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dallan-keylogic committed Apr 17, 2024
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99 changes: 46 additions & 53 deletions ...s/model_libraries/power_generation/unit_models/cross_flow_heat_exchanger_1D.rst
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Expand Up @@ -6,7 +6,8 @@ CrossFlowHeatExchanger1D

.. module:: idaes.models_extra.power_generation.unit_models.cross_flow_heat_exchanger_1D

This model is for a cross flow heat exchanger between two gases.
This model is for a cross flow heat exchanger between two gases. The gas in the shell has a straight path,
while the gas in the tubes snakes back and forth across the shell's path.

Example
-------
Expand All @@ -24,12 +25,8 @@ Example
EosType,
)
from idaes.models_extra.power_generation.unit_models import CrossFlowHeatExchanger1D
import idaes.core.util.model_statistics as mstat
from idaes.core.util.model_statistics import degrees_of_freedom
from idaes.core.solvers import get_solver
# Set up solver
optarg = {
"constr_viol_tol": 1e-8,
"nlp_scaling_method": "user-scaling",
Expand All @@ -39,7 +36,6 @@ Example
"tol": 1e-8,
"halt_on_ampl_error": "no",
}
solver = get_solver("ipopt", options=optarg)
m = pyo.ConcreteModel()
m.fs = pyo.FlowsheetBlock(dynamic=False)
Expand Down Expand Up @@ -93,9 +89,9 @@ Example
hx.di_tube.fix(0.0525018)
hx.thickness_tube.fix(0.0039116)
hx.length_tube_seg.fix(4.3)
hx.nseg_tube.fix(12)
hx.ncol_tube.fix(50)
hx.nrow_inlet.fix(25)
hx.number_passes.fix(12)
hx.number_columns_per_pass.fix(50)
hx.number_rows_per_pass.fix(25)
hx.pitch_x.fix(0.1)
hx.pitch_y.fix(0.1)
Expand All @@ -104,9 +100,6 @@ Example
hx.rfouling_shell = 0.0001
hx.fcorrection_htc_tube.fix(1)
hx.fcorrection_htc_shell.fix(1)
if pressure_drop:
hx.fcorrection_dp_tube.fix(1)
hx.fcorrection_dp_shell.fix(1)
hx.cp_wall.value = 502.4
Expand Down Expand Up @@ -141,7 +134,7 @@ Example
iscale.calculate_scaling_factors(m)
initializer = CrossFlowHeatExchanger1DInitializer(
initializer = m.fs.heat_exchanger.default_initializer(
solver="ipopt",
solver_options=optarg
)
Expand All @@ -157,22 +150,26 @@ Variable Index Sets Doc
=========================== =========== =================================================================================
``number_columns_per_pass`` None Number of columns of tube per pass
``number_rows_per_pass`` None Number of rows of tube per pass
``number_passes`` None Number of tube banks of `nrow_tube * ncol_inlet` tubes
``number_passes`` None Number of tube banks of ``nrow_tube * ncol_inlet`` tubes
``pitch_x`` None Distance between columns (TODO rows?) of tubes, measured from center-of-tube to center-of-tube
``pitch_y`` None Distance between rows (TODO columns?) of tubes, measured from center-of-tube to center-of-tube
``length_tube_seg`` None Length of tube segment perpendicular to flow in each pass
``area_flow_shell`` None Reference to flow area on shell control volume
``length_flow_shell`` None Reference to flow length on shell control volume
``area_flow_shell_min`` None Minimum flow area on shell side
``di_tube`` None Inner diameter of tubes
``thickness_tube`` None Thickness of tube wall.
``area_flow_tube`` None Reference to flow area on tube control volume
``length_flow_tube`` None Reference to flow length on tube control volume
=========================== =========== =================================================================================

============================ =========== ===========================================================================
Expression Index Sets Doc
============================ =========== ===========================================================================
``nrow_tube`` None Total number of rows of tube
``do_tube`` None Outer diameter of tube (equal to `di_tube+2*thickness_tube`)
``pitch_x_to_do`` None Ratio of `pitch_x` to `do_tube`
``pitch_y_to_do`` None Ratio of `pitch_y` to `do_tube`
``do_tube`` None Outer diameter of tube (equal to ``di_tube+2*thickness_tube``)
``pitch_x_to_do`` None Ratio of ``pitch_x`` to ``do_tube``
``pitch_y_to_do`` None Ratio of ``pitch_y`` to ``do_tube``
``area_wall_seg`` None Total cross-sectional area of tube per pass
``total_heat_transfer_area`` None Total heat transfer area, as measured on outer surface of tubes
============================ =========== ===========================================================================
Expand All @@ -182,7 +179,7 @@ Constraint Index Sets Doc
=========================== =========== =================================================================================================
``length_flow_shell_eqn`` None Constrains shell flow length from control volume to equal value implied by geometry
``area_flow_shell_eqn`` None Constrains shell flow cross-sectional area from control volume to equal value implied by geometry
``area_flow_shell_min_eqn`` None Constraints `area_flow_shell_min` to equal value determined by geometry
``area_flow_shell_min_eqn`` None Constraints ``area_flow_shell_min`` to equal value determined by geometry
``length_flow_tube_eqn`` None Constrains tube flow length from control volume to equal value implied by geometry
``area_flow_tube_eqn`` None Constrains tube flow cross-sectional area from control volume to equal value implied by geometry
=========================== =========== =================================================================================================
Expand Down Expand Up @@ -214,24 +211,34 @@ Parameter Index Sets Doc
``density_wall`` None Mass density of tube wall metal
``cp_wall`` None Tube wall heat capacity (mass basis)
``rfouling_shell`` None Fouling resistance on shell side
``f_arrangement`` None Adjustment factor depending on `tube_arrangement` in config
``f_arrangement`` None Adjustment factor depending on ``tube_arrangement`` in config
=========================== =========== =================================================================================

====================================== ============ =================================================================================
Constraint Index Sets Doc
====================================== ============ =================================================================================
``v_shell_eqn`` time, length Calculates velocity of flow through shell using `area_flow_shell_min`
``v_shell_eqn`` time, length Calculates velocity of flow through shell using ``area_flow_shell_min``
``N_Re_shell_eqn`` time, length Calculates the shell-side Reynolds number
``conv_heat_transfer_coeff_shell_eqn`` time, length Calculates the shell-side convective heat transfer coefficient
``v_tube_eqn`` time, length Calculates gas velocity in tube
``N_Re_tube_eqn`` time, length Calculates the tube-side Reynolds number
``heat_transfer_coeff_tube_eqn`` time, length Calcualtes the tube-side heat transfer coefficient

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"Calcualtes" should be "Calculates".
``N_Nu_shell_eqn`` time, length Calculate the shell-side Nusselt number
``N_Nu_tube_eqn`` time, length Calculate the tube-side Nusselt number
``heat_tube_eqn`` time, length Calculates heat transfer per unit length
``heat_shell_eqn`` time, length Calculates heat transfer per unit length
``temp_wall_tube_eqn`` time, length Calculate the wall temperature of the inner tube
``temp_wall_shell_eqn`` time, length Calculate the wall temperature of the outer tube
``temp_wall_center_eqn`` time, length Overall energy balance on tube metal
====================================== ============ =================================================================================

====================================== ============ ===================================================================================
Expression Index Sets Doc
====================================== ============ ===================================================================================
``total_heat_transfer_coeff_shell`` time, length Returns ``conv_heat_transfer_coeff_shell``. Could be extended to include radiation.
``total_heat_transfer_coeff_shell`` time Returns ``conv_heat_transfer_coeff_shell``. Could be extended to include radiation.
``total_heat_duty`` time Created only if not ``dynamic``. Gives total heat transferred over entire exchanger
``log_mean_delta_temperature`` time Created only if not ``dynamic``. Gives the log mean temperature difference (LMTD).
``overall_heat_transfer_coefficient`` time Created only if not ``dynamic``. Calculated from total heat transfer, area, and LMTD.
====================================== ============ ===================================================================================

Pressure Change Equations
Expand All @@ -255,21 +262,23 @@ Variable Index Sets Doc
``deltaP_tube_uturn`` time, length Change of pressure in tube due to U turns
=========================== ============ =================================================================================

================================== ============ =================================================================================
================================== ============ ==================================================================================
Constraint Index Sets Doc
================================== ============ =================================================================================
================================== ============ ==================================================================================
``friction_factor_shell_eqn`` time, length Calculates the shell-side friction factor
``deltaP_shell_eqn`` time, length Sets `deltaP_shell` based on the friction factor and shell properties
``deltaP_shell_eqn`` time, length Sets ``deltaP_shell`` based on the friction factor and shell properties
``friction_factor_tube_eqn`` time, length Calculates the tube-side friction factor
``deltaP_tube_friction_eqn`` time, length Sets `deltaP_tube_friction` based on friction factor
``deltaP_tube_uturn_eqn`` time, length Sets `deltaP_tube_uturn` based on `kloss_uturn`
``deltaP_tube_eqn`` time, length Sets `deltaP_tube` by summing `deltaP_tube_friction` and `deltaP_tube_uturn`
================================== ============ =================================================================================
``deltaP_tube_friction_eqn`` time, length Sets ``deltaP_tube_friction`` based on friction factor
``deltaP_tube_uturn_eqn`` time, length Sets ``deltaP_tube_uturn`` based on ``kloss_uturn``
``deltaP_tube_eqn`` time, length Sets ``deltaP_tube`` by summing ``deltaP_tube_friction`` and ``deltaP_tube_uturn``
================================== ============ ==================================================================================


Holdup Equations
----------------
Created when `has_holdup=True` in the config.

Created when ``has_holdup=True`` in the config.

=========================== ============ =================================================================================
Variable Index Sets Doc
=========================== ============ =================================================================================
Expand All @@ -284,35 +293,19 @@ Constraint Index Sets Doc

Dynamic Equations
-----------------
Created when `dynamic=True` in the config.

Created when ``dynamic=True`` in the config.

=========================== ============ =================================================================================
Derivative Variable Index Sets Doc
=========================== ============ =================================================================================
``heat_accumulation`` time, length Energy accumulation in tube wall per unit length of shell flow path per unit time
=========================== ============ =================================================================================


Constraints
-----------

The pressure flow relation is added to the inherited constraints from the :ref:`PressureChanger model
<reference_guides/model_libraries/generic/unit_models/pressure_changer:Pressure Changer>`.

If the ``phase`` option is set to ``"Liq"`` the following equation describes the pressure-flow relation.

.. math::
\frac{1}{s_f^2}F^2 = \frac{1}{s_f^2}C_v^2\left(P_{in} - P_{out}\right)f(x)^2
If the ``phase`` option is set to ``"Vap"`` the following equation describes the pressure-flow relation.

.. math::
\frac{1}{s_f^2}F^2 = \frac{1}{s_f^2}C_v^2\left(P_{in}^2 - P_{out}^2\right)f(x)^2
Initialization
--------------

First, the shell and tube control volumes are initialized without heat transfer. Next
the total possible heat transfer between streams is estimated based on heat capacity,
flow rate, and inlet/outlet temperatures. The actual temperature change is set to be
Expand All @@ -321,14 +314,14 @@ temperature profiles. Finally, temperatures besides the inlets are unfixed and
the performance equations are activated before a full solve of the system model.


HelmValve Class
----------------
CrossFlowHeatExchanger1D Class
------------------------------

.. autoclass:: CrossFlowHeatExchanger1D
:members:

HelmValveData Class
---------------------
CrossFlowHeatExchanger1DData Class
----------------------------------

.. autoclass:: CrossFlowHeatExchanger1DData
:members:
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