A fixed grid numerical modelling methodology for convection-diffusion mushy region phase-change problems

The melting of pure gallium in a rectangular cavity has been numerically investigated using the enthalpy-porosity approach for modeling combined convection-diffusion phase change. The major advantage of this technique is that it allows a fixed-grid solution of the coupled momentum and energy equations to be undertaken without resorting to variable transformations. In this work, a two-dimensional dynamic model is used and the influence of laminar natural-convection flow on the melting process is considered. Excellent agreement exists between the numerical predictions and experimental results available in the literature. The enthalpy-porosity approach has been found to converge rapidly, and is capable of producing accurate results for both the position and morphology of the melt front at different times with relatively modest computational requirements. These results may be taken to be a sound validation of this technique for modeling isothermal phase changes in metallurgical systems.

Enthalpy-porosity technique for modeling convection-diffusion phase change: application to the melting of a pure metal

On the solution of population balance equations by discretization—II. A moving pivot technique

A novel concept for convective heat transfer enhancement

A literature review of theoretical models for drop and bubble breakup in turbulent dispersions

A model for transitional breakage probability of droplets in agitated lean liquid-liquid dispersions

A simple graphical method for measuring inherent safety

Experimental measurements of transient drop size distributions in a stirred liquid-liquid dispersion (with low dispersed phase fraction) have been used concomitantly with population balance theory to recover the transition probability of droplet breakage, based on a similarity concept. The data remarkably uphold the proposed similarity hypothesis, and the estimated probability function displays the same qualitative trend as the model due to Narsimhan et al. (1979).

Analysis of drop size distributions in lean liquid‐liquid dispersions

Chemical process industries such as oil refineries, fertiliser plants, petrochemical plants, etc., which handle hazardous chemicals, are potential targets for deliberate actions by terrorists, criminals and disgruntled employees. Security risks arising out of these threats are real and must be assessed to determine whether the security measures employed within the facility are adequate or need enhancement. The essential steps involved are threat analysis, vulnerability analysis, security countermeasures, and emergency response. Threat analysis involves the study of identifying sources, types of threats, and their likelihood. Vulnerability analysis identifies the weaknesses in a system that adversaries can exploit. Depending on the threat likelihood and vulnerabilities, various security countermeasures are suggested to improve the plant security. Appropriate emergency response measures that could mitigate the consequences of a successful attack and concepts of inherently safer processes in the light of process security are also discussed in the paper. It is recognised that serious terrorist threats exist to the transport system of hazardous chemicals (by road, rail cars, ships, pipelines, etc.). However, that is not a part of this study, which concentrates on process plants and hazardous materials within immovable boundaries. A case study of a fertiliser plant is used to show the application of ideas presented.

Jai P. Gupta

Papers

A model for transitional breakage probability of droplets in agitated lean liquid-liquid dispersions

A simple graphical method for measuring inherent safety

Analysis of drop size distributions in lean liquid‐liquid dispersions

Site Security: for Chemical Process Industries

Inherently Safer Design—Present and Future