ZoneHVAC:PackagedTerminalAirConditioner
Used in:
HVAC Zones
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Used in:
HVAC Zones |
The packaged terminal air conditioner (PTAC) is a compound object made up of other components. Each PTAC consists all of these fixed components:
To change the type of heating coil you should edit the heating coil component and select the required coil type from the Heating coil dialog.
Note: The details of the DX cooling system including compressor, condenser, CoP, part-load performance etc are entered on the DX cooling coil dialog.
Default settings are assigned to these components at the point the PTAC is created and these can be overridden by editing the individual component properties.
While the figure below shows the PTAC with draw through fan placement, blow through fan placement can also be modelled by positioning the supply air fan between the outdoor air mixer and the DX cooling coil. The packaged terminal air conditioner coordinates the operation of these components and is modelled as a type of zone equipment.
Schematic of a Packaged terminal air conditioner with draw through fan placement
A unique system-assigned name for an instance of a packaged terminal air conditioner. Any reference to this air conditioner by another object will use this name.
There are 2 fan placement options:
Two fan operation modes are available for selection in PTAC units:
This data specifies the supply air fan operating mode schedule. The supply air fan operating mode may vary during the simulation based on time-of-day or with a change of season. Schedule values of 0 denote that the supply air fan and the heating or cooling coil cycle on and off together to meet the heating or cooling load (aka AUTO fan). Schedule values other than 0 indicate that the supply fan runs continuously while the heating or cooling coil cycles to meet the load.
The default schedule is "Fan operation mode - Continuous" with a constant value of 1, i.e. that the supply fan runs continuously while the heating or cooling coil cycles to meet the load at all times. To obtain the AUTO fan configuration, select the "Fan operation mode - Cycling" schedule which has a constant value of 0.
To set up a time-varying fan operation mode, create and select a schedule with values of 0 and 1 to define the way the fan operation mode varies in time.
This numeric field defines the supply air flow rate leaving the air conditioner (in m3/s or ft3/min) when the DX cooling coil is operating. Values must be greater than 0 or this field is autosizable.
This numeric field defines the supply air flow rate leaving the air conditioner (in m3/s or ft3/min) when the heating coil is operating. Values must be greater than 0 or this field is autosizable.
This numeric field defines the supply air flow rate leaving the air conditioner (in m3/s or ft3/min) when neither cooling nor heating is required (i.e., DX coil and heater are off but the supply air fan operates). This field is only used when the air conditioner’s supply air fan operating mode schedule specifies continuous fan operation. Values must be greater than or equal to zero, or this field is autosizable. If the air conditioner’s supply air fan operating mode schedule specifies continuous fan operation and this value is set to zero or this field is left blank, then the model assumes that the supply air flow rate when no cooling/heating is needed is equal to the supply air flow rate when the cooling or heating coil was last operating (for cooling operation or heating operation).
If the PTAC provides outdoor air then check this option.
This numeric field defines the outdoor air flow rate through the air conditioner (in m3/s or ft3/min) when the DX cooling coil is operating. Values must be greater than or equal to 0, or this field is autosizable. Note that the outdoor air flow rate during cooling operation is fixed; it cannot change during the simulation. In addition, the outdoor air flow rate during cooling operation cannot be greater than the air conditioner’s supply air volumetric flow rate during cooling operation.
This numeric field defines the outdoor air flow rate through the air conditioner (in m3/s or ft3/min) when the heating coil is operating. Values must be greater than or equal to 0, or this field is autosizable. Note that the outdoor air flow rate during heating operation is fixed; it cannot change during the simulation. In addition, the outdoor air flow rate during heating operation cannot be greater than the air conditioner’s supply air volumetric flow rate during heating operation.
This numeric field defines the outdoor air flow rate through the air conditioner (in m3/s or ft3/min) when neither cooling nor heating is required (i.e., cooling and heating coils are off but the supply air fan operates). Values must be greater than or equal to 0, or this field is autosizable.
Note that the outdoor air flow rate when no cooling/heating is needed is fixed; it cannot change during the simulation. In addition, the outdoor air flow rate when no cooling/heating is needed cannot be greater than the air conditioner’s supply air volumetric flow rate when no cooling/heating is needed. This field is only used when the air conditioner’s supply air fan operating mode schedule specifies continuous fan operation. If the air conditioner’s supply air fan operating mode schedule specifies continuous fan operation and the field ‘Supply air volumetric flow rate when no cooling or heating is needed’ is set to zero or is left blank, then the model assumes that the outdoor air flow rate when no cooling/heating is needed is equal to the outdoor air flow rate when the cooling or heating coil was last operating (for cooling operation [i.e., Outdoor air Flow rate during cooling operation] or heating operation [i.e., Outdoor air flow rate during heating operation]) and this field is not used.
Select the Schedule that defines whether the air conditioner can run during a given time period. A schedule value greater than 0 (usually 1 is used) indicates that the air conditioner can be on during a given time period. A value less than or equal to 0 (usually 0 is used) denotes that the air conditioner is off. This schedule may be used to completely disable the air conditioner (all of its coils and the supply air fan) as required.
HVAC,Average,Packaged Terminal Air Conditioner Total Zone Heating Rate[W]
HVAC,Sum,Packaged Terminal Air Conditioner Total Zone Heating Energy[J]
HVAC,Average,Packaged Terminal Air Conditioner Total Zone Cooling Rate[W]
HVAC,Sum,Packaged Terminal Air Conditioner Total Zone Cooling Energy[J]
HVAC,Average,Packaged Terminal Air Conditioner Sensible Zone Heating Rate[W]
HVAC,Sum,Packaged Terminal Air Conditioner Sensible Zone Heating Energy[J]
HVAC,Average,Packaged Terminal Air Conditioner Sensible Zone Cooling Rate[W]
HVAC,Sum,Packaged Terminal Air Conditioner Sensible Zone Cooling Energy[J]
HVAC,Average,Packaged Terminal Air Conditioner Latent Zone Heating Rate[W]
HVAC,Sum,Packaged Terminal Air Conditioner Latent Zone Heating Energy[J]
HVAC,Average,Packaged Terminal Air Conditioner Latent Zone Cooling Rate[W]
HVAC,Sum,Packaged Terminal Air Conditioner Latent Zone Cooling Energy[J]
HVAC,Average,Packaged Terminal Air Conditioner Electric Power[W]
HVAC,Sum,Packaged Terminal Air Conditioner Electric Consumption[J]
HVAC,Average,Packaged Terminal Air Conditioner Fan Part-Load Ratio
HVAC,Average,Packaged Terminal Air Conditioner Part-Load Ratio
This output field is the total (enthalpy) heat addition rate of the packaged terminal air conditioner to the zone it is serving in Watts. This value is calculated using the enthalpy difference of the air conditioner outlet air and inlet air streams, and the air mass flow rate through the air conditioner. This value is calculated for each HVAC system timestep being simulated, and the results (enthalpy addition only) are averaged for the timestep being reported.
This output field is the total (enthalpy) heat addition of the packaged terminal air conditioner to the zone it is serving in Joules over the timestep being reported. This value is calculated using the enthalpy difference of the air conditioner outlet air and inlet air streams, the air mass flow rate through the air conditioner, and the HVAC simulation timestep. This value is calculated for each HVAC system timestep being simulated, and the results (enthalpy addition only) are summed for the timestep being reported.
This output field is the total (enthalpy) heat extraction rate of the packaged terminal air conditioner from the zone it is serving in Watts. This value is calculated using the enthalpy difference of the air conditioner outlet air and inlet air streams, and the air mass flow rate through the air conditioner. This value is calculated for each HVAC system timestep being simulated, and the results (enthalpy extraction only) are averaged for the timestep being reported.
This output field is the total (enthalpy) heat extraction of the packaged terminal air conditioner from the zone it is serving in Joules over the timestep being reported. This value is calculated using the enthalpy difference of the air conditioner outlet air and inlet air streams, the air mass flow rate through the air conditioner, and the HVAC simulation timestep. This value is calculated for each HVAC system timestep being simulated, and the results (enthalpy extraction only) are summed for the timestep being reported.
This output field is the sensible heat addition rate of the packaged terminal air conditioner to the zone it is serving in Watts. This value is calculated using the enthalpy difference of the air conditioner outlet air and inlet air streams at a constant humidity ratio, and the air mass flow rate through the air conditioner. This value is calculated for each HVAC system timestep being simulated, and the results (heating only) are averaged for the timestep being reported.
This output field is the sensible heat addition of the packaged terminal air conditioner to the zone it is serving in Joules over the timestep being reported. This value is calculated using the enthalpy difference of the air conditioner outlet air and inlet air streams at a constant humidity ratio, the air mass flow rate through the air conditioner, and the HVAC simulation timestep. This value is calculated for each HVAC system timestep being simulated, and the results (heating only) are summed for the timestep being reported.
This output field reports the moist air sensible heat extraction rate of the packaged terminal air conditioner from the zone it is serving in Watts. This value is calculated using the enthalpy difference of the air conditioner outlet air and inlet air streams at a constant humidity ratio, and the air mass flow rate through the air conditioner. This value is calculated for each HVAC system timestep being simulated, and the results (cooling only) are averaged for the timestep being reported.
This output field reports the moist air sensible heat extraction of the packaged terminal air conditioner from the zone it is serving in Joules over the timestep being reported. This value is calculated using the enthalpy difference of the air conditioner outlet air and inlet air streams at a constant humidity ratio, the air mass flow rate through the air conditioner, and the HVAC simulation timestep. This value is calculated for each HVAC system timestep being simulated, and the results (cooling only) are summed for the timestep being reported.
This output field is the latent heat addition (humidification) rate of the packaged terminal air conditioner to the zone it is serving in Watts. This value is calculated as the difference between the total energy rate and the sensible energy rate provided by the packaged terminal air conditioner. This value is calculated for each HVAC system timestep being simulated, and the results (latent heat addition only) are averaged for the timestep being reported.
This output field is the latent heat addition (humidification) of the packaged terminal air conditioner to the zone it is serving in Joules over the timestep being reported. This value is calculated as the difference between the total energy delivered to the zone and the sensible energy delivered to the zone by the packaged terminal air conditioner. This value is calculated for each HVAC system timestep being simulated, and the results (latent heat addition only) are summed for the timestep being reported.
This output field is the latent heat extraction (dehumidification) rate of the packaged terminal air conditioner from the zone it is serving in Watts. This value is calculated as the difference between the total energy rate and the sensible energy rate provided by the packaged terminal air conditioner. This value is calculated for each HVAC system timestep being simulated, and the results (latent heat extraction only) are averaged for the timestep being reported.
This output field is the latent heat extraction (dehumidification) of the packaged terminal air conditioner from the zone it is serving in Joules over the timestep being reported. This value is calculated as the difference between the total energy delivered to the zone and the sensible energy delivered to the zone by the packaged terminal air conditioner. This value is calculated for each HVAC system timestep being simulated, and the results (latent heat extraction only) are summed for the timestep being reported.
This output field is the electricity consumption rate of the packaged terminal air conditioner in Watts. The consumption includes electricity used by the compressor (including crankcase heater), fans (indoor supply air fan and the condenser fan), and the heating coil (includes electricity consumption rate for electric heating coil or parasitic electricity consumption rate for non-electric coils). This value is calculated for each HVAC system timestep being simulated, and the results are averaged for the timestep being reported.
This output field is the electricity consumption of the packaged terminal air conditioner in Joules for the time period being reported. The consumption includes electricity used by the compressor (including crankcase heater), fans (indoor supply air fan and the condenser fan), and the heating coil (includes electricity consumption for electric heating coil or parasitic electricity consumption for non-electric coils). This value is calculated for each HVAC system timestep being simulated, and the results are summed for the timestep being reported.
This output field is the part-load ratio of the fan. The fan part-load ratio is defined as the average supply air mass flow rate divided by the maximum supply air mass flow rate. The maximum supply air mass flow rate depends on whether heating, cooling, or no heating or cooling is required during the timestep. This value is calculated for each HVAC system timestep being simulated, and the results are averaged for the timestep being reported.
This output field is the part-load ratio used by the coils (cooling and heating). Part-load ratio is defined as the total coil load divided by the coil steady-state capacity. This value is calculated for each HVAC system timestep being simulated, and the results are averaged for the timestep being reported.