Previous　studies　obtained　the　heat　and　mass　transfer　coefficients　of　Indirect　evaporative　coolers　(IECs)　with　condensation　based　on　the　following　assumptions:　(1)　empirical　equations　in　the　dry　channel　without　water　evaporation　or　condensation,　or　the　boundary　condition　is　assumed　to　be　a　constant　surface　heat　flux　or　temperature　so　that　constant　values　of　Nusselt　number　can　be　employed　for　evaluating　the　heat　transfer　coefficient;　and　(2)　Lewis　number　is　assumed　to　be　unity　so　that　the　mass　transfer　coefficients　can　be　then　calculated　via　the　heat　and　mass　transfer　analogy.　Thus　far,　the　heat　and　mass　transfer　coefficients　of　IECs　with　condensation　under　naturally　formed　boundary　condition　are　lacking.　In　this　paper,　an　experimental-validated　computational　fluid　dynamics　(CFD)　model　has　been　established　to　investigate　the　heat　and　mass　transfer　processes　of　IECs　incorporating　the　phenomenon　of　condensation.　A　single　factor　analysis　and　a　multiple　factor　analysis　are　concurrently　carried　out　to　evaluate　the　effects　of　the　nine　parameters　on　the　heat　and　mass　transfer　processes　of　IECs.　Key　findings　revealed　that　both　mean　Nusselt　and　Sherwood　numbers　under　the　presented　conditions　are　larger　than　those　obtained　under　constant　surface　temperature　and　heat　flux　conditions;　and　the　respective　values　of　the　primary　and　secondary　Lewis　numbers　are　observed　to　change　from　0.37　to　0.75　and　0.70　to　0.85　which　severely　deviate　from　the　conventional　assumed　value　of　unity.　Finally,　empirical　correlations　are　developed　for　the　mean　heat　and　mass　transfer　coefficients　based　on　an　orthogonal　test　method.　The　simplified　linear　correlations　can　serve　as　new　fundamental　references　to　account　for　IEC　that　are　consistently　experiencing　with　condensation.　©　2020　Elsevier　Ltd