Applications of Liquid Metals II

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Materials Science and Engineering".

Deadline for manuscript submissions: closed (25 March 2021) | Viewed by 7340

Special Issue Editor

Alma Mater Studiorum – University of Bologna, 40136 Bologna, Italy
Interests: liquid metals; turbulence model for liquid metals; heat exchange; fission and fusion reactors; finite element method; optimal control theory
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Special Issue Information

Dear Colleagues,

The purpose of this Special Issue on liquid metals is to bring together several aspects of this topic, acquire a sound basis of understanding, and provide an opportunity for discussion between those doing research in this field. Liquid metal materials are rapidly emerging as next-generation materials and many features of liquid metals such as the scattering of X-rays or neutrons, electromagnetic forces, electron metal screening, ion shielding, properties of solid metals, dynamics of fluids from inelastic neutron scattering, and electron energy level spectrum have gained extensive attention. Each liquid metal has its own peculiar characteristics. For example, lithium is the lightest of all metals and has the highest specific heat per unit mass. Lithium is characterized by large thermal conductivity and thermal diffusivity, low viscosity, and low-vapor pressure. Lithium is not only the most promising coolant for thermonuclear power installations but it also provides raw nuclear fuel to implement fusion reaction.

At room temperature, liquid metals display many unconventional properties superior to those of conventional metals while at high-temperature they are considered to be the most promising coolants. For heat transfer applications the thermal entrance length of liquid metals is relatively high leading to the flow never reaching a fully developed condition and higher Nusselt number values. The molecular properties of liquid metals are such that the thermal diffusion is faster than momentum diffusion with a Prandtl number less than one. The thermal boundary layer for liquid metal flow is not only confined to the near-wall region but also extends to the turbulent core region, which makes the turbulent structures important in the transfer of heat. Liquid metals are considered promising coolants for high-temperature applications, such as nuclear fission and fusion reactors, due to their high thermal diffusivity and excellent heat transfer characteristics. A good coolant should have a high melting point and avoid local boiling spots. The study of the surrounding magnetic fields that reduce the turbulence may also be important.

Liquid metals are important in several science fields. In bio-material engineering, room-temperature liquid metals display many unconventional properties superior to those of conventional ones and their outstanding, unique versatility opens many exciting opportunities for medical science. Moreover, the unique properties of liquid metals also enable many advanced bio-applications in the fields of drug delivery, molecular imaging, cancer therapy, and biomedical devices. In mechanical engineering, liquid metal corrosion problems need to be addressed to acquire a sound basis of understanding and to provide an opportunity for the development of liquid metal heat and power sources for special purposes, including heat-pipe systems, power systems, and liquid metal fast breeder reactor systems. In electronics, by combining the properties of metallic electrical conductivity, high surface tension, and low viscosity, some researchers have developed flexible components of electronic devices and microfluidic actuators. In chemistry, when liquid metals are used as a chemical reaction platform, the native-oxide skin, which appears on the surface of many liquid metals, is considered to be an excellent planar system to atomically form thin materials with extraordinary functionalities.

Prof. Dr. Sandro Manservisi
Guest Editor

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Published Papers (4 papers)

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Research

23 pages, 6701 KiB  
Article
Statistical Uncertainty of DNS in Geometries without Homogeneous Directions
by Jure Oder, Cédric Flageul and Iztok Tiselj
Appl. Sci. 2021, 11(4), 1399; https://doi.org/10.3390/app11041399 - 04 Feb 2021
Cited by 4 | Viewed by 1120
Abstract
In this paper, we present uncertainties of statistical quantities of direct numerical simulations (DNS) with small numerical errors. The uncertainties are analysed for channel flow and a flow separation case in a confined backward facing step (BFS) geometry. The infinite channel flow case [...] Read more.
In this paper, we present uncertainties of statistical quantities of direct numerical simulations (DNS) with small numerical errors. The uncertainties are analysed for channel flow and a flow separation case in a confined backward facing step (BFS) geometry. The infinite channel flow case has two homogeneous directions and this is usually exploited to speed-up the convergence of the results. As we show, such a procedure reduces statistical uncertainties of the results by up to an order of magnitude. This effect is strongest in the near wall regions. In the case of flow over a confined BFS, there are no such directions and thus very long integration times are required. The individual statistical quantities converge with the square root of time integration so, in order to improve the uncertainty by a factor of two, the simulation has to be prolonged by a factor of four. We provide an estimator that can be used to evaluate a priori the DNS relative statistical uncertainties from results obtained with a Reynolds Averaged Navier Stokes simulation. In the DNS, the estimator can be used to predict the averaging time and with it the simulation time required to achieve a certain relative statistical uncertainty of results. For accurate evaluation of averages and their uncertainties, it is not required to use every time step of the DNS. We observe that statistical uncertainty of the results is uninfluenced by reducing the number of samples to the point where the period between two consecutive samples measured in Courant–Friedrichss–Levy (CFL) condition units is below one. Nevertheless, crossing this limit, the estimates of uncertainties start to exhibit significant growth. Full article
(This article belongs to the Special Issue Applications of Liquid Metals II)
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13 pages, 2508 KiB  
Article
Numerical Analysis of the CIRCE-HERO PLOFA Scenarios
by Moscardini Marigrazia, Galleni Francesco, Pucciarelli Andrea, Martelli Daniele and Forgione Nicola
Appl. Sci. 2020, 10(20), 7358; https://doi.org/10.3390/app10207358 - 21 Oct 2020
Cited by 3 | Viewed by 2052
Abstract
The present work deals with simulations carried out at the University of Pisa by using the System Thermal Hydraulics code RELAP5/Mod3.3 to support the experimental campaign conducted at the ENEA (Energia Nucleare ed Energie Alternative) Brasimone Research Centre on the CIRColazione Eutettico—Heavy liquid [...] Read more.
The present work deals with simulations carried out at the University of Pisa by using the System Thermal Hydraulics code RELAP5/Mod3.3 to support the experimental campaign conducted at the ENEA (Energia Nucleare ed Energie Alternative) Brasimone Research Centre on the CIRColazione Eutettico—Heavy liquid mEtal pRessurized water cOoled tubes (CIRCE-HERO) facility. CIRCE is an integral effect pool type facility dedicated to the study of innovative nuclear systems and cooled by heavy liquid metal, while HERO is a heat exchanger heavy liquid metal/ pressurized cooling water system hosted inside the CIRCE facility. Beside the H2020 project Multi-Purpose Hybrid Research Reactor for High-Tech Applications (MYRRHA) Research and Transmutation Endeavour (MYRTE), a series of experiments were performed with the CIRCE-HERO facility, for both nominal steady-state settings and accidental scenarios. In this framework, the RELAP5/Mod3.3 code was used to simulate the experimental tests assessing the heat losses of the facility and analyzing the thermal hydraulics phenomena occurring during the postulated Protected Loss Of Flow Accident (PLOFA). The modified version Mod. 3.3 of the source code RELAP5 was developed by the University of Pisa to include the updated thermo–physical properties and convective heat transfer correlations suitable for heavy liquid metals. After reproducing the facility through an accurate nodalization, boundary conditions were applied according to the experiments. Then, the PLOFA scenarios were reproduced by implementing the information obtained by the experimental campaign. Sensitivity analyses of the main parameters affecting the thermofluidynamics of the Lead-Bismuth Eutectic (LBE) were carried out. In the simulated scenario, the LBE mass flow rate strongly depends on the injected argon flow time trend. The numerical results are in agreement with the experimental data, however further investigations are planned to analyze the complex phenomena involved. Full article
(This article belongs to the Special Issue Applications of Liquid Metals II)
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14 pages, 4199 KiB  
Article
STH/CFD Coupled Simulation of the Protected Loss of Flow Accident in the CIRCE-HERO Facility
by Pucciarelli Andrea, Galleni Francesco, Moscardini Marigrazia, Martelli Daniele and Forgione Nicola
Appl. Sci. 2020, 10(20), 7032; https://doi.org/10.3390/app10207032 - 10 Oct 2020
Cited by 6 | Viewed by 1888
Abstract
The paper presents the application of a coupling methodology between Computational Fluid Dynamics (CFD) and System Thermal Hydraulic (STH) codes developed at the University of Pisa. The methodology was applied to the CIRCE-HERO facility in order to reproduce the recently performed experimental conditions [...] Read more.
The paper presents the application of a coupling methodology between Computational Fluid Dynamics (CFD) and System Thermal Hydraulic (STH) codes developed at the University of Pisa. The methodology was applied to the CIRCE-HERO facility in order to reproduce the recently performed experimental conditions simulating a Protected Loss Of Flow Accident (PLOFA). The facility consists of an internal loop, equipped with a fuel pin simulator and a steam generator, and an external pool. In this coupling application, the System code RELAP5 is adopted for the simulation of the internal loop while the CFD code ANSYS Fluent is used for the sake of simulating the pool. The connection between the two addressed domains is provided at the inlet and outlet section of the internal loop; a thermal coupling is also performed in order to reproduce the observed thermal stratification phenomenon. The obtained results are promising and a good agreement was obtained for both the mass flow rates and temperature measurements. Capabilities and limitations of the adopted coupling technique are discussed in the present paper also providing suggestions for improvements and developments to be achieved in the frame of future applications. Full article
(This article belongs to the Special Issue Applications of Liquid Metals II)
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17 pages, 1511 KiB  
Article
A Logarithmic Turbulent Heat Transfer Model in Applications with Liquid Metals for Pr = 0.01–0.025
by Roberto Da Vià, Valentina Giovacchini and Sandro Manservisi
Appl. Sci. 2020, 10(12), 4337; https://doi.org/10.3390/app10124337 - 24 Jun 2020
Cited by 13 | Viewed by 1833
Abstract
The study of turbulent heat transfer in liquid metal flows has gained interest because of applications in several industrial fields. The common assumption of similarity between the dynamical and thermal turbulence, namely, the Reynolds analogy, has been proven to be invalid for these [...] Read more.
The study of turbulent heat transfer in liquid metal flows has gained interest because of applications in several industrial fields. The common assumption of similarity between the dynamical and thermal turbulence, namely, the Reynolds analogy, has been proven to be invalid for these fluids. Many methods have been proposed in order to overcome the difficulties encountered in a proper definition of the turbulent heat flux, such as global or local correlations for the turbulent Prandtl number and four parameter turbulence models. In this work we assess a four parameter logarithmic turbulence model for liquid metals based on the Reynolds Averaged Navier-Stokes (RAN) approach. Several simulation results considering fluids with P r = 0.01 and P r = 0.025 are reported in order to show the validity of this approach. The Kays turbulence model is also assessed and compared with integral heat transfer correlations for a wide range of Peclet numbers. Full article
(This article belongs to the Special Issue Applications of Liquid Metals II)
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