Effect of nano-coating on corrosion behaviors of DCLL blanket channel Huang Hulin ⇑ , Yin Shimou, Ahmed Fawad College of Astronautics, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016, China article info Article history: Received 24 April 2019 Received in revised form 13 June 2019 Accepted 28 June 2019 Keywords: Dual coolant liquid blanket Non-wetting nanomaterials Discrete phase model Corrosive behavior Heat and mass transfer characteristics abstract The corrosive behaviors of liquid metal fluid flow on the channel wall of Dual Coolant Liquid (DCLL) blan- ket of fusion reactor were simulated by imposing the discrete phase model (DPM) under different mag- netic field strength, inlet velocities and neutron heat sources while considering blanket channel walls with and without non-wetting nanomaterial coating conditions. Results showed that regardless of the external environment of the blanket (except in the absence of magnetic field), the corrosion of the inner walls of the blanket channel declined significantly after employing nano-coatings in comparison to that of uncoated wall. For the uncoated condition, channel wall corrosion rate increased exponentially with time, various parameters have significant influence on channel corrosion, and the effect of magnetic field intensity is highest among them. In contrast, the corrosion rate of the channel walls with nanomaterial coating increased linearly with time, and unlike uncoated wall there is little difference on the corrosion rate of the channel walls for different parameters. Hence, these minute alterations in the corrosion of the channel walls with varying parameters indicate that the nanomaterial coating layer has a substantial pro- tective effect on the blanket wall structure. Ó 2019 Elsevier Ltd. All rights reserved. 1. Introduction Fusion nuclear energy is considered a new technological method that can permanently solve energy problem. International research on magnetic confinement nuclear fusion began in the 1950s, and went through the path of fast pinch, magnetic mirror and imitation star in the exploration of the feasible way for mag- netic confinement nuclear fusion [1]. The component that plays a key role for energy conversion in the fusion apparatus is the blan- ket. How to efficiently convert the nuclear energy into heat energy for power generation under the premise of safety is a key problem to be solved in the blanket design [2–4]. The liquid metal blanket (such as liquid lithium lead (Pb-Li17)) is a main candidate for fusion reactor because of its high tritium production and easy heat extraction characteristics ever since the concept of magnetic con- finement fusion has been proposed. Among the various liquid blan- ket, the dual coolant liquid lithium lead blanket has been considered as the most promising blanket [5]. The lithium in the DCLL reacts with neutrons to generate a large amount of heat and forms a non-uniformly distribution neutron heat source, which is absorbed by working fluid of liquid Pb-Li17 in the blanket and helium is employed to cool the blanket structures made of spe- cial stainless steel [6,7]. High temperature in the blanket affects its material’s physicochemical properties and reduces its service life, but it is also imperative to rise the outlet temperature of the work- ing fluid for increasing the energy conversion rate. At the same time, the non-uniform distribution of neutron heat source and strong magnetic field in DCLL channel have an extreme impact on the corrosive behavior and flow erosion mechanism on wall structure materials while liquid metal fluid flows in the DCLL chan- nel. So, for most of the self-cooling and double-cooling blanket using Pb-17Li, the strong MHD effect caused by the interaction of induced current with magnetic field in the fluid and the corrosion of the blanket structure by MHD effect are also two very noticeable problems. So, MHD effect for heat transfer have been widely inves- tigated [8]. In order to solve these problems, a kind of flow channel insert (FCI) made of carborundum had been proposed to separate the channel to main flow area and gap flow due to the low electri- cal conductivity and low thermal conductivity of the FCI to reduce the channel induction current and the energy loss, which declined the MHD pressure drop and improved the thermal efficiency of the blanket [9–11]. Although the use of the FCI reduces the jet flow in the mainstream and the corrosion is mitigated to a certain extent, the FCI causes strong flow instability of the gap flow, and even the occurrence of turbulence, then the local corrosion of the channel wall surfaces is aggravated [12]. Therefore, the wall structure material of the DCLL blanket not only suffers from the erosion of liquid metal flow in the channel, but also suffers from fatigue and creep damage, and withstand high temperature, high flux https://doi.org/10.1016/j.ijheatmasstransfer.2019.06.102 0017-9310/Ó 2019 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: hlhuang@nuaa.edu.cn (H. Hulin). International Journal of Heat and Mass Transfer 141 (2019) 444–456 Contents lists available at ScienceDirect International Journal of Heat and Mass Transfer journal homepage: www.elsevier.com/locate/ijhmt