P17280: Hot Wheelz Thermal Management System
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Kristin's Work

Table of Contents

Preliminary Detailed Design Deliverables

Individual Deliverables
Title Date Due Date Completed
Preliminary Heat Sink Design 10/17/16 10/17/16
Heat Sink Simulation 11/1/16 10/31/16
Determine if Fins are Needed 11/3/16 11/3/16
Detailed Heat Sink Drawing 11/3/16 11/2/16
Heat Sink Mounting Location 11/3/16 11/2/16

Preliminary Design Work

Heat Sink Thickness Calculations - File

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Calculations were done for heat sinks ranging from 0.039 inches to 0.354 inches thick. The temperature difference between these thicknesses was less than 0.5F. The estimated surface temperature is 70C, or 158F. This is consistent with other estimates from hand calculations and simulations.

Solidworks Simulation

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A simulation was done in Solidworks to confirm the calculated data above and to obtain a temperature gradient across the plate. As seen in the above spreadsheet, the temperature through the plate is approximately the same due to aluminium's very low thermal resistance.

The temperature will be highest in the center of the plate, where the controller sits. The lowest temperature is 120F at the edges farthest away from the controller, and 152F in the center.

The steady state temperature range shown by this model implies that the controller’s temperature will never be within 20 degrees of the temperature at which performance begins to degrade (185F).

These results also imply that we don’t need to utilize fins in our design. Although fins will make heat transfer more efficient, they are not necessary to keep our controller within our desired temperature range.

Detailed Drawing

public/User/Kristin/heatsink_drawing.PNG

The heat sink is made of 6061-T6 Aluminium and is 12" X 12" X 0.25". There are 4 thru holes for mounting the heat sink to the frame, and 4 thru holes for mounting the controller to the heat sink. The holes are not tapped.

Location

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The controller will most likely be mounted on the back end of the vehicle. This is the same location that it was mounted in last year. However, this location is not final because we are waiting on final design information from the Hot Wheelz Team.

We want to place the motor here because it allows the team to have easy access to the controller, and allows airflow to pass over both the controller and the heat sink. If more air cools the controller itself, more heat will be removed due to convection as opposed to more heat going through the heat sink. The downside of this design is that the connections would be more likely to be exposed to water. This can be alleviated by shrink wrapping the connections and covering them with corrosion spray.

The other option is to mount the controller upside down in the spot that it is currently placed. This would allow more air to flow over the heat sink itself, and less air to flow over the controller. The problem with this design is that there is not a lot of room in that spot, and the controller and wires could interfere with the differential.

Efficiency

Phase 3 Efficiency
Time Spent Projected Time Efficiency
2000 mins 1000 mins 50%

Detailed Design Deliverables

Individual Deliverables
Title Date Due Date Completed
something
Heat Sink Simulation
Determine if Fins are Needed
Detailed Heat Sink Drawing
Heat Sink Mounting Location

Preliminary Design Work

Efficiency

Phase 3 Efficiency
Time Spent Projected Time Efficiency
2000 mins 1000 mins 50%