## 4 Studies on Using Inorganic PCM in Concrete for Thermal Energy Storage
The paraffin-magnetite combination, paraffin, and PEG were melted and poured into the copper tubes. Melting point, latent heat, thermal conductivity, and phase transition are only a few of the properties of PCMs that were studied. When compared to pure paraffin (0.32 W/m \({}^{\circ}\)C) and PEG (0.28 W/m \({}^{\circ}\)C), the addition of magnetite particles in paraffin may increase the thermal conductivity to 0.53 W/m \({}^{\circ}\)C. All three of these properties (melting point, latent heat, and thermal conductivity) played a role in how the PCMs behaved throughout their melting phase. [PERSON] et al. (2023) [80] employed PCMs in environmentally friendly mortar to increase its thermal energy storage capacity and physico-mechanical characteristics by adding PCMs at concentrations of up to 50% of the cement content in lieu of sand. Twelve samples were made by combining cement and 100% natural sand to make mortars containing 0%, 12.5%, 25%, and 50% PCMs. The authors created eight distinct combinations, varying the percentage of ceramic fine aggregate from 25% to 50%, 75% to 100%, and the percentage of PCMs from 25% to 50%. Compressive strength was found to increase by 37.1% when ceramic was substituted for sand, while temperatures were found to decrease to 9.5 \({}^{\circ}\)C, and phase peaks were shifted ahead by 115 min for a mix of 50% PCM + 100 CFA (ceramic fine aggregates) compared to 7.0 \({}^{\circ}\)C, and phase peaks were shifted ahead by 85 min for a mix of 50% PCM + 100 NS (natural sand). Table 2 presents a summary of research on inorganic PCMs used in concrete for thermal energy storage. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Authors (Year)** & **Configuration/Composition** & **Type of Study** & **Studied Parameters** & **Results/Findings** \\ \hline \multirow{6}{*}{[PERSON] et al. (2018)} & \multirow{2}{*}{Form-stable hydrate salt} & \multirow{2}{*}{Experimental} & \multirow{2}{*}{Impact of incorporation of form-stable hydrate salt PCMs} & Despite a drop in mechanical strength due to the incorporation of form-stable hydrate salt PCMs, thermal energy storage \\  [67] & & cement mortar. & & \\  & & & energy storage. & \\  & & & & \\  & & & & \\ \hline \multirow{6}{*}{[PERSON] et al. (2018) [68]} & \multirow{2}{*}{A wooden box with infrared radiators and a chiller for testing several shapes of phase-change packaging, including cubes, cylinders, plates, and spheres.} & \multirow{2}{*}{Numerical and experimental} & Effects of thermal shading and uniform PCM dispersion inside concrete blocks. & Reduced heat transfer into interior spaces is achieved by the use of thermal shading and uniform PCM dispersion inside concrete blocks. \\ \hline \multirow{6}{*}{[PERSON] et al. (2018) [69]} & \multirow{2}{*}{Microencapsulated phase change materials (PCMs)} & \multirow{2}{*}{ \begin{tabular}{c} Microencapsulated phase change materials (PCMs) are being incorporated \\ experimental \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} Microencapsulated phase change materials (PCMs) are being incorporated into new textile reinforced concrete panels, which \\ come in a wide range of mix patterns. \\ \end{tabular}  } \\ \hline \multirow{6}{*}{[PERSON] et al. (2019) [70]} & \multirow{2}{*}{ \begin{tabular}{c} Phase change material \\ concrete (pt to roughly \\ 7.8\% by weight of concrete). \\ \end{tabular}  } & \multirow{2}{*}{Experimental} & \multirow{2}{*}{ \begin{tabular}{c} Effect of incorporating phase change material (PCM)-heavy, lightweight concrete on the concrete’s characteristics. \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} As the percentage of PCM aggregate rises, the mechanical characteristics seem to improve. It was discovered that when the PCM aggregate replacement rate increased, so did the latent heat. \\ \end{tabular}  } \\ \hline \multirow{6}{*}{[PERSON] et al. (2019) [71]} & \multirow{2}{*}{ \begin{tabular}{c} An efficient concrete thermal energy storage \\ (CTES) technology. \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} Numerical and experimental \\ \end{tabular}