Design of Molten Salt Thermal Storage Tank

Malaysia is located near the equator. Therefore, it receives equal hours of day and night.
Malaysia also receives sunshine throughout the year. However it is not continuous.
There are days where there is less sunlight due to rain, windy days, monsoon season and
etc. The amount of sunlight days in Malaysia is about 60-70% in a year. The amount of
solar irradiations receive by Malaysia is approximately 400 to 800 W/m2. The sunshine
during daylight provides us with great quantity of thermal energy. Therefore, solar
thermal energy available throughout the day is important to be used for the night time
and other sunless days. This paper is prepared to design a Molten Salt Thermal Storage
Tank to store an amount of thermal energy for the night usage. This design is conducted
based on the weather data obtained throughout year 2008 in Ipoh, Malaysia. The
following objectives are to be met for the design of Salt Thermal Storage Tank:
1. To calculate the available amount of solar energy during the day time.
2. Select a suitable media (molten salt) to store thermal energy.
3. To design an underground thermal energy storage to store the excess energy
during the daytime.
Designing a storage tank is to conserve the thermal energy that is produced by the sun
during the day and use the stored thermal energy to be converted to electricity using
turbines. This report includes the selection of material and the design of the thermal
storage tank. Research and analysis have been done to determine the available solar
radiations which will be used to calculate the available amount of heat energy that can
be stored daily. The design of the Molten Salt Thermal Storage Tank is designed based
on the calculations done using the available weather data. The results show the daily
available power in Ipoh would be 3000Whr/m2. This includes approximately 6 hours of
sunshine daily. For this design, Sodium Nitrate (NaNO3) is used as the heat transfer
fluid. An insulated storage tank of volume 1.8 m3 containing 0.85 m3 of NaNO3 is placed
underground to reduce the heat loss. The amount of energy stored in the storage tank is
20 MJ daily.