A　fin-and-tube　evaporator　can　be　used　for　an　ORC　(organic　Rankine　cycle)　to　collect　waste　heat　of　the　exhaust　gas　of　an　internal　combustion　engine.　In　this　paper,　the　thermal-hydraulic　characteristics　of　an　ORC　evaporator　are　analyzed　using　a　CFD　method.　A　3D　numerical　model　is　derived　from　an　engineering　diagram　of　the　fin-and-tube　evaporator,　and　the　boundary　conditions　are　specified　according　to　the　measured　data　obtained　by　the　engine　test.　The　simulation　results　show　that　the　exhaust　on　the　shell　side　flows　primarily　parallel　with　the　fin　layers.　Alternating　high　and　low　temperatures　appear　on　the　middle　planes　of　the　adjacent　tube　rows.　The　shapes　of　the　front-end　and　the　rear-end　parts　connecting　the　main　body　to　the　exhaust　pipes　are　important　factors　on　the　flow　field.　The　maximum　exhaust　pressure　decrease　in　the　fin-and-tube　evaporator　is　significantly　less　than　the　backpressure　limit　required　by　the　engine　exhaust　pipe.　The　simulation　results　are　verified　by　an　engine　experiment,　and　there　exists　a　correlation　between　the　numerical　results　and　the　actual　heat　transfer　process.　(C)　2015　Elsevier　Ltd.　All　rights　reserved.