In　this　study,　the　nonisothermal　two-phase　heat　transfer　in　the　rectangular　helical　channel　is　proposed　to　effectively　reduce　the　heat　transfer　losses　in　the　single　screw　expander.　The　interphase　heat　transfer　rate　and　temperature　distribution　of　the　nonisothermal　gas-liquid　two-phase　flow　in　the　rectangular　helical　channel　are　experimentally　investigated　under　different　gas-liquid　flow　rates,　gas　phase　temperatures,　and　dimensionless　pitch　and　curvature.　The　results　indicate　that　increasing　Rel　and　Reg　will　enhance　the　interphase　heat　transfer　rate,　and　the　effect　of　Rel　on　the　heat　transfer　rate　is　gradually　weakened　at　a　larger　Re.　A　further　increase　in　Reg　obviously　increases　the　interphase　heat　transfer　rate,　but　it　has　little　influence　on　the　peak　temperature　and　temperature　distribution　of　the　gas.　The　interphase　heat　transfer　rate　is　much　higher　for　the　helical　channel　with　γ　=　0.145.　A　maximum　reduction　of　28.5　J/s　in　the　interphase　heat　transfer　rate　is　obtained　by　decreasing　the　curvature　ratio　of　the　helical　channel　from　0.145　to　0.129.　Furthermore,　a　maximum　reduction　of　36.5　J/s　in　the　interphase　heat　transfer　rate　is　obtained　by　decreasing　the　dimensionless　pitch　of　helical　channel　from　0.9　to　0.5.　©　2024　Elsevier　Inc.