Thermal and electrical property measurements for coal

Dindi, Hasan; X, Bai; Krantz, William B.

doi:10.1016/0016-2361(89)90321-9

Cited by 20 publications

(15 citation statements)

References 3 publications

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“…To date, electrical conductivity has been measured in coals and coal char, but solely for the purpose of correlating in situ conductivity measurements to fuel processing as part of underground coal gasification programs. 28,29 In this work, we present a method for solution processing sub-100 nm natural carbon particles from standard coal sources to obtain 100 nm thick coal films and characterize their microstructure by scanning electron microscopy (SEM). We relate the carbon bonding configuration (characterized with Raman spectroscopy) to the conductivity, optical absorption properties, and the dominant charge transport mechanism, through variable temperature (50 K to room temperature) current−voltage measurements.…”

Section: * S Supporting Informationmentioning

confidence: 99%

Rethinking Coal: Thin Films of Solution Processed Natural Carbon Nanoparticles for Electronic Devices

2016

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Disordered carbon materials, both amorphous and with long-range order, have been used in a variety of applications, from conductive additives and contact materials to transistors and photovoltaics. Here we show a flexible solution-based method of preparing thin films with tunable electrical properties from suspensions of ball-milled coals following centrifugation. The as-prepared films retain the rich carbon chemistry of the starting coals with conductivities ranging over orders of magnitude, and thermal treatment of the resulting films further tunes the electrical conductivity in excess of 7 orders of magnitude. Optical absorption measurements demonstrate tunable optical gaps from 0 to 1.8 eV. Through low-temperature conductivity measurements and Raman spectroscopy, we demonstrate that variable range hopping controls the electrical properties in as-prepared and thermally treated films and that annealing increases the sp 2 content, localization length, and disorder. The measured hopping energies demonstrate electronic properties similar to amorphous carbon materials and reduced graphene oxide. Finally, Joule heating devices were fabricated from coal-based films, and temperatures as high as 285°C with excellent stability were achieved. KEYWORDS: Coal, amorphous carbon, organic semiconductors, thin films, solution processing C arbon has long been known as one of the most chemically versatile elements. As a result, carbonaceous materials have been of technological interest for their wide range of electronic propertiesresulting in materials ranging from low cost conducting materials such as graphite and carbon black, to semiconducting fullerenes and carbon nanotubes, and to insulating diamond and diamond-like carbon. Specifically, carbon black, carbon filaments, and other carbon materials are used in electrodes, conductivity additives, and electromagnetic reflectors. 1 Graphitic materials 2 and amorphous carbon (a-C) 3,4 are the leading and a promising candidate, respectively, for anode materials in lithium ion batteries. Amorphous carbon has also been used in the manufacturing of transistors 5,6 and photovoltaic devices, 7,8 and nanostructured graphitic materials (such as graphene and reduced graphene oxide) have gained significant attention for applications including in photovoltaics, 9−11 transparent conductive membranes, 12−16 and Joule heating devices. 17−19 Despite decades of research on synthetically processed carbon materials, facile, tunable, 20 low-temperature, solution processing methods remain elusive. Carbon black synthesis requires temperatures as high as 2000°C, 21 and a-C is typically deposited by plasma-enhanced chemical vapor deposition (CVD) 22,23 although aerosol-assisted CVD has recently been demonstrated. 8 While extensive research has been conducted to develop solution-based methods of graphene deposition, rGO films remain several orders of magnitude less conductive than CVD graphene. 16,24,25 In contrast to the widely studied world of synthetic carbonaceous materials, the optical...

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Section: * S Supporting Informationmentioning

confidence: 99%

Rethinking Coal: Thin Films of Solution Processed Natural Carbon Nanoparticles for Electronic Devices

2016

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“…This discrepancy may be associated with differences in the measurement techniques and sample preparation procedures as well as the moisture content in the solid fuels tested. Dindi et al [8] determined the thermal conductivity of wet and dry coal samples using the transient hot wire and hot plate methods. The authors observed that at ambient temperature the thermal conductivity decreased from 0.4 to 0.2 W/(m K) as a result of drying.…”

Section: Effect Of Compositionmentioning

confidence: 99%

“…For example, Badzioch et al [7] measured the thermal conductivity of 12 types of coal by the hot wire method from the room temperature to 900 o C. The authors observed that the thermal conductivity increased with increasing temperature for all tested coals. Dindi et al [8] also measured the thermal conductivity of coal by the hot wire method at temperatures up to 420 o C. Furthermore, Singer et al [9] demonstrated a variation in conductivity data gathered by the hot plate method at test temperatures up to 800 o C. Stanger et al [13] determined the thermal conductivity of maceral concentrates from a coal using the numerical computer aided thermal analysis technique. Figure 6 shows the effect of temperature on the thermal conductivity of the solid fuels determined by various techniques.…”

Section: Effect Of Temperaturementioning

confidence: 99%

“…Early experimental work was primarily performed using the steady-state, guarded hot plate method (e.g., Clendenin et al [6]). Thereafter, transient techniques, such as the hot wire method (Badzioch et al [7], Dindi et al [8]), hot plate method (Dindi et al [8]), heat flow meter method (Singer and Tye [9], Herrin and Deming [10]), plane source method (Suleiman et al [11]), optical scanning method (Popov et al [12]), and numerical CATA (computer aided thermal analysis) technique (Stanger et al [13]) were developed. Measurements of the thermal conductivity of solid fuels are often associated with those of specific heat and are included in the reviews of Clendenin et al [6], Badzioch et al [7], Agroskin et al [14], Eisermann et al [15] and Strezov et al [16].…”

Section: Introductionmentioning

confidence: 99%

“…They observed that the measured thermal conductivities were higher in the parallel direction. Dindi et al [8] determined the thermal conductivity of coal samples in which the heat flow was oriented parallel and nonparallel to the bedding planes using the transient hot wire and hot plate methods. The authors observed that the thermal conductivities measured with the heat conduction parallel to the bedding planes were approximately 25 to 30% greater than those in the nonparallel configuration.…”

Section: Introductionmentioning

confidence: 99%

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Determination of the effective thermal conductivity of solid fuels by the laser flash method

Kosowska-Golachowska¹,

Gajewski²,

Musiał³

2014

Archives of Thermodynamics

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In this study, a new laser flash system was proposed for the determination of the thermal conductivity of brown coal, hard coal and anthracite. The main objective of the investigation was to determine the effect of coal rank, composition, physical structure and temperature on thermal conductivity. The solid fuels tested were medium conductors of heat whose determined thermal conductivities were in the range of 0.09 to 0.23 W/(m K) at room temperature. The thermal conductivity of the solid fuels tested typically increased with the rank of coal and the measurement temperature. The results of this study show that the physical structure of solid fuels and temperature have a dominant effect on the fuels' thermal conductivity.Keywords: Effective thermal conductivity; Effective thermal diffusivity; Specific heat; Laser flash method; Hard coal; Brown coal; Anthracite-fixed carbon content, wt% h -thickness, m HHV -higher heating value -calorific value, MJ/kg M -moisture content, wt%

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Measurement of electrical resistivity of coal samples

Tiwary

Mukhdeo

1993

Fuel

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Thermal and electrical property measurements for coal

Cited by 20 publications

References 3 publications

Rethinking Coal: Thin Films of Solution Processed Natural Carbon Nanoparticles for Electronic Devices

Rethinking Coal: Thin Films of Solution Processed Natural Carbon Nanoparticles for Electronic Devices

Determination of the effective thermal conductivity of solid fuels by the laser flash method

Measurement of electrical resistivity of coal samples

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