An　experimental　rig　was　set　up　to　study　the　performance　of　a　thermal　storage　unit　using　stearic　acid　as　the　heat　storage　medium.　The　unit　mainly　consists　of　an　electrical　heating　rod　and　an　outer　tube,　and　the　space　between　is　an　annulus　that　is　filled　with　stearic　acid.　The　thermal　performance　of　the　unit　is　measured,　and　the　heat　transfer　characteristics　of　the　melting　processes　of　stearic　acid　are　studied　under　different　heat　flux　conditions　to　determine　the　influence　of　heat　flux　on　the　melting　processes.　A　new　type　of　fin　is　designed　and　fixed　to　the　electrical　heating　rod　to　enhance　the　thermal　response　of　the　stearic　acid.　The　experimental　results　show　that　the　fin　can　improve　the　heat　transfer　of　the　melting　process　of　the　thermal　storage　unit　greatly.　The　equivalent　thermal　conductivity　of　the　PCM　can　be　augmented　by　a　factor　up　to　3.　The　analysis　of　the　experimental　results　shows　that　the　enhancement　mechanism　of　the　fin　is　attributed　to　its　ability　to　improve　both　heat　conduction　and　natural　convection　very　effectively.　The　influences　of　the　fin　size　and　pitch　on　the　enhancement　are　also　studied　and　analyzed　and　it　is　found　that　these　two　parameters　can　both　affect　the　thermal　conductivity　enhancement　significantly.　(C)　2004　Elsevier　Ltd.　All　rights　reserved.