scholarly journals The influence of gold nanoparticles on the thermal conductivity of water solutions of graphen

2019 ◽  
pp. 14-20
Author(s):  
V.V. Korskanov ◽  
O.M. Fesenko ◽  
T.V. Tsebrienko ◽  
O.P. Budnik ◽  
V.B. Dolgoshey
Keyword(s):  
Thermal Conductivity ◽  
Gold Nanoparticles ◽  
Effective Thermal Conductivity ◽  
Au Nanoparticles ◽  
Water Solution ◽  
Significant Difference ◽  
Temperature Dependences ◽  
Different Temperatures ◽  
Graphene Nanoparticles ◽  
Degree Of Purification

The objects of study were water dispersions of raw graphene (hereinafter referred to as graphene-n), higher degree of purification of graphene samples (hereinafter graphene), and nanoparticles of graphene-Au nanoparticles based on them. The thermal conductivity of water graphene dispersions and water dispersions of gold graphene nanoparticles nanostructures at different temperatures and component ratios was investigated. The values ​​of effective thermal conductivity of dry nanofillers are calculated. The temperature dependences of the thermal conductivity of the nanofillers were obtained. It is found that the in-thermal conductivity of water dispersions of purified graphene is higher than the thermal conductivity of raw graphene as a result of better packing of nanoparticles in pure graphene nanofillers compared to raw. The effect of enhancement of thermal conductivity of gold nanoparticles, which is accompanied by higher absolute values of thermal conductivity of nanoparticles of graphene-nanoparticles of gold than the corresponding graphene, was revealed. At the same time, there is a significant difference in thermal conductivity between nanoparticles of graphene nanoparticles of gold. It is established that higher values of thermal conductivity of graphene-nanoparticles nanostructures of gold are the result of the reinforcing action of a gold nanoparticle substrate, which is formed as a result of joint sedimentation with graphene during the formation of nano-flakes from water solution during evaporation of water.

Thermal Conductivities of Porous Rocks Filled with Stagnant Fluid

1961 ◽  
Vol 1 (01) ◽  
pp. 37-42 ◽  
Author(s):  
D. Kunii ◽  
J.M. Smith
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Water Solution ◽  
Pure Water ◽  
General System ◽  
Practical Significance ◽  
Glycerol Water ◽  
Starting Point ◽  
Thermal Conductivities ◽  
Stagnant Fluid

Abstract Effective thermal conductivities of sandstones filled with stagnant fluids were measured using a steady-state technique. Data were obtained for seven sandstone samples, taken from four different locations and ranging in permeability from 18 to 590 md. The measurements with gases (helium, nitrogen, air and carbon dioxide) covered a pressure range from 0.039 psia to 400 psig. Data were taken for four liquids - n-heptane, methyl alcohol, 79.8 weight per cent glycerol-water solution and pure water at atmospheric pressure. The experimental results were used to evaluate the theoretical equations for predicting stagnant conductivities developed earlier. The low-pressure measurements permitted evaluation of the consolidation parameter hpDp/ks (necessary to utilize the theory) for the various types of sandstones. Using these characteristic values, the theoretical equations correlated well with the experimental conductivity data for the several fluids and rock samples. Introduction An aspect of heat transfer in solid-fluid systems of considerable current interest is the effective thermal conductivity of porous media. The stimulus for study of the subject arises from the need for sound procedures for designing thermal methods of petroleum production. The general system occurs when there exists a flow of fluid through the pores of the solid material. However, a logical starting point in developing a theory for predicting the effective thermal conductivity in the general system is to attack the special case when the porous solid is filled with stagnant fluid. Since the flow rates anticipated in thermal production processes are very low, such stagnant conductivities k are also of practical significance.

The Effective Thermal Conductivity of Porous Polymethacrylimide Foams

2014 ◽  
Vol 609-610 ◽  
pp. 196-200 ◽  
Author(s):  
Peng Yue ◽  
Lin Qiu ◽  
Xing Hua Zheng ◽  
Da Wei Tang
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Formation Mechanism ◽  
3Ω Method ◽  
Temperature Range ◽  
Different Temperatures ◽  
The Relationship

A freestanding sensor-based 3ω method was employed to measure the effective thermal conductivity of porous polymethacrylimide (PMI) foams with different densities at different temperatures. Experimental data showed that within the measuring temperature range, the effective thermal conductivity increased with temperature. Moreover, the formation mechanism of the relationship between the effective thermal conductivity and temperature was analyzed in this paper.

scholarly journals Study on the Thermal Conductivity of Mannitol Enhanced by Graphene Nanoparticles for Thermoelectric Power Generation

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Jia Yu ◽  
Haoqing Wang ◽  
Li Kong ◽  
Hongji Zhu ◽  
Qingshan Zhu
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Open Circuit ◽  
Stable Operation ◽  
Test Results ◽  
Temperature Environment ◽  
Large Heat ◽  
Composite Phase Change Material ◽  
Graphene Nanoparticles ◽  
Change Material

The existing thermoelectric materials are greatly affected by the temperature environment, which can provide better power output in a stable temperature environment by using composite phase change material with enhanced heat conduction. The graphene is dispersed in the liquid mannitol to make the nanomixed material. Test results show that the thermal conductivity of mannitol increased from 0.7 Wm-1 K-1 to 2.07 Wm-1 K-1, 179.73% times as much. The effective thermal conductivity of mannitol can be increased to 8.4236 Wm-1 K-1 by using a graphite foam with a porosity of 0.9. After adding 1 wt.% and 5 wt.% graphene particles, the effective thermal conductivity increased to 8.73 Wm-1 K-1 and 9.63 Wm-1 K-1, respectively. The simulation results in a large heat source environment show that mannitol with improved thermal conductivity can ensure the stable operation of the thermoelectric material in the optimal temperature environment for 120 s, and the open-circuit voltage is maintained at about 6.5 V in that time.

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