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[EnergyPlus_Support] Re: Fwd: Central Heat Production vs terminal units
Temperatures below 5ºC have npo reason to cause that kind of
behaviour, have they?
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "anarui.oliveira"
<anarui.oliveira@...> wrote:
>
> Thanks.
> I based my adpated model on that Example File, and I've checked
again
> now... I think that node connections and the like are correct...
> I get some warnings about freezing possibility, but other than
that,
> it seems OK... except that the Heat Pump DX Coil gives a lot more
> energy than is being used by the demand side coils.
> I'll keep trying to find out the bug, I guess...
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad
> <RRaustad@> wrote:
> >
> > Look at the example file HeatPumpWaterHeater.idf. In your file,
> hook up
> > the plant loop to the USE SIDE nodes in the WaterHeater:Mixed
> object.
> > Just use a 1 for the use side effectiveness value.
> >
> > HEAT PUMP:WATER HEATER,
> > Zone5HeatPumpWaterHeater,!- Heat Pump Name
> > HeatPumpWaterHeaterSch, !- Availability Schedule Name
> > HPWHTempSch, !- Heat Pump Compressor Set Point
> > Temperature Schedule Name
> > 2.0, !- Dead Band Temperature Difference
> {deltaC}
> > HPWHWaterInletNode, !- Condenser Water Inlet Node Name
> > HPWHWaterOutletNode, !- Condenser Water Outlet Node Name
> > autocalculate, !- Condenser Water Volumetric Flow
> Rate {m3/s}
> > autocalculate, !- Evaporator Air Volumetric Flow
Rate
> {m3/s}
> > Zone and Outdoor Air, !- Inlet Air Configuration
> > HPWHAirOutletNode, !- Heat Pump Air Inlet Node Name
> > HPWHAirInletNode, !- Heat Pump Air Outlet Node Name
> > HPWHOutdoorAirInletNode, !- Outside Air Node Name
> > HPWHExhaustAirOutletNode,!- Exhaust Air Node Name
> > , !- Inlet Air Temperature Schedule
Name
> > , !- Inlet Air Humidity Schedule Name
> > SPACE5-1, !- Inlet Air Zone Name
> > Water Heater:Mixed, !- Water Heater Tank Type
> > HPWHTank, !- Water Heater Tank Name
> > , !- Water Heater Tank Use Side Inlet
> Node Name
> > , !- Water Heater Tank Use Side Outlet
> Node Name
> > Coil:DX:HeatPumpWaterHeater, !- DX Coil Type
> > HPWHDXCoil, !- DX Coil Name
> > 5.0, !- Minimum Inlet Air Temperature for
> Heat
> > Pump Compressor Operation {C}
> > Zone, !- Compressor Location
> > , !- Compressor Ambient Temperature
> Schedule Name
> > Fan:Simple:OnOff, !- Fan Type
> > HPWHFan, !- Fan Name
> > Draw Through, !- Fan Placement
> > 15.0, !- On-Cycle Parasitic Electric Load
{W}
> > 5.0, !- Off-Cycle Parasitic Electric Load
> {W}
> > Zone, !- Parasitic Heat Rejection Location
> > HPWHInletAirMixerNode, !- Inlet Air Mixer Node Name
> > HPWHOutletAirSplitterNode, !- Outlet Air Splitter Node Name
> > HPWHMixerInletAirSch; !- Inlet Air Mixer Schedule Name
> >
> >
> > WATER HEATER:MIXED,
> > HPWHTank, !- Name
> > 0.3785, !- Tank Volume {m3}
> > Hot Water Setpoint Temp Schedule, !- Setpoint Temperature
> Schedule
> > 2.0, !- Deadband Temperature Difference
> {deltaC}
> > 82.2222, !- Maximum Temperature Limit {C}
> > CYCLE, !- Heater Control Type
> > 5000, !- Heater Maximum Capacity {W}
> > 0, !- Heater Minimum Capacity {W}
> > , !- Heater Ignition Minimum Flow Rate
> {m3/s}
> > , !- Heater Ignition Delay {s}
> > ELECTRICITY, !- Heater Fuel Type
> > 0.95, !- Heater Thermal Efficiency
> > , !- Part Load Factor Curve
> > 10, !- Off-Cycle Parasitic Fuel
> Consumption
> > Rate {W}
> > ELECTRICITY, !- Off-Cycle Parasitic Fuel Type
> > 0, !- Off-Cycle Parasitic Heat Fraction
> To Tank
> > 30, !- On-Cycle Parasitic Fuel
Consumption
> Rate {W}
> > ELECTRICITY, !- On-Cycle Parasitic Fuel Type
> > 0, !- On-Cycle Parasitic Heat Fraction
To
> Tank
> > ZONE, !- Ambient Temperature Indicator
> > , !- Ambient Temperature Schedule
> > SPACE5-1, !- Ambient Temperature Zone
> > , !- Ambient Temperature Outside Air
Node
> > 2.0, !- Off-Cycle Loss Coefficient To
> Ambient
> > Temperature {W/K}
> > 1.0, !- Off-Cycle Loss Fraction To Zone
> > 2.0, !- On-Cycle Loss Coefficient To
> Ambient
> > Temperature {W/K}
> > 1.0, !- On-Cycle Loss Fraction To Zone
> > 0.00379, !- Peak Volumetric Use Flow Rate
{m3/s}
> > Hot Water Demand Schedule, !- Use Flow Rate Fraction Schedule
> > , !- Cold Water Supply Temperature
> Schedule
> > , !- Use Side Inlet Node
> > , !- Use Side Outlet Node
> > , !- Use Side Effectiveness
> > HPWHWaterOutletNode, !- Source Side Inlet Node
> > HPWHWaterInletNode, !- Source Side Outlet Node
> > 0.95; !- Source Side Effectiveness
> >
> >
> > COIL:DX:HEATPUMPWATERHEATER,
> > HPWHDXCoil, !- Coil Name
> > 4000.0, !- Heating Capacity {W}
> > 3.2, !- Rated COP {W/W}
> > 0.6956, !- Rated SHR (gross)
> > 29.44, !- Rated Evaporator Inlet Air Dry-
Bulb
> > Temperature {C}
> > 22.22, !- Rated Evaporator Inlet Air Wet-
Bulb
> > Temperature {C}
> > 55.72, !- Rated Condenser Inlet Water
> Temperature {C}
> > autocalculate, !- Rated Evaporator Air Volumetric
> Flow
> > Rate {m3/s}
> > autocalculate, !- Rated Condenser Water Volumetric
> Flow
> > Rate {m3/s}
> > No, !- Evaporator Fan Power Included in
> Rated COP
> > No, !- Condenser Pump Power Included in
> Rated COP
> > No, !- Condenser Pump Heat Included in
> Rated
> > Heating Capacity and Rated COP
> > 150.0, !- Condenser Water Pump Power {W}
> > 0.1, !- Fraction of Condenser Pump Heat
to
> Water
> > HPWHInletAirMixerNode, !- Evaporator Air Inlet Node Name
> > HPWHDXCoilAirOutletNode, !- Evaporator Air Outlet Node Name
> > HPWHWaterInletNode, !- Condenser Water Inlet Node Name
> > HPWHWaterOutletNode, !- Condenser Water Outlet Node Name
> > 100.0, !- Crankcase Heater Capacity {W}
> > 5.0, !- Maximum Ambient Temperature for
> > Crankcase Heater Operation {C}
> > wet-bulb temperature, !- Evaporator Air Temperature Type
for
> > Curve Objects
> > HPWHHeatingCapFTemp, !- Heating Capacity Modifier Curve
> Name
> > (function of temperature)
> > , !- Heating Capacity Modifier Curve
> Name
> > (function of air flow fraction)
> > , !- Heating Capacity Modifier Curve
> Name
> > (function of water flow fraction)
> > HPWHHeatingCOPFTemp, !- Heating COP Modifier Curve Name
> > (function of temperature)
> > , !- Heating COP Modifier Curve Name
> > (function of air flow fraction)
> > , !- Heating COP Modifier Curve Name
> > (function of water flow fraction)
> > HPWHPLFFPLR; !- Part Load Fraction Correlation
Name
> > (function of part load ratio)
> >
> > anarui.oliveira wrote:
> > >
> > > Maybe this additional information helps:
> > >
> > > ...I started out with a model of a boiler created with Compact
> HVAC,
> > > and then expanded it and substituted the boiler by the Heat
Pump
> Water
> > > Heater.
> > > The expanded model with the boiler works fine... so I guess I
> missed
> > > something when adapting it to a model with a heat pump?...
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>, "anarui.oliveira"
> > > <anarui.oliveira@> wrote:
> > >
> > > Hi everyone.
> > >
> > > I modelled a system with a central Heat pump (air-to-water),
> producing
> > > heat for a hot water loop serving 3 Air Treatment Units and some
> > > terminal unit ventilators, but the thermal heating rate/energy
> produced
> > > by the central heat pump is much (2-3 times) higher than the
sum
> of the
> > > heating rates/energy of all the coils in the ATUs and terminal
> units...
> > > It seems as if the control os this central unit is not
performing
> > > properly, but I can't figure out why...
> > >
> > > Could anyone help?
> > >
> > > Thanks in advance,
> > > Ana Rui.
> > >
> > > --- End forwarded message ---
> > >
> > >
> >
> > --
> > Richard A. Raustad
> > Senior Research Engineer
> > Florida Solar Energy Center
> > University of Central Florida
> > 1679 Clearlake Road
> > Cocoa, FL 32922-5703
> > Phone: (321) 638-1454
> > Fax: (321) 638-1439 or 1010
> > Visit our web site at: http://www.fsec.ucf.edu
> >
> > UCF - From Promise to Prominence: Celebrating 40 Years
> >
>
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