Bio inspiration, biochemical materials and methods in thermal energy storage

Today, energy production is heavily dependent on fossil fuels. The current problems like climate crisis and energy security make efficient renewable energy applications more important. Thermal Energy Storage (TES) systems provide uninterrupted use of renewable energy resources. Among the TES systems, latent heat storage method that uses Phase Change Materials (PCM) with high storage capacity is started being used commonly. PCMs can be used for heating, cooling and temperature control TES systems. In nature, especially warm-blooded living beings have to keep their body temperatures at the optimum temperature in which their organs and systems can work in order to survive. For this reason, they have undergone process esof adaptation for hundreds of years and have continued their lives. In this thesis, PCMs and their composites and systems for TES were developed with bio-inspiration from temperature control of warm-blooded living beings. Like all mammals living in cold oceans, whales have a 'blubber' tissue in their bodies for body temperature control. Previous studies show that fatty acids with high concentration in blubber are oleic acid, palmitic acid, stearic acid and myristic acid. Using these fatty acids and oleyl alcohol, which is also found in 'blubber', seven different PCMs were developed. By incorporating PCMs in hydrogels as support materials to prevent their leakage during phase change, form stable PCMs were achieved. The best hydrogel option was determined as PVA with its stability and anti-leakage property. Four different type of heat exchanger without any pipes was designed using the developed form stable composite with 25% PCM. Results of TES experiments with these systems showed that efficiency values of 67%-82% can be achieved. These results show that PVA/PCM composite pipeless heat exchanger can be promising for more efficient and economic TES applications. This study showed that designs bio-inspired from perfect examples in nature can lead to more innovative and efficient advances.