Anisotropic thermal conductivity and permeability of compacted expanded natural graphite

Abstract

Solidified expanded natural graphite (ENG) has good heat and mass transfer characteristics and has recently been utilized as a matrix for heat and mass transfer performance intensification in adsorption refrigeration and air conditioning equipment. In order to gain an overall understanding of the heat and mass transfer process in solidified expanded natural graphite, the anisotropic thermal conductivities and permeabilities are investigated in two types of solidified block, i.e. discs of solidified expanded natural graphite (DSENG) and plates of solidified expanded natural graphite (PSENG), in which the heat conductive and mass transfer directions are parallel and perpendicular, respectively, to the pressing direction producing blocks. An unexpected phenomenon is found in the research, which is that the thermal conductivity sometimes decreases while the density of the solidified ENG increases, this only occurring for the heat conductive direction perpendicular to the pressing direction. Results also show that the direction has larger thermal conductivity also has a better permeability; the phenomena of anisotropic thermal conductivities are strongly dependent on density. The reasons are analyzed in the paper, and they are mainly related with the distribution of micro layers inside the samples.

A novel drying process for oil adsorption of expanded graphite

“…Furthermore, the EG had a loose and porous vermicular structure. The structure of the EG appeared to have parallel boards and it exhibited many pores with different sizes [10,11]. Fig.…”

Thermal-physical properties of the carbon-carbon materials on base of graphite foam

“…изкоплотные материалы на основе термо-расширенного графита обладают рядом важных технических качеств: высокими хими-ческой и термической стойкостью (выдержи-вают нагрев до 3000 °С в инертной атмосфере) и пористостью, простотой формования, позво-ляющей получать компакты с широким варьи-руемым интервалом теплопроводности [1][2][3], что определяет возможность их применения в различных сферах производства как в качестве высокотемпературной изоляции, так и в каче-стве теплораспределителя. В частности, такие материалы нашли применение в производстве теплораспределяющих панелей для потолочных систем обогрева и кондиционирования помеще-ний [4,5].…”

“…При этом измеряли нагрузку на образец и смещение каретки разрывной машины. По тангенсам угла наклона начальных линейных участков полу-ченных кривых сжатия рассчитывали модуль Юнга: (2) где E -модуль упругости, МПа; F -приложен-ная сила, Н; l -высота образца, мм; S -пло-щадь основания образца, мм 2 ; х -деформация образца, мм.…”

Development of thermal conductive consolidated activated carbon for adsorption refrigeration

“…The bulk density of granular AC of 80-100 mesh is 369 kg m -3 , and the bulk density Fig.2 Relation between bulk density of AC, percentage of AC, and density of composite adsorbents 3 Study on the thermal conductivity 3.1 Thermal conductivity of composite adsorbents Thermal conductivity was measured by an Anter Quickline-10 using the ASTM E1530 guarded thermal flow meter method [15]. Before the thermal conductivity of composite adsorbents was tested, the calibration experiments were preceded.…”

“…Considering the anisotropic thermal conductivity and permeability of consolidated expanded graphite matrix [15], the plate samples, for which the thermal conductive and mass transferring direction is perpendicular with the compressing direction (Fig.1a), were developed for the experiments.…”