## 4 Studies on Using Inorganic PCM in Concrete for Thermal Energy Storage
Heat transmission was shown to be consistent and rapid along all radial planes, as seen by the spatial differences in temperature; however, as one moves down the length of the CTES module, the heat transfer rate decreases progressively owing to a decline in Heat Transmission Fluid (HTF) temperature. The parametric study revealed that a 40 \({}^{\circ}\)C shift in input temperature at a constant air velocity of 2 m/s resulted in a 48% and 29% reduction in charging and discharging times, respectively. Concrete composed of macro-encapsulated inorganic PCM-lightweight aggregate (PCM-LWA) was studied by [PERSON] et al. (2020) [72] to investigate whether a dual-layer coating technique might be used to increase leakage and corrosion resistance. The term \"thermal energy storage aggregate\" (TESA) is used to describe the coated PCM-LWA system. Compressive strength tests revealed a 6-9% decrease in TESA concrete when compared to LWA concrete (Figure 8). The thermal dependability of the TESA system is shown by the fact that TESA concrete did not suffer any strength loss after being exposed to temperature cycles between 15 \({}^{\circ}\)C and 40 \({}^{\circ}\)C. The analysis of differential scanning calorimeters as well as thermogravimetrics confirmed the PCM's thermal stability and dependability. The results of the thermal performance test validated the viability and utility of TESA for use in concrete buildings. The surface temperature of TESA concrete was found to be lower than that of the control mixture using an infrared thermography camera. Figure 7: PCM Aggregate Replacement Percentage versus Heat Storage [70]. To reduce the summertime temperature peak and boost the financial viability of renewable energy systems, [PERSON] et al. (2020) [73] created a novel phase variation foam concrete having a low thermal conductivity as well as an optimum temperature of phase variation. This research used the adsorption technique, in which paraffin was absorbed by fumed silica to generate composite PCM. This research determined that the composite PCM with a paraffin content of 45 wt.% had the greatest adsorption capacity and setting performance through morphology and liquid leakage tests. The suggested composite PCM inside the concrete was measured using a differential scanning calorimeter (DSC), and it was found to have an appropriate temperature of phase variation (around 41 \({}^{\circ}\)C) as well as phase variation latent heat (the procedure of endothermic is \(113.3\) J/g and the procedure of exothermic is \(-112\) J/g) for preventing excessive heat buildup in the summer. Using a unique coreshell structured phase change material aggregation (AGGsPCM), [PERSON] et al. (2020) [74] were able to absorb and store solar energy in the building envelope for space heating and cooling. Testing of AGGsPCM's thermophysical characteristics and thermal performance in a concrete panel was performed in the real world under southern Chinese climatic conditions. The findings show that the PCM leakage can be stopped and the concrete panel's thermal performance can be significantly improved. An increase in thermal comfort and possible savings on power bills resulted from the AGGPCM-concrete panel's ability to lower peak temperatures by 1 \({}^{\circ}\)C. Increasing the amount of MPCMs in AGGsPCM or choosing a PCM with a more appropriate phase transition temperature might improve the performance by facilitating a more effective heat storage and release procedure. The efficacy of a Textile-Reinforced Concrete (TRC) composite adapted via the inclusion of PCMs was the subject of a multi-physics study published by [PERSON] et al. (2021) [75]. The promise of this composite material comes from the fact that it combines the low weight of TRC with the high heat storage capacity of PCMs. Mechanical and thermal assessments were made on the novel idea of a PCM-TRC slab and the result of reinforcing a PCM-adapted matrix with a textile grid. Slabs made of PCM-TRC retain their ductile and multi-cracking behaviours despite a decline in their mechanical performance.