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Addressed CoolingTower:VariableSpeed control problems #7702

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merged 14 commits into from
Mar 6, 2020
Merged

Addressed CoolingTower:VariableSpeed control problems #7702

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c9c67ea
addresses VS tower control issue
Jan 22, 2020
6644efa
Merge branch 'develop' into 170845444_Issue7464
Jan 22, 2020
554312b
Merge branch 'develop' into 170845444_Issue7464
Jan 23, 2020
4a86338
added unit test
Jan 24, 2020
4a3254a
Merge branch 'develop' into 170845444_Issue7464
Jan 24, 2020
65ad1c2
Modified unit test and did cleanup.
Jan 24, 2020
4bd3499
modified the fix
Jan 24, 2020
c6f93ee
Merge branch 'develop' into 170845444_Issue7464
Jan 24, 2020
c6d5cc4
Updated I/O Ref
Jan 24, 2020
0edb64d
Merge branch 'develop' into 170845444_Issue7464
Jan 27, 2020
c9d665d
Resolved Develop Merge In Conflict
Feb 28, 2020
595f4f2
Minor documentation change
Mar 6, 2020
a7b1850
Merge branch 'develop' into 170845444_Issue7464
Mar 6, 2020
3d848e7
relaxed VS Cooling Tower range max value
Mar 6, 2020
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4 changes: 4 additions & 0 deletions doc/input-output-reference/src/overview/group-plant-condenser-control.tex
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Expand Up @@ -299,6 +299,10 @@ \subsection{PlantEquipmentOperation:ComponentSetpoint}\label{plantequipmentopera

In addition to load range based control on the plant loop, sequencing the plant components based on the outlet temperature of individual equipment is allowed. This scheme is common to many present-day Energy Management Systems sequencing. In this scheme, the sequencing is done based on the order specified in the control object described below.

However, when sequencing a boiler and a cooling tower to control the heating and cooling set point temperatures of a condenser loop, it is recommended that the boiler and the cooling tower be placed in a parallel configuration. The series configuration of these two equipment, though possible to model them, may result in simultaneous heating and cooling operation when the boiler is ON and the cooling tower operates in free cooling mode, i.e.,
the cooling tower may provide free cooling that could over cool the water below the boiler heating setpoint temperature.


\subsubsection{Inputs}\label{inputs-12-011}

\paragraph{Field: Name}\label{field-name-6-014}
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3 changes: 2 additions & 1 deletion src/EnergyPlus/CondenserLoopTowers.cc
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Expand Up @@ -5291,6 +5291,7 @@ namespace CondenserLoopTowers {
// SUBROUTINE LOCAL VARIABLE DECLARATIONS:
int SolFla; // Flag of solver
Array1D<Real64> Par(4); // Parameter array for regula falsi solver
Real64 const VSTowerMaxRangeTemp(22.2222); // set VS cooling tower range maximum value used for solver

// determine tower outlet water temperature
Par(1) = this->thisTowerNum; // Index to cooling tower
Expand All @@ -5299,7 +5300,7 @@ namespace CondenserLoopTowers {
Par(4) = Twb; // inlet air wet-bulb temperature [C]
Real64 Tr; // range temperature which results in an energy balance
auto f = std::bind(&CoolingTower::residualTr, this, std::placeholders::_1, std::placeholders::_2);
General::SolveRoot(Acc, MaxIte, SolFla, Tr, f, 0.001, towers(this->VSTower).MaxRangeTemp, Par);
General::SolveRoot(Acc, MaxIte, SolFla, Tr, f, 0.001, VSTowerMaxRangeTemp, Par);
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@Nigusse Is this overriding the range for all tower types?
Rather than overriding this here, why not set towers(this->VSTower).MaxRangeTemp up in GetTowerInput, here.

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@Nigusse Nigusse Mar 5, 2020 •
edited

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Yes, the 22.2222 is used for all variable speed cooling towers. I can set it but the default value is used elsewhere to check if the actual tower range is outside the default range. I am concerned to change any curve values that are related the data used to generate the coefficients. And one reason that I chose 22.2222 is that it is the same as the VS York CT so that it does not affect the York Model; otherwise, I experimented with a value higher than that. If you still insist, I will make the changes per your suggestion.

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@Nigusse Nigusse Mar 6, 2020 •
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@mjwitte Below is alternative suggestion for your consideration. First, this change impacts the toolcool VS cooling tower model only; second, this model will be able to check and throw warning if the requested tower range is outside the VS cooltool existing (default) tower range maximum limit.

        VSTowerMaxRangeTemp = towers(this->VSTower).MaxRangeTemp;
        if (this->TowerModelType == CoolToolsXFModel) {
            VSTowerMaxRangeTemp = 22.2222; // this relaxes the solution domain
        }

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Nah, let's leave it like it is. Please push up the doc changes and we'll call this complete.

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Done. Thanks!


Real64 _OutletWaterTemp = this->WaterTemp - Tr;

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