# -*- coding: utf-8 -*-
"""
Created on Sun Nov 5 10:01:28 2023
@author: atakan
"""
import numpy as np
import carbatpy as cb
[docs]
def s_irr_flow(states, mass_flow_rates, verbose=False, entropy_position=4):
"""
Irreversible entropy production rate for two fluid flows or an adiabatic
heat exchanger. It is intended to use for heat pumps, where energy is
stored at low and at high temperature.
Parameters
----------
states : numpy-array [n,2,7]
the states to analyse ordered as entering fluids[:,0,:] and exiting
fluid [:,1,:] the states are as defined in fluid_props, with the 4th
value being the specific entropy in J/(kg K)(see below).
mass_flow_rates : numpy array of length n
the mass flow rates in SI units (kg/s).
verbose : Boolean, optional
should we print? The default is False.
entropy_position : Integer, optional
in the states array, where to find thge specific entropy.
The default is 4.
Returns
-------
float
entropy production rate in W/K.
"""
# state in always first
s_irr = (
-(states[:, 0, entropy_position] - states[:, 1, entropy_position])
* mass_flow_rates
)
if verbose:
print("Sirr:", s_irr, states[:, :, n_pos], mass_flow_rates, s_irr.sum())
return s_irr.sum()
[docs]
def exergy_loss_alternative(
states,
mass_flow_rates,
power_in=0.0,
temp_surrounding=cb._T_SURROUNDING,
verbose=False,
entropy_position=4,
enthaply_position=2,
):
"""
assumption both fluids enter in equilibrium with the surrounding
if entropy is reduced, T is below the environment T and exergy is positive
but this not correct yet, should be implemented correctly
"""
ds = states[:, 0, entropy_position] - states[:, 1, entropy_position]
dh = states[:, 0, enthaply_position] - states[:, 1, enthaply_position]
dex = (dh - ds * temp_surrounding) * mass_flow_rates
if verbose:
print(
"Ex-Alt:",
dh * mass_flow_rates,
ds * mass_flow_rates,
mass_flow_rates,
dex,
power_in,
)
print("in:", states[:, 0, n_pos])
print("out:", states[:, 1, n_pos])
print("dex", dex)
dex_total = power_in + np.sum(dex)
return dex_total # must be checked, if more than two streams are analyzed
[docs]
def exergy_loss_flow(
states,
mass_flow_rates,
power_in=0.0,
temp_surrounding=cb._T_SURROUNDING,
verbose=False,
entropy_position=4,
):
"""
Calculate the exergy loss rate for two fluid flows or an adiabatic
heat exchanger. It is intended to use for heat pumps, where energy is
stored at low and at high temperature. Uses s_irr_flow. All parameters are
described there, except one. Gouy-Stodola
Parameters
----------
states : TYPE
DESCRIPTION.
mass_flow_rates : TYPE
DESCRIPTION.
power_in : TYPE, optional
DESCRIPTION. The default is 0..
temp_surrounding : Float, optional
surrounding temperature in K. The default is cb._T_SURROUNDING.
verbose : TYPE, optional
DESCRIPTION. The default is False.
entropy_position : TYPE, optional
DESCRIPTION. The default is 4.
Returns
-------
float
Exergy loss rate in W.
"""
s_irr = s_irr_flow(
states, mass_flow_rates, verbose=verbose, entropy_position=entropy_position
)
return s_irr * temp_surrounding # + power_in
if __name__ == "__main__":
[docs]
FLUID = "Propane * Pentane"
comp = [0.50, 0.5]
P_OUT = 5e5
power = 15000.00
m_dots = np.array((1.4, 1)) # important different signs
flm = cb.fprop.FluidModel(FLUID)
myFluid = cb.fprop.Fluid(flm, comp)
state_in = myFluid.set_state([320.0, 19e5], "TP")
state_out = myFluid.set_state([300, 19e5], "TP")
state_in_2 = myFluid.set_state([290.0, 19e5], "TP")
h2o = state_in_2[2] + (m_dots[0] * (state_in - state_out)[2] + power) / m_dots[1]
state_out_2 = myFluid.set_state([h2o, 19e5], "HP")
print(
"States\n",
state_in[n_pos],
state_out[n_pos],
state_in_2[n_pos],
state_out_2[n_pos],
h2o,
m_dots,
)
states = np.array([[state_in, state_out], [state_in_2, state_out_2]])
print(
"Irr-Gouy-Stod1\n",
s_irr_flow(states, m_dots),
exergy_loss_flow(states, m_dots, power_in=power),
)
print("Ex_loss2\n", exergy_loss_alternative(states, m_dots, power_in=power))