Droplet breakage and coalescence models for the flow of water-in-oil emulsions through a valve-like element

An experimental and theoretical study was carried out regarding the evolution of droplet size distributions for the flow of water in oil emulsions through a valve-like element that simulates a mixing valve. The water droplets had diameters in the 0.1–100 μm range, which includes droplets that are either smaller or larger than the Kolmogorov length scale for the experimental conditions. Droplet breakage and coalescence models that can be used for this size range were proposed. A simplified population balance model was developed to interpret the experimental data and solved by the method of classes. The model parameters were estimated by the orthogonal distance regression method. The simplifying assumption of the model was verified by global optimization using a parallel implementation of the particle swarm optimization method. The agreement between simulated and experimental droplet volume size distributions was good. The predictions of the DeBroukere mean diameter, d₄₃, were unbiased with mean errors of 8%.     

Analysis of ball mill grinding operation using mill power specific kinetic parameters

With a view to developing a sound basis for the design and scale-up of ball mills, a large amount of data available in the literature were analyzed for variation of the two key mill performance parameters: power specific values of the ‘absolute breakage rate of the coarsest size fraction’, S^*, and ‘absolute rate of production of fines’, F^*, with some of the important operating and design variables such as the mill speed, ball load, particle load, ball diameter and mill diameter. In general, values of both the mill performance parameters were found to vary significantly with the mill operating conditions. The nature and relative magnitude of variation for the two parameters also differed significantly. Moreover, the effect of any particular variable on the S^* and F^* values was found to be significantly different for different sets of operating conditions. It has been emphasized that, as the purpose of grinding is to produce fine particles, the mill design and scale-up work should be based mainly on the F^* parameters. Moreover, it is not correct to regard the S^* values to be independent of the mill design and operating variables as a general rule, especially for a fine analysis of the performance of the grinding systems.     

用切伦科夫计数法确定破损元件组件

本文介绍了切伦科夫计数原理，分析了反应堆冷却剂中活化产物，裂变产物的放射性特性；讨论了用切伦科夫计数确定反应堆破损元件组件的可行性。     

High-shear granulation: An investigation into granule breakage rates

Granule breakage is an important rate process in wet granulation that promotes product uniformity and controls product size and strength. In this work, a model to predict granule breakage is proposed and experimentally validated. The model assumes exponential of the surviving granules, dependent on a probability of breakage; a function of powder and binder properties, as well as operating parameters. Validation experiments were performed with a breakage-only granulator, filled with cohesive, non-granulating sand. Premade pellets made from lactose monohydrate and silicone oils were granulated at several impeller speeds, and the number of survivors was observed over time. The results revealed that the number of granules did indeed decay exponentially. It was found that the overall probability of breakage was inversely proportional to the capillary number. Moreover, the pore saturation played an important role in determining the probability of breakage, with higher pore saturations reducing breakage overall. A comparison with experimental data from literature revealed that the developed models agrees qualitatively with the experimental data, but is unable to fully capture the effect of powder properties and powder-binder interaction.     

Breakage of drops and bubbles in a stirred tank: A review of experimental studies

The rate of breakage of drops and bubbles (fluid particles) in stirred systems is of great consequence on mass,heat, and momentum transport phenomena. Therefore, over the years, the topic has gained a considerable attention fromthe researchers to study and characterize this phenomenon. In present work, the experimental studies of breakage phenomenon in a stirred tank in the last four decadeswere reviewed. The reviewhighlighted the investigated experimental conditions and the major findings concerning the breakagemechanismand the effect of operating conditions. The discrepancy and contradictions of the outcomes of those studies were specified and discussed. Experimental observations and conclusions concerning the breakage characterization parameters,such as deformation, breakage probability, breakage time, and breakage location were presented and commented on. Possible future refinements and prospective were recommended. The review indicated that there are clear discrepancies and contradictions between previous studies regarding the effect of some operating parameters and the values of breakage time, breakage probability, number of daughter particles, and breakage location relative to the impeller. In addition, there are still many scientific gaps that need to be studied and characterized in future by overcoming specific experimental difficulties and uncertainties.     

Energy and population balances in comminution process modelling based on the informational entropy

The results of theoretical and experimental studies of a comminution process are presented. There are two random functions: the selection function and the breakage function in the stochastic model based on a population balance. This model enables prediction of particle size distributions of comminution products after determination of both random functions. Maximum entropy method is used in the entropy model for determining the breakage function. Two cases are analysed, based on continuous and discrete particle size distribution functions of the fed material. Apart from mass balance, the energy balance of comminution process is also used. Searched form of breakage function is determined with the application of methodology of calculus of variations. The results of experimental identification of both models are presented. The parameters that occur in the discrete form of the selection and breakage functions were the identification objects. The results of experimental investigations of quartz sand single comminution in a laboratory jet mill provided an identification base. The experimentally identified results of the entropy model confirmed the adequacy of the theoretical analysis and demonstrated the possibility of adequate prediction of particle size distributions resulting from single comminution.     

Maximum Entropy Method in Comminution Modelling

This paper analyses the comminution process. There are two random functions: the selection function and the breakage function in the stochastic model based on population balance. Introducing the energy balance, applying the maximum informational entropy method and taking into consideration the normalized condition, enables us to formulate and solve the variational problem and determine the breakage function by Lagrange’s multipliers method. The above determination of the breakage function is an original new method. The sought form of the breakage function is an argument of the constrained extremum of an integral functional with two indirect conditions. The obtained form of the breakage function was applied to the equation of the population balance. This leads to the prediction of the particle size distribution of the single comminution product with an additional assumption concerning the form of the selection function.     

New wavelet-based adaptive method for the breakage equation

A new wavelet-based adaptive collocation method is formulated for the solution of breakage equations. The technique of grid adaptation is based on sparse point representation (SPR). Without loss of generality, the method is applied and tested for the cases of uniform binary breakup and multiple breakup. Accurate and convergent solutions are obtained and found to match the analytical solutions very well.     

冒落矸石自行充填沿空巷道矿压显现规律研究

结合葛泉煤矿1528工作面运输巷具体的煤层赋存条件和开采技术条件,通过在巷道内将强制切顶与矸石护帮融为一体的特种组合支护,研究试验了一种利用工作面内的冒落矸石进行巷旁自行充填的沿空留巷技术。通过大量的现场实测与对比分析,研究了受2次重复采动影响的巷道顶底板与两帮围岩的变形规律,得出了影响巷道围岩变形规律的主要因素,为实现冒落矸石自行充填沿空留巷技术的工程应用提供了理论依据和技术支持。