def calc_parameters(self):
r"""Postprocessing parameter calculation."""
# component parameters
self.Q.val = self.inl[0].m.val_SI * (
self.outl[0].h.val_SI - self.inl[0].h.val_SI)
self.ttd_u.val = T_bp_p(self.inl[0].get_flow()) - self.outl[1].T.val_SI
self.ttd_l.val = self.outl[0].T.val_SI - self.inl[1].T.val_SI
# pr and zeta
for i in range(2):
self.get_attr('pr' + str(i + 1)).val = (
self.outl[i].p.val_SI / self.inl[i].p.val_SI)
self.get_attr('zeta' + str(i + 1)).val = (
(self.inl[i].p.val_SI - self.outl[i].p.val_SI) * np.pi ** 2 / (
4 * self.inl[i].m.val_SI ** 2 *
(self.inl[i].vol.val_SI + self.outl[i].vol.val_SI)
))
# kA and logarithmic temperature difference
if self.ttd_u.val < 0 or self.ttd_l.val < 0:
self.td_log.val = np.nan
self.kA.val = np.nan
else:
self.td_log.val = ((self.ttd_l.val - self.ttd_u.val) /
np.log(self.ttd_l.val / self.ttd_u.val))
self.kA.val = -self.Q.val / self.td_log.val
def kA_char_func(self):
r"""
Calculate heat transfer from heat transfer coefficient characteristic.
Returns
-------
residual : float
Residual value of equation.
.. math::
0 = \dot{m}_{in,1} \cdot \left( h_{out,1} - h_{in,1}\right) +
kA_{design} \cdot f_{kA} \cdot \frac{T_{out,1} -
T_{in,2} - T_{sat} \left(p_{in,1}\right) + T_{out,2}}
{\ln{\frac{T_{out,1} - T_{in,2}}
{T_{sat} \left(p_{in,1}\right) - T_{out,2}}}}
f_{kA} = \frac{2}{\frac{1}{f_1 \left( expr_1\right)} +
\frac{1}{f_2 \left( expr_2\right)}}
Note
----
For standard functions f\ :subscript:`1` \ and f\ :subscript:`2` \ see
module :py:mod:`tespy.data`.
"""
p1 = self.kA_char1.param
p2 = self.kA_char2.param
f1 = self.get_char_expr(p1, **self.kA_char1.char_params)
f2 = self.get_char_expr(p2, **self.kA_char2.char_params)
i1 = self.inl[0]
i2 = self.inl[1]
o1 = self.outl[0]
o2 = self.outl[1]
# temperature value manipulation for convergence stability
T_i1 = T_bp_p(i1.get_flow())
T_i2 = T_mix_ph(i2.get_flow(), T0=i2.T.val_SI)
T_o1 = T_mix_ph(o1.get_flow(), T0=o1.T.val_SI)
T_o2 = T_mix_ph(o2.get_flow(), T0=o2.T.val_SI)
if T_i1 <= T_o2 and not i1.T.val_set:
T_i1 = T_o2 + 0.5
if T_i1 <= T_o2 and not o2.T.val_set:
T_o2 = T_i1 - 0.5
if T_o1 <= T_i2 and not o1.T.val_set:
T_o1 = T_i2 + 1
if T_o1 <= T_i2 and not i2.T.val_set:
T_i2 = T_o1 - 1
td_log = ((T_o1 - T_i2 - T_i1 + T_o2) /
np.log((T_o1 - T_i2) / (T_i1 - T_o2)))
fkA1 = self.kA_char1.char_func.evaluate(f1)
fkA2 = self.kA_char2.char_func.evaluate(f2)
fkA = 2 / (1 / fkA1 + 1 / fkA2)
return (
i1.m.val_SI * (o1.h.val_SI - i1.h.val_SI) +
self.kA.design * fkA * td_log)
def test_condenser(self):
"""
Test component properties of condenser.
"""
instance = condenser('condenser')
self.setup_heat_exchanger_network(instance)
# design specification
instance.set_attr(pr1=0.98, pr2=0.98, ttd_u=5,
offdesign=['zeta2', 'kA'])
self.c1.set_attr(T=100, p0=0.5, fluid={'Ar': 0, 'H2O': 1})
self.c3.set_attr(T=30, p=5, fluid={'Ar': 0, 'H2O': 1})
self.c4.set_attr(T=40)
instance.set_attr(Q=-80e3)
self.nw.solve('design')
convergence_check(self.nw.lin_dep)
self.nw.save('tmp')
# test heat transfer
Q = self.c1.m.val_SI * (self.c2.h.val_SI - self.c1.h.val_SI)
msg = ('Value ofheat flow be ' + str(round(instance.Q.val, 0)) +
', is ' + str(round(Q, 0)) + '.')
eq_(round(Q, 1), round(instance.Q.val, 1), msg)
# test upper terminal temperature difference. For the component
# condenser the temperature of the condensing fluid is relevant.
ttd_u = round(T_bp_p(self.c1.to_flow()) - self.c4.T.val_SI, 1)
p = round(self.c1.p.val_SI, 5)
kA = instance.kA.val
msg = ('Value of terminal temperature difference must be ' +
str(round(instance.ttd_u.val, 1)) + ', is ' +
str(ttd_u) + '.')
eq_(ttd_u, round(instance.ttd_u.val, 1), msg)
# test lower terminal temperature difference
instance.set_attr(ttd_l=20, ttd_u=np.nan, design=['pr2', 'ttd_l'])
self.nw.solve('design')
convergence_check(self.nw.lin_dep)
msg = ('Value of terminal temperature difference must be ' +
str(instance.ttd_l.val) + ', is ' +
str(self.c2.T.val - self.c3.T.val) + '.')
eq_(round(self.c2.T.val - self.c3.T.val, 1),
round(instance.ttd_l.val, 1), msg)
# check kA value with condensing pressure in offdesign mode:
# no changes to design point means: identical pressure
self.nw.solve('offdesign', design_path='tmp')
convergence_check(self.nw.lin_dep)
msg = ('Value of condensing pressure be ' + str(p) + ', is ' +
str(round(self.c1.p.val_SI, 5)) + '.')
eq_(p, round(self.c1.p.val_SI, 5), msg)
shutil.rmtree('./tmp', ignore_errors=True)
def ttd_u_func(self):
r"""
Equation for upper terminal temperature difference.
Returns
-------
residual : float
Residual value of equation.
.. math::
0 = ttd_{u} - T_{sat} \left(p_{in,1}\right) + T_{out,2}
Note
----
The upper terminal temperature difference ttd_u refers to boiling
temperature at hot side inlet.
"""
T_i1 = T_bp_p(self.inl[0].get_flow())
T_o2 = T_mix_ph(self.outl[1].get_flow(), T0=self.outl[1].T.val_SI)
return self.ttd_u.val - T_i1 + T_o2
def kA_func(self):
r"""
Calculate heat transfer from heat transfer coefficient.
Returns
-------
residual : float
Residual value of equation.
.. math::
0 = \dot{m}_{in,1} \cdot \left( h_{out,1} - h_{in,1}\right) +
kA \cdot \frac{T_{out,1} -
T_{in,2} - T_{sat} \left(p_{in,1}\right) + T_{out,2}}
{\ln{\frac{T_{out,1} - T_{in,2}}
{T_{sat} \left(p_{in,1}\right) - T_{out,2}}}}
"""
i1 = self.inl[0]
i2 = self.inl[1]
o1 = self.outl[0]
o2 = self.outl[1]
T_i1 = T_bp_p(i1.get_flow())
T_i2 = T_mix_ph(i2.get_flow(), T0=i2.T.val_SI)
T_o1 = T_mix_ph(o1.get_flow(), T0=o1.T.val_SI)
T_o2 = T_mix_ph(o2.get_flow(), T0=o2.T.val_SI)
if T_i1 <= T_o2 and not i1.T.val_set:
T_i1 = T_o2 + 0.5
if T_i1 <= T_o2 and not o2.T.val_set:
T_o2 = T_i1 - 0.5
if T_o1 <= T_i2 and not o1.T.val_set:
T_o1 = T_i2 + 1
if T_o1 <= T_i2 and not i2.T.val_set:
T_i2 = T_o1 - 1
td_log = ((T_o1 - T_i2 - T_i1 + T_o2) /
np.log((T_o1 - T_i2) / (T_i1 - T_o2)))
return i1.m.val_SI * (o1.h.val_SI - i1.h.val_SI) + self.kA.val * td_log
def test_Condenser(self):
"""Test component properties of Condenser."""
instance = Condenser('condenser')
self.setup_HeatExchanger_network(instance)
# design specification
instance.set_attr(pr1=0.98, pr2=0.98, ttd_u=5,
offdesign=['zeta2', 'kA_char'])
self.c1.set_attr(T=100, p0=0.5, fluid={'Ar': 0, 'H2O': 1, 'S800': 0})
self.c3.set_attr(T=30, p=5, fluid={'Ar': 0, 'H2O': 1, 'S800': 0})
self.c4.set_attr(T=40)
instance.set_attr(Q=-80e3)
self.nw.solve('design')
convergence_check(self.nw.lin_dep)
self.nw.save('tmp')
Q_design = instance.Q.val
# test specified kA value
instance.set_attr(kA=instance.kA.val * 2 / 3, Q=None)
self.nw.solve('design')
convergence_check(self.nw.lin_dep)
# test heat transfer
Q = self.c1.m.val_SI * (self.c2.h.val_SI - self.c1.h.val_SI)
msg = (
'Value of heat flow must be ' + str(round(Q_design * 2 / 3, 0)) +
', is ' + str(round(Q, 0)) + '.')
assert round(Q, 1) == round(Q_design * 2 / 3, 1), msg
# back to design case
instance.set_attr(kA=None, Q=Q_design)
self.nw.solve('design')
convergence_check(self.nw.lin_dep)
# test heat transfer
Q = self.c1.m.val_SI * (self.c2.h.val_SI - self.c1.h.val_SI)
msg = ('Value of heat flow must be ' + str(round(instance.Q.val, 0)) +
', is ' + str(round(Q, 0)) + '.')
assert round(Q, 1) == round(instance.Q.val, 1), msg
# test upper terminal temperature difference. For the component
# condenser the temperature of the condensing fluid is relevant.
ttd_u = round(T_bp_p(self.c1.get_flow()) - self.c4.T.val_SI, 1)
p = round(self.c1.p.val_SI, 5)
msg = ('Value of terminal temperature difference must be ' +
str(round(instance.ttd_u.val, 1)) + ', is ' +
str(ttd_u) + '.')
assert ttd_u == round(instance.ttd_u.val, 1), msg
# test lower terminal temperature difference
instance.set_attr(ttd_l=20, ttd_u=np.nan, design=['pr2', 'ttd_l'])
self.nw.solve('design')
convergence_check(self.nw.lin_dep)
msg = ('Value of terminal temperature difference must be ' +
str(instance.ttd_l.val) + ', is ' +
str(self.c2.T.val - self.c3.T.val) + '.')
ttd_l_calc = round(self.c2.T.val - self.c3.T.val, 1)
ttd_l = round(instance.ttd_l.val, 1)
assert ttd_l_calc == ttd_l, msg
# check kA value with condensing pressure in offdesign mode:
# no changes to design point means: identical pressure
self.nw.solve('offdesign', design_path='tmp')
convergence_check(self.nw.lin_dep)
msg = ('Value of condensing pressure be ' + str(p) + ', is ' +
str(round(self.c1.p.val_SI, 5)) + '.')
assert p == round(self.c1.p.val_SI, 5), msg
shutil.rmtree('./tmp', ignore_errors=True)
def test_ORCEvaporator(self):
"""Test component properties of orc evaporator."""
# design specification
self.instance.set_attr(pr1=0.95,
pr2=0.975,
pr3=0.975,
design=['pr1', 'pr2', 'pr3'],
offdesign=['zeta1', 'zeta2', 'zeta3'])
self.c1.set_attr(T=146.6,
p=4.34,
m=20.4,
state='g',
fluid={
'water': 1,
'Isopentane': 0
})
self.c3.set_attr(T=146.6, p=10.2, fluid={'water': 1, 'Isopentane': 0})
self.c4.set_attr(T=118.6)
self.c5.set_attr(T=111.6, p=10.8, fluid={'water': 0, 'Isopentane': 1})
# test heat transfer
Q = -6.64e+07
self.instance.set_attr(Q=Q)
self.nw.solve('design')
convergence_check(self.nw.lin_dep)
Q_is = -self.c5.m.val_SI * (self.c6.h.val_SI - self.c5.h.val_SI)
msg = ('Value of heat flow must be ' + str(round(Q, 0)) + ', is ' +
str(round(Q_is, 0)) + '.')
assert round(Q, 0) == round(Q_is, 0), msg
# test bus
self.instance.set_attr(Q=np.nan)
P = -6.64e+07
b = Bus('heat transfer', P=P)
b.add_comps({'comp': self.instance})
self.nw.add_busses(b)
self.nw.solve('design')
convergence_check(self.nw.lin_dep)
self.nw.save('tmp')
Q_is = -self.c5.m.val_SI * (self.c6.h.val_SI - self.c5.h.val_SI)
msg = ('Value of heat flow must be ' + str(round(P, 0)) + ', is ' +
str(round(Q_is, 0)) + '.')
assert round(P, 0) == round(Q_is, 0), msg
# Check the state of the steam and working fluid outlet:
x_outl1_calc = self.c2.x.val
x_outl3_calc = self.c6.x.val
zeta1 = self.instance.zeta1.val
zeta2 = self.instance.zeta2.val
zeta3 = self.instance.zeta3.val
msg = ('Vapor mass fraction of steam outlet must be 0.0, is ' +
str(round(x_outl1_calc, 1)) + '.')
assert round(x_outl1_calc, 1) == 0.0, msg
msg = ('Vapor mass fraction of working fluid outlet must be 1.0, is ' +
str(round(x_outl3_calc, 1)) + '.')
assert round(x_outl3_calc, 1) == 1.0, msg
# Check offdesign by zeta values
# geometry independent friction coefficient
self.nw.solve('offdesign', design_path='tmp')
convergence_check(self.nw.lin_dep)
msg = ('Geometry independent friction coefficient '
'at hot side 1 (steam) '
'must be ' + str(round(zeta1, 1)) + ', is ' +
str(round(self.instance.zeta1.val, 1)) + '.')
assert round(self.instance.zeta1.val, 1) == round(zeta1, 1), msg
msg = ('Geometry independent friction coefficient at '
'hot side 2 (brine) '
'must be ' + str(round(zeta2, 1)) + ', is ' +
str(round(self.instance.zeta2.val, 1)) + '.')
assert round(self.instance.zeta2.val, 1) == round(zeta2, 1), msg
msg = ('Geometry independent friction coefficient at cold side '
'(Isopentane) must be ' + str(round(zeta3, 1)) + ', is ' +
str(round(self.instance.zeta3.val, 1)) + '.')
assert round(self.instance.zeta3.val, 1) == round(zeta3, 1), msg
# test parameters of 'subcooling' and 'overheating'
self.instance.set_attr(subcooling=True, overheating=True)
dT = 0.5
self.c2.set_attr(Td_bp=-dT)
self.c6.set_attr(Td_bp=dT)
self.nw.solve('offdesign', design_path='tmp')
convergence_check(self.nw.lin_dep)
T_steam = T_bp_p(self.c2.get_flow()) - dT
T_isop = T_bp_p(self.c6.get_flow()) + dT
msg = ('Temperature of working fluid outlet must be ' +
str(round(T_isop, 1)) + ', is ' +
str(round(self.c6.T.val_SI, 1)) + '.')
assert round(T_isop, 1) == round(self.c6.T.val_SI, 1), msg
msg = ('Temperature of steam outlet must be ' +
str(round(T_steam, 1)) + ', is ' +
str(round(self.c2.T.val_SI, 1)) + '.')
assert round(T_steam, 1) == round(self.c2.T.val_SI, 1), msg
shutil.rmtree('./tmp', ignore_errors=True)