Heat　transfer　in　molten　salt　in　a　cylinder　tank　is　studied　via　simulation　and　experiment　to　obtain　its　natural　convection　heat　transfer　in　a　single　energy　storage　tank.　Simulation　and　experimental　results　show　that　the　natural　convection　heat　transfer　of　water　in　a　cylinder　tank　fits　well　with　Garon＇s　correlation.　However,　significant　deviations　occur　when　Garon＇s　correlation　is　used　to　predict　the　natural　convection　heat　transfer　of　molten　salt　because　of　its　high　viscosity　and　low　thermal　conductivity.　However,　the　simulated　data　of　the　natural　convection　heat　transfer　of　molten　salt　fit　well　with　those　of　the　experimental　results.　Thus,　a　correlation　that　considers　the　effect　of　variable　physical　properties　is　proposed　in　this　study　to　predict　the　natural　convection　heat　transfer　of　molten　salt.　The　deviation　of　the　present　data　from　the　proposed　correlation　is　less　than　+/-　20%.　The　results　of　this　study　can　serve　as　a　basis　for　the　design　of　single　energy　storage　tanks.