Fabrication, Calibration and Testing of a Transient Hot-Wire

Thermal Conductivity Apparatus for

Nanosilica-in-Fluid Dispersion (Nanofluids)

Sheryl Lynn B. Flores¹, Adrian Augusto M. Sumalde²,Ma. Cristine Concepcion D. Ignacio³,

John Paolo A. Ramoso⁴, and Aryan Paula A. Manalo⁴

ABSTRACT

The field of nanotechnology is developing at an increasing rate, and studies have been focused in characterizing the properties of nanomaterials in order to further their applications. In this study, a Wheatstone bridge network was incorporated along with a thermal conductivity cell setup in order to determine the thermal conductivity of nanofluids with a certain degree of accuracy and          precision. The Wheatstone bridge is balanced using a DC electronic load, and with the measured voltage output and resistance values, the temperature change of a platinum hot-wire is calculated using voltage divider rule. The slope of the temperature change with respect to time in the         logarithmic scale is used to compute the thermal conductivity of the fluid. The fabricated            apparatus is calibrated using distilled water, with the obtained percent error between measured and standard values ranging from 0.0019% to 1.015%. Further validation of the apparatus was done statistically, with the results supporting the accuracy of the fabricated apparatus. Finally, the apparatus was tested to determine the conductivity of several test fluids composed of ethylene glycol (EG), water and nanosilica (NS), and its precision was validated with repeated measurements on a specific nanofluid 25 EG, 75 H2O 0.25% NS.

Keywords: nanofluids, transient hot-wire, thermal conductivity, Wheatstone bridge

Citation:

Flores, S.L.B, Sumalde, A.A.M, Ignacio, M.C.C.D., Ramoso, J.P.A., and Manalo, A.P.A. (2017). Fabrication, Calibration and Testing of a Transient Hot-Wire Thermal Conductivity Apparatus for Nanosilica-in-Fluid Dispersion (Nanofluids).  Philippine Journal of Agricultural and Biosystems Engineering, (13):42-50.

¹BS Electrical Engineering Graduate, College of Engineering and Agro-Industrial Technology, University of the Philippines Los Baňos, 4031 College, Laguna, Philippines

²Assistant Professor, Department of Electrical Engineering, College of Engineering and Agro-Industrial Technology,        University of the Philippines Los Baños, 4031 College, Laguna, Philippines

³Assistant Professor, Agricultural and Bio-Process Division, Institute of Agricultural Engineering, College of Engineering and Agro-industrial Technology, University of the Philippines Los Baños, 4031 College, Laguna, Philippines

⁴Instructor, Department of Electrical Engineering, College of Engineering and Agro-Industrial Technology, University of the Philippines Los Baños, 4031 College, Laguna, Philippines.