Temperature versus enthalpy variation is very complicated which makes the simulation difficult.
Using Aspen Plus simulator with the appropriate (NH3-H2O) electrolyte chemistry should get you some reasonable properties. Concentration of the solution, and temperature ranges for the exchanger will be key inputs for defining the heat curve for a given mixture.
It will be eassy if you use EES program( enginerring equation solver).
This way you can even simulate the phase change.
Using Aspen Plus simulator with the appropriate (NH3-H2O) electrolyte chemistry should get you some reasonable properties. Concentration of the solution, and temperature ranges for the exchanger will be key inputs for defining the heat curve for a given mixture.
Dear Rasool,
It seems your problem has not been resolved. Please call me, maybe we can arrange a meeting and discuss your problem in details.
Hi Rasool, what about Refprop? The most common models I know of for estimating the mixutre properties are(1) the equation of state by Ziegler and Trepp, and (2) a formulation based on the Helmholtz free energy by Tillner-Roth and Friend. The first is simpler, you can implement it yourself in e.g. Matlab and the results are satisfactory, other than in the vicinity of the pure fluids (if I remember correctly), i.e., pure water or pure ammonia. The second (2) is more accurate and universal, however, quite complicated and time consuming to implement. If you have the necessary pocket money ;), then you can purchase plug-in's of the model from Professor Kretzschmar from the university of Zittau-Görlitz in Germany for Matlab and Excel. I've tested them and they work greatly. Best regards Mark.
I don't think that ASPEN E-NRTL approach ( suggested by Dave above) can be helpful if your exchanger operates above ammonia critical temperature. You need appropriate EOS as a model of this mixture thermodynamic behaviour. I would suggest to look at papers: FPE, 116 (1996) 170-176; 376 (2014) 141-153. If you are an Aspen user, the appropriate EOS can be implemented as an "user model", and I could help you with this.
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