A Study of Thermal Effectiveness of Laminar Forced Convection of Nanofluids

2012 ◽  
Author(s):  
Leyuan Yu ◽  
Dong Liu
Keyword(s):  
Forced Convection ◽  
Base Fluid ◽  
Theoretical Studies ◽  
Constant Flow ◽  
Pumping Power ◽  
Constant Flow Rate ◽  
Figures Of Merit ◽  
Convective Thermal ◽  
Laminar Forced Convection ◽  
Flow Constraints

Recent theoretical studies show that the convective thermal performance of nanofluids in cooling applications depends crucially on the effective thermophysical properties and, if the performance comparisons are made under different flow constraints, contradictory conclusions can be drawn regarding the effectiveness of the same nanofluid. In this work, an experimental study was reported on the laminar forced convection of Al2O3-water and Al2O3-Polyalphaolefin (PAO) nanofluids through a circular minichannel. Based on the experimental data, the thermal effectivenesses of the nanofluids were evaluated critically using various figures of merit (FOM) under three typical flow constraints, i.e., constant flow rate, constant Reynolds number and constant pumping power. Although the nanofluids enhance convective heat transfer, the results show their overall thermal effectiveness is adversely affected by the combined effects of higher viscosity and lower specific heat. In particular, when the cooling application is constrained by the constant pumping power condition, there is virtually no difference in the thermal performances between the base fluid and the nanofluids.

scholarly journals Forced Convection of Al2O3–Cu, TiO2–SiO2, FWCNT–Fe3O4, and ND–Fe3O4 Hybrid Nanofluid in Porous Media

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2902 ◽  
Author(s):  
M. Z. Saghir ◽  
M. M. Rahman
Keyword(s):  
Porous Media ◽  
Ethylene Glycol ◽  
Forced Convection ◽  
Numerical Code ◽  
Hybrid Nanofluid ◽  
Pumping Power ◽  
Cooling Process ◽  
Constant Flow Rate ◽  
New Class ◽  
Hybrid Fluid

Adding nanoparticles to fluid has led to a new class of fluids named as nanofluids. Different concentrations and its effective cooling have attracted many engineering applications to test this new fluid. Lately, important heat enhancement has been observed by dispersing two distinct nanoparticles in the regular fluid. This type of hybrid nanofluid has led researchers to study its effectiveness in the cooling process. Here, we experimentally studied the forced convection of Al2O3–Cu hybrid nanofluid in porous media at a constant flow rate and heating condition. The numerical code after being calibrated with the experimental results is used to predict the effectiveness in cooling by using a set of hybrid fluid of TiO2–SiO2, MWCNT–Fe3O4, and ND–Fe3O4 at different concentrations. In the experiment, we used water and a water–ethylene glycol mixture as base fluids. The results revealed that the hybrid fluid contributed to heat enhancement levied increased pumping power. However, the index of efficiency, obtained by combining the Nusselt number and pressure drop, indicated that the best hybrid fluid for such an application is ND–Fe3O4 in the water–ethylene glycol mixture.

STUDY OF LAMINAR FORCED CONVECTION FOR DIFFERENT CONCENTRATIONS OF THE WATER-LITHIUM BROMIDE MIXTURE

2018 ◽  
Author(s):  
Allan Giuseppe ◽  
dhiego veloso ◽  
Carlos Antonio Cabral Santos ◽  
Pedro Gonçalves ◽  
Fábio Lima
Keyword(s):  
Forced Convection ◽  
Lithium Bromide ◽  
Laminar Forced Convection

An anti-settling sample delivery instrument for serial femtosecond crystallography

2012 ◽  
Vol 45 (4) ◽  
pp. 674-678 ◽  
Author(s):  
Lukas Lomb ◽  
Jan Steinbrener ◽  
Sadia Bari ◽  
Daniel Beisel ◽  
Daniel Berndt ◽  
...  
Keyword(s):  
Constant Flow ◽  
Syringe Pump ◽  
Experimental Conditions ◽  
Flow Rates ◽  
X Ray ◽  
Constant Flow Rate ◽  
Significant Impairment ◽  
Working Principle ◽  
After Hours ◽  
Serial Femtosecond Crystallography

Serial femtosecond crystallography (SFX) using X-ray free-electron laser (FEL) sources has the potential to determine the structures of macromolecules beyond the limitation of radiation damage and without the need for crystals of sufficient size for conventional crystallography. In SFX, a liquid microjet is used to inject randomly oriented crystals suspended in their storage solution into the FEL beam. Settling of crystals in the reservoir prior to the injection has been found to complicate the data collection. This article details the development of an anti-settling sample delivery instrument based on a rotating syringe pump, capable of producing flow rates and liquid pressures necessary for the operation of the injector. The device has been used successfully with crystals of different proteins, with crystal sizes smaller than 20 µm. Even after hours of continuous operation, no significant impairment of the experiments due to sample settling was observed. This article describes the working principle of the instrument and sets it in context with regard to the experimental conditions used for SFX. Hit rates for longer measuring periods are compared with and without the instrument operating. Two versions of the instrument have been developed, which both deliver sample at a constant flow rate but which differ in their minimum liquid flow rates and maximum pressures.

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