Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
If you review the EnergyPlus example file named RefrigeratedWarehouse.idf, it should contain all of the object types that you will need. Below is an example of one air chiller and the thermostat settings for the refrigeration zone servd by that chiller in that example file.
!- =========== ALL OBJECTS IN CLASS: Refrigeration:AirChiller ===========
! Subfreezer
! -25C is desired zone temperature
! max sensible load was 136,000W with ideal air (no latent included)
! avg cap was 77,000W with ideal air (no latent included)
! Try with 300,000W total and DT1 of 8C, so unit load factor is 40,000 W/DeltaC
! See BAC AS5S-4084-050L, fan 0.5 HP (0.5 hp = 373 W), airflow 26,250 cfm(1 ft3 = 0.02833 m3, so ~12.4 m3/s),
! frosted capacity 20,650 B/h-F (~10,900 W/C), so need 3 of them
! Will do Evap T of -33C, let heater = 200W,
! Use electric defrost - capacity large to limit time and handle latent load
! Electric defrost capacity, BAC recommends 11 W/ft2 (this model has 5,006 ft2), so 55066W
Refrigeration:AirChiller,
SubFreezerAirChiller_1, !- Name
AvailAllYear, !- Availability Schedule Name
UnitLoadFactorSensibleOnly, !- Capacity Rating Type
10900., !- Rated Unit Load Factor {W/K}
, !- Rated Capacity {W}
, !- Rated Relative Humidity {percent}
-33., !- Rated Cooling Source Temperature {C}
8., !- Rated Temperature Difference DT1 {deltaC}
11., !- Maximum Temperature Difference Between Inlet Air and Evaporating Temperature {deltaC}
, !- Coil Material Correction Factor {dimensionless}
, !- Refrigerant Correction Factor {dimensionless}
LinearSHR60, !- Capacity Correction Curve Type
, !- Capacity Correction Curve Name
1.5, !- SHR60 Correction Factor {dimensionless}
200., !- Rated Total Heating Power {W}
AirChillerDripDownSched1,!- Heating Power Schedule Name
, !- Fan Speed Control Type
375., !- Rated Fan Power {W}
12.4, !- Rated Air Flow {m3/s}
, !- Minimum Fan Air Flow Ratio {dimensionless}
Electric, !- Defrost Type
TimeSchedule, !- Defrost Control Type
AirChillerDefrostSched1, !- Defrost Schedule Name
AirChillerDripDownSched1,!- Defrost Drip-Down Schedule Name
55066., !- Defrost Power {W}
, !- Temperature Termination Defrost Fraction to Ice {dimensionless}
, !- Vertical Location
; !- Average Refrigerant Charge Inventory {kg}
The air chiller will then be part of the case and walkin list, as well as the zone HVAC refrigeration chiller set.
Refrigeration:CaseAndWalkInList,
SubFreezerAirChillerList,!- Name
SubFreezerAirChiller_1, !- Case or WalkIn 1 Name
SubFreezerAirChiller_2, !- Case or WalkIn 2 Name
SubFreezerAirChiller_3; !- Case or WalkIn 3 Name
ZoneHVAC:RefrigerationChillerSet,
SubFreezerChillerSet, !- Name
, !- Availability Schedule Name
SubFreezer, !- Zone Name
, !- Air Inlet Node Name
, !- Air Outlet Node Name
SubFreezerAirChiller_1, !- Air Chiller 1 Name
SubFreezerAirChiller_2, !- Air Chiller 2 Name
SubFreezerAirChiller_3; !- Air Chiller 3 Name
The zone HVAC refrigeration chiller set is then assigned to the zone HVAC equipment list.
ZoneHVAC:EquipmentList,
SubFreezerEquipment, !- Name
SequentialLoad, !- Load Distribution Scheme
ZoneHVAC:RefrigerationChillerSet, !- Zone Equipment 1 Object Type
SubFreezerChillerSet, !- Zone Equipment 1 Name
1, !- Zone Equipment 1 Cooling Sequence
1, !- Zone Equipment 1 Heating or No-Load Sequence
, !- Zone Equipment 1 Sequential Cooling Fraction Schedule Name
; !- Zone Equipment 1 Sequential Heating Fraction Schedule Name
This equipment list is referenced by the zone HVAC equipment connections, which also defines the zone that is connected to that equipment list.
ZoneHVAC:EquipmentConnections,
SubFreezer, !- Zone Name
SubFreezerEquipment, !- Zone Conditioning Equipment List Name
, !- Zone Air Inlet Node or NodeList Name
, !- Zone Air Exhaust Node or NodeList Name
NODE_144, !- Zone Air Node Name
NODE_145; !- Zone Return Air Node or NodeList Name
This zone will then have zone control thermostat objects define the thermostat settings (cooling below -25C).
ZoneControl:Thermostat,
SubFreezer Thermostat, !- Name
SubFreezer, !- Zone or ZoneList Name
Zone Control Type Sched Dual YearRound, !- Control Type Schedule Name
ThermostatSetpoint:DualSetpoint, !- Control 1 Object Type
Dual Setpoint Blast Freeze; !- Control 1 Name
ThermostatSetpoint:DualSetpoint,
Dual Setpoint Blast Freeze, !- Name
Heating Setpoints_BlastFreeze, !- Heating Setpoint Temperature Schedule Name
Cooling Setpoints_BlastFreeze; !- Cooling Setpoint Temperature Schedule Name
Schedule:Compact,
Cooling Setpoints_BlastFreeze, !- Name
Temperature, !- Schedule Type Limits Name
Through: 12/31, !- Field 1
For: AllDays, !- Field 2
Until: 7:00,-25., !- Field 3
Until: 20:00,-25., !- Field 5
Until: 24:00,-25.; !- Field 7
For your case, you want to make two changes to this example:
| | 2 | No.2 Revision |
If you review the EnergyPlus example file named RefrigeratedWarehouse.idf, it should contain all of the object types that you will need. Below is an example of one air chiller and the thermostat settings for the refrigeration zone servd served by that chiller in that example file.
!- =========== ALL OBJECTS IN CLASS: Refrigeration:AirChiller ===========
! Subfreezer
! -25C is desired zone temperature
! max sensible load was 136,000W with ideal air (no latent included)
! avg cap was 77,000W with ideal air (no latent included)
! Try with 300,000W total and DT1 of 8C, so unit load factor is 40,000 W/DeltaC
! See BAC AS5S-4084-050L, fan 0.5 HP (0.5 hp = 373 W), airflow 26,250 cfm(1 ft3 = 0.02833 m3, so ~12.4 m3/s),
! frosted capacity 20,650 B/h-F (~10,900 W/C), so need 3 of them
! Will do Evap T of -33C, let heater = 200W,
! Use electric defrost - capacity large to limit time and handle latent load
! Electric defrost capacity, BAC recommends 11 W/ft2 (this model has 5,006 ft2), so 55066W
Refrigeration:AirChiller,
SubFreezerAirChiller_1, !- Name
AvailAllYear, !- Availability Schedule Name
UnitLoadFactorSensibleOnly, !- Capacity Rating Type
10900., !- Rated Unit Load Factor {W/K}
, !- Rated Capacity {W}
, !- Rated Relative Humidity {percent}
-33., !- Rated Cooling Source Temperature {C}
8., !- Rated Temperature Difference DT1 {deltaC}
11., !- Maximum Temperature Difference Between Inlet Air and Evaporating Temperature {deltaC}
, !- Coil Material Correction Factor {dimensionless}
, !- Refrigerant Correction Factor {dimensionless}
LinearSHR60, !- Capacity Correction Curve Type
, !- Capacity Correction Curve Name
1.5, !- SHR60 Correction Factor {dimensionless}
200., !- Rated Total Heating Power {W}
AirChillerDripDownSched1,!- Heating Power Schedule Name
, !- Fan Speed Control Type
375., !- Rated Fan Power {W}
12.4, !- Rated Air Flow {m3/s}
, !- Minimum Fan Air Flow Ratio {dimensionless}
Electric, !- Defrost Type
TimeSchedule, !- Defrost Control Type
AirChillerDefrostSched1, !- Defrost Schedule Name
AirChillerDripDownSched1,!- Defrost Drip-Down Schedule Name
55066., !- Defrost Power {W}
, !- Temperature Termination Defrost Fraction to Ice {dimensionless}
, !- Vertical Location
; !- Average Refrigerant Charge Inventory {kg}
The air chiller will then be part of the case and walkin list, as well as the zone HVAC refrigeration chiller set.
Refrigeration:CaseAndWalkInList,
SubFreezerAirChillerList,!- Name
SubFreezerAirChiller_1, !- Case or WalkIn 1 Name
SubFreezerAirChiller_2, !- Case or WalkIn 2 Name
SubFreezerAirChiller_3; !- Case or WalkIn 3 Name
ZoneHVAC:RefrigerationChillerSet,
SubFreezerChillerSet, !- Name
, !- Availability Schedule Name
SubFreezer, !- Zone Name
, !- Air Inlet Node Name
, !- Air Outlet Node Name
SubFreezerAirChiller_1, !- Air Chiller 1 Name
SubFreezerAirChiller_2, !- Air Chiller 2 Name
SubFreezerAirChiller_3; !- Air Chiller 3 Name
The zone HVAC refrigeration chiller set is then assigned to the zone HVAC equipment list.
ZoneHVAC:EquipmentList,
SubFreezerEquipment, !- Name
SequentialLoad, !- Load Distribution Scheme
ZoneHVAC:RefrigerationChillerSet, !- Zone Equipment 1 Object Type
SubFreezerChillerSet, !- Zone Equipment 1 Name
1, !- Zone Equipment 1 Cooling Sequence
1, !- Zone Equipment 1 Heating or No-Load Sequence
, !- Zone Equipment 1 Sequential Cooling Fraction Schedule Name
; !- Zone Equipment 1 Sequential Heating Fraction Schedule Name
This equipment list is referenced by the zone HVAC equipment connections, which also defines the zone that is connected to that equipment list.
ZoneHVAC:EquipmentConnections,
SubFreezer, !- Zone Name
SubFreezerEquipment, !- Zone Conditioning Equipment List Name
, !- Zone Air Inlet Node or NodeList Name
, !- Zone Air Exhaust Node or NodeList Name
NODE_144, !- Zone Air Node Name
NODE_145; !- Zone Return Air Node or NodeList Name
This zone will then have zone control thermostat objects define the thermostat settings (cooling below -25C).
ZoneControl:Thermostat,
SubFreezer Thermostat, !- Name
SubFreezer, !- Zone or ZoneList Name
Zone Control Type Sched Dual YearRound, !- Control Type Schedule Name
ThermostatSetpoint:DualSetpoint, !- Control 1 Object Type
Dual Setpoint Blast Freeze; !- Control 1 Name
ThermostatSetpoint:DualSetpoint,
Dual Setpoint Blast Freeze, !- Name
Heating Setpoints_BlastFreeze, !- Heating Setpoint Temperature Schedule Name
Cooling Setpoints_BlastFreeze; !- Cooling Setpoint Temperature Schedule Name
Schedule:Compact,
Cooling Setpoints_BlastFreeze, !- Name
Temperature, !- Schedule Type Limits Name
Through: 12/31, !- Field 1
For: AllDays, !- Field 2
Until: 7:00,-25., !- Field 3
Until: 20:00,-25., !- Field 5
Until: 24:00,-25.; !- Field 7
For your case, you want to make two changes to this example:
| | 3 | No.3 Revision |
If you review the EnergyPlus example file named RefrigeratedWarehouse.idf, it should contain all of the object types that you will need. Below is an example of one air chiller and the thermostat settings for the refrigeration zone served by that chiller in that example file.
!- =========== ALL OBJECTS IN CLASS: Refrigeration:AirChiller ===========
! Subfreezer
! -25C is desired zone temperature
! max sensible load was 136,000W with ideal air (no latent included)
! avg cap was 77,000W with ideal air (no latent included)
! Try with 300,000W total and DT1 of 8C, so unit load factor is 40,000 W/DeltaC
! See BAC AS5S-4084-050L, fan 0.5 HP (0.5 hp = 373 W), airflow 26,250 cfm(1 ft3 = 0.02833 m3, so ~12.4 m3/s),
! frosted capacity 20,650 B/h-F (~10,900 W/C), so need 3 of them
! Will do Evap T of -33C, let heater = 200W,
! Use electric defrost - capacity large to limit time and handle latent load
! Electric defrost capacity, BAC recommends 11 W/ft2 (this model has 5,006 ft2), so 55066W
Refrigeration:AirChiller,
SubFreezerAirChiller_1, !- Name
AvailAllYear, !- Availability Schedule Name
UnitLoadFactorSensibleOnly, !- Capacity Rating Type
10900., !- Rated Unit Load Factor {W/K}
, !- Rated Capacity {W}
, !- Rated Relative Humidity {percent}
-33., !- Rated Cooling Source Temperature {C}
8., !- Rated Temperature Difference DT1 {deltaC}
11., !- Maximum Temperature Difference Between Inlet Air and Evaporating Temperature {deltaC}
, !- Coil Material Correction Factor {dimensionless}
, !- Refrigerant Correction Factor {dimensionless}
LinearSHR60, !- Capacity Correction Curve Type
, !- Capacity Correction Curve Name
1.5, !- SHR60 Correction Factor {dimensionless}
200., !- Rated Total Heating Power {W}
AirChillerDripDownSched1,!- Heating Power Schedule Name
, !- Fan Speed Control Type
375., !- Rated Fan Power {W}
12.4, !- Rated Air Flow {m3/s}
, !- Minimum Fan Air Flow Ratio {dimensionless}
Electric, !- Defrost Type
TimeSchedule, !- Defrost Control Type
AirChillerDefrostSched1, !- Defrost Schedule Name
AirChillerDripDownSched1,!- Defrost Drip-Down Schedule Name
55066., !- Defrost Power {W}
, !- Temperature Termination Defrost Fraction to Ice {dimensionless}
, !- Vertical Location
; !- Average Refrigerant Charge Inventory {kg}
The air chiller will then be part of the case and walkin list, as well as the zone HVAC refrigeration chiller set.
Refrigeration:CaseAndWalkInList,
SubFreezerAirChillerList,!- Name
SubFreezerAirChiller_1, !- Case or WalkIn 1 Name
SubFreezerAirChiller_2, !- Case or WalkIn 2 Name
SubFreezerAirChiller_3; !- Case or WalkIn 3 Name
ZoneHVAC:RefrigerationChillerSet,
SubFreezerChillerSet, !- Name
, !- Availability Schedule Name
SubFreezer, !- Zone Name
, !- Air Inlet Node Name
, !- Air Outlet Node Name
SubFreezerAirChiller_1, !- Air Chiller 1 Name
SubFreezerAirChiller_2, !- Air Chiller 2 Name
SubFreezerAirChiller_3; !- Air Chiller 3 Name
The zone HVAC refrigeration chiller set is then assigned to the zone HVAC equipment list.
ZoneHVAC:EquipmentList,
SubFreezerEquipment, !- Name
SequentialLoad, !- Load Distribution Scheme
ZoneHVAC:RefrigerationChillerSet, !- Zone Equipment 1 Object Type
SubFreezerChillerSet, !- Zone Equipment 1 Name
1, !- Zone Equipment 1 Cooling Sequence
1, !- Zone Equipment 1 Heating or No-Load Sequence
, !- Zone Equipment 1 Sequential Cooling Fraction Schedule Name
; !- Zone Equipment 1 Sequential Heating Fraction Schedule Name
This equipment list is referenced by the zone HVAC equipment connections, which also defines the zone that is connected to that equipment list.
ZoneHVAC:EquipmentConnections,
SubFreezer, !- Zone Name
SubFreezerEquipment, !- Zone Conditioning Equipment List Name
, !- Zone Air Inlet Node or NodeList Name
, !- Zone Air Exhaust Node or NodeList Name
NODE_144, !- Zone Air Node Name
NODE_145; !- Zone Return Air Node or NodeList Name
This zone will then have zone control thermostat objects define the thermostat settings (cooling below -25C).
ZoneControl:Thermostat,
SubFreezer Thermostat, !- Name
SubFreezer, !- Zone or ZoneList Name
Zone Control Type Sched Dual YearRound, !- Control Type Schedule Name
ThermostatSetpoint:DualSetpoint, !- Control 1 Object Type
Dual Setpoint Blast Freeze; !- Control 1 Name
ThermostatSetpoint:DualSetpoint,
Dual Setpoint Blast Freeze, !- Name
Heating Setpoints_BlastFreeze, !- Heating Setpoint Temperature Schedule Name
Cooling Setpoints_BlastFreeze; !- Cooling Setpoint Temperature Schedule Name
Schedule:Compact,
Cooling Setpoints_BlastFreeze, !- Name
Temperature, !- Schedule Type Limits Name
Through: 12/31, !- Field 1
For: AllDays, !- Field 2
Until: 7:00,-25., !- Field 3
Until: 20:00,-25., !- Field 5
Until: 24:00,-25.; !- Field 7
For your case, you want to make two changes to this example:
EDIT
I should also mention that the cutout temperature input is applied to the heating setpoint as well as the cooling setpoint. This is explained in the following psuedo code from the Input Output Reference section for the cutout temperature input field:
4 - Dual Setpoint (Heating and Cooling) with deadband
If ( MAT < HeatingSetpoint )
HeatingSetpoint = HeatingSetpoint + DeltaT
CoolingSetpoint = No change
Else If ( MAT > CoolingSetpoint )
HeatingSetpoint = No change
CoolingSetpoint = CoolingSetpoint - DeltaT
Else
No change
End If
Because of this, the documentation goes on to provide the following recommendations and notes:
1. The heating and cooling setpoints must be separated by at least 2 times the Temperature Difference Between Cutout And Setpoint or there will be a fatal error.
2. The thermostat setpoint not met hours are incorrect with this option.
3. This option will cause excess operation of heat pump system supplemental heating coils.
Your severe error is related to note #1. It sounds like you've set the heating thermostat setpoint to -22C, so when cooling is needed the adjusted cooling thermostat setpoint is also -22C. Try lowering the heating thermostat setpoint while keeping the cutout temperature of 4C and run a new simulation.
