Template:Embedded Heat Exchanger (HX) Data Section

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Tag (Long/Short) Input / Calc Description/Calculated Variables / Options
Heater / Cooler Requirements
On Tick Box Switches the Embedded Heat Exchanger on/off
NumofHeater Input Visible when Embedded Heater / cooler is used. Specifies the number of embedded heat exchangers in the evaporator.
Type Fixed Heat Flow This will exchange a fixed amount of heat between two streams. No phase change will take place automatically.
Sensible This will allow sensible heat exchange between two streams. No phase change will take place.
Condensing Only visible when Embedded Heater is used. This is used to condense the steam. Steam must be connected to Embedded HX Shell (inlet).
Evaporating Only visible when Embedded Cooler is used. This is used to evaporate the water. Water (or another component with Predefined Flashing Data) must be connected to Embedded HX Shell (inlet).
CondensingMethod
(Only visible when Embedded Heater is used)
All The Steam addition is manually specified by the user. All steam will condense.
All (Calc Demand) The steam demand is calculated base on the user specified Heater HTC and Area (UA). User needs to set the steam flow based on the calculated amount.
All-Demand General The steam supply comes from (directly or indirectly) a Feeder with Demand.on selected.
All-Demand Flashtrain The steam supply comes from another process unit in Flash train mode (usually the vapour from the preceding evaporation stage)
EvaporatingMethod
(Only visible when Embedded Cooler is used)
All The component defined in the VLE Tab will fully evaporate.
All (Calc Demand) The demand is calculated base on the user specified Heater HTC and Area (UA). User needs to set the flow based on the calculated amount.
All-Demand General The flow supply comes from (directly or indirectly) a Feeder with Demand.on selected.
DutyReqd Input The required fixed heat flow to be exchanged between the two streams. Only visible when Fixed Heat Flow method is used.
HTC Input/Calc Visible with method set to any of the demand methods, allows the user to specify the heat transfer coefficient.
Area Input/Calc Visible with method set to any of the demand methods, allows the user to specify the heat transfer area per heater.
Heater / Cooler Results
Duty Calc The calculated Heat Exchanger Duty
TotalArea Calc The total Area used (HX Area * number of HX).
U*A / UA Calc The heat exchanger UA.
LMTD Calc The calculated log mean temperature difference.
TheoreticalDuty / TheorDuty Calc The theoretical duty of the heat exchanger.
HeatFlow Calc The total heat exchanged.
Calculated Vapour/Liquid Flow Demand
DemandFlow.Reqd Calc The calculated demand flow to meet the Heat Exchanger requirements. When the HX is not in Demand General or Demand FlashTrain mode, use a General controller or SetTag Controller to get this value to set the Embedded HX Shell (in) flowrate.
DemandFlow.Actual Calc The actual demand flow to Heater Exchanger .
DemandFlow.Error Calc The mass imbalance in the unit operation. This will warn the user if the amount of flow supplied exceeds the heat exchanger requirements. Most common when the heater is not in Demand General or Demand FlashTrain mode and the steam flow has not been set up to auto adjust.
Tube Side (Recycle Stream)
Tube.TemperatureIn / Tube.Ti Calc Tube in temperature.
Tube.TemperatureOut / Tube.To Calc Tube out temperature.
Tube.PressureIn / Tube.Pi Calc Tube in pressure.
Tube.MassFlow / Tube.Qm Calc The mass flowrate going through the tube side..
Shell Side (Condensing / Evaporating)
Shell.TemperatureIn / Shell.Ti Calc Shell in temperature.
Shell.TemperatureOut / Shell.To Calc Shell out temperature.
Shell.PressureIn / Shell.Pi Calc Shell in pressure.
Shell.MassFlow / Shell.Qm Calc The mass flowrate going through the Shell side.
Shell.DmdQm Calc Only visible if part of a flash train. This is the amount of steam needed from connected flash train units (flash tank or steam feeders), not including any fixed amount of steam input.
Shell.FxdQm Calc Only visible if part of a flash train. This is the amount of steam added in manually, thus not from connected flash train units. Note this portion of steam addition is not included in the pressure calculation of the flash train group.
Flash Train Macro Model

Note: Extra fields are visible if the unit is part of a Flash Train. These fields are described below. Please refer to Flash Train.

VapourMassFlowReqd / VQmReqd Calc The calculated mass flow of steam required by the Embedded Heater Condenser.
CondMassFlow / CondQm Calc The amount of steam condensed by the Embedded Heater Condenser.
MinSatPress Calc The minimum saturated pressure of steam that could satisfy the heating requirements of the Embedded Heater Condenser.
FlashTrain Display A unique tag assigned to the flash train by SysCAD. Each unit in the flash train will have the same tag in this block.
FlashTearBlock Display Displays the name of the tear block that is part of the Flash Train.
FlashTrainEqp List This contains a list of all of the equipment tags in this flash train. the list might be as follows:
FT_EVAPORATOR_2_HX
FT_EVAPORATOR_3_Evap
PAdvBase Input Additional damping or acceleration for calculated pressure change (DP) for the iteration. DP = DP * PAdvBase when PAdvExtra=0.
PAdvExtra Input Additional damping or acceleration for calculated pressure change (DP) for the iteration. DP = DP * (PAdvBase + PAdvExtra*(VQmReqd-VQm)/Max(VQmReqd,VQm)).