Water Nanofluid Heat Transfer Research Articles

Experimental investigation of Silver / Water nanofluid heat transfer in car radiator

Currently available fluids for heat transfer including refrigerants, water, ethylene glycol mixture, etc., have been widely exploited in various fields, especially in automobile cooling systems, for many years. However, these fluids possess poor heat transfer capability which means that to achieve acceptable heat transfer activity, high compactness and effectiveness of heat transfer systems are essential. This research work concentrates on preparation and use of water based Silver containing nanofluids in automobile cooling system. Nanoparticles volume fraction, fluid inlet temperature, coolant and air Reynolds numbers were optimized so that the heat transfer performance of the car radiator system was totally improved. It was found that increasing these parameters leads to enhancement of the heat transfer performance. In the best condition, the Ag/water nanofluids with low concentrations could amend heat transfer efficiency up to 30.2% in comparison to pure water.

Al2O3–Water nanofluid heat transfer and entropy generation in a ribbed channel with wavy wall in the presence of magnetic field

In this article, a parametric study is conducted to evaluate heat transfer enhancement in a ribbed channel containing Al2O3–Water nanofluid with wavy wall. The physical domain is under the influence of the magnetic field that creates a negative force against the working fluid to move. Nanofluid with higher temperature enters the cool ribbed duct and heat is exchanged along the walls of channel. The effects of the dominant parameters including number of the blocks, solid volume fractions of nanofluid, Hartmann number, Reynolds number, and different states of amplitude sine waves are numerically tested on the local and average Nusselt number, skin friction, and total entropy generation. Excellent agreement between present study and previous literature is observed. It is found that, an augmentation in magnetic field will result in higher values of both local and average Nusselt number accompanying with bigger values of skin friction and entropy generation. Computations illustrate that, increasing the solid volume fraction of the Al2O3 nanoparticles will raise the Nusselt number and total entropy generation rate but its effect on the skin friction is negligible. Also, numerical results imply that increasing amplitude sine waves of the geometry has incremental effect on the Nusselt number and skin friction but its effect on the total entropy generation rate is not so clear. Moreover, by adding number of the used blocks in the presence of magnetic field, the local Nusselt number experiences more jumps but it does not increase the average Nusselt number, necessarily. In addition, using more blocks increases skin friction but it has a reverse effect on the total entropy generation rate.

Nanofluid heat transfer in a permeable enclosure in presence of variable magnetic field by means of CVFEM

This research is about modeling the influence of Lorentz forces on Fe3O4–water nanofluid heat transfer enhancement in a permeable cavity. Shape factor influence on thermal conductivity of nanofluid is taken into consideration. Vorticity stream function formulation is utilized. The solutions of final equations are obtained by Control Volume based Finite Element Method. Graphs are shown for different values of radiation parameter (Rd), Darcy number (Da), nanofluid volume fraction (ϕ), Rayleigh number (Ra) and Hartmann number (Ha). Results indicate that heat transfer rate enhances with augment of Hartmann number. Selecting Platelet shaped nanoparticles leads to greatest heat transfer rate.

Experimental study of Cu–water nanofluid heat transfer and pressure drop in a horizontal double-tube heat exchanger

This article reports an experimental study on the performance of horizontal double tube counter-flow heat exchanger. Due to the modicum in the heat transfer surface area, the overall heat transfer coefficient is enhanced. Cu-nanoparticles are added to the cold water in the annulus of the heat exchanger, however, the inner tube that contains the hot water is rotated. The inner tube is made of copper with 25.4mm outer diameter with a thickness of 2mm, while the outer tube, which is made of transparent Acrylic Plexiglass, has an outer diameter of 76.2mm and 5mm thickness. Cu–water nanofluid is prepared at volume fractions of 1–3% and the inner tube is rotated with speed from 0 to 500rpm. Results demonstrated a remarkable enhancement in the rate of heat transfer due to the nanoparticles addition as well as the inner tube rotation. Consequently, the effectiveness and the transfer number units (NTU) of the heat exchanger are augmented. Optimization between heat transfer augmentation and the pressure drop penalty is carried out. Finally, the use of the nanofluid has a little penalty in pressure drop in compared with the inner tube rotation.

Effect of magnetic field on Cu–water nanofluid heat transfer using GMDH-type neural network

Heat transfer of Cu–water nanofluid over a stretching cylinder in the presence of magnetic field has been investigated. The group method of data handling (GMDH) type neural networks (NNs) is used to calculate Nusselt number formulation. Results indicate that GMDH-type NN in comparison with fourth-order Runge–Kutta integration scheme provides an effective means of efficiently recognizing the patterns in data and accurately predicting a performance. The effects of nanoparticle volume fraction, magnetic parameter and Reynolds number on Nusselt number are studied by sensitivity analyses. The results show that Nusselt number is an increasing function of Reynolds number and volume fraction of nanoparticles while it is a decreasing function of magnetic parameter. As volume fraction of nanoparticles increases, the effect of this parameter on Nusselt number also increases, but opposite behavior is obtained for magnetic parameter and Reynolds number.

Laminar convective heat transfer and viscous pressure loss of alumina–water and zirconia–water nanofluids

Laminar convective heat transfer and viscous pressure loss were investigated for alumina–water and zirconia–water nanofluids in a flow loop with a vertical heated tube. The heat transfer coefficients in the entrance region and in the fully developed region are found to increase by 17% and 27%, respectively, for alumina–water nanofluid at 6 vol % with respect to pure water. The zirconia–water nanofluid heat transfer coefficient increases by approximately 2% in the entrance region and 3% in the fully developed region at 1.32 vol %. The measured pressure loss for the nanofluids is in general much higher than for pure water. However, both the measured nanofluid heat transfer coefficient and pressure loss are in good agreement with the traditional model predictions for laminar flow, provided that the loading- and temperature-dependent thermophysical properties of the nanofluids are utilized in the evaluation of the dimensionless numbers. In other words, no abnormal heat transfer enhancement or pressure loss was observed within measurement errors.