Thermal energy storage using phase-change materials

Today, with the rapid growth of technology, the constant increase of energydemand has led the countries to carry out their energy supply security in various energy policies and researches. Especially in this last century, when energy has become a necessity rather than a luxury, every energy source has become one of the most basic necessities to be achieved in a simple way and to deliver quality to consumers with high quality, reliable and economical. In addition to the efficient use of energy, the topic of energy storage has also recently started to take its place among the energy policy headings of the countries. The studies related to latent heat energy storage realized with phase change materials have been intensified in the past ten years and continue to increase today. Phase change materials (PCMs) are defined as materials that allow storage in their own form in the form of heat energy. With increasing ambient temperature, the temperature of the material increases and when the temperature of the phase reaches the temperature of change, the phase changes. During this process, the material undergoes a phase change by passing through a higher energy source, thus storing a certain amount of heat. Subsequently, when the ambient temperature falls and the temperature drop in the field reaches below the phase change temperature, the material undergoes a phase change by passing through a lower energy source again, and the external heat is given to the internal heat. While there are many studies about phase change materials, there are many uses of these materials in the buildings such as passive and active heating-cooling applications, space applications, textile applications. In this study, eutectic FDMs consist of n-octadecane and n-hexadecane which have the potential to be used in low temperature thermal energy storage applications such as air conditioning systems and thermal control of the indoor temperatures in buildings were prepared for providing thermal comfort and conservation of energy. The prepared binary mixture is encapsulated shell which consists of styrene and divinylbenzene by reverse emulsification in micro size. In the series experiments, the effects of core/shell ratio and surfactant concentration on the thermal properties and encapsulation ratio of PCMs were investigated. As a result of thermal and morphological analyzes, the highest latent heat storage capacity (88 kJ/kg) were obtained in the highest core/shell ratio (2/1) and the lowest emulsifier ratio (45 mmol/L). Moreover the highest capsulation rate for this sample was found of 56,77%. The result of study showed that microencapsulated PCMs that have thermal energy storage capacities, phase transition temperature ranges and thermal stabilities can be used low thermal energy storage applications especially in the range of 18-30°C.