Description
The Metal Alloy Thermal Energy Storage System (MATESS) is a project being developed in the Combustion and Solar Energy Laboratory which uses aluminum-silicon alloys as latent heat thermal energy storage for a concentrated solar power system. A prior student partially constructed a lab-scale prototype to melt and freeze alloy samples in an alumina cylinder with a propane burner and compressed air in order to validate the concept. During the course of this thesis, the lab-scale prototype was developed further with modifications to improve functionality and correct problems. Lighter lids were constructed to ease transitions during testing and accommodate a change in facilities. A temperature control circuit was added to regulate the electric heating system. An instrument panel was built to house all measurement and control components. Fixes were made to repair the damaged frame, protect the concrete shell from thermal shock, and restore many damaged thermocouples. Extensive numerical analysis was undertaken on four alloys to form performance estimates for experimental tests and to examine anticipated behavior. Fluent was selected as the simulation tool, though it was later found to be incapable of properly modeling solid sinking behavior during a melt. Natural convection behavior was examined and found to produce motion in the liquid alloy but no significant changes to heat transfer. The enthalpy- porosity mushy zone constant was varied but found to have little effect on the behavior of the system. Air flow rates were varied but found to have only a minor effect on thermal efficiency.
