# Evaporation of Ammonia

 User Name Remember Me Password
 Register Blogs Members List Search Today's Posts Mark Forums Read

December 26, 2022, 10:27
Evaporation of Ammonia
#1
New Member

Rahmani Zakaria
Join Date: Dec 2022
Posts: 4
Rep Power: 2
Hi everyone, I am trying to simulate the evaporation of Ammonia (Nh3). A tube-in-tube evaporator was designed for this simulation with 2 inlets and an outlet, where ammonia liquid enters the expansion chamber and mixing with hydrogen. I choose the mixture model with 3 phases as multiphase model upon the details providing by Ansys theory guide.

Primary phase: Hydrogen
Secondary phase: Ammonia-Liquid
Secondary phase: Ammonia-Vapor
Tsat of ammonia @1bar = -33C
P_total = 25bar

Boundary conditions:
Nh3 inlet: Velocity inelt 1m/s, T= -33C
H2 inlet: Velocity inlet 5m/s, T=-5C
mixture outlet: Outflow
Wall: Convection: 20 W/m^2.K, T=10C

Time step size: t=0.0001s
Number of time steps: 250
Max iterations/time step: 10

My questions:
- where should I add the total pressure of the mixture: the operating pressure or the gauge pressure?
- the total pressure is P_tot = 25bar, when ammonia become in contact with hydrogen it is supposed to reduce its partial pressure to P_Nh3 = 1bar and T= -33 C and allow ammonia to evaporate according to the Dalton's law.
the question Ansys will do that?
- I have also a problem with the convergence, there is a fluctuation in residuals then the solution diverges. Then I change the time from transient to steady, the fluctuations do not appear but the residuals still constant and the solution diverge after 60 iterations.
More details in attachments, thanks in advance.
Attached Images
 0.jpg (68.7 KB, 5 views) 7.PNG (30.2 KB, 3 views) 9.jpg (75.3 KB, 2 views) 10.png (42.1 KB, 3 views) 11.PNG (22.9 KB, 1 views)

 Tags convergance, evaporation model, mixture model, partial pressure

 Thread Tools Search this Thread Search this Thread: Advanced Search Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are Off Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Jack0210Jack Fluent UDF and Scheme Programming 8 April 1, 2021 08:16 Jack0210Jack Fluent UDF and Scheme Programming 17 March 31, 2021 13:17 sunggun1212 FLUENT 3 January 11, 2020 04:12 brbbhatti OpenFOAM 11 June 16, 2014 09:40 Jinx CFX 3 January 28, 2010 16:31

All times are GMT -4. The time now is 11:49.

 Contact Us - CFD Online - Privacy Statement - Top