Merge pull request #8577 from NREL/177124326_Issue8567New

Addresses zone air mass flow balance enforcing problem when there is "balanced" exhaust flow

doc/input-output-reference/src/overview/group-fans.tex

@@ -618,7 +618,7 @@ \subsubsection{Inputs}\label{inputs-3-014}
 
 \paragraph{Field: Balanced Exhaust Fraction Schedule Name}\label{field-balanced-exhaust-fraction-schedule-name}
 
-This field is optional. If it is not used, then all the exhaust air flow is assumed to be unbalanced by any simple airflows, such as infiltration, ventilation, or zone mixing. Unbalanced exhaust is then modeled as being provided by the outdoor air system in the central air system. The modeling of unbalanced will reduce the flow rates at the zone's return air node by the flow rate that is being exhausted and will ensure that the outdoor air flow rate is sufficient to serve the exhaust. If this field is used, then enter the name of a schedule with fractional values between 0.0 and 1.0, inclusive. This fraction is applied to the exhaust fan flow rate and the model tracks the portion of the exhaust that is balanced. Balanced exhaust is then modeled as being provided by simple airflows and does not impact the central air system return air or outdoor air flow rates. For example, if a kitchen zone with an exhaust fan is designed to draw half of its make up air from a neighboring dining room and the other half from the outdoor air system, then a schedule value of 0.5 could be used here.
+This field is optional. If it is not used, then all the exhaust air flow is assumed to be unbalanced by any simple airflows, such as infiltration, ventilation, or zone mixing. Unbalanced exhaust is then modeled as being provided by the outdoor air system in the central air system. The modeling of unbalanced will reduce the flow rates at the zone's return air node by the flow rate that is being exhausted and will ensure that the outdoor air flow rate is sufficient to serve the exhaust. If this field is used, then enter the name of a schedule with fractional values between 0.0 and 1.0, inclusive. This fraction is applied to the exhaust fan flow rate and the model tracks the portion of the exhaust that is balanced. Balanced exhaust is then modeled as being provided by simple airflows and does not impact the central air system return air or outdoor air flow rates. For example, if a kitchen zone with an exhaust fan is designed to draw half of its make up air from a neighboring dining room and the other half from the outdoor air system, then a schedule value of 0.5 could be used here. This input field must be blank when the zone air flow balance is enforced. If user specifies a schedule and zone air flow balance is enforced, then EnergyPlus throws a warning error message, ignores the schedule and simulation continues.   
 
 \subsubsection{Outputs}\label{outputs-3-007}
 

src/EnergyPlus/DataHeatBalance.hh

@@ -1054,10 +1054,13 @@ namespace DataHeatBalance {
                                      // AdjustReturnThenMixing, None)
         int InfiltrationTreatment;   // determines how infiltration is treated for zone mass balance
         int InfiltrationZoneType;    // specifies which types of zones allow infiltration to be changed
+        bool AdjustZoneMixingFlow; // used to adjust zone mixing air flows to enforce air flow balance
+        bool AdjustZoneInfiltrationFlow; // used to adjust zone infiltration air flows to enforce air flow balance
                                      // Note, unique global object
 
         // Default Constructor
-        ZoneAirMassFlowConservation() : EnforceZoneMassBalance(false), ZoneFlowAdjustment(0), InfiltrationTreatment(0), InfiltrationZoneType(0)
+        ZoneAirMassFlowConservation()
+            : EnforceZoneMassBalance(false), ZoneFlowAdjustment(0), InfiltrationTreatment(0), InfiltrationZoneType(0), AdjustZoneMixingFlow(false), AdjustZoneInfiltrationFlow(false)
         {
         }
     };
@@ -1075,6 +1078,7 @@ namespace DataHeatBalance {
         int NumSourceZonesMixingObject;        // number of zone mixing object references as a source zone
         int NumReceivingZonesMixingObject;     // number of zone mixing object references as a receiving zone
         bool IsOnlySourceZone;                 // true only if used only as a source zone in zone mixing object
+        bool IsSourceAndReceivingZone;         // true only if a zone is used as a source and receiving zone in zone mixing objects
         int InfiltrationPtr;                   // pointer to infiltration object
         Real64 InfiltrationMassFlowRate;       // infiltration added to enforced source zone mass balance, kg/s
         int IncludeInfilToZoneMassBal;         // not self-balanced, include infiltration in zone air mass balance
@@ -1086,7 +1090,7 @@ namespace DataHeatBalance {
         // Default Constructor
         ZoneMassConservationData()
             : ZonePtr(0), InMassFlowRate(0.0), ExhMassFlowRate(0.0), RetMassFlowRate(0.0), MixingMassFlowRate(0.0), MixingSourceMassFlowRate(0.0),
-              NumSourceZonesMixingObject(0), NumReceivingZonesMixingObject(0), IsOnlySourceZone(false), InfiltrationPtr(0),
+              NumSourceZonesMixingObject(0), NumReceivingZonesMixingObject(0), IsOnlySourceZone(false), IsSourceAndReceivingZone(false), InfiltrationPtr(0),
               InfiltrationMassFlowRate(0.0), IncludeInfilToZoneMassBal(0)
         {
         }

src/EnergyPlus/Fans.cc

@@ -59,6 +59,7 @@
 #include <EnergyPlus/Data/EnergyPlusData.hh>
 #include <EnergyPlus/DataContaminantBalance.hh>
 #include <EnergyPlus/DataEnvironment.hh>
+#include <EnergyPlus/DataHeatBalance.hh>
 #include <EnergyPlus/DataLoopNode.hh>
 #include <EnergyPlus/DataPrecisionGlobals.hh>
 #include <EnergyPlus/DataSizing.hh>
@@ -591,18 +592,31 @@ namespace EnergyPlus::Fans {
             }
 
             if (NumAlphas > 8 && !lAlphaFieldBlanks(9)) {
-                Fan(FanNum).BalancedFractSchedNum = GetScheduleIndex(state, cAlphaArgs(9));
-                if (Fan(FanNum).BalancedFractSchedNum == 0) {
-                    ShowSevereError(state, RoutineName + cCurrentModuleObject + ": invalid " + cAlphaFieldNames(9) + " entered =" + cAlphaArgs(9) + " for " +
-                                    cAlphaFieldNames(1) + '=' + cAlphaArgs(1));
-                    ErrorsFound = true;
-                } else if (Fan(FanNum).BalancedFractSchedNum > 0) {
-                    if (!CheckScheduleValueMinMax(state, Fan(FanNum).BalancedFractSchedNum, ">=", 0.0, "<=", 1.0)) {
-                        ShowSevereError(state, RoutineName + cCurrentModuleObject + ": invalid " + cAlphaFieldNames(9) + " for " + cAlphaFieldNames(1) +
-                                        '=' + cAlphaArgs(1));
-                        ShowContinueError(state, "Error found in " + cAlphaFieldNames(9) + " = " + cAlphaArgs(9));
-                        ShowContinueError(state, "Schedule values must be (>=0., <=1.)");
+
+                if (state.dataHeatBal->ZoneAirMassFlow.ZoneFlowAdjustment != DataHeatBalance::NoAdjustReturnAndMixing) {
+                    // do not include adjusted for "balanced" exhaust flow in the zone total return calculation
+                    ShowWarningError(state,
+                                     RoutineName + cCurrentModuleObject + ": invalid " + cAlphaFieldNames(9) + " = " + cAlphaArgs(9) +
+                                         " for " + cAlphaFieldNames(1) + '=' + cAlphaArgs(1));
+                    ShowContinueError(state, "When zone air mass flow balance is enforced, this input field should be left blank.");
+                    ShowContinueError(state, "This schedule will be ignored in the simulation.");
+                    Fan(FanNum).BalancedFractSchedNum = 0;
+                } else {
+                    Fan(FanNum).BalancedFractSchedNum = GetScheduleIndex(state, cAlphaArgs(9));
+                    if (Fan(FanNum).BalancedFractSchedNum == 0) {
+                        ShowSevereError(state,
+                                        RoutineName + cCurrentModuleObject + ": invalid " + cAlphaFieldNames(9) + " entered =" + cAlphaArgs(9) +
+                                            " for " + cAlphaFieldNames(1) + '=' + cAlphaArgs(1));
                         ErrorsFound = true;
+                    } else if (Fan(FanNum).BalancedFractSchedNum > 0) {
+                        if (!CheckScheduleValueMinMax(state, Fan(FanNum).BalancedFractSchedNum, ">=", 0.0, "<=", 1.0)) {
+                            ShowSevereError(state,
+                                            RoutineName + cCurrentModuleObject + ": invalid " + cAlphaFieldNames(9) + " for " + cAlphaFieldNames(1) +
+                                                '=' + cAlphaArgs(1));
+                            ShowContinueError(state, "Error found in " + cAlphaFieldNames(9) + " = " + cAlphaArgs(9));
+                            ShowContinueError(state, "Schedule values must be (>=0., <=1.)");
+                            ErrorsFound = true;
+                        }
                     }
                 }
             } else {

src/EnergyPlus/HeatBalanceAirManager.cc

@@ -2715,6 +2715,10 @@ namespace EnergyPlus::HeatBalanceAirManager {
                         state.dataHeatBal->MassConservation(ZoneNum).ZoneMixingReceivingPtr(Loop) = ZoneMixingNum(Loop);
                     }
                 }
+                // flag zones used as both source and receiving zone
+                if (state.dataHeatBal->MassConservation(ZoneNum).NumSourceZonesMixingObject > 0 && state.dataHeatBal->MassConservation(ZoneNum).NumReceivingZonesMixingObject > 0) {
+                    state.dataHeatBal->MassConservation(ZoneNum).IsSourceAndReceivingZone = true;
+                }
             }
             if (allocated(ZoneMixingNum)) ZoneMixingNum.deallocate();
         }
@@ -2723,7 +2727,13 @@ namespace EnergyPlus::HeatBalanceAirManager {
         // and then proceeds to source zones
         Loop = 0;
         for (ZoneNum = 1; ZoneNum <= state.dataGlobal->NumOfZones; ++ZoneNum) {
-            if (!state.dataHeatBal->MassConservation(ZoneNum).IsOnlySourceZone) {
+            if (!state.dataHeatBal->MassConservation(ZoneNum).IsOnlySourceZone && !state.dataHeatBal->MassConservation(ZoneNum).IsSourceAndReceivingZone) {
+                Loop += 1;
+                state.dataHeatBalFanSys->ZoneReOrder(Loop) = ZoneNum;
+            }
+        }
+        for (ZoneNum = 1; ZoneNum <= state.dataGlobal->NumOfZones; ++ZoneNum) {
+            if (state.dataHeatBal->MassConservation(ZoneNum).IsSourceAndReceivingZone) {
                 Loop += 1;
                 state.dataHeatBalFanSys->ZoneReOrder(Loop) = ZoneNum;
             }
@@ -2734,7 +2744,6 @@ namespace EnergyPlus::HeatBalanceAirManager {
                 state.dataHeatBalFanSys->ZoneReOrder(Loop) = ZoneNum;
             }
         }
-
         cCurrentModuleObject = "ZoneCrossMixing";
         int inputCrossMixing = inputProcessor->getNumObjectsFound(state, cCurrentModuleObject);
         state.dataHeatBal->TotCrossMixing = inputCrossMixing + state.dataHeatBal->NumAirBoundaryMixing;
@@ -3754,7 +3763,7 @@ namespace EnergyPlus::HeatBalanceAirManager {
             // Check for infiltration in zone which are only a mixing source zone
             for (ZoneNum = 1; ZoneNum <= state.dataGlobal->NumOfZones; ++ZoneNum) {
                 if ((state.dataHeatBal->ZoneAirMassFlow.ZoneFlowAdjustment != DataHeatBalance::NoAdjustReturnAndMixing && state.dataHeatBal->MassConservation(ZoneNum).IsOnlySourceZone) &&
-                    (state.dataHeatBal->ZoneAirMassFlow.InfiltrationTreatment != NoInfiltrationFlow)) {
+                    (state.dataHeatBal->ZoneAirMassFlow.InfiltrationTreatment != DataHeatBalance::NoInfiltrationFlow)) {
                     if (state.dataHeatBal->MassConservation(ZoneNum).InfiltrationPtr == 0) {
                         ShowSevereError(state, RoutineName + ": Infiltration object is not defined for zone = " + state.dataHeatBal->Zone(ZoneNum).Name);
                         ShowContinueError(state, "Zone air mass flow balance requires infiltration object for source zones of mixing objects");

src/EnergyPlus/HeatBalanceManager.cc

@@ -1246,6 +1246,7 @@ namespace HeatBalanceManager {
                         ShowWarningError(state, CurrentModuleObject + ": Invalid input of " + cAlphaFieldNames(1) + ". The default choice is assigned = None");
                     }
                 }
+                if (state.dataHeatBal->ZoneAirMassFlow.ZoneFlowAdjustment != DataHeatBalance::NoAdjustReturnAndMixing) state.dataHeatBal->ZoneAirMassFlow.AdjustZoneMixingFlow = true;
             }
             if (NumAlpha > 1) {
                 {
@@ -1303,6 +1304,7 @@ namespace HeatBalanceManager {
         } else {
             state.dataHeatBal->ZoneAirMassFlow.EnforceZoneMassBalance = false;
         }
+        if (state.dataHeatBal->ZoneAirMassFlow.InfiltrationTreatment != DataHeatBalance::NoInfiltrationFlow) state.dataHeatBal->ZoneAirMassFlow.AdjustZoneInfiltrationFlow = true;
 
         constexpr const char * Format_732(
             "! <Zone Air Mass Flow Balance Simulation>, Enforce Mass Balance, Adjust Zone Mixing and Return {{AdjustMixingOnly | AdjustReturnOnly | AdjustMixingThenReturn | AdjustReturnThenMixing | None}}, Adjust Zone Infiltration "

src/EnergyPlus/SimulationManager.cc

@@ -3086,7 +3086,7 @@ void Resimulate(EnergyPlusData &state,
         // HVAC simulation
         ManageZoneAirUpdates(state, iGetZoneSetPoints, ZoneTempChange, false, UseZoneTimeStepHistory, 0.0);
         if (state.dataContaminantBalance->Contaminant.SimulateContaminants) ManageZoneContaminanUpdates(state, iGetZoneSetPoints, false, UseZoneTimeStepHistory, 0.0);
-        CalcAirFlowSimple(state, 0, state.dataHeatBal->ZoneAirMassFlow.EnforceZoneMassBalance, state.dataHeatBal->ZoneAirMassFlow.EnforceZoneMassBalance);
+        CalcAirFlowSimple(state, 0, state.dataHeatBal->ZoneAirMassFlow.AdjustZoneMixingFlow, state.dataHeatBal->ZoneAirMassFlow.AdjustZoneInfiltrationFlow);
         ManageZoneAirUpdates(state, iPredictStep, ZoneTempChange, false, UseZoneTimeStepHistory, 0.0);
         if (state.dataContaminantBalance->Contaminant.SimulateContaminants) ManageZoneContaminanUpdates(state, iPredictStep, false, UseZoneTimeStepHistory, 0.0);
         SimHVAC(state);

src/EnergyPlus/VariableSpeedCoils.cc

@@ -7474,8 +7474,8 @@ namespace VariableSpeedCoils {
             //   Calculate apparatus dew point conditions using TotCap and CBF
             Real64 hDelta = TotCapCalc / AirMassFlow;                       // Change in air enthalpy across the cooling coil [J/kg]
             Real64 hADP = InletEnthalpy - hDelta / (1.0 - localCBF);        // Apparatus dew point enthalpy [J/kg]
-            Real64 tADP = PsyTsatFnHPb(state, hADP, Pressure);                     // Apparatus dew point temperature [C]
-            Real64 wADP = PsyWFnTdbH(state, tADP, hADP);                           // Apparatus dew point humidity ratio [kg/kg]
+            Real64 tADP = PsyTsatFnHPb(state, hADP, Pressure, RoutineName); // Apparatus dew point temperature [C]
+            Real64 wADP = PsyWFnTdbH(state, tADP, hADP, RoutineName);       // Apparatus dew point humidity ratio [kg/kg]
             Real64 hTinwADP = PsyHFnTdbW(InletDryBulb, wADP);               // Enthalpy at inlet dry-bulb and wADP [J/kg]
             SHRCalc = min((hTinwADP - hADP) / (InletEnthalpy - hADP), 1.0); // temporary calculated value of SHR
 

src/EnergyPlus/ZoneEquipmentManager.cc

@@ -2622,11 +2622,6 @@ namespace EnergyPlus::ZoneEquipmentManager {
 
         // Determine flow rate and temperature of supply air based on type of damper
 
-        //bool AdjustZoneMassFlowFlag(true); // holds zone mixing and infiltration flow calc status
-
-        bool AdjustZoneMixingFlowFlag(true); // holds zone mixing air flow calc status
-        bool AdjustZoneInfiltrationFlowFlag(true); // holds zone infiltration air flow calc status
-
         FirstCall = true;
         ErrorFlag = false;
 
@@ -2673,11 +2668,12 @@ namespace EnergyPlus::ZoneEquipmentManager {
 
         // Loop over all the primary air loop; simulate their components (equipment)
         // and controllers
-
         if (state.dataHeatBal->ZoneAirMassFlow.EnforceZoneMassBalance) {
-            if (state.dataHeatBal->ZoneAirMassFlow.ZoneFlowAdjustment == DataHeatBalance::NoAdjustReturnAndMixing) AdjustZoneMixingFlowFlag = false;
-            if (state.dataHeatBal->ZoneAirMassFlow.ZoneFlowAdjustment == DataHeatBalance::NoInfiltrationFlow) AdjustZoneInfiltrationFlowFlag = false;
-            CalcAirFlowSimple(state, 0, AdjustZoneMixingFlowFlag, AdjustZoneInfiltrationFlowFlag);
+            if (FirstHVACIteration) {
+                CalcAirFlowSimple(state, 0);
+            } else {
+                CalcAirFlowSimple(state, 0, state.dataHeatBal->ZoneAirMassFlow.AdjustZoneMixingFlow, state.dataHeatBal->ZoneAirMassFlow.AdjustZoneInfiltrationFlow);
+            }
         }
 
         for (ControlledZoneNum = 1; ControlledZoneNum <= state.dataGlobal->NumOfZones; ++ControlledZoneNum) {
@@ -3993,7 +3989,8 @@ namespace EnergyPlus::ZoneEquipmentManager {
 
                 // Calculate standard return air flow rate using default method of inlets minus exhausts adjusted for "balanced" exhaust flow
                 StdTotalReturnMassFlow = TotInletAirMassFlowRate + ZoneMixingNetAirMassFlowRate -
-                                         (TotExhaustAirMassFlowRate - state.dataZoneEquip->ZoneEquipConfig(ZoneNum).ZoneExhBalanced);
+                    (TotExhaustAirMassFlowRate - state.dataZoneEquip->ZoneEquipConfig(ZoneNum).ZoneExhBalanced);
+
                 if (!state.dataHeatBal->ZoneAirMassFlow.EnforceZoneMassBalance) {
                     if (StdTotalReturnMassFlow < 0.0) {
                         state.dataZoneEquip->ZoneEquipConfig(ZoneNum).ExcessZoneExh = -StdTotalReturnMassFlow;