Research on the Technology of Recovering Low Concentration Ni+ Metal Ion Solution

Under environmentally friendly and environmental issues, wastewater treatment in laboratories and factories is an important international issue. Among them, wastewater from the chemical industry accounts for a large part of industrial wastewater discharge. The introduction of new technologies to treat chemical wastewater is of great significance. In particular, the amount of wastewater produced by inorganic chemistry experiments is relatively large, and the pollutants are mostly heavy metal salts. According to the characteristics of inorganic chemistry experimental wastewater, such as special nature, small amount, strong discontinuity, high hazard, complex and changeable composition, etc., design a chemical reaction to provide a practical and feasible method to treat wastewater with high efficiency and low cost. This research initially takes Ni+ metal ion waste liquid as the first stage of recycling and treatment to improve the traditional low-concentration non-economic treatment. The preliminary results of this research are neutralization reaction and optimal pH value control of Ni+ waste liquid to generate Ni+ precursors to increase the economic value of recycling will be the basis for providing in-house recycling systems for electroplating plants, panel plants, and semiconductor plants to achieve emission reduction, green chemical industry and green environmental protection.

Change in the amplitude of strong discontinuity wave propagating in a rod made of Murnaghan material

The paper presents calculations of the change in amplitude of strong discontinuity wave propagating in a thin rod made of hyperelastic Murnaghan material. Two functions were assumed for the calculations, describing the change of the cross-section of the rod with the constant scaling parameter?for both decreasing cross-sections of the analysed steel rods. A numerical analysis was performed based on analytical solutions. The analytical form of solution for both rods with decreasing cross-sections allowed for preparation of contour maps for the propagating wave of strong discontinuity. Furthermore, the changes in the relative amplitude of the propagating shock wave in a thin rod were determined for two rods analysed in the study, for which the differences in the values of the relative amplitude in the final cross-section were found.

Topographical effect of the Antarctic Peninsula on a strong wind event

The topographical effect on a strong wind event that occurred on 7 January 2013 at King Sejong Station (KSJ), Antarctica, was investigated using the Polar Weather Research and Forecasting (WRF) model. Numerical experiments applying three different terrain heights of the Antarctic Peninsula (AP) were performed to quantitatively estimate the topographical effect on the selected strong wind event. The experiment employing original AP topography successfully represented the observed features in the strong wind event, both in terms of peak wind speed (by ~94%; ~19.7 m/s) and abrupt transitions of wind speed. In contrast, the experiment with a flattened terrain height significantly underestimated the peak wind speeds (by ~51%; ~10.4 m/s) of the observations. An absence of AP topography failed to simulate both a strong discontinuity of sea-level pressure fields around the east coast of the AP and a strong south-easterly wind over the AP. As a result, the observed downslope windstorm, driven by a flow overriding a barrier, was not formed at the western side of the AP, resulting in no further enhancement of the wind at KSJ. This result demonstrates that the topography of the AP played a critical role in driving the strong wind event at KSJ on 7 January 2013, accounting for ~50% of the total wind speed.

A 3D Coupled Thermal-Hydraulic-Mechanical THM Model Using EDFM and XFEM for Hydraulic-Fracture-Dominated Geothermal Reservoirs

Enhanced Geothermal Systems (EGS) are those geothermal reservoirs artificially fractured to create paths for injected low-temperature fluid which is then heated up along the flow path until production for electricity generation. This heat recovery involves three tightly coupled processes: thermal, hydraulic and mechanical which interacts with each other and in turn affects the energy production. The local temperature field would be disturbed by injected fuild, resulting in thermal/poroelastic responses near the hydraulic fractured area which are the dominant factors of fluid flow. In this paper, the three-dimensional (3D) Embedded Discrete Fracture Model (EDFM) was adopted to describe the geometry of the fracture and simulate fluid flow and heat transfer between fractures and the matrix, while mechanics, including displacement of the strong discontinuity (fractures), was solved by the 3D eXtended Finite Element Method (XFEM). With the capability of modeling fractures of arbitrary shapes within a 3D reservoir domain using 3D EDFM-XFEM, a coupled THM model was developed based on the unconditionally stable fixed-stress split sequential-implicit method, where the fluid flow/heat transfer module and mechanics module are solved iteratively until convergence within a time step. Fluid flow/heat transfer and XFEM with internal/external tractions are both validated by comparison with existing simulators. We conducted simulations for two synthetic geothermal reservoir heat recovery cases to investigate the effects of the injection temperature and boundary traction condition on the production temperature and fracture deformation. The results indicate that the fracture aperture and permeability is sensitive to temperature variation and hence impacts the production rate/temperature. Thermal strain might be the dominant factor of rock deformation, especially in the shallow depth where geostress is at a low level.

General Consistency of Strong Discontinuity Kinematics in Embedded Finite Element Method (E-FEM) Formulations

This paper performs an in-depth study of the theoretical basis behind the strong discontinuity methods to improve local fracture simulations using the Embedded Finite Element Method (E-FEM). The process starts from a review of the elemental enhancement functions found in current E-FEM literature, providing the reader a solid context of E-FEM fundamentals. A set of theoretical pathologies is then discussed, which prevent current frameworks from attaining full kinematic consistency and introduce unintended mesh dependencies. Based on this analysis, a new proposal of strong discontinuity enhancement functions is presented considering generalised fracture kinematics in a full tridimensional setting and a more robust definition of internal auxiliary functions. Element-level simulations are performed to compare the outputs within a group of selected E-FEM approaches, including the novel proposal. Simulations show that the new element formulation grants a wider level of basic kinematic coherence between the local fracture outputs and element kinematics, demonstrating an increase in robustness that might drive the usefulness of E-FEM techniques for fracture simulations to a higher level.

Modelling of triaxial fracture processes in heterogeneous quasi-brittle materials using the Embedded Finite Element Method (E-FEM)

This paper studies the use of the Embedded Finite Element Method (E-FEM) for the numerical modelling of triaxial fracture processes in non-homogeneous quasi-brittle materials. The E-FEM framework used in this study combines two kinematics enhancements: a weak discontinuity allowing the model to account for material heterogeneities and a strong discontinuity allowing the model to represent local fractures. The strong discontinuity features enriched fracture kinematics that allow the modelling of all typical fracture modes in three dimensions. A brief review is done of past work using similar enriched finite element frameworks to approach this problem. The work continues by establishing the theoretical basis of each kind of discontinuity formulation and their superposition through the Hu-Washizu variational principle. Afterwards, two groups of simulations have been done for discussing the performance of this combined E-FEM model: homogeneous simulations and simple heterogeneous simulations. Simple homogeneous material simulations aim to test the capabilities of the strong discontinuity model featuring full 3-D kinematics. Simple heterogeneous simulations show numerical applications of the model to the problem of a single spherical inclusion embedded into a homogeneous matrix. Comparisons will be made with another E-FEM model considering a single local fracture mode approach to discuss the differences on the representation of fracture physics under all explored conditions. A concluding statement is made on the benefits and complications identified for the E-FEM framework in this kind of applications.