Fix VRF_FluidTCtrl cooling supply fan power calculation when cycling

src/EnergyPlus/HVACVariableRefrigerantFlow.cc

@@ -283,6 +283,29 @@ void SimulateVRF(EnergyPlusData &state,
         if (state.dataHVACVarRefFlow->VRF(VRFCondenser).CondenserType == DataHeatBalance::RefrigCondenserType::Water)
             UpdateVRFCondenser(state, VRFCondenser);
     }
+    if (state.dataHVACVarRefFlow->VRF(VRFCondenser).VRFAlgorithmType == AlgorithmType::FluidTCtrl) {
+        // consider cycling in fan calculation
+        for (int TUListNum = 1; TUListNum <= state.dataHVACVarRefFlow->NumVRFTULists; ++TUListNum) {
+            auto &thisTUList = state.dataHVACVarRefFlow->TerminalUnitList(TUListNum);
+            for (int TUNum = 1; TUNum <= thisTUList.NumTUInList; ++TUNum) {
+                int heatingCoilNum = state.dataHVACVarRefFlow->VRFTU(TUNum).HeatCoilIndex;
+                int coolingCoilNum = state.dataHVACVarRefFlow->VRFTU(TUNum).CoolCoilIndex;
+                auto &heatingCoil = state.dataDXCoils->DXCoil(heatingCoilNum);
+                auto &coolingCoil = state.dataDXCoils->DXCoil(coolingCoilNum);
+                int fanIndex = state.dataHVACVarRefFlow->VRFTU(TUNum).FanIndex;
+                // only deal with cooling for now. heating RTF might have some issue
+                // does Fan:SystemModel need adjustment as well? if so consider 0-indexing and it's in state.dataHVACFan->fanObjs vector
+                if (fanIndex > 0 && heatingCoil.HeatingCoilRuntimeFraction == 0.0) { // in cooling mode
+                    // here coolingCoil.CoolingCoilRuntimeFraction equals state.dataHVACVarRefFlow->VRF(VRFCond).VRFCondCyclingRatio
+                    // this is not the case for heating
+                    auto &fan = state.dataFans->Fan(fanIndex);
+                    fan.FanPower *= coolingCoil.CoolingCoilRuntimeFraction;
+                    fan.FanEnergy = fan.FanPower * state.dataHVACGlobal->TimeStepSysSec;
+                    fan.PowerLossToAir *= coolingCoil.CoolingCoilRuntimeFraction;
+                }
+            }
+        }
+    }
 }
 
 PlantComponent *VRFCondenserEquipment::factory(EnergyPlusData &state, std::string const &objectName)
@@ -11720,9 +11743,9 @@ void VRFCondenserEquipment::CalcVRFCondenser_FluidTCtrl(EnergyPlusData &state)
 
         // Key outputs of this subroutine
         this->CompActSpeed = max(CompSpdActual, 0.0);
-        this->Ncomp = max(Ncomp, 0.0) / this->EffCompInverter; // 0.95 is the efficiency of the compressor inverter, can come from IDF //@minor
-        this->OUFanPower = this->RatedOUFanPower;              //@ * pow_3( CondFlowRatio )
-        this->VRFCondCyclingRatio = CyclingRatio;              // report variable for cycling rate
+        this->Ncomp = max(Ncomp, 0.0) / this->EffCompInverter;   // 0.95 is the efficiency of the compressor inverter, can come from IDF //@minor
+        this->OUFanPower = this->RatedOUFanPower * CyclingRatio; //@ * pow_3( CondFlowRatio )
+        this->VRFCondCyclingRatio = CyclingRatio;                // report variable for cycling rate
 
         Tdischarge = this->CondensingTemp; // outdoor unit condensing temperature
         this->CoolingCapacity =
@@ -11934,7 +11957,7 @@ void VRFCondenserEquipment::CalcVRFCondenser_FluidTCtrl(EnergyPlusData &state)
         // Key outputs of this subroutine
         this->CompActSpeed = max(CompSpdActual, 0.0);
         this->Ncomp = max(Ncomp, 0.0) / this->EffCompInverter;
-        this->OUFanPower = this->RatedOUFanPower;
+        this->OUFanPower = this->RatedOUFanPower * CyclingRatio;
         this->VRFCondCyclingRatio = CyclingRatio;
 
         Tsuction = this->EvaporatingTemp; // Outdoor unit evaporating temperature

tst/EnergyPlus/unit/HVACVariableRefrigerantFlow.unit.cc

@@ -13192,6 +13192,8 @@ TEST_F(EnergyPlusFixture, VRF_FluidTCtrl_ReportOutputVerificationTest)
     Real64 OAUCoilOutTemp = 0.0;
     bool ZoneEquipment = true;
 
+    // add VRF cycling ratio initialization. Since TU's are simulated first, if there's no initialization, the coil runtime fraction will be zero
+    state->dataHVACVarRefFlow->VRF(1).VRFCondCyclingRatio = 1.0;
     SimulateVRF(*state,
                 state->dataHVACVarRefFlow->VRFTU(VRFTUNum).Name,
                 FirstHVACIteration,
@@ -13219,8 +13221,12 @@ TEST_F(EnergyPlusFixture, VRF_FluidTCtrl_ReportOutputVerificationTest)
     EXPECT_EQ(0.0, thisVRFTU.NoCoolHeatOutAirMassFlow);
     EXPECT_NEAR(5125.0840, thisDXCoolingCoil.TotalCoolingEnergyRate, 0.0001);
     EXPECT_NEAR(4999.8265, thisVRFTU.TotalCoolingRate, 0.0001);
-    EXPECT_NEAR(125.2573, thisFan.FanPower, 0.0001);
+    EXPECT_NEAR(125.2573 * thisDXCoolingCoil.CoolingCoilRuntimeFraction, thisFan.FanPower, 0.0001);
     EXPECT_NEAR(thisDXCoolingCoil.TotalCoolingEnergyRate, (thisVRFTU.TotalCoolingRate + thisFan.FanPower), 0.0001);
+    EXPECT_NEAR(0.8930, state->dataHVACVarRefFlow->VRF(1).VRFCondCyclingRatio, 0.0001);
+    EXPECT_NEAR(state->dataHVACVarRefFlow->VRF(1).OUFanPower,
+                state->dataHVACVarRefFlow->VRF(1).RatedOUFanPower * state->dataHVACVarRefFlow->VRF(1).VRFCondCyclingRatio,
+                0.0001);
 }
 
 // Test for #7648: HREIRFTHeat wrongly used HRCAPFTHeatConst. Occurs only if you have Heat Recovery