To　further　improve　the　flat-type　loop　heat　pipe　(LHP)　performance,　this　study　evaluates　the　practical　potential　of　use　of　highly　enhanced　boiling　structures.　It　is　found　that　in　our　proposed　new　heat　pipe　(NHP)　system,　the　working　fluid　from　the　evaporator　outlet　to　the　condenser　inlet　is　in　a　liquid-vapor　two　phase　flow,　which　is　different　from　the　classical　LHP　theory.　A　new　P-T　diagram　is　developed　to　better　understand　the　thermal　and　hydraulic　process　during　the　NHP　steady　operation.　In　this　study,　by　using　the　laser　ablation　technique　two　different　types　of　micro-　and　nanoscale　hybrid　structures　are　synthesized　on　the　boiling　pool　substrate.　It　is　indicated　that　the　formed　valleys　with　a　larger　opening　width　play　an　important　role　in　more　effectively　improving　the　bubble　nucleation　and　bubble　growth　at　the　micrometer　sites,　which　can　subsequently　lead　to　an　increased　number　of　active　nucleation　sites.　The　best　loop　performance　is　obtained　with　the　micro-cone　structured　substrate　at　a　heat　load　of　140　W,　at　which　the　maximum　boiling　pool　heat　transfer　coefficient　of　42.17　kW/m(2).K　is　achieved.　Compared　with　the　polishing　Cu　substrate,　it　is　enhanced　by　110%.　When　maintaining　the　boiling　pool　temperature　lower　than　85　degrees　C,　the　proposed　new　heat　pipe　system　can　tolerate　a　maximum　heat　flux　of　35.12　W/cm(2),　which　is　larger　than　that　of　the　most　conventional　LHPs　with　methanol　as　the　working　fluid.　(C)　2018　Elsevier　Ltd.　All　rights　reserved.