Esat Alpay

Professor Esat Alpay


Associate Dean (Education)
+44 (0)1483 686555
06 BB 04
Jane Phillips
01483 684503

Biography

Biography

Esat Alpay is Associate Dean (Education) in the Faculty of Engineering and Physical Sciences. He received his BSc (Hons) degree in Chemical Engineering from the University of Surrey, and his PhD from the University of Cambridge. He also holds an MA degree in the Psychology of Education (with distinction) from the Institute of Education (UCL).

He has wide interests in the educational support and skills development of undergraduate and postgraduate students. In his previous role at Imperial College London, he was responsible for supporting, developing and leading various teaching initiatives across the Faculty of Engineering. This included ethics education in several engineering departments, the training of Graduate Teaching Assistants and overseeing the teacher training procedures and requirements of Probationary Lecturers in the Faculty of Engineering. Some of his current educational interests include: the development and evaluation of student transferable skills, peer-based learning, formative assessment practices and the use of gamification and virtual (immersion) reality in Engineering Education. He has also been active in promoting scholarship in Engineering Education practice, specifically with contributions to and support of the emerging discipline of Engineering Education Research, including his role as Associate Editor of the European Journal of Engineering Education.

His scientific research activities have included studies in adsorption processes (pressure and thermal swing), hybrid reactors and polymer reaction engineering. This has included the modelling and optimisation of cyclic adsorption and reaction processes, adsorbent and catalyst characterisation and the set up of pilot scale adsorption units and static-mixer based reactors for viscous polymer processing.

Esat has been the recipient of several national and institutional teaching awards including the Times Higher Award for the course Research Skills Development for early-career researchers (2006), and the HEA Teaching Award for his work on Engineering Ethics (2011), the University of Surrey Learning and Teaching Award (2016) and most recently the Vice Chancellor's Award for Teaching Excellence (2016).

Research interests

Engineering Education: transferable skills development and evaluation; peer-based learning; formative assessment; gamification and virtual reality (augmented and immersion).

Teaching

University of Surrey:

  • Advanced Chemical Reaction Engineering (current)
  • Chemical Thermodynamics (current)
  • Engineering Dynamics (current)
  • Transfer Processes: Mass Transfer
  • Tutor on the final year design projects
  • Research Methods in Chemical Engineering and Coordinator of the MEng Research Projects
  • Tutor on the MEng Multidisciplinary Design Project

Imperial College London:

  • Introductory and Advanced Reaction Engineering
  • Polymerisation Processes
  • Engineering Ethics (4 departments)
  • Psychology for the Engineer
  • Business for Engineers
  • Tutor: Thermodynamics; Introductory Electrical Engineering; Final-Year Design Projects
  • Laboratory supervisor: Heat Transfer, Chemical Thermodynamics and Reaction Engineering themes
  • Workshops / courses: Teaching Skills for Graduate Teaching Assessments; Research Skills Devlopment; Advanced Presentation Skills; Career Planning and Leadership Development; Stress Management

Affiliations

  • Associate Editor, European Journal of Engineering Education
  • Fellow and Associate of the HEA (Higher Education Academy); Member of the HEA Engineering Education Research Special Interest Group
  • Coordinator and Principal Tutor on the PhD transferable skills programme for the Research Institutes of the Helmholtz Association, Germany
  • Corporate Member of the Institute of Chemical Engineers; i.e. a Chartered Engineer
  • Graduate Member of the British Psychological Society; i.e. Graduate Basis of Registry

Awards and Distinctions

Undergraduate (University of Surrey, 1988)• T.K. Ross Prize: highest overall examination performance• BOC / Dr. Schuftan Memorial Prize: best final year design project• IChemE. Book Prize: best industrial year performance (Wellcome Foundation Ltd.)

Postgraduate (University of Cambridge, 1992)• Danckwerts-Pergamon Prize 1992; see Chem. Eng. Sci, 1993, 48(iii)

Academic and Professional• Imperial College Award in Teaching Excellence, June 2000:Awarded for the teaching quality of the Reaction Engineering courses, and the introduction of a novel training programme for Graduate Teaching Assistants.

• Times Higher Award for Outstanding Support of Early-Career Researchers, 2006: Awarded for the development and implementation of the residential course on Research Skills Development.

• Best Paper winner:"Cross-departmental initiatives for a global dimension in engineering education", E. Alpay, A.L. Ahearn, A.M.J. Bull, 3rd International Symposium for Engineering Education, University College Cork, 2010.

• Best Paper shortlist:(i) “Changing the marks based culture of learning through peer assisted tutorials”, Alpay et al., American Society of Engineering Education (ASEE) Annual Conference, Austin, Texas, 2009.(ii) “Student-led podcasting for engineering education”, E. Alpay and S. Gulati, European Society for Engineering Education (SEFI) Annual Conference, Rotterdam, 2009.

• Higher Education Academy (HEA) Teaching Award 2011:Awarded for the teaching of Engineering Ethics; see: http://www.engsc.ac.uk/teaching-awards/2011.

• University of Surrey Learning and Teaching Award, 2016.

• Vice-Chancellor's Award for Teaching Excellence (University of Surrey), 2016

Invited Lectures and Presentations

  • Assessment of Higher Education Learning Outcomes (AHELO) - International Workshop for Enhancement of Higher Education Quality, Tokyo Institute of Technology, Sept 28-29 2010. Presentation title: "Engineering Education Developments Through the EnVision Project".
  • Preparing for Social Responsibility - International Workshop, Delft Technical University, Oct 13-15 2010. Presentation title: "Student-inspired activities for the teaching and learning of engineering ethics at Imperial College".
  • 4th Annual Teachers Conference - Teaching the Foundations of Clinical Practice, Cumberland Lodge, Windsor, March 25 2010. Presentation title: "Teamwork Skills Development in Engineering Education".
  • University of Birmingham (School of Electronic, Electrical and Computer Engineering) - July 8 2011. Presentation title: "Ethics Education in Engineering".
  • University of Exeter - September 2011. Presentation title: “A Global Dimension in Engineering Education”.
  • 20th International Congress on Chemical and Process Engineering (CHISA 20112), Prague, Czech Republic, Aug 25-29 2012. Keynote lecture: "Student engagement in engineering ethics".

My publications

Publications

N Arena, Esat Alpay, Norman Kirkby, Jacquetta Lee, R Clift (2017)An on demand chilling system: Activated carbon based desorptive cooling, In: Journal of Cleaner Production176pp. 937-945 Elsevier
Every year in Europe refrigerant gases with a greenhouse-warming equivalent of more than 30 Mt CO2 are emitted from retail refrigerators. Furthermore, the effective efficiency of such refrigerators is far below that achievable under ideal (e.g. optimal-load; minimum access) operation. In this work the design of an alternative on-demand cooling unit is presented. The unit is based on the cooling effect provided by desorption of carbon dioxide previously adsorbed onto a bed of graphite-bonded activated carbon: in this paper, a case study of a self-chilling beverage can is used to demonstrate the technology. The high compaction of the activated carbon, and the presence of graphite, enhances the heat transfer properties of the adsorbent, thus enhancing the efficiency of cooling. Furthermore, potential exists for the use of activated carbon and CO2 from waste sources. This paper provides an overview of the design basis and environmental advantages of the unit, and experimental and simulation studies on the thermal dynamics of the cooling process. Particular attention is given to the effective thermal conductivity of the activated carbon bed. The results indicate that adequate on-demand cooling can be achieved within a portable unit. However, scope exists for enhancing the heat transfer within the cooling chamber through design and bed composition alterations. Recommendations for improved unit design are presented.
The chill-on-demand system is a technology designed to provide cooled products on demand, thereby avoiding any requirement for chilled storage. It uses the cooling effect provided by the endothermic desorption of carbon dioxide previously adsorbed onto a bed of activated carbon contained in an inner component of the self-chilling product. This has the potential to be applied to any type of product that needs to be cold at the point of consumption. The principles of life cycle engineering have been utilized to evaluate the overall environmental performance of one possible application of this technology: a self-chilling beverage can, with a steel outer can to contain the beverage and an inner aluminium can to contain the adsorbent. The primary aim of this research is to devise a way to ensure that the self-chilling can supplies the best cooling performance with minimal global environmental impact. First, the adsorption/desorption process as a means of cooling was investigated, together with its application to the specific case of carbon dioxide adsorbed on a bed of activated carbon obtained from coconut shells. A specific experimental activity was designed and supported by the implementation of a transient heat exchange model. Next, the potential environmental impacts of the product were evaluated by using a Life Cycle Assessment tool. The analysis considered all the life cycle stages of a self-chilling can: from the manufacture of each part of the beverage container, to its utilization and end-of-life management. The results, compared with those of a conventional beverage can, highlight the importance of using activated carbon derived from biomass and locating its production in countries with a low carbon-intensity electricity supply. More substantial environmental and technical improvements would depend on finding adsorbents with much larger capacity, and developing a system with very high rates of recovery and re-use.
Saleh O Alaswad, Sami Al-aibi, Esat Alpay, Adel Sharif (2018)Efficiency of Organic Draw Solutions in a Forward Osmosis Process Using Nano-filtration Flat Sheet Membrane, In: Journal of Chemical Engineering & Process Technology9(1) OMICS International
The aim of this study is to investigate the performance of specific organic osmotic agents, namely, Sucrose draw solution and Glucose draw solution against deionized water in a Forward Osmosis (FO) process using NF flat sheet membrane. The key parameters affecting the FO process studied were: temperature, flow rates of osmotic agent and feed water, and concentration of osmotic agent. The experimental results showed that increasing the concentration of osmotic agents yield lower water flux, recovery percentage and permeability, along with an apparent increase in the specific energy consumption. Although the findings indicated superior performance of Glucose over Sucrose as a better osmotic agent, it has to be emphasized that both organics were ineffective draw solutions against deionized water for the Nano-filtration (TFC-SR2) membrane used in this study and the given operating parameters.
In the present work, for the first time, an experimental and theoretical study of the heat transfer characteristics of a bubble type three-phase direct contact condenser has been carried out. The experiments were conducted using a Perspex column of 70 cm in total height and 4 cm inner diameter, as a direct contact condenser. The active column height throughout the experiments was 48 cm. Pentane vapour at three different initial temperatures (40℃, 43.5℃ and 47.5℃), was used as the dispersed phase while tap water at a constant temperature (19℃) was used as the continuous phase. Seven different dispersed phase mass flow rates and five different continuous phase mass flow rates were tested. The experiments considered the transient temperature distribution along the direct contact condenser, the steady-state temperature distribution, the volumetric heat transfer coefficient, the heat transfer rate per unit volume and the holdup ratio. Also, the efficiency and capital cost of the direct contact condenser were estimated, and the heat transfer of the three-phase direct contact condenser during flooding was studied. Theoretical models describing the direct contact condenser were developed. These models included the transient temperature distribution, the steady-state temperature distribution and the volumetric heat transfer coefficient. These models implicitly involved new derivations for the surface heat transfer coefficient, the two-phase bubble size, the relative velocity of two-phase bubbles, the drag coefficient and the added mass of the two-phase bubble. All expressions were derived analytically except for the transient temperature distribution along the condenser which was found numerically, using MATLAB. The results showed that the mass flow rate ratio has a significant effect on the heat transfer characteristics of the condenser, while the initial temperature of the dispersed phase has only a slight effect. The models developed were fitted the experimental data well.
One of the main objectives of a firm is to add value to the firm and to earn more profit; therefore, the financial performance of a firm in a supply chain has to be managed and modelled properly. The aim of this thesis is to devise a payment strategy to improve the financial performance of a firm in a supply chain through evaluating the effects of the supply chain operation including demand variation, delivery time, customer satisfaction and horizontal and vertical integration on the financial performance of the firm. In fact, it aims to develop an optimisation mathematical model to maximise the aggregated cash flow of a firm within a time horizon through prioritising the cash outflow invoices and optimising the payment strategy parameters such as penalty rate and customer discount. To represent the cash flow of a firm as well as the movement of customers through the firm in different time periods, a cascade diagram is developed where the cash flow of a firm in each period is the summation of cash available from the previous period received from the satisfied customers plus the amount of cash received from the new customers minus the amount of cash which has to be paid to the upstream partners. Since the cash inflow of a firm in each time period is directly related to the number of satisfied customers in the previous period; therefore, the firm tries to ensure that the maximum number of satisfied customers are transferred to the next period in order to have the maximum amount of cash inflow in each period. In addition, the effects of demand variation and delivery time as a result of the supply chain operation, usually known as logistic bullwhip, on the financial performance of a firm in a supply chain are investigated in different time periods. In fact, the effects of the supply chain operation on the financial performance of a firm are formulated through introducing additional costs to the firm in each period. However, the cash outflow invoices in each period are scheduled and prioritised based on the available amount of cash in the firm and the penalty rate is applied to the customers who receive the invoices and suppose to pay the amount of invoices in each period on late payments, while the optimum penalty rate in each period is correlated to the amounts supposed to be received in the next periods and the penalty rate of the competitors. Additionally, the optimum customer discount can be applied to compensate the cost of customer dissatisfaction due to the late delivery of products to the customers. Also, horizontal and vertical integration between supply chain partners can improve the supply chain operation and, consequently the financial performance of a firm in a supply chain.
E Alpay, LS Kershenbaum, LS Kirkby The enhancement of catalytic dehydrogenation reactions through pressure swing reactor operations, In: Proceedings of the 14th Ibero-American Symposium on Catalysispp. 1269-?
Vasileios Katranidis, Sai Gu, Tomas Ramirez Reina, Esat Alpay, Bryan Allcock, Spyros Kamnis (2017)Experimental study of high velocity oxy-fuel sprayed WC-17Co coatings applied on complex geometries. Part B: Influence of kinematic spray parameters on microstructure, phase composition and decarburization of the coatings, In: Surface & Coatings Technology328pp. 499-512 Elsevier
The aim of this study is to evaluate comprehensively the effect of spray angle, spray distance and gun traverse speed on the microstructure and phase composition of HVOF sprayed WC-17 coatings. An experimental setup that enables the isolation of each one of the kinematic parameters and the systemic study of their interplay is employed. A mechanism of particle partition and WC-cluster rebounding at short distances and oblique spray angles is proposed. It is revealed that small angle inclinations benefit notably the WC distribution in the coatings sprayed at long stand-off distances. Gun traverse speed, affects the oxygen content in the coating via cumulative superficial oxide scales formed on the as-sprayed coating surface during deposition. Metallic W continuous rims are seen to engulf small splats, suggesting crystallization that occurred in-flight.
MA Kolade, A Kogelbauer, E Alpay (2009)Adsorptive reactor technology for VOC abatement, In: Chemical Engineering Science64(6)pp. 1167-1177
The use of the monolith as an adsorptive reactor (MAR) is proposed as a viable and novel alternative for VOC disposal. The MAR combines adsorptive separation and catalytic combustion of the VOC in a single reactor unit and is thought to make effective utilisation of energy due to efficient heat integration. Theoretical studies on the feasibility and application of the adsorptive reactor concept for VOC oxidation is presented in this paper. Thus unlike previous work, present studies focus on an exothermic reaction system and the ability of the MAR to control thermal runaway. A two dimensional mathematical model accounting for non isothermal adsorption and reaction, mass transfer limited adsorption kinetics and non linear (Tóth) adsorption equilibria, has been developed. The process is operated cyclically in two steps: adsorption and desorption/reaction. The VOC is fed into the reactor in the adsorption step and captured to produce a pure carrier gas effluent. Concentration and thermal swing is induced in the second step by means of an air feed. The most outstanding feature of the MAR is its ability to prevent thermal runaway whilst maintaining a high VOC conversion. Simulation results indicate that the careful selection of step times for adsorption and desorption, feed temperatures and inlet velocities lead to stability and energy requirements which outperform equivalent conventional designs. The MAR is thermally more stable due to the controlled release of the reactant from the adsorbed phase into the reaction zone, and also the heat integration of endothermic desorption and exothermic reaction. © 2008 Elsevier Ltd. All rights reserved.
S Fan, JHG Steinke, E Alpay (2005)Emulsion polymerizations in a pilot-scale loop reactor with inline static mixers, In: Industrial and Engineering Chemistry Research44(15)pp. 5483-5490
Emulsion polymerizations of methyl methacrylate were carried out in a pilot-scale tubular reactor configured in a batch-loop mode. The tubular sections of the reactor were fitted with in-line static mixers to incite low-shear mixing. The reactor was used to investigate the influence of different recipes and operating conditions on reaction, particularly on the monomer conversion and the polymer particle-size distribution. Experimental data were compared to equivalent bench-scale studies using a conventional stirred flask. A mathematical model was also developed for predicting the temperature dynamics and the conversion of methyl methacrylate polymerization in the pilot-scale reactor. Conversions and particle-size distributions of the pilot-scale loop reactor were found to be very similar to that of the bench-scale studies. The results indicate that in-line static mixers can help to maintain emulsion stability and provide a means for good temperature control, without unduly influencing polymer particle-size distribution. © 2005 American Chemical Society.
D Chatsiriwech, E Alpay, LS Kershenbaum, NF Kirkby The enhancement of catalytic reaction by pressure swing adsorption, In: Proceedings CHEMPOR'93pp. 67-74
J Sheikh, I Casasempere-Miralles, LS Kershenbaum, E Alpay Experimental investigations of butadiene hydrogenation in a rapid pressure swing reactor, In: Proceedings of the 1997 Jubilee Research Eventpp. 1033-1036
SP Gretton-Watson, E Alpay, JHG Steinke, JS Higgins (2005)Hyperbranched polymers. Synthesis, modeling, experimental validation, and rheology of hyperbranched poly(methyl methacrylate) derived from a multifunctional monomer (MFM) route, In: Industrial and Engineering Chemistry Research44(23)pp. 8682-8693
The synthesis of hyperbranched PMMA has been achieved using a facile one-step batch solution polymerization reaction. The reaction is essentially a linear polymerization doped with appropriate amounts of a multifunctional monomer (MFM) and chain transfer agent (CTA). On this basis, a theoretical model for the MFM reaction has been developed and experimentally validated for the number-aver age molecular weight and degree of branching data, by assuming isothermal batch conditions and employing key reaction parameters from established linear PMMA kinetics. A first comparison of the melt rheology of the hyperbranched polymer with that of the linear one revealed a significant reduction in melt viscosity and shear thinning. It is expected that the generic model developed here will guide the manufacture of other free-radical hyperbranched polymers, of desired architecture or physical properties, using modeling and optimization methods. © 2005 American Chemical Society.
SP Gretton-Watson, E Alpay, JHG Steinke, JS Higgins (2006)Multi-functional monomer derived hyperbranched poly(methyl methacrylate): Kinetic modelling and experimental validation, In: Chemical Engineering Science61(5)pp. 1421-1433
Multi-functional monomer induced hyperbranched PMMA production has been shown to be a relatively facile, one-step batch solution polymerisation reaction. Essentially, the reaction is a linear polymerisation doped with appropriate amounts of multi-functional monomer (MFM) and chain transfer agent (CTA). A theoretical model for the MFM reaction has been experimentally validated using conversion, number-average molecular weight, and branching data, by employing key reaction parameters from established linear PMMA kinetics. However, the kinetic model has been modified to account for the MFM and CTA contributions, which generate the branched architecture and inhibit the onset of gelation, respectively. An important outcome of this work is the development of a generic model for hyperbranched polymer synthesis, in which the manufacture of other free-radical hyperbranched polymers, of desired architecture or physical properties, can be guided using modelling and optimisation methods. © 2005 Elsevier Ltd. All rights reserved.
E Alpay, E Walsh (2007)Evaluating student skills and development: Current practice and the Imperial College experience, In: Skills Training in Research Degree Programmes: Politics and Practice Open University Press
E ALPAY, LS KERSHENBAUM, NF KIRKBY (1995)PRESSURE CORRECTION IN THE INTERPRETATION OF MICROREACTOR DATA, In: CHEMICAL ENGINEERING SCIENCE50(6)pp. 1063-1067 PERGAMON-ELSEVIER SCIENCE LTD
G Koumpouras, E Alpay, F Stepanek (2005)Theoretical studies on sorption-enhanced hydrogen production, In: AIChE Annual Meeting, Conference Proceedingspp. 10224-10231
Theoretical analysis of an alternative process for hydrogen production through steam methane reforming (SMR), based on the concept of adsorption-enhanced reaction, is presented. This approach can improve reactant conversion and establish a more favourable reaction equilibrium than that of a conventional reactor. As a result, relatively low operating temperatures are possible for a given conversion. In the proposed process, mobile (pneumatically conveyed) adsorbent particles are passed through a stationary SMR catalyst monolith. Adsorbent regeneration is carried out in an external regeneration unit, thus decoupling the reaction and adsorbent regeneration steps. Heat for reaction is also supplied via the regeneration unit (i.e. via the thermal capacitance of the adsorbent), and thus effective energy integration is possible between the reactor and regenerator units. A mathematical model accounting for non-isothermal reaction and adsorption, mass transfer limited adsorption kinetics and non-linear (Langmuirian) adsorption equilibria, has been developed. The performance of the adsorptive reactor in terms of conversion enhancement is presented in this paper. Simulation results indicate considerable reaction enhancement through the use of a flowing adsorbent medium. The importance of the correct selection of operating parameters on the process feasibility is also highlighted.
CP Hull, NF Kirkby, E Alpay, LS Kershenbaum An experimental investigation of catalytic reaction under pressure swing operation, In: Proceedings of the 1994 IChemE Research Eventpp. 562-?
GC Koumpouras, E Alpay, F Stepanek (2007)Mathematical modelling of low-temperature hydrogen production with in situ CO2 capture, In: Chemical Engineering Science62(10)pp. 2833-2841
Theoretical analysis of a process for low-temperature hydrogen production through steam methane reforming (SMR), based on the concept of adsorption-enhanced reaction, is presented. In the proposed process, mobile (pneumatically conveyed) adsorbent particles are passed through a stationary SMR catalyst monolith. Adsorbent regeneration is carried out in an external unit, thus decoupling the reaction and adsorbent regeneration steps, and allowing continuous operation. Heat for reaction is also supplied via the regeneration unit (via the thermal capacitance of the adsorbent), and thus effective energy integration is possible between the reactor and regenerator units. A mathematical model accounting for non-isothermal reaction and adsorption, mass transfer limited adsorption kinetics and non-linear (Langmuirian) adsorption equilibria, has been developed. The performance of the adsorptive reactor in terms of conversion enhancement is presented in this paper. Simulation results indicate considerable conversion enhancement through the use of a flowing adsorbent medium. The importance of the correct selection of operating parameters, i.e., adsorbent mass flow rate and temperature, on the process feasibility is also highlighted. © 2007 Elsevier Ltd. All rights reserved.
D Chatsiriwech, E Alpay, LS Kershenbaum, NF Kirkby Enhancement of catalytic reaction by pressure swing adsorption, In: Proceedings of the 11th International CHISA Congresspp. 351-366
G Koumpouras, E Alpay, F Stepanek (2006)A novel concept in adsorption-enhanced hydrogen production, In: AIChE Annual Meeting, Conference Proceedings
The development of alternative concepts for production of hydrogen via steam methane reforming (SMR) has been attractive due to the limitations associated with the performance of the conventional catalytic reactor. The flow of pneumatically conveyed CO2 adsorbent particles within a stationary SMR catalyst phase was proposed, with adsorbent regeneration performed in a separate unit. A significant degree of conversion enhancement (up to 75%) was shown at moderate temperatures (750 K). Simulations results pointed out the importance of the interaction between the reaction and regeneration stages of the process. A model-based optimization approach was adopted to identify the optimum process scheme in terms of energy utilization. Alternative process schemes and designs were compared. This is an abstract of a paper presented at the AIChE Annual Meeting (San Francisco, CA 11/12-17/2006).
E Alpay, AL Ahearn, RH Graham, AMJ Bull (2008)Student enthusiasm for engineering: Charting changes in student aspirations and motivation, In: European Journal of Engineering Education33(5-6)pp. 573-585
Many recent teaching initiatives in engineering education have the underlying premise of improving student engagement with global issues and providing first-hand experience of complex problems associated with sustainable development and production. A greater understanding of actual motivational drivers may help in student recruitment and retention, and address, e.g. gender disparity. In this work, student motivations and aspirations are explored through a cross-faculty survey of undergraduate engineering students. The results indicate that while many students start an engineering degree with an aspiration to 'invent something new' and 'make a difference to the world', these diminish with time to be dominated by issues such as financial security. Students who continue to aspire to the creative/high-impact notions of engineering also maintain an enthusiasm for engineering. However, all students desire more practical work and skills training. Based on these findings, some general recommendations are given for further inspiring students towards engineering.
E Alpay (2007)The polymorphic nature of the 5-HTT gene and depression [4], In: Psychologist20(6)pp. 349-?
E Alpay, E Walsh (2008)A Skills Perception Inventory for Evaluating Postgraduate Transferable Skills Development, In: Assessment & Evaluation in Higher Education33(6)pp. 581-598
This article reports on the development, application and results of a skills evaluation inventory which was specifically designed to provide quantitative feedback on the effects of a three-day residential training course attended by PhD students early in their research careers. The course was developed at Imperial College London, partly in response to the "Roberts" agenda, which has highlighted the importance of transferable skills to the future careers of researchers. The questionnaire aims to measure student perceptions of their skill levels in four key areas. In addition a scale was included to measure changes in their general attitudes towards the benefits or otherwise of training in transferable skills. The inventory was administered at the very beginning and end of the course. Statistical analysis was used to refine the inventory and as a result all five scales were found to have good reliability. The results showed that after attending the course there were statistically significant increases in the participants' perceived levels of skill in each area and a more positive attitude to skills development courses overall was demonstrated. Furthermore, differences in skill perceptions were observed depending on the gender and residential status of researchers. For example, female researchers were found to have generally lower levels of confidence than males, specifically for pre-course beliefs on group work and communications skills. A further benefit is that the findings have helped to win respect and support for continued investment in the residential course programme. (Contains 2 figures, 4 tables and 3 notes.)
GC Koumpouras, E Alpay, A Lapkin, Y Ding, F Štěpánek (2007)The effect of adsorbent characteristics on the performance of a continuous sorption-enhanced steam methane reforming process, In: Chemical Engineering Science62(18-20)pp. 5632-5637
The steam methane reforming (SMR) process for hydrogen production with in situ CO2 capture on adsorbent particles pneumatically conveyed through a monolithic catalytic reactor and subsequently regenerated ex situ, was considered. A mathematical model has been formulated, based on differential mass and energy balances in the reactor and the regenerator, Langmuir isotherm for CO2 sorption equilibrium, the linear driving force approximation for sorption kinetics, and literature values for the kinetics of the three main SMR reactions. The effect of the adsorbent characteristics-the maximum CO2 capacity and the sorption kinetics-on the overall process performance in terms of methane conversion and CO2 separation has been systematically investigated in a parametric study. The main conclusions of the study are that: (i) conversion enhancement and CO2 recovery show a strongly non-linear dependence on both sorption capacity and kinetics; (ii) comparable conversion enhancement and CO2 recovery can be achieved by means of both lithium zirconite-like (high capacity, slow kinetics) and hydrotalcite-like (low capacity, fast kinetics) adsorbents; (iii) if an ideal adsorbent possessing hydrotalcite-like sorption kinetics and zirconite-like capacity were developed, the conversion enhancement factor could be more than doubled and a nearly 100% CO2 recovery could be achieved under otherwise identical conditions. © 2007 Elsevier Ltd. All rights reserved.
E Alpay, AL Ahearn, RH Graham, AMJ Bull Inspiring the next generation of engineers: student perspectives of engineering education, In: Proceedings of ICEE2008
E Alpay, A Hari, M Kambouri, AL Ahearn Gender issues in the research environment, SEFI Annual Conference 2009, In: Proceedings of the 37th SEFI Conferencepp. 78-?
E Alpay, SD Masouros The design of a computer-based maths toolbox for engineering students, In: Proceedings of the 37th SEFI Conferencepp. 147-?
E Alpay, AL Ahearn, FO OyeLeye, AMJ Bull The impact of extra-curricular activities on the development and motivation of engineering students, In: Proceedings of the 37th IGIP Symposium
Y Ding, E Alpay (2000)Adsorption-enhanced steam-methane reforming, In: Chemical Engineering Science55(18)pp. 3929-3940
Experimental and theoretical studies of steam-methane reforming in the presence of a hydrotalcite-based CO2 adsorbent are presented. Attention is given to the analysis of the transient behaviour of a tubular (integral) reactor when an Ni-based catalyst is admixed with the adsorbent. Considerable enhancement of the methane conversion is experimentally demonstrated. Enhancement arises from the favourable shifts in the reaction equilibria of the reforming and water-gas shift reactions towards further CO2 production. As predicted, the potential for conversion enhancement is shown to increase under the conditions of a high reactor space time, high operating pressure, or a low steam-to-methane feed ratio, i.e. when reaction equilibrium limitations are important. A mathematical model, accounting for mass transfer limited adsorption kinetics, non-linear (Langmuirian) adsorption equilibria and a general reaction kinetic model, is shown to accurately predict the observed elution profiles from the reactor, and thus the degree of conversion enhancement. (C) 2000 Elsevier Science Ltd. All rights reserved.
E Alpay, D Chatsiriwech, LS Kershenbaum, CP Hull, NF Kirkby (1994)Combined reaction and separation in pressure swing processes, In: CHEMICAL ENGINEERING SCIENCE49(24B)pp. 5845-5864 PERGAMON-ELSEVIER SCIENCE LTD
E Alpay, N Haq, LS Kershenbaum, NF Kirkby (1996)Adsorption parameters for strongly adsorbed hydrocarbon vapours on some commercial adsorbents, In: GAS SEPARATION & PURIFICATION10(1)pp. 25-33 BUTTERWORTH-HEINEMANN LTD
CP HULL, NF KIRKBY, E ALPAY, D CHATSIRIWECH, LS KERSHENBAUM (1994)AN EXPERIMENTAL INVESTIGATION OF CATALYTIC REACTION UNDER PRESSURE SWING OPERATION, In: 1994 ICHEME RESEARCH EVENT, VOLS 1 AND 2pp. 562-564
G Koumpouras, E Alpay (2005)A structured reactor approach to sorption-enhanced hydrogen production, In: 7th World Congress of Chemical Engineering, GLASGOW2005, incorporating the 5th European Congress of Chemical Engineeringpp. 126-?
An alternative process for hydrogen production through steam methane reforming (SMR), based on the concept of adsorption-enhanced reaction, is studied. The newly proposed process consists of a reactor/adsorber unit and regeneration (desorption) unit. The novelty of this approach is the use of a stationary SMR catalyst phase, through which adsorbent flows for the in-situ and selective removal of CO 2. Adsorbent regeneration is carried out ex-situ, and hot regenerated adsorbent passed back to the reactor unit. A mathematical model, accounting for general reaction kinetics, mass transfer limited adsorption kinetics, and non-linear (Langmuirian) adsorption equilibria, is developed. Packed bed and monolith catalyst structures are considered, and appropriate particle and gas flow models through such structures are evaluated. The feasibility of new adsorbent and catalyst materials currently being developed are evaluated. The results of the theoretical evaluation of this new reactor concept are presented. This is an abstract of a paper presented at the 7th World Congress of Chemical Engineering (Glasgow, Scotland 7/10-14/2005).
E Alpay, Y Ding (2000)Equilibria and kinetics of CO2 adsorption on hydrotalcite adsorbent, In: Chemical Engineering Science55(17)pp. 3461-3474
Experimental data for the adsorption and desorption of CO2 on potassium promoted hydrotalcite adsorbent were measured under conditions depicting the separation enhanced steam-methane reforming process. Adsorption saturation capacities of 0.58 and 0.65 mol/kg were measured at 753 and 673 K, respectively, under wet feed conditions. An ~ 10% reduction of the saturation capacity was observed under dry feed conditions. In both cases, a Langmuir model adequately described the adsorption isotherm. Experimental data revealed the rapid degradation of the adsorbent under dry feed conditions, and higher losses at higher temperatures. Adsorbent regeneration was possible by means of a steam purge, but some irreversible loss in capacity was indicated for very long times-on-stream. A dynamic model accounting for semi-technical scale operation was developed to describe the key operating steps of the pressure swing based adsorptive process. Kinetic studies suggested mass transfer control for the adsorption, depressurization, and purge steps of operation. The study illustrated the complexities of CO2 adsorption on hydrotalcite. Some variation in adsorption parameters is expected depending on the conditions of pre-treatment. For adsorbent previously not contacted with steam or CO2 feed, observations indicated an initial strong adsorption of material, depicting a chemisorption mechanism.
YS Cheng, E Alpay, LS Kershenbaum (1998)Simulation and optimisation of a rapid pressure swing reactor, In: Computers and Chemical Engineering22(SUPPL.)
A rapid pressure swing reactor, which conducts reaction and adsorption/desorption simultaneously and is operated in a periodic pressure variation mode, is investigated through computer simulation and optimisation. A general mathematical model which takes account of the dynamic variation and spatial distribution of properties within the bed has been formulated and described by a set of partial differential and algebraic equations. Both the successive substitution and simultaneous discretisation approaches have been used for determining cyclic steady state. The method of orthogonal collocation on finite elements is employed for the discretisation of both the spatial and temporal domains. Simulation experience indicates that the simultaneous discretisation approach is much more robust and efficient when compared to the successive substitution approach. The optimisation of the rapid pressure swing reactor is studied via the simultaneous discretisation approach. A significant improvement over the equilibrium yield is shown by the optimisation results for a reversible dissociation reaction. © 1998 Elsevier Science Ltd. All rights reserved.
E Alpay, PS Cutler, S Eisenbach, AJ Field Changing the marks based culture of learning through peer assisted tutorials, In: Proceedings of the 2009 ASEE Annual Conference,
I Yongsunthon, E Alpay (1998)Design and optimisation of temperature cycled adsorptive reactors, In: Computers and Chemical Engineering22(SUPPL.)
This work describes a novel process in which reaction, separation and heat-exchange are combined within a single unit operation. Thermal and concentration swing steps are considered in the theoretical design and optimisation of the process configurations, and include co- and counter-current configurations. The operation is carried out over a fixed bed of an admixture of catalyst and adsorbent which selectively removes the primary product from the reaction zone. The adsorbent is periodically regenerated using hot inert gas, which also acts as an energy supply step for the endothermic reaction. An optimisation strategy is used to seek the optimal operating policy that enables the process to separate the primary product, and outperform an optimal PFR in terms of production yield and energy consumption. © 1998 Published by Elsevier Science Ltd. All rights reserved.
E Alpay, S Gulati Student-led podcasting for engineering education, In: Proceedings of the 37th SEFI Conferencepp. 106-?
I Yongsunthon, E Alpay (1999)Design of periodic adsorptive reactors for the optimal integration of reaction, separation and heat exchange, In: Chemical Engineering Science54(13-14)pp. 2647-2657
Optimisation techniques are used for the design of novel forced-periodic reactors in which there is the integration of catalytic reaction, adsorptive separation and direct fluid to solid heat exchange within a single unit operation. For such configurations, dynamic operation is utilised to generate favourable temperature (catalyst activity) profiles, and, through in situ separation, to provide reaction enhancement and the enriched recovery of the primary product(s). The work thus involves aspects of thermal and concentration swing adsorption, reverse (or bidirectional) flow reactor operation, and thermal regeneration. The design methodology is based on fully discretised mathematical models, upon which periodic constraints are imposed to yield direct cyclic steady state solutions. The models are then formulated as non-linear programming problems to yield optimal operating schedules and conditions. Models are developed for general endothermic and equilibrium limited reaction schemes; as a case study, specific consideration is given to the dehydrogenation of methylcyclohexane to toluene over and admixture of Pt-Al2O3 catalyst and zeolite 5A adsorbent. When compared to an equivalent and optimally operated adiabatic plug flow reactor, design and operating conditions are calculated for both single and multistage configurations in which there are significant improvements in reactant conversion, with the additional benefit of the bulk separation of the product species. These qualities of the hybrid reactors are attained for energy inputs (i.e. feed pre-heat requirements) which do not exceed that of the equivalent steady flow reactor. The results also predict larger improvements in reactor performance when there is greater flexibility in the way in which heat and material are introduced into the reactor systems. For example, for a five-stage configuration involving mixed series-parallel connections of the stages, and the disproportional splitting of feed streams to each stage, a conversion of 59% is calculated for the production of 0.02 mol/m2 s toluene (cf. 23% for an equivalent reactor), with 72% recovery of the toluene in a near pure form (inert-free basis).
D CHATSIRIWECH, E ALPAY, LS KERSHENBAUM, CP HULL, NF KIRKBY (1994)ENHANCEMENT OF CATALYTIC REACTION BY PRESSURE SWING ADSORPTION, In: CATALYSIS TODAY20(3)pp. 351-366
Vasileios Katranidis, Sai Gu, Tomas Ramirez Reina, Esat Alpay, B Allcock, S Kamnis (2017)Experimental study of high velocity oxy-fuel sprayed WC-17Co coatings applied on complex geometries. Part B: Influence of kinematic spray parameters on microstructure, phase composition and decarburization of the coatings, In: Surface and Coatings Technology328pp. 499-512 Elsevier
The aim of this study is to evaluate comprehensively the effect of spray angle, spray distance and gun traverse speed on the microstructure and phase composition of HVOF sprayed WC-17 coatings. An experimental setup that enables the isolation of each one of the kinematic parameters and the systemic study of their interplay is employed. A mechanism of particle partition and WC-cluster rebounding at short distances and oblique spray angles is proposed. It is revealed that small angle inclinations benefit notably the WC distribution in the coatings sprayed at long stand-off distances. Gun traverse speed, affects the oxygen content in the coating via cumulative superficial oxide scales formed on the as-sprayed coating surface during deposition. Metallic W continuous rims are seen to engulf small splats, suggesting crystallization that occurred in-flight.
E Alpay (2011)Wish i wasn't here?, In: Psychologist24(9)pp. 626-627
E Alpay, CN Kenney, DM Scott (1993)Simulation of rapid pressure swing adsorption and reaction processes, In: Chemical Engineering Science48(18)pp. 3173-3186
A general model for non-isothermal adsorption and reaction in a rapid pressure swing process is described. Several numerical discretisation methods for the solution of the model are compared. These include the methods of orthogonal collocation, orthogonal collocation on finite elements, double orthogonal collocation on finite elements, and cells-in-series. Computationally, orthogonal collocation on finite elements is found to be the most efficient of these. The model is applied to air separation for oxygen production. Calculations confirm the formation of a concentration shock when an adsorbent bed is pressurised with air. The form and propagation of the shock over short times is found to be in excellent agreement with the exact similarity transformation solutions derived for an infinitely long bed. For air separation, novel experimental measurements, showing an optimum particle size for maximum product oxygen purity, are accurately described by the model. Calculations indicate that a poor separation results from ineffective pressure swing for beds containing very small particles, and from intraparticle diffusional limitations for beds containing very large particles. For adsorption coupled with reaction, finite rate and reversible reactions are considered. These include both competitive and non-competitive reaction schemes. For the test case of a dilute reaction A &.rlhar2; B + 3C, with B the only adsorbing species, bed pressurisation calculations are found to be in excellent agreement with the solutions obtained by the method of characteristics. © 1993.
E Alpay (2013)Peer-feedback and the paradox of knowing, In: Psychologist26(9)
E de Graaff, E Alpay, J Bernhard, S Ihsen, A Kolmos (2012)Editorial, In: European Journal of Engineering Education37(1)pp. 1-2
E Alpay, AL Ahearn, RH Graham, AMJ Bull Engineering Education Developments through EnVision, In: Proceedings of the 7th ASEE Global Colloquium on Engineering Education
M Holloway, E Alpay, A Bull (2010)A quantitative approach to identifying threshold concepts in engineering education, In: Engineering Education 2010: Inspiring the Next Generation of Engineers, EE 2010
Research by Meyer and Land (2003) introduced the notion of 'Threshold Concepts' - concepts that students initially find troublesome, but which, when understood, transform and integrate ways of thinking about their respective discipline. The identification of threshold concepts in engineering may help guide the design of core courses and the approaches used in teaching mastery components. However, the identification of such concepts has proved rather troublesome in itself, with ongoing debate as to value of the construct in real teaching contexts. This study uses frequent student survey to look for the characteristics which may be indicative of threshold concepts; attention is given to some key first year undergraduate-level engineering concepts. A question-set is developed, and electronic handheld voting devices used to regularly quantify the student self-perception of understanding, which is further compared with a test of actual understanding. In addition, a retrospective survey and interview are used together with chronological record of students' self-perceptions and test results to identify transforming instants. Finally, a favourable set of survey questions is proposed for identifying the defining characteristics of potential threshold concepts. © 2009 M. Holloway, E. Alpay, A. Bull.
I Yongsunthon, E Alpay (1998)Conversion-temperature trajectories for well-mixed adsorptive reactors, In: Chemical Engineering Science53(4)pp. 691-696
Reactant conversion parameters which account for the solid- and fluid-phase distribution of adsorbate are used to yield information on the conversion-temperature characteristics of well-mixed and adiabatic adsorptive reactors. When applied to endothermic reactions in which there is the preferential adsorption of product species, favourable operating trajectories in the conversion-temperature plane are generated for both batch and steady flow type operation. The effect is attributed to a reduction in the net heat of consumption under the conditions of simultaneous adsorption and reaction; modified (effective) heats of reaction are derived to characterise this effect. Conditions for mean-isothermal reactor operation under adiabatic conditions are also derived, and shown to be functions of the heats of adsorption and reaction, and the capacity of the adsorbent for the various reaction species. For the flow reactor, the analysis is extended to mass-transfer-limited adsorption as described by a linear driving force model. Conversion-temperature trajectories are thus attained which account for the adsorption and reaction parameters, and the residence time of the adsorbent in the reactor. As an example of the potential reduction in the net heat of reaction, the dehydrogenation of methylcyclohexane to toluene in an adiabatic flow reactor, and in the presence of various commercial adsorbents, is considered.
S Fan, E Alpay (2004)Calorimetric estimation for a batch-loop emulsion polymerisation reactor, In: Chemical Engineering Science59(13)pp. 2811-2815
To facilitate the online monitoring and control of a pilot-scale polymerisation reactor, state estimation techniques are investigated. Specifically, a batch-loop reactor is employed for the emulsion polymerisation of methyl methacrylate. The reactor consists of jacketed tubular sections fitted with in-line static mixers, thus providing mixing homogeneity and improved temperature control. A direct estimation of the reaction rate is attained through measurements of process and jacket side temperatures, and thus a calorimetric method of estimation. This is compared with a Kalman filter based calorimetric approach, in which there is compensation for model uncertainties and measurement noise. For both estimation methods, no knowledge of the kinetic model for polymerisation is needed. Experimental results indicate that with an accurate model of the process energy balance, in which, for example, the recycle pump energy input is described, the Kalman filter approach is found to provide excellent prediction of conversion, for both high and low conversions, for this pilot-plant reactor system. The approach does not require any (approximate) kinetic knowledge, and is thus considerably easier in implementation than the extended Kalman filter approaches. © 2004 Elsevier Ltd. All rights reserved.
J Sheikh, LS Kershenbaum, E Alpay (1998)Analytical basis for separation enhanced reaction in continuous flow processes, In: Chemical Engineering Science53(16)pp. 2933-2939
Modified conversion and reaction extent parameters are used to investigate the effect of simultaneous reaction and adsorption in a well-mixed, steady-state, continuous flow reactor. The analytical method generates conditions in which reactant conversion, product yield or product selectivity exceed that of an equivalent adsorbent-free system. The conditions are shown to be functions of effective reaction Damkohler numbers and the adsorption parameters of the various reaction species. The method is specifically applied to the linear reaction schemes A⇆B and A→B→C, and to the general scheme aA+bB+ ...⇆qQ + sS + .... . The results provide a simple quantitative method for selecting favourable catalysts and adsorbents for such adsorptive reactors, and for choosing ideal contact times between the solid and fluid phases when mass transfer limitations are of importance. The analysis is also applied to systems involving solvent-based extraction for reaction enhancement. In this case, the effective reaction Damkohler numbers are shown to involve absorption parameters based on Henry's law (gas-liquid systems) or partition parameters (liquid-liquid systems).
S Fan, SP Gretton-Watson, JHG Steinke, E Alpay (2003)Polymerisation of methyl methacrylate in a pilot-scale tubular reactor: Modelling and experimental studies, In: Chemical Engineering Science58(12)pp. 2479-2490
A pilot-scale tubular reactor fitted with in-line static mixers is experimentally and theoretically evaluated for the polymerisation of methyl methacrylate (MMA). A non-isothermal and non-adiabatic axially dispersed plug-flow model is used to describe the flow characteristics of the reactor. The model is applied to the polymerisation of a concentrated MMA solution (up to 72% (v/v)). Key model parameters were attained through independent bench and pilot-scale experiments. Measured monomer conversions and polymer molecular weight were accurately predicted by model simulation. The presence of static mixers is shown to give near-ideal plug-flow operation for the experimental conditions of this study. Furthermore, an approximately four-fold increase in overall heat transfer coefficient is indicated due to the radial mixing incited by the mixers. Studies also demonstrated the importance of inhibitor kinetics on the dynamic and steady-state performance of the reactor. © 2003 Elsevier Science Ltd. All rights reserved.
E Alpay (2001)Some psychological theories in engineering education, In: Chemical Engineering Education35(3)pp. 212-219
I Yongsunthon, E Alpay (2000)Total connectivity models for adsorptive reactor design, In: Chemical Engineering Science55(23)pp. 5643-5656
The synergetic combination of separation, reaction and heat exchange using multiple fixed beds of adsorbent and catalyst is theoretically explored through the optimization of a general configurational superstructure. The superstructure enables all possible connections between the beds (stages) and the feed and product reservoirs, and is thus referred to as a total connectivity model. Two-step cycle operations are considered involving a reactant feed step and adsorbent regeneration step. Gas flow in each step can be in the same overall direction, or in a reverse-flow arrangement. As a case study, the endothermic dehydrogenation of methylcyclohexane to toluene is considered over an admixture of Pt-alumina catalyst and zeolite 5A adsorbent. The method demonstrates an effective means for generating cyclically operated reactor and adsorber networks which substantially improve upon the production efficiency of an equivalent adiabatic steady-flow reactor, whilst adhering to user-specified bulk separation constraints. For example, optimization of a reverse-flow total connectivity model has led to a process which yields 65% conversion of methylcyclohexane (cf. 23% for an equivalent and optimally operated PFR), with 97% recovery of a toluene product which is 64% pure on an inert-free basis (cf. 11% purity for the PFR). These benefits are achieved for energy inputs which do not exceed that of the steady-flow reactor. When compared to sub-set structures in which, for example, gas recycle is not permitted, the calculations indicate that simple series-parallel connectivity of the stages can provide a comparable performance in terms of conversion and separation. Total connectivity simulation thus establishes the maximum system performance, against which simpler configurations can be evaluated.
E Alpay, D Chadwick, LS Kershenbaum Strategies for enhanced conversions and yields in catalysed reversible reactions, In: Conference Proceedings, Hungarian Journal of Industrial Chemistrypp. 1-8
E Alpay, A Hari, M Kambouri, AL Ahearn (2009)Gender issues in the research environment, In: SEFI 37th Annual Conference 2009
Recruiting and retaining females within science, engineering and technology continues to challenge many European Higher Education Institutions. This study looks at female self-perceptions relating to effective research work and career progression. Focus groups are used to examine the attitudes and experiences of females, and a questionnaire used to explore perceptions in four main skills areas: group work; communication; personal awareness; and project planning and management. The study indicates consistent female concerns on issues pertaining to effective female role models, negative work-role stereotypes and the work-life balance of an academic career. For all four skills areas, the average confidence scores of the female participants fell below that of males, but these differences were only statistically significant for perceptions on group work and communication skills, and prior to an intense skills development course. Based on these findings, a student workshop on gender issues has been developed, an outline of which is presented.
J Sheikh, LS Kershenbaum, E Alpay (2001)1-butene dehydrogenation in rapid pressure swing reaction processes, In: Chemical Engineering Science56(4)pp. 1511-1516
A rapid pressure swing reaction (RPSR) process combines the operations of gas separation by rapid-cycle pressure swing adsorption (RPSA) and catalytic reaction. The hybrid reactor has potential applications to equilibrium limited reactions, in which selective adsorption of reaction species can lead to enhancement in conversion and bulk separation of product species. In this work analytical criteria derived for simplified process configurations are used to guide the selection of adsorbents and catalysts which may lead to reaction enhancement for the 1-butene dehydrogenation reaction scheme A⇆ B + C. Two configurations of the RPSR process are described, and theoretically and experimentally evaluated for the dehydrogenation of 1-butene to 1,3 butadiene over an admixture of CrO2-alumina catalyst and a zeolite K-Y adsorbent. Experimental results show significant concentration of 1,3-butadiene relative to unreacted butene in a particular exit stream, and the beneficial effects of adsorptive separation in lowering the rate of catalyst deactivation due to coking. Simulation data predicts that under certain design conditions an improvement in reactant conversion over the equilibrium limit of the fixed-bed operation is observed, with the additional benefit of bulk separation of reaction products. © 2001 Published by Elsevier Science Ltd.
J Sheikh, LS Kershenbaum, E Alpay Butene dehydrogenation in a co- and counter-currently depressurised adsorptive reactor, In: Hungarian Journal of Industrial Chemistrypp. 52-55
Y Ding, E Alpay (2001)High temperature recovery of CO2 from flue gases using hydrotalcite adsorbent, In: Process Safety and Environmental Protection79(1)pp. 45-51
Experimental and theoretical studies on the high temperature recovery of CO2 from flue gases are presented. The work employs a potassium promoted hydrotalcite adsorbent, for which CO2 capacities in excess 0.8 mol kg-1 were measured at temperatures of 481 K and 575 K and in the presence of high concentrations (∼30% (v/v)) of water. Elution profiles from a bench-scale adsorption unit also enabled analysis of adsorption and desorption kinetics. A cyclic and multibed process for the continuous and energy efficient recovery of CO2 is proposed. The process involves an integrated energy recovery step for the generation of steam, which is then used for the recovery of CO2 from the adsorbed phase. A mathematical model for the CO2-hydrotalcite system, based on measured equilibria and kinetic data, is used for the preliminary assessment of the process, e.g. in terms of CO2 product purity and steam consumption. Particular attention is given to CO2 recovery from the stack gas of a typical 10 MW coal-fired power plant. The work has application to existing industrial processes in which recovered CO2 (at elevated temperatures) can be used as a feedstock for further catalytic processing, such as dry methane reforming and carbon gasification. © Institution of Chemical Engineers.
BW Greenland, S Liu, Gabriel Cavalli, Esat Alpay, JHG Steinke (2010)Synthesis of beaded poly(vinyl ether) solid supports with unique solvent compatibility, In: Polymer51(14)pp. 2984-2992 Elsevier
Poly(vinyl ether) gels SLURPS (Superior Liquid Uptake Resin for Polymer-supported synthesis) with low cross-linking levels have been synthesized for the first time in beaded form using a non-aqueous inverse suspension polymerisation approach. The synthetic protocol was optimized with regards to several parameters including reactions conditions, type and concentration of suspension stabilizer and controlled low temperature addition of co-initiator. Particle size measurements confirm the production of beads with average diameters of 700e950 mm. Optimization of the monomer composition of the poly (vinyl ether) gels resulted in a novel beaded polymer support with considerably improved as well as unique swelling characteristics in solvents ranging from hexane to water. The synthetic utility of the new gel was confirmed by carrying out a set of transformations with complete conversion leading to a useful amino and hydroxy terminated solid-phase precursor resin. Reaction progress could be monitored easily by 1 H and 13C gel-phase NMR
ISK Purnomo, E Alpay (2000)Membrane column optimisation for the bulk separation of air, In: Chemical Engineering Science55(18)pp. 3599-3610
Model-based optimisation is demonstrated for the design and analysis of two generalised membrane systems: a single stage permeator in which there is the recycle of both retentate and permeate gases, and a continuous membrane column in which there is the additional recycle of the retentate stream to the feed line. Multitubular shell-and-tube arrangements are considered with the counter-current flow of tube and shell-side gases; attention is given to the separation of air over several commercial polymeric membranes. A finite element technique is used for the solution of the model equations, and optimisation achieved through standard successive reduced quadratic programming methods. In specific, the maximisation of the Rony separation index is considered at various user-specified product oxygen purities. On this basis, a membrane column is shown to out-perform a single-stage permeator. Optimisation of the Rony index also leads to favourable composition profiles in the enricher and stripper sections of the membrane column, in which, for example, reverse permeation is avoided, and the extent of mixing (dilution) of feed minimised. Furthermore, the optimisation strategy is found to be approximately analogous to the maximisation of the equivalent pure oxygen and nitrogen production rates. Optimisation results for the membrane column indicate the benefits of a relatively small degree of retentate reflux, but negligible benefit of any retentate recycle to the feed line. For a given membrane column size and feed processing rate, membranes of low selectivity (but high permeability) are also shown to yield more favourable molar splits of oxygen and nitrogen than membranes of high selectivity, but at the expense of compressor power requirements. Issues of membrane column scale-up and intensification are also addressed by application of scaling ratio theory to the optimal designs. The theory indicates that for a membrane column designed for the maximum molar split of oxygen and nitrogen, a reduction in compressor power, whilst maintaining this split, can only be achieved at the expense of reduced feed throughput. (C) 2000 Elsevier Science Ltd. All rights reserved.
E Alpay, D Chadwick, LS Kershenbaum, PJ Barrie, C Sivadinarayana, LF Gladden (2003)TEOM analysis of the equilibria and kinetics of n-hexane and n-heptane adsorption on FCC catalyst/silicalite, In: Chemical Engineering Science58(13)pp. 2777-2784
A tapered element oscillatory microbalance is used for the measurement of uptake rates of n-hexane and n-heptane on fluid catalytic cracking catalyst and silicalite adsorbent. Investigations are considered over the temperature range of 373 to 513 K, and adsorbate partial pressures up to 0.12 bar. Based on measured adsorption isotherms, and through mechanistic descriptions of the diffusion process, a mathematical model is developed to describe the transient response of the microbalance, and subsequently the kinetics of adsorption and desorption. For example, for the hexane-silicalite system at a temperature of 473 K, the diffusion coefficient at zero-surface coverage is estimated as 2.9×10-11 m2/s, with an activation energy of 17 kJ/mol. This is consistent with published data based on other transient analysis methods. At relatively low temperatures of operation, i.e. less than 450 K, a single resistance model for mass transfer failed to accurately predict the desorption profiles for hexane on silicalite. As a means of quantifying the observed desorption rates, a dual-resistance model is introduced in which two different diffusion rates are assumed to take place above and below a threshold value of adsorbate concentration. Such a model may be used to account for silicalite phase transitions at high adsorbate loading. © 2003 Elsevier Science Ltd. All rights reserved.
YS Cheng, E Alpay, LS Kershenbaum Simulation and optimisation of a rapid pressure swing reactorpp. S45-S52
O Da-Silva, E Alpay (2003)Removal of organic pollutants from wastewater using humic substances, In: Progress in Water Resources8pp. 125-134
The potential of humic substances in removal of pollutants from wastewater effluents was analyzed. The compost was used as source of humic substances and phenol was used as model organic pollutant. The batch kinetics and isotherm studies were conducted to evaluate capacity of compost for phenol. The dissolved humic substances were precipitated out of solution using iron salts, prior to analysis of residual phenol using high pressure liquid chromatography (HPLC). The results show that maximum capacity of compost for phenol was 1.87 mg/g and humic substances exhibited higher affinity for phenol.
E Alpay (2012)General engineering - Student motivations towards flexibility and breadth in the engineering curriculum, In: Proceedings of the 40th SEFI Annual Conference 2012 - Engineering Education 2020: Meet the Future
Across Europe concerns remain of a shortfall of graduates to meet industry needs and maintain competitive advantage ([1]-[2]). The problem is in part due to student attractiveness to the discipline, but also the variability in progression from a degree course to an engineering career due to motivational changes in educational need ([3], [4]). Several UK universities (as in many other European countries) currently provide a General Engineering (GE) entry to students. The advantages of such entry are typically reported as: (i) the provision of a broader foundation in engineering fundamentals (e.g. engineering maths and science) as well as skills-related components (e.g. design, communication and problem analysis); (ii) allowing students a more informed choice in degree specialisation selection, e.g. the option for students to defer specialisation until course tasters are sampled, or greater awareness of personal preferences in engineering work/application are realised; (iii) the preparation of students for a more versatile career, i.e. graduates who are able to apply their training to other engineering contexts. In this paper, the attractiveness of GE to student recruitment is explored through a national (UK) survey on pre-university (16-18 age group) students. Specifically, attention was given to student motivations towards flexibility in engineering specialisation, combined degree options (e.g. engineering and management) and exposure to other non-technical courses such as politics, business studies and languages. The study therefore addresses the following questions: 1. Is GE entry attractive to students who intend to study engineering? 2. Can GE entry help attract students into engineering who are considering studying a non-engineering mathematics/science based degree? How does this compare to a combined degree option? 3. What are the broader educational elements of university education that are particularly attractive to students? The survey was restricted to students who were undertaking qualifications that enabled entry into engineering degree programmes, e.g. A-levels in both mathematics and physics; a response rate of 1538 from this group was achieved. Attention was given to student motivations towards flexibility in discipline specialisation, combined degree options (e.g. engineering and management) and exposure to other non-technical courses such as politics, business studies and languages. Of those respondents who indicated a desire to enrol on an engineering degree (N=775; 50.4%), 30.7% were undecided on their choice of specialisation and 81.6% indicated a favourable response to a GE type programme. Of those respondents who were not considering an engineering career (N=763), 35.7% indicated a favourable response to a GE programme, i.e. given such a programme, 32.7% would "possibly reconsider" applying to engineering, and 3% would "definitely reconsider". Also for this cohort, 32.9% indicated a favourable response to a combined degree, i.e. 29.4% would "possibly consider" applying to such a programme and 3.5% would "definitely consider". As part of broader university education, "important aspects of other engineering disciplines" was ranked highest by students who were considering an engineering degree, followed by education in leadership, teamwork, environmental and sustainability studies and business skills. Students not considering an engineering degree ranked education in leadership as highest, followed by teamwork, self-awareness/personal development, business skills and international studies. The data indicates the potential attractiveness of GE to student recruitment. Student desires for wider engagement in professional skills development are also apparent, specifically in areas of leadership, teamwork, business skills and self-awareness/personal development.
E Alpay, CN Kenney, DM Scott (1994)Adsorbent particle size effects in the separation of air by rapid pressure swing adsorption, In: Chemical Engineering Science49(18)pp. 3059-3075
Experimental and theoretical investigations into air separation by rapid pressure swing adsorption over zeolite 5A are presented. These concentrate on the effect of adsorbent particle size on the separation performance of the unit undergoing simple cycles consisting of pressurisation and depressurisation steps. An optimum particle size for maximum cyclic equilibrium product oxygen purity is shown to exist; this is accurately predicted by model simulation. Calculations indicate that for beds containing very small particles, a poor separation results from ineffective pressure swing, and for beds containing very large particles from intraparticle diffusional limitations. For the zeolite 5A adsorbent used in this work, theoretical calculations indicate that the rate limiting intraparticle diffusion is described by a parallel combination of molecular and Knudsen diffusion within the macropores of the adsorbent particles. Axial dispersion within the bed is also shown to have a significant effect upon the cyclic equilibrium value of the cycle-average product oxygen purity. In addition to measurements at the cyclic equilibrium, temporal profiles of the product oxygen purity during the approach to cyclic equilibrium are shown. Under certain operating conditions, an overshoot of oxygen purity is found to exist. This behaviour can be attributed to ineffective pressure swing within the product end region of the bed, and thus to the poor utilisation of adsorbent in this region. © 1994.
E Vaitsis, D Chadwick, E Alpay (2004)Slug flow hydrodynamics in the presence of catalyst rods, In: Chemical Engineering Research and Design82(5)pp. 653-658
A design for a slug flow reactor, referred to as the confined slug flow (CSF) reactor, is presented and some hydrodynamic issues for this reactor are considered. Particular attention is given to the prediction of gas bubble and liquid slug velocities and lengths. These parameters are found to be described adequately by modified forms of relationships for conventional slug flow operation. In combination with the continuity equations for slug flow, the modified velocity relationships enable the evaluation of liquid film properties (and subsequently mass transfer coefficients), as well as liquid and gas residence times. The studies demonstrate the possibilities of using catalyst inserts within monolith blocks under slug flow operation, and thus improved flexibility in the design of mass-transfer-enhanced, three-phase, structured reactor systems. © 2004 Institution of Chemical Engineers.
J Sheikh, LS Kershenbaum, E Alpay 1-bulene dehydrogenation in rapid pressure swing reaction processespp. 1511-1516
Salinity gradient solar ponds can be used to store heat by trapping solar radiation. The heat can then be employed to drive various industrial applications that require low-grade heat. In this study, a comprehensive finite difference transient model has been developed incorporating many processes that affect the performance of a solar pond to predict the hourly temperature distribution. A novel heat extraction method for salinity gradient solar ponds is then proposed. This method can be operated in batch or continuous modes. A comparison between the performance of two solar ponds of the same size (10,000 m2) in Adana (Turkey) and Ahvaz (Iran) is also presented. The heat extraction method entails brine removal from the Non-Convective Zone (NCZ) as well as the HSZ. The presented model incorporates the heat losses from the bottom and surface of the pond as well as the cooling effect imposed as a consequence of the replacement of extracted brine from each layer, and the supply of freshwater to the surface of the pond to maintain its inventory. The model can be employed to predict the performance of solar ponds of various dimensions for any given location. In the final part of this study, utilisation of solar thermal energy from salinity gradient solar ponds in forward osmosis (FO) is investigated. This study will present two novel processes for the regeneration of dimethyl ether (DME) and ammonium bicarbonate as a draw solutes in FO using thermal energy provided from a solar pond. The average daily volume of desalinated water produced using these processes and a solar pond of 10,000 m2 was determined. It is indicated that, a solar pond of such moderate size can drive a forward osmosis plant to provide a total of 5,210 m3 of potable water in the first two years of operation in the location considered in this study (Chabahar) if DME is used as the draw solute. The proposed process can provide freshwater at varying rates throughout the year and benefits from a very low electricity consumption rate of 0.46 kWh per cubic metre of desalinated water presenting a viable option for solar desalination. In case of ammonium bicarbonate, the product water contains small quantities of ammonia ions making it unsuitable for drinking purposes. Given that there are vast uninhabited coastal areas in many countries, particularly in the MENA region where there are high solar radiation rates, this method can contribute towards addressing the growing water scarcity.
As the regulatory limitations of hard-chrome plating surge, the successful application of thermal- sprayed wear/corrosion resistant coatings on complex geometries becomes critical. Thermal spraying is a line-of-sight method and thus, spraying a complex geometry results to changes in the spray angle, the spray distance and the effective gun traverse speed. Although there has been some research on the effects of these kinematic parameters on the coatings, previous work tends to examine the kinematic parameters in isolation, disregarding of any interplay between them. Yet, the effective particle velocity at impingement is dictated both by spray angle and spray distance while the particle temperature is mainly dictated by spray distance. In addition, the heat and mass transfer to the underlying coating are controlled by the gun traverse speed. These facts suggest that significant synergistic effects are expected when the spray kinematic parameters vary simultaneously, as when a complex geometry is sprayed. This work aims at evaluating the systemic effect of the spray kinematic parameters on WC-Co coatings sprayed by HVOF. Various coating properties are comprehensively examined and discussed, exploring the microstructures, phase composition, mechanical qualities and tribological performance. Significant interplay between the spray kinematic parameters is demonstrated in a number of coating properties, yielding non-linear behaviours. The notable beneficial role of small spray angle inclinations at long spray distances, in regards to deposition rate, microstructure, microhardness and wear resistance is demonstrated. Mechanisms of the particle rebounding, superficial oxidation of the coating, metallic tungsten crystallization, tribofilm formation and wear damage progression are proposed, with respect to the spray kinematic parameters. Finally, an attempt to generalize the insights from this work to any given sprayable geometry takes place in a prototype software tool in Matlab.