# -*- coding: utf-8
"""Module of class ParabolicTrough.
This file is part of project TESPy (github.com/oemof/tespy). It's copyrighted
by the contributors recorded in the version control history of the file,
available from its original location
tespy/components/heat_exchangers/parabolic_trough.py
SPDX-License-Identifier: MIT
"""
from tespy.components.component import component_registry
from tespy.components.heat_exchangers.simple import SimpleHeatExchanger
from tespy.tools.data_containers import ComponentProperties as dc_cp
from tespy.tools.data_containers import GroupedComponentProperties as dc_gcp
[docs]
@component_registry
class ParabolicTrough(SimpleHeatExchanger):
r"""
The ParabolicTrough calculates heat output from irradiance.
.. image:: /api/_images/components/ParabolicTrough.svg
:alt: flowsheet of the parabolictrough
:align: center
:class: only-light
.. image:: /api/_images/components/ParabolicTrough_darkmode.svg
:alt: flowsheet of the parabolictrough
:align: center
:class: only-dark
Ports
-----
- Fluid inlets: in1
- Fluid outlets: out1
- Power inlets: heat
- Power outlets: heat
- Heat inlets: heat
- Heat outlets: heat
Mandatory Equations
-------------------
- mass flow equality constraint(s): :py:meth:`variable_equality_structure_matrix <tespy.components.component.Component.variable_equality_structure_matrix>`
- fluid composition equality constraint(s): :py:meth:`variable_equality_structure_matrix <tespy.components.component.Component.variable_equality_structure_matrix>`
When a power or heat connector is attached:
- energy_connector_balance: :py:meth:`energy_connector_balance_func <tespy.components.heat_exchangers.simple.SimpleHeatExchanger.energy_connector_balance_func>`
Parameters
----------
A : float, dict, :code:`"var"`
Area of the parabolic trough. Quantity: :code:`area`. Can be set as a
system variable by passing :code:`"var"` as its value.
aoi : float, dict
Angle of incidence. Quantity: :code:`angle`.
c_1 : float, dict
Thermal loss coefficient 1.
c_2 : float, dict
Thermal loss coefficient 2.
char_warnings : bool
Ignore warnings on default characteristics usage for this component.
D : float, dict, :code:`"var"`
Diameter of channel. Quantity: :code:`length`. Can be set as a system
variable by passing :code:`"var"` as its value.
darcy_group : GroupedComponentProperties
Darcy-Weißbach equation for pressure loss. Elements: :code:`L`,
:code:`ks`, :code:`D`.
Equation: :py:meth:`darcy_func <tespy.components.heat_exchangers.simple.SimpleHeatExchanger.darcy_func>`.
design : list
List containing design parameters (stated as String).
design_path : str
Path to the components design case.
dissipative : bool
Description missing.
doc : float, dict
Degree of cleanliness. Quantity: :code:`ratio`.
dp : float, dict
Inlet to outlet absolute pressure change. Quantity:
:code:`pressure_difference`.
Equation: :py:meth:`dp_structure_matrix <tespy.components.component.Component.dp_structure_matrix>`.
E : float, dict, :code:`"var"`
Solar irradiation to the parabolic trough. Quantity: :code:`heat`. Can
be set as a system variable by passing :code:`"var"` as its value.
energy_group : GroupedComponentProperties
Energy balance equation of the parabolic trough. Elements: :code:`E`,
:code:`eta_opt`, :code:`aoi`, :code:`doc`, :code:`c_1`, :code:`c_2`,
:code:`iam_1`, :code:`iam_2`, :code:`A`, :code:`Tamb`.
Equation: :py:meth:`energy_group_func <tespy.components.heat_exchangers.parabolic_trough.ParabolicTrough.energy_group_func>`.
eta_opt : float, dict
Optical efficiency. Quantity: :code:`efficiency`.
hw_group : GroupedComponentProperties
Hazen-Williams equation for pressure loss. Elements: :code:`L`,
:code:`ks_HW`, :code:`D`.
Equation: :py:meth:`hazen_williams_func <tespy.components.heat_exchangers.simple.SimpleHeatExchanger.hazen_williams_func>`.
iam_1 : float, dict
Incidence angle modifier 1.
iam_2 : float, dict
Incidence angle modifier 2.
ks : float, dict, :code:`"var"`
Roughness of wall material. Quantity: :code:`length`. Can be set as a
system variable by passing :code:`"var"` as its value.
ks_HW : float, dict, :code:`"var"`
Hazen-Williams roughness. Can be set as a system variable by passing
:code:`"var"` as its value.
L : float, dict, :code:`"var"`
Length of channel. Quantity: :code:`length`. Can be set as a system
variable by passing :code:`"var"` as its value.
label : str
The label of the component.
local_design : bool
Treat this component in design mode in an offdesign calculation.
local_offdesign : bool
Treat this component in offdesign mode in a design calculation.
offdesign : list
List containing offdesign parameters (stated as String).
power_connector_location : str
Description missing.
pr : float, dict
Outlet to inlet pressure ratio. Quantity: :code:`ratio`.
Equation: :py:meth:`pr_structure_matrix <tespy.components.component.Component.pr_structure_matrix>`.
printout : bool
Include this component in the network's results printout.
Q : float, dict
Heat transfer. Quantity: :code:`heat`.
Equation: :py:meth:`energy_balance_func <tespy.components.heat_exchangers.simple.SimpleHeatExchanger.energy_balance_func>`.
Q_loss : float, dict
Heat dissipation. Quantity: :code:`heat`.
Tamb : float, dict
Ambient temperature. Quantity: :code:`temperature`.
zeta : float, dict
Deprecated, use :code:`zeta_d4` instead.
zeta_d4 : float, dict
Geometry-independent friction coefficient zeta/D^4 for pressure loss
calculation.
Equation: :py:meth:`zeta_d4_func <tespy.components.component.Component.zeta_d4_func>`.
Example
-------
A parabolic trough is installed using S800 as thermo-fluid.
First, the operation conditions from :cite:`Janotte2014` are reproduced.
Therefore, the direct normal irradiance :math:`\dot{E}_\text{DNI}` is at
1000 :math:`\frac{\text{W}}{\text{m}^2}` at an angle of incidence
:math:`aoi` at 20 °. This means, the direct irradiance to the parabolic
trough :math:`E` is at
:math:`\dot{E}_{DNI} \cdot cos\left(20^\circ\right)`.
>>> from tespy.components import Sink, Source, ParabolicTrough
>>> from tespy.connections import Connection
>>> from tespy.networks import Network
>>> import math
>>> nw = Network(iterinfo=False)
>>> nw.units.set_defaults(**{
... "pressure": "bar", "pressure_difference": "bar",
... "temperature": "degC", "enthalpy": "kJ/kg"
... })
>>> so = Source('source')
>>> si = Sink('sink')
>>> pt = ParabolicTrough('parabolic trough collector')
>>> inc = Connection(so, 'out1', pt, 'in1')
>>> outg = Connection(pt, 'out1', si, 'in1')
>>> nw.add_conns(inc, outg)
The pressure ratio is at a constant level of 1. However, it is possible to
specify the pressure losses from the absorber tube length, roughness and
diameter, too. The aperture surface :math:`A` is specified to 1
:math:`\text{m}^2` for simplicity reasons.
>>> aoi = 20
>>> E = 1000 * math.cos(aoi / 180 * math.pi)
>>> pt.set_attr(
... pr=1, aoi=aoi, doc=1,
... Tamb=20, A=1, eta_opt=0.816, c_1=0.0622, c_2=0.00023, E=E,
... iam_1=-1.59e-3, iam_2=9.77e-5
... )
>>> inc.set_attr(fluid={'INCOMP::S800': 1}, T=220, p=10)
>>> outg.set_attr(T=260)
>>> nw.solve('design')
>>> round(pt.Q.val, 0)
736.0
For example, it is possible to calculate the aperture area of the parabolic
trough given the total heat production, outflow temperature and mass flow.
>>> pt.set_attr(A='var', Q=5e6, Tamb=25)
>>> inc.set_attr(T=None)
>>> outg.set_attr(T=350, m=20)
>>> nw.solve('design')
>>> round(inc.T.val, 0)
229.0
>>> round(pt.A.val, 0)
6862.0
Given this design, it is possible to calculate the outlet temperature as
well as the heat transfer at different operating points.
>>> aoi = 30
>>> E = 800 * math.cos(aoi / 180 * math.pi)
>>> pt.set_attr(A=pt.A.val, aoi=aoi, Q=None, E=E)
>>> inc.set_attr(T=150)
>>> outg.set_attr(T=None)
>>> nw.solve('design')
>>> round(outg.T.val, 0)
244.0
>>> round(pt.Q.val, 0)
3602817.0
"""
[docs]
def get_parameters(self):
data = super().get_parameters()
for k in ["UA_group", "UA_char_group", "UA", "UA_char",
"kA_group", "kA_char_group", "kA", "kA_char", "lmtd"]:
data.pop(k, None)
data.update({
'E': dc_cp(
min_val=0, quantity="heat", _allows_var=True,
description="solar irradiation to the parabolic trough"
),
'A': dc_cp(
min_val=0, quantity="area", _allows_var=True,
description="area of the parabolic trough"
),
'eta_opt': dc_cp(
min_val=0, max_val=1, quantity="efficiency",
description="optical efficiency"
),
'c_1': dc_cp(min_val=0, description="thermal loss coefficient 1"),
'c_2': dc_cp(min_val=0, description="thermal loss coefficient 2"),
'iam_1': dc_cp(description="incidence angle modifier 1"),
'iam_2': dc_cp(description="incidence angle modifier 2"),
'aoi': dc_cp(
min_val=-90, max_val=90, quantity="angle",
description="angle of incidence"
),
'doc': dc_cp(
min_val=0, max_val=1, quantity="ratio",
description="degree of cleanliness"
),
'Q_loss': dc_cp(
max_val=0, _val=0, quantity="heat",
description="heat dissipation",
calc=self._calc_Q_loss, calc_deps=['Q']
),
'energy_group': dc_gcp(
elements=[
'E', 'eta_opt', 'aoi', 'doc', 'c_1', 'c_2', 'iam_1',
'iam_2', 'A', 'Tamb'
],
num_eq_sets=1,
func=self.energy_group_func,
dependents=self.energy_group_dependents,
description="energy balance equation of the parabolic trough"
)
})
return data
[docs]
def energy_group_func(self):
r"""
Equation for solar collector energy balance.
Returns
-------
residual : float
Residual value of equation.
.. math::
\begin{split}
T_m = & \frac{T_{out} + T_{in}}{2}\\
iam = & 1 - iam_1 \cdot |aoi| - iam_2 \cdot aoi^2\\
0 = & \dot{m} \cdot \left( h_{out} - h_{in} \right)\\
& - A \cdot \left[E \cdot \eta_{opt} \cdot doc^{1.5} \cdot
iam \right. \\
& \left. - c_1 \cdot \left(T_m - T_{amb} \right) -
c_2 \cdot \left(T_m - T_{amb}\right)^2
\vphantom{ \eta_{opt} \cdot doc^{1.5}} \right]
\end{split}
Reference: :cite:`Janotte2014`.
"""
i = self.inl[0]
o = self.outl[0]
T_m = 0.5 * (i.calc_T() + o.calc_T())
iam = (
1 - self.iam_1.val_SI * abs(self.aoi.val_SI)
- self.iam_2.val_SI * self.aoi.val_SI ** 2
)
return (
i.m.val_SI * (o.h.val_SI - i.h.val_SI) - self.A.val_SI * (
self.E.val_SI * self.eta_opt.val_SI * self.doc.val_SI ** 1.5 * iam
- self.c_1.val_SI * (T_m - self.Tamb.val_SI)
- self.c_2.val_SI * (T_m - self.Tamb.val_SI) ** 2
)
)
[docs]
def energy_group_dependents(self):
return [
self.inl[0].m,
self.inl[0].p,
self.inl[0].h,
self.outl[0].p,
self.outl[0].h,
] + [self.E, self.A]
[docs]
def convergence_check(self):
pass
def _calc_Q_loss(self):
return -self.E.val_SI * self.A.val_SI + self.Q.val_SI
[docs]
def calc_parameters(self):
r"""Postprocessing parameter calculation."""
super().calc_parameters()
self.Q_loss.is_result = self.energy_group.is_set