Numerical Simulation of Sterilization Processes for Shear‐Thinning Food in Taylor‐Couette Flow Systems

The performance of the Taylor‐Couette flow apparatus as a heat sterilizer is numerically investigated. The destruction of Clostridium botulinum and thiamine (vitamin B1) was selected as model reaction. When Taylor vortices were formed in the annular space, the heat transfer significantly enhanced as compared to the case without vortex flow. As a result, the equivalent lethality calculated from the temperature field increased, which is regarded as a quantum leap. Conversely, the improvement of heat transfer induced destruction of thiamine. These results suggest that there is a trade‐off relationship between the enhancement of heat transfer and the avoidance of thermal destruction of nutritional components. In conclusion, the Taylor‐Couette flow sterilizer has the potential for process intensification in heat sterilization processes.     

Real‐time Dynamic Optimization of Non‐linear Batch Systems

In this paper, a methodology for designing and implementing a real time optimizing controller for non‐linear batch processes is discussed. The controller is used to optimize the system input and state trajectories according to a cost function. An interior point method with penalty function is used to incorporate constraints into a modified cost functional, and a Lyapunov‐based extremum seeking approach is used to compute the trajectory parameters. Smooth trajectories were generated with reduced computing time compared to many optimizations in literature. In this paper, the theory is applied to general non‐flat non‐linear systems in a true on‐line optimization.     

Heterogeneous Catalytic Reactor Design with Non‐Uniform Catalyst Considering Shell‐Progressive Poisoning Behavior

A novel methodology has been developed to design an optimum heterogeneous catalytic reactor, by considering non‐uniform catalyst pellet under shell‐progressive catalyst deactivation. Various types of non‐uniform catalyst pellets are modelled in combination with reactor design. For example, typical non‐uniform catalyst pellets such as egg‐yolk, egg‐shell and middle‐peak distribution are developed as well as step‐type distribution. A progressive poisoning behavior is included to the model to produce correct effectiveness factor from non‐uniform catalyst pellet. As opposed to numerical experiment with limited type of kinetic application to the model in the past, this paper shows a new methodology to include any types of kinetic reactions for the modeling of the reactor with non‐uniform catalyst pellet and shell‐progressive poisoning. For an optimum reactor design, reactor and catalyst variables are considered at the same time. For example, active layer thickness and location inside pellet are optimised together with reactor temperature for the maximisation of the reactor performance. Furthermore, the temperature control strategy over the reactor operation period is added to the optimization, which extends the model to three dimensions. A computational burden has been a major concern for the optimization, and innovative methodology is adopted. Application of profile based synthesis with the combination of SA (Simulated Annealing) and SQP (Successive Quadratic Programming) allows more efficient computation not only at steady state but also in dynamic status over the catalyst lifetime. A Benzene hydrogenation reaction in an industry scale fixed‐bed reactor is used as a case study for illustration.     

Fault Detection of Non‐Linear Processes Using Kernel Independent Component Analysis

In this paper, a new non‐linear process monitoring method based on kernel independent component analysis (KICA) is developed. Its basic idea is to use KICA to extract some dominant independent components capturing non‐linearity from normal operating process data and to combine them with statistical process monitoring techniques. The proposed method is applied to the fault detection in the Tennessee Eastman process and is compared with PCA, modified ICA, and KPCA. The proposed approach effectively captures the non‐linear relationship in the process variables and showed superior fault detectability compared to other methods while attaining comparable false alarm rates.     

Non‐asbestos Diaphragms in Chlor‐Alkali Electrolysis

For decades in diaphragm electrolysis, asbestos containing diaphragms have been utilized to separate the anode and cathode compartments. Due to the harmful characteristics of asbestos, its world‐wide prohibition in diaphragm manufacturing is expected. The objective of this work was focussed on the development of a diaphragm with sufficient mechanical and chemical stability to substitute the modified asbestos diaphragm currently used. Suitable materials for the manufacture of non‐asbestos diaphragms were identified and a deposition technology was developed which fulfils the requirements of industrial production plants.     

Mathematical Modelling of Non‐Isothermal Venturi Scrubbers

A mathematical model consisting of differential equations for energy, momentum and material exchange is developed for a non‐isothermal Venturi‐type scrubber. By this model, the effects of heat and mass transfer on droplets concentration distribution and removal efficiency of particulate in a non‐isothermal Venturi scrubber can be investigated. In order to approach a realistic model, the liquid film flow on the walls and droplet size distribution are considered. The model is validated by comparing the results of mathematical model by plant and experimental data reported in the literature. The Results section of this work reveals that the inlet humidity and temperature of the gas can affect the removal efficiency of the scrubber.     

Optimization of Fischer‐Tropsch Process in a Fixed‐Bed Reactor Using Non‐uniform Catalysts

Optimization of Fischer‐Tropsch (FT) process in a fixed‐bed reactor is carried out using non‐uniform catalysts. The C₅⁺ yield of the reactions is maximized utilizing a combination of non‐uniform catalysts across the bed. A 1D heterogeneous model is developed to simulate the bed containing uniform and non‐uniform catalysts. It is found that the egg‐shell and surface‐layered catalysts result in higher C₅⁺ yield. Moreover, effects of cooling temperature are studied. Genetic Algorithm (GA) and Successive Quadratic Programming (SQP) methods are applied. Feed and cooling temperature are selected as decision variables together with distribution of non‐uniform catalysts along the bed. The optimization result shows 14.47 % increase in the C₅⁺ yield with respect to the base condition.     

Numerical Simulation of Open‐Circuit Continuous Mills Using a Non‐Linear Population Balance Framework: Incorporation of Non‐First‐Order Effects

Population balance modeling has been used as a tool for simulating, optimizing, and designing various particulate processes, including milling. A fundamental tenet of the traditional models for milling processes is the first‐order breakage kinetics. Ample data obtained from batch milling studies show that this assumption is not necessarily valid for certain milling systems. In the present theoretical investigation, an attempt has been made to incorporate these experimentally observed non‐first‐order effects into continuous mill models within the context of a novel non‐linear population balance framework. In view of two idealized flow regimes, i.e., perfect mixing and plug‐flow, continuous mills operating in the open‐circuit mode are numerically simulated. The simulations indicate that not only does the product size distribution depend on the degree of mixedness in a continuous mill, but also on the non‐first‐order effects arising from multi‐particle interactions.     

交变载荷对脉动真空灭菌器内腔开裂影响的研究

针对脉动真空灭菌器内壳与横加强筋末端焊接区产生裂纹的问题,应用ANSYS有限元分析软件对其进行交变载荷疲劳分析。其结论对脉动真空灭菌器的设计及优化均有参考价值。     

Influence of Non‐Condensable Gases on the Dynamic Behaviour of an Auto‐Refrigerated CSTR Polymerization Reactor

A polymerization reactor connected to a semi‐flooded horizontal condenser is presented. A model of the process was developed, taking into account the influence of non‐condensable gases in the system. The results obtained show that the model developed was able to reproduce the major dynamic characteristics, even with the presence of non‐condensable gases. It is shown that the non‐condensable gases have great influence on the reactor state, which never reaches a steady‐state; these gases accumulate in the system, increasing the pressure and temperature, and reducing the area of contact and the mass of liquid, therefore needing to be purged regularly, otherwise the system will collapse.     

Advantages of Forced Non‐steady Operated Trickle‐Bed Reactors

Trickle‐bed reactors are usually operated in the steady state trickle flow regime. Uneven liquid distribution and the formation of hot spots are the most serious problems experienced during trickle flow operation. In this paper, we advocate the use of non‐steady state operation of trickle‐bed reactors. Based on a square‐wave cycled liquid feed, several operation modes are developed that involve the artificial induction of natural pulses and control of the catalyst wetting efficiency over longer times. The operation modes aim at increasing the mass transfer rate of the limiting reactant and simultaneous prevention of flow maldistribution and hot spot formation. The operation modes are distinguished by a relatively fast and slow cycling of the liquid feed. The potential advantages of the developed feed strategies on reactor performance are evaluated.     

Thermooxidative stability of vegetable oils refined by steam vacuum distillation and by molecular distillation

Semi‐refined rapeseed and sunflower oils after degumming and bleaching were refined by deodorization and deacidification in two ways, i.e., by steam vacuum distillation in the deodorization column Lurgi and by molecular distillation in the wiped‐film evaporator. The oxidative stability of the oils before and after the physical refining has been evaluated using non‐isothermal differential scanning calorimetry. Treatment of the experimental data was carried out by applying a new method based on a non‐Arrhenian temperature function. The results reveal that refining by molecular distillation leads to lower oxidative stability of the oils than refining by steam vacuum distillation. Practical applications : (i) A method for the refining of edible oils by the molecular distillation in the wiped film of a short‐path evaporator is presented and applied. (ii) Oxidative stability of the oils refined by molecular distillation and steam vacuum distillation is compared. It has been found that refining by molecular distillation leads to lower oxidative stability of the oils than refining by steam vacuum distillation. (iii) Experimental data were treated by applying a new method based on a non‐Arrhenian temperature function. The method enables trustworthy predictions of oil stabilities for the application temperatures.     

A Note on Non‐Negative Arma Processes

Abstract. Recently, there has been much research on developing models suitable for analysing the volatility of a discrete‐time process. Since the volatility process, like many others, is necessarily non‐negative, there is a need to construct models for stationary processes which are non‐negative with probability one. Such models can be obtained by driving autoregressive moving average (ARMA) processes with non‐negative kernel by non‐negative white noise. This raises the problem of finding simple conditions under which an ARMA process with given coefficients has a non‐negative kernel. In this article, we derive a necessary and sufficient condition. This condition is in terms of the generating function of the ARMA kernel which has a simple form. Moreover, we derive some readily verifiable necessary and sufficient conditions for some ARMA processes to be non‐negative almost surely.     

Bubble Volume and Aspect Ratio Generated in Non‐Newtonian Fluids

Bubble formation from an orifice submerged in quiescent polyacrylamide aqueous solution was investigated numerically with a sharp‐interface coupled level‐set/volume‐of‐fluid method based on the rheological characteristics of the fluid. In both non‐Newtonian fluids and Newtonian fluids, the numerical approach was able to capture accurately the deformation of the bubble surface, validated by comparison with experimental results. The effects of orifice diameter, solution mass concentration, and gas flow rate on bubble volume and aspect ratio were evaluated. Both the instantaneous and detached volume decrease with the orifice diameter but increase with mass concentration and gas flow rate. The aspect ratio at the departing point tends to rise with the orifice diameter and mass concentration and falls with the gas flow rate.     

Residence Time Distribution Models Derived from Non‐Ideal Laminar Velocity Profiles in Tubes

The theoretical E‐curve for the laminar flow of non‐Newtonian fluids in circular tubes may not be accurate for real tubular systems with diffusion, mechanical vibration, wall roughness, pipe fittings, curves, coils, or corrugated walls. Deviations from the idealized laminar flow reactor (LFR) cannot be well represented using the axial dispersion or the tanks‐in‐series models of residence time distribution (RTD). In this work, four RTD models derived from non‐ideal velocity profiles in segregated tube flow are proposed. They were used to represent the RTD of three tubular systems working with Newtonian and pseudoplastic fluids. Other RTD models were considered for comparison. The proposed models provided good adjustments, and it was possible to determine the active volumes. It is expected that these models can be useful for the analysis of LFR or for the evaluation of continuous thermal processing of viscous foods.     

On non‐combustibility of commercial building materials

Non‐combustibility is discussed on the basis of experimental data for 66 commercial building materials obtained from two standard test methods: EN ISO 1716 oxygen bomb calorimeter and EN ISO 1182 cylindrical furnace. The sample materials are divided into five categories: concrete and ceramics, thermal/acoustic insulation materials, wall or ceiling boards, mortars and adhesives and thin coatings. To better distinguish between non‐combustible and combustible materials, an effective modified heat of combustion is defined and calculated for all materials tested in both methods. The materials studied exhibited very different mass loss values and a low tendency to auto‐ignite in the cylindrical furnace. Revised criteria for class A1 are proposed for better accuracy of reaction‐to‐fire assessment. It is proposed to use the oxygen bomb calorimeter with only one limit for the heat of combustion, that is, a value of 5 MJ/kg for all materials. The proposed approach is a very efficient tool for fast and inexpensive screening for non‐combustibility of building products and is expected to be a more precise method to distinguish between non‐combustible and combustible materials. Copyright © 2016 John Wiley & Sons, Ltd.     

A Three‐Dimensional Non‐isothermal Model of High Temperature Proton Exchange Membrane Fuel Cells with Phosphoric Acid Doped Polybenzimidazole Membranes

High temperature proton exchange membrane fuel cells (HT‐PEMFCs) with phosphoric acid doped polybenzimidazole (PBI) membranes have gained tremendous attentions due to its attractive advantages over conventional PEMFCs such as faster electrochemical kinetics, simpler water management, higher carbon monoxide (CO) tolerance and easier cell cooling and waste heat recovery. In this study, a three‐dimensional non‐isothermal model is developed for HT‐PEMFCs with phosphoric acid doped PBI membranes. A good agreement is obtained by comparing the numerical results with the published experimental data. Numerical simulations have been carried out to investigate the effects of operating temperature, phosphoric acid doping level of the PBI membrane, inlet relative humidity (RH), stoichiometry ratios of the feed gases, operating pressure and air/oxygen on the cell performance. Numerical results indicate that increasing both the operating temperature and phosphoric acid doping level are favourable for improving the cell performance. Humidifying the feed gases at room temperature has negligible improvement on the cell performance, and further humidification is needed for a meaningful performance enhancement. Pressurising the cell and using oxygen instead of air all have significant improvements on the cell performance, and increasing the stoichiometry ratios only helps prevent the concentration loss at high current densities.     

Simulation‐Based Design of Dual‐Mode Controller for Non‐Linear Processes

This paper presents a simulation‐based approach for designing a non‐linear override control scheme to improve the performance of a local linear controller. The higher‐level non‐linear controller monitors the dynamic state of the system and calculates an override control action whenever the system is predicted to move outside an acceptable operating regime under the local controller. The design of the non‐linear override controller is based on a cost‐to‐go function, which is constructed by using simulation or operation data. The cost‐to‐go function delineates the admissible region of state space within which the local controller is effective, thereby yielding a switching rule.     

On Measuring Closed‐Loop Non‐Linearity: A Topological Approach

The focal point of this paper is to develop a measure of closed‐loop non‐linearity. In this work, the Vinnicombe metric and the Quasi‐Linear Parameter Varying representation of a non‐linear system are exploited for this purpose. It is expected that the proposed measure can serve as a decision making tool for control engineers when considering whether a linear or a non‐linear control strategy should be employed to close the loop for a non‐linear system operating in a prescribed range.     

Catalytic Non‐Enzymatic Kinetic Resolution

While tremendous advances have been made in asymmetric synthesis, the resolution of racemates is still the most important industrial approach to the synthesis of chiral compounds. The use of enzymes for the kinetic resolution (KR) of racemic substrates to afford enantiopure compounds in high enantioselectivity and good yield has long been a popular strategy in synthesis. However, transition metal‐mediated and more recently organocatalyzed KRs have gained popularity within the synthetic community over the last two decades due to the progress made in the development of chiral catalysts for asymmetric reactions. Many catalytic non‐enzymatic procedures have been developed providing high enantioselectivity and yield for both products and recovered starting materials. Indeed, the non‐enzymatic KR of racemic compounds based on the use of a chiral catalyst is presently an area of great importance in asymmetric organic synthesis. The goal of this review is to provide an update on the principal developments of catalytic non‐enzymatic KR covering the literature since 2004. This review is subdivided into seven sections, according to the different types of compounds that have been resolved through catalytic non‐enzymatic KR, such as alcohols, epoxides, amines, alkenes, carbonyl derivatives, sulfur compounds and ferrocenes. Abbreviations: Ac: acetyl; acac: acetylacetone; AQN: anthraquinone; Ar: aryl; Atm: atmosphere; BINAM: 1,1′‐binaphthalenyl‐2,2′‐diamine; BINAP: 2,2′‐bis(diphenylphosphanyl)‐1,1′‐binaphthyl; BINEPINE: phenylbinaphthophosphepine; BINOL: 1,1′‐bi‐2‐naphthol; Bmim: 1‐butyl‐3‐methylimidazolium; Bn: benzyl; Boc: tert‐butoxycarbonyl; Box: bisoxazoline; BSA: bis(trimethylsilyl)acetamide; Bu: butyl; Bz: benzoyl; c: cyclo; CBS: Corey–Bakshi–Shibata; Cbz: benzyloxycarbonyl; COD: cyclooctadiene; COE: cyclooctene; Cy: cyclohexyl; Dba: (E,E)‐dibenzylideneacetone; DBU: 1,8‐diazabicyclo[5.4.0]undec‐7‐ene; DCC: N,N′‐dicyclohexylcarbodiimide; de: diastereomeric excess; DEAD: diethyl azodicarboxylate; Dec: decanyl; DHQD: dihydroquinidine; Difluorphos: 5,5′‐bis(diphenylphosphino)‐2,2,2′,2′‐tetrafluoro‐4,4′‐bi‐1,3‐benzodioxole; DIPEA: diisopropylethylamine: DKR: dynamic kinetic resolution; DMAP: 4‐dimethylaminopyridine; DMSO: dimethyl sulfoxide; DNA: deoxyribonucleic acid; DOSP: N‐(dodecylbenzenesulfonyl)prolinate; DTBM: di‐tert‐butylmethoxy; ee: enantiomeric excess; Et: ethyl; equiv.: equivalent; Fu: furyl; Hex: hexyl; HIV: human immunodeficiency virus; HMDS: hexamethyldisilazide; KR: kinetic resolution; L: ligand; LDA: lithium diisopropylamide; MAO: methylaluminoxane; Me: methyl; Ms: mesyl; MTBE: methyl tert‐butyl ether; Naph: naphthyl; nbd: norbornadiene; NBS: N‐bromosuccinimide; NIS: N‐iodosuccinimide; Pent: pentyl; Ph: phenyl; Piv: pivaloyl; PMB: p‐methoxybenzoyl; Pr: propyl Py: pyridyl; r.t.: room temperature; s: selectivity factor; Segphos: 5,5′‐bis(diphenylphosphino)‐4,4′‐bi‐1,3‐benzodioxole; (S,S′,R,R′)‐Tangphos: (1S,1S′,2R,2R′)‐1,1′‐di‐tert‐butyl‐(2,2′)‐diphospholane; TBS: tert‐butyldimethylsilyl; TBDPS: tert‐butyldiphenylsilyl; TCCA: trichloroisocyanuric acid ; TEA: triethylamine; TEMPO: tetramethylpentahydropyridine oxide; THF: tetrahydrofuran; Thio: thiophene; Tf: trifluoromethanesulfonyl; TMS: trimethylsilyl; Tol: tolyl; Ts: 4‐toluenesulfonyl (tosyl)