The diffusivity modeling of different gases in acrylonitrile butadiene styrene (ABS)

In this work, we used three gases (CO2, N2 and normal hexane) for diffusivity measurements in Acrylonitrile butadiene styrene (ABS). We proposed a diffusion model that the diffusion coefficients of each gas in ABS could be estimated from the specific volume of ABS/gas mixture and chemical potential of gas in ABS. The solubility and diffusivity of three gases into ABS were determined by a magnetic suspension balance. The results showed that the solubility and diffusivity of three gases increased with increasing of pressure. Also it was determined that N2 has a lowest solubility and the highest diffusivity in ABS in all temperature and pressure ranges. It was shown that there was a suitable overlapping between the experimental and predicted values from the proposed model, in which the proposed model could successfully estimate the diffusion coefficient of mentioned gases in ABS in all temperature and pressure ranges.

UJI KETAHANAN KOROSI TEMPERATUR TINGGI (700OC) DARI LOGAM PADUAN Fe-Cr- Y2O3 SEBAGAI BAHAN ALTERNATIF KELONGSONG (CLADDING) BAHAN BAKAR NUKLIR

Salah satu pemenuhan energi listrik saat ini yang terus meningkat. Pembangkit Listrik Tenaga Nuklir (PLTN) merupakan salah satu sumber energi listrik yang cukup efisien dibandingkan dengan sumber energi listrik lainnya. PLTN memerlukan suatu pengamanan yang lebih, salah satunya adalah pengamanan kelongsong (cladding) bahan bakar nuklir. Penelitian tentang kelongsong ( cladding ) telah diuji ketahanan logam paduan Fe-Cr-Y2O3 sebagai kelongsong bahan bakar terhadap korosi pada temperatur 700OC selama 6 jam, pemanasan pada suhu tinggi, dengan variasi suhu yaitu 500ºC, 600ºC dan 700ºC . Hasil uji korosi mengunakan Magnetic Suspension Balance (MSB) menunjukkan bahwa Paduan Fe-Cr-Y2O3 mempunyai ketahanan korosi lebih besar dibandingkan dengan serbuk yang tidak ditambahkan Y2O3. Mikrostruktur permukaan logam Fe-Cr-Y2O3 yang terkorosi dikarakterisasi dengan menggunakan Scanning Electron Microscope (SEM) dan X-Ray Difractometer (XRD).

A New Technique for Simultaneous Measurement of Nanodarcy-Range Permeability and Adsorption Isotherms of Tight Rocks Using Magnetic Suspension Balance

Summary Flow and adsorptive characteristics of methane and other natural gases onto tight rock formations are of economic interest for proper engineering evaluation and reservoir performance management. This work presents a novel technique to enable the simultaneous determination of nanodarcy permeability and adsorption isotherms of gas in such formations through the transient analysis of experimental data from magnetic suspension balance (MSB). MSB has primarily been shown to be an effective tool for evaluating the amount of gases adsorbed onto tight shales/coals, especially when the adsorbed amount is small. In addition to the classical usage of the measured data using MSB, a new mathematical model based on volume averaging has been developed to describe the transient behavior of the adsorption phenomenon and to obtain the nominal or apparent permeability of shale samples from experimental data. Historically, the permeability of nanoporous materials is measured using two leading methods: the Gas Research Institute method and the pressure–pulse–decay method; however, neither of these methods yields information about the adsorptive behavior of the porous medium or considers such phenomena. In this study, we developed a simple theoretical framework to obtain the isotherm of gas adsorption onto a tight shale (or other tight materials such as coal) sample and the permeability of the sample, simultaneously. The results show that the permeability vs. pressure plot follows the Klinkenberg effect at lower pressures, as expected. The overall methodology developed here can be applied to any type of adsorbing gases and shale/coal samples. The utility and validity of the methodology are demonstrated by applying the developed methodology in experiments performed on three tight shale samples (unconventionals) using two different gases: methane and CO2.

Pore structure characteristics and methane adsorption and desorption properties of marine shale in Sichuan Province, China

Isothermal adsorption and desorption experiments were carried out using gravimetric method with magnetic suspension balance.