Resumen de Analysis and implementation of thermal energy storage using phase change materials for cooling applications
This thesis studied the benefits of thermal energy storage using phase change materials in buildings. The drastically increase on the energy demand, the energetic dependence on exhaustible fossil fuels and the climate change result in a new worldwide energetic scenario. Energy efficiency will play a key role in the near future, especially in the construction sector which represents an important part of the total energy consumption of our society. Moreover, the new comfort standards and the high penetration of the cooling systems in new and refurbished buildings present an additional and increasing problem, especially in regions with warm climates.
This new situation can favour the introduction of PCM in buildings for a higher energy efficiency and thermal comfort. Furthermore, the new Spanish regulation that fosters energetic efficiency in buildings may be a good opportunity for PCM application. It is also important to remark that the introduction of this technology in the construction sector would multiply product sales and thus decrease the price of the PCM.
The thermal behaviour of five real cubicles located in Puigverd de Lleida (inner region of Catalonia, northeast of Spain) was studied. The meteorological conditions are those of typical continental climate in Spain, similar to Madrid, with cold winters, hot and relatively dry summers, and important temperature oscillations between day and night. Different constructive solutions used in the Mediterranean countries (conventional brick and alveolar brick) were experimentally tested with and without PCM.
Results showed that the use of PCM could smooth-out the daily fluctuation of the indoor air and the wall temperatures and improve the operative comfort temperature. Moreover, the energy consumption during the warm seasons was significantly reduced.
Numerical simulations were done to validate two commercial programs: PCM express and EnergyPlus. The numerical results did not match with the experimental ones and the accuracy of the PCM simulation was not satisfactory. Improvements must be done in the simulation tools to fairly represent the thermal behaviour and energy improvements achieved experimentally by the use of PCM in buildings.
