Spray Cooling Heat Transfer [Input Data]

Spray cooling is when a fluid is passed down a duct in the shaft and then is sprayed at the end-winding and/or rotor via nozzles. This fluid then drains out of the end-winding and/or rotor and flows over various surfaces on the inside of the machine (giving some extra cooling) and is drained out of the machine.

The spray cooling method cannot be used at the same time as Wet Rotor.

The Spray Coolingcheckbox should be checked in Cooling Options [Input Data Editor] to choose to use the Spray Cooling method.

The nozzle position and sizes are defined using the Spray Cooling Fluid Flow editor.

The Spray Cooling editor is then available to set data such as:

Inlet Temperature

Edit box for setting the spray cooling fluid inlet temperature.

Fluid Volume Flow Rate

Edit box for setting the spray cooling fluid volume flow rate.

Fluid Properties:

Edit boxes for setting the Spray Cooling fluid thermal conductivity, density, specific heat capacity and kinematic viscosity.

Outputs showing calculated values of the Spray Cooling fluid dynamic viscosity and Prandtl Number.

The Spray Cooling fluid properties can be either fixed values shown in the table or can have properties that are dependent on temperature when the fluid is taken from the fluids database.

Spray Cooling Table Editor

The Spray Cooling Table Editor used to input/calculate/display the motors spray cooling heat transfer data. It has the following columns:

  • Component - description of motor component surface that can dissipate heat by convection
  • Input h?* - Check-box for choosing to input or calculate h[wet-rotor] for the particular motor component surface
  • Convection Correlation - Indication of the Spray Cooling Convection Correlation formulation used to calculate h of the particular motor component surface
  • h[input] or h[adjust]* [W/m2/C or dimensionless] - Depending upon the check-box in column Input h?, the forced convection heat transfer coefficient (h) can be input directly or an adjustment multiplier input - this being used to modify the calculated value of h
  • Local Velocity Multiplier* [pu] - Multiplier used in determining the local fluid velocity.
  • Local Fluid Velocity [m/s] - Local fluid velocity.
  • Re[Imp] [dimensionless] - Impingement Reynolds Number for spray target or Re for channel/plate. See Spray Cooling Convection Correlation
  • Re[Wall] [dimensionless] - Wall Jet Reynolds Number for spray target or Re for channel/plate. See Spray Cooling Convection Correlation
  • Nu[Imp] [dimensionless] - Impingement Nusselt Number for spray target or Nu for channel/plate. See Spray Cooling Convection Correlation
  • Nu[Wall] [dimensionless] - Wall Nusselt Number for spray target or Nu for channel/plate. See Spray Cooling Convection Correlation
  • Area Multiplier* [pu] - Multiplier used in determining the sprayed area.
  • Sprayed Area - the surface area of the component.
  • h [W/m2/C] - Wet Rotor Convection Heat Transfer Coefficient, h, input in table or calculated using the Spray Cooling Convection Correlation (Depending upon the contents of the Input h? check-box)
  • Notes* - User notes for table row

N.B. - Parameters marked by * are inputs, all others are outputs.

See also Spray Cooling Fluid Flow [Input Data]