Three-dimensional　external　finned　tube　heat　exchanger　has　been　widely　applied　in　waste　heat　recovery　system.　However,　the　current　researches　mainly　focus　on　its　fluid　flow　and　heat　transfer　characteristics.　The　condensation　of　sulfuric　acid　and　water　vapors　on　heat　exchanger　surface,　which　can　cause　severe　low　temperature　corrosion　and　reduce　equipment　efficiency,　has　rarely　been　reported.　In　this　study,　a　heat　and　mass　transfer　model　for　flue　gas　on　finned　tube　surface　was　developed　to　investigate　the　sulfuric　acid　and　water　vapor　condensation　characteristics　and　their　distributions.　The　effects　of　flue　gas　velocity　and　temperature,　acid　and　water　vapor　concentrations,　and　surface　temperature　were　examined.　The　results　show　that　the　distribution　of　acid　solution　concentration　on　finned　tube　surface　mostly　depends　on　the　distribution　of　fin　surface　temperature.　At　the　windward　side　(especially　near　the　minimum　flow　cross　section　region),　both　fin　surface　temperature　and　condensed　acid　solution　concentration　reaches　the　maximum　value.　Increasing　velocity　leads　to　vapors　condensation　rate　and　acid　solution　concentration　increasing.　The　acid　solution　concentration　decreases　with　flue　gas　temperature　or　tube　wall　temperature　increasing.　The　present　work　could　provide　effective　theoretical　guidance　for　anti-corrosion　design　of　finned　tube　heat　exchanger.　©　2019　Elsevier　Ltd