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Numerical Analyses on Liquid-Metal Magnetohydrodynamic Flow in 180°-Turn Channel
Hiroshige Kumamaru,
Naohisa Takagaki
Issue:
Volume 7, Issue 1, February 2019
Pages:
1-7
Received:
15 January 2019
Accepted:
19 February 2019
Published:
1 March 2019
Abstract: Numerical calculations have been performed on liquid-metal magnetohydrodynamic (MHD) flow in a 180°-turn (i.e. hairpin-shaped) channel, in order to contribute to design of a fusion reactor blanket. A magnetic field is applied in a direction perpendicular to an inlet channel, a turning channel (turning section) and an outlet channel. The continuity equation, the momentum equation and the induction equation have been solved numerically. In this study, attention is focused on pressure drops along the channels and pressure distribution in the turning channel. The Hartmann number (indicating magnetic field strength), the Reynolds number and the channel aspect ratio, in the present calculations, cover 100 to 500, 1000 to 5000 and 1 to 1/4, respectively. The following things have become clear from calculation results. The total MHD pressure drop from a channel inlet to a channel outlet agrees approximately with that for the total channel length, meaning that the loss coefficient for the turning channel is nearly zero or small. For large Reynolds numbers, the pressure in the peripheral region of the turning channel becomes larger than that at the channel inlet, due to the centrifugal force acting in the turning channel. It is considered that this pressure increase should be taken into account in designing a fusion reactor blanket.
Abstract: Numerical calculations have been performed on liquid-metal magnetohydrodynamic (MHD) flow in a 180°-turn (i.e. hairpin-shaped) channel, in order to contribute to design of a fusion reactor blanket. A magnetic field is applied in a direction perpendicular to an inlet channel, a turning channel (turning section) and an outlet channel. The continuity ...
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Numerical Estimation of Heat Recovery within a Distributed Incinerator Using Water and Hydrocarbons as Working Fluids
Hikaru Yamashiro,
Tomoyasu Yara,
Kenji Fukutomi
Issue:
Volume 7, Issue 1, February 2019
Pages:
8-16
Received:
7 January 2019
Accepted:
13 March 2019
Published:
3 April 2019
Abstract: The potential of a cogeneration system combined with a small combustion furnace was investigated in this study. The heat transfer between the exhaust gas and working fluid flowing in a spiral tube heat exchanger was estimated numerically and the amount of vapor generated was predicted. The combustion chamber had a 0.49 m3 inside volume with a chimney height of 2.5 m and an inner diameter of 0.28 m. A uniform gas side temperature condition that was referenced from the results of a preliminary experiment and a computational fluid dynamics simulation were adopted to simplify calculations and clarify the effects of working fluids. The amounts of heat recovery when utilizing water and other types of working fluids (Pentane, Butane) were compared. The most effective tube length considering pressure drop and phase change was also predicted. Isentropic theoretical thermal efficiency and T-s diagrams are analyzed to evaluate the vapor-power conversion rate using waste heat. As a result, a potential the heat recovery rate of approximately 100 kW at a 150 kg/h mass flow rate is expected.
Abstract: The potential of a cogeneration system combined with a small combustion furnace was investigated in this study. The heat transfer between the exhaust gas and working fluid flowing in a spiral tube heat exchanger was estimated numerically and the amount of vapor generated was predicted. The combustion chamber had a 0.49 m3 inside volume with a chimn...
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Magnetically Levitated Linear Drive with Repulsive Magnetic Guidance
Markus Raab,
Bernd Gundelsweiler,
Wolfgang Schinköthe
Issue:
Volume 7, Issue 1, February 2019
Pages:
17-25
Received:
15 February 2019
Accepted:
28 March 2019
Published:
18 April 2019
Abstract: Linear direct drives are often used when high performance is required, because of their high dynamic and their good position accuracy. Usually direct drives are used with linear rolling guidance. In clean room and vacuum applications linear rolling guidance cannot be used as particles can be cause problems. In this paper a magnetically levitated linear direct drive with a combination of repulsive permanent magnet stabilization and Lorentz force based stabilization is presented. With the joint use of magnet fields high dynamic can be achieved in combination with a cost efficient hardware. Due to the use of repulsive permanent magnet forces, it is possible to levitate an armature with nearly no power dissipation. An ad-hoc control reduces the power dissipation to a value less than 10 mW.
Abstract: Linear direct drives are often used when high performance is required, because of their high dynamic and their good position accuracy. Usually direct drives are used with linear rolling guidance. In clean room and vacuum applications linear rolling guidance cannot be used as particles can be cause problems. In this paper a magnetically levitated li...
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Modelling of the Nnormobaric and Hyperbaric Facilities Ventilation
Issue:
Volume 7, Issue 1, February 2019
Pages:
26-33
Received:
18 March 2019
Accepted:
5 May 2019
Published:
26 May 2019
Abstract: This paper is the result of many work and research programs. During the execution of the projects, it was proposed a new mathematical model of the process of ventilation of a semi-closed rebreather. Its validation required making a special simulator of gas exchange in the breathing process. Use of the device made experimental validation of the proposed model possible. This model has been adjusted to the process of ventilation in hyperbaric chambers. The validation process required developing a new type of carbon dioxide emission simulator. The generalization of the adopted method for the submarine ventilation process was only an obvious consequence of earlier considerations. However, the validation process required to undertake extensive research on a real object, which confirmed the validity of the modelling method adopted. The research on ventilation of the mining excavation constituted the validation of the adopted research approach. In typical residential and public buildings, similar methods have been used relatively recently. In general, they involve air-conditioning of the sealed buildings. This entails the need to regenerate the respiratory atmosphere inside, making them similar to military facilities. Methods of protection against contamination can be used with regard to atmospheric pollution, especially in the work environment. As in the case of military facilities, the methods of modelling ventilation in standard and hyperbaric objects described here would allow developing more accurate methods to design and use ventilation and air-conditioning systems in buildings.
Abstract: This paper is the result of many work and research programs. During the execution of the projects, it was proposed a new mathematical model of the process of ventilation of a semi-closed rebreather. Its validation required making a special simulator of gas exchange in the breathing process. Use of the device made experimental validation of the prop...
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