Elsa Aristodemou - Academia.edu (original) (raw)

Talks by Elsa Aristodemou

Papers by Elsa Aristodemou

Frontiers of Chemical Science and Engineering, Dec 8, 2020

With fossil fuel being the major source of energy, CO 2 emission levels need to be reduced to a m... more With fossil fuel being the major source of energy, CO 2 emission levels need to be reduced to a minimal amount namely from anthropogenic sources. Energy consumption is expected to rise by 48% in the next 30 years, and global warming is becoming an alarming issue which needs to be addressed on a thorough technical basis. Nonetheless, exploring CO 2 capture using membrane contactor technology has shown great potential to be applied and utilised by industry to deal with post-and pre-combustion of CO 2. A systematic review of the literature has been conducted to analyse and assess CO 2 removal using membrane contactors for capturing techniques in industrial processes. The review began with a total of 2650 papers, which were obtained from three major databases, and then were excluded down to a final number of 525 papers following a defined set of criteria. The results showed that the use of hollow fibre membranes have demonstrated popularity, as well as the use of amine solvents for CO 2 removal. This current systematic review in CO 2 removal and capture is an important milestone in the synthesis of up to date research with the potential to serve as a benchmark databank for further research in similar areas of work. This study provides the first systematic enquiry in the evidence to research further sustainable methods to capture and separate CO 2. Keywords CO 2 capture, preferred reporting items for systematic reviews and meta-analyses, membrane contactor, absorbent

Building and Environment, Nov 1, 2019

It is recognised worldwide that air pollution is the cause of premature deaths daily, thus necess... more It is recognised worldwide that air pollution is the cause of premature deaths daily, thus necessitating the development of more reliable and accurate numerical tools. The present study implements a three dimensional Variational (3DVar) data assimilation (DA) approach to reduce the discrepancy between predicted pollution concentrations based on Computational Fluid Dynamics (CFD) with the ones measured in a wind tunnel experiment. The methodology is implemented on a wind tunnel test case which represents a localised neighbourhood environment. The improved accuracy of the CFD simulation using DA is discussed in terms of absolute error, mean squared error and scatter plots for the pollution concentration. It is shown that the difference between CFD results and wind tunnel data, computed by the mean squared error, can be reduced by up to three order of magnitudes when using DA. This reduction in error is preserved in the CFD results and its benefit can be seen through several time steps after re-running the CFD simulation. Subsequently an optimal sensors positioning is proposed. There is a trade-off between the accuracy and the number of sensors. It was found that the accuracy was improved when placing/considering the sensors which were near the

NATO science for peace and security series, 2010

In 1969, the North Atlantic Treaty Organization (NATO) established the Committee on Challenges of... more In 1969, the North Atlantic Treaty Organization (NATO) established the Committee on Challenges of Modern Society (CCMS). From inception, the subject of air pollution was established as one of the priority problems for study within the framework of various pilot studies undertaken by this committee. The main activity within the pilot study relating to air pollution is the periodic organization of a major international conference dealing with air pollution modeling and its application.

Building Research and Information, Jun 28, 2018

RSC Advances, 2020

A Computational Fluid Dynamics (CFD) study has been conducted to assess the performance of packed... more A Computational Fluid Dynamics (CFD) study has been conducted to assess the performance of packed bed and coated wall microreactors for the steam reforming of methanol with a CuO/ZnO/Al 2 O 3 based catalyst (BASF F3-01). The results obtained were compared to experimental data from the literature to assess the validity and robustness of the models, and a good validation has been obtained. The performance of the packed bed and coated wall microreactors is similar at a constant reforming temperature. It was found that methanol conversion is enhanced with increasing temperature, residence time, steam to methanol ratio, and catalyst coating thickness. Furthermore, internal and external mass transfer phenomena were investigated using the models, and it was found that there were no internal and external mass transfer resistances for this reactor configuration. Further studies demonstrated that larger catalyst pellet sizes led to the presence of internal mass transfer resistance, which in turn causes lower methanol conversions. The CFD models have exhibited a sound agreement with the experimental data, hence they can be used to predict the steam reforming of methanol in microreactors.

Geophysical Prospecting, 2005

This work looks at the application of neural networks in geophysical well-logging problems and sp... more This work looks at the application of neural networks in geophysical well-logging problems and specifically their utilization for inversion of nuclear downhole data. Simulated neutron and γ-ray fluxes at a given detector location within a neutron logging tool were inverted to obtain formation properties such as porosity, salinity and oil/water saturation. To achieve this, the forward particle-radiation transport problem was first solved for different energy groups (47 neutron groups and 20 γ-ray groups) using the multigroup code EVENT. A neural network for each of the neutron and γ-ray energy groups was trained to reproduce the detector fluxes using the forward modelling results from 504 scenarios. The networks were subsequently tested on unseen data sets and the unseen input parameters (formation properties) were then predicted using a global search procedure. The results obtained are very encouraging with formation properties being predicted to within 10% average relative error. The examples presented show that neural networks can be applied successfully to nuclear well-logging problems. This enables the implementation of a fast inversion procedure, yielding quick and reliable values for unknown subsurface properties such as porosity, salinity and oil saturation.

Reaction Chemistry and Engineering, 2018

The demand for energy is continuously increasing worldwide. This places a constant strain on the ... more The demand for energy is continuously increasing worldwide. This places a constant strain on the production and availability of fossil fuels which most current energy is based on. Thus, alternative sources of energy (non-fossil based) are urgently needed to produce liquid fuels. However, conventional technologies and reactors used for these alternative processes have been associated with mass and heat transfer, long reaction times and extreme temperatures and pressures. To address these limitations, microreactors have been developed and utilised over the past decade, and have been proven to increase product yields, reduce residence time and product selectivity when compared to conventional reactors. This paper provides an in-depth review of the liquid fuel production routes over the last decade, and highlights the advantages of microreactors that have been successfully employed to overcome some of the issues faced with conventional bulk reactors.

Journal of Applied Geophysics, May 1, 2000

Reaction Chemistry and Engineering, 2020

A Computational Fluid Dynamic (CFD) model was derived and validated, in order to, investigate the... more A Computational Fluid Dynamic (CFD) model was derived and validated, in order to, investigate the hydrodeoxygenation 9 reaction of 4-propylguaiacol, which is a lignin-derived compound present in bio-oil. A 2-D packed bed microreactor was 10 simulated using pre-sulphided NiMo/Al2O3 solid catalyst in isothermal operation. A pseudo-homogeneous model was first 11 created to validate the experimental results from literature. Various operational parameters were investigated and validated 12 with the experimental data, such as temperature, pressure and liquid flow rate; and it was found that the CFD findings were 13 in very good agreement with the results from literature. The model was then upgraded to that of a detailed multiphase 14 configuration; and phenomena such as internal and external mass transfer limitations were investigated, as well as, reactant 15 concentrations on the rate of 4-propylguaiacol. Both models agreed with the experimental data, and therefore confirm their 16 ability for applications related to the prediction of the behaviour of bio-oil compounds hydrodeoxygenation. 17 33 obtained which has a heating value of approximately half of that 34 of conventional fuel oil averaging at about 30 MJ kg-1 4. Biomass 35 derived bio-oil has several disadvantages such as a low heating 36 value, high viscosity and a high oxygen content, which all restrict 37 its application as a liquid fuel. Therefore, further upgrading of 38 bio-oil by hydrodeoxygenation (HDO) is required 5. 39 40 The HDO process converts the oxygen containing compounds 41 such as acids, aldehydes, alcohols and phenol to oxygen-free 42 hydrocarbon fuels 6. Bio-oil obtained from the fast pyrolysis of 43 lignin contains approximately 39% of guaiacol and its 44 derivatives. Amongst these constituents, guaiacol is often 45 regarded as a representative model for bio-oil derived from 46 lignin because it has two types of CO bonds (Csp2OH and 47 65 phenolic compounds in the bio-oil is the origin of 66 polymerisation and coke formation during HDO at elevated 67 temperatures greater than 300 o C 3. 68 69 Lee et al. 8 studied the HDO of a model compound of lignin-70 derived bio-oil (guaiacol) because of its high potential to be 71 used as a substitute for conventional fuels. Platinum-loaded HY 72 zeolites (Pt/HY) with varying Si/AL molar ratios were used as 73 catalysts for the HDO of guaiacol, anisole, veratrole and phenol 74

Fuels, Jul 16, 2021

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Buildings, Jul 10, 2020

The motivation for this work stems from the increased number of high-rise buildings/ skyscrapers ... more The motivation for this work stems from the increased number of high-rise buildings/ skyscrapers all over the world, and in London, UK, and hence the necessity to see their effect on the local environment. We concentrate on the mean velocities, Reynolds stresses, turbulent kinetic energies (TKEs) and tracer concentrations. We look at their variations with height at two main locations within the building area, and downstream the buildings. The pollution source is placed at the top of the central building, representing an emission from a Combined Heat and Power (CHP) plant. We see how a tall building may have a positive effect at the lower levels, but a negative one at the higher levels in terms of pollution levels. Mean velocities at the higher levels (over 60 m in real life) are reduced at both locations (within the building area and downstream it), whilst Reynolds stresses and TKEs increase. However, despite the observed enhanced turbulence at the higher levels, mean concentrations increase, indicating that the mean flow has a greater influence on the dispersion. At the lower levels (Z < 60 m), the presence of a tall building enhanced dispersion (hence lower concentrations) for many of the configurations.

Atmospheric Environment, Oct 1, 2019

Traffic induced flow within urban areas can have a significant effect on pollution dispersion, pa... more Traffic induced flow within urban areas can have a significant effect on pollution dispersion, particularly for traffic emissions. Traffic movement results in increased turbulence within the street and the dispersion of pollutants by vehicles as they move through the street. In order to accurately model urban air quality and perform meaningful exposure analysis at the microscale, these effects cannot be ignored. In this paper we introduce a method to simulate traffic induced dispersion at high resolution. The computational fluid dynamics software, Fluidity, is used to model the moving vehicles through a domain consisting of an idealized intersection. A multi-fluid method is used where vehicles are represented as a second fluid which displaces the air as it moves through the domain. The vehicle model is coupled with an instantaneous emissions model which calculates the emission rate of each vehicle at each time step. A comparison is made with a second Fluidity model which simulates the traffic emissions as a line source and does not include moving vehicles. The method is used to demonstrate how the effect of moving vehicles can have a significant effect on street level concentration fields and how large vehicles such as buses can also cause acute high concentration events at the roadside which can contribute significantly to overall exposure.

Archives in chemical research, Mar 25, 2019

We present work associated with the implementation of a validated street-canyon/neighbourhood mod... more We present work associated with the implementation of a validated street-canyon/neighbourhood model that can help assess the air quality within existing building and neighbourhood designs and suggest modifications & improvements in order to produce sustainable, safer, healthier, and more comfortable urban environments. The work was motivated by both the increasing number of tall buildings in central London (“skyscrapers”) and also the recent plans of placing combined heat and power plants (CHPs) within the urban environment. The Large Eddy Simulation (LES) work was initiated after a series of wind tunnel experiments were carried out at the Enflo wind tunnel (University of Surrey) in order to assess the effect of emissions from Combined and Heat Power plants (CHPs) on top of one of the buildings. A series of scenarios were tested in the wind tunnel and mean concentrations and their fluctuations were measured. The LES models were set-up representing the wind tunnel geometries as well as wind conditions. The novel LES methodology implemented uses an unstructured, adaptive mesh and an anisotropic eddy viscosity tensor for the subgrid scales (based on the anisotropic mesh). The comparisons of the complex turbulent air flows and concentrations between model results and wind tunnel data show a good correlation – less than 20% error between predictions and measured data. We also looked at the effect of tall buildings on the surrounding complex air flows and dispersion of pollutants, using as prime examples the “Walkie-Talkie” building and the Shard skyscraper in central London, UK. Interesting simulation air flow results and dispersion for the “Walkie-Talkie” building are presented. Key words: air pollution, urban environment, wind tunnel experiments.

Numerous studies have been reported in the literature showing the applicability and limitations o... more Numerous studies have been reported in the literature showing the applicability and limitations of geophysical methods in different environmental problems. Mary such problems are associated with groundwater pollution, and what is also becoming increasingly important is the determination of aquifer properties such as hydraulic conductivity from the measured geophysical parameters. This is beneficial to the hydrogeologist because hydraulic conductivity values are needed in predictive groundwater modelling.