Fabrication and Characterization of Carbon-Based Nanofluids through the Water Vortex Trap Method

Abstract

This study designed an efficient one-step method for synthesizing carbon-based nanofluids (CBNFs). The method employs the vortex trap method (VTM) and an oxygen-acetylene flame, serving as a carbon source, in a manufacturing system of the VTM (MSVTM). The flow rate ratio of O 2 and C 2 H 2 was adjusted to form suitable combustion conditions for the reduced flame. Four flow rate ratios of O 2 and C 2 H 2 were used: 1.5 : 2.5 (V1), 1.0 : 2.5 (V2), 0.5 : 2.5 (V3), and 0 : 2.5 (V4). The morphology, structure, particle size, stability, and basic physicochemical characteristics of the obtained carbon-based nanomaterials (CBNMs) and CBNFs were investigated using transmission electron microscopy, field-emission scanning electron microscopy, X-ray diffraction, Raman spectrometry, ultraviolet-visible-near-infrared spectrophotometry, and a particle size-zeta potential analyzer. The static positioning method was utilized to evaluate the stability of the CBNFs with added EP dispersants. The evaluation results revealed the morphologies, compositions, and concentrations of the CBNFs obtained using various process parameters, and the relation between processing time and production rate was determined. Among the CBNMs synthesized, those obtained using the V4-0 flow rate ratio had the highest stability when no EP dispersant was added. Moreover, the maximum enhancement ratios of the viscosity and thermal conductivity were also obtained for V4-0: 4.65% and 1.29%, respectively. Different types and concentrations of dispersants should be considered in future research to enhance the stability of CBNFs for further application.

Enhanced Heat Transfer Performance of the Tube Heat Exchangers Using Carbon-Based Nanofluids

“…Then, 1.0 wt% CBNF with 1.6 wt% GA was alternately dispersed using an electromagnetic stirrer (PC420D, Corning, Corning, NY, USA), an ultrasonic bath (5510R-DTH, Branson, St. Louis, MO, USA), a homogenizer (YOM300D, Yotec, Taiwan), and an ultrasonic liquid processor (Q700, Qsonica, Newton, CT, USA). The aforementioned dispersion method was repeated three times to keep superior stability for the CBNFs based on our past research experience [30,[33][34][35]. Next, 1.0 wt% CBNF with 1.6 wt% GA was further diluted with water to a final concentration of 0.05 wt% and 0.2 wt% CBNFs, and the ratio of GA to CBNMs in each CBNFs was fixed at 8:5.…”