## 2 Sensible Heat Storage (SHS) Method
### Sensible Heat Storage in Porous Media  
Without detailing, the SHS mode consists of a sensible heat storage material (SHSM), an SHSM container (e.g., _tank_) to prevent leakage and heat losses and input/output devices [47].Among the tools used in this storage mode, SHS in a porous medium is the most preferred solution. Out of the available case studies in the literature in this field, a few representative ones are reviewed in the present section. Saturated tanks of porous solid SHSMs are used in many industrial and building applications such as power generation \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**SHSM**} & \multirow{2}{*}{**Type**} & **Density** & **Thermal** & \multirow{2}{*}{**Specific Heat**} \\  & & **(kg\(\cdot\)m\({}^{-3}\))** & & **Conductivity** & **(kJ\(\cdot\)m\({}^{-1}\cdot\)K\({}^{-1}\))** \\ \hline Water (80 \({}^{\circ}\)C) & Liquid & 970 & 0.67 & 4.19 \\ Water (40 \({}^{\circ}\)C) & Liquid & 990 & 0.63 & 4.19 \\ Water (10 \({}^{\circ}\)C) & Liquid & 1000 & 0.6 & 4.19 \\ Oil & Liquid & 880 & 0.14 & 1.88 \\ Ethanol & Liquid & 790 & 0.171 & 2.4 \\ Propanol & Liquid & 800 & 0.161 & 2.5 \\ Butanol & Liquid & 809 & 0.167 & 2.4 \\ Ceramic brick & Solid & 1800 & 0.73 & 0.92 \\ Rock & Solid & 2800–1500 & 3.5–0.85 & 1 \\ Concrete & Solid & 2000 & 1.35 & 1 \\ Wood & Solid & 700–450 & 0.18–0.12 & 1.6 \\ Aluminum & Solid & 2707 & 204 & 0.896 \\ Copper & Solid & 8954 & 385 & 0.383 \\ Granite & Solid & 2640 & 4.0–1.7 & 0.82 \\ Sand and gravel & Solid & 2200–1700 & 2 & 1.18–0.91 \\ Clay or silt & Solid & 1800–1200 & 1.5 & 2.5–1.67 \\ Limestone & Solid & 2600–1600 & 2.3–0.85 & 1 \\ Cement mortar & Solid & 1800 & 1 & 1 \\ Brick & Solid & 1600 & 1.2 & 0.84 \\ Marble & Solid & 2500 & 2 & 0.88 \\ Plastic board & Solid & 1050 & 0.5 & 0.837 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Thermophysical properties of some commonly used SHSMs [3, 18, 19, 41], reprinted/adapted with permission from Refs. [18, 19], 2022, Elsevier. Figure 6: Most available and common SHSMs, reprinted/adapted with permission from Ref. [18], 2022, Elsevier. and heating [3]. Figure 7 exemplifies a residential heating application using a porous fixed bed storage tank. In general, a fixed bed storage tank is used for the TES of solar air heaters and represents a volume of porous medium formed by packing particles of selected SHSM into a container. In this system, the working fluid (e.g., _air_) advects heat from the collector to the reservoir. Hot fluid passes through spaces between solid SHSMs (e.g., _rock or sand_), causing the particles to rise in temperature during the day (_charging loop_), and the quantity of sensible heat stored inside the tank is recovered during the night (_discharging loop_). Let us point out, however, that the main parameters that influence the SHS system performance are the working fluid type, the flow rate and the porosity [3, 47]. A huge range of investigations in the literature have dealt with SHS in various porous units. Among the different characteristics of a sensible storage medium, the porosity effect, which turned out to be a crucial characteristic, is sketched herein. To address this topic, [PERSON] et al. [48] developed a numerical model to study the effect of pore density parameter (PPI) on an SHS unit. The system deemed was subjected to forced convection and compared to an LHS unit. They advised a porous metal foam to optimize energy and exergy efficiencies while indicating that increasing the PPI for high porosity value mitigates energy losses for sensible heat systems and thereby increases the quality of stored energy. In another study, [PERSON] et al. [49] explored the charging and discharging process enhancement in a porous SHS duct held under a forced pulsating flow. They examined several porosities of the porous support while estimating its thermal performance. They found that with increasing porosity, the sensible energy amount stored is improved, and the exergy efficiency (_quality_) is significantly raised.