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The present study provides a viable route to solar syngas production and conversion to fine chemicals using renewable energy sources and rendering CO2 a valuable reactant instead of a waste. It uses existing facilities and on-going breakthrough technological advancements from CO2 transportation to H2O/CO2 solar co-splitting for syngas formation to further conversion to either methanol or Fischer-Tropsch (FT) products. A full scale simulation of the overall chemical process is established, considering its subsections with respect to all relevant cost elements and operating expenses using appropriate cost correlations. Eight spanning routes of the CO2 superstructure are assessed for a real case of transporting compressed pure or mixtures of CO2 with a 130 kg/s capacity over a distance of 120 km from a power plant in Ptolemaida, Greece, operating with either natural gas or coal, and combining with water from an existing wastewater treatment facility in Thessaloniki, Greece. It is estimated that the choice of producing methanol requires an investment of ˜€7B and ˜€430 M/y to operate, while for FT-related plants it would cost >€3B to build and ˜€190 M/y to operate. Applying a standard feed-in tariff (FIT) value in terms of subsidization of the energy consumed by renewable sources boosts the expenditure resulting for the best case to a yearly net profit of ˜€500 M or ˜€100 M, for methanol or FT products, respectively. Other scenarios are also considered, including the best spanning route for the minimum FIT revenues by the break-even method, or the required carbon price without any subsidization of the proposed schemes.

A tutorial on the use of Side-Stream Reactor (SSR) technology is presented for screening different combustion engine particulate reduction technologies using small-scale filter segments in a well-controlled environment under realistic engine exhaust conditions. The testing examples include the evaluation of particulate filter flow resistance, soot loading, and soot oxidation (regeneration) performance.

This work is a first simplified approach on the exploitation of “direct” solar heat during on-sun operation, and stored solar-heat through thermochemical energy storage involving redox pair cycles during off-sun operation, for the production of solar hydrogen using concentrated solar energy. The coupling of the processes in a compact solar reforming–thermochemical heat storage system is conducted in terms of a lumped dynamic model; for the determination of the syngas composition in the reforming unit, thermodynamic equilibrium is assumed, while the required heat to facilitate the endothermic reforming reactions is provided by either solar heat (on-sun operation), or a combination of stored energy and an optimal linear profile of external heat provision (off-sun operation). The optimal heat management policy for the reduction or the oxidation step (during the solar heat storage and release process) ensures a steady H2 molar fraction for most of the operating time. It is revealed that the coupled scheme suggested is an in-principle viable option for sustainable H2 production, since reforming needs are entirely complemented by solar heat also supplying the required energy input for the storage unit, which in turn may provide almost 25% of the overall reforming energy needs under off-sun operation.

SSCI-VIDE+ING+FRM:NOG:YSC; International audience; In this study, a robust and efficient decentralized fuel processor based on the direct autothermal reforming (ATR) of biogas with a nominal production rate of 50 Nm3/h of hydrogen and a plant efficiency of about 65% was developed and tested. The ATR unit is composed of a structured catalyst support for the biogas reforming close coupled to a catalytic wall-flow filter to retain eventual soot particles.The performance of the conventional random foam and homogeneous lattice supports structures for the production of hydrogen from the ATR reaction was investigated. 15–0.05 wt%-Ni-Rh/MgAl2O4-SiSiC structured catalyst and LiFeO2-SiC monolith were selected for the conversion of biogas to hydrogen and for the syngas post-treatment process, respectively. For all the experiments, a model synthetic biogas was used and the catalytic activities were evaluated in three different experimental facilities: lab bench, pilot test rig and demonstration plant. High methane conversions (>95%) and hydrogen yields (>1.8) reached in the lab bench were also achieved in the pilot and demonstration plant operating at different GHSV.Results of duration test using a foam coupled to the filter has demonstrated that the pre-commercial processor is reliable while offering a satisfactory reproducibility and negligible pressure drop. A thermodynamic equilibrium and a cold gas efficiency of 90% were reached for an inlet temperature of 500 °C, O/C: 1.1 and S/C: 2.0, as predicted with the Aspen simulation.

The present work aims to establish a methodology for the optimization of CO2 transportation networks by developing transportation levelized-cost functions for the mixture CO2:N2 (96:4%) within the ranges {25–2000 kg/s} and {50–2000 km}, locating the optimal solar cities (locations-sinks) to receive CO2 for further transformation into fine chemicals, and mapping the optimal routes which present the minimum transportation and utilization cost. Potential economies of scale of merging same-route sinks into a joint pipeline are scrutinized by selecting 17 CO2 sources from thermal power and combustion stations in the central EU region aggregating almost 3000 kg/s of CO2; these amounts are optimally allocated to 16 available sinks, which combine maximum solar capacity with the least distance to major ports. This study makes use of transport cost correlations, while the solar potential of the most promising solar cities is calculated in detail based on solar intensity databases and solar power plants cost assessment. Mixed-integer nonlinear programming (MINLP) techniques are incorporated in the optimization procedure under sinks capacity constraints. A major conclusion of this work is that for the mass flowrates considered and the sources locations chosen in the current study it is economically beneficial to transfer CO2 directly to the final sinks from the original sources rather than via intermediate sources. The MINLP formulation derives values of solar utilization cost of over €7B and transportation cost of over €2B per year covering transportation pipelines distances of 34,000 km: precise economic estimates of the proposed methodology regarding CO2 transportation and utilization might have significant implications on energy and environmental policy issues on European or global scale.

The “holy grail” of solar chemistry and solar engineering, is the technical storage of solar energy into a more easily transformable and transportable form, namely an energy carrier such as H2. The two-step redox-based solar thermochemical H2O splitting cycle is considered to be among the most promising approaches for the production of H2 from entirely renewable sources (solar energy and water). In this redox cycle an active material is initially reduced thermally under inert atmosphere and at the next step it is oxidized from H2O producing H2. The materials that have been in the core of solar chemistry research are metal oxides such as ferrites, cerium oxides, perovskites, etc. The reactor types that are being investigated for the redox thermochemical splitting of H2O are either powder-particle reactors or structured reactors. In the current work Ni-ferrite and Ce-oxide structured into different monolithic bodies (honeycombs, foams) were evaluated w.r.t. their redox activity. Based on this investigation, the most promising structure was further scaled-up for the construction of the full-scale reactors of the HYDROSOL-PLANT solar plant installation.The “holy grail” of solar chemistry and solar engineering, is the technical storage of solar energy into a more easily transformable and transportable form, namely an energy carrier such as H2. The two-step redox-based solar thermochemical H2O splitting cycle is considered to be among the most promising approaches for the production of H2 from entirely renewable sources (solar energy and water). In this redox cycle an active material is initially reduced thermally under inert atmosphere and at the next step it is oxidized from H2O producing H2. The materials that have been in the core of solar chemistry research are metal oxides such as ferrites, cerium oxides, perovskites, etc. The reactor types that are being investigated for the redox thermochemical splitting of H2O are either powder-particle reactors or structured reactors. In the current work Ni-ferrite and Ce-oxide structured into different monolithic bodies (honeycombs, foams) were evaluated w.r.t. their redox activity. Based on this investigation,...

The EU emission standards for new rail diesel engines are becoming more stringent: stage IV emission targets have just come into effect, while stage V is in under considerations. Both exhaust gas recirculation (EGR) and selective catalytic reduction (SCR) technologies can be used to reduce nitric oxide (NOx) emissions, while the PM emission control requires a diesel particulate filter (DPF). The use of SCR requires on-board storage of urea, while the use of DPF needs to take into account its impact on engine efficiency performance. Both of these technologies require specific studies when applied to the rail engines; in particular, it becomes necessary to evaluate the engine performance trade-offs in order to evaluate how these technologies can be utilized efficiently in rail applications in order to meet current and future emission standards. The present study assesses the application of these technologies in diesel railcars on a quantitative basis using one- and three-dimensional numerical simulation tools. In particular, the study considers a 560-kW railcar engine with the use of different technology combinations for NOx reduction: SCR or EGR + DPF, and EGR + DPF + SCR. The NOx and PM emission performances are evaluated over the C1 homologation cycle and, in the case of the DPF, over an approximated railcar driving cycle as well. Several BSNOx targets were considered: 2 g/kWh, 1 g/kWh, and 0.4 g/kWh. Simulation results indicate that EGR + DPF + SCR-based solution is necessary to achieve stage IV emission limits for the 560-kW engine. On the other hand, SCR-based solutions have the potential to go beyond the stage IV NOx limit through scaling up the size of the SCR device and the on-board urea storage.

The present work provides an overview of activities performed in the framework of the EU-funded collaborative project RESTRUCTURE, the main goal of which was to develop and validate a compact structured reactor/heat exchanger for thermochemical storage driven by 2-step high temperature redox metal oxide cycles. The starting point of development path included redox materials qualification via both theoretical and lab-scale experimental studies. Most favorable compositions were cobalt oxide/alumina composites. Preparation of small-scale structured bodies included various approaches, ranging from perforated pellets to more sophisticated honeycomb geometries, fabricated by extrusion and coating. Proof-of-concept of the proposed novel reactor/heat exchanger was successfully validated in small-scale structures and the next step included scaling up of redox honeycombs production. Significant challenges were identified for the case of extruded full-size bodies and the final qualified approach related to preparation of cordierite substrates coated with cobalt oxide. The successful experimental evaluation of the pilot reactor/heat exchanger system constructed motivated the preliminary techno-economic evaluation of the proposed novel thermochemical energy storage concept. Taking into account experimental results, available technologies and standard design aspects a model for a 70.5 MWe CSP plant was defined. Estimated LCOE costs were calculated to be in the range of reference values for Combined Cycle Power Plants operated by natural gas. One of main cost contributors was the storage system itself, partially due to relatively high cost of cobalt oxide. This highlighted the need to identify less costly and equally efficient to cobalt oxide redox materials.

The field of nanomedicine is steadily growing and several nanomedicines are currently approved for clinical use with even more in the pipeline. Yet, while the use of nanotechnology to improve targeted drug delivery to the lungs has received some attention, the use of nanoparticles for inhalation drug delivery has not yet resulted in successful translation to market as compared to intravenous drug delivery. The reasons behind the lack of inhaled nanomedicines approved for clinical use or under preclinical development are unclear, but challenges related to safety are likely to contribute. Although inhalation toxicology studies often begin using animal models, there has been an increase in the development and use of in vitro air-liquid interface (ALI) exposure systems for toxicity testing of engineered nanoparticle aerosols, which will be useful for rapid testing of candidate substances and formulations. This chapter describes an ALI cell exposure assay for measuring toxicological effects, specifically cell viability and oxidative stress, resulting from exposure to aerosols containing nanoparticles.

SSCI-VIDE+ING+FRM:NOG:YSC; International audience; The present work deals with the modelling and simulation of a biogas Demo-processor for green hydrogen production via Autothermal reforming (ATR) process aimed at covering a wide span of potential applications, from fuel cells feed up to the production of pure hydrogen. The biogas ATR unit is composed of a structured catalyst support close coupled to a wall-flow filter that retain soot particles that can be formed during the ATR reaction. Modelling and simulation (CFD and FEM) were carried out to select the innovative catalyst support with promising results for the fuel processor. 3D digital sample reconstruction was performed for the selection of the appropriate porous structures commercially available for the soot filtration and furthermore, 2D CFD analysis was also used to examine flow uniformity issues due to soot trap integration downstream to the ATR. Moreover, the inherent flexibility of the model performed allowed its application in the assessment of the Demonstration plant operating in real conditions. Besides, Aspen simulation has demonstrated that the ATR process is the most promising process to hydrogen production compared to other types of reforming process.

Over the last years, several research groups have focused on developing efficient thermochemical heat storage (THS) systems, in-principle capable of being coupled with next generation high temperature Concentrated Solar Power plants. Among systems studied, the Co3O4/CoO redox system is a promising candidate. Currently, research efforts extend beyond basic level identification of promising materials to more application-oriented approaches aiming at validation of THS performance at pilot scale reactors. The present work focuses on the investigation of cobalt oxide based honeycomb structures as candidate reactors/heat exchangers to be employed for such purposes. In the evaluation conducted and presented here, cobalt oxide-based structures with different composition and geometrical characteristics were subjected to redox cycles in the temperature window between 800 and 1000°C under air flow. Basic aspects related to redox performance of each system are briefly discussed but the main focus lies on the evaluation of the segments structural stability after multi-cyclic operation. The latter is based on macroscopic visual observation and also supplemented by pre– (i.e. fresh samples) and post–characterization (i.e. after long term exposure) of extruded honeycombs via combined mercury porosimetry and SEM analysis.

In the present work we examine how recent progress at our collaborating laboratories, over various solar thermochemical technologies, can be brought to bear on the advancement of renewable resource utilization in Qatar.Specific examples of such technologies include solar water splitting for H2 production, solar CO2 splitting thermochemical energy storage in reduced metal oxides, solar cracking of CH4 for production of carbon nanoparticles and hydrogen, and production of metal nanoparticles to be employed as renewable fuel. Where feasible the potential of using locally sourced materials is stressed and particular examples are given (e.g. the use of Qatar's CaCO3). Enabling technologies over all scales (from the lab to the demonstration scale) include advanced instrumentation and testing platforms (e.g, solar simulators, solar furnaces, etc). Reactor concepts and system designs are formulated and analyzed and promising designs from the user's perspective are identified for advancing to the next level. Here we describe results and future directions from three such examples.A low energy, zero-effluent system for clean water production, employing a concentrated solar thermal aquatic stream processing module is described. The projected specific electric energy consumption of the system does not exceed 1 kWh/m3, which in fact can be largely produced by the system itself. The system can exhibit an unprecedented (>99%) clean water recovery from any aquatic stream (seawater, brines, wastewater). At the same time the salt/solids content of the aquatic stream is separated in dry-form, thus being transformed from a waste-to-be-managed into a raw material ready for further commercial exploitation. The system is based on a modular design hence it is applicable over a range of scales, from standalone applications to large scale industrial water plants as well as an add-on to existing large scale producers and/or users of water, for further recovery of water and residual solids (salts, valuable metals from brine/wastewater effluents).Production of hydrogen can be achieved via photo- and electro-chemical water splitting processes. In order for such processes to be feasible, they employ sacrificial electron donors which also bind oxygen molecule. Then, they have to be regenerated, via thermochemical reactions, and also release the oxygen. So the whole process operates in a cyclic mode, thus called water-splitting cycle. The use of solar energy for the realization of the thermochemical steps increases the overall solar-to-hydrogen efficiency. The Hybrid Sulfur Ammonia cycle, described here, uses ammonium sulfate as the sacrificial donor and a mixture of alkali-metal sulfates and pyrosulfates, which help to recover oxygen at lower temperatures and higher efficiency. We present the of thermal analysis experiments conducted for the calculation of the respective thermodynamic properties (heat capacity and enthalpy). In addition, with the use of advanced thermodynamic tools (FacTSAGE etc), and experimental thermal analysis, we completed the thermodynamic analysis, and selected the reaction temperatures in a range from 350°C to 900°C.The crucial drawback of solar energy is its intermittent character. At the same time, pollution caused by the release of CO2, mainly in power plants and cement production, results in a series of problems such as global warming and poor air quality. Thermal Energy Storage (TES) can provide an escape route for both the aforementioned problems. TES can be used in order to store heat during periods of high solar irradiation and release it during the night or periods of low activity. Carbonate systems, such as calcite and dolomite, can be utilized for TES. In this study we focus on the reversible calcination/carbonation cycle of (CaMg)CO3, because it is a very strong candidate as a high efficiency thermochemical material. Its energy density is the highest among other materials. It can be found in vast quantities in Qatar, according to its geological formation, thus can be easily used as low cost/high added value material. Furthermore, it is a non-toxic and safe material with easy separation of the phases. In addition, the cycle involves CO2 capture during the discharge stage. This ends up in both energy release and greenhouse gases elimination. So far, we have characterized thermally, chemically and morphologically local raw surface carbonates. Results show that dolomitic powder, (CaMg)CO3 from Northern Qatar and subsurface rocks have an average capacity of 6 mmol CO2/g, but sintering deactivates material significantly after 20 cycles. Currently, we are designing a potential TES process coupled to cement production. In parallel, we are investigating experimentally the available methods to enhance the capacity of the raw material and improve its stability.Present research contributes towards the solution of the Global Challenges that our societies face today, and in particular it provides access to safe and clean water and energy. These can be achieved with improved performance, energy efficiency and ease of usability.

Following the successful market introduction of diesel particulate filters (DPFs), this class of emission control devices is expanding to include functionalities, in addition to particle filtration, such as gas species oxidation and reduction to the extent that we should today refer to them as Multifunctional Reactor Separators. This trend poses many challenges for the modeling of such systems. In the present paper we address mathematical descriptions of some specific aspects of multifunctional DPFs for inclusion in comprehensive simulation tools in a physically accurate and computationally efficient manner. In particular, we study the behavior of thin, coating layers on top of the filter wall, and their effect on particle collection efficiency and pressure drop with the aid of Digital Material techniques that provided a guidance for the development of coated DPFs with added particle collection efficiency and lower pressure drop during soot loading. Soot–catalyst contact dynamics during soot oxidation by catalytic coatings was investigated with the application of a model including the distribution of different soot–catalyst contact states which is shown to be in very good agreement with the experimental data. Finally an analytical framework has been developed to describe the reactions of exhaust gas species in a DPF wall endowed both with a gas oxidation function and a reducing function (based on NH3-Selective Catalytic Reduction). The developments can be readily incorporated in DPF simulation tools, and enable the efficient and accurate simulation of multifunctional DPFs.

The hydrogen production based on the exploitation of the water splitting reaction and of solar energy on monolith type reactors is a novel and very promising process. Several trade offs between reaction efficiency and material stability appear during the operation of the process rendering necessary advanced optimization and control using appropriate mathematical models. The complexity of the geometric and operating features of the process prevents from the use of a general model for the optimization studies so a model splitting in several size scales procedure is proposed. It is shown that in case of silicon carbide as monolith material the one dimensional single channel model is the most appropriate to be used for the process operation optimization studies. The above general principles are described in detail in the present paper to shed light to the particular modeling problem with the emphasis given in the work performed in our laboratory.

The present work describes the realisation and successful test operation of a 100 kW pilot plant for two-step solar thermo-chemical water splitting on a solar tower at the Plataforma Solar de Almeria, which aims at the demonstration of the feasibility of the process on a solar tower platform under real conditions. The process applies multi-valent iron based mixed metal oxides as reactive species which are coated on honeycomb absorbers inside a receiver–reactor. By the introduction of a two-chamber reactor it is possible to run both process concepts in parallel and thus, the hydrogen production process in a quasi-continuous mode. In summer 2008 an exhaustive thermal qualification of the pilot plant took place, using uncoated ceramic honeycombs as absorbers. Some main aspects of these tests were the development and validation of operational and measurement strategy, the gaining of knowledge on the dynamics of the system, in particular during thermal cycling, the determination of the controllability of the whole system, and the validation of practicability of the control concept. The thermal tests enabled to improve, to refine and finally to prove the process strategy and showed the feasibility of the control concept implemented. It could be shown that rapid changeover between the modules is a central benefit for the performance of the process. In November of 2008 the absorber was replaced and honeycombs coated with redox material were inserted. This allowed carrying out tests of hydrogen production by water splitting. Several hydrogen production cycles and metal oxide reduction cycles could be run without problems. Significant concentrations of hydrogen were produced with a conversion of steam of up to 30%.

The present work summarizes the recent activities of our laboratory in the field of solar-aided hydrogen production with structured monolithic solar reactors. This reactor concept, “transferred” from the well-known automobile exhaust catalytic after-treatment systems, employs ceramic supports optimized to absorb effectively solar radiation and develop sufficiently high temperatures, that are coated with active materials capable to perform/catalyze a variety of “solar-aided” reactions for the production of hydrogen such as water splitting or natural gas reforming. Our work evolves in an integrated approach starting from the synthesis of active powders tailored to particular hydrogen production reactions, their deposition upon porous absorbers, testing of relevant properties of merit such as thermomechanical stability and hydrogen yield and finally to the design, operation simulation and performance optimization of structured monolithic solar hydrogen production reactors. This approach, among other things, has culminated to the world's first closed, solar-thermochemical cycle in operation that is capable of continuous hydrogen production employing entirely renewable and abundant energy sources and raw materials – solar energy and water, respectively – without any CO 2 emissions and holds, thus, a significant potential for large-scale, emissions-free hydrogen production, particularly for regions of the world that lack indigenous resources but are endowed with ample solar energy.

The novel monolithic-type electrochemical promoted reactor (MEPR), filled with thick Rh and Pt coated films on thin yttria-stabilized zirconia (YSZ) plates, has been tested in simulated and real automotive exhaust gas. Ethylene oxidation and NO reduction by C2H4 in presence of oxygen were investigated in laboratory scale while the automotive bench testing was performed in the exhaust of a diesel engine. In all cases electropromotion was achieved, an advance which in addition to their compact and simple design, makes electropromoted units quite promising for automotive exhaust pollution control.

In recent years advanced computational tools of diesel particulate &lter (DPF) regeneration have been developed to assist in the systematic and cost-e5ective optimization of next generation particulate trap systems. In the present study, we employ a previously validated, state-of-the-art multichannel DPF simulator to study the regeneration process over the entire spatial domain of the &lter. Particular attention is placed on identifying the e5ect of inlet cones and boundary conditions, &lter can insulation and the dynamics of “hot spots” induced by localized external energy deposition. Lateral heat losses through the insulation and the periphery of the &lter can, as captured by the magnitude of the Nusselt number,Nu, are detrimental to the e5ectiveness of the regeneration process. A &lter can Nu number less than 10 and preferably less than 5 is a good design target for high regeneration e=ciency. For the case studied, insulation of the inlet cones can lead to a gain of 30% in regeneration e=ciency by eliminating radial temperature gradients at the inlet &lter face. The multichannel simulator provides an instructive illustration of the well-appreciated e5ects of localized hot spot on &lter regeneration: hot spots play a more signi&cant role (spread over) when located near the entrance of the &lter. ? 2003 Elsevier Ltd. All rights reserved.

Particulate filter systems will most likely be required for compliance of diesel-powered vehicles and equipment to future emission legislation. The major issue with such systems is that their reliable and cost-effective regeneration (through oxidation of the collected soot particles) is not currently possible under all engine operating conditions without additional external thermal energy. In the present work we exploit the autothermal properties of the reverse flow reactor and study its application for the improvement of the regeneration process of diesel particulate filters. The reciprocating flow regeneration of soot filters is investigated with the aid of a mathematical model for the regeneration process, after the model has been assessed against conventional experimental regeneration data. The numerical results confirm the capability of the new technique to provide a clean filter where conventional regeneration fails. In this way the operating limits of current regeneration techniques (thermal or catalyst-assisted) can be extended substantially, and the stage is set for the construction of an industrial prototype.

The EU emission standards for new rail Diesel engines are becoming even more stringent. EGR and SCR technologies can both be used to reduce NOx emissions; however, the use of EGR is usually accompanied by an increase in PM emissions and may require a DPF. On the other hand, the use of SCR requires on-board storage of urea. Thus, it is necessary to study these trade-offs in order to understand how these technologies can best be used in rail applications to meet new emission standards. The present study assesses the application of these technologies in Diesel railcars on a quantitative basis using one and three dimensional numerical simulation tools. In particular, the study considers a 560 kW railcar engine with the use of either EGR or SCR based solutions for NOx reduction. The NOx and PM emissions performances are evaluated over the C1 homologation cycle. The simulation results indicate that either EGR or SCR based solutions can be used to achieve Stage IIIB NOx limits for the 560 kW engine, with an acceptable trade-off regarding BSFC in the case of EGR solutions. In the case of EGR, though, a DPF is necessary to meet Stage IIIB PM limits. Furthermore, SCR based solutions have the potential to go beyond the Stage IIIB NOx limit by scaling up the size of the SCR device and the on-board urea storage. Copyright © 2013 SAE International.

HycycleS was a cooperation of nine European partners and further non-European partners and aimed at the qualification and enhancement of materials and components for key steps of solar and nuclear powered thermochemical cycles for hydrogen generation from water. The focus of HycycleS was the decomposition of sulphuric acid (H2SO4) which is the central step of the sulphur-based family of those processes. Emphasis was put on materials and components for H2SO4 evaporation, decomposition, and sulphur dioxide separation. The suitability of materials and components was demonstrated by decomposing H2SO4 and separating its decomposition products in scalable prototypes. Silicon Carbide (SiC) turned out as the material of choice for the components facing the most corrosive environment of the process: the sulphuric acid evaporator and decomposer. Candidate catalysts for the high temperature reduction of sulphur trioxide have been screened and analysed. Cr-Fe mixed oxide (Fe 0.7Cr1.3O3) was the most promising material among the ones examined. Based on the use of the highlighted construction and catalyst materials prototype decomposers have been developed and tested. The successful fabrication and testing of a large size heat exchanger/reactor prototype composed of SiC plates shows promise with respect to its use for H2SO4 decomposition in the SI and HyS cycle. A solar specific decomposer prototype was developed, realised and successfully tested on sun in a solar furnace. A novel approach of using dense oxygen transport membranes, made from complex ceramics, for oxygen removal from the H 2SO4 decomposition product in order to shift the equilibrium in favour of increased decomposition was investigated. The membranes stability and suitability for carrying out this separation was investigated experimentally. Parallel to this, a conventional oxygen separator, a low-temperature wet scrubbing system, was investigated as well. Scale-up scenarios of components and of the process were addressed. Copyright © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Diesel Low Temperature Combustion (LTC) technologies for passenger cars are considered to be potentially beneficial due to low soot particulate and NOx emissions. However, it is anticipated that they will not remove the necessity of the exhaust emission control systems and especially the Diesel Particualte filters (DPFs). Moreover, LTC mode of engine operation demands tailored emission control systems that would address issues like the low NOx to soot ratio, the elevated HC and CO concentration etc. In this work, the development of a novel MultiFunctional Reactor (MFR) for the diesel engine exhaust is presented. The aim was to build a system that would have increased catalytic direct and indirect (NO2-assisted) soot oxidation activity taking also advantage of thermal heat recovery (Konstandopoulos & Kostoglou, 1999) to minimize, the associated to the filter regeneration, fuel penalty. The MFR incorporates a metal mixed oxide catalyst (MOC) and barium oxide (BaO) synthesized and deposited via an aerosol route, and a noble metal (Pt) applied via a traditional wet-chemistry technique (Konstandopoulos et al., 2008). MOC was used to enhance the direct soot oxidation rate, while Pt was used for the enhancement of the indirect soot oxidation rate and CO and HC conversion. BaO was included to improve the local availability of NO2 and thus increase the soot oxidation rate. The combination of aerosol and wet chemistry techniques enabled the optimal distribution of the different catalytic functionalities on the filter substrate wall. Evaluation of the catalysts was conducted at the small scale (catalyst coated small filter samples), with respect to their filtration efficiency, soot loading behaviour and soot oxidation activity at the engine test cell bench and was compared samples obtained from a catalyzed wall-flow Reference Diesel Particulate Filter (Reference DPF). At the small scale the catalyzed filters demonstrated increased “initial” filtration efficiency compared to the reference DPF. The incorporation of Pt enhanced the indirect soot oxidation activity as well as the HC and CO conversion, with the type of the washcoat and the amount of Pt playing an important role. Addition of BaO has positive impact on the indirect soot oxidation, while the combination of aerosol and wet-chemistry techniques (for the Pt and the washcoat) enabled the production of multifunctional coatings with enhanced direct as well as indirect soot oxidation activity. Based on the obtained results a full scale prototype MFR was built. The performance of this prototype was examined with respect to its heat recovery capability and to the soot loading and regeneration behaviour. At the full-scale (prototype MFR) integration of the filtration function and heat exchange was achieved, without the use of an external heat exchanger. The MFR prototype demonstrated significant internal heat recovery capability. On the basis of soot loading and regeneration behaviour, the pressure drop of the MFR during soot loading was at comparable level with the pressure drop of the Reference DPF and even smaller after a certain soot mass load. More significantly, it demonstrated increased soot oxidation rate with respect to the Reference DPF in the temperature area between 450 and 550C (up to 4 times, Figure 1).

As diesel emissions regulations are becoming more stringent, diesel particulate filters (DPFs) have become possibly the most important and complex diesel emission control device. A traditional design of experiments approach becomes very time consuming and costly if one wants to address DPF design, system integration, regeneration control strategy optimization and ash ageing assessment, due to the very large number of tests needed. The application of simulation tools provides a promising alternative and hence simulation is increasingly being used for the design of exhaust emission control systems. In a DPF many coupled physico-chemical phenomena occur over widely disparate spatial and temporal scales and the simulation approach should account for and exploit these features. This becomes possible with the introduction of certain defensible assumptions and/or simplifications to arrive at an accurate but computationally tractable DPF simulation approach, for the needs of industrial users. The present chapter summarizes the current state of the science and technology of DPF simulation, from the Aerosol & Particle Technology Laboratory (APTL), addressing consistent and rigorous refinements in a number of areas including: the aerodynamics at the filter and channel inlet, flow, filtration and reaction phenomena at the DPF material microstructure scale, and in coupling/interfacing DPF simulation with three-dimensional (3D) Computational Fluid Dynamics (CFD) codes. Experimental results are cited where appropriate, to re-enforce/validate the points brought forward by the simulation approach.

A very promising method for the conversion and storage of solar energy into a fuel is the dissociation of water to oxygen and hydrogen, carried out via a two-step process using metal oxide redox systems such as mixed iron oxides, coated upon multi-channeled honeycomb ceramic supports capable of absorbing solar irradiation, in a configuration similar to that encountered in automobile exhaust catalytic converters. With this configuration, the whole process can be carried out in a single solar energy converter, the process temperature can be significantly lowered compared to other thermo-chemical cycles and the re-combination of oxygen and hydrogen is prevented by fixing the oxygen in the metal oxide. For the realization of the integrated concept, research work proceeded in three parallel directions: synthesis of active redox systems, manufacture of ceramic honeycomb supports and manufacture, testing and optimization of operating conditions of a thermochemical solar receiver-reactor. The receiver-reactor has been developed and installed in the solar furnace in Cologne, Germany. It was proven that solar hydrogen production is feasible by this process demonstrating that multi cycling of the process was possible in principle.Copyright © 2005 by ASME

The present work proposes the exploitation of solar energy for the dissociation of water and production of hydrogen via an integrated thermo-chemical reactor/receiver system. The basic idea is the use of multi-channelled honeycomb ceramic supports coated with active redox reagent powders, in a configuration similar to that encountered in automobile exhaust catalytic aftertreatment. Iron-oxide-based redox materials were synthesized, capable to operate under a complete redox cycle: they could take oxygen from water producing pure hydrogen at reasonably low temperatures (800 � C) and could be regenerated at temperatures below 1300 � C. Ceramic honeycombs capable of achieving temperatures in that range when heated by concentrated solar radiation were manufactured and incorporated in a dedicated solar receiver/reactor. The operating conditions of the solar reactor were optimised to achieve adjustable, uniform temperatures up to 1300 � C throughout the honeycomb, making thus feasible the operation of the complete cycle by a single solar energy converter. � 2005 Elsevier Ltd. All rights reserved.

Diesel Particulate Filters (DPFs) need to be periodically regenerated in order to achieve efficient and safe vehicle operation. Under typical diesel exhaust conditions, this invariably requires the raising of the exhaust gas temperature by active means,. up to the point that particulate (soot) oxidation can be self-sustained in the filter. In the present work the development path of an advanced catalytic filter technology is presented. Full scale optimized Catalytic Diesel Particulate Filters (CDPFs) are tested in the exhaust of a light-duty modern diesel engine in line with a Diesel Oxidation Catalyst (DOC). The management of the DOC-CDPF emission control system is facilitated by a virtual soot sensor in order to ensure energy-efficient operation of the emission control system.

The DEXA Cluster consisted of three closely interlinked projects. In 2003 the DEXA Cluster concluded by demonstrating the successful development of critical technologies for Diesel exhaust particulate after-treatment, without adverse effects on NO[x] emissions and maintaining the fuel economy advantages of the Diesel engine well beyond the EURO IV (2000) emission standards horizon. In the present paper the most important results of the DEXA Cluster projects in the demonstration of advanced particulate control technologies, the development of a simulation toolkit for the design of diesel exhaust after-treatment systems and the development of novel particulate characterization methodologies, are presented. The motivation for the DEXA Cluster research was to increase the market competitiveness of diesel engine powertrains for passenger cars worldwide, and to accelerate the adoption of particulate control technology.

A major challenge in the development of diesel filter systems is the selection of the appropriate filter medium in terms of its geometric configuration (cell density, wall thickness) and its physical properties (porosity, pore size). This selection aims to achieve minimization of the filter pressure drop as well as more efficient filter regeneration. The aim of the present work is to provide engineering criteria to support the design and selection of suitably sized wall-flow monolithic filters for diesel particulate control. The approach followed in the present paper is to employ a comprehensive, experimentally validated mathematical framework taking into account the effects of filter structure (cell density, filter dimensions, wall thickness, permeability), soot cake microstructure and its evolution under varying exhaust flow conditions, as well as ash accumulation, in order to derive optimal configurations and sizing criteria of monolithic filters that can be used for specific applications. A major result concerns the derivation of nomographs giving the optimum cell density for honeycomb filters under the combined constraints of given filter volume, exhaust flow, temperature, as well as different soot and ash loadings inside the filter. These nomographs are expected to facilitate the task of selection and reliable life-cycle deployment of diesel particulate filters.

In the present work a practice for conducting experiments and analyzing the fundamental descriptors of Diesel Particulate Filter (DPF) flow resistance behavior is described. The recommended practice addresses each of the following areas: definition of flow resistance descriptors, filter geometrical characteristics, experimental setup and data analysis methods. The sources of errors in each area are identified and a sensitivity analysis is performed. Finally, the recommended practice is applied to several filter materials and configurations tested in the laboratory to determine objectively a set of flow resistance descriptors (namely the filter wall permeability, inlet/outlet loss coefficient) and their error bars. It is expected that application of the recommended practice for the determination of the flow resistance descriptors of DPFs will lead to better quality control procedures and meaningful comparisons of experimental data collected at different laboratories. As a useful outcome of the suggested practice a permeability-pore structure correlation extending over 5 orders of magnitude for cordierite and SiC porous media is obtained and the effect of catalyst coating on the filter flow resistance is analyzed.

In recent years advanced computational tools of Diesel Particulate Filter (DPF) regeneration have been developed to assist in the systematic and cost-effective optimization of next generation particulate trap systems. Inthe present study we employ an experimentally validated, state-of-the-art multichannel DPF simulator to study the regeneration process over the entire spatial domain of the filter. Particular attention is placed on identifying the effect of inlet cones and boundary conditions, filter can insulation and the dynamics of "hot spots" induced by localized external energy deposition. Comparison of the simulator output to experiment establishes its utility for describing the thermal history of the entire filter during regeneration. For effective regeneration it is recommended to maintain the filter can Nusselt number at less than 5. For the case studied, insulation of the inlet cones can lead to a gain of 30% in regeneration efficiency by eliminating radial temperature gradients at the inlet filter face. A model of ash transport and deposition in the filter channels has been derived, opening the door to the mechanistic description of filter aging by ash accumulation. In this way a number of variables and their effect on the soot oxidation potential of each regeneration technology can be assessed. In addition, filter thermo-mechanical behavior can be now analyzed by coupling the thermal history of the filter to a stress analysis code. In the present study, different filter technologies (catalyzed and NO 2 assisted), which have been assessed experimentally in the exhaust of a passenger car diesel engine, are analyzed comprehensively with the suite of the developed simulation tools. Based on these comparisons a ranking of filter material technologies with respect to their soot oxidation potential is obtained providing a means for their systematic improvement.

In the present work we apply a computational simulation framework developed for square-cell shaped honeycomb Diesel Particulate Filters to study the filtration, pressure drop and soot oxidation characteristics of recently developed triangular-cell-shaped, high porosity wall-flow filters. Emphasis is placed on the evaluation of the applicability and adaptation of the previously developed models to the case of triangular channels. To this end Computational Fluid Dynamics, asymptotic analysis, multichannel and "unit-cell" calculations are employed to analyze filter behavior and the results are shown to compare very well to experiments available in the literature.

A computational lumped parameter model (MTU-Filter- Lumped) was developed to describe the performance of diesel particulate filters (DPFs) during loading and regeneration processes. The model was formulated combining three major sub-models: a filtration model, a pressure drop model, and a mass and an energy balance equation for the total filter volume. The first two submodels have been widely validated in the literature, while the third sub-model is introduced and combined with the first two sub-models in the present study. The three sub-models combined can give a full description of diesel particulate filter behavior during loading and regeneration processes, which was the objective of the present work. The total combined lumped parameter model was calibrated using experimental data from the literature covering a range of experimental conditions, including different catalytic regeneration means and engine- operating conditions. The model predictions showed very good agreement with the experimental data in terms of pressure drop across the filter, mass retained in the filter, and filter temperature. A diesel particulate filter system was selected to illustrate the control application of the lumped model equations. This system involves a diesel particulate filter for the collection and oxidation of the engine out particulate matter emissions, and the injection of hydrocarbons upstream of an oxidation catalytic converter (OCC) in order to raise the exhaust gas temperature and in turn achieve filter regeneration. Two model-based control strategies were developed aiming to minimize the fuel penalty of the regeneration process described above.

In order to study the various health influencing parameters related to particulate as well as to gas-phase pollutants emitted by Diesel engine exhaust, there is an urgent need for appropriate sampling devices and methods for cell exposure studies and associated biological and toxicological tests. In a previous paper [1], a specific concept for a cell culture exposure chamber was introduced to allow the uniform exposure of cell cultures to diesel aerosols. In the present work, this cell culture exposure chamber is evaluated and characterized with state-of-the-art nanoparticles measurement instrumentation to assess the local deposition of soot aggregates on the cell cultures and any losses due to particle deposition on the cell culture exposure chamber walls, and in addition an upgraded Multiculture Exposure Chamber (MEC) for in vitro continuous flow cell exposure tests is introduced with improved, compared to the previous version, features. Analysis and design of the MEC employs CFD and true to geometry representations of soot particle aggregates.

The European FP7 project HycycleS focuses on providing detailed solutions for the design of specific key components for sulphur-based thermochemical cycles for hydrogen production. The key components necessary for the high temperature part of those processes, the thermal decomposition of H2SO4, are a compact heat exchanger for SO3 decomposition for operation by solar and nuclear heat, a receiver-reactor for solar H2SO4 decomposition, and membranes as product separator and as promoter of the SO3 decomposition. Silicon carbide has been identified as the preferred construction material. Its stability is tested at high temperature and in a highly corrosive atmosphere. Another focus is catalyst materials for the reduction of SO3. Requirement specifications were set up as basis for design and sizing of the intended prototypes. Rigs for corrosion tests, catalyst tests and selectivity of separation membranes have been designed, built and completed. Prototypes of the mentioned components have been designed and tested.

Renewable hydrogen produced using solar energy to split water is the energy fuel of the future. Accelerated innovation in both major domains of solar energy (photovoltaics and concentrated solar power) has resulted in the rapid fall of the solar electricity price, opening the route to a number of practical applications using solar H2. Referring to several examples as well as to new technologies, this article provides insight into a crucial technology for our common future.

Advanced Diesel engine technologies employ Low Temperature Combustion (LTC) to offer substantial advantages to the reduction of NOx and Particulate Matter (PM) emissions but will most probably not succeed to make the application of Diesel Particulate Filters (DPFs) dispensable in the future. In this work the research and development efforts for the realization of a Multi-Functional catalyst Reactor (MFR) for the exhaust of the upcoming diesel engines is presented. This work is based on recent advances in catalytic nano-structured materials synthesis and coating techniques. Different gaseous and soot oxidation catalytic functionalities have been carefully distributed in the filter substrate microstructure and a novel filter design has been applied to enable internal heat recovery capability by the implementation of heat exchange between the outlet and the inlet to the filter flow paths. MFR prototypes, suitable for the abatement of both gaseous and PM emissions of the LTC engine operation, have been realized. The evaluation results of the MFR performance under both conventional and advanced combustion engine operating conditions are presented.

The effect of the use of a manganese-copper fuel additive with a Corning EX-47 particulate trap on heavy-duty diesel emissions has been investigated

The research on health effects of soot particles has demonstrated their toxic impact on humans, especially for the smallest ones that can pass through the lungs into the bloodstream and be transferred to other parts of the body. Since the Euro 5b regulation, the total particle number (PN) at the exhaust is limited, but the associated protocol developed by the Particle Measurement Program (PMP) group defined a counting efficiency at the 23 nm cut-off particle diameter to avoid measurement artefacts. Recent studies have demonstrated that the last generation Euro 6 engines can emit as many particles in the range 10-23 nm as beyond 23 nm. The SUREAL-23 project (Understanding, Measuring and RegulatingSub-23nm Particle Emissions from Direct Injection Engines IncludingRealDriving Conditions), funded by Horizon 2020 EU-program, aims to develop sampling, conditioning and measuring instruments and associated methodologies to extend the existing protocol down to at least 10 nm. This measurement setup was evaluated on various light duty direct injection platforms. This communication focuses on a gasoline-DI vehicle with a Euro 6b engine. Tests were conducted on multiple operating conditions (moderate and aggressive driving cycles, hot and cold starts, and several fuel and lubricant formulations). Sampling and conditioning were done with a two-stage dilution system, with a built-in catalytic stripper. The prototype instruments have been compared to commercial reference soot particle analyzers (TSI CPC, Horiba MEXA-2000 SPCS and Cambustion DMS500). A good consistency between all the measurements was demonstrated, with a satisfactory repeatability and robustness of the proposed measurement setup and of the associated methodology. An on-board version of the proposed setup is currently being developed to allow PN measurement in Real Driving Emissions (RDE) conditions.

The present work relates to the investigation of the basic oxidation characteristics of iron and aluminium nanoparticles as well as the feasibility of their combustion under both Internal Combustion Engine (ICE)-like and real engine conditions. Based on a series of proof-of-concept experiments, combustion was found to be feasible taking place in a controllable way and bearing similarities to the respective case of conventional fuels. These studies were complimented by relevant in-situ and ex-situ/post-analysis, in order to elaborate the fundamental phenomena occurring during combustion as well as the extent and ‘quality’ of the process. The oxidation mechanisms of the two metallic fuels appear different and -as expected- the energy release during combustion of aluminium is significantly higher than that released in the case of iron. The peak gas temperatures recorded during combustion of iron under engine-like and real engine conditions indicate that the NOx formation threshold is not reached. Combustion of aluminium yields substantially higher peak combustion temperatures and thus it is likely that is accompanied by NOx emissions. In addition, the experimental results provided indication that the approach of Exhaust Gas Recirculation (EGR) could be an efficient means of controlling the combustion process.