CFD Simulation of Portable Thermal Storage Device for Solar Cooking System

Energy consumption for cooking is significantly high around the world including in India. In rural India, the fuels used for cooking are mainly loose biomass, wood, and dung cake which is burned in traditional cookstoves. The poor combustion efficiency of traditional cookstoves leads to larger fuels requirement and indoor pollution, which eventually leads to chronic disease among women. A solar cooker is one of the environment-friendly technology and runs on renewable energy. However, existing designs suffer from the issues like a limitation to use outdoors, continuous attention while use and only sunny hours of operation. Such issues make it unpopular among the masses and hinder its proliferation in the market. This problem can be solved by storing solar energy as heat at the desired temperature. Furthermore, if there is a mismatch between thermal energy supply and use, thermal energy storage (TES) is crucial in a phase change material (PCM) due to its high heat storage capacity and short temperature swing. In this paper, the simulation of the portable solar thermal energy storage device has been studied. To store the thermal energy, sodium nitrate has been selected as a PCM. Here, the grid independence and time independence test has been done to optimize the grid size and time step. A constant temperature boundary condition (773 K) at the top wall has been given for the charging of the device and the rest walls are assumed to be perfectly insulators. Discharging of the PCM has been done at a constant temperature of 553 K at a top wall and the rest walls are assumed to be perfectly insulated. The total time required for complete charging and discharging of the TES device is 6.3 h and 9.53 h respectively.