clear ;
addpath(genpath('.'))

% Compression ratio & heat recovery efficiency
r = 10 ; % [-]
etaRecovery = 0.8 ; % [-]

% Units
kPa = 1e3 ;    % [Pa]
g   = 1/1000 ; % [kg]
kW  = 1000 ;   % [W]

% Ideal gas, air
gas.Rbar = 8.314 ;            % [J/(mol*K)]
gas.M    = 28.97 * g ;        % [kg/mol]
gas.R    = gas.Rbar / gas.M ; % [J/(kg*K)]

% Constant cp and cv
gas.k  = 1.4 ; % [-]
gas.cv = gas.R / ( gas.k - 1 ) ;
gas.cp = gas.k * gas.cv ;

% States
state1.T = 300 ;       % [K]
state1.p = 100 * kPa ; % [Pa]
state1.v = getVariableFromStateEquation("v", state1, gas) ;

% 1-2 (isoentropic compression)
state2.p = state1.p * r ;
state2   = getStateAfterIsoentropicProcessConst(state1, state2, gas) ;

% 2-3 (p=const)
state3.T = 1400 ; % [K]
state3 = getStateAfterIsobaricProcess(state2, state3, gas) ;

% 3-4 (isoentropic expansion)
state4.p = state1.p ;
state4   = getStateAfterIsoentropicProcessConst(state3, state4, gas) ;

% Determination of hx (after regenerative heat exchange)
deltaH_24 = gas.cp * ( state4.T - state2.T ) ;
deltaH_2x = etaRecovery * deltaH_24 ;
stateX.h  = gas.cp * state2.T + deltaH_2x ;

% Supplied heat [J/kg]
qIn = gas.cp * state3.T - stateX.h ;

% Compression (1-2) & expansion (3-4, turbine) work per unit mass & rlr
lc  = gas.cp * ( state2.T - state1.T ) ;
lt  = gas.cp * ( state3.T - state4.T ) ;

% Thermal efficiency & restitution ratio
eta = (lt - lc) / qIn