• Energy Research

Abstract Reticulated porous ceramics (RPCs) have promising potentials as substrates in catalytic reactions where higher surface area is favorable. In this paper, we investigate the CO2 conversion efficiency of calcium and aluminum doped lanthanum manganite – LCMA (La0.6Ca0.4Mn0.6Al0.4O3±δ) perovskite. The LCMA perovskite coats the surface of an RPC to maximize available reactive surface in reduction-oxidation (redox) reactions. We provide a robust approach in synthesis and characterization of the LCMA, RPC and the coating process through x-ray micro computed tomography (XCT), x-ray diffraction (XRD) and scanning electron microscopy (SEM) imaging. Our results show the presence of a dual pore size distribution in the RPC with the larger pores forming a connected network and smaller ones within struts. We show that the LCMA coated RPC is capable of converting CO2 to carbon monoxide ([CO%] = 3.2) when exposed to 10 vol% CO2 feed gas (at 1050 °C) after ~1.5 h of reduction reaction at 1240 °C. The XCT characterization shows that the redox conditions affect the RPC in two ways: i. distortion of the RPC structure and the removal of smaller pores. ii. the LCMA layer migration into the RPC framework resulting in the reduction of the specific surface area between coating and porous network.

Abstract Reticulated porous ceramics (RPCs) have promising potentials as substrates in catalytic reactions where higher surface area is favorable. In this paper, we investigate the CO2 conversion efficiency of calcium and aluminum doped lanthanum manganite – LCMA (La0.6Ca0.4Mn0.6Al0.4O3±δ) perovskite. The LCMA perovskite coats the surface of an RPC to maximize available reactive surface in reduction-oxidation (redox) reactions. We provide a robust approach in synthesis and characterization of the LCMA, RPC and the coating process through x-ray micro computed tomography (XCT), x-ray diffraction (XRD) and scanning electron microscopy (SEM) imaging. Our results show the presence of a dual pore size distribution in the RPC with the larger pores forming a connected network and smaller ones within struts. We show that the LCMA coated RPC is capable of converting CO2 to carbon monoxide ([CO%] = 3.2) when exposed to 10 vol% CO2 feed gas (at 1050 °C) after ~1.5 h of reduction reaction at 1240 °C. The XCT characterization shows that the redox conditions affect the RPC in two ways: i. distortion of the RPC structure and the removal of smaller pores. ii. the LCMA layer migration into the RPC framework resulting in the reduction of the specific surface area between coating and porous network.

The low-velocity impact response of closed-cell aluminium foams using various shaped indenters has been investigated. Impact tests were conducted using an instrumented drop-tower with flat, hemispherical, conical and truncated-conical indenter at impact energies ranging from 46.8 J to 105 J. The effects of variation of indenter shape and impact velocity on mechanical properties and deformation mechanisms of foam have been explicitly investigated. The results show that the mechanical response of closed-cell aluminium foams under low-velocity projectile impact significantly depends on the indenters' nose shape and initial impact energy. The deformation mechanisms of foam for different shaped indenters have been elucidated using reconstructed X-ray micro-computed tomography (XCT) images of the indented specimens. A good correlation between the indenter shape and deformation mechanisms has been observed. The structure-property relations of foams during dynamic indentation have also been explored by analysing the XCT images of the indented specimens. The parameters that influence the energy absorption capacity of the material are also presented.

The low-velocity impact response of closed-cell aluminium foams using various shaped indenters has been investigated. Impact tests were conducted using an instrumented drop-tower with flat, hemispherical, conical and truncated-conical indenter at impact energies ranging from 46.8 J to 105 J. The effects of variation of indenter shape and impact velocity on mechanical properties and deformation mechanisms of foam have been explicitly investigated. The results show that the mechanical response of closed-cell aluminium foams under low-velocity projectile impact significantly depends on the indenters' nose shape and initial impact energy. The deformation mechanisms of foam for different shaped indenters have been elucidated using reconstructed X-ray micro-computed tomography (XCT) images of the indented specimens. A good correlation between the indenter shape and deformation mechanisms has been observed. The structure-property relations of foams during dynamic indentation have also been explored by analysing the XCT images of the indented specimens. The parameters that influence the energy absorption capacity of the material are also presented.

Abstract We describe an imaging and pore-scale modelling study of capillary trapping in the Paaratte Sandstone formation in the Otway Basin, Australia. Three-dimensional X-ray computed tomography (micro-CT) was used to characterize the pore structure of the reservoir core. We obtain in-situ pore-scale images of the distribution of CO2:brine analogue fluid pairs (octane:brine) within reservoir samples during low capillary number drainage and imbibition flooding experiments. The images were recorded using time-lapse X-ray micro-tomography at elevated pressure. The observed two-phase fluid distributions are consistent with a water wet system. The micro-CT images are used directly as input to a geometrically accurate quasi-static pore-scale simulation model. The validity of the quasi-static assumption is investigated by comparing on a pore-by-pore basis the simulated and imaged fluid distributions. The pore filling states are in good agreement both for drainage and imbibition displacements and the computed capillary trapping curve agrees with experimental data. This indicate that quasi-static pore-scale physics can be used to obtain averaged or continuum flow properties for low capillary number displacements. We perform a sensitivity study of the impact of the advancing contact angle on capillary trapping. The magnitude of residual trapping increases with decreasing contact angle. Land's trapping coefficient increases with increasing contact angle. We compute capillary pressure and relative permeability scanning curves. Simulated relative permeability hysteresis is compared with that predicted by the industry-standard Carlson's and Killough's models. Killough's model reproduces the simulated data more accurately.

Abstract We describe an imaging and pore-scale modelling study of capillary trapping in the Paaratte Sandstone formation in the Otway Basin, Australia. Three-dimensional X-ray computed tomography (micro-CT) was used to characterize the pore structure of the reservoir core. We obtain in-situ pore-scale images of the distribution of CO2:brine analogue fluid pairs (octane:brine) within reservoir samples during low capillary number drainage and imbibition flooding experiments. The images were recorded using time-lapse X-ray micro-tomography at elevated pressure. The observed two-phase fluid distributions are consistent with a water wet system. The micro-CT images are used directly as input to a geometrically accurate quasi-static pore-scale simulation model. The validity of the quasi-static assumption is investigated by comparing on a pore-by-pore basis the simulated and imaged fluid distributions. The pore filling states are in good agreement both for drainage and imbibition displacements and the computed capillary trapping curve agrees with experimental data. This indicate that quasi-static pore-scale physics can be used to obtain averaged or continuum flow properties for low capillary number displacements. We perform a sensitivity study of the impact of the advancing contact angle on capillary trapping. The magnitude of residual trapping increases with decreasing contact angle. Land's trapping coefficient increases with increasing contact angle. We compute capillary pressure and relative permeability scanning curves. Simulated relative permeability hysteresis is compared with that predicted by the industry-standard Carlson's and Killough's models. Killough's model reproduces the simulated data more accurately.