Although　Janus　membranes　have　shown　excellent　anti-wetting　and　fouling-resistant　properties　in　membrane　distillation　(MD),　the　associated　heat　and　mass　transfer　mechanisms　remain　insufficiently　understood,　particularly　concerning　the　trade-off　between　fouling　resistance　and　permeate　flux.　In　this　study,　a　Janus　membrane　was　fabricated　by　depositing　a　polyamide　(PA)　layer　onto　a　polyvinylidene　fluoride　(PVDF)　substrate　to　form　a　PA/PVDF　composite.　To　elucidate　the　mass　transfer　behavior,　an　enhanced　computational　fluid　dynamics　(CFD)　model,　considering　the　effects　of　membrane　material　and　surface　temperature　on　evaporation　enthalpy,　was　developed　to　simulate　MD　performance　using　both　PA/PVDF　and　pristine　PVDF　membranes.　When　assuming　a　constant　evaporation　enthalpy　of　free　water　(FW)　(2.44　MJ·kg−1),　the　modeled　and　experimental　fluxes　matched　closely　for　the　PVDF　membrane,　while　a　flux　deviation　exceeding　10　%　was　observed　for　the　PA/PVDF　membrane.　Accounting　for　the　membrane-specific　evaporation　enthalpy　reduced　the　deviation　to　0.59　%,　emphasizing　its　critical　role　in　flux　prediction.　These　results　highlight　the　importance　of　incorporating　membrane-dependent　thermodynamic　properties　to　improve　MD　modeling　accuracy　and　guide　the　rational　design　of　Janus　membranes.　©　2025　Elsevier　B.V.