Abstract
The study of the thermal contact resistance at the liquid–solid interface is an important subject of the heat transfer of phase change materials. In this work, a fractal model for predicting the thermal contact resistance at the liquid–solid interface is established by considering the self-affine fractal geometry of the rough surface. Based on the fractal characteristic of roughness structures, topographical and mechanical analyses have been conducted to identify the position of the liquid–solid interface and determine the thermal contact resistance at the interface. The relationship between contact parameters and the thermal contact resistance are studied. Based on the analytical predictive model for thermal contact resistance at the liquid–solid interface, the three-dimensional melting process of a nanoparticle-enhanced phase change material with different thermal contact resistances was simulated by using the finite volume method, and the enthalpy-porosity model is employed. The effects of thermal contact resistance between the composite phase change material and the heat source are investigated. It is found that the augmentation of thermal contact resistance decreases the melting and heat transfer rates and the influence of thermal contact resistance becomes more pronounced with a higher volume fraction of nanoparticles.
Highlights
Latent heat thermal energy storage (LHTES) systems with phase change materials (PCMs) have been developed to avoid wasting excess energy
The low thermal conductivity of PCMs is the main weakness of LHTES, and it delays the thermal response to the phase change process
The thermal contact resistance at the liquid–solid interface plays a crucial role in the melting and solidification processes of phase change materials
Summary
Latent heat thermal energy storage (LHTES) systems with phase change materials (PCMs) have been developed to avoid wasting excess energy. The low thermal conductivity of PCMs is the main weakness of LHTES, and it delays the thermal response to the phase change process. Under this circumstance, several approaches to enhance the heat transfer capability of PCMs are developed, including using high thermal conductivity nanoparticles, high porosity metal foams, extended internal fins, and heat pipes.. A lot of studies have been conducted on the experimental characteristics of the TCR at the liquid–solid contact, the analytical model for predicting the TCR is still insufficient It is because the determination of a TCR is a triad problem generated by topographical, mechanical, and thermal problems. Yuan et al. proposed an improved model for predicting the TCR at the liquid–solid contact by combining the topographical analysis of Hamasaiid et al. and the mechanical analysis of the surface chemistry model. the model of Hamasaiid et al. and the following models, which are based on the statistical approaches for characterizing the surface topography, failed to consider the multiscale nature of the rough surface that should be characterized by scale-independent parameters
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