We study the macromixing behavior of single and multi-orifice-impinging transverse (MOIT) jet mixers with crossflow, in particular, the overall mixing time and the back-splash mixing time of the injected flow with the crossflow, using the PLIF technique. It is found that for a given mixer configuration, there is a critical jet-tocrossflow velocity ratio r_c at which the back-splash begins to occur. Further increase in the velocity ratio r leads to sharp increase in the back-splash mixing time, which can offset the intensification of the downstream mixing. The dimensionless overall mixing time decreases as r increases to reach either a plateau or a local minimum, and the corresponding r value represents the optimal velocity ratio r_opt for the macromixing. The momentumratio of the two liquid streams is a key factor determining r_c and r_opt. For a larger scale mixer, a higher momentum ratio is required to achieve the optimal macromixing with the minimum dimensionless overall mixing time.

The simulation of three-dimensional (3D) non-isothermal, non-Newtonian fluid filling process is an extremely difficult task and remains a challenging problem, which includes polymer melt flow with free surface coupled with transient heat transfer. This paper presents a full 3D non-isothermal two-phase flow model to predict the complex flowinmelt filling process,where the Cross-WLFmodel is applied to characterize the rheological behavior of polymer melt. The governing equations are solved using finite volume method with SIMPLEC algorithm on collocated grids and the melt front is accurately captured by a high resolution level set method. A domain extension technique is adopted to dealwith the complex cavities, which greatly reduces the computational burden. To verify the validity of the developed 3D approach, the melts filling processes in two thin rectangular cavities (one of them with a cylindrical insert) are simulated. The predicted melt front interfaces are in good agreement with the experiment and commercial software prediction. For a case with a rather complex cavity, the dynamic filling process in a hemispherical shell is successfully simulated. All of the numerical results show that the developed numerical procedure can provide a reasonable prediction for injection molding process.

Molecular layer deposition (MLD) for the deposition of polyimide (PI) at lowtemperature of 110℃ has been firstly introduced into the field of membrane separation.With the optimized MLD deposition parameters, such low deposition temperature has successfully expanded the application of MLD for the surface modification of polymeric materials. Globular PI particulates grow on both the free surfaces as well as the pore walls of the polypropylene (PP) membranes as isolated islands during progressive precursor exposures. The PI-deposited PP membranes exhibit synergistically improved performances in various aspects. Evidently improved surface hydrophilicity and permeation performance (30%) have been achieved via the MLD deposition of polyimide films. The overall separation efficiency maintained higher than 85% even after 250 cycles of MLD deposition. More importantly, the thermal stability has been improved and the integrity of the porous structure for PI-deposited PP membranes has been well preserved even after harsh treatment, which ensures its potential application in industries.

To prevent CO₂ accumulation in the atmosphere generated from scorching of fossil fuels, carbon capture and sequestration (CCS) technology is considered as a potential route to mitigate the emissions of CO₂ from reaching the atmosphere. Power generation from sources such as gas, coal and biomass can fulfill the energy demand more readily than many other sources of electricity production. Thus these sources may be retained as important alternative option in the global energy cycle. In order to curtail CO₂, porous aramid network was fabricated by the condensation of 1,3,5-benzenetricarbonyl trichloride and 1,3-phenylenediamine in 1,4-dioxane solvent. Aramid was characterized for various analyses including FTIR, XRD, TGA, BET surface area and pore size analysis, FESEM and CO₂ adsorption measurements. Excellent thermal stability was provided by strong amide linkages in the polymer backbone. Optimum CO₂ uptake of aramid was achieved to be 23.14 mg·g^-1 at 273 K at 0.1 MPa. The basic amide groups of network structure showed greater affinity for CO₂. Excellent thermal stability of aramid makes it a promising sorbent for CO₂ capture in adverse conditions.

Traditional data driven fault detection methods assume that the process operates in a single mode so that they cannot perform well in processes with multiple operating modes. To monitor multimode processes effectively, this paper proposes a novel process monitoring scheme based on orthogonal nonnegative matrix factorization (ONMF) and hidden Markov model (HMM). The new clustering technique ONMF is employed to separate data fromdifferent processmodes. ThemultipleHMMs for various operating modes lead to highermodeling accuracy. The proposed approach does not presume the distribution of data in each mode because the process uncertainty and dynamics can bewell interpreted through the hidden Markov estimation. The HMM-based monitoring indication named negative log likelihood probability is utilized for fault detection. In order to assess the proposed monitoring strategy, a numerical example and the Tennessee Eastman process are used. The results demonstrate that this method provides efficient fault detection performance.

This paper presents some new dynamic interaction analysis approaches for square or non-square systems and a pairing evaluation method. For square stable systems, an open-loop approach is proposed, which features the tradeoff between the contributions of response time constant and delay time to relative gain. For non-square stable systems, an extension from the proposed open-loop approach for square systems is presented and the corresponding pairing procedure is given. No interaction analysis approach is perfect for all systems, so any recommended pairing needs to be examined. An evaluationmethod is proposed in closed-loop with optimal controllers for each loop and whether the pairing is appropriate can be evaluated through testing if the equivalent relative gain is within defined scope. The advantages and effectiveness of proposed interaction analysis approaches and pairing evaluation method are highlighted via several examples of industrial processes.

Fault detection and identification are challenging tasks in chemical processes, the aimof which is to decide out of control samples and find fault sensors timely and effectively. This paper develops a partitioning principal component analysis (PPCA) method for process monitoring. A variable reasoning strategy is proposed and applied to recognize multiple fault variables. Compared with traditional process monitoring methods, the PPCA strategy not only reflects the local behavior of process variation in each model (each direction of principal components), but also improves the monitoring performance through the combination of local monitoring results. Then, a variable reasoning strategy is introduced to locate fault variables. Unlike the contribution plot, this method locates normal and fault variables effectively, and gives initiatory judgment for ambiguous variables. Finally, the effectiveness of the proposed process monitoring and fault variable identification schemes is verified through a numerical example and TE chemical process.

Alarm systems play important roles for the safe and efficient operation of modern industrial plants. Critical alarms are configured with a higher priority and are safety related among many other alarms. If critical alarms can be predicted in advance, the operator will have more time to prevent them from happening. In this paper, we present a dynamic alarm prediction algorithm, which is a probabilistic model that utilizes alarm data from distributed control system, to calculate the occurrence probability of critical alarms. It accounts for the local interdependences among the alarms using the n-gram model, which occur because of the nonlinear relationships between variables. Finally, the dynamic alarm prediction algorithm is applied to an industrial case study.

Stabilizing unstable operating points is an effectiveway to enhance process benefits and safety, which motivates the development for a variety of advanced control strategies. The washout filter-aided controller (WFC), originally used for electric power system and aircraft, has been introduced to adjust the dynamic behavior of chemical process. However, the parameter tuning method faces two major limitations:the dimension of operating variables must be equal to or greater than that of state variables and only one positive real eigenvalue exists in the open loop system. To overcome the two limitations, this paper proposes a new parameter tuning method, so that theWFC is applicable in most chemical processes. By solving a constrained optimization problem, the controller parameters are determined under the constraint that the reassignment of the eigenvalues of the unstable desired operating point can satisfy the stability condition. Thus parts of the equilibrium manifold including the desired operating point are stabilized without affecting the shape of the equilibrium manifold. Finally, the effectiveness of the WFC improved by the proposed parameter tuning method is illustrated through a case study for propanediol anaerobic fermentation.

Introducing purifiers into hydrogen network can enhance the recovery and reuse of hydrogen in refineries, further reducing the consumption of fresh hydrogen. Based on previous graphical methods, this work proposes a simple and unified graphical method for integration of hydrogen networks with purification processes. Scenarios with different hydrogen concentrations of purified product can be analyzed by the unified procedure. As a result, the maximum hydrogen saved by purification reuse can be identified and the corresponding purification process can be optimized. The proposed method is easy and non-iterative, and it is valid to purification processes with any feed concentration. A conventional hydrogen network is analyzed to test the effectiveness of the proposed method.

In order to increase the productivity of microreactors, the parallelization of the microreactors is required. The performances of flowdistributors can affect the product yield and fault detection abilitywhen blockage happens. In this research, an optimal design method to calculate the channel diameters and to determine the flow sensor location is derived based on mass balance and pressure balancemodels of split-and-recombine-type flow distributors (SRFDs). The model accuracy is verified by experiment data. The proposed method is applied to optimal design of SRFDs under constant flowrate operation conditions. The maximumangle difference between normal and blockage conditions at one sensor to those at the other sensors is set to be the objective function and the uniformity of flow distribution in microreactors under normal condition is also required. The diameters of each pipe in SRFDs are selected as the design variables. Simulated annealing algorithmis used to solve the optimization problem. The effectiveness of the optimal design results is demonstrated by fluid dynamics simulations. The results show that using the optimal channel diameters of SRFDs, the pressure drop in SRFD section is lower than that of the microreactor section. Meanwhile, in the case studies, only a few sensors that are located inside the SRFDs can easily detect the blockage abnormal condition in the parallelized microreactor system.

Density functional theory has been confirmed as a reliable approach in the descriptions of inhomogeneous fluids. By integrating the density functional theory into the revised local average density model, a theoretical approach is constructed to investigate the local shear viscosity in the confined conditions. In the density functional theory, the weighted density approximation for attractive part and the modified fundamental measure theory for repulsion contribution are adopted to accurately describe the inhomogeneous systems. By comparingwith simulation data, the theoretical model is tested. In this work, the shear viscosities of methane are calculated in different external fields (on a hard wall, a solvophobicwall and in slit pores with different widths). In addition, the effects of temperature on the local density and viscosity are also considered. It shows that the effect of temperature on the shear viscosity ismore obvious on solid surfaces. The calculation provides an approach to determine the viscosity under confined conditions, which is extremely significant in real industrial applications.

The activity of whole-cell biocatalysts is strongly compromised by the cell envelope, which is a permeability barrier against the diffusion of substrates and products. Although common chemical or physical permeabilization methods used in cultured cells enhance cell permeability, these methods inevitably add several extra processing steps after cell cultivation, aswell as impede large scale processing. To increase membrane permeability and cellbound glutamate decarboxylase (GAD) activity of recombinant Escherichia coli (BL21(DE3)-pET28a-gadB) cells without the need for an additional permeabilization step, we investigated the permeabilizing effects of adding cell wall synthesis inhibitors or surfactants to the culture media. Ampicillin was the most effective at improving cell-bound GAD activity of the BL21(DE3)-pET28a-gadB, although it decreased the cell biomass yield. The best permeabilization effect was observed using an ampicillin concentration of 5 μg·ml^-1. Using this concentration, the cell biomass did decrease by 40.58%, but the cell-bound GAD activity of BL21(DE3)-pET28a-gadB and total cell-bound GAD activity per milliliter of culture was enhanced by 6.24- and 3.64-fold, respectively. Treatment of BL21 (DE3)-pET28a-gadB cells with 5 μg·ml^-1 ampicillin resulted in structural changes to the cell envelope, but did not substantially affect GAD expression. By entrapping the ampicillin-treated cells in an open pore gelation matrix, which is a polymer derived from polyvinyl alcohol (PVA), alginate, and boric acid, the transformation rate of γ-aminobutyric acid (GABA) at the 10th cycle produced by immobilized and permeabilized cells remained 46% of the first cycle. GAD activity of the immobilized, permeabilized cells remained over 90% after 30 days of storage at 4℃.

Vanadiumoxide (VO_x) nanostructures, synthesized by hydrothermal treatment using dodecylamine as template, were evaluated for the selective catalytic reduction of NOx with ammonia (NH₃-SCR). The effect of solvent type in the reaction mixture (EtOH/(EtOH+H₂O)) and time of hydrolysis was studied. The obtained materials were characterized by XRD, SEM, TEM and BET. The VO_x nanorods (80-120 nm diameter and 1-4 μm length) were synthesized in 25 vol% EtOH/(EtOH+H₂O) and the open-ended multiwalled VO_x nanotube (50-100 nm inner diameter, 110-180 nm outer diameter and 0.5-2 μm length) synthesized in 50 vol% EtOH/(EtOH+H₂O). VO_x nanotubes performed the superior NH₃-SCR activity under a gas hourly space velocity of 12,000 h^-1 at low temperature of 250℃ (NO_x conversion of 89% & N₂ selectivity of 100%), while most of the developed Vanadia base catalysts are active at high temperature (>350℃). The superior NH₃-SCR activity of VO_x nanotubes at low temperature is related to nanocrystalline structure, special nanotube morphology as well as high specific surface area.

Biomethane has been developed rapidly in many countries as a renewable energy which upgraded from biogas. China also began to pay attention to it even though we still at a initial stage, primarily, understanding the biomethane potential and development prospect, choosing appropriate biomass as the biomethane source is very important. In this work, the theoretical and practical biomethane producing potential from five main biomass resources in China were estimated with appropriate methods based on the data collected, and during calculation, two appropriate energy crops were assumed to be planted on marginal lands for biomethane production. Our estimation showed that the theoretical and practical biomethane potentials in China can reach to 888.78 and 316.30 billion m³ per year, agricultural waste should be the preferential development biomass, and planting energy crops on marginal lands is the most promising way to enhance biomethane production in China. Finally, biomethane is compared with natural gas, and the result showed that 48.15% of the practical biomethane potential can meet the total Chinese natural gas consumption in 2013.

Solidification or crystallization of phase change emulsion in the form of fine emulsion drops in a direct contact coolant at temperatures below their freezing point was studied. This work is mainly focused on the size and shape of the generated particles from phase change emulsified fats. Size of the particles is the major or key factor being considered during their formation, however, other factors that govern the particle size and shapewere also observed. The operating parameters of the process were optimized in order to obtain particles of smaller size ranges in the window of current operating conditions. The crystallization of complex emulsion matrices is very difficult to control in the bulk at desired requirement. Hence, the emulsion drop to particle formation has advantage in comparison with the bulk solidification or crystallization. The main objective of this work is to achieve spherical emulsion particles in a direct contact cooling system. Parameters like:stability, characterization, viscosity, and the effect of different energy inputs were examined. Moreover, the effects of the capillary size, interfacial tension, temperature of the emulsion on the particle size were also monitored.

The effect of particle size of silica, as catalyst binder, on the chemical and mechanical properties of iron based FT catalyst was studied in this work. The samples were characterized using XRD, BET, TEM, FT-IR, and H2-TPR, respectively. The attrition resistance and the FT activity were tested. Si-8-Si-15 catalysts prepared with 8-15 nm silica sol show good attrition resistance (attrition loss<4%), especially Si-13 with an attrition loss of 1.89%. Hematite appeared in XRD patterns when silica sol above 15 nm is used. TEM micrographs show that no obvious SiO₂ particles appear when silica sol particle with size less than 8 nm was used, but SiO₂ particles coated with small ferrihydrite particles appear when silica sol above 8 nm was used. Si-O-Si vibration peak in FT-IR spectra increases with increasing silica sol size. Samples prepared with silica sol show good stability of FT reactions, and the average molecular weight of FT products increases with the increase of SiO₂ particle.