The Experimental Study In The Dispersion Stability And Convective Heat Transfer Of Nanofluids In Laminar Flow

Responding to the need device miniaturization and more efficient heat transfer system researchers have been devoted many efforts to heat enhancement techniques. However, traditional methods such as expending surface are difficult to meet the special conditions of heat transfer and cooling requirements. In recent years, the rapid growth of nanotechnology provides new opportunities for enhancement of heat transfer. The experimental investigations have revealed that the nanofluids have remarkably higher thermal conductivities than those of conventional pure fluids and that the nanofluids have great potential for heat transfer enhancement. It is shows thar nanofluids have broad application prospects and potential economic value.The purpose of this paper is to demonstrate experimentally and theoretically the feasibility of the concept of nanofluids. This research includes of preparation and stability of nanofluids and characterization the heat transfer behavior of nanofluids are indicated from the following aspects.1. Preparation of nanofluids and the suspension stability analysisTiO₂ nanoparticle suspension has been prepared by mixing nanoparticles and base fluids. The auxiliary dispersants of SDBS and ultrasonic oscillation were necessary to obtain stabilized suspensions. Sedimentation experiment, granularity test were given to illustrate the stability of nanofluids2. The stability of particle suspensions flowing in laminar pipe with elbowSolid particles are susceptible to the centrifugal force and subsidence occurred and even abrasion the pipeline within the two-phase flow in pipe fluid flow. Apparently, it is very important to reduce particle reunion, deposition to obtain stable suspensions of nano-fluid. The main content of this article is to study the suspension of nanofluids flowing in laminar flow. The methods characterizing dispersion stability is to use the diversification of particle concentration of nanofluids. Transmission electron microscopy (TEM) and particle size analyzer were used to observe the particle diameter size and morphology.3. The effect of particle concentration on stability of suspension in laminar flow range Currently, the dispersion of nanofluids flowing in elbow tube is rarely reported in the literature. It has been found that the particle suspension can not keep a stable state, we must consider the factor of dispersion stability when relating the convective heat transfer experiments.4. Experimental study of convective heat characteristics of nanofluidsAn experimental system was designed to investigate convective heat transfer characteristics of TiO₂ flowing in a tube. The results show that adding nanoparticles in liquid can significantly increase the coefficient of convective heat transfer. The mass fraction of particle is a main factor that affects its effect on convective heat transfer, while not increased in proportion with particle mass fraction.Studies have shown that adding nanoparticles in liquid can significantly increase the thermal conductivity, to enhance heat transfer performance of heat change systems. Therefore, nanofluids have broad application prospects and potential economic value. Now, researchers are paid more attention on the heat transfer enhancement of nanofluids. This article provides experimental basis that how to get stability nanofluids in a dynamic situation and some guidance used in scientific research and industrial practice.