Professor Esat Alpay

The use of 3D printers in higher education is becoming increasingly popular, with initiatives being reported in areas such as prototype development, design exploration and component/process visualisation. Diverse and cross-discipline applications in areas such as bio- and medical engineering, food processing and chemical product engineering are also rapidly emerging. The integration of 3D printers into engineering curricula is leading to an interest in pedagogy, and specifically innovative approaches to enhance teaching quality. The chapter provides an evaluation of such 3D printer use with discussion on future potential applications. The methodological approach has involved a literature review of current 3D printer uses in school and higher education contexts, an evaluation of the training requirements to enable wide accessibility of 3D printing, and stakeholder surveys and interviews.

The process operations and management (POM) module offered by the University of Surrey’s Chemical and Process Engineering Department, in which students take charge of pilot-scale industrial equipment, is thought to create a learning environment which challenges undergraduates to develop their transferable skills. This study aimed to assess how effective the POM module is at improving student perceptions of their transferable skills by using questionnaires. The students reported high learning in the areas assessed, and an increased appreciation for transferable skills. The results indicate that the interest in UK Chemical Engineering departments for using pilot plants as a tool for effective teaching is justified, although care must be taken to make the most of the opportunities they provide when designing the modules that use them.

Despite increasing attention and calls for transdisciplinary (TD) working in engineering, a lack of clarity surrounding what constitutes a TD research approach persists. This paper aims to reduce ambiguity by characterising TD and identifying when the TD approach should or should not be used. Specifically, the research answers the question: when might it be beneficial to take a TD rather than a single, multi or interdisciplinary research approach? Survey responses from twenty-eight authors (50%) who presented papers at the 28 th ISTE International Conference on Transdisciplinary Engineering (TE2021) were qualitatively analysed. Findings show a TD approach to research is beneficial for complex problem-solving. New understanding reveals that TD could be used to evidence scientific and social impact, and that context determines the appropriateness of TD adoption. However, even where TD adoption is deemed appropriate, institutional barriers to adoption may exist. In other words, the work environment (culture) in which we do our research, may determine if any meaningful benefits from TD are, or are not realised. Lessons from engineering education are used to discuss how to institutionalise TD, future transdisciplinary engineers and researchers might be taught and socialised in the competencies needed for transdisciplinary research.

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.

The use of VR in engineering education provides a means for contextualising learning through authentic and engaging scenarios, e.g. the touring and operation of a chemical plant. This paper presents the design of an immersive VR simulation of an existing pilot plant in the School and its evaluation through a randomised non-inferiority trial to test student learning compared to a more traditional learning medium. Specifically, the study evaluates information retention (i.e. memory and understanding) when using the VR simulation and compares this to information retention when presented as a multimedia instructional video. Student self-efficacy in plant operation and design (e.g. equipment function and operation), as well as engagement in the learning activity, are also evaluated. The results indicate that both the VR and multimedia-based activities lead to comparable data retention and student self-efficacy. Moreover, students enjoyed the VR experience and welcomed the addition of the resource to their educational materials.

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.

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.

ABSTRACT Tensions between the research and teaching roles in university are well recognised. Past teacher training practices have only partially considered such issues and indeed the motivations, bias and priorities of the teaching researcher. This paper provides an overview of teacher training (content and process) that is suited for the research-focused environment. Particular attention is given to a training approach that has been recently adopted at Imperial College London. The approach involves practice-based and experiential learning, support and input from a broad community (e.g. peers, senior peers and education experts), clear discipline contextualisation and ownership, and emphasis on the potential parallels between teaching and research and the value of teaching to research. Furthermore, teaching practices that capitalise on researcher and institutional strengths are encouraged, and exemplified through the notion of research-supporting teaching. RESUMEN Respaldo al investigador que es también docente Las tensiones entre los roles investigadores y docentes en la universidad son de sobras conocidas. Hasta la fecha, la formación del profesorado sólo ha tenido en cuenta de forma parcial esta problemática, así como las motivaciones, predisposición y prioridades del investigador que es a la vez profesor. Este artículo ofrece una descripción general de la formación del profesorado (en cuanto a contenido y a proceso) adecuada a un entorno enfocado a la investigación. Concretamente se da información sobre el planteamiento de la formación adoptado recientemente por la universidad Imperial College London. Este enfoque incluye aprendizaje experiencial basado en la práctica, apoyo e input de una amplia comunidad (por ejemplo pares, pares sénior y expertos en educación), clara contextualización respecto a la disciplina y propiedad/interiorización, y énfasis en los potenciales paralelismos entre docencia e investigación así como el valor de la docencia para la investigación. Además, se promueven aquellas prácticas docentes que aprovechan el rol investigador y el potencial institucional, y se ejemplifican mediante la noción de docencia que respalda la investigación.

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 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.

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.

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.

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.

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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).

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.

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.

Background: The concept of pedagogic frailty has been proposed as a unifying concept that may help to integrate institutional efforts to enhance teaching improvement within universities by helping to maintain a simultaneous focus on four key areas that are thought to impede development. Purpose: The variation in internal structure of the four dimensions of pedagogic frailty and the links that have been proposed to connect them are explored here through the analysis of interviews with academics working in a variety of disciplinary areas. Methods: The application of concept map-mediated interviews allows us to view the variable connections within and between these dimensions and the personal ways they are conceptualised by academics working across the heterogeneous university context. Results: The data show that academics conceptualise the discourse of teaching in various ways that have implications for the links that may be developed to integrate the elements within the model. Conclusions: Whilst the form and content of the maps representing dimensions of the pedagogic frailty model exhibit considerable variation, it is suggested that factors such as academic resilience and the explicit use of integrative concepts within disciplines may help to overcome some of the vulnerabilities that accompany pedagogic frailty. The data also raises questions about the links between factors that tend to be under individual control and those that tend towards institutional control.

Several European universities provide entry to general engineering studies prior to degree specialisation. The potential advantages of such entry include the provision of a broader foundation in engineering fundamentals, the option for students to defer specialisation until a greater awareness of the different engineering disciplines and the preparation of students for a more versatile career. In this paper, the attractiveness of general engineering (specifically in the first year of study) is explored through a national (UK) survey on pre-university students. Attention is given to gauging student enthusiasm for flexibility in engineering specialisation, combined degree options and exposure to other non-technical courses. The findings indicate that a general engineering programme is highly attractive to students who are currently considering an engineering degree. The programme is also attractive to some students who had previously not considered engineering. For both sets of students, the desire for education on broader topics is indicated, specifically in areas of leadership, teamwork and business skills, and more generally self-awareness and personal development.

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.

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.

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.

This article presents and analyzes existing taxonomies of virtual and augmented reality and demonstrates knowledge gaps and mixed terminology, which may cause confusion among educators, researchers, and developers. Several such occasions of confusion are presented. A methodology is then presented to construct a taxonomy of virtual reality and augmented reality applications based on a combination of: a faceted analysis approach for the overall design of the taxonomy; an existing taxonomy of educational objectives to derive the educational purpose; an information systems analysis to establish important facets of the taxonomy; and two systematic mapping studies to identify categories within each facet. Using this methodology, a new taxonomy is proposed and the implications of its facets (and combinations of facets) are demonstrated. The taxonomy focuses on technology used to provide the virtual or augmented reality as well as the content presented to the user, including the type of gamification and how it is operated. It also accommodates a large number of devices and approaches developed throughout the years and for multiple industries, and provides a way to categorize them in order to clarify communication between researchers, developers, and educators. Use of the taxonomy is then demonstrated in two case studies-a virtual reality chemical plant for use in chemical engineering education and an augmented reality dog for veterinary education.

Cross-departmental schemes to broaden the inter-professional and skills-focused development of engineering students, and to emphasise engineering in its context of societal priorities, are presented. The central coordination of the schemes has streamlined implementation of the developments and promoted a culture of shared responsibility for engineering education. A description of the coordination effort, and subsequent mechanisms for promoting strategic educational development, is given. This will be of value to institutions that are attempting to organise educational initiatives across multiple engineering departments. Examples are given to demonstrate the range of learning outcomes that can be achieved through such cross-departmental approaches. Evaluation data are also presented on the value and impact of these approaches. Specific schemes that are described include: the Engineering Impact series of lectures; flexible timetabling for shared option-courses across departments; a common framework for engineering ethics engagement; the establishment of a new academic role for the support of student-led projects.

Recent years have seen an increasing emphasis placed upon the development of transferable skills within PhD degree programmes. This paper reports on steps taken to evaluate a programme of transferable skills development at a research intensive university in the UK, focussing on the views of late stage PhD students in the science, engineering and medical disciplines. It shows that most students report a positive impact from having taken part in transferable skills initiatives and that they have a positive attitude towards them. Participants report an enduring positive impact on their behaviour and consider that the training meets their perceived needs as they progress as researchers. However, amongst the population as a whole, there were differences in views. For example, it was found that females, overseas students and those mainly motivated to do the PhD by career-related reasons attach the greatest importance to such opportunities to develop transferable skills.

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.

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.

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).

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.

Many teachers in higher education will have experiences of the debilitating effects of stress on student motivation, performance and well-being. Dave Putwain (‘Examination stress and test anxiety’, December 2008) discusses some of the key reasons leading to examination stress in GCSE students, and these are of course also valid to other student groups. However, as someone who has been running stress management workshops for both undergraduate and postgraduate students, I believe further elaboration and extension is needed in explaining some of the causes of exam stress at the university level.

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.)

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.

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.

Both virtual reality (VR) and augmented reality (AR) have undergone considerable development in recent years. Even though it seems that we are still in a primitive technological stage, it is already recognised that VR/AR can provide exciting opportunities to support teaching and learning [1]. There have been numerous attempts to use this technology in education contexts [2], in most cases showing success [3]. Example include military training applications [4], engineering applications through VR laboratories [5], and history [6] and astronomy [7] education. The possibilities to use VR/AR transcend to other contexts, such as interactive performances, theatre, galleries, discovery centres and so on [8]. The advantage of VR as an experimental and educational tool is the ability to place the participant inside any scene with high degree of immersion [9]. However, there are also examples where educational application has only been partially successful, such as the use of 3D anatomy models in medical education [10] or skill transfer in VR based microsurgery training [11]. Greater understanding is needed as to the features of such applications that are especially conducive to student learning. More fundamentally though, clarity is needed on the classification of the tools to accurately describe e.g. function and design.

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).

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.

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.

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.