Ultra-High Temperature Thermal Conductivity Measurements of a Reactive Magnesium Manganese Oxide Porous Bed Using a Transient Hot Wire Method

2021 ◽  
Author(s):  
Michael Hayes ◽  
Faezeh Masooomi ◽  
Philipp Schimmels ◽  
Kelvin Randhir ◽  
James Klausner ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Manganese Oxide ◽  
Effective Thermal Conductivity ◽  
Phonon Transport ◽  
Experimental Results ◽  
Transient Hot Wire ◽  
Hot Wire ◽  
Transient Hot Wire Method ◽  
Proposed Model ◽  
Wire Method

Abstract The effective thermal conductivity of packed beds of magnesium-manganese oxide pellets is a crucial parameter for engineering Magnesium Manganese Oxide (Mg-Mn-O) thermochemical energy storage devices. We have measured the effective thermal conductivity of a packed bed of 3.66 ±0.516 mm sized magnesium manganese oxide (Mn to Mg molar ratio of 1:1) pellets in the temperature range of 300 to 1400°C. Since the material is electrically conductive at temperatures above 600°C, the sheathed transient hot wire method is used for measurements. Raw data is analyzed using the Blackwell solution to extract the bed thermal conductivity. The effective thermal conductivity standard deviation is less than 10% for a minimum of three repeat measurements at each temperature. Experimental results show an increase in the effective thermal conductivity with temperature from 0.50 W/m °C around 300°C to 1.81 W/m °C close to 1400°C. We propose a dual porosity model to express the effective thermal conductivity as a function of temperature. This model also considers the effect of radiation within the bed, as this is the dominant heat transfer mode at high temperatures. The proposed model accounts for micro-scale pellet porosity, macro-scale bed porosity, pellet size, solid thermal conductivity (phonon transport), and radiation (photon transport). The coefficient of determination between the proposed model and the experimental results is greater than 0.90.

Thermal Conductivity Affected by Temperature and Particle Size in Al2O3-Water Nanofluids

2011 ◽  
Author(s):  
D. Kwek ◽  
A. Crivoi ◽  
Fei Duan
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Effective Thermal Conductivity ◽  
Experimental Results ◽  
Al2o3 Nanoparticles ◽  
Particle Sizes ◽  
Transient Hot Wire ◽  
Hot Wire ◽  
Nanoparticle Concentration ◽  
Wire Method

The effective thermal conductivity of Al2O3-water nanofluids has been measured using a transient hot wire method. Experimental results demonstrate that the thermal conductivity of Al2O3 nanofluids increases linearly with increasing nanoparticle concentration. Adding 5 vol % of Al2O3 nanoparticles in water increases the effective thermal conductivity of the nanofluids by 20%. Thermal conductivity of Al2O3 nanofluids increases with an increase of temperature. The enhancement is around 1.7% at 15 °C in comparison with around 16% at 55 °C in a 1 vol % nanofluid. The particle size is another important parameter for the effective thermal conductivity. The increase of thermal conductivity reduces from 30% to 10% as the particle sizes increase from 10 nm to 35 nm. The increase of the effective thermal conductivity starts as the particle size increases above 35 nm, reaching about 27.5% in the nanofluid with the particle size at 150 nm.

Investigation on Thermal Conductivity of Low Concentration AlN/EG Nanofluids

2013 ◽  
Vol 546 ◽  
pp. 112-116
Author(s):  
Yan Jiao Li ◽  
Chang Jiang Liu ◽  
Zhi Qing Guo ◽  
Qiu Juan Lv ◽  
Fang Xie
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Volume Fraction ◽  
Maxwell Model ◽  
Experimental Results ◽  
Effect Of Temperature ◽  
Transient Hot Wire ◽  
Hot Wire ◽  
Wire Method ◽  
Nanoparticles Volume Fraction

The thermal conductivity of AlN/EG nanofluids was investigated by transient hot-wire method. Experimental results indicated that the thermal conductivity of AlN/EG nanofluids increase nearly linear with the increase of nanoparticles volume fraction, and the results can’t be predicted by conditional Maxwell model. The effect of temperature on effective thermal conductivity of AlN/EG nanofluids was investigated. Result indicated that the thermal conductivity of AlN/EG nanofluids increased with the increase of temperature.

Transient and Steady-State Experimental Comparison Study of Effective Thermal Conductivity of Al2O3∕Water Nanofluids

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Calvin H. Li ◽  
Wesley Williams ◽  
Jacopo Buongiorno ◽  
Lin-Wen Hu ◽  
G. P. Peterson
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Steady State ◽  
Effective Thermal Conductivity ◽  
Room Temperature ◽  
Transient Hot Wire ◽  
Hot Wire ◽  
Transient Hot Wire Method ◽  
Wire Method ◽  
Reported Data

Nanofluids are being studied for their potential to enhance heat transfer, which could have a significant impact on energy generation and storage systems. However, only limited experimental data on metal and metal-oxide based nanofluids, showing enhancement of the thermal conductivity, are currently available. Moreover, the majority of the data currently available have been obtained using transient methods. Some controversy exists as to the validity of the measured enhancement and the possibility that this enhancement may be an artifact of the experimental methodology. In the current investigation, Al2O3∕water nanofluids with normal diameters of 47nm at different volume fractions (0.5%, 2%, 4%, and 6%) have been investigated, using two different methodologies: a transient hot-wire method and a steady-state cut-bar method. The comparison of the measured data obtained using these two different experimental systems at room temperature was conducted and the experimental data at higher temperatures were obtained with steady-state cut-bar method and compared with previously reported data obtained using a transient hot-wire method. The arguments that the methodology is the cause of the observed enhancement of nanofluids effective thermal conductivity are evaluated and resolved. It is clear from the results that at room temperature, both the steady-state cut-bar and transient hot-wire methods result in nearly identical values for the effective thermal conductivity of the nanofluids tested, while at higher temperatures, the onset of natural convection results in larger measured effective thermal conductivities for the hot-wire method than those obtained using the steady-state cut-bar method. The experimental data at room temperature were also compared with previously reported data at room temperature and current available theoretical models, and the deviations of experimental data from the predicted values are presented and discussed.

Measuring Thermal Conductivity of Fluids Containing Oxide Nanoparticles

1999 ◽  
Vol 121 (2) ◽  
pp. 280-289 ◽  
Author(s):  
S. Lee ◽  
S. U.-S. Choi ◽  
S. Li ◽  
J. A. Eastman
Keyword(s):  
Thermal Conductivity ◽  
Particle Shape ◽  
Experimental Results ◽  
Oxide Nanoparticles ◽  
Transient Hot Wire ◽  
Hot Wire ◽  
Transient Hot Wire Method ◽  
Wire Method ◽  
Al2o3 Particles ◽  
Thermal Conductivities

Oxide nanofluids were produced and their thermal conductivities were measured by a transient hot-wire method. The experimental results show that these nanofluids, containing a small amount of nanoparticles, have substantially higher thermal conductivities than the same liquids without nanoparticles. Comparisons between experiments and the Hamilton and Crosser model show that the model can predict the thermal conductivity of nanofluids containing large agglomerated Al2O3 particles. However, the model appears to be inadequate for nanofluids containing CuO particles. This suggests that not only particle shape but size is considered to be dominant in enhancing the thermal conductivity of nanofluids.

Effect of Volume Fraction and Temperature on Thermal Conductivity of SiO2 Nanofluids

2011 ◽  
Vol 306-307 ◽  
pp. 1178-1181 ◽  
Author(s):  
Bao Jie Zhu ◽  
Wei Lin Zhao ◽  
Dong Dong Li ◽  
Jin Kai Li
Keyword(s):  
Thermal Conductivity ◽  
Ethylene Glycol ◽  
Volume Fraction ◽  
Experimental Results ◽  
Transient Hot Wire ◽  
Hot Wire ◽  
Transient Hot Wire Method ◽  
Wire Method ◽  
Thermal Conductivities

Thermal conductivities of two kinds of nanofluids (SiO2-water and SiO2-ethylene glycol) were measured by transient hot-wire method at different volume fraction and temperature. Influences of volume fraction of particles and temperature on thermal conductivities of nanofluids were analyzed. The Experimental results show that thermal conductivities of nanofluids are higher than those of base fluids, and increase with the increase of volume fraction and temperature. When approximately 0.5% volume fraction of SiO2nanoparticles are added into water and ethylene glycol at the temperature 50°C, the thermal conductivities are enhanced 46.2% and 62.8% respectively.

Analysis of the Transient Hot-Wire Method to Measure Thermal Conductivity of Silica Aerogel: Influence of Wire Length, and Radiation Properties

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Ellann Cohen ◽  
Leon Glicksman
Keyword(s):  
Thermal Conductivity ◽  
Silica Aerogel ◽  
Test Method ◽  
Wire Radius ◽  
Wire Length ◽  
Transient Hot Wire ◽  
Hot Wire ◽  
End Effects ◽  
Transient Hot Wire Method ◽  
Wire Method

When the transient hot-wire method is used to measure the thermal conductivity of very low thermal conductivity silica aerogel (in the range of 10 mW/m·K at 1 atm) end effects due to the finite wire size and radiation corrections must be considered. An approximate method is presented to account for end effects with realistic boundary conditions. The method was applied to small experimental samples of the aerogel using different wire lengths. Initial conductivity results varied with wire length. This variation was eliminated by the use of the end effect correction. The test method was validated with the NIST (National Institute of Standards and Technology) Standard Reference Material 1459, fumed silica board to within 1 mW/m·K. The aerogel is semitransparent. Due to the small wire radius and short transient, radiation heat transfer may not be fully accounted for. In a full size aerogel panel radiation will augment the phonon conduction by a larger amount.

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