scholarly journals Thermal Conductivity of Detonation Nanodiamond Hydrogels and Hydrosols by Direct Heat Flux Measurements

Gels ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 248
Author(s):  
Liliya O. Usoltseva ◽  
Dmitry S. Volkov ◽  
Evgeny A. Karpushkin ◽  
Mikhail V. Korobov ◽  
Mikhail A. Proskurnin
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Standard Deviation ◽  
Heat Flow ◽  
Detonation Nanodiamond ◽  
Conductivity Measurements ◽  
Maximum Increase ◽  
Relative Standard ◽  
Flux Measurements ◽  
Heat Flow Meter

The methodology and results of thermal conductivity measurements by the heat-flow technique for the detonation nanodiamond suspension gels, sols, and powders of several brands in the range of nanoparticle concentrations of 2–100% w/w are discussed. The conditions of assessing the thermal conductivity of the fluids and gels (a FOX 50 heat-flow meter) with the reproducibility (relative standard deviation) of 1% are proposed. The maximum increase of 13% was recorded for the nanodiamond gels (140 mg mL−1 or 4% v/v) of the RDDM brand, at 0.687 ± 0.005 W m−1 K−1. The thermal conductivity of the nanodiamond powders is estimated as 0.26 ± 0.03 and 0.35 ± 0.04 W m−1 K−1 for the RUDDM and RDDM brands, respectively. The thermal conductivity for the aqueous pastes containing 26% v/v RUDDM is 0.85 ± 0.04 W m−1 K−1. The dignities, shortcomings, and limitations of this approach are discussed and compared with the determining of the thermal conductivity with photothermal-lens spectrometry.

Apparatus to Measure Thermal Conductivity in Filled Rubber Stocks

1969 ◽  
Vol 42 (5) ◽  
pp. 1314-1320 ◽  
Author(s):  
J. H. Atkins ◽  
J. E. Sullivan
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Standard Deviation ◽  
Temperature Drop ◽  
Sample Thickness ◽  
Filled Rubber ◽  
Three Samples ◽  
Additional Equipment ◽  
Relative Standard ◽  
Flux Probe

Abstract An instrument to measure thermal conductivity of cured rubber stocks is described. The apparatus can be used with readily available equipment or additional equipment may be purchased. The results obtained are as accurate and precise as those obtained using other instruments and can be done at a rate of three samples per hour. The apparatus is designed around a calibrated heat flux probe which measures the sample's heat flux. The heat flux, the temperature drop across the sample, and the sample thickness values permit conversion of the above data into a thermal conductivity value. Thirteen samples of Butyl rubber in a curing bladder formulation with 40-part loadings of various carbon blacks were prepared and tested. The thermal conductivity values obtained varied from 0.096 to 0.117 (Btu)/(ft2) (hr)(°F/ft) over a range of 95° F to 212° F with an overall relative standard deviation of 1.2%. The thermal conductivity of the above samples were also measured on a modified apparatus over a temperature range of 95° F to 350° F and there was no change in the thermal conductivity values. To check the above measurements, five of the samples were tested on two commercial instruments. The results agreed within 4 per cent. For reasons explained in the paper, we believe our results to be the most accurate.

scholarly journals The Influence of Different Facings of Polyisocyanurate Boards on Heat Transfer through the Wall Corners of Insulated Buildings

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1991 ◽  
Author(s):  
Tomas Makaveckas ◽  
Raimondas Bliūdžius ◽  
Arūnas Burlingis
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Flux ◽  
Thermal Insulation ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Thermal Bridge ◽  
Thermal Bridges ◽  
The Impact ◽  
Heat Flow Meter

Polyisocyanurate (PIR) thermal insulation boards faced with carboard, plastic, aluminum, or multilayer facings are used for thermal insulation of buildings. Facing materials are selected according to the conditions of use of PIR products. At the corners of the building where these products are joined, facings can be in the direction of the heat flux movement and significantly increase heat transfer through the linear thermal bridge formed in the connection of PIR boards with facing of both walls. Analyzing the installation of PIR thermal insulation products on the walls of a building, the structural schemes of linear thermal bridges were created, numerical calculations of the heat transfer coefficients of the linear thermal bridges were performed, and the influence of various facings on the heat transfer through the thermal bridge was evaluated. Furthermore, an experimental measurement using a heat flow meter apparatus was performed in order to confirm the results obtained by numerical calculation. This study provides more understanding concerning the necessity to evaluate the impact of different thermal conductivity facings on the heat transfer through corners of buildings insulated with PIR boards.

Evaluation of Infrared Absorption on Thermal Properties of Modified Modacrylic Fibers

2020 ◽  
Vol 7 (2) ◽  
pp. 27-34
Author(s):  
Hannah Alexis Rich ◽  
Amor M. Camatcho ◽  
Hannah Jean Stephenson ◽  
Jacob Crew ◽  
Jesse S. Jur ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Thermal Properties ◽  
Infrared Absorption ◽  
Infrared Radiation ◽  
Imaging Camera ◽  
Flux Measurements ◽  
Thermal Signature ◽  
Changes Over Time ◽  
Over Time

A novel modacrylic fiber with the capability to absorb ∼80% of all infrared radiation was evaluated for use in personal thermal comfort applications. Using an infrared (IR) imaging camera to monitor optical changes over time and heat flux measurements, it was concluded that this altered modacrylic fiber possesses both a unique thermal signature as well as increased heat flux compared to 100% cotton. A design of experiments (DOE) was conducted to determine if blending this material with other fibers would result in a fabric with a higher thermal conductivity. It was observed that blends of nylon and the altered modacrylic tended to have the highest conductivity and would provide a cooling effect if used in a garment.

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