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UCL Department of Chemical Engineering

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ThAMeS: The Advanced Multiphase Systems

Research focusing on the flow and transport phenomena in complex two-phase systems.

About

We study the flow and intensified processing of complex multiphase mixtures. We are interested, in particular, in immiscible liquid-liquid mixtures, as well as particle or bubble suspensions in non-Newtonian fluids for energy and manufacturing applications. The aim of the research is to gain fundamental insights of the underpinning small scale flow and interfacial phenomena and their interactions with mass transfer, that we use to understand the global behaviour of the multiphase processes and to develop predictive models.

Our work is supported by state of the art experimental facilities that include pilot scale flow rigs for studies of oil-water flows and processing of complex fluids, and bench scale setups for intensified and microscale flow and mass transfer studies.

We have available advanced instrumentation for studying velocity and concentration profiles (Particle Image Velocimetry, PIV and micro-PIV, hot film anemometry, Laser Induced Fluorescence), phase distribution (Electrical Resistance Tomography, ERT), rheology and interfacial properties, as well as a variety of local conductivity probes, made in-house, for investigating drop size, interface positioning and phase continuity. 

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Study areas

The studies address areas such two-phase liquid flows in pipelines relevant to flow assurance in oil production and transportation, intensified liquid-liquid extractions and reactions for spent nuclear fuel reprocessing,  metal separations and biofuel production, and processing of suspensions in complex fluids for healthcare applications.

Large scale liquid-liquid flows

The flow of oil and water inside a pipe is an important phenomenon which is often found in chemical and oil & gas industries, for example during transportation of crude oil and water mixture over long distances from offshore to onshore platforms. It is known when the two fluids flow together, they can flow in different flow patterns and each pattern can give arise to different pressure drop and energy consumption. With limited availability of the resources, it has now become essential to be able to predict accurately the flow patterns for increased production efficiency and for safety purposes as well as for future design of the system.

Our team aims to characterize and understand different oil-water flow phenomena, focusing on different regions of the flow pattern map through both experimental and numerical investigations. Different inlet geometries, channel sizes and fluid properties are currently being studied. High speed camera is extensively used for flow pattern identification and to extract data such as drop sizes and wave characteristics. PIV and High Speed PIV are used to gain better understanding of the flows and a wide range of conductance probes are used to capture interfacial phenomena. Simulation results are compared against experimental data and used to design future experiments.

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Microfluidics

Microfluidic devices in the range of a few hundred μm have received increased attention over the last decade driven by process intensification demands, notably in two-phase operations.  With advantages such as thinner fluid layers and large surface-to-volume ratio, heat and mass transfer rates are significantly better and when coupled with narrow residence time distributions, a higher efficiency process can be achieved.

Our group aims to gain fundamental understanding of micro-flow phenomena in two-phase systems. Studies involving interfacial mass transfer and recirculation patterns can be achieved with the state-of-the-art equipment within our research laboratory, such as, Laser Induced Fluorescence (LIF) and micro Particle Image Velocimetry (µPIV). Currently, there are multiple ongoing research involving droplets formations and the displacement process within the microfluidic system.

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Intensified Processes

In ThAMeS, we develop innovative intensified technologies that have a direct impact on the energy industry and particularly the nuclear, biofuel, and hydrometallurgy sectors. 

Main applications

The main use of these technologies is in the recycling and reprocessing of metallic components from the (nuclear) waste, and thus reducing the amount of metals needed to be mined and reducing the volume (and toxicity) of the rest of the waste. In the production of biofuels new approaches based on waste oils and fats are substituting earlier ones that are controversially competing with crops for food.

Intensified reactors

Processes are performed in intensified, small-scale units (micro to milli scale), which reduce the amount of solvent volume required, and make possible the use of expensive solvents such as ionic liquids. The reduction in volume is compensated by the high efficiencies achieved. Rapid and efficient mixing is an important trait in these processes and is significantly enhanced in small channels by the short diffusion lengths, recirculation, and convection induced by surface tension gradients. The industrial application of intensified units requires a good understanding of the whole system and in ThAMeS we perform full hydrodynamic & mass transfer characterisation of the key features on multiphase flows. 

Scale-up strategies

In ThAMeS there is ongoing research to increase throughput using small-scale devices. Scale-out (or number-up), which is the use of parallel channels to increase the throughput in the two-phase contacting equipment, is mainly used instead of conventional scale-up (increase in size). The objective is to design multichannel reactors and increase the total processing capacity of the process. This is achieved by using novel methodologies based on resistance network models for multiphase mixtures.

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Coalescence Phenomena

In long-distance oil transportation, the coalescence of water or oil droplets affects the pressure drop and energy consuming. Previous studies reveal that drop coalescence is influenced by the fluid properties (density, viscosity and interfacial tension) and the operation conditions such as the relative velocity between two coalescence bodies. This research aims to find how the fluid properties and operation conditions affect the coalescence process and build models to predict the coalescence rate.

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Processing of Complex Fluids

Non-Newtonian fluids, such as paint, toothpaste, blood are ubiquitous in nature, and they are widely used in chemical engineering, bio-chemical engineering, food processing, oil exploration, and medical engineering. 

In our group we use both experimental optical techniques and computational fluid dynamics to obtain critical information of different physical systems and tackle new manufacturing challenges. Specifically, our main interest focuses on the mixing of complex non-Newtonian liquid-liquid and solid-liquid mixtures in both batch and continuous processes with an insight into the rheological properties of the materials used.

Complex fluids

Giovanni mixing

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