Hello everybody,

I come today because i've started using dymola a month ago and still cannot start modeling and thought this forum could be a chance to have a better understanding of the problematic. I sincerely hope some of you can enlighten on some of the brought up point (with only one of them explained i'd consider myself already very lucky).

My task consists in modeling a heat pump with all its components (compressor - scroll and swash plate - , heat exchangers and metering device). At the institute we have a test rig with all those components in which we can do some measurements (temperature, pressure). The goal is to obtain those measured values through the simulation with Dymola.

I've starting by reading on modelica (book of Fritzson Peter and understand the way it works, even did some small exercises to get familiar with the environment. I can model/code an electrical circuit, a pendulum without a problem since the equations for those systems are explicit and relatively simple but when it comes to model just the compressor I am a bit lost... Here are the questions where I am not very sure of the answer and whose answers would be very helping for knowing how to proceed.

The VaporCycle library contains all the necessary elements to model the heat pump  (for example the VariableDisplacementTableBased model seem to be suited for a swash plate compressor) but how do I know that those components are adapted in my case ? In other terms what tells me that I shouldnt code the compressor from zero by myself ? Or where should I start (taking a complete modeled component, or extending one).

In the Compressor TableBased model I have to enter a matrix for the efficiencies (volumetric, isentropic, mechanical depending on pressure ratio and compressor speed), I have measured data associated to those required values but I don't know if I must fill the tables with the measured values or the values given by the manufacturer (if they are given).

A very important part are the connectors, and it is said that they are the first things to be created but since in the libraries (Modelon, VaporCycle and Modelon in this case) are compatible in term of connection, what tells me that I should create new and special ones and what should be their particularity ?

The last thing I cannot very good understand is the existing models in the libraries themselves. When using a compressor from two differents libraries, I see the differences through the inputs. But in Modelica the models are based on the variable/parameters and equations and I don't really see those equations. Of course there are the connect equations but I mean in this case the physical equations (for example mass and energy conservation). I thought it's those physical equations which make the differences between each models of the differents libraries but I think I may be wrong on that point.. So my most crucial question is: since I have to model the HP in order to get the results of the test rig, do I first have to find  empirical equations with the measured values (through data ftting on Matlab for example) and then code those equations on Modelica/Dymola or is it possible to get the measured values in simulation with a model built with the existing components in the libraries.

I know this is a lot, but unfortunately I'm the only one using Modelica/Dymola here and this forum is my last chance. I do not expect an answer to each of my questions but If you think you could help me even on a small part of one of this points I would be very, very thankful.

Thank you for your attention

Kevin