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 (
Yongsunthon I, Alpay E A temperature-cycled adsorptive reactor for the enhancement of catalytic reaction, pp. 1173-1176
Purnomo ISK, Alpay E (2000) Membrane column optimisation for the bulk separation of air, Chemical Engineering Science 55 (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.
Sheikh J, Kershenbaum LS, Alpay E Butene dehydrogenation in a co- and counter-currently depressurised adsorptive reactor, Hungarian Journal of Industrial Chemistry pp. 52-55
Alpay E, Chadwick D, Kershenbaum LS, Barrie PJ, Sivadinarayana C, Gladden LF (2003) TEOM analysis of the equilibria and kinetics of n-hexane and n-heptane adsorption on FCC catalyst/silicalite, Chemical Engineering Science 58 (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.
Koumpouras GC, Alpay E, Stepanek F (2007) Mathematical modelling of low-temperature hydrogen production with in situ CO2 capture, Chemical Engineering Science 62 (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.
Sheikh J, Casasempere-Miralles I, Kershenbaum LS, Alpay E Experimental investigations of butadiene hydrogenation in a rapid pressure swing reactor, Proceedings of the 1997 Jubilee Research Event pp. 1033-1036
Al-aibi S, Mahood HB, Mahood HB, Sharif AO, Sharif AO, Alpay E, Simcoe-Read H (2015) Evaluation of draw solution effectiveness in a forward osmosis process, Desalination and Water Treatment
© 2015 Balaban Desalination Publications. All rights reserved. This work investigates the effectiveness of sodium chloride and sucrose binary draw solutions in a forward osmosis pilot plant unit with either deionised or salt water feeds. Specifically, the effects of draw solution concentration on water flux through the membrane, the overall water recovery and the specific energy consumption of the unit are considered. For both feed types, sodium chloride draw solution exhibited a relatively high effectiveness in terms of all the measured performance indicators. Further, improvements in flux and recovery were also achievable with an increase in the sodium chloride (draw solution) concentration. In contrast, a sucrose-based draw solution led to a severe deterioration of the membrane performance that could not be effectively overcome by an increase in the draw solution concentration. This observation was attributed to the relatively large increase in the viscosity of the draw solution with increase in sucrose concentration. Interestingly, in the case of a salt water feed, an increase in the sucrose draw solution concentration led to a relatively small increase in flux and recovery, suggesting some complex but favourable interaction between the salt and sucrose due to the reverse diffusion of the salt into the draw solution.
ALPAY E, KERSHENBAUM LS, KIRKBY NF (1995) PRESSURE CORRECTION IN THE INTERPRETATION OF MICROREACTOR DATA, CHEMICAL ENGINEERING SCIENCE 50 (6) pp. 1063-1067 PERGAMON-ELSEVIER SCIENCE LTD
Gretton-Watson SP, Alpay E, Steinke JHG, Higgins JS (2005) Hyperbranched polymers. Synthesis, modeling, experimental validation, and rheology of hyperbranched poly(methyl methacrylate) derived from a multifunctional monomer (MFM) route, Industrial and Engineering Chemistry Research 44 (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.
Fan S, Gretton-Watson SP, Steinke JHG, Alpay E (2003) Polymerisation of methyl methacrylate in a pilot-scale tubular reactor: Modelling and experimental studies, Chemical Engineering Science 58 (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.
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.
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).
Alpay E, Ahearn AL, OyeLeye FO, Bull AMJ The impact of extra-curricular activities on the development and motivation of engineering students, Proceedings of the 37th IGIP Symposium
Alpay E (2013) Peer-feedback and the paradox of knowing, Psychologist 26 (9)
Alpay E, Haq N, Kershenbaum LS, Kirkby NF (1996) Adsorption parameters for strongly adsorbed hydrocarbon vapours on some commercial adsorbents, GAS SEPARATION & PURIFICATION 10 (1) pp. 25-33 BUTTERWORTH-HEINEMANN LTD
Alpay E, Gulati S (2010) Student-led podcasting for engineering education, European Journal of Engineering Education 35 (4) pp. 415-427
The use of podcasts is challenging traditional communication methods in higher education, with the potential for creating engaging and flexible resources for learning and development. Likewise, podcasts are helping to facilitate a stronger student identity and community within learning environments, replacing traditional student newsletter and website approaches. In this work, an innovative podcasting approach is presented in which there is a strong student-centred and student-led premise to foster and advance engineering education-related uses. Podcasts are intended to cover a range of relevant engineering topics, such as sharing student views on global, institutional and scientific developments and disseminating information on unique educational opportunities. Details on the design, set-up and implementation of the initiative are presented (e.g. resource requirements, management and organisation structures, maintenance of balanced educational outcomes). An evaluation of the experiences of the team members is also presented, showing favourable outcomes in skills development, community identity and broader educational awareness. © 2010 SEFI.
Alpay E (2011) Student-inspired activities for the teaching and learning of engineering ethics., Sci Eng Ethics 19 (4) pp. 1455-1468
Ethics teaching in engineering can be problematic because of student perceptions of its subjective, ambiguous and philosophical content. The use of discipline-specific case studies has helped to address such perceptions, as has practical decision making and problem solving approaches based on some ethical frameworks. However, a need exists for a wider range of creative methods in ethics education to help complement the variety of activities and learning experiences within the engineering curriculum. In this work, a novel approach is presented in which first-year undergraduate students are responsible for proposing ethics education activities of relevance to their peers and discipline area. The students are prepared for the task through a short introduction on engineering ethics, whereby generic frameworks for moral and professional conduct are discussed, and discipline and student-relevance contexts provided. The approach has been used in four departments of engineering at Imperial College London, and has led to the generation of many creative ideas for wider student engagement in ethics awareness, reflection and understanding. The paper presents information on the premise of the introductory sessions for supporting the design task, and an evaluation of the student experience of the course and task work. Examples of proposals are given to demonstrate the value of such an approach to teachers, and ultimately to the learning experiences of the students themselves.
Kolade MA, Kogelbauer A, Alpay E (2009) Adsorptive reactor technology for VOC abatement, Chemical Engineering Science 64 (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.
Masouros SD, Alpay E, Alpay E (2010) Mathematics and online learning experiences: A gateway site for engineering students, European Journal of Engineering Education 35 (1) pp. 59-78
This paper focuses on the preliminary design of a multifaceted computer-based mathematics resource for undergraduate and pre-entry engineering students. Online maths resources, while attractive in their flex- ibility of delivery, have seen variable interest from students and teachers alike. Through student surveys and wide consultations, guidelines have been developed for effectively collating and integrating learning, support, application and diagnostic tools to produce an Engineer's Mathematics Gateway. Specific rec- ommendations include: the development of a shared database of engineering discipline-specific problems and examples; the identification of, and resource development for, troublesome mathematics topics which encompass ideas of threshold concepts and mastery components; the use of motivational and promotional material to raise student interest in learning mathematics in an engineering context; the use of general and lecture-specific concept maps and matrices to identify the needs and relevance of mathematics to engineering topics; and further exploration of the facilitation of peer-based learning through online resources. © 2010 SEFI.
Alpay E, Cutler PS, Eisenbach S, Field AJ (2009) Changing the marks based culture of learning through peer assisted tutorials, ASEE Annual Conference and Exposition, Conference Proceedings
We describe and evaluate an approach to student learning that aims to instil a culture of formative assessment based on peer-assisted self learning, instead of a marks-based culture in which learning effort is rewarded with marks that contribute to the student's degree. The idea is for suitably qualified third- and fourth-year undergraduates to assist in the running of weekly first-year tutorials. They mark submitted work, provide written and verbal feedback on the students' performance and lead problem solving discussions during tutorials. However, contrary to normal practice, the marks they award do not contribute to the students' year total; all tutorial work becomes essentially voluntary. We report results from a pilot implementation of the scheme over a 12-month period in an engineering department at a leading academic institution. The set-up of the scheme was such that a comparative and triangulated assessment was possible amongst the students and tutor team. There was no discernible degradation in student attendance, submission rates and performance in either the weekly exercises or end of year examinations. Further analysis demonstrates that this type of peer-assisted learning improves some key aspects of student learning, and provides important benefits to the senior peers in terms of their own personal development. We conclude that the scheme provides an excellent alternative to traditional learning methods whilst substantially reducing the investment in academic staff time. © American Society for Engineering Education, 2009.
Sheikh J, Kershenbaum LS, Alpay E (2001) 1-butene dehydrogenation in rapid pressure swing reaction processes, Chemical Engineering Science 56 (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 AÆ 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.
Chatsiriwech D, Alpay E, Kershenbaum LS, Kirkby NF The enhancement of catalytic reaction by pressure swing adsorption, Proceedings of the 1994 IChemE Research Event pp. 655-657
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.
Alpay E (2001) Some psychological theories in engineering education, Chemical Engineering Education 35 (3) pp. 212-219
Greenland BW, Greenland BW, Liu S, Cavalli G, Cavalli G, Alpay E, Steinke JHG (2010) Synthesis of beaded poly(vinyl ether) solid supports with unique solvent compatibility, Polymer 51 (14) pp. 2984-2992
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 700-950 ¼m. 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 1H and 13C gel-phase NMR. © 2010 Elsevier Ltd.
Yongsunthon I, Alpay E (2000) Total connectivity models for adsorptive reactor design, Chemical Engineering Science 55 (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.
Alpay E, Ahearn AL, Bull AMJ Cross-Departmental Initiatives for a Global Dimension in Engineering Education,
Alpay E, Hari A, Kambouri M, Ahearn AL (2009) Gender issues in the research environment, 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.
Sheikh J, Kershenbaum LS, Alpay E (1998) Analytical basis for separation enhanced reaction in continuous flow processes, Chemical Engineering Science 53 (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 AÆB and ABC, and to the general scheme aA+bB+ ...ÆqQ + 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).
Koumpouras G, Alpay E (2005) A structured reactor approach to sorption-enhanced hydrogen production, 7th World Congress of Chemical Engineering, GLASGOW2005, incorporating the 5th European Congress of Chemical Engineering
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).
Alpay E, Kenney CN, Scott DM (1993) Simulation of rapid pressure swing adsorption and reaction processes, Chemical Engineering Science 48 (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.
Alpay E, Amesbury H, Burke CP Natural Engineering ? Developing an interdisciplinary course on nature and biology-inspired engineering design,
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
H and 13C gel-phase NMR
Alpay E, Cutler PS, Eisenbach S, Field AJ (2010) Changing the marks-based culture of learning through peer-assisted tutorials, European Journal of Engineering Education 35 (1) pp. 17-32
We describe and evaluate an approach to student learning that aims to instil a culture of formative assessment based on peer-assisted learning. The idea is for suitably qualified undergraduates to assist in the running of weekly first-year tutorials. They mark submitted work, provide written and verbal feedback and lead problem-solving discussions during tutorials. However, contrary to normal practice, the marks they award do not contribute to the students'end-of-year total; all tutorialwork becomes essentially voluntary.We report results from a pilot implementation of the scheme over a 12 month period in an engineering department at a leading academic institution. The scheme was such that a comparative and triangulated assessment was possible among the students and tutor team. Results show no discernible degradation in student attendance, submission rates and performance in either the weekly exercises or end-of-year examinations. Important benefits to the peer tutors are also found. © 2010 SEFI.
Alpay E (2011) Wish i wasn't here?, Psychologist 24 (9) pp. 626-627
Alpay E The student design of resources for ethics education,
Alpay E, Ahearn AL, Graham RH, Bull AMJ (2008) Student enthusiasm for engineering: Charting changes in student aspirations and motivation, European Journal of Engineering Education 33 (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.
Alpay E, Verschoor R (2014) The teaching researcher: Faculty attitudes towards the teaching and research roles, European Journal of Engineering Education 39 (4) pp. 365-376
Results from a survey on faculty attitudes towards the teaching and research roles are presented. Attention is given to: (i) the perceived value of teaching (and teaching achievements) relative to research, (ii) approaches for research and teaching integration, (iii) the satisfaction gained from typical work tasks, and (iv) the importance of various work-life factors. Factors such as academic freedom, an intellectual work environment, flexible work hours, inspirational colleagues, and work diversity are found to be highly valued. Support from peers and colleagues is also seen as a key in learning to manage the different academic roles. A relatively low value is attributed to teaching achievements. Likewise, there is often little utilisation of teaching opportunities to support research work (other than senior-year research projects). Female faculty were found to give marginally a higher importance to teaching recognition and collaborative teaching opportunities. Based on the findings, general recommendations for supporting the teaching researcher are presented. © 2014 SEFI.
Alpay E, Jones ME (2012) Engineering education in research-intensive universities, European Journal of Engineering Education 37 (6) pp. 609-626
The strengths and weaknesses of engineering education in research-intensive institutions are reported and key areas for developmental focus identified. The work is based on a questionnaire and session summaries used during a two-day international conference held at Imperial College London. The findings highlight several common concerns, such as the need to improve faculty motivation towards teaching, broaden the workplace skills of students, widen employer engagement in teaching and raise the relevance and value of scholarly activity in the discipline of engineering education. Examples of good practice used to address such issues are reported. © 2012 Copyright Taylor and Francis Group, LLC.
Alpay E, Jones ME Strengths and weaknesses of teaching in research intensive universities,
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.
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.
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 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
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.