Akademik Veri Yönetim Sistemi
Measurement Science and Technology, cilt.36, sa.6, 2025 (SCI-Expanded, Scopus)
The goal of this study is to develop an automatic balancing method for the accurate detection of harmonics in the 3omega hot wire (3ωHW) method for the thermal conductivity measurement of liquids. To detect harmonics, an essential requirement is the elimination of the fundamental voltage on bridge output caused by the excitation. For this purpose, a closed-loop control circuit exploiting a digitally controlled potentiometer was designed and an application-specific algorithm was developed to manage the bridge balancing automatically. The developed method was then integrated into the conventional 3ωHW method to eliminate uncertainties in the manual balancing process. Following, the performance tests were carried out with the auto-balanced 3ωHW setup in the dynamic range of thermal conductivity 0.127-0.710 W m−1 K−1, including both base fluids and nanofluids. The ratio between the 3ω voltage and the fundamental one is enhanced from 10−4 to approximately 100 in 3.7 s without any manual adjustment.