Webinars

Upcoming Thermal Conductivity Webinars

C-Therm regularly offers FREE online seminars - or "webinars" - to provide information on new applications and offer participants an opportunity to learn how C-Therm's clients are using the innovative sensor technology. The webinar is a combination of a live powerpoint show presented over the internet, and a conference call with participants. Please browse our listing of live upcoming webinars below or check our library of past  archived webinar recordings .

2019 Webinar Schedule

Date

Time

Topic

Wednesday, July 17 1PM EDT Highlights from ITCC&ITES 2019: Thermal Conductivity Measurements in Nanofluids - Errors Due to Convection

Registration:

Advance registration is required for any listed upcoming webinar. Please click on the Register button below to participate in the upcoming webinar and receive instructions on how to join us online for the event. Please note that if the time is not convenient for your group - C-Therm does offer custom private webinars. Please inquire for further details. Feel free to contact us at info@ctherm.com with any questions.

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Application Highlight: Thermal Performance of Modified Polymeric Heatsinks as an Alternative for Aluminum in Heat Rejection Systems

This webinar will review recent published work from researchers at the Chonbuk National University in South Korea highlighting application of the C-Therm Modified Transient Plane Source (MTPS) technique in characterizing performance of polymer based composite materials as heat transfer medium.

Many studies have been conducted to obtain a viable alternative for metallic compartments in heat exchangers. The present research has been conducted to distinctly reveal the performance characteristics of polymer based composite materials as heat transfer medium. Various prototypes of polymeric fins with different volume fractions for multiwalled-carbon nanotubes, copper as components, and high density polyethylene (HDPE) as a matrix, were fabricated and stacked around copper pipes as an air/water finned-pipe heat exchanger. The thermal performance of each case was tested and compared with those of aluminum fins under the same conditions in a miniature mechanically pumped cooling loop (MPCL). Results indicate that for the airside, the difference between total heat transfer rates of the aluminum heat sink increased more rapidly than that of polymeric cases at the beginning, and became constant when a certain Reynolds number is reached. Further, for the best case of new composite heat sinks, a 451% and 52% enhancement in thermal conductivity and heat rejection were achieved, respectively, compared with the pure HDPE. The thermographic method also was used for better visual comparison among the materials. Finally, numerical simulations using ANSYS Fluent, indicated consistency with the experimental results of heat distribution for each case.

 

Highlights from ITCC&ITES 2019: Thermal Conductivity Measurements in Nanofluids - Errors Due to Convection

This webinar presents the highlights from the 34th International Thermal Conductivity Conference (ITCC) and 22nd International Thermal Expansion Symposium (ITES), featureing the guest speaker, Sarah Ackermann from Thermal Analysis Labs.

Since nanofluids were first reported in the early 2000s, they have been the subject of much research. Some early reports presented thermal conductivity (TC) measurement data for nanofluids that showed unusually high values in these materials, far greater than the predictions of the Hamilton-Crosser relation which assumes that heat transfer between filler particles occurs exclusively by diffusion. The large values observed in early nanofluid TC measurements suggests that either the measurement theory or the data is systematically wrong. A detailed examination of the early reports reveals that the risk of error from unaccounted-for convection effects in these tests is significant, owing to very long measurement times employed in the measurements. Analyses by different reviewers have also shown that when the measurement of the thermal conductivity of nanofluids is conducted according to the established best practices for fluid thermal conductivity measurements, the results are consistent with predictions from the Hamilton-Crosser relation.

This report describes the occurrence of convection in nanofluid TC measurements in commonly occurring measurement methodologies and how to mitigate this effect. It discusses the best equipment configurations and experimental procedures for obtaining TC data that is compatible with the assumptions of the Hamilton-Crosser relationship. Finally, it describes a commercially-available TC measurement system, C-Therm’s TCi Thermal Conductivity Analyzer, which uses the Modified Transient Plane Source to address these issues, employing very short test times (less than 1 second), small nanofluid volumes, and a low power heat pulse, to enable testing of fluids without onset of convection. Method validation, both in the form of experimental data and FEM simulation, is provided.

Sarah Ackermann, Applications Specialist at Thermal Analysis Labs