In　this　study,　a　compact　ice　thermal　storage　device　that　combines　multichannel　flat　tube　and　closed　rectangular　fins　is　designed　to　improve　solidification　performance.　To　analyze　the　heat　transfer　characteristics　and　visualize　the　ice　formation　process,　a　numerical　model　was　formulated　and　solved　using　enthalpyporosity　method.　The　temperature　distribution,　liquid　fraction,　and　ice　front　evolution　were　studied　during　solidification　process.　The　effect　of　heat　transfer　fluid　on　the　performance　of　storage　device　at　different　inlet　temperatures　and　flow　rates　was　numerically　investigated.　Results　show　that　when　the　inlet　temperature　was　reduced　from　-3　degrees　C　to　-6　degrees　C,　the　ice　packing　factor　increased　by　32.2%　and　the　storage　power　forms　a　linear　relationship　with　the　inlet　temperature.　When　the　flow　rate　was　increased　from　0.1　m(3)/h　to　0.2　m(3)/h,　the　ice　packing　factor　increased　by　8.7%　but　the　effect　of　flow　rate　was　less　obvious　than　the　inlet　temperature.　Furthermore,　the　heat　transfer　characteristics　of　closed　rectangular　fins　were　compared　with　traditional　longitudinal　fins.　We　found　that　the　former　can　achieve　more　uniform　temperature　distribution　and　a　higher　ice　formation　rate.　The　average　solidification　enhancement　ratios　of　the　both　are　2.28　and　2.08,　respectively,　the　former　being　9.6%　higher　than　the　latter.　(C)　2021　Elsevier　Ltd.　All　rights　reserved.