Study on temperature and updraft velocity in a solar chimney with steel spheres for heat energy storage

The most abundant solar energy can be considered as a big asset for dry and semi-dry regions. In the recent years, solar chimney which is a solar thermal energy driven electrical power generation plant that converts the solar thermal energy into electrical power are in use. In this work, the performance of the scaled model of solar chimney is studied with the usage of steel spheres filled with water as heat energy storage material. Initially the solar radiation intensity was measured with KDS-051 Global Radiation Sensor. The placements of the spheres were carried out in three different configurations with a fixed pattern and suitable distance of 30–35 cm between each sphere so that good results in term of temperature retained in collector is achieved. The configurations were 50%,60% and 70% of collector area respectively. The temperature data were collected using a ‘J’ type thermocouple at various sections of the solar chimney for a period of two months during sunny, cloudy and partly cloudy days. The temperature and updraft velocities of solar chimney was also monitored for overcast weather conditions. The results show that there is no rapid decrease in collector temperature during evening time due to the presence of steel spheres. Due to the larger surface area of steel spheres i.e. 70% coverage of collector area with heat energy storage material, the temperature of the collector was maintained upto 65 °C during evening time.