Insight into the complicated energy-mass transfer and hierarchical reaction in metallurgical industry is of particular value in improving productivity and reducing energy consumption. This work proposes a coupled multiphysical reaction-transport (c-MPRT) model that is based on the implicit finite difference method for the promising bisolid porous pellet to investigate its dynamic characteristics concerning heat transfer, chemical reaction, and phase change. This model successfully reveals a negative influence on the heat conduction from the outer layers to the inner layers of the pellet, due to the enormous heat absorption of the chemical reacting and physical melting process. Compared to the ex situ heat conduction, the in situ Joule heat plays a dominant role during the heating of the inner layers. Additionally, there appears to be a decline in the temperature in the inner layers of the pellet during the reaction process, corresponding to a decreasing reaction rate resulting from the insufficient energy input to the inner layers. The maximum decrement in the temperature and the reaction rate are 35 K and 7.86 mol/s, respectively. In contrast with the chemical reaction process, the fusion process costs less time because the latent heat is lower than the enthalpy of the chemical reaction. It was found that a critical time point at which the fusing region enlarges abruptly exists and is about 1230 s, while the entire multiprocess in the pellet consumed about 1477 s. This coupled multiphysical model contributes to revealing the reaction-transport details and is of great significance to the bisolid porous pellet.

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As a core element in solar parabolic trough collector, the evaluated receiver often runs under severe thermal conditions. Worse still, the transient thermal load is more likely to cause structural deformation and damage. This work develops an efficient transient multi-level multi-dimensional (M2 ) analysis method to address photo-thermal-elastic problems, thereby estimating transient thermal load and deformation for the receiver:model is adopted to determine the transient thermo-hydraulic state, (ii) 3-D finite volume method (FVM) model for the receiver tube is established to obtain the real-time temperature distribution, (iii) 3-D finite element method (FEM) model is employed to make thermoelastic analysis. Based on this M 2 method, the typical transient cases are conducted in cold-start, disturbed-operation and regulatedprocess. Three indicators (average temperature of the wall (ATW), radial temperature difference (RTD), circumferential temperature difference (CTD)) are defined for overall analysis of the receiver thermal load. It is found that in the transient process, receivers face response delay and endure significant thermal load fluctuation. The response time for a single HCE (heat collecting element) under lower mass flow rate (1.5 kg s −1 ) could sustain 280 s. During the cold-start stage (DNI=200 W m −2 to 800 W m −2), the maximum value of CTD in receiver is as high as 11.67°C, corresponding to a maximum deflection of 1.05 cm. When the mass flow rate decreases sharply by 80%, the CTD reaches 33.04°C, causing a 2.06-cm deflection. It should be pointed out that in the cold-start stage and the lower mass flow rate operation for solar parabolic trough collector, alleviating the transient thermal load and deformation is of importance for safely and efficiently running evaluated receiver. solar energy, transient thermal load and deformation, heat collecting element, parabolic trough collector, multi-level multi-dimensional analysis method

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