Experimental measurement of dynamic concentration of nanofluid in laminar flow

Abstract

Nanofluid is thought to have a potential enhancement in heat transfer behaviour of fluid. The nanoparticle concentration in nanofluid is one of the most important factors that affect the nanofluid behaviour. The static concentration was applied in the researches under flowing condition. In this paper, Nuclear Magnetic Resonance (NMR) scanning was applied to study the dynamic concentration of nanofluid flow in pipe. The experiments were carried out with ferrofluid under different concentration and temperature. A new parameter T2 * was introduced in the study. Experiments were carried out to obtain the T2 * of nanofluid in the pipe. An empirical equation based on T2 * and temperature was proposed to calculate the concentration of nanoparticles. Then, experiments were carried out with flowing ferrofluid in pipe. The dynamic concentration was calculated with the empirical equation. It has a highest concentration near the pipe wall. The concentration decreases from the wall to the pipe centre.Furthermore, the experiment result also gives out a chance to investigate the mechanism of nanoparticle movement in laminar flow with the concentration gradient along radius.

Effect of rotating twisted tape on thermo-hydraulic performances of nanofluids in heat-exchanger systems

“…Hong et al [12] investigated the dynamic concentration of nanofluids in laminar low and proposed an empirical equation to calculate the concentration of nanoparticles in a pipe. It was found that the concentration of nanofluids decreases from the wall to centre in the pipe and it has a maximum value near the pipe wall.…”