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Applied Physics A, February 2013, Volume 110, Issue 2, pp 403-412
Nathan Van Velson, Xinwei Wang.
Department of Mechanical Engineering, Iowa State University, 2010 Black Engineering Building, Ames, IA, 50011, USA
Abstract
A contact transient electrothermal technique (CTET) is developed to characterize the thermal transport between one-dimensional conductive and nonconductive microscale wires that are in point contact. This technique is a significant advance from the transient electrothermal method that is used to characterize the thermophysical properties of individual one-dimensional micro-wires. A steady-state analytical solution and a transient numerical solution are used to independently determine the value for the thermal contact resistance between the wires at the contact point. The CTET technique is applied to measurement of the thermal contact resistance between crossed Pt wires (25.4 um diameter) and the thermal contact resistance between a glass fiber (8.9 um diameter) in contact with a Pt wire (25.4 um diameter). For Pt wire contact, the thermal contact resistance increases from 8.94×104 to 7.05×105 K/W when the heating current changes from 20 to 50 mA. For the Pt/glass fiber contact, the thermal contact resistance is much larger (2.83×106 K/W), mainly due to the smaller area at the contact point.
Additional information:
This work reports on the first methodology and experimental implementation to characterize the thermal contact resistance of a single contact between two wires of micro-scale diameter. Such zero-dimensional thermal characterization and the resulting thermal contact resistance are critical for understanding and design of thermal transport across materials composed of fibers. Examples include cloth design for optimized human comfortability and thermal insulation/protection in thermally hostile environment (fire fighter clothes). Furthermore, a wide spectrum of technologies have been developed in the Micro/Nanoscale Thermal Science Laboratory (http://www3.me.iastate.edu/wang/) to measure the thermal conductivity/diffusivity of 1) fiber-like materials and free-standing films of any diameter/thickness and material type, and 2) coatings of any material type with a thickness from sub-mm down to sub-micrometer.
