Compressor - Semi-Empirical Model¶

Model description¶

The model is based on the semi-empirical model proposed by Lemort (2008) for scroll compressors.

Class description¶

class component.compressor.compressor_semi_empirical.CompressorSE[source]¶

Component: Volumetric compressor

Model: The model is based on the thesis of V. Lemort (2008) and is a semi-empirical model

Descritpion:

This model is used to simulate the performance of a volumetric compressor. It has already been used to model scroll and screw compressors. The parameters of the model need to be calibrated with experimental datas to represent the real behavior of the compressor.

Assumptions:

Steady-state operation.

Connectors:

su (MassConnector): Mass connector for the suction side.

ex (MassConnector): Mass connector for the exhaust side.

W (WorkConnector): Work connector.

Q_amb (HeatConnector): Heat connector for the ambient heat transfer.

Parameters:

AU_amb: Heat transfer coefficient for the ambient heat transfer. [W/K]

AU_su_n: Nominal heat transfer coefficient for the suction side heat transfer. [W/K]

AU_ex_n: Nominal heat transfer coefficient for the exhaust side heat transfer. [W/K]

d_ex: Pressure drop diameter. [m]

m_dot_n: Nominal mass flow rate. [kg/s]

A_leak: Leakage area. [m^2]

W_dot_loss_0: Constant loss in the compressor. [W]

alpha: Loss coefficient. [-]

C_loss: Torque losses. [N.m]

rv_in: Inlet volume ratio. [-]

V_s: Swept volume. [m^3]

Inputs:

P_su: Suction side pressure. [Pa]

T_su: Suction side temperature. [K]

P_ex: Exhaust side pressure. [Pa]

fluid: Suction side fluid. [-]

N_rot: Rotational speed [rpm] or m_dot: Mass flow rate [kg/s]

T_amb: Ambient temperature. [K]

Ouputs:

eta_is: Isentropic efficiency. [-]

h_ex: Exhaust side specific enthalpy. [J/kg]

T_ex: Exhaust side temperature. [K]

W_dot_cp: Compressor power. [W]

m_dot: Mass flow rate [kg/s] or N_rot: Rotational speed [rpm]

epsilon_v: Volumetric efficiency. [-]

Notes:

The parameter ‘mode’ can be set to ‘N_rot’ or ‘m_dot’. If ‘N_rot’ is selected, the rotational speed of the compressor is given as an input and the mass flow rate is calculated. If ‘m_dot’ is selected, the mass flow rate is given as an input and the rotational speed of the compressor is calculated.

Example of use¶

from labothappy.component.compressor.compressor_semi_empirical import CompressorSE

"Example of the semi-empirical model compressor component"
# Inputs: N_rot, T_amb, P_su, h_su, P_ex, fluid 
#         OR m_dot, T_amb, P_su, h_su, P_ex, fluid
# Parameters: AU_amb, AU_su_n, AU_ex_n, d_su1, m_dot_n, A_leak, W_dot_loss_0, alpha, C_loss, 
# rv_in, V_s, mode

# Create an instance of the expander component
compressor = CompressorSE()

#-------------------------------------------------------------------------------------------#
"First case: m_dot known and N_rot unknown"
#-------------------------------------------------------------------------------------------#
# "Specify m_dot as an input"
compressor.set_parameters(
    AU_amb=9.96513290e+00, AU_su_n=1.02359773e+01, AU_ex_n=2.24133147e+00, d_ex=1.82304791e-02, m_dot_n=0.1, 
    A_leak=3.66336680e-07, W_dot_loss_0=9.05482168e-01, alpha=3.22395090e-03, C_loss=1.11169710e-061, rv_in=1.7,
    V_s=1.17889079e-04, mode = 'm_dot'
)

# "1. Inputs set through connectors"
# # Set properties for su connector
# compressor.su.set_properties(P=319296.5575177148, T=331.033964665788, m_dot=0.2, fluid='R1233zd(E)')
# compressor.ex.set_properties(P=606240.1433176235)

# # Set ambient temperature
# compressor.Q_amb.set_T_cold(293)


# "2. Inputs set directly"
# compressor.set_inputs(
#     # N_rot=6000,
#     m_dot=0.2,
#     T_amb=293,
#     P_su=319296.5575177148,
#     T_su=331.033964665788,
#     P_ex=606240.1433176235,
#     fluid='R1233ZDE'  # Make sure to include fluid information
# )

#-------------------------------------------------------------------------------------------#
"Second case: N_rot known and m_dot unknown"
#-------------------------------------------------------------------------------------------#
"Specify N_rot as an input"
# compressor.set_parameters(
#     AU_amb=9.96513290e+00, AU_su_n=1.02359773e+01, AU_ex_n=2.24133147e+00, d_ex=1.82304791e-02, m_dot_n=0.1, 
#     A_leak=3.66336680e-07, W_dot_loss_0=9.05482168e-01, alpha=3.22395090e-03, C_loss=1.11169710e-061, rv_in=1.7,
#     V_s=1.17889079e-04, mode = 'N_rot'
# )

"1. Inputs set through connectors"
# Set properties for su connector
compressor.su.set_properties(P=319296.5575177148, T=331.033964665788, m_dot=0.2, fluid='R1233zd(E)')
compressor.ex.set_properties(P=606240.1433176235)

# Set ambient temperature
compressor.Q_amb.set_T_cold(293)

# Set rotational speed
compressor.W.set_N_rot(6000)

#---------------------------------------------------------------------------------------------#
"Solve compressor component"
#---------------------------------------------------------------------------------------------#
# compressor.print_setup()
# Solve the compressor component
compressor.solve()
compressor.print_results()

fig = compressor.plot_Ts()
fig.show()

References¶

Lemort, V. (2008). Contribution to the Characterization of Scroll Machines in Compressor and Expander Modes [Doctoral thesis, ULiège - Université de Liège]. ORBi-University of Liège. https://orbi.uliege.be/handle/2268/135317