Re: [EnergyPlus_Support] Hybrid Cooling Tower

Hi,

To summarize, on my condenser loop I've got two branches in parallel: one with a fluid cooler, one with a regular cooling tower. Each branch has a pump and the heat rejection equipment.

I'm trying to use EMS to alternate between the two branches based on a setpoint.

I've tried it two ways:

- As Chandan suggested, assigning a Pump Flow Rate Schedule to the pumps and modifying them with EMS at calling point "BeginTimestepBeforePredictor". The schedules are computer fine but only the fluid cooler runs all the time.

- Using an actuator to override the Pump Mass Flow Rate at calling point "InsideHVACSystemIterationLoop". I've added a binary variable that shows the EMS does run and goes through the IF statements just fine. But only the fluid cooler runs all the time (again).

I've got a good news and a bad news.

The good news is that I'm getting exactly the same results in both cases.
The bad one is that the results are not what I wanted or expected: only the fluid cooler runs, the cooling tower stays off.

Can someone with EMS experience tell me what I'm missing please?

I've attached both files if somebody would care to take a look.

Thanks,
Julien

--
Julien Marrec, EBCP, BPI MFBA
Energy&Sustainability Engineer
T: +33 6 95 14 42 13

LinkedIn (en) : www.linkedin.com/in/julienmarrec
LinkedIn (fr) : www.linkedin.com/in/julienmarrec/fr

2014-08-05 11:32 GMT+02:00 Julien Marrec <julien.marrec@xxxxxxxxx>:

Hi,

I've integrated Chandan's code.

I see that the schedule value is being computed correctly by the EMS program. Nevertheless, it seems that the pump mass flow rates as well as the pump electric power stays constant (if availability schedule is 0, the pump flow rate stays constant).

Can somebody explain why is that happening and how to remedy?

Thanks,
Julien

--
Julien Marrec, EBCP, BPI MFBA
Energy&Sustainability Engineer
T: +33 6 95 14 42 13

LinkedIn (en) : www.linkedin.com/in/julienmarrec
LinkedIn (fr) : www.linkedin.com/in/julienmarrec/fr

2014-08-04 11:30 GMT+02:00 Julien Marrec <julien.marrec@xxxxxxxxx>:

Chandan,

Thanks for this bit of code, I'll try it out as soon as possible, and might have some more questions as I have never used EMS yet.

Best,
Julien

--
Julien Marrec, EBCP, BPI MFBA
Energy&Sustainability Engineer
T: +33 6 95 14 42 13
www.julienmarrec.com

DoYouBuzz : www.doyoubuzz.com/julien-marrec_1
LinkedIn (fr) : www.linkedin.com/in/julienmarrec/fr

LinkedIn (en) : www.linkedin.com/in/julienmarrec

2014-08-02 10:58 GMT+02:00 Chandan Sharma chandangsharma@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx>:

Julien,

Availability managers in plant or air loop will turn on or off the entire loop (not individual dry or evaporative fluid coolers) so they may not serve the purpose in this case. If the dry and evaporative fluid coolers are in parallel branches with their branch pumps, these pumps' schedule can be modified using EMS. (Something like below). You can try and see if this works.

Another lot more time consuming but accurate way could be to use PlantComponent:UserDefined. This object will allow to define the behavior of hybrid cooling tower.

Branch,

Condenser Supply Fluidcooler Branch 1, !- Name

0, !- Maximum Flow Rate {m3/s}

, !- Pressure Drop Curve Name

Pump:VariableSpeed, !- Component 1 Object Type

Cond Circ Pump 1, !- Component 1 Name

Cond Circ Pump 1 Inlet Node, !- Component 1 Inlet Node Name

Condenser Fluidcooler Inlet Node, !- Component 1 Outlet Node Name

ACTIVE, !- Component 1 Branch Control Type

Fluidcooler:SingleSpeed, !- Component 2 Object Type

Big FluidCooler, !- Component 2 Name

Condenser Fluidcooler Inlet Node, !- Component 2 Inlet Node Name

Condenser Fluidcooler Outlet Node, !- Component 2 Outlet Node Name

ACTIVE; !- Component 2 Branch Control Type

Branch,

Condenser Supply Fluidcooler Branch 2, !- Name

0, !- Maximum Flow Rate {m3/s}

, !- Pressure Drop Curve Name

Pump:VariableSpeed, !- Component 1 Object Type

Cond Circ Pump 2, !- Component 1 Name

Cond Circ Pump 2 Inlet Node, !- Component 1 Inlet Node Name

Condenser EvapFluidcooler Inlet Node, !- Component 1 Outlet Node Name

ACTIVE, !- Component 1 Branch Control Type

EvaporativeFluidCooler:SingleSpeed, !- Component 2 Object Type

Big EvaporativeFluidCooler, !- Component 2 Name

Condenser EvapFluidcooler Inlet Node, !- Component 2 Inlet Node Name

Condenser EvapFluidcooler Outlet Node, !- Component 2 Outlet Node Name

ACTIVE; !- Component 2 Branch Control Type

Pump:VariableSpeed,

Cond Circ Pump 1, !- Name

Cond Circ Pump 1 Inlet Node, !- Inlet Node Name

Condenser Fluidcooler Inlet Node, !- Outlet Node Name

0.001388, !- Rated Flow Rate {m3/s}

297500, !- Rated Pump Head {Pa}

500, !- Rated Power Consumption {W}

.87, !- Motor Efficiency

0.0, !- Fraction of Motor Inefficiencies to Fluid Stream

0, !- Coefficient 1 of the Part Load Performance Curve

1, !- Coefficient 2 of the Part Load Performance Curve

0, !- Coefficient 3 of the Part Load Performance Curve

0, !- Coefficient 4 of the Part Load Performance Curve

0, !- Minimum Flow Rate {m3/s}

INTERMITTENT, !- Pump Control Type

CondCircPump1PumpAvailSched; !- Pump Flow Rate Schedule Name

Fluidcooler:SingleSpeed,

Big FluidCooler, !- Name

Condenser Fluidcooler Inlet Node, !- Water Inlet Node Name

Condenser Fluidcooler Outlet Node, !- Water Outlet Node Name

NominalCapacity, !- Performance Input Method

, !- Design Air Flow Rate U-factor Times Area Value {W/K}

58601., !- Nominal Capacity {W}

51.67, !- Design Entering Water Temperature {C}

35, !- Design Entering Air Temperature {C}

25.6, !- Design Entering Air Wetbulb Temperature {C}

0.001388, !- Design Water Flow Rate {m3/s}

9.911, !- Design Air Flow Rate {m3/s}

autosize; !- Design Air Flow Rate Fan Power {W}

Pump:VariableSpeed,

Cond Circ Pump 2, !- Name

Cond Circ Pump 2 Inlet Node, !- Inlet Node Name

Condenser EvapFluidcooler Inlet Node, !- Outlet Node Name

0.001388, !- Rated Flow Rate {m3/s}

297500, !- Rated Pump Head {Pa}

500, !- Rated Power Consumption {W}

.87, !- Motor Efficiency

0.0, !- Fraction of Motor Inefficiencies to Fluid Stream

0, !- Coefficient 1 of the Part Load Performance Curve

1, !- Coefficient 2 of the Part Load Performance Curve

0, !- Coefficient 3 of the Part Load Performance Curve

0, !- Coefficient 4 of the Part Load Performance Curve

0, !- Minimum Flow Rate {m3/s}

INTERMITTENT, !- Pump Control Type

CondCircPump2PumpAvailSched; !- Pump Flow Rate Schedule Name

EvaporativeFluidcooler:SingleSpeed,

Big EvaporativeFluidCooler, !- Name

Condenser EvapFluidcooler Inlet Node, !- Water Inlet Node Name

Condenser EvapFluidcooler Outlet Node, !- Water Outlet Node Name

3.02, !- Design Air Flow Rate {m3/s}

2250, !- Design Air Flow Rate Fan Power {W}

0.002208, !- Design Spray Water Flow Rate {m3/s}

UserSpecifiedDesignCapacity, !- Performance Input Method

, !- Outdoor Air Inlet Node Name

, !- Heat Rejection Capacity and Nominal Capacity Sizing Ratio

, !- Standard Design Capacity {W}

, !- Design Air Flow Rate U-factor Times Area Value {W/K}

0.001703, !- Design Water Flow Rate {m3/s}

87921, !- User Specified Design Capacity {W}

46.11, !- Design Entering Water Temperature {C}

35, !- Design Entering Air Temperature {C}

25.6; !- Design Entering Air Wet-bulb Temperature {C}

Schedule:Compact,

CondCircPump1PumpAvailSched, !- Name

Fraction, !- Schedule Type Limits Name

Through: 12/31, !- Field 1

For: AllDays, !- Field 2

Until: 24:00,0.0; !- Field 3

Schedule:Compact,

CondCircPump2PumpAvailSched, !- Name

Fraction, !- Schedule Type Limits Name

Through: 12/31, !- Field 1

For: AllDays, !- Field 2

Until: 24:00,0.0; !- Field 3

EnergyManagementSystem:Actuator,

Set_CondCircPump1Avail_Sched, !- Name

CondCircPump1PumpAvailSched, !- Actuated Component Unique Name

Schedule:Compact, !- Actuated Component Type

Schedule Value; !- Actuated Component Control Type

EnergyManagementSystem:Actuator,

Set_CondCircPump2Avail_Sched, !- Name

CondCircPump2PumpAvailSched, !- Actuated Component Unique Name

Schedule:Compact, !- Actuated Component Type

Schedule Value; !- Actuated Component Control Type

EnergyManagementSystem:ProgramCallingManager,

My Setpoint Schedule Calculator Example,

BeginTimestepBeforePredictor,

Set_CondCircPumpAvail_Sched_Prog;

EnergyManagementSystem:Sensor,

OutdoorTemp, !- Name

Environment, !- Output:Variable Index Key Name

Site Outdoor Air Drybulb Temperature; !- Output:Variable Name

EnergyManagementSystem:Program,

Set_CondCircPumpAvail_Sched_Prog,

IF (OutdoorTemp <= 18.33 && OutdoorTemp > 0.0),

Set Set_CondCircPump1Avail_Sched = 1.0 ,

Set Set_CondCircPump2Avail_Sched = 0.0 ,

ELSEIF (OutdoorTemp > 21.0),

Set Set_CondCircPump1Avail_Sched = 0.0 ,

Set Set_CondCircPump2Avail_Sched = 1.0 ,

ENDIF;

Output:Variable,CondCircPump1PumpAvailSched,Schedule Value,timestep;

Output:Variable,CondCircPump2PumpAvailSched,Schedule Value,timestep;

Output:Variable,Cond Circ Pump 1,Pump Electric Power,timestep;

Output:Variable,Cond Circ Pump 1,Pump Mass Flow Rate,timestep;

Output:Variable,Cond Circ Pump 2,Pump Electric Power,timestep;

Output:Variable,Cond Circ Pump 2,Pump Mass Flow Rate,timestep;

On Fri, Aug 1, 2014 at 10:17 PM, Julien Marrec julien.marrec@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

Hi,

Has anyone successfully modeled an hybrid cooling tower in E+?

By hybrid I mean running dry until a switchover temperature. When the outdoor dry bulb is above, say, 65°F, you start spraying.

How would you do it?

Should I use for example one CoolingTower:TwoSpeed and one FluidCooler:TwoSpeed and turn them on/off based on outdoor temperature using an availabilitymanager?

Thanks for any insight you can provide.

Best,
Julien

--
Julien Marrec, EBCP, BPI MFBA
Energy&Sustainability Engineer
T: +33 6 95 14 42 13
www.julienmarrec.com

DoYouBuzz : www.doyoubuzz.com/julien-marrec_1
LinkedIn (fr) : www.linkedin.com/in/julienmarrec/fr

LinkedIn (en) : www.linkedin.com/in/julienmarrec