Revise OA system fan sizing methodology

NREL · Nov 8, 2024 · b249e6f · b249e6f · nrel-bot-2c · Nov 8, 2024
1 parent 0d248a0
commit b249e6f
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Showing 2 changed files with 2 additions and 10 deletions.
diff --git a/src/EnergyPlus/AirLoopHVACDOAS.cc b/src/EnergyPlus/AirLoopHVACDOAS.cc
@@ -994,13 +994,11 @@ namespace AirLoopHVACDOAS {
         this->GetDesignDayConditions(state);
 
         if (this->m_FanIndex > 0 && this->m_FanTypeNum == SimAirServingZones::CompType::Fan_System_Object) {
-            state.dataFans->fans(this->m_FanIndex)->maxAirFlowRate = sizingMassFlow / state.dataEnvrn->StdRhoAir;
             state.dataLoopNodes->Node(this->m_FanInletNodeNum).MassFlowRateMaxAvail = sizingMassFlow;
             state.dataLoopNodes->Node(this->m_FanOutletNodeNum).MassFlowRateMaxAvail = sizingMassFlow;
             state.dataLoopNodes->Node(this->m_FanOutletNodeNum).MassFlowRateMax = sizingMassFlow;
         }
         if (this->m_FanIndex > 0 && this->m_FanTypeNum == SimAirServingZones::CompType::Fan_ComponentModel) {
-            state.dataFans->fans(this->m_FanIndex)->maxAirFlowRate = sizingMassFlow / state.dataEnvrn->StdRhoAir;
             state.dataFans->fans(this->m_FanIndex)->minAirFlowRate = 0.0;
             state.dataFans->fans(this->m_FanIndex)->maxAirMassFlowRate = sizingMassFlow;
             state.dataLoopNodes->Node(this->m_FanInletNodeNum).MassFlowRateMaxAvail = sizingMassFlow;

diff --git a/src/EnergyPlus/Autosizing/SystemAirFlowSizing.cc b/src/EnergyPlus/Autosizing/SystemAirFlowSizing.cc
@@ -778,14 +778,8 @@ Real64 SystemAirFlowSizer::size(EnergyPlusData &state, Real64 _originalValue, bo
 
                 } else {
                     if (this->curOASysNum > 0) {
-                        if (this->oaSysEqSizing(this->curOASysNum).AirFlow) {
-                            // Parent object sets system flow rate
-                            this->autoSizedValue = this->oaSysEqSizing(this->curOASysNum).AirVolFlow;
-                        } else if (this->oaSysEqSizing(this->curOASysNum).CoolingAirFlow || this->oaSysEqSizing(this->curOASysNum).HeatingAirFlow) {
-                            // Parent object sets heating flow rate
-                            this->autoSizedValue = std::max(this->oaSysEqSizing(this->curOASysNum).CoolingAirVolFlow,
-                                                            this->oaSysEqSizing(this->curOASysNum).HeatingAirVolFlow);
-                        } else if (outsideAirSys(this->curOASysNum).AirLoopDOASNum > -1) {
+                        // should a parent object ever override DOAS or OASystem flow rate (e.g., using oaSysEqSizing().AirVolFlow)?
+                        if (outsideAirSys(this->curOASysNum).AirLoopDOASNum > -1) {
                             this->autoSizedValue =
                                 this->airloopDOAS[outsideAirSys(this->curOASysNum).AirLoopDOASNum].SizingMassFlow / state.dataEnvrn->StdRhoAir;
                         } else {