Effects of temperature on melt electrospinning with auxiliary heating: experiment and simulation study

In this study, the effect of the heating temperature of the spinneret on the melt electrospinning process under the condition of application of auxiliary heating was investigated, in a systematical and comprehensive way. The temperature distribution of the melt jet during the melt electrospinning process was simulated by finite element software in order to provide a good deal of insight into the experimental results. In addition, high-speed photography was adopted to capture images of jet formation and jet motion during the melt electrospinning process. The experimental results indicated that the cooling rate of the polypropylene jet decreases obviously under the condition of auxiliary heating; in addition, the higher spinneret temperature leads to greater drafting force, a drawing fiber drafting rate, and greater jet whipping motion, which is conducive to secondary drawing and refinement of the jet.

Enhanced confinement in diverted negative-triangularity L-mode plasmas in TCV

The favourable confinement properties of negative-triangularity (NT) tokamak configurations were discovered in the TCV tokamak in the late 1990’s and were documented over the two following decades, through investigations of predominantly electron-heated plasmas in limited topologies. The most recent experimental campaign in TCV has marked a leap forward, characterized by the development of a variety of diverted NT shapes that are robustly stable with basic Ohmic heating. The application of auxiliary heating, directed now at both electrons and ions (using electron-cyclotron resonance heating as well as neutral-beam injection), has enabled the achievement of record performances for L-mode plasmas, with normalized β values reaching 2.8 transiently (as well as 2 in steady state, but reverting to a limited configuration) and with comparable ion and electron temperatures. The systematic confinement enhancement with NT is confirmed in these experiments. The L-mode existence space is broader than at positive triangularity, with only sporadic transitions to Hmode observed up to 1.4-MW heating power regardless of the magnetic-field-gradient direction relative to the X-point. These experiments are planned to be continued with even higher power following a heating-source upgrade.

A novel measurement of marginal Alfvén Eigenmode stability during high power auxiliary heating in JET

The interaction of Alfvén Eigenmodes (AEs) and energetic particles is one of many important factors determining the success of future tokamaks. In JET, eight in-vessel antennas were installed to actively probe stable AEs with frequencies ranging 25-250 kHz and toroidal mode numbers |n| < 20. During the 2019-2020 deuterium campaign, almost 7500 resonances and their frequencies f, net damping rates γ < 0, and toroidal mode numbers were measured in almost 800 plasma discharges. From a statistical analysis of this database, continuum and radiative damping are inferred to increase with edge safety factor, edge magnetic shear, and when including non-ideal effects. Both stable AE observations and their associated damping rates are found to decrease with |n|. Active antenna excitation is also found to be ineffective in H-mode as opposed to L-mode; this is likely due to the increased edge density gradient's effect on accessibility and ELM-related noise's impact on mode identification. A novel measurement is reported of a marginally stable, edge-localized Ellipticity-induced AE probed by the antennas during high-power auxiliary heating (ICRH and NBI) up to 25 MW. NOVA-K kinetic-MHD simulations show good agreement with experimental measurements of f, γ, and n, indicating the dominance of continuum and electron Landau damping in this case. Similar experimental and computational studies are planned for the recent hydrogen and ongoing tritium campaigns, in preparation for the upcoming DT campaign.

Combining Dual Fluidized Bed and High-Temperature Gas-Cooled Reactor for Co-Producing Hydrogen and Synthetic Natural Gas by Biomass Gasification

Biomass gasification to produce burnable gas now attracts an increasing interest for production flexibility in the renewable energy system. However, the biomass gasification technology using dual fluidized bed which is most suitable for burnable gas production still encounters problems of low production efficiency and high production cost. Here, we proposed a large-scale biomass gasification system to combine dual fluidized bed and high-temperature gas-cooled reactor (HTR) for co-production of hydrogen and synthetic natural gas (SNG). The design of high-temperature gas-cooled reactor biomass gasification (HTR-BiGas) consists of one steam supply module to heat inlet steam of the gasifier by HTR and ten biomass gasification modules to co-produce 2000 MWth hydrogen and SNG by gasifying the unpretreated biomass. Software for calculating the mass and energy balances of biomass gasification was developed and validated by the experiment results on the Gothenburg biomass gasification plant. The preliminary economic evaluation showed that HTR-BiGas and the other two designs, electric auxiliary heating and increasing recirculated product gas, are economically comparative with present mainstream production techniques and the imported natural gas in China. HTR-BiGas is the best, with production costs of hydrogen and SNG around 1.6 $/kg and 0.43 $/Nm3, respectively. These designs mainly benefit from proper production efficiencies with low fuel-related costs. Compared with HTR-BiGas, electric auxiliary heating is hurt by the higher electric charge and the shortcoming of increasing recirculated product gas is its lower total production. Future works to improve the efficiency and economy of HTR-BiGas and to construct related facilities are introduced.

A fast tool for ICRH + NBI modelling within the EU-IM framework

Most if not all tokamak heating scenarios involve multiple ion populations being heated simultaneously. To allow the simulation of various aspects of physics dynamics determining the characteristics of operational scenarios in a flexible way, speedy yet sufficiently accurate models are needed, and they should be connected to each other via a ‘backbone’. Under the umbrella of EUROfusion's Integrated Modelling efforts, such a structure is provided. The present paper focuses on one physics aspect: auxiliary heating. After solving the wave equation or beam source equation, this requires solving a set of coupled Fokker–Planck equations for the various populations involved. The adopted modules – enabling accounting for the Coulomb collisional interaction of several non-Maxwellian (minority, majority and beam) populations – are discussed and a practical example of their use is provided: the JET ‘baseline’ scenario heating a minority of ${}^3\textrm {He}$ ions in a balanced D $+$ T mix heated by D and T neutral beams.

Physics-Based Digital Twin Identifies Trade-Offs Between Drying Time, Fruit Quality, and Energy Use for Solar Drying

Solar drying is regarded as a less reliable process compared to continuous hot-air drying due to the intermittency of solar radiation. This problem is mitigated by equipping solar dryers with thermal storage, dehumidifier units, or auxiliary heating that enhances drying continuity during night time. In this study, we combine a mechanistic fruit drying model, quality models (vitamin C decay and browning reaction) and weather data to evaluate the drying characteristics and quality evolution of apple fruit with and without the aforementioned improvement strategies. By coupling to measured weather conditions, a digital twin of the drying fruit is established. The twin outputs drying times and final product quality for a specific fruit type and size, a particular dryer configuration, and specific weather conditions. The trade-offs between drying time, final product quality and energy use for the different improvement strategies of solar drying are documented. We found that solar drying may benefit from the slower drying due to the improvement of product quality. Compared to the other improvement strategies, dehumidification of the drying air is shown to be superior in retaining the vitamin C content and prohibiting the browning reaction. However, in general, drying with auxiliary heating is found to balance the trade-offs between drying time, final product quality and energy use since the weather-dependency of the process is mitigated. Additionally, we quantified the impact of a pre-treatment process that modifies the permeability of the fruit tissue by breaking the cell membrane. We found that inducing such lysis is more effective in decreasing the drying time when drying is conducted at low (room) temperature. This study shows that using the developed digital twin, future drying process and control strategies could be optimized in real-time for every single drying run.

РАЗРАБОТКА КЕРАМИЧЕСКИХ ТЕПЛОГЕНЕРИРУЮЩИХ СОЛНЕЧНЫХ КОЛЛЕКТОРОВ-ПЛИТ

An urgent problem of the modern world is the global warming of the Earth, fraught with a climatic catastrophe. In addition, an important strategic task for Armenia is the issue of reducing the costly imported risky supplies of hydrocarbon and nuclear fuel and increasing the country's energy security. The Union of Armenian Ceramics Manufacturers has developed a new generation of ceramic heat-generating solar collector- plates, which allow converting solar energy into thermal energy of hot water in a more efficient, easily accessible and cheap way. Water heated in such an environmentally friendly and widely available way can be used for hot water supply (DHW) and additional auxiliary heating of premises. In Armenia, to obtain hot water for domestic and technical needs, electricity is used and hydrocarbon fuel is burned in an amount equivalent to USD 200...300 million per year. At the same time, tens of thousands of tons of carbon dioxide, water vapor and other greenhouse gases are emitted into the atmosphere. With the massive introduction of ceramic solar collector plates, for example, in the form of roof tiles or other facade elements, it is possible to obtain very cheap hot water for hot water supply and warm air for additional auxiliary heating of premises in the spring - autumn seasons of the year. The mass introduction of collector tiles (the so-called "heliofication" of buildings, countries) will save a significant amount of electricity, natural gas and other types of fuel for heating water, and significantly reduce the emission of greenhouse gases into the atmosphere. The large-scale introduction of solar roof tiles in several countries in the region is likely to help mitigate the global warming. The solarization of Armenia will also make it possible to reduce the expenditure of financial resources for the purchase of energy carriers and direct the saved funds to the development of the country's economy.

Preparations for a European R&D roadmap for an inertial fusion demo reactor

A European consortium of 15 laboratories across nine nations have worked together under the EUROFusion Enabling Research grants for the past decade with three principle objectives. These are: (a) investigating obstacles to ignition on megaJoule-class laser facilities; (b) investigating novel alternative approaches to ignition, including basic studies for fast ignition (both electron and ion-driven), auxiliary heating, shock ignition, etc.; and (c) developing technologies that will be required in the future for a fusion reactor. A brief overview of these activities, presented here, along with new calculations relates the concept of auxiliary heating of inertial fusion targets, and provides possible future directions of research and development for the updated European Roadmap that is due at the end of 2020. This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 2)’.