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Fix flow rate issue for fanless unitary system #10825

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Merged
merged 9 commits into from
Feb 4, 2025
Merged

Fix flow rate issue for fanless unitary system #10825

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ca5d09d
If no fan do not touch inlet mass flow rate
mjwitte Nov 19, 2024
bb5da46
undo VS formatting
mjwitte Nov 19, 2024
3cce73c
UnitarySystemModel_MultiSpeedDXCoolCoil_Only_NoFan test
mjwitte Nov 19, 2024
17e34a4
Merge remote-tracking branch 'remotes/origin/develop' into 10823FanFr…
mjwitte Nov 22, 2024
9409ec0
Merge remote-tracking branch 'remotes/origin/develop' into 10823FanFr…
mjwitte Dec 4, 2024
8230692
Merge remote-tracking branch 'remotes/origin/develop' into 10823FanFr…
mjwitte Jan 7, 2025
675350b
Merge remote-tracking branch 'remotes/origin/develop' into 10823FanFr…
mjwitte Jan 21, 2025
8674c6a
Merge remote-tracking branch 'remotes/origin/develop' into 10823FanFr…
mjwitte Jan 23, 2025
17f24af
Unit test Sched repairs
mjwitte Jan 23, 2025
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4 changes: 2 additions & 2 deletions src/EnergyPlus/UnitarySystem.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -887,8 +887,8 @@ namespace UnitarySystems {
this->m_IterationCounter = 0;
std::fill(this->m_IterationMode.begin(), this->m_IterationMode.end(), 0);

// for DX systems, just read the inlet node flow rate and let air loop decide flow
if (this->m_ControlType == UnitarySysCtrlType::Setpoint && this->m_sysType == SysType::Unitary) {
// for systems without a fan, just read the inlet node flow rate and let air loop decide flow
if (this->m_ControlType == UnitarySysCtrlType::Setpoint && this->m_sysType == SysType::Unitary && this->m_FanExists) {
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When using SP control, for airloop equipment the node flow rate is used, for zone equipment the equipment flow rate is used. So my question here is if zone equipment still works with this change. See this at the bottom of UnitarySys::setAverageAirFlow. I;m not sure if there is an example file or unit test for this case.

    if (ScheduleManager::GetCurrentScheduleValue(state, this->m_SysAvailSchedPtr) > 0.0 &&
        ((FanOn || state.dataHVACGlobal->TurnFansOn) && !state.dataHVACGlobal->TurnFansOff)) {
        if (this->m_ControlType == UnitarySysCtrlType::Setpoint) {
            // set point based equipment should use VAV terminal units to set the flow.
            // zone equipment needs to set flow since no other device regulates flow (ZoneHVAC /= AirLoopEquipment)
            if (!this->m_AirLoopEquipment) {

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Maybe just add && this->m_AirLoopEquipment here to cover this? But then zone equipment needs the fan so this looks like it is OK as is.

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We have 2 example files with unitary zone equipment using load control, DOAToUnitarySystem and UnitarySystem_ZoneVSWSHP_wDOAS. Those run fine with no diffs here, as expected since it's load control.

Here's a new one with SP control.
UnitarySystem_ZoneVSWSHP_wDOAS-SPControl.idf.txt
No diffs on this branch for design day and annual.

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Perfect.

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Should we replace UnitarySystem_ZoneVSWSHP_wDOAS with this file? The change to SP control would still meet the zone SP.

image

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Should we replace UnitarySystem_ZoneVSWSHP_wDOAS with this file? The change to SP control would still meet the zone SP.

It should work, but it's not. This is the SP control file, annual, with develop:
image

Since this branch produces the same result, I don't think this should hold up this PR, but it would be nice to figure out how to make this work.

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I'm OK with merging this branch and following up with an issue to correct, or at least investigate,

if (this->m_sysAvailSched->getCurrentVal() > 0.0) {
if (this->m_LastMode == CoolingMode) {
if (this->m_MultiOrVarSpeedCoolCoil) {
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