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[en] The article considers experimental studies of the hydrodynamic characteristics of the active section of the self-draining solar loop of a heating system. This element is designed as a flow constrictor referred to as Ventury tube, with a high degree of flow constriction of 2–5 in the region with strong viscous resistance. The experimental data are processed in a criteria form, the general type of which is obtained by dimensional technique and compared with data from other authors. The obtained criteria dependences can be used to calculate the hydrodynamic characteristics of the active section of the self-draining solar loop of a heating system.
[en] In this paper, experimental investigation of the molten metal jet's colliding and spreading behaviors on the flat steel surface covered with water layer was carried out. High-frequency induction heating system was utilized to produce the molten metal sample and it was released to the wet surface from a fixed elevation. As the molten metal collides against the surface, it rapidly goes through solidification while spreading on the wet surface. High-speed thermo-camera was utilized to measure the molten metal's surface temperature during the spreading transient. Once the molten metal completely solidifies, molten metal's spread area and thickness were measured. From the obtained database, a dimensional analysis was conducted to investigate the key parameters responsible for the molten metal spreading on the wet surface. Based on the key non-dimensional parameters identified in the current analysis, the new empirical correlation was proposed. Its predictive capability was found to be 18.9% in mean absolute relative deviation.
[en] The temperature control system of calcination furnace KR-260E has been design for calcination process UO2 kernel. The design of the temperature control system is to replace the old damaged control module. The temperature controller of control module used is adjusted to kernel UO2 calcination process with a gradual heating system. The controller is capable of storing 30 heating program patterns and each program can contain up to 10 steps of operation. The functional system test of the calcination furnace KR-260E temperature control system is carried out under no load conditions and is carried out gradually with consideration of the new heating conditions. The functional testing stage is at 200 °C, 300 °C, 450 °C and 600 °C with a 250 °C/hour heating ramp setting, 1 hour temperature soaking and the ramp decreasing to 250 °C/hour. The deviation at 200 °C deviation is 2,7 °C was obtained, at 300 °C the temperature deviation is 1,3 °C, at 450 °C was obtained overshoot is 9,8 °C and the mean temperature deviation is 0.2337 °C, and at 600 °C obtained an overshoot is 10,3 °C and an average temperature deviation is 5.0453 °C. The result of this function test indicates that the furnace can function for kernel UO2 calcination operation. (author)
[en] Highlights: • Test of three ESPs at old residential wood combustion systems over two heating seasons. • Collection of a huge set of plant operation data during a continuous 2 year monitoring. • Comprehensive evaluation of the plant monitoring data to analyse the ESP operation. • Data from two dedicated emission measurement campaigns per heating season and ESP. • Comprehensive data on ESP operation, availability and emission reduction efficiency. - Abstract: To assess the applicability of electrostatic precipitators (ESP) for particulate matter (PM) emission reduction in old residential wood heating appliances comprehensive field tests with accompanying ESP operation monitoring and dedicated emission measurement campaigns have been performed in the region of Graz (AT). Three OekoTube ESPs were thereby tested during the heating seasons 2014/2015 and 2015/2016 at different sites with rather old respectively high-PM-emission wood burning devices. Before installing the ESPs at the field testing sites they were checked in the lab regarding functionality and precipitation efficiency. The evaluation of the plant monitoring data collected during the field tests revealed high seasonal ESP availabilities between 80.2% and 97.7%. Dedicated test runs with emission measurements at the different testing sites showed high precipitation efficiencies which were well comparable with those gained during preceding lab-tests. Based on these results it can be concluded, that ESP models like the OekoTube are suitable as retrofit units in old appliances and have due to their high availability and particle precipitation efficiency the potential to contribute to a significant reduction of particulate matter emissions from old residential wood burning systems.
[en] Full text: In order to achieve thermonuclear-relevant plasma parameters in ITER, the auxiliary heating systems have to provide 50 MW, out of which 33 MW by two neutral beam injectors (NBI), each designed to operate at 1 MV, 40 A for one hour. The unprecedented parameters and the complexity of the NBI systems have led to recognize the need of a dedicated test facility to carry out an international R&D programme aimed at realizing, testing and optimizing the prototype of the NBI and to assist ITER during its operation. This facility is under construction in Padova Italy at Consorzio RFX premises and hosts two experiments: MITICA, a 1 MeV full-size prototype of the ITER NBI, and SPIDER, a full-size prototype of the ion source for ITER NBI. The realization of the two experiments is carried out with the main contribution of the European Union, channelled through the Joint Undertaking for ITER (F4E), the ITER Organization and Consorzio RFX, with the Japanese and the Indian ITER Domestic Agencies (JADA and INDA) and European laboratories, such as IPP-Garching among others. The realization of MITICA and SPIDER progresses in parallel; presently, the installation phase of SPIDER is proceeding in good agreement with the general plan. This paper mainly focusses on the integration issues and complementary research toward the SPIDER first operation, expected for next year. This is a very crucial phase, evolving along three main parallel paths: integration and testing of SPIDER components, completion and implementation of diagnostics and preparation of operation and research plan. The most interesting aspects of the wide set of activities, studies and further developments, all concurrent to determine the success of the SPIDER start of operation and exploitation will be described and discussed. (author)
[en] The Prototype-Material Plasma Exposure eXperiment (Proto-MPEX) linear plasma device is a test bed for exploring and developing plasma source concepts to be employed in the future steady-state linear device Material Plasma Exposure eXperiment (MPEX) that will study plasma-material interactions for the nuclear fusion program. The concept foresees using a helicon plasma source supplemented with electron and ion heating systems to reach necessary plasma conditions. Here in this paper, we discuss ion temperature measurements obtained from Doppler broadening of spectral lines from argon ion test particles. Plasmas produced with helicon heating alone have average ion temperatures downstream of the Helicon antenna in the range of 3 ± 1 eV; ion temperature increases to 10 ± 3 eV are observed with the addition of ion cyclotron heating (ICH). The temperatures are higher at the edge than the center of the plasma either with or without ICH. This type of profile is observed with electrons as well. Finally, a one-dimensional RF antenna model is used to show where heating of the plasma is expected.
[en] The propagation characteristics and physical nature of low-frequency waves observed in the ionosphere during heating of the near-Earth plasma by a powerful short-wavelength radiation are investigated using the singular value decomposition method. The experimental results obtained with the Sura midlatitude heating facility and detected by the onboard equipment of the DEMETER satellite were used. The ion composition of the near-Earth plasma is estimated from the spectral characteristics of the observed radio waves. The method is verified using results of full-scale measurements performed at altitudes corresponding to the Earth’s outer ionosphere.
[en] A new generation isothermal multichannel microcalorimetry system based on an earlier reported system which has been commercialised under the name “Thermal Activity Monitor” (TAM) is described and evaluated. The system has a modular design constituting a thermostat that accommodates up to four calorimetric units. The temperature stability of the thermostat has been improved 100-fold compared to the original TAM mainly due to novel technology for absolute temperature measurements consisting of a platinum resistance sensor combined with a high-resolution thermoelectric (TE) module housed in an aluminium body for temperature fluctuation measurements. In combination with the continuous liquid overflow design similar to that of the original TAM with an inbuilt Peltier cooling/heating system forming part of a single feedback regulation system, temperature drifts/fluctuations over 24 h better than ±10 µK have been achieved. Besides the isothermal mode, the thermostat can be controlled to perform temperature ramps with rates from close to 0 up to 2 K h−1. Two basic designs of twin heat flow calorimeters are described. One is similar to those originally reported having the sample and reference sides mirrored horizontally, and with a solid heat sink time constant of 6000 s. The other has the sample and reference mirrored on the vertical axis with a solid heat sink time constant of 500 s making it considerably smaller. Both calorimeters are equipped with insertion ampoule holders that can hold 4 mL reaction volume. The lowest observed long-term signal stability among a population of data from the two calorimeters was ±17 nW/24 h for the calorimeter with the larger heat sink and ±50 nW/24 h for the calorimeter with the smaller heat sink. Test experiments indicated the absence of significant systematic errors for the former calorimeter type while a maximum of 2–3% error was observed for the latter type. This difference between the two calorimeter types was attributed to different positioning of the TE sensors relative to the calibration heater.
[en] In this paper, a simple yet accurate model is proposed for real-time control and optimization of two-phase flow plate heat exchanger (PHE). The model is derived with selected controllable or measurable I/O parameters and heat mass transfer equations by mechanism analysis. The linear and nonlinear least-squares methods are adopted to identify unknown or empirical parameters to reduce the error of evaluation and prediction in applications. The modeling approach takes advantages of both mechanism and empirical model, which has the effectiveness that the unreachable parameters are eliminated while the computation is reduced with wide operating range. Validation was carried out in a substation in a district heating system, and the testing results showed that the proposed model can predict the performance of the PHE with a maximum error less than ±8% that satisfied the requirements of real-time control and optimization in applications.
[en] Full text: The paper summarizes the studies carried out on the use of an ion cyclotron range of frequency system on DEMO in the framework of the PPPT. An ion cyclotron range of frequency (ICRF) heating system can contribute significantly to various plasma phases during an experimental cycle (“shot”). It can be used in the plasma start-up and current ramp-up phase, where election heating is beneficial. After this phase, various heating schemes that aim at direct or indirect bulk ion heating offer different paths to suitable operation points with a large power gain factor and large efficiencies. Although mainly meant to heat the plasma, ICRF power can also contribute to current drive and plasma rotation and can help to control MHD instabilities. ICRF power can further be used to ensure a “soft” termination of the discharge. It was confirmed experimentally that the ICRF can be used for all those functions. With the present emphasis on a pulsed DEMO machine (the EU DEMO1 2015 baseline) we studied in more detail the heating scenarios and a corresponding antenna. In DEMO, to reduce as much as possible the number and area of openings in the vessel, heating systems with high power density, using the smallest port area, would be expected to be favoured. An alternative is to integrate the heating system into the machine. ICRF antennas have been operating in machines like JET and ASDEX-Upgrade close to the plasma without using a large port for several tens of years without any problems. In DEMO, a distributed antenna, integrated in the blanket, covering the full 360° toroidal extend and of the travelling wave type would have a low power density, not use any port (except for the feeds) and be compatible with the tritium breeding. This new antenna type allows for an improved coupling by being able to work with low k ‖ and conceptually avoids, with its 360° symmetry, the occurrence of sheaths and thus additional impurity production. Such an integrated antenna needs to fulfil a number of conditions on compatibility with blanket function and remote handling, on modularity, level of safety and complexity. Scoping studies indicate that there are indeed no show-stoppers. A test of this type of antenna in a tokamak plasma is needed. It could be done in several steps, but a final proof of principle on a large machine will be essential. (author)