Liquid Metals as Efficient High‐Temperature Heat‐Transport Fluids

Abstract

Liquid metals appear to be attractive heat‐transport fluids, in particular if looking at their high thermal conductivities and low viscosities. Despite some pioneering technical applications in the past, complex handling, special requirements, safety concerns, and structural degradation of the materials have prevented their widespread application. However, progress in research and development on liquid‐metal science and technology has advanced considerably in the last decade, and this has opened the gate to their broader use in the short term. This requires a more differentiated view on liquid metals, particularly on the specific properties of individual fluids within the context of specific applications. By doing so, many commonly mentioned prejudices vanish or are of minor significance. At the Karlsruhe Institute of Technology, a comprehensive research program on liquid‐metal technology has been pursued for more than 50 years, and some of the advances in different applications will be outlined in this article.

The influence of the cell inclination on the heat transport and large-scale circulation in liquid metal convection

“…Furthermore, turbulent thermal convection in liquid metals (Pr 1) is relevant in engineering applications, especially in cooling systems of tokamaks and fast breeder reactors (Zhilin et al 2009;Belyaev et al 2013). Liquid sodium is of particular interest because of its very low Prandtl number (Pr ≈ 0.009) and it is widely used as cooling agent in fast neutron reactors (Heinzel et al 2017).…”

Liquid metals, materials and safety measures to progress to CSP 2.0

“…Technical solutions for the safety challenges of sodium used in high temperature applications are presented and advanced materials, which are presently under development and investigation at KIT. Also, new ideas are presented to extend the temperature range [1], [2] as well as proposals for dual systems including a topping system based on AMTEC [3]. The paper describes the safety oriented design as realized in the KASOLA facility [4] and gives hints for scale up to industrial size systems, especially for temperatures up to 900°C [5], [6] including different thermal energy storage options [7].…”

“…Options for fast return to operation in case of failures are under discussion, to reduce HTF caused outages. The excellent heat transfer characteristic [2] and the required safety provision have to be taken into account to design receiver, heat exchanger and storage tanks. Finally, accident mitigation measures are discussed based on pre-emptive measures [8] including spreading of sodium aerosols taking credit from KIT's CDIM (Center of DIsaster Management) [9].…”

Thermodynamic Analysis of High‐Temperature Energy Storage Concepts Based on Liquid Metal Technology

“…As described in previous studies, LMs such as lead, lead‐bismuth eutectic (LBE), or sodium are attractive heat transfer fluids (HTFs) due to their beneficial thermophysical properties, in terms of high thermal conductivity and an extensive temperature range up to 1500 °C. Consequently, LMs are most convenient in applications at high thermal loads, as it was shown in nuclear and concentrated solar power (CSP) systems, see, e.g., a previous study . In the past decades, extensive R&D work has been devoted to better understand the thermal‐hydraulic behavior of these fluids, as well as the compatibility with structural materials, with significant progress in recent years.…”