Design and performance Evaluation of solar thermal baking system using Scheffler reflector integrated with basalt rocks as energy storage for household

Abstract

This study investigates the use of a solar thermal baking system with a Scheffler reflector and basalt rocks as an energy storage medium to meet the increasing energy demands for baking while minimizing environmental impact. The research includes design, manufacture, experimental performance evaluation, and simulation of the system. A Scheffler reflector with 6.8 m² surface area and 1.4 m focal length was designed and manufactured for baking 2.6 kg of dough in one cycle. The installation of a Scheffler reflector in a specific location requires consideration of several factors based on findings from COMSOL simulations. These factors include true north, polar axis, declination angle, and hour angle, and they all have a significant impact on performance. According to the baking capacity requirement, a 95*70*70 cm³ oven working with natural convection was designed and manufactured. The findings from ANSYS simulations have revealed an important aspect to consider when placing bread in the oven. It is not recommended to place the same amount of bread on both the top and bottom trays of the oven, as this can lead to uneven baking due to differences in heat distribution. Furthermore, it is advised to not place both trays in the same direction inside the oven, as this can also result in a lack of uniformity in baking. The highest temperature recorded on the receiver surface during the unloaded test was 303°C at 1:15 PM, with an irradiance of 855 W/m2 . The bread baking test showed that the oven has an overall efficiency of 42% at an average solar irradiance of 838 W/m2 . Based on the design, using the Scheffler reflector for bread baking, it is estimated to save up to 3.5 tons of CO2 emissions and 7564 ETB in electricity costs annually. The Scheffler reflector is an environmentally friendly and cost-effective solution that can help to reduce carbon emissions and save money on energy consumption.