Numerical Analysis of Heat Transfer in Unsteady Nanofluids in a Small Pipe with Pulse Pressure
Abstract
In the present paper, developing turbulence forced convection flows were numerically investigated by using water-Al2O3 nano-fluid through a circular compact pipe which has 4.5mm diameter. Each model has a steady state and uniform heat flux (UHF) at the wall. The whole numerical experiments were processed under the RPM 100 to 500 and the nano-fluid models were made by the Alumina volume fraction. Single-phase fluid models were defined through nano-fluid physical and thermal properties calculations, Two-phase models (mixture granular model) were processed in 100nm diameter. The results show that comparison of nusselt number and heat transfer rate are improved as the Al2O3 volume fraction increased. All of the numerical flow simulations are processed by the FLUENT. The results show an increase from volume fraction concentration and an increase in heat transfer coefficient with increasing RPM.
Keywords
Download Options
Introduction
Heat transfer fluids play an important role in many industries, including power plants; production processes, transportation and electronics, and the heat transfer characteristics of thermal fluids play an important role in the development of energy efficient heat transfer devices. Past improvements have been based on structural changes and the addition of heat transfer areas, vibrations on the surface of the heat, injection or inhalation of fluids and the application of electrons or magnetic fields. These enhancement techniques rarely meet the increase in heat transfer coefficient and, in this connection; there is a strong demand for the development of advanced heat transfer fluids with higher heat transfer properties. Therefore, a number of recent studies on nanofluids for experimental convective heat transfer through circular tubes have been conducted by senior scholars. However, nanofluid research is still in the hot debate and investigation. In addition, research on the pulse pressure has been actively carried out all over the world, and many research results have been published especially in the field of noise vibration. Non-steady pulsating flow phenomena will be generated by internal smoke and reciprocating compressors. The pulsating pressure in the internal combustion engine will be the silencer part. The function of this silencer is to reduce the pulsation pressure inside the silencer as well as to reduce the back pressure.
Maxwell [1,2] has demonstrated that increasing the volume fraction of solid particles can increase the thermal conductivity of the mixture. The particle diameter currently available for particle manufacturing technology development is smaller than 100 nm, called nano-size. This effort allows the particle mixing fluid to increase the thermal conductivity of the heat transfer fluid by increasing the critical thermal conductivity. In addition, solid nanoparticle colloids are very stable and do not exhibit significant sedimentation under static conditions after weeks or months. In addition, solid colloids float easily when you reduce particle size. Therefore, nanofluidic technology is expected to be suitable for heat transfer fluids.
Conclusion
Numerical analysis of the heat transfer of the nanofluid in the unsteady state in the small tube into which the pulsating pressure is introduced showed that the effect of the content of Al2O3, which is a nanofluid, was further increased in the low 100 RPM. In addition, it was confirmed that the nanofluids of 0% and 1% compared to 0% and 1% of Al 2 O 3 have a data difference of more than 2 times. In 500 RPM, the difference in content is not significant compared to 100 RPM, but nanofluids with high Al 2 O 3 The heat transfer coefficient and the number of nuns were better. And the increase in the heat transfer coefficient of the nanofluid to the RPM change shows better results as the RPM increases. Therefore, nanofluid with high Al2O3 content and high RPM can improve the thermoelectric coefficient and increase the number of nuts. But the CFD should be progressed with constant and transient numerical investigation parallel. Basically, It would be pace with the experiment especially different model scale study. Also, uniform heat flux sample, wall shear stress, body force researches does not include this paper. This compact size model is not usual model on the nano-fluid CFD study so these factors need to be proved.