Insulated Solar Electric Cooker with Phase Change Thermal Storage Medium

This final design review document outlines the senior design project carried out by a team of four mechanical engineering students at the California Polytechnic State University – San Luis Obispo under the sponsorship of Dr. Peter Schwartz of the Cal Poly Physics department. The aim of this project was to improve upon the design of previously developed Insulated Solar Electric Cookers (ISECs) by adding a thermal storage system to allow for quicker cook times and the ability to cook food at non-peak solar hours. The team’s goal was to develop a working prototype utilizing a phase change medium as the thermal storage system by the end of the 1-year project that would be tested against other contemporary, inexpensive cooking systems. The team was able to successfully design, manufacture, and test two functioning prototypes. The final design utilized diodes connected to a solar panel as the heating element due to their extremely low cost as well as their thermal properties. The phase change material selected for thermal storage was a sugar alcohol known as erythritol. The final prototype could boil 1 liter of water in under 20 minutes with a device efficiency of 35% and continued to store energy for over 4 hours. As a result, the ISEC with thermal storage exceeded or met all but one of the design requirements as it was unable to completely melt the erythritol in the allotted time. A discussion of these successes and possible solutions to this shortcoming are also discussed within this report. This document presents the summation of the team’s work on the project from the project scope to the finished results and the process used to achieve these results. This document has been presented to Dr. Schwartz for review and approval