Pump - Variable Speed

 

Pump:VariableSpeed

 

 

Used in:

 

Plant and Condenser loops

General

Name

The auto-generated name for the pump.

Type

The type of the variable speed pump is fixed as:

 

 

To change from variable speed to constant speed you most open the parent Plant or Condenser loop dialog and change the Plant loop flow type to 1-Constant flow.

Pump Settings

Design power consumption

This numeric field contains the pump’s rated power consumption (in W). If the user is performing a pressure simulation on the loop in which this pump is found, this value would only be used to estimate pump efficiency. During reported calculations, the pump would use the loop pressure drop and current flow conditions along with efficiency to calculate pump power dynamically.

Design pump head

This numeric field contains the pump’s rated head pressure (in Pascals or ftH2O).

Important Note: The default pump head provided by the Plant and Condenser Loop templates is 20,000 Pa. This may be suitable for a small building, but it is important that you enter the correctly sized pump head if you wish to simulate pump energy consumption accurately in your model.

Design maximum flow rate (hidden)

This numeric field contains the pump’s rated volumetric flow rate (in m3/s or gal/min). This setting comes from the Plant loop Maximum loop flow rate and cannot be accessed.

Design minimum flow rate

This field contains the minimum volumetric flow rate while operating in variable flow capacity rate (in m3/s or gal/min).

Motor efficiency

This numeric field contains the pump’s efficiency in decimal form (0 = 0%, 1 = 100%).

Fraction of motor inefficiencies to fluid stream

This numeric field contains the pump’s fraction of power loss to the fluid.

Pump control type

This is a choice field of:

 

A variable speed pump is defined with maximum and minimum flow rates that are the physical limits of the device. If there is no load on the loop and the pump is operating intermittently, then the pump can shutdown. For any other condition such as the loop having a load and the pump is operating intermittently or the pump is continuously operating (regardless of the loading condition), the pump will operate and select a flow somewhere between the minimum and maximum limits. In these cases where the pump is running, it will try to meet the flow request made by demand side components.

Part Load Performance

Pump curve template

Use the pump curve template to load some pre-defined pump coefficients to the dialog.

Pump Coefficients

The fraction of full load power is determined during the simulation by the cubic equation:

 

FractionFullLoadPower = C1 + C2. PLR + C3 PLR2 + C4.PLR3

 

where C1to C4are the coefficients described below and PLR is the Part Load Ratio.

Coefficient 1 of the part load performance curve

This numeric field contains the first coefficient, C1, in the part load ratio curve.

Coefficient 2 of the part load performance curve

This numeric field contains the second coefficient, C2, in the part load ratio curve.

Coefficient 3 of the part load performance curve

This numeric field contains the third coefficient, C3, in the part load ratio curve.

Coefficient 4 of the part load performance curve

This numeric field contains the fourth coefficient, C4, in the part load ratio curve.

Pump - Variable Speed Outputs

HVAC,Average,Pump Electric Power [W]

HVAC,Sum,Pump Electric Consumption [J]

HVAC,Average,Pump Shaft Power [W]

HVAC,Average,Pump Heat To Fluid [W]

HVAC,Sum,Pump Heat To Fluid Energy [J]

HVAC,Average,Pump Outlet Temp [C]

HVAC,Average,Pump Mass Flow Rate [kg/s]

Pump Electric Power [W] Pump Electric Consumption [J]

These outputs are the electric power input to the pump motor. Consumption is metered on Pumps:Electricity, Electricity:Plant, and Electricity:Facility.

Pump Shaft Power [W]

This is the shaft power delivered from the motor to the pump.

Pump Heat To Fluid [W]

Pump Heat To Fluid Energy [J]

These outputs are the energy added to the fluid as heat. For the current algorithm, this is equal to Pump Shaft Power, because the loops are closed and all energy added to the fluid will ultimately become heat due to friction.

Pump Outlet Temp [C]

Pump Mass Flow Rate [kg/s]

These outputs are the water outlet temperature and mass flow rate.