1,721,134 research outputs found
Experimental study of the propellant gas load required for pellet injection with ITER-relevant operating parameters
No full textAn existing pipe gun test facility at ORNL was used for an experimental study of propellant gas loads required for ITER-relevant pellet injection, with the key objective of determining the minimal amount of gas required for optimal pellet speeds. Two pellet sizes were tested, with nominal 4.4 and 3.2 mm diameters comparable to pellets planned for fueling and ELM pacing in ITER, respectively. A novel scheme was used to freeze solid pellets from room temperature gas; this facilitated operations at higher temperatures (14.5 to 16.5 K, similar to those planned for extruder operations for ITER pellet injectors) and thus lower pellet breakaway pressures and gas loads. Most of the single-shot D2 pellet tests were carried out with a relatively low H2 propellant gas load of ∼0.0133 bar-L. Some limited testing was also carried out with a mixed propellant gas that consisted mostly of D2, which is more representative of the gas that will be used for ITER pellet injection. In testing it was found that this reference gas load resulted in pellet speeds in close proximity to a speed limit (∼300 m/s) previously determined in a series of tests with D2 pellets shot through a mock-up of the curved guide tubes planned for the ITER installation (for pellet fueling from the magnetic high-field side). The equipment, operations, and test results are presented and discussed, with emphasis on the relevance for ITER operations
Selectable flight tube design developments for ITER fueling, ELM pacing, and impurity pellets
No full textITER fueling and Edge Localized Mode (ELM) pacing pellets will be created by punching and chambering pellets with a solenoid operated cutter from an extrudate formed by a twin-screw extruder. The cut pellets are then accelerated down a flight tube by a fast pneumatic valve. The impurity pellets are formed in-situ with a pipe gun technique and accelerated down a flight tube with the same pneumatic valve design. © 2015 IEEE
Novel Non-Evaporable Getter Materials and Their Possible Use in Fusion Application for Tritium Recovery
Full text linkNon-evaporable getters (NEGs) are metallic compounds of the IV group, particularly titanium and/or zirconium-based alloys and are usually used as pumps in vacuum technologies since they are able to sorb, by chemical reactions, most of the active gas molecules, with particular efficacy towards hydrogen isotopes. This work suggests an alternative application of these materials to fusion nuclear reactors, where there is the need to recover small amount of tritium from the large helium flow rate composing the primary coolant loop. Starting from the tritium mass balance inside the primary coolant loop, the amount of coolant to be routed inside the coolant purification system (CPS) is identified. Then a feasibility study, based on the bulk getter theory, is presented by considering three different commercial alloys, named ST707, ST101 and ZAO. The results provide the mass, the area and the regeneration parameters of the three different alloys necessary to fulfill the requirements of the CPS unit. By comparing the features of the three alloys, the ZAO material appears the most promising for the proposed application because it requires the lower amount of material and a lower number of regeneration cycles
Perspectives for the high field approach in fusion research and advances within the Ignitor Program
No full textThe Ignitor Program maintains the objective of approaching D-T ignition conditions by incorporating systematical advances made with relevant high field magnet technology and with experiments on high density well confined plasmas in the present machine design. An additional objective is that of charting the development of the high field line of experiments that goes from the Alcator machine to the ignitor device. The rationale for this class of experiments, aimed at producing poloidal fields with the highest possible values (compatible with proven safety factors of known plasma instabilities) is given. On the basis of the favourable properties of high density plasmas produced systematically by this line of machines, the envisioned future for the line, based on novel high field superconducting magnets, includes the possibility of investigating more advanced fusion burn conditions than those of the D-T plasmas for which Ignitor is designed. Considering that a detailed machine design has been carried out (Coppi et al 2013 Nucl. Fusion 53 104013), the advances made in different areas of the physics and technology that are relevant to the Ignitor project are reported. These are included within the following sections of the present paper: main components issues, assembly and welding procedures; robotics criteria; non-linear feedback control; simulations with three-dimensional structures and disruption studies; ICRH and dedicated diagnostics systems; anomalous transport processes including self-organization for fusion burning regimes and the zero-dimensional model; tridimensional structures of the thermonuclear instability and control provisions; superconducting components of the present machine; envisioned experiments with high field superconducting magnets. © 2015 IAEA
High Temperature Humidity Sensor Calibration
No full textThe request of calibration of humidity sensors at high temperature and high relative humidity is quite common in many industrial sectors (food, pharmaceutical, etc.) and in environmental monitoring applications. However, in spite of a widespread traceability need in such measurement conditions, only few calibrations or industrial laboratories are available to meet this demand. This is probably due to the high costs associated with the calibration facilities and to the technical difficulties for realisation, use and maintenance of such a laboratory for humidity sensor calibration at high temperature.
In the work the authors highlight the main issues connected with the realisation and characterisation of such calibration systems. Experimental investigations on the behaviour of the calibration reference standards and the traditional working instruments in the high temperature and high humidity regimes are reported. Specific calibration problems associated with the humidity sensor response curves and their dependence from the temperature are discussed. Finally, the calibration uncertainty of humidity sensors in the above-mentioned conditions is estimated
Proposal of a new method for the characterization and operational air leakages assessment in HVAC systems
Full text linkReducing air leakages in HVAC systems is potentially one of the actions with the best potential for energy savings in the residential sector. The assessing of air leakages in HVAC systems is currently addressed in two ways: i) the traditional DALT (Ducts Air Leakage Tests) to characterize and compare ductwork and ii) the ASHRAE 215:2018 standard method to measure leakage at nominal working conditions. In this paper an innovative experimental method for assessing air leakages in HVAC systems at operative conditions is proposed. The method is based on flow rate measurements at different pressures and performed with closed terminal dampers. The so called “Shut-Off Method” has been then experimentally validated in a real plant showing good agreement with the ASHRAE 215 procedure. Finally, on the basis of the Shut-Off model application, the leakage coefficient used by the standard DALT classification procedure was calculated, showing leakage performance 2,3 times worse than the Eurovent Class A requirements
INFLUENZA SUGLI INDICI DI VALUTAZIONE DEI REQUISITI ACUSTICI PASSIVI IN SITU DELLA MISURA DEL TEMPO DI RIVERBERAZIONE
No full textA diversi anni dall’entrata in vigore del DPCM 5\12\97 si verificano sempre più casi di contenzioso fra venditore ed acquirente, talvolta basate su risultati differenti ottenuti in situ, nelle misure fatte eseguire dalle parti in causa. Il presente lavoro valuta come la misura del tempo di riverberazione in opera, eseguita in uno stesso ambiente, con l’utilizzo delle metodologie di misura basate sul rumore interrotto o sul rumore impulsivo, incida sugli indici di valutazione dei requisiti acustici passivi a seconda della tipologia di sorgenti utilizzate
Experimental evaluation of thermal mass smart meters influence factors
No full textNew static thermal mass principle is a very promising technology for gas flow-metering since it offers very significant potential such as digital output, absence of moving parts, direct mass measurement. Unfortunately, gas quality is expected to affect metrological performance of thermal mass flow-meters (TMFs), as far as flow disturbances and such conditions often occur in modern networks. In this paper the authors investigate the sensitivity of TMFs with natural gas quality changes and different flow disturbances. To this end, a metrological test campaign has been carried out through specifically designed laboratory test bench and facilities. The results of the tests with gas quality changes show the capillary TMFs are able to recognize the natural gas flowing strictly included in the EN 437 group H and to consequently apply specific correction factors. On the other hand, capillary TMFs have been found sensitive to high contents of CO2 and N2, like in biogas and natural gases at the borders of group H. Finally, flow disturbances tests show the accuracy of full bore insertion in line TMFs is affected by the interaction between sensor and piping both for double out-of plane bend and single 90° bend disturbances
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