## 6 Conclusions  
Thermal energy storage in the form of sensible and latent heat continues to be a way to address the mismatch between energy supply and demand. It has been identified as a very attractive strategy for high energy efficiency buildings. This paper reviews advanced research studies regarding sensible and latent heat thermal energy storage in porous media. The open-ended straight channel incorporating a porous medium (_copper foam_) and paraffin  
Figure 21: Time-averaged isotherm contours of mean flow around and through a permeable diamond-shaped cylinder at: (**a**) \(Re=50\) and (**b**) \(Re=150\) for various [PERSON] numbers [167], reprinted/adapted with permission from Ref. [167], 2022, Elsevier. (PCM) is the typical LHTES template. As metal foams and paraffin are the most widely used couple inPCMs and porous media, they are increasingly being used to improve heat transfer. The present review has focused on mesoscopic modeling approaches for single-phase and solid-liquid phase change heat transfer in porous media, which are widely involved in energy/environmental science and technology. This approach has experienced an amazing growth in the development of its methodologyand application over the past three decades showingdistinctive strengths over themacroscopic and microscopic numerical methods. Thereby, it bridged the gap between macroscopic methods dealing with Navier-Stokes equations and microscopic particle-based microscopic approaches such as the Monte Carlo and molecular dynamics methods. A brief introduction to three methods that can handle the fluid flows and heat transfer involved in a typical chosen LHTES model has been provided. Subsequently, two simulation methods, i.e.,the REV-scale method and pore-scale method, have beenselected and compared, and it is concluded that the REV-scale simulation is able to provide the flow and heat transfer features without the tedious effort in implementing the pore-scale approach. The REV-scale modeling has been shown to provide a sufficiently accurate prediction of most transport mechanisms in porous media, and as such, it can help to achieve efficient-design improvements of such systems. It should be stressed that for phase change heat transfer in porous media at the REV scale, the standard LB method must be modified to consider both the influence of the PCM and porous medium. Based on the literature, the following conclusions can bedrawn:  
* Through the bibliometric analysis that was carried out on TES methods, it is the LHS category that appeared to be the most relevant technique investigated. * SHS and LHS systems are most widely used systemsin different applications due to their high availability. However, most TCHS devices are not commercially available, except in a small range of applications, due to their unstable lifetime and high prices. * The SHS method has been widely used in solar applications where water is the most used material due to its low cost and high specific heat capacity. Note that porosity is one of the main parameters that influences the performance of any SHS system. * Despite their low thermal conductivity, PCMs can still be integrated into applications using various modes of incorporation, of which the impregnation of PCMs in porous structures appears to be the most relevant solution due to the high thermal conductivity engendered. * It turns out that PCMs can store an appreciable amount of energy which ismore than that ofSHSMs in a small relative storage volume. * Using foam metal in thermal energy storage can improve heat transfer rate while shortening charge/discharge periods. * Decreasing the porosity speeds up the melting phenomenon
* Increasing the PPI can enhance the forced convection heat transfer performance of the liquid PCM. * Pore-scale and REV-scale LBM approaches showed great potential for thesimulation of phase change phenomenon and sensible storage in a porous medium due to their inherent transienceand robustness to handle complexphysics.