The experimental facility for investigation of MHD heat transfer in perspective coolants in nuclear energetics (original) (raw)
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Magnetohydrodynamics, 2016
Liquid metal flows under a high thermal load and strong magnetic field are of great interest in the context of the development of fusion reactor cooling systems. In this study, a downward flow of mercury in a heated duct, affected by a coplanar magnetic field (directed transverse to the main flow and along the long side of the duct), is studied experimentally for symmetrical (two-sided) and asymmetrical (onesided) duct heating, showing different flow behaviors in the magnetic field. We show that in spite of the qualitatively different structure of the downward flow in the duct with different heating modes, the applied coplanar magnetic field provides a rather general reaction, which includes two scenarios determined by the Richardson number. At high Richardson numbers (Ri J 1), the Nusselt number tends toward the turbulent limit, as expected in the channel without a magnetic field, and at low Richardson numbers (Ri K 1), the Nusselt number tends to its laminar limit.
Temperature fluctuations accompanying MHD heat transfer of liquid metal downflow in a pipe
Fluid Dynamics Research, 2018
Liquid metals are prospective coolant and working media for fission and fusion applications. In latter case they will be affected by very high magnetic fields. By now there is no possibility to recreate these conditions directly, and research is being made using numerical simulations and model liquids. Special care is taken to the possible thermogravitational phenomena in the presence of magnetic field. Temperature and temperature fluctuations are used to describe the flow structure as they can be obtained from experiments with high accuracy and localization. Area of intense fluctuations existence was explored using several experimental facilities including a new HELME Facility with magnetic fields of up to 2.7 Tesla. Area where fluctuations occur and specific of transition regions have been explored for the round vertical pipes with down flow and uniform heating (Grashof number of up to 1.2•10⁸) as a basic configuration with explicit boundary conditions.
Measurement of the Heat Transfer Coefficient for Mercury Flowing in a Narrow Channel
Journal of Heat Transfer-transactions of The Asme, 2002
A heat exchanger concept is developed that extracts energy from liquid lithium reactor coolant to evaporate potassium used in a Rankine power cycle. The heat exchanger is based on flow channels with hydraulic diameters of order 100 microns, which evokes some physical flow characteristics not common to heat exchangers with conventional dimensions. Liquid metal superheat prior to incipience of boiling is explored and the potential for bulk liquid flow temperatures in excess of saturation is explained. Design methods to stabilize evaporator flow and to completely avoid liquid entrainment in the evaporator by limiting vapor velocity and liquid film Reynolds number are also developed.
Energies, 2022
The necessity of coolant flow consumption measurement accuracy increase in the nuclear reactor primary circuit has been substantiated. Additionally, the need to control the coolant condition in the current flow inside the pipeline is shown. Nowadays, the real-time coolant’s condition control function is not implemented at stationary nuclear power plants or mobile nuclear power plants used in moving objects. It is shown that a coolant consumption measurement error decreases and its condition data availability increases the heat transfer efficiency and the electrical energy generation (without the nuclear reactor and steam generator design change). Problems arising during coolant consumption control using various flowmeters models in the nuclear reactor primary circuit are considered. It has been found that nuclear magnetic flowmeters can solve these problems. New difficulties are noted as emerging when using pulsed nuclear magnetic flowmeters designs developed for measuring hydrocarb...
2016
At the Karlsruhe Institute of Technology three high temperature liquid metal test facilities have been developed in the frame of the Helmholtz Energy Material Characterization Platform (HEMCP). The motivation for the usage of liquid metals is based on the innovative concept proposed for Concentrating Solar Power. The requirements for the qualification of new materials for high temperature applications on a long time basis could not be fulfilled by a facility with a single test section. Therefore, several universal scientific infrastructures, the SOdium Loop for TEst materials and Corrosion facilities (SOLTEC) have been designed, each facility having its specific test section. The core facility consists of two regions, the high temperature side with temperatures up to 1000 K connected to the test section and the low temperature side (up to ~773 K), where the pump and the main components are located. Nickel based steels are foreseen for the high temperature side, while conventional AI...
Journal of Applied Fluid Mechanics, 2015
The Computational Fluid Dynamics (CFD) study of external magnetic field effect on the steady, laminar, incompressible flow of an electrically conducting liquid-metal fluid in a pipe has been performed. The MHD Module of ANSYS Fluent commercial programme has been used to compute the flow and temperature fields. Na 22 K 78 (sodium potassium) alloy has been used as operating fluid, which is liquid in room temperature. The simulations are performed for two different cases, first a non-heated pipe flow and secondly an externally heated pipe flow. For both cases, three different magnitude uniform external magnetic field, B0, applied (which are B0 = 0.5 T, 1.0 T and 1.25 T, T represents Tesla). The results are compared for the MHD effect on the flow variables in two cases separately, but also compared for heated and non-heated cases in order to analyze the temperature effect on MHD flows, as well. It is observed that heating is reducing the magnetic effect on the flow field. While in nonheated cases it is observed that very well-known slowing down effect of MHD on fluid flow, in heated case the velocity field shows a tendency to behave as if it were MHD is not applied. Towards the end of the physical length the heating seems dominating the MHD effect. It is shown that in heated case temperature differences and entropy differences are in tendency to behave as if it were MHD is not applied.
International Journal of Heat and Mass Transfer, 2018
Liquid metal flows in rectangular ducts and circular pipes under high thermal loads and strong transverse magnetic fields are of great interest in context of developing cooling systems for fusion reactors. In this study, a downward flow of mercury in a uniformly heated pipe affected by a transverse magnetic field is studied experimentally. We show that moderate magnetic fields (0.2-1 T; Hartmann numbers 100-500) not only do not suppress the temperature fluctuations, but lead to the existence of significantly different regimes, characterized by strong temperature fluctuations. At least two different states of fluctuating flow exist. These states generate quantitatively different patterns of temperature fluctuation characteristics in the pipe cross-section. Domains of existence of both regimes are localized in the parameter plane Richardson versus Hartmann numbers. It is shown that these regimes are controlled by the Richardson number and disappear at high Hartmann numbers (above 500).
Magnetohydrodynamic pumps for molten salts in cooling loops of high-temperature nuclear reactors
Przegląd Elektrotechniczny, 2011
Possibilities of using the magnetohydrodynamic (MHD) effect for pumping molten salts in cooling loops of high-temperature nuclear reactors are analyzed. Two basic ways of producing magnetic field in the pump (saddle coils and permanent magnets) are evaluated with respect to the total Lorentz force and resultant pumping head of the device. The corresponding mathematical models are solved numerically Streszczenie. W pracy przeanalizowano możliwość zastosowania efektu magnetohydrodynamicznego (MHD) do pompowania płynnych soli w obwodach chłodzących wysokotemperaturowych reaktorów jądrowych. Zbadano dwa podstawowe sposoby wytwarzania pola elektromagnetycznego (cewki siodłowe i magnesy trwałe) pod kątem całkowitej siły Lorentza i wytwarzanego ciśnienia względnego. Do porównania wykorzystano numeryczny model efektu MHD. (Pompy magnetohydrodynamiczne do pompowania płynnych soli w obwodach chłodzących wysokotemperaturowych reaktorów jądrowych)
2020
Several technological applications involve the flow of liquid metals in ducts under a magnetic field, for instance, the coolants of fusion reactors. In this paper, using a magnetohydrodynamic MHD formulation based on the electric potential, we obtain an analytical solution for the flow of a liquid metal in a rectangular duct with two insulating walls and two perfectly conducting walls perpendicular to the applied uniform magnetic field. As the Hartmann number increases, the flow displays high velocities in the boundary layers attached to the insulating walls and a quasi-stagnant flow at the core. The effect of this flow pattern on the forced convection heat transfer is then explored numerically considering a uniform heat flux on either the conducting or insulating walls. Compared to the hydrodynamic case, the MHD flow enhances the heat transfer as the Hartmann number increases only in the case when the heat flux is applied at the insulating walls where high velocities are present. T...