Hi,
   Is this forum still active? I anybody know the answer to the above question?

thanks

Hi, I want to know if a model can be inversed in modelica. (here inverse means: if in causal statement y= x +a; x and a are input and y is output; but if i want to find x as output and y and a as input, the model is called reversed/inversed model) For example, if i have compressor with input air port and output air port, and port has variables associated with it are pressure(P), temperature(T) and mass flow rate(mdot). I have simple steady state model containing three equations as follow:
1. OutPort.mdot = InPort.mdot
2. OutPort.P = rc * InPort.P
3. OutPort.T  =  InPort.T * (1 + rc[ (gamma-1)/gamma) - 1][/sup] / eta);


Here, rc, gamma and eta are compression ratio, ratio of specific heat capacitites and efficiency of compressor.
I want to kwow, if i know values of : gamma, eta ,OutPort.mdot, OutPort.P and OutPort.T and InPort.P and InPort.T, can i find the value of rc.
Can i find values of rc and how should be the model of compressor with above equation.

Thanks

Hi,
     I was modelling thermal- fluid system. I was trying to model it with a connector having one flow variable(mass flow rate) and one effort variable(temperature). As these effort and flow variables are not compatible to each other( I mean normally, for mass flow rate(flow var) the effort variable used is pressure). But in my system i don't want to model pressure related variables. My question is is it possible if I create such connector and add equations in a model?.
    I tried to model a system as mentioned above. But I am getting a structurally singular system.
     I just want to know is it ok if I model a connector with different effort and flow variables other than conventional one?
     Please reply to my post. Thanks in advance....

Hi,
    Thank you very much for your instant reply. I will start working on compressor thing first. I think, your reply is very helpfull to go further in the modeling these components.
     Thank you very much......

regards,
yoga

Hi,
     Thanks for your reply.
     But I am new to this equation based modeling. I am confused about the exact equations required. For example motor drives the compressor. Then for motor, I need current supply and then this drive is given to compressor in terms of torque. But how to get those equations to capture the physics. And if I want to generalize the compressor componenet. I want to drive the compressor by turbine. Actually I am confused. I am not getting where to start. My aim is to find the motor power required for compressor in compression.
     I think my reply is not to the point. This may be because I am not aware of the modeling in modelica.
     

Thanks and regards,
Yoga

Hi,
      I have just started using Modelica. I have created above components using my own connectors and algebraic equations for those components. Now, I want to model these components in details to capture the physics behind it. I am not able to get where to start and what kind of equations for these components will work for these things. At the end I need to connect all the components to simulate refrigeration cycle. Could anyone give me some idea about getting the equations behind the compoenets and using it in modelica model(with proper connectors)?

      Thanks in advance..

regards,
yoga

Dear SKD,
                   Thank you very much.

Hi,
     I have just started using Modelica language. I was creating model using this language based on algebric equations. I am not interested in dynamics of the model. and only wanted to calculate pressure and temp at the inlet and exit of the each of the component. So, I decided to reduce simulation time lets have algebric equations and connector with only pressure and temperature(as I am having algebric equations in the form of temperature and pressure). But I am sure that I can use connector with pressure and temperature only. Can I make such connector and use it in my model.
     Please reply ASAP.
Thanks