*A Review on Phase Change Materials for Sustainability Applications by Leveraging Machine… DOI: http://dx.doi.org/10.5772/intechopen.114380*

management to curb virus transmission. Building materials, like thick walls, are crucial for insulation, absorbing heat during the day and releasing it at night to maintain comfortable temperatures and mitigate temperature fluctuations in arid climates. Since the late 1980s, PCMs have been incorporated for efficient thermal management, absorbing excess heat to reduce temperature peaks.

This integration enhances energy density in building materials, reducing temperature spikes and HVAC energy needs, with PCM phase transition temperatures ideally between 20 and 30°C. Various PCM applications have been explored, including macro-encapsulated PCMs in gypsum boards, immersion in gypsum, mixing in concrete, and use in roofing, offering several strategies for improving thermal management in construction (**Figure 5**).

Through compression molding, Zhang et al. used microencapsulated PCM with gypsum and glass fiber. The results indicate that a mix of 50/50 composite gypsum board can absorb energy and moderate temperature rise for 48 mins and reduce peak temperature values to those of standard gypsum board. The major concerns with the use of PCM for buildings are availability, cost, additional weight, structural integrity, and suitable range of melting temperature afforded by PCM [49].

#### **2.4 Supplemental cooling in air-cooled power plant condensers**

Power plants, pivotal in electricity generation, necessitate efficient heat management, particularly in nuclear reactors, to ensure operational safety. Heat generated within a reactor core is dissipated into a water pool with submerged heat exchangers during maintenance. Without proper intervention, this can lead to thermal stratification, affecting the system's efficiency [50–52]. Utilizing adiabatic shrouds around heat exchangers can prevent such stratification [53, 54]. Moreover, incorporating PCMs in the pool's surrounding walls offers dual benefits: mitigating concrete damage and providing additional energy storage to postpone boiling. Given the extensive water and energy demands of conventional cooling systems, PCMs emerge as a vital innovation, exploiting their latent heat of fusion for significant thermal energy absorption during phase transition. This approach not only enhances cooling efficiency but also promotes sustainability by substantially reducing water consumption in power plant cooling operations.

#### *2.4.1 Thermal power plant*

Industrial cooling towers in thermal power generation are the largest consumers of freshwater. As energy demands continue to surge, the availability of freshwater for cooling purposes is expected to fall short, placing significant stress on freshwater resources. Consequently, there is a need for alternative technologies. One such alternative is dry cooling, utilizing air-cooled heat exchangers to eliminate the requirement for cooling towers. But the approach comes with trade-offs, including reduced operational efficiency, heightened capital and operational costs, and decreased reliability. In arid climates, air-cooled heat exchangers can become inoperative on scorching summer days when ambient air temperatures surpass the steam temperature at the turbine exhaust, resulting in power plant shutdowns and grid instability. To overcome this, supplemental cooling solutions like TES systems incorporate PCMs in LHTESS. It enhances performance and reliability, especially in areas with soaring daytime temperatures that exert backpressure on turbines and risk tripping failures.

#### **Figure 5.**

*Application of PCM in buildings: Encapsulated PCM (a) internally bonded, (b) sandwiched between concrete walls, (c) externally bonded, and (d) roofed and internally bonded room models.*
