
RE: Pressure loss in hot fluid. question
I would like to know what preassure drop would be reasonable in the cooling coil.
I'll try to put more info soon.
Thank you.
RE: Pressure loss in hot fluid. question
I can add something, we don't care the condition of the ammonia in the exit of the coil as long it had utilized completly or most of his latent heat for cooling (idealization).
Sorry for my English, I'm from Argentina =).
RE: Pressure loss in hot fluid. question
"i´m pumping saturated liquid Ammonia and i have like 70 bar of friction preassure drop."
You have 1 bar, but there is 70 bar of friction preassure drop. This is not only unreasonable; it is impossible.
Have you considered a brine circulation cooling loop? Or 50/50 ethylene glycol and water (FP = -30 C). You could chill the brine or EG/water with ammonia refrigeration and then pump it through the RX and back to the chiller - a loop. A total pressure drop (chiller + piping + RX + return piping) of 2-4 bar would be reasonable. in my opinion.
Have you considered using a half-pipe jacketed RX. If you can get enough heat transfer area with a jacket, the RX can be smaller by the volume displaced by the coils you would use.
Just some ideas.
Good luck,
Latexman