Experimental Design And Development Of A Transient Hot-wire Appartus To Measure Fluid Thermal Conductivity

Abstract

The thermal conductivity of heat transfer fluids (HTF) is a critical parameter to determine the overall heat transfer of thermal energy storage systems. With the idea to enhance heat transfer of HTFs, measuring thermal conductivity is vital. With different approaches to measure thermal conductivity, the transient hot-wire method (THWM) was the selected technique due to eliminating convection to extract accurate thermal conductivity values of measured fluids. As the THWM has a fully defined theory of extracting thermal conductivity, this thesis aims to illustrate the design and implementation of the custom-designed apparatus. Material procurement and special techniques to utilize a 25 μm diameter platinum wire was possible to develop a THW test bench. Air, isopropyl alcohol (IPA), ethanol, and DI water were tested as base fluids. Experimental results show that the percent error of detecting their thermal conductivities ranged from 0.117-4.772% in experimental error compared to literature values. The overall thesis shows that the developed THW apparatus can determine thermal conductivity values from 0.026 W/mK to 0.73 W/mK for fluids. With the THW test cell capable to detect the thermal conductivity of liquids and gases, this opens to measuring other liquid solutions that are known for their enhanced thermal conductivity values via nanofluids.