scholarly journals On Heat Transfer Performance of Cooling Systems Using Nanofluid for Electric Motor Applications

Entropy ◽  
2020 ◽  
Vol 22 (1) ◽  
pp. 99 ◽  
Author(s):  
Ali Deriszadeh ◽  
Filippo de Monte
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Base Fluid ◽  
Heat Transfer Performance ◽  
Volume Fraction ◽  
Cooling System ◽  
Transfer Performance ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer

This paper studies the fluid flow and heat transfer characteristics of nanofluids as advance coolants for the cooling system of electric motors. Investigations are carried out using numerical analysis for a cooling system with spiral channels. To solve the governing equations, computational fluid dynamics and 3D fluid motion analysis are used. The base fluid is water with a laminar flow. The fluid Reynolds number and turn-number of spiral channels are evaluation parameters. The effect of nanoparticles volume fraction in the base fluid on the heat transfer performance of the cooling system is studied. Increasing the volume fraction of nanoparticles leads to improving the heat transfer performance of the cooling system. On the other hand, a high-volume fraction of the nanofluid increases the pressure drop of the coolant fluid and increases the required pumping power. This paper aims at finding a trade-off between effective parameters by studying both fluid flow and heat transfer characteristics of the nanofluid.

scholarly journals Numerical study on the flow and heat transfer of water-based Al2O3 forced pulsating nanofluids based on self-excited oscillation chamber structure

2021 ◽  
pp. 167-167
Author(s):  
Hong Yuan ◽  
Zhao Wang ◽  
Quan Gao ◽  
Ting Fu
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Local Nusselt Number ◽  
Performance Index ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Excited Oscillation

In this study, the flow and heat transfer characteristics of the forced pulsating Al2O3/water nanofluid were numerically studied. The pulsating excitation of the nanofluid is provided by the Helmhertz self-excited oscillating cavity. The large eddy simulation method is used to solve the equation, and the local Nusselt number and heat transfer performance index are used to analyze the heat transfer characteristics of the nanofluid in the self-excited oscillation heat exchange tube. In addition, the effect of different downstream tube diameters on heat transfer enhancement is discussed. The research results show that the existence of the countercurrent vortex can increase the disturbance of the near-wall fluid, thereby improving the mixing degree of the near-wall fluid and the central mainstream. As the countercurrent vortex migrates downstream, pulse enhanced heat transfer is realized. Furthermore, it was also found that when the downstream tube diameter d2=1.8d1, the periodic effect of the local Nusselt number of the wall is the best and the heat transfer performance index has the most stable pulsation effect within a pulsation cycle. But when d2=2.0d1, the change curve of heat transfer performance index in a pulsating period is the highest, the maximum value is 3.95.

Effect of droplet characteristics and rotation speed on the flow and heat transfer characteristics of mist/air cooling in a rotating ribbed two-pass rectangular channel

2016 ◽  
Vol 231 (2) ◽  
pp. 119-132 ◽  
Author(s):  
Xinjun Wang ◽  
Feng Zhang ◽  
Daren Zheng ◽  
Jun Li
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Heat Transfer Performance ◽  
Rotation Speed ◽  
Rectangular Channel ◽  
Air Cooling ◽  
Transfer Performance ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer

The flow and heat transfer characteristics of mist/air cooling in the rotating ribbed two-pass rectangular channel are numerically investigated using the CFD software ANSYS-CFX. In this article, a comparison in heat transfer performance between the mist/air cooling and the air-only cooling is performed. Additionally, the effect of the initial mist diameter, temperature, velocity and the channel rotation speed on the mist/air cooling performance is analysed. The results show that the droplet flow distance and Nusselt number of the mist/air cooling increase as the initial mist temperature decreases. In addition, as the initial mist diameter decreases, the diameter of mist on the whole channel decreases, resulting in the higher heat transfer, whilst the mist concentration also decreases, leading to the lower heat transfer. Therefore, there is an optimal initial mist diameter which makes the heat transfer performance best. Nevertheless, the droplet movement and heat transfer performance of mist/air cooling are nearly insensitive to the initial mist velocity. It is also noted that the Coriolis force increases with the channel rotation speed, causing the flow deflection becomes more obvious. Consequently, as the channel rotation speed increases, in the first passage the averaged Nusselt number on the trailing wall increases, and that on the leading wall decreases, while the trend in the second passage is reversed.

Research on External Flow and Heat Transfer Characteristics of H-Type Fin Tube Based on Longitudinal Vortex

2014 ◽  
Vol 614 ◽  
pp. 133-137 ◽  
Author(s):  
Bo Jiang ◽  
Wei Dong Hao ◽  
Zhi Hong Hu ◽  
Fu Guo Liu
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Heat Transfer Performance ◽  
External Flow ◽  
Longitudinal Vortex ◽  
Transfer Performance ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Fin Tube

An H-type fin tube based on longitudinal vortex for boiler economizer is put forward in this paper, in order to solve the problem of too high temperature for denitration catalyst reaction for flue gas leaving the econonmizer. CFD method is adopted to study the external flow and heat transfer characteristics of the H-type fin tube based on longitudinal vortex, obtaining the flow field and temperature field distribution in the near wall region outside the fin tube. The results show that vortex flow in different degrees occurs in the rear flow field of the H-type fin tube based on longitudinal vortex, which introduces velocity component normal to main stream direction to the fluid of main flow zone, improves the synergy of temperature gradient field with velocity field and significantly enhances heat transfer performance of the fin tube. Within the parameter range studied in this paper, the 30° attack angle makes the best PEC value and correspondingly best comprehensive heat transfer performance.

scholarly journals Conduction and convection heat transfer characteristics of water-based au nanofluids in a square cavity with differentially heated side walls subjected to constant temperatures

2014 ◽  
Vol 18 (suppl.1) ◽  
pp. 189-200 ◽  
Author(s):  
Primoz Ternik ◽  
Rebeka Rudolf
Keyword(s):  
Heat Transfer ◽  
Rayleigh Number ◽  
Base Fluid ◽  
Volume Fraction ◽  
Heat Transfer Characteristics ◽  
Square Cavity ◽  
Onset Of Convection ◽  
Transfer Characteristics ◽  
Wide Range ◽  
Water Based

The present work deals with the natural convection in a square cavity filled with the water-based Au nanofluid. The cavity is heated on the vertical and cooled from the adjacent wall, while the other two horizontal walls are adiabatic. The governing differential equations have been solved by the standard finite volume method and the hydrodynamic and thermal fields were coupled together using the Boussinesq approximation. The main objective of this study is to investigate the influence of the nanoparticles? volume fraction on the heat transfer characteristics of Au nanofluids at the given base fluid?s (i.e. water) Rayleigh number. Accurate results are presented over a wide range of the base fluid Rayleigh number and the volume fraction of Au nanoparticles. It is shown that adding nanoparticles in a base fluid delays the onset of convection. Contrary to what is argued by many authors, we show by numerical simulations that the use of nanofluids can reduce the heat transfer rate instead of increasing it.

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