source: trunk/sample/miscellaneous/sample_switcher.mso @ 623

using "types";

Model BallWithSafetyValve
        ATTRIBUTES
        Info = "A fixed volume ball with a safety valve
        for the pressure.";
        
    PARAMETERS
    ValveMode as Switcher(Valid = ["closed", "opened"], Default = "closed");
        R as Real(Unit='J/(K*mol)', Default=8.314472);
        V as volume;
        T as temperature;
        Pout as pressure;
        k as Real(Default=30e-3, Unit='kmol/h/kPa^0.5');

        VARIABLES
        flow_in as flow_mol;
        flow_out as flow_mol;
        P as pressure;
        n as mol;
        
    EQUATIONS

        "Ideal gas relation"
        P*V = n*R*T;
        
        "Mass balance"
        diff(n) = flow_in - flow_out;
        
    switch ValveMode
        case "closed":
                flow_out = 0 * 'mol/h';
                when P > 2*'atm' switchto "opened";

        case "opened":
                flow_out = k*sqrt(P - Pout);
                when P < Pout * 1.1 switchto "closed";
        end
end

FlowSheet BallWithSafetyValveTest
        DEVICES
        ball as BallWithSafetyValve;
        
        SET
        ball.V = 1 * 'l';
        ball.T = 300 * 'K';
        ball.Pout = 1 * 'atm';
        ball.ValveMode = "opened";
        
        SPECIFY
        ball.flow_in = 50 * 'mol/h';
        
        INITIAL
        ball.P = 1.2 * 'atm';
        
        OPTIONS
        TimeStep = 0.05;
        TimeEnd = 10;
end