Thermal stability of organic fluids for Organic Rankine Cycle systems

Each organic fluid is characterized by thermal decomposition above a specific temperature called the thermal stability limit. The correct evaluation of this limit is extremely important to avoid massive cracking phenomena which can cause the fouling of heat exchangers' surfaces, material erosion, and changes of fluid thermodynamic properties. After a brief discussion about the mutual correlation between the chemical structure and the thermal stability of working fluids, a review of the main experimental data available is worked out. Finally, experimental apparatus and a useful methodology to determine temperature limits for the working fluids is presented and discussed.