Proceedings of the International scientific and practical conference ―Multidisciplinary approaches in science, technology and culture‖ (September 5-7, 2025) / Publisher website: www.naukainfo.com. – Oxford, United Kingdom, 2025. - 124 p.

118 INTRODUCTIONAL Maintaining stable temperatures in agricultural structures such as greenhouses, pigsties, and poultry houses is crucial for productivity. During nighttime and winter, significant heat losses occur—up to 85% of a greenhouse‘s heat can dissipate overnight [1]. This leads to increased heating costs, which may account for 20–25% of total operating expenses in cold climates [2]. In addition to economic losses, sharp temperature fluctuations cause stress in plants and animals, reducing yields and productivity. Conventional methods—insulation and active heating—either only slow down heat loss or require high energy input. An alternative approach involves thermal energy storage systems that absorb excess heat during the day and release it at night. While water is commonly used due to its high specific heat capacity, phase change materials (PCMs) offer significantly greater energy density by storing latent heat. This makes them a promising solution for improving thermal regulation in agricultural facilities. PHYSICAL PRINCIPLES OF PHASE CHANGE THERMAL ENERGY STORAGE When a substance undergoes a phase change (e.g., from solid to liquid or vapor to liquid), it absorbs or releases a significant amount of energy—known as the latent heat of phase transition—while maintaining a nearly constant temperature. This principle underlies the operation of phase change thermal energy storage (TES) systems: materials absorb excess heat during melting and release it during solidification. This approach allows for energy storage densities significantly higher than those of sensible heat systems. For instance, paraffin waxes store about 180–230 kJ/kg of latent heat—five times more than water cooled over the same temperature range. Even small masses of PCM can noticeably reduce indoor temperature fluctuations [3].