Numerical Study of a High Temperature Latent Heat Storage (200-300oC) Using Eutectic Nitrate Salt of Sodium Nitrate and Potassium Nitrate

C.W. Foong, J.E. Hustad, J. Løvseth, and O.J. Nydal
Department of Energy and Process Engineering, Norwegian University of Science and Technology, Trondheim, Norway

In this study, a small scale direct solar thermal energy storage system with secondary reflector is designed and developed. The main advantage of thermal energy storage is that cooking can be carried out during the time when there is little or no sun shine. In addition, no heat transport fluid is needed in this system. A well insulated heat storage should keep the heat for about 24 hours. KNO3 and NaNO3 in 60:40 percent ratio (mol %) is used as latent heat storage material. This type of salt is also used in large scale solar power plant to produce electricity. The PCM thermal heat storage with and without fin are numerically simulated using COMSOL Multiphysics. During melting of PCM, extra energy in the form of latent heat of fusion is needed. This effect is added into the phase change behavior simulation by modifying the specific heat capacity of PCM.