A　new　ice-storage　experimental　system　with　a　closed　(CIST)　and　an　open　(OIST)　ice-storage　tank　has　been　exploited,　with　which　the　external　ice　melting　processes　are　studied　experimentally.　Furthermore,　the　researches　on　combinations　of　external　and　internal　ice　melting　have　been　carried　out.　The　experiments　indicate　that　the　cold　release　rate　of　CIST　is　more　stable　than　that　of　OIST　under　the　same　conditions,　especially,　the　cold　release　rate　of　OIST　decreases　significantly　at　the　later　stage　of　the　discharging　process.　The　outlet　temperature　of　the　discharge　water　flowing　from　the　bottom-to-top　(Mode　1)　is　lower　than　that　from　the　top-to-bottom　of　the　ice-storage　tank　(Mode　2).　With　the　relatively　lower　volumetric-flow　rate,　the　outlet　temperatures　of　the　discharge　water　rise　slowly,　meanwhile,　the　cold　release　rate　is　also　relatively　lower.　To　solve　the　problem　of　＂millennial　ice＂　in　the　external　system　without　an　air-agitation　device,　two　types　of　the　combination　of　external　and　internal　ice　melting　have　been　adopted,　one　is　to　adopt　internal　ice　melting　at　first,　and　then　external　ice　melting,　the　other　is　to　adopt　simultaneously　the　internal　and　external　ice　melting.　The　experiments　show　that　the　cumulative　discharging　capacity　of　the　latter　has　been　significantly　improved.　(C)　2019　Elsevier　B.V.　All　rights　reserved.