# Thermal Performance of Fractal Fins in a Vacuum Environment

## Location

Atrium

## Session Format

Poster Presentation

## Research Area Topic:

Engineering and Material Sciences - Mechanical

## Co-Presenters and Faculty Mentors or Advisors

Dr. David Calamas, Faculty Advisor

Dr. Gustavo Molina, Faculty Advisor

## Abstract

The thermal performance of fractal fins in a vacuum chamber was experimentally investigated. A fractal is an infinite pattern that repeats itself at different scales. Fractals have the property of self-similarity across different scales. This research investigated the thermal performance of fractal fins in a vacuum environment, which simulated the application of heat sinks and thermal radiators in space. Increasing the surface area is desirable as the rate of heat transfer is directly proportional to the surface area. Decreasing the mass of heat sink fins or thermal radiators is desirable for weight savings in aerospace applications used to cool electronics and provide thermal control of crewed spaces. When certain fractal patterns, like the Seirpinski carpet pattern utilized in this study, are used in the design of fins, an increase in surface area coupled with a decrease in mass can be achieved. The objective of this research was to determine the fin efficiency, fin effectiveness, and effectiveness per unit mass for fractal fins in a vacuum where radiation heat transfer is the only heat rejection mechanism. Radiation heat transfer differs from other forms of heat transfer in that it does not require a medium and therefore can occur in high-vacuum conditions such as outer space. For the experiment, a uniform heat rate was applied to the base of the fractal fins using flexible, thin-film heaters to produce a temperature difference. The base temperature of the fractal fin was measured using surface-mounted thermocouples inside the vacuum chamber, while the temperature profile and fin base and tip temperatures were determined with a FLIR infrared camera mounted outside the vacuum chamber. This research sought to determine if the increase in effectiveness per unit mass observed in the natural convection environment was due to the increased surface area of the Sierpinski Carpet fractal pattern. The expected results were that the initial loss of surface area in Fin 1 and 2 would result in a decrease in heat rejection but that the increase in surface area of the other fractal iterations would increase the fin effectiveness and effectiveness per unit mass.

## Keywords

Heat transfer, Vacuum chamber, Thermal radiation, Fins, Electronics cooling

## Presentation Type and Release Option

Presentation (Open Access)

## Start Date

4-24-2015 10:45 AM

## End Date

4-24-2015 12:00 PM

## Recommended Citation

Hines, Philip C., "Thermal Performance of Fractal Fins in a Vacuum Environment" (2015). *GS4 Georgia Southern Student Scholars Symposium*. 41.

https://digitalcommons.georgiasouthern.edu/research_symposium/2015/2015/41

Thermal Performance of Fractal Fins in a Vacuum Environment

Atrium

The thermal performance of fractal fins in a vacuum chamber was experimentally investigated. A fractal is an infinite pattern that repeats itself at different scales. Fractals have the property of self-similarity across different scales. This research investigated the thermal performance of fractal fins in a vacuum environment, which simulated the application of heat sinks and thermal radiators in space. Increasing the surface area is desirable as the rate of heat transfer is directly proportional to the surface area. Decreasing the mass of heat sink fins or thermal radiators is desirable for weight savings in aerospace applications used to cool electronics and provide thermal control of crewed spaces. When certain fractal patterns, like the Seirpinski carpet pattern utilized in this study, are used in the design of fins, an increase in surface area coupled with a decrease in mass can be achieved. The objective of this research was to determine the fin efficiency, fin effectiveness, and effectiveness per unit mass for fractal fins in a vacuum where radiation heat transfer is the only heat rejection mechanism. Radiation heat transfer differs from other forms of heat transfer in that it does not require a medium and therefore can occur in high-vacuum conditions such as outer space. For the experiment, a uniform heat rate was applied to the base of the fractal fins using flexible, thin-film heaters to produce a temperature difference. The base temperature of the fractal fin was measured using surface-mounted thermocouples inside the vacuum chamber, while the temperature profile and fin base and tip temperatures were determined with a FLIR infrared camera mounted outside the vacuum chamber. This research sought to determine if the increase in effectiveness per unit mass observed in the natural convection environment was due to the increased surface area of the Sierpinski Carpet fractal pattern. The expected results were that the initial loss of surface area in Fin 1 and 2 would result in a decrease in heat rejection but that the increase in surface area of the other fractal iterations would increase the fin effectiveness and effectiveness per unit mass.