Session: 12-06-04: Advanced Heat Sinks and Emerging Thermal Applications

Paper Number: 166299

Study of Composite Materials for Cooling Systems With Variable Heat Generation 

Phase Change Materials, or PCMs, are commonly used for thermal energy storage and maintaining stable temperatures.  While they have high latent heat, allowing a large amount of heat to be absorbed without changing phase, they fail in their typically low thermal conductivity of around 0.2-0.3 W/m∙K.  Metal foams have been known to drastically increase the thermal conductivity of PCM as they possess higher thermal conductivities, thus leading to more effective heat transfer.  However, not only does the thermal conductivity change when metal foam is introduced, but other properties such as density, specific heat, and latent heat also change and affect the heat transfer of the composite material.  In the present study, the effect of the output temperatures based on changing each of these factors individually based on porosity of either 50%, 75%, or 99% aluminum foam is investigated. The cylindrical heating system consisted of an AISI type 304 stainless-steel shaft, which has a thermal conductivity of 14.9 W/m·K, and a 12V 40W electrical heater placed in the middle of the cylinder.  The stainless-steel shaft is 26mm in diameter and has a height of 65mm. It will be shown if specific patterns can be determined based on these variable values and which property affects the temperature output to the most significant degree. The study includes experimental data from aluminum foam’s standalone heating properties without PCM. Thermocouples were placed at specific locations throughout the block to record temperatures versus time. The test measured the effects of different heat rate generation and external airflow velocities for a forced convection cooling system. A cross-shaped aluminum foam with a low priority was tested at other positions. The heat source produced temperatures ranging from 45°C to 140°C under varying conditions. The experiment also included rectangular aluminum foam blocks impregnated with eicosane, consisting of a new composite material with new thermal properties. A heater and thermocouples were embedded into the composite material. Electric power was supplied to the composite material under two circumstances: the thermocouple reached the eicosane’s melting temperature, the eicosane fully melted, or there was no significant change in temperature over time. After the electric power was off, the solidification time was recorded and then heated again, generating a cycle repeated two more consecutive times. Tests were conducted at different power rates with aluminum foam blocks with varying pores per inch (PPI). The preliminary experimental results showed that the composite could withstand more prolonged test heating and cooling process cycles

Presenting Author: Ethan Trulson MIELKE

Presenting Author Biography: Gerardo Carbajal is an associate professor in the Mechanical Engineering Department at Florida Polytechnic University in Lakeland, FL. He joined Florida Poly in 2019 after spending several years as a full professor at the Ana G. Mendez University System (AGMUS) Gurabo-Campus in Puerto Rico. Gerardo Carbajal completed his PhD in Mechanical Engineering at the Rensselaer Polytechnic Institute in Troy, NY. He has published peer-reviewed journal and conference papers and co-organized the NSF wind energy and turbulence workshop in Puerto Rico in 2011. His research focuses on heat pipe applications and numerical simulations (CFD), flow boiling in mini and microchannels, hybrid cooling systems for applications in Li-Ion batteries, heat transfer enhancement, and thermal and water management of PEMFC. Notable honors include being nominated two times for being Nominated to the ABLAZE Research Award 2022- Florida Polytechnic University, March 2022 and March 2024, and the Frederic Douglas Award For Exceptional Leadership, Blue Integrated Partnership (BIP)-Purdue University, UPR-Bayamon, in 2023. Also, he delivered keynote and inaugural addresses at international conferences. His professional background includes a fellowship with DOE-NETL and recognition from the National Wing Renewable Center at Texas Tech University.

Authors:

Gerardo Carbajal Florida Polytechnic University
Ethan Trulson MIELKE
Emily Geiger Florida Polytechnic University