Among　household　refrigerators,　air　cooled　frost-free　household　refrigerators　have　become　popular　in　the　market　because　of　the　advantages　of　large　storage　volume　and　frost-free　compartment(s).　However,　the　large　power　consumed　by　the　process　of　defrosting　the　evaporator　restricts　the　widespread　application　of　such　refrigerators.　In　this　study,　a　new　type　of　thermal　storage　defrosting　system　combined　with　bypass　cycle　is　presented,　the　feasibility　of　the　thermal　storage　defrosting　system　is　analyzed,　four　kinds　of　different　PCMs　are　tested,　the　operation　modes　of　the　overall　system　are　proposed,　and　the　structure　of　the　heat　storage　exchangers　is　designed　and　optimized.　Next,　the　experimental　prototype　is　set　up,　and　the　experimental　study　is　carried　out　for　different　defrosting　modes.　The　results　show　that　the　best　defrosting　mode　enhances　the　defrosting　speed　by　about　50%　more　than　the　original　electric　heating　model　as　well　as　reduces　defrosting　electric　power　consumption　by　about　71%.　(C)　2017　Elsevier　Ltd.　All　rights　reserved.