Thermal　energy　storage　technology　has　attracted　extensive　attentions　due　to　its　remarkable　energy-saving　benefits.　However,　the　low　thermal　conductivity　of　phase　change　materials　seriously　limits　the　energy　storage　efficiency,　which　put　forward　more　stringent　requirements　for　heat　transfer　enhancement.　In　this　study,　a　two-dimensional　axisymmetric　simulation　model　with　natural　convection　was　established　for　the　shell-and-tube　thermal　energy　storage　unit.　Open-cell　metal　foam　with　a　porosity　of　0.94　and　pore　density　of　15　pore　per　inch　was　employed　to　be　arranged　in　either　heat　transfer　fluid　or　phase　change　materials　domains.　The　effects　of　the　metal　foam　location　and　the　metal　foam　porosity　on　the　heat　storage　performance　were　studied.　The　numerical　method　was　verified　by　experimental　measurement,　achieving　good　agreement.　Results　demonstrated　that　metal　foam　can　significantly　enhance　heat　transfer　due　mainly　to　the　reduction　of　thermal　resistance　in　heat　transfer　fluid.　The　case　that　both　domains　for　heat　transfer　fluid　and　phase　change　materials　were　embedded　in　porous　media　can　provide　the　best　heat　transfer　enhancement.　Compared　with　smooth　tube　without　metal　foam,　the　full　melting　time　for　this　case　was　reduced　by　88.548%;　meanwhile,　temperature　response　rate,　heat　flux　and　j-factor　was　increased　by　834.27%,　774.90%,　5186.91%　respectively.　Besides,　embedding　metal　foam　into　phase　change　materials　can　improve　the　temperature　uniformity　of　phase　change　materials.