.. _diso_methods:

Double Inlet - Single Outlet Helper Methods
===========================================

.. index::
   pair: watertap.core.zero_order_diso;build_diso

.. currentmodule:: watertap.core.zero_order_diso

The `build_diso` method is intended to be used to rapidly construct a standard set of material balance equations for zero-order type models with a double inlet and single outlet.

Usage
-----

.. doctest::

  from idaes.core import declare_process_block_class
  from watertap.core import build_diso, ZeroOrderBaseData

  @declare_process_block_class("CofermentationZO")
  class CofermentationZOData(ZeroOrderBaseData):

      CONFIG = ZeroOrderBaseData.CONFIG()

      def build(self):
          super().build()

          self._tech_type = "cofermentation"

          build_diso(self)

Model Structure
---------------

The build_diso method constructs a simple representation of unit operation with two inlets (named `inlet1` and `inlet2`) and one outlet (named `treated`). A `StateBlock` is constructed for each inlet and outlet with a `Port` associated with each of these.

Variables
---------

The build_diso method creates the following variables in addition to those created by the `StateBlocks`.

=============================== ========================= =============== ===============================================================================
Variable                        Name                      Indices         Notes
=============================== ========================= =============== ===============================================================================
:math:`r_{t}`                   recovery_frac_mass_H2O    time            Fraction of mass flow of water in inlet that goes to treated stream.
:math:`f_{t,j}`                 removal_frac_mass_comp    time, component Fraction of mass flow of each component that is removed from the inlet streams.
=============================== ========================= =============== ===============================================================================

recovery_frac_mass_H2O is intended to be fixed to zero (e.g., for reactor that yields solid product at treated outlet) or 1 (e.g., for reactor that yields product stream without water losses), but the user can optionally set this to some fraction.

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

The build_diso method writes the following constraints which relate the inlet states to those in the treated outlet stream.
First, a water recovery equation is written for water to relate the flowrate at the treated outlet to that at the inlet:

`water_recovery_equation(t)`:

.. math:: r_t \times (M_{inlet1,t,H2O} + M_{inlet2,t,H2O}) = M_{treated,t,H2O}

where :math:`M_{t,H2O}` is mass flowrate of water at time :math:`t`.

Note, a mass balance for water is ignored since build_diso is intended to only account for constituent removal/conversion at the treated outlet.
Thus, a mass balance constraint is only written for each solute.

`solute_treated_equation(t, j)`:

.. math:: (1 - f_{t, j}) \times (M_{inlet1,t,j} + M_{inlet2,t,j}) = M_{treated,t,j}

Module Documentation
--------------------

* :mod:`watertap.core.zero_order_diso`