Thermal Storage Systems are receiving more attention in recent years due to an increased use of renewable energy sources. As most renewable energy sources have limited availability with time, it is important to store any excess energy that is produced so that it can be used when needed. Conventional heat storage systems make use of sensible heat storage, typically using water as the heat storage medium. This project explores using latent heat for thermal energy storage. This can be accomplished by using phase change materials as the storage medium for the system. Phase change materials are generally defined as any substance that experiences a phase change in the operating temperature range of the system.
The project looks at several different waxes as potential phase change materials to be used in a hybrid sensible, latent heat storage system. Significant research has been conducted on paraffin wax as a phase change material, this project considers paraffin wax as well as several sustainable waxes such as palm wax, beeswax, and soy wax, to be used as a storage medium. Several benchmark experiments were conducted on the various waxes. Experiments include looking at the cooling curves of the different waxes, the melting points of the different waxes, as well as the specific heat and latent heat of fusion of the waxes in consideration. The specific heat and latent heat of fusion were found using a differential scanning calorimeter (DSC). Palm wax was chosen to be used in the thermal storage system due to its availability and sustainable properties as well as having similar properties to paraffin wax.
After choosing a thermal storage material, a prototype storage system was designed and built. The intent of the system is to create a hybrid sensible latent heat storage system that can be used for storage of excess thermal energy produced by a solar thermal collector. The prototype latent storage unit consists of a one gallon metal container with copper tube running through the container, the container is then filled with palm wax. Experiments will be conducted with several different configurations of the latent and sensible storage system in order to determine the configuration that will allow for the most amount of energy to be stored in the overall system.