Energy Transport Mechanisms in Nanofluids and Its Applications

2009 ◽  
Author(s):  
Yimin Xuan ◽  
Qiang Li
Keyword(s):  
Heat Transfer ◽  
Energy Transport ◽  
Transfer Mechanism ◽  
Thermal Engineering ◽  
Energy Transfer Mechanism ◽  
Transport Mechanisms ◽  
Thermal Systems ◽  
Flow And Heat Transfer ◽  
Solid Liquid ◽  
Suspended Nanoparticles

Nanofluid is a solid-liquid mixture consisting of solid nanoparticles or nanofibers with sizes typically of 1–100 nm suspended in liquid. Thermal conductivity and heat transfer performance of nanofluids is superior to those of the original pure carrier fluids because the suspended nanoparticles remarkably improve energy exchange capability of the suspensions. In the present paper, the investigations efforts cover microscopic and mesoscaled approachs for the heat transfer enhancement mechanism of the nanofluid, flow and heat transfer mechanism and the relevant control methods of the magnetic fluid by suspending magnetic nanoparticles in base fluids, and some applications of nanofluid on a variety of thermal systems in order to understand energy transfer mechanism of nanofluids and guide future applications of nanofluids to thermal engineering.

Large Eddy Simulation of Flow and Heat Transfer Mechanism in Matrix Cooling Channel

2017 ◽  
Author(s):  
Yigang Luan ◽  
Lianfeng Yang ◽  
Bo Wan ◽  
Tao Sun
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Large Eddy Simulation ◽  
Gas Turbine ◽  
Transfer Mechanism ◽  
Heat Transfer Mechanism ◽  
Longitudinal Vortices ◽  
Eddy Simulation ◽  
Flow And Heat Transfer ◽  
Large Eddy

Gas turbine engines have been widely used in modern industry especially in the aviation, marine and energy fields. The efficiency of gas turbines directly affects the economy and emissions. It’s acknowledged that the higher turbine inlet temperatures contribute to the overall gas turbine engine efficiency. Since the components are subject to the heat load, the internal cooling technology of turbine blades is of vital importance to ensure the safe and normal operation. This paper is focused on exploring the flow and heat transfer mechanism in matrix cooling channels. In order to analyze the internal flow field characteristics of this cooling configuration at a Reynolds number of 30000 accurately, large eddy simulation method is carried out. Methods of vortex identification and field synergy are employed to study its flow field. Cross-sectional views of velocity in three subchannels at different positions have been presented. The results show that the airflow is strongly disturbed by the bending part. It’s concluded that due to the bending structure, the airflow becomes complex and disordered. When the airflow goes from the inlet to the turning, some small-sized and discontinuous vortices are formed. Behind the bending structure, the size of the vortices becomes big and the vortices fill the subchannels. Because of the structure of latticework, the airflow is affected by each other. Airflow in one subchannel can exert a shear force on another airflow in the opposite subchannel. It’s the force whose direction is the same as the vortex that enhances the longitudinal vortices. And the longitudinal vortices contribute to the energy exchange of the internal airflow and the heat transfer between airflow and walls. Besides, a comparison of the CFD results and the experimental data is made to prove that the numerical simulation methods are reasonable and acceptable.

Improved Heat Transfer Using Micro-Structures in Trifold Solar Energy Conversion Systems

2014 ◽  
Vol 659 ◽  
pp. 417-420
Author(s):  
Aristotel Popescu ◽  
David Pfund ◽  
Abel Hernandez-Guerrero ◽  
Ema Carmen Panaite ◽  
Ana Georgiana Lupu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Solar Energy ◽  
Energy Conversion ◽  
Renewable Energy Sources ◽  
Solar Energy Conversion ◽  
Thermal Systems ◽  
Heat Transfer Augmentation ◽  
Flow And Heat Transfer ◽  
Energy Conversion Systems ◽  
Micro Structures

The worldwide renewable energy sources harvesting grew recently at rates of 10–60% annually for many technologies, due to improvements made in all areas. In solar energy conversion, an improvement recently presented in literature is the hybrid system that provides both electricity and thermal energy for domestic applications. For the trifold PV-TE-DHW system, the electrical conversion efficiency is increased by using a thermoelectric (TE) module. This paper proposes the use of micro-channeled heat exchangers at both hot and cold sides of the TE module to improve the heat exchange from the working fluids. The authors developed prior works and published papers in the area of fluid flow and heat transfer in microstructures, heat transfer augmentation, and in solar thermal systems. Results obtained show an improved efficiency energy transfer.

scholarly journals A Spatially Advancing Turbulent Flow and Heat Transfer in a Curved Channel(Thermal Engineering)

2009 ◽  
Vol 75 (754) ◽  
pp. 1336-1343 ◽  
Author(s):  
Koji MATSUBARA ◽  
Akihiko MATSUI ◽  
Takahiro MIURA ◽  
Atsushi SAKURAI ◽  
Hitoshi SUTO ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Thermal Engineering ◽  
Curved Channel ◽  
Flow And Heat Transfer

Flow and Heat Transfer Enhancement of Nanofluids in Microchannel With Blocks and Grooves

2013 ◽  
Author(s):  
Ping Li ◽  
Jianhui Chen ◽  
Huancheng Qu ◽  
Yonghui Xie ◽  
Di Zhang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Heat Transfer Enhancement ◽  
Energy Transport ◽  
Recirculation Zone ◽  
Volume Concentration ◽  
Flow Analysis ◽  
Transfer Enhancement ◽  
Flow And Heat Transfer

A code based on the lattice-Boltzmann method was programmed. At various Reynolds numbers, simulations of the Cu/water nanofluid flow structure and heat transfer performance in a two dimensional microchannel with blocks (Re = 10–100) and grooves (Re = 50–200) were conducted, and the factors affecting the flow and heat transfer were explored. The flow and heat transfer of nanofluids with nanoparticle volume concentration of 0.5%, 1.0%, 1.5% and 2.0% were simulated, obtaining the velocity and temperature distributions to compare with the results of base fluid. Flow analysis showed that recirculation zones formed behind the blocks and in the grooves when nanofluids flowed in the microchannel, and the size of recirculation zone increased with the increase of Reynolds number and nanoparticle volume concentration. The core of the recirculation zone in the groove gradually moved to the right wall as Reynolds number increased at the same nanoparticle volume concentration, and the direction of the main flow was getting horizontal. Heat transfer results indicated that the addition of nanoparticles could promote fluid flow and energy transport, so that the thermal boundary layer thickness decreased and the heat transfer was enhanced. The heat transfer enhancement increased with the increase of Reynolds number and nanoparticle volume concentration. It was also shown that the heat transfer enhancement by increasing the Reynolds number was limited. The results could give a fundamental understanding for designing highly efficient heat exchangers.

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