Fix VRFFluidCtrl cooling cycling issue by moving cycling ratio calc in compressor spd calc #10353
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
|
|
@@ -266,7 +266,7 @@ void SimulateVRF(EnergyPlusData &state, | |
|
|
||
| if (state.dataHVACVarRefFlow->VRF(VRFCondenser).VRFAlgorithmType == AlgorithmType::FluidTCtrl) { | ||
| // Algorithm Type: VRF model based on physics, applicable for Fluid Temperature Control | ||
| state.dataHVACVarRefFlow->VRF(VRFCondenser).CalcVRFCondenser_FluidTCtrl(state, FirstHVACIteration); | ||
| } else { | ||
| // Algorithm Type: VRF model based on system curve | ||
| CalcVRFCondenser(state, VRFCondenser); | ||
|
|
@@ -11010,7 +11010,7 @@ void VRFTerminalUnitEquipment::CalcVRFIUVariableTeTc(EnergyPlusData &state, | |
| } | ||
| } | ||
|
|
||
| void VRFCondenserEquipment::CalcVRFCondenser_FluidTCtrl(EnergyPlusData &state, const bool FirstHVACIteration) | ||
| { | ||
|
|
||
| // SUBROUTINE INFORMATION: | ||
|
|
@@ -11141,7 +11141,7 @@ void VRFCondenserEquipment::CalcVRFCondenser_FluidTCtrl(EnergyPlusData &state) | |
| Real64 Pipe_DeltP_h; // Piping Loss Algorithm Parameter: Pipe pressure drop (h) [Pa] | ||
| Real64 Pipe_Q_c; // Piping Loss Algorithm Parameter: Heat loss (c) [W] | ||
| Real64 Pipe_Q_h; // Piping Loss Algorithm Parameter: Heat loss (h) [W] | ||
| Real64 Q_c_TU_PL; // Cooling load to be met at cooling mode, including the piping loss(W) | ||
| Real64 Q_h_TU_PL; // Heating load to be met at heating mode, including the piping loss (W) | ||
| Real64 Q_h_OU; // outdoor unit condenser heat release (cooling mode) [W] | ||
| Real64 Q_c_OU; // outdoor unit evaporator heat extract (heating mode) [W] | ||
|
|
@@ -11419,56 +11419,40 @@ void VRFCondenserEquipment::CalcVRFCondenser_FluidTCtrl(EnergyPlusData &state) | |
| C_cap_operation = this->VRFOU_CapModFactor( | ||
| state, h_comp_in, h_IU_evap_in, max(min(Psuction, RefPHigh), RefPLow), Tsuction + SH_Comp, Tsuction + 8, CapMinTc - 5); | ||
|
|
||
| // Iteration_Ncomp: Perform iterations to calculate Ncomp (Label10) | ||
| Counter = 1; | ||
| Ncomp = TU_CoolingLoad / this->CoolingCOP; | ||
| Ncomp_new = Ncomp; | ||
| Label10:; | ||
| Q_h_OU = Q_c_TU_PL + Ncomp_new; // Ncomp_new may be updated during Iteration_Ncomp Label10 | ||
|
|
||
| // *VRF OU TeTc calculations | ||
| m_air = this->OUAirFlowRate * RhoAir; | ||
| SC_OU = this->SC; | ||
| this->VRFOU_TeTc(state, HXOpMode::CondMode, Q_h_OU, SC_OU, m_air, OutdoorDryBulb, OutdoorHumRat, OutdoorPressure, Tfs, this->CondensingTemp); | ||
| this->CondensingTemp = min(CapMaxTc, this->CondensingTemp); | ||
| this->SC = SC_OU; | ||
|
|
||
| // *VEF OU Compressor Simulation at cooling mode: Specify the compressor speed and power consumption | ||
| this->VRFOU_CalcCompC(state, | ||
| TU_CoolingLoad, | ||
| Tsuction, | ||
| this->CondensingTemp, | ||
| Psuction, | ||
| T_comp_in, | ||
| h_comp_in, | ||
| h_IU_evap_in, | ||
| Pipe_Q_c, | ||
| CapMaxTc, | ||
| Q_h_OU, | ||
| CompSpdActual, | ||
| Ncomp, | ||
| CyclingRatio); | ||
|
|
||
| if ((std::abs(Ncomp - Ncomp_new) > (Tolerance * Ncomp_new)) && (Counter < 30)) { | ||
| Ncomp_new = Ncomp; | ||
| Counter = Counter + 1; | ||
| goto Label10; | ||
| } | ||
|
|
||
| // Update h_IU_evap_in in iterations Label12 | ||
|
|
@@ -11490,6 +11474,8 @@ void VRFCondenserEquipment::CalcVRFCondenser_FluidTCtrl(EnergyPlusData &state) | |
| } | ||
|
|
||
| // Key outputs of this subroutine | ||
| Ncomp *= CyclingRatio; | ||
| Q_h_OU *= CyclingRatio; | ||
| 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 ) | ||
|
|
@@ -11975,7 +11961,7 @@ void VRFCondenserEquipment::CalcVRFCondenser_FluidTCtrl(EnergyPlusData &state) | |
|
|
||
| this->HeatingCapacity = 0.0; // Include the piping loss | ||
| this->PipingCorrectionHeating = 1.0; // 1 means no piping loss | ||
| state.dataHVACVarRefFlow->MaxHeatingCapacity(VRFCond) = MaxCap; // default value is MaxCap = 1e+20, not 0 | ||
|
|
||
| this->CoolingCapacity = 0.0; // Include the piping loss | ||
| this->PipingCorrectionCooling = 1.0; | ||
|
|
@@ -12348,6 +12334,25 @@ void VRFCondenserEquipment::CalcVRFCondenser_FluidTCtrl(EnergyPlusData &state) | |
|
|
||
| // Calculate the IU Te/Tc for the next time step | ||
| this->CalcVRFIUTeTc_FluidTCtrl(state); | ||
| // update coil and IU evaporating temperature, also keep coil RTF updated with the condenser side cycling ratio, for the FluidTCtrl model | ||
| for (int VRFTUNum = 1; VRFTUNum <= state.dataHVACVarRefFlow->NumVRFTU; ++VRFTUNum) { | ||
| auto const &thisTU = state.dataHVACVarRefFlow->VRFTU(VRFTUNum); | ||
| auto &coolingCoil = state.dataDXCoils->DXCoil(thisTU.CoolCoilIndex); | ||
| if (this->adjustedTe && (!FirstHVACIteration)) { | ||
| coolingCoil.EvaporatingTemp = this->EvaporatingTemp; | ||
| this->IUEvaporatingTemp = this->EvaporatingTemp; | ||
| } | ||
|
|
||
| int PLF; | ||
| if (coolingCoil.PLFFPLR(1) > 0 && this->VRFCondCyclingRatio < 1.0) { | ||
| PLF = Curve::CurveValue(state, coolingCoil.PLFFPLR(1), this->VRFCondCyclingRatio); // Calculate part-load factor | ||
| } else { | ||
| PLF = 1.0; | ||
| } | ||
| if (coolingCoil.TotalCoolingEnergyRate > 0.0) { | ||
| coolingCoil.CoolingCoilRuntimeFraction = this->VRFCondCyclingRatio / PLF; | ||
| } | ||
|
There was a problem hiding this comment. I don't see CoolingCoilRuntimeFraction getting set to 0 anywhere. So if TotalCoolingEnergyRate = 0, then CoolingCoilRuntimeFraction will be used from the last time step the compressor operated. I would set CoolingCoilRuntimeFraction = 0.0 in Init. There was a problem hiding this comment. It is set to 0 in this function: CalcVRFCoolingCoil_FluidTCtrl There was a problem hiding this comment. Oh, I see. This is updating the coil model RTF, from the parent object. We should not do that. So why did you have to update the coil RTF? VRFCondCyclingRatio is already passed to SimDXCoil so the coil RTF should already be accurate, if that call is passing the updated cycling ratio. There was a problem hiding this comment. The condenser side cycling ratio is updated in |
||
| } | ||
| } | ||
|
|
||
| void VRFTerminalUnitEquipment::ControlVRF_FluidTCtrl(EnergyPlusData &state, | ||
|
|
@@ -13847,14 +13852,16 @@ void VRFCondenserEquipment::VRFOU_CalcCompC(EnergyPlusData &state, | |
| Real64 MaxOutdoorUnitTc, // The maximum temperature that Tc can be at heating mode [C] | ||
| Real64 &OUCondHeatRelease, // Condenser heat release (cooling mode) [W] | ||
| Real64 &CompSpdActual, // Actual compressor running speed [rps] | ||
| Real64 &Ncomp, // Compressor power [W] | ||
| Real64 &CyclingRatio // Cycling Ratio [W] | ||
| ) | ||
| { | ||
|
|
||
| // SUBROUTINE INFORMATION: | ||
| // AUTHOR Xiufeng Pang | ||
| // DATE WRITTEN Feb 2014 | ||
| // MODIFIED Rongpeng Zhang, Jan 2016 | ||
| // MODIFIED Yujie Xu, Sep 2023 | ||
| // RE-ENGINEERED na | ||
|
|
||
| // PURPOSE OF THIS SUBROUTINE: | ||
|
|
@@ -13910,7 +13917,8 @@ void VRFCondenserEquipment::VRFOU_CalcCompC(EnergyPlusData &state, | |
| Real64 RefPHigh; // High Pressure Value for Ps (max in tables) [Pa] | ||
| Real64 T_discharge_new; // Condensing temperature, for temporary use in iterations [C] | ||
| Real64 Tfs; // Temperature of the air at the coil surface [C]] | ||
| Real64 constexpr Tolerance(0.05); // Tolerance for condensing temperature calculation [C] | ||
| Real64 constexpr TeTol(0.5); // Tolerance for the difference between Te and SmallLoadTe | ||
| Array1D<Real64> CompEvaporatingPWRSpd; // Array for the compressor power at certain speed [W] | ||
| Array1D<Real64> CompEvaporatingCAPSpd; // Array for the evaporating capacity at certain speed [W] | ||
|
|
||
|
|
@@ -13939,6 +13947,7 @@ void VRFCondenserEquipment::VRFOU_CalcCompC(EnergyPlusData &state, | |
| C_cap_operation = this->VRFOU_CapModFactor( | ||
| state, Pipe_h_comp_in, Pipe_h_IU_in, max(min(P_suction, RefPHigh), RefPLow), T_suction + Modifi_SH, T_suction + 8, T_discharge - 5); | ||
|
|
||
| this->adjustedTe = false; | ||
| for (CounterCompSpdTemp = 1; CounterCompSpdTemp <= NumOfCompSpdInput; CounterCompSpdTemp++) { | ||
| // Iteration to find the VRF speed that can meet the required load, Iteration DoName1 | ||
|
|
||
|
|
@@ -13987,14 +13996,26 @@ void VRFCondenserEquipment::VRFOU_CalcCompC(EnergyPlusData &state, | |
| MinRefriPe = this->refrig->getSatPressure(state, -15, RoutineName); | ||
| MinOutdoorUnitPe = max(P_discharge - this->CompMaxDeltaP, MinRefriPe); | ||
| MinOutdoorUnitTe = this->refrig->getSatTemperature(state, max(min(MinOutdoorUnitPe, RefPHigh), RefPLow), RoutineName); | ||
| // Te can't be smaller than user input lower bound | ||
| MinOutdoorUnitTe = max(this->IUEvapTempLow, MinOutdoorUnitTe); | ||
|
|
||
| auto f = [&state, T_discharge_new, CondHeat, CAPFT](Real64 const T_suc) { | ||
| return CompResidual_FluidTCtrl(state, T_discharge_new, CondHeat, CAPFT, T_suc); | ||
| }; | ||
|
|
||
| General::SolveRoot(state, 1.0e-3, MaxIter, SolFla, SmallLoadTe, f, MinOutdoorUnitTe, | ||
|
There was a problem hiding this comment. This is poor logic for a SolveRoot failure. -1 means iteration limit exceeded and -2 means it can't find a solution. Using SolFla < 0 captures both and assumes there is a small load. Maybe this works, maybe it doesn't, I don't know. This is a separate issue, if this is actually an issue. There was a problem hiding this comment. I will separate out SolFla=-1 and SolFla=-2 case. When it is -1 I will throw an error message of not reaching convergence. When it is -2, it would be the case where the load is small. In the -2 case, f(MinOutdoorUnitTe) and f(T_suction) can't be both positive as f(T_suction) > 0 would mean , which is If this is the case, it shouldn't have been in |
||
| T_suction); // SmallLoadTe is the updated Te' | ||
| if (SolFla == -1) { | ||
| // show error not converging | ||
| ShowWarningMessage(state, format("{}: low load Te adjustment failed for {}", RoutineName, this->Name)); | ||
| ShowContinueErrorTimeStamp(state, ""); | ||
| ShowContinueError(state, format(" Iteration limit [{}] exceeded in calculating OU evaporating temperature", MaxIter)); | ||
| } else if (SolFla == -2) { | ||
| // demand < capacity at both endpoints of the Te range, assuming f(x) is roughly monotonic than this is the low load case | ||
| assert(f(T_suction) < 0); | ||
| // TeTol is added to prevent the final updated Te to go out of bounds | ||
| SmallLoadTe = 6 + TeTol; // MinOutdoorUnitTe; //SmallLoadTe( Te'_new ) is constant during iterations | ||
| } | ||
|
|
||
| // Get an updated Te corresponding to the updated Te' | ||
| // VRFOU_TeModification( VRFCond, this->EvaporatingTemp, SmallLoadTe, Pipe_h_IU_in, OutdoorDryBulb, Pipe_Te_assumed, | ||
|
|
@@ -14006,6 +14027,7 @@ void VRFCondenserEquipment::VRFOU_CalcCompC(EnergyPlusData &state, | |
| NumIteTe = 1; | ||
| MaxNumIteTe = (this->EvaporatingTemp - SmallLoadTe) / 0.1 + 1; // upper bound and lower bound of Te iterations | ||
| Pipe_Te_assumed = this->EvaporatingTemp - 0.1; | ||
| this->adjustedTe = true; | ||
|
|
||
| Label11:; | ||
| Pipe_m_ref = 0; // Total Ref Flow Rate( kg/s ) | ||
|
|
@@ -14072,14 +14094,14 @@ void VRFCondenserEquipment::VRFOU_CalcCompC(EnergyPlusData &state, | |
|
|
||
| T_suction = this->refrig->getSatTemperature(state, max(min(Pipe_Pe_assumed - Pipe_DeltP, RefPHigh), RefPLow), RoutineName); | ||
|
|
||
| if ((std::abs(T_suction - SmallLoadTe) > TeTol) && (Pipe_Te_assumed < this->EvaporatingTemp) && (Pipe_Te_assumed > SmallLoadTe) && | ||
| (NumIteTe < MaxNumIteTe)) { | ||
| Pipe_Te_assumed = Pipe_Te_assumed - 0.1; | ||
| NumIteTe = NumIteTe + 1; | ||
| goto Label11; | ||
| } | ||
|
|
||
| if (std::abs(T_suction - SmallLoadTe) > TeTol) { | ||
| NumIteTe = 999; | ||
| T_suction = SmallLoadTe; | ||
| Pipe_SH_merged = 3.0; | ||
|
|
@@ -14131,12 +14153,21 @@ void VRFCondenserEquipment::VRFOU_CalcCompC(EnergyPlusData &state, | |
| goto Label13; | ||
| } | ||
|
|
||
| // when it gets here, either NumIteCcap = 30 or CapDiff > (Tolerance * Cap_Eva0) | ||
| if (CapDiff > (Tolerance * Cap_Eva0) && (Cap_Eva1 - Cap_Eva0) >= 0.0) { | ||
| NumIteCcap = 999; | ||
| CyclingRatio = Cap_Eva0 / Cap_Eva1; | ||
| } else { | ||
| CyclingRatio = 1.0; | ||
| } | ||
|
|
||
| Ncomp = this->RatedCompPower * CurveValue(state, this->OUCoolingPWRFT(CounterCompSpdTemp), T_discharge, T_suction); | ||
| OUCondHeatRelease = Ncomp + Cap_Eva1; | ||
|
There was a problem hiding this comment. Condenser heat rejection = power + evap capacity. How does this calculation relate to lines 11706 and 11707? Is OUCondHeatRelease the same as Q_h_OU at line 11707? And where is Q_c_OU *= cyclingRatio? I am getting confused as to which variables account for cycling and which don't. Does There was a problem hiding this comment. Ncomp should probably account for cycling So I basically followed this in the low-load approach. Originally I have the Ncomp and As the initial value of Ncomp (Ncomp = TU_CoolingLoad / this->CoolingCOP) does not have CyclingRatio in it, and the compressor is indeed going to cycling, then the cycling ratio will get multiplied multiple times, once each label10 loop. So I moved them to after the loop is completed. There was a problem hiding this comment. The plots you make of a transition from CyclingRatio = 1 to CyclingRatio < 1 (later in a day when the cooling load is decreasing) will show if these equations are correct. Maybe start there to determine how these equations need to be organized. There was a problem hiding this comment. The plot is in this comment #10353 (comment) There was a problem hiding this comment. It doesn't seem like the cycling ratio is double-counted. If we want to make sure, maybe we could double-check the output result against the hand calculation result at a certain fixed timestep. |
||
|
|
||
| this->CondensingTemp = T_discharge; // OU Tc' is updated due to OUCondHeatRelease updates, which is caused by IU Te' updates | ||
| // during low load conditions | ||
| this->EvaporatingTemp = T_suction; | ||
| this->IUEvaporatingTemp = T_suction; | ||
|
|
||
| break; // EXIT DoName1 | ||
|
|
||
|
|
@@ -14212,7 +14243,7 @@ void VRFCondenserEquipment::VRFOU_CalcCompH( | |
| Real64 RefTSat; // Saturated temperature of the refrigerant [C] | ||
| Real64 RefPLow; // Low Pressure Value for Ps (>0.0) [Pa] | ||
| Real64 RefPHigh; // High Pressure Value for Ps (max in tables) [Pa] | ||
| Real64 constexpr Tolerance(0.05); // Tolerance for condensing temperature calculation [C} | ||
| Array1D<Real64> CompEvaporatingPWRSpd; // Array for the compressor power at certain speed [W] | ||
| Array1D<Real64> CompEvaporatingCAPSpd; // Array for the evaporating capacity at certain speed [W] | ||
|
|
||
|
|
||
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.
Oops, something went wrong.
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
Ncomp is power. Ncomp should multiply by RTF.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
RTF was calculated later in the function. Should I follow this code and compute RTF here so that RTF is accessible here? Also I'm not sure why it is written like this instead of
VRFRTF = min(1.0, CyclingRatio)There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
I don't know why it's written like this either. This is in the heat recovery code so maybe it is assumed the compressor runs the entire time step. Don't use this code without modifying
PartLoadFraction = 1.0;. PLF needs to be calculated from the performance curve as a function of CyclingRatio asPartLoadFraction = max(0.7, CurveValue(state, vrf.CoolPLFFPLR, CyclingRatio));.RTF = PLR/PLF. For VRF CyclingRatio is PLR so RTF = CyclingRatio/PLF.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
In the component or physics-based VRF model, the OU doesn't have a curve for part load fraction. The available curves are the following
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
OK, so there is no cycling/start-up losses in this model. Using CyclingRatio is OK here.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
right.