It　is　important　to　cool　data　centers　for　improving　IT　equipment　reliability　through　indoor　temperature　control.　The　air　conditioning　energy　consumption　is　almost　38%　of　the　total　energy　consumption.　Free　cooling　in　cool　days　is　a　promising　technology　for　energy　conservation.　A　pump-driven　loop　heat　pipe　(PLHP)　system　for　free　cooling　was　developed　and　installed　in　a　data　center　project,　which　has　a　high　energy　efficiency　ratio　(EER)　compared　to　air　conditioners.　The　running　performance　of　the　PLHP　system　in　the　case　project　was　tested　and　studied.　The　fitting　rule　of　EER　and　outdoor　temperature　was　obtained.　The　hourly　energy　savings　and　payback　periods　of　the　PLHP　system　for　different　cities　of　different　climate　regions　in　China　were　analyzed　basing　on　the　fitting　formula　compared　to　air　conditioners.　A　national　distribution　map　was　developed　to　show　the　annual　energy　saving　ratio　in　China.　Results　show　that　the　PLHP　system　provides　remarkable　energy　savings　and　the　indoor　temperature　is　remained　at　18　degrees　C　to　25　degrees　C.　About　74.2%　of　Chinese　cities　lie　in　regions　suitable　for　applications,　and　the　annual　energy　saving　ratio　is　over　30%.　The　average　payback　period　for　most　cities　in　China　is　about　3.9　years.　(C)　2018　Elsevier　B.V.　All　rights　reserved.