EC Systems Research Articles

Parametric analysis of hybrid elastocaloric – CO2 cooling system

This study examines the potential application of elastocaloric refrigeration (eC) technology for the subcooling of CO2 in transcritical single-stage refrigeration cycles. Elastocaloric refrigeration, a solid-state refrigeration technology, possesses significant untapped potential due to its environmentally friendly characteristics, primarily its lack of harmful operational fluids. However, its direct stand-alone application has been limited due to the relatively small temperature spans produced by current proof-of-concept elastocaloric devices. Efforts of the scientific community have focused on extending the temperature difference that eC systems can provide, while this work offers an alternative to that challenge, offering an application solution for the current state of technology. The study proposes for the first-time a unique integration of eC technology and CO2 cooling systems, aiming to capitalise on the respective weaknesses of these technologies and transform them into strengths. In the proposed solution, an eC device operates as an external agent to subcool CO2, with the objective of enhancing the energy performance of the refrigeration system. This concept is motivated by the recent advancements in CO2 cooling systems and the growing recognition of subcooling as a promising method to boost the performance of such systems. The hybrid system’s performance was evaluated across various ambient temperatures, ranging from 20 °C to 35 °C, and at an evaporating level of −15 °C. It is evaluated by means of a calculation model based on the data obtained experimentally from an elastocaloric regenerator and an experimental CO2 plant. The system‘s energy efficiency was analysed in comparison to a non-subcooled CO2 cycle, and a third cycle comprising both eC subcooling and an expander for energy recovery from the expansion process. The results demonstrated a considerable increase in the coefficient of performance (COP) with the use of eC subcooling: increments of 2.7 % at 20 °C, 4.5 % at 25 °C, 9.6 % at 30 °C and 13.1 % at 35 °C, where more significant increments were observed at higher ambient temperatures. The eC Subcooler with expander reaches increments of 7.5 %, 11.1 %, 18.1 % and 22.2 % respectively. Additionally, the eC subcooler allowed a reduction in the optimum gas-cooler pressure by up to 5 bar at the highest environment temperature. Despite these promising results, the study underscores the necessity for further optimisation and improvement of elastocaloric devices. Additionally, it emphasizes the importance of energy recovery strategies from the expansion process in transcritical CO2 cooling system.

Probabilistic Techno-Economic Assessment of Medium-Scale Photoelectrochemical Fuel Generation Plants.

Photoelectrochemical (PEC) systems are promising approaches for sustainable fuel processing. PEC devices, like conventional photovoltaic-electrolyzer (PV-EC) systems, utilize solar energy for splitting water into hydrogen and oxygen. Contrary to PV-EC systems, PEC devices integrate the photoabsorber, the ionic membrane, and the catalysts into a single reactor. This integration of elements potentially makes PEC systems simpler in design, increases efficiency, offers a cost advantage, and allows for implementation with higher flexibility in use. We present a detailed techno-economic evaluation of PEC systems with three different device designs. We combine a system-level techno-economic analysis based on physical performance models (including degradation) with stochastic methods for uncertainty assessments, also considering the use of PV and EC learning curves for future cost scenarios. For hydrogen, we assess different PEC device design options (utilizing liquid or water vapor as reactant) and compare them to conventional PV-EC systems (anion or cation exchange). We show that in the current scenario, PEC systems (with a levelized cost of hydrogen of 6.32 $/kgH2 ) located in southern Spain are not yet competitive, operating at 64% higher costs than the PV-driven anion exchange EC systems. Our analysis indicates that PEC plants' material and size are the most significant factors affecting hydrogen costs. PEC designs operating with water vapor are the most economical designs, with the potential to cost about 10% less than PV-EC systems and to reach a 2 $/kgH2 target by 2040. If a sunlight concentrator is incorporated, the PEC-produced hydrogen cost is significantly lower (3.59 $/kgH2 in the current scenario). Versions of the concentrated PEC system that incorporate reversible operation and CO2 reduction indicate a levelized cost of storage of 0.2803 $/kWh for the former and a levelized cost of CO of 0.546 $/kgCO for the latter. These findings demonstrate the competitiveness and viability of (concentrated) PEC systems and their versatile use cases. Our study shows the potential of PEC devices and systems for hydrogen production (current and future potential), storage applications, and CO production, thereby highlighting the importance of sustainable and cost-effective design considerations for future advancements in technology development in this field.

Probing iodide/iodonium salt interactions with single-walled carbon nanotubes for resilient electrochemical capacitor

Self-standing films from single-walled carbon nanotubes (SWCNTs) were successfully used as electrochemical capacitors’ (ECs) electrode material, which exhibited state-of-the-art characteristics. The surface of SWCNTs was modified by iodonium salt molecules that substantially and permanently improved their electrical conductivity. The addition of pyridinium iodine chloride salt (IPyCl) quadrupled the value of the electrical conductivity of the SWCNT film, which reached values as high as 1022 S cm−1. Subsequently, the electrochemical performance of the newly designed self-standing SWCNTs with deposited IPyCl in aqueous neutral 1 M Li2SO4 and redox-active 1 M KI electrolytes was thoroughly analysed. Because redox activity of iodine species was observed mainly on the positive electrode, activated carbon with a developed surface area was used as a negative electrode to balance the faradaic charge. Due to the notable stability of iodonium salt dopant (instead of labile halogen-containing compounds typically used for SWCNT doping), robust charge/discharge performance of EC was demonstrated (> 10 000 cycles) in Li2SO4 electrolyte. Moreover, a significant improvement of capacitor metrics (from 49 to 75 F g−1) was obtained when electrodes modified by previously unexplored iodonium salt were utilized in 1 M KI electrolyte. Extensive analysis of the obtained data led to the elucidation of the doping mechanism responsible for the aforementioned achievements. The novel SWCNT-based electrodes enhanced with iodonium salt are auspicious materials, which can be used to build EC systems of appreciable capacitance.

MR.D.I.Y. “the Malaysian sweetheart”

Learning outcomes Upon completion, successful students will be able to examine the importance of digitalisation as a competitive tool in business management; use a suitable theory to justify the need for an organisation to engage in e-commerce; develop suitable strategies/solutions to challenges faced by a business organisation in the world of digitalisation of business; explain the way data analytics and digitalisation can affect business strategies and marketing functions; and identify and explain various considerations in the internationalisation of business. Case overview/synopsis MR.D.I.Y. “The Malaysian Sweetheart” is a case about a home improvement company that has transformed itself from a regular hardware shop into a favourite home improvement retailer in Malaysia. The case looked at the influence of e-commerce and digital transformation marks a rethinking of how an organisation uses technology, people and processes in pursuit of new business models and new revenue streams, driven by changes in customer expectations around products and services. Such transformation has indeed created opportunities and challenges for business organisation throughout the globe in their pursuit of staying competitive for MR.D.I.Y. even though they are considered the largest home improvement retailer in Malaysia. The case also introduces the students to the Uses and Gratification Theory that underpins the e-commerce business model. The management of the company is concerned about its future given the rising competition and gloomy economic conditions. Complexity academic level The target group for this case is undergraduate students. Specifically, it is suitable for those in the field of Entrepreneurship taking e-commerce/small business management/entrepreneurship courses. The main purpose of this case study is to assist students in critically examining how a small business evolved from a tiny neighbourhood shop to become a household name at the national level and eventually emerged as the largest home improvement company locally and abroad. Specifically, the case can be applied to topics like Retailing in Electronic Commerce, Innovative EC Systems, Social Commerce and Launching an Online Business, which all are related to the courses on E-Commerce, and this case is also suitable to any other contemporary business management module. Additionally, educators can use this teaching case as a tool in an executive programme for senior, middle and lower managers to shape their thoughts and attitudes toward managing a contemporary retailing business. With this case, it is hoped that students would be able to understand and decide wisely if they encounter similar circumstances in the future. Supplementary material Teaching notes are available for educators only. Subject code CSS 3: Entrepreneurship.

Lessons from the frontline: The value of emergency care processes and data to pandemic responses across the Pacific region

BackgroundEmergency care (EC) addresses the needs of patients with acute illness and injury, and has fulfilled a critical function during the COVID-19 pandemic. ‘Processes’ (e.g. triage) and ‘data’ (e.g. surveillance) have been nominated as essential building blocks for EC systems. This qualitative research sought to explore the impact of the pandemic on EC clinicians across the Pacific region, including the contribution of EC building blocks to effective responses.MethodsThe study was conducted in three phases, with data obtained from online support forums, key informant interviews and focus group discussions. There were 116 participants from more than 14 Pacific Island Countries and Territories. A phenomenological approach was adopted, incorporating inductive and deductive methods. The deductive thematic analysis utilised previously identified building blocks for Pacific EC. This paper summarises findings for the building blocks of ‘processes’ and ‘data’.FindingsEstablishing triage and screening capacity, aimed at assessing urgency and transmission risk respectively, were priorities for EC clinicians. Enablers included support from senior hospital leaders, previous disaster experience and consistent guidelines. The introduction of efficient patient flow processes, such as streaming, proved valuable to emergency departments, and checklists and simulation were useful implementation strategies. Some response measures impacted negatively on non-COVID patients, and proactive approaches were required to maintain ‘business as usual’. The pandemic also highlighted the value of surveillance and performance data.InterpretationDeveloping effective processes for triage, screening and streaming, among other areas, was critical to an effective EC response. Beyond the pandemic, strengthening processes and data management capacity will build resilience in EC systems.FundingPhases 1 and 2A of this study were part of an Epidemic Ethics/World Health Organization (WHO) initiative, supported by Foreign, Commonwealth and Development Office/Wellcome Grant 214711/Z/18/Z. Co-funding for this research was received from the Australasian College for Emergency Medicine Foundation via an International Development Fund Grant.

ElastoCaloric (eC) Cooling: recent studies and preliminary results on materials and devices

Refrigeration is a process aimed at lowering the temperature of an environment compared to the outside temperature. It has always played a fundamental role in modern industry: food, for the preservation of food; in the air conditioning of buildings, to make them habitable and even in the field of medicine and biology, for the preservation of samples and particular therapies. Today refrigeration systems, are responsible for about 17% of the world's electricity consumption. Therefore, the scientific community is researching solid-state refrigeration, which is 50% more efficient than vapour compression systems. Solid-state refrigeration is based on some materials' caloric effect, which can release or absorb latent heat when subjected to an external field (magnetic, electric, pressure or strain) release. Elastocaloric Refrigeration is one of the most minor explored frontiers, unlike magnetocaloric and electro-caloric systems. Some preliminary studies confirm that the eC systems have the advantage of being able to decrease the intensity of the external field (with a relative increase of the COP). In this work, a review on Ec systems is carried out, with particular attention to the description of the properties of the materials used, the various types of stress application. The results have been presented in terms of temperature, entropy, latent heat and COP.

DEMO tritium breeding performances with different in-vessel components configurations

This article presents a global study of the tritium breeding performances in DEMO for the two breeding blanket concepts helium-cooled pebble bed (HCPB) and water-cooled lithium lead (WCLL). In order to consider the impact of cut-outs in the breeding blanket to integrated plasma limiters and auxiliary systems a set of 22.5° sector models was elaborated for diverse geometry configurations. The cut-outs in the breeder blankets were implemented making use of simplified CAD models for limiters (central inboard, upper, equatorial mid plane and equatorial lower limits) as well as for EC and NBI systems. These models were converted into the MCNP geometry representations making use of SuperMC code. The TBR calculations were performed with MCNP code for all geometry models. Interference effects due to non-symmetric distribution of limiters and auxiliary systems around the torus are shown to be negligible making use of a dedicated 360° model. Therefore the total TBR can be calculated considering the separate results regarding the impact of the different In-Vessel Components (IVCs) included in the 22.5° models. The TBR decrease due to the allocation of all currently considered limiters and auxiliary systems is ∼11% and ∼10% for the HCPB and the WCLL blanket respectively. Depending on the TBRtarget value adopted in the DEMO project (assumed range being 1.02–1.05) the required TBR can vary from TBRreq = 1.13÷1.16 accounting for the impact of the integration of limiters and auxiliary systems.

A Pacific needs analysis model: a proposed methodology for assessing the needs of facility-based emergency care in the Pacific region

BackgroundEmergency care (EC) describes team-based, multidisciplinary clinical service provision, advocacy and health systems strengthening to address all urgent aspects of illness and injury for all people. In order to improve facility-based EC delivery, a structured framework is necessary to outline current capacity and future needs. This paper draws on examples of EC Needs Assessments performed at the national hospitals of three different Pacific Island Countries (PICs), to describe the development, implementation and validation of a structured assessment tool and methodological approach to conducting an EC Needs Assessment in the Pacific region.MethodsThis is a retrospective, descriptive analysis of the development of the Pacific Emergency Care Assessment (PECA) table using patient-focused principles within an EC systems framework. Tool implementation occurred through observation, literature review and interviews using a strengths-based, action-research and ethnographic methodological approach in Timor-Leste, Kiribati and the Solomon Islands. The 2014 Solomon Islands EC Needs Assessment provides the main context to illustrate and discuss the overall conduct, feasibility, validity and reliability of the PECA tool and methodological approach.ResultsIn each site, the methodological implementation enabled completion of both the PECA table and comprehensive report within approximately 6 weeks of first arriving in country. Reports synthesising findings, recommendations, priority action areas and strategies were distributed widely amongst stakeholders. Examples illustrate Face and Content, Construct and Catalytic validity, including subsequent process and infrastructure improvements triggered by the EC Needs Assessment in each site. Triangulation of information and consistency of use over time enhanced reliability of the PECA tool.Compared to other EC assessment models, the Pacific approach enabled rich data on capacity and real-life function of EC facilities. The qualitative, strengths-based method engenders long-term partnerships and positive action, but takes time and requires tailoring to a specific site.ConclusionIn PICs and other global contexts where EC resources are underdeveloped, a PECA-style approach to conducting an EC Needs Assessment can trigger positive change through high local stakeholder engagement. Testing this qualitative implementation method with a standardised EC assessment tool in other limited resource contexts is the next step to further improve global EC.

Can Irrigant Agitation Lead to the Formation of a Smear Layer?

IntroductionThis study aimed to assess whether ultrasonic activation (UA) or the EasyClean (EC; BassiEndo, Belo Horizonte, BH, Brazil) or EDDY (ED; VDW, Munich, Germany) systems used to promote agitation of the irrigating solutions during the final irrigation step can lead to smear layer formation in the apical third of the root canal. MethodsThirteen premolars were instrumented with the Reciproc R40 file (VDW) and embedded in silicone, forming a closed irrigation/aspiration system. The teeth were cleaved, and 4 indentations were made on the inner buccal wall of the canal to standardize the observation sites. All the specimens were cleaned in an ultrasonic bath and evaluated under environmental scanning electron microscopy, thus constituting the control group. The same specimens were reassembled, submitted to final irrigation using UA or the ED or EC systems, and classified using a 4-level scoring system. The data were analyzed using the kappa, Pearson, and Kruskal-Wallis tests (P < .05). ResultsSmear layer formation occurred in all of the experimental groups and at all apical levels. At 3 and 4 mm, all of the experimental groups had significantly higher levels of smear layer formation than the control group. At 2 mm, the level of smear layer formation in the UA group was significantly higher than that of the control group, and there were no significant differences among the EC, ED, and control groups. At 1 mm, there were no significant differences between the ED and control groups, and the levels of smear layer formation in the EC and UA groups were significantly higher than that of the control group. There were no significant differences between the ED and EC groups at any of the apical levels. ConclusionsThe smear layer formation occurred in all of the specimens submitted to final irrigation, irrespective of the technique used.

Oxidizing Capacity of Iron Electrocoagulation Systems for Refractory Organic Contaminant Transformation.

Iron electrocoagulation (Fe EC) is normally considered as a separation process. Here, we found that Fe(II)-O2 interactions in Fe EC systems could produce reactive oxidants, mainly hydroxyl radicals (•OH), for refractory organic contaminant transformation. Production of reactive oxidants, probed by benzoate conversion to p-hydroxybenzoic acid (p-HBA), depended on dissolved oxygen (DO) concentration and Fe(II) speciation. Measurable levels of DO were required for significant p-HBA production. Fe precipitates evolved from lepidocrocite to magnetite when DO decreased to below the detection limit. Both experiments and kinetic modeling suggest that the main Fe(II) species contributing to reactive oxidants (mainly •OH) production changed from aqueous Fe(II) initially to lepidocrocite-sorbed Fe(II) with progressive precipitates formation. When DO was not measurable at high currents (≥50 mA or 100 mA/L), reactive oxidant production was ineffective because of pH rise and Fe(II) preservation in magnetite, but it could be enhanced drastically by aeration. The reactive oxidants produced at 30 mA (or 60 mA/L) could degrade about 47% of 10 μM aniline and 34% of sulfanilamide within 6 h of Fe EC treatment. Our findings highlight the importance of reactive oxidants for refractory organic contaminants oxidation in Fe EC systems.

Tests and developments of a long-pulse high-power 170 GHz absorbing matched load

The future EC systems will consist of several gyrotron sources providing MW-level millimeter wave power at a frequency around or above 170 GHz. The development of matched loads is necessary to test the new sources, the components for the transmission lines and the launchers, and must ensure high qualification for compatibility with the nuclear environment. The development at IFP-CNR and LTC of several compact high-power prototypes during the last decade led to a refinement of the overall design, resulting in the present low-reflectivity vacuum-compatible loads. The activity on loads is supported by F4E in view of the development of the EU gyrotron for ITER and required high-power tests at QST (Naka, Japan). Qualification is now supported by new tests at SPC (Lausanne, Switzerland) using the FALCON test-bed designed to test components and the EU gyrotron prototype for the EC system of ITER. These high-power tests, performed on the first CW prototype load (provided with 16 + 16 cooling channels in parallel) and shown in this paper, highlighted the need to improve the mechanical, vacuum and hydraulic design to reach the final goal of 1000s at ∼1 MW.

Treatment of landfill leachate using electrochemically assisted UV/chlorine process: Effect of operating conditions, molecular weight distribution and fluorescence EEM-PARAFAC analysis

Leachate, a highly polluted wastewater, is generated from landfill containing complex compositions which have great impact on the environment. The advanced treatment of biochemically treated landfill leachate using electrochemically assisted UV/chlorine process (UEC) in a flow reactor was investigated. The effects of pH and current density on COD and NH3-N removal by UEC process were evaluated. At the pH value of 5.0, current density of 60mA/cm2, the removal efficiencies for COD and NH3-N were observed as 77% and 87%, respectively. The electrochemical process alone (EC) could obtain relatively high NH3-N removal but very low COD removal, compared with which, the UEC process significantly promoted the removal efficiency of COD while that of NH3-N increased to a very limited extent. Most of NH3-N was converted into N2 and little nitrogen compounds and chloramines were remained in the leachate after 8h treatment. Moreover, the variations of active chlorine and chloride ions were monitored in the EC and UEC systems, and a possible mechanism was proposed for the UEC process. The in situ electro-generated active chlorine and photo-generated radical species should be responsible for the efficient degradation of landfill leachate. The total energy consumption and current efficiency were 216.5 (kWh/kg COD) and 17.5%, respectively, for 8h treatment. In addition, the molecular weight (MW) percentage distribution analysis and PARAFAC analysis of excitation emission matrix (EEM) fluorescence spectroscopy indicated that the organic matters in the leachate were significantly degraded into the fractions with small molecular weight.

Progress in the ITER electron cyclotron heating and current drive system design

An electron cyclotron system is one of the four auxiliary plasma heating systems to be installed on the ITER tokamak. The ITER EC system consists of 24 gyrotrons with associated 12 high voltage power supplies, a set of evacuated transmission lines and two types of launchers. The whole system is designed to inject 20MW of microwave power at 170GHz into the plasma. The primary functions of the system include plasma start-up, central heating and current drive, and magneto-hydrodynamic instabilities control. The design takes present day technology and extends towards high power CW operation, which represents a large step forward as compared to the present state of the art. The ITER EC system will be a stepping stone to future EC systems for DEMO and beyond.The EC system is faced with significant challenges, which not only includes an advanced microwave system for plasma heating and current drive applications but also has to comply with stringent requirements associated with nuclear safety as ITER became the first fusion device licensed as basic nuclear installations as of 9 November 2012.Since conceptual design of the EC system established in 2007, the EC system has progressed to a preliminary design stage in 2012, and is now moving forward towards a final design. The majority of the subsystems have completed the detailed design and now advancing towards the final design completion.

E-commerce retail of extra virgin olive oil: an hedonic analysis of Italian SMEs supply

Purpose– The purpose of this paper is to analyse the relationship between the price of extra virgin olive (EVO) oil and its main quality attributes, in the specific case of business-to-consumers electronic commerce (B2C EC) channel. The final objective is to provide useful insights for small and medium-sized enterprises (SMEs) interested in online selling of EVO.Design/methodology/approach– A hedonic price model was estimated considering the following attributes: packaging, cultivar composition, organic certification, oil extraction method, origin certification and localization of selling firms. A survey was performed in 2012 considering 169 virtual stores of SMEs (farms, mills and bottlers) located in all the main Italian olive-growing areas. A data set of 667 references was used to estimate the implicit prices of considered attributes.Findings– The EVOs sold through virtual stores are highly differentiated on the basis of several quality attributes among which the most important is the certification of origin (protected denominations of origin/protected geographical indication). Therefore the firm location could generate considerable advantages or disadvantages in adopting a B2C EC strategy.Research limitations/implications– Future researches should develop a comparison between the premium prices and costs associated to each attribute in order to find the best product differentiation strategy. An accurate analysis about the implementation and management costs of EC systems as well as an examination of interactions between online and offline sale channels is needed. It would be useful to compare the manufacturer direct sell business model with other business model.Originality/value– Few studies applied the hedonic price model to analyse the retail olive oil market. Nevertheless, no studies have analysed the market of EVO sold in virtual shops.

Enhancement of mineralization of metronidazole by the electro-Fenton process with a Ce/SnO2–Sb coated titanium anode

We compared the degradation behavior of metronidazole (MNZ) under advanced oxidation processes with the aim of enhancing the mineralization of MNZ. Among the advanced processes used, that is, Ce/SnO2–Sb/Ti electrochemical/anode oxidation (EC/AO), the Fenton and the electro-Fenton (EF) processes, the EF process was the most effective. Different input variables, including catalyst concentration, [H2O2]/[Fe2+] molar ratio, and pH level were evaluated to find the optimum condition for mineralization by EF treatment. The total organic carbon was optimally diminished by up to 37% by applying a Fe2+ concentration of 2.0mM, a [H2O2]/[Fe2+] molar ratio of 10:1, and a pH of 2.0. The change in biodegradation was investigated on the basis of the BOD5/CODcr ratio. The ratio of BOD5/CODcr of raw MNZ aqueous (0.227) was increased to 0.252 and 0.345 by the EC and EF systems, respectively. The general toxicity resulting from the different treatments for MNZ aqueous solution was assessed by the Photobacterium bioassay. The toxicity of the EF-treated solution decreased 63%, falling to an effectively non-toxic level, indicating that the EF process can decontaminate and mineralize MNZ into a non-toxic product. According to the BOD5/CODcr ratio, the EF process is a sufficiently powerful pretreatment technology that can increase the biodegradability and decrease the toxicity of wastewater containing MNZ, providing a favorable condition for subsequent biochemical treatment.

Life cycle assessment of cellulose nanowhiskers

Cellulose nanowhiskers refer to elongated, single crystalline, rod-like particles that have at least 1 nm-size dimension. Vegetal fibers are an important source of cellulose for the extraction of nanowhiskers that can be used to reinforce the mechanical properties of different polymers. The present study contributes to the environmental performance of cellulose nanowhiskers production processes at their development stage. Thus, particular environmental aspects and related impacts of two cellulose nanowhiskers product systems are evaluated: nanowhiskers extracted from unripe coconut fibers (EUC system) and from white cotton fibers (EC system). The product systems encompassed fiber, electricity, and chemical production processes. All aspects were measured considering the production of 1 g of nanowhiskers. Life cycle inventory analysis was performed while considering the following environmental aspects: energy, water and emissions present in liquid effluents (chemical oxygen demand (COD), biological oxygen demand (BOD), total nitrogen, nitrate, total phosphorus, phenols, furfural, and hydroxymethylfurfural (HMF)). Life cycle impact was also assessed for climate change, water depletion, eutrophication, and human toxicity impact categories. The comparison between the EUC and EC systems showed that nanowhiskers produced in the EC system required less energy and water, emitted less pollutants, and contributed less to climate change, human toxicity, and eutrophication than those produced in the EUC system. Further research to improve the environmental performance of these systems – before scaling up the results from the laboratory to industry – shall focus on improving yield efficiency, reducing energy and water use during the extraction of nanowhiskers, and recovering substances from effluents possessing market value.

Removal of heavy metals from mining impacted water by an electrocoagulation-ultrafiltration hybrid process

In this study, the use of an electrocoagulation-ultrafiltration (EC-UF) hybrid system for the treatment of mining impacted wastewater was investigated. A model wastewater solution containing copper, lead, cadmium and other constituents representative of mining impacted wastewater was used in this investigation. The effects of key operational parameters including electrolysis time, current density, and solution pH on the performance of the EC and EC-UF systems were systematically investigated. The removal rates of copper and lead by the EC process were consistently higher than that of cadmium. It is probable that the removal mechanism of cadmium was different from that of the base metal copper and lead. Results reported here indicate that an EC-UF hybrid system could be very effective in removing heavy metals at high solution pH. At an acidic condition, the removal efficiency of heavy metal by both EC and UF reduced dramatically. However, the overall removal efficiency by the hybrid EC-UF system remained quite high. Results reported here suggest that EC and UF can complement each other very well for optimum removal efficiency.

Overview of physics research on the TCV tokamak

The Tokamak à Configuration Variable (TCV) tokamak is equipped with high-power (4.5 MW), real-time-controllable EC systems and flexible shaping, and plays an important role in fusion research by broadening the parameter range of reactor relevant regimes, by investigating tokamak physics questions and by developing new control tools. Steady-state discharges are achieved, in which the current is entirely self-generated through the bootstrap mechanism, a fundamental ingredient for ITER steady-state operation. The discharge remains quiescent over several current redistribution times, demonstrating that a self-consistent, ‘bootstrap-aligned’ equilibrium state is possible. Electron internal transport barrier regimes sustained by EC current drive have also been explored. MHD activity is shown to be crucial in scenarios characterized by large and slow oscillations in plasma confinement, which in turn can be modified by small Ohmic current perturbations altering the barrier strength. In studies of the relation between anomalous transport and plasma shape, the observed dependences of the electron thermal diffusivity on triangularity (direct) and collisionality (inverse) are qualitatively reproduced by non-linear gyro-kinetic simulations and shown to be governed by TEM turbulence. Parallel SOL flows are studied for their importance for material migration. Flow profiles are measured using a reciprocating Mach probe by changing from lower to upper single-null diverted equilibria and shifting the plasmas vertically. The dominant, field-direction-dependent Pfirsch–Schlüter component is found to be in good agreement with theoretical predictions. A field-direction-independent component is identified and is consistent with flows generated by transient over-pressure due to ballooning-like interchange turbulence. Initial high-resolution infrared images confirm that ELMs have a filamentary structure, while fast, localized radiation measurements reveal that ELM activity first appears in the X-point region. Real time control techniques are currently being applied to EC multiple independent power supplies and beam launchers, e.g. to control the plasma current in fully non-inductive conditions, and the plasma elongation through current broadening by far-off-axis heating at constant shaping field.

Experience in integrated control of the multi-megawatt electron cyclotron heating system on the TCV tokamak: the first decade

The ECH system on the TCV tokamak consists of six gyrotrons (82.6 GHz/0.5 MW/2 s) used for X2 and electron Bernstein wave (EBW) ECH/ECCD with individual low-field-side launchers. Three additional gyrotrons (118 GHz/0.5 MW/2 s) are used for X3-ECH in a top-launch configuration to provide central heating of high-density plasmas, at nearly 3 times the cutoff density of X2. The X2 subsystem was installed by the end of 1999 and the X3 subsystem by the end of 2003, making 4.2 MW available for experiments. The installation work provides data related to testing, repair and reliability of a complex ECH system designed to allow the highest possible degree of automation, integration and flexibility in the experimental programme. Its effective integration into the TCV plant is evidenced by the fact that the mean time between shots when operating with ECH increases roughly in proportion to the increase in the resources required to prepare, monitor and record the experimental sessions. Each of the X2 and X3 subsystems is routinely individually operated by one person. This gives confidence that with proper layout, planning and integration, the EC systems of future fusion experiments, such as ITER, can routinely provide reliable actuators, on demand.

EC and WTO Subsidy Control Systems – some Reflections

EC and WTO Subsidy Control Systems – some Reflections