2026-09-21T21:02:48Zhttps://repository.unam.edu.na/server/oai/request

oai:repository.unam.edu.na:11070/42742026-06-27T22:01:13Zcom_11070_3406com_11070_3311com_11070_3304col_11070_87

Chiguvare, Zivayi Naule, Cecilia N. 2026-06-24T11:35:23Z 2026-06-24T11:35:23Z 2025 http://hdl.handle.net/11070/4274 A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Science in Renewable energy This thesis presents the development and performance evaluation of a sensible thermal energy storage system that used sunflower oil and rock pebbles as heat storage mediums. The aim was to assess the system's performance based on charge and discharge rates, energy storage capacity, power output, cooking efficiency, and cost-effectiveness. The main body of the system was created with an old hot water geyser. An Arduino-based data logger was fabricated and was used to monitor and capture temperature changes throughout system operation periods. The data was analyzed with Python programming, from which time-temperature graphs were drawn. The heat retention capacity was obtained by heating the system to about 200 °C and then cooling it, with the time taken to cool being recorded. The system took approximately 30 hours to cool from 194℃ to 60℃. The system generated 0.028 kW of power and stored a total of 0.85 𝑘𝑊ℎ of heat energy. The efficiency testing, which involved boiling five liters of water, yielded an average efficiency of 78.98%. The total cost of constructing the system was: N$ 3,860, with a unit energy cost of N$ 1.26/kJ and a unit power cost of N$ 137.86/W. The cooking test demonstrated that the system could simultaneously cook 300 g of rice in 43 minutes and 300 g of dry beans in about 4 hours using only the stored thermal energy. The study therefore concluded that the developed system was able to deliver a reliable and cost effective solution for domestic use. Nonetheless, constraints including insufficient funding for further development and a limited timescale, impeded comprehensive investigation of the system's capabilities. Future research needs to improve the design of the system as well as explore the possibility of using solar PV panels to heat the TES system en University of Namibia Thermal energy storage Oil/rock bed Solar cooking Solar energy Heat energy Arduino data logger Namibia University of Namibia Design and performance evaluation of an oil/rock bed heat storage system for solar cooking Thesisopen.access