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Uncertainty Analysis of Thermal Conductivity Measurement by a Homemade Apparatus

In 2008 a homemade apparatus was designed and built to determine the conductivity of a variety of metal test samples. It has been in use every semester since then in the Heat Transfer Lab for Mechanical Engineering Technology (MET) students at XXXXX. The device is specifically designed and built for this purpose, and it provides repeatable data when used for its intended function. Even though the results are repeatable, they are not particularly accurate. However, the conductivities found for the metals are close enough for the students in an undergraduate MET course in heat transfer to be able to learn from the exercise. Possible sources of error can be discussed in class, which helps to enhance the students understanding of the overall exercise. The design of the device is similar to a device that is used for the measurement of conductivity of thermal interface materials in industry. It is now being used as a research tool to try to measure the conductivity of plastic and composite materials. Since this device is being used for an unintended purpose it was decided that we should take a closer look at possible sources of error and improvements that might be made to mitigate some of those errors. This paper presents a brief overview of the basic function of the device, including a qualitative discussion of some of the likely sources of error. Then, it includes a discussion of the procedure for measuring the conductivity of plastic and composite materials, also with a qualitative discussion of likely sources of error. The main purpose of the paper is to present a quantitative uncertainty analysis of the thermal conductivity measurement for both the metal samples and for the plastic and composite materials. The paper concludes with thoughts on possible changes that could be made to improve the accuracy of the existing device.