Modeling Strategies for Fluorescent Applications

The objectives of most fluorescent lighting applications include the following:

• To the determine if the environment temperature surrounding the fixture exceeds known limits.
• To ensure the heat dissipated from the lamp does not overheat the socket and ballast.

Modeling Guidelines

• Simplify the socket geometry in the CAD model.
• Model the fixture either in an installed configuration or within a test environment.
  • To model the fixture as installed, use the appropriate modeling strategy.
  • If the fixture is very close to the ceiling, and air cannot physically flow upward from the mounting box, it may be necessary to close the top boundary:
    1. Assign the ambient temperature and pressure = 0 only to the bottom surface.
    2. Do not assign a pressure boundary condition to the top surface.
  • To model the fixture in a test environment, use the Test box configuration.
• Include the glass tube in the geometric model, and use its physical thickness.

Material Considerations

• Assign a solid material to the gas inside the tube. Specify the conductivity to be that of the gas inside the tube.

Heat Loading

• The fluorescent input power is the product of Voltage and current. Typically, 15-35% of the input power is dissipated as heat (the rest is light).
• Apply a heat generation boundary condition to the gas "solid" within the tube that is between 15 and 35% of the power supplied to the fluorescent tube.

LED |Unit 3