Engine　exhaust　can　be　used　by　thermoelectric　generators　for　improving　thermal　efficiency　of　internal　combustion　engines.　In　his　paper,　the　performance　of　a　thermoelectric　evaporation　system　is　investigated.　First,　the　thermal　characteristics　of　diesel　engines　are　obtained　according　to　the　experiment　data.　Then,　mathematical　models　are　created　based　on　the　specified　conditions　of　the　coolant　cycle　and　the　evaporator　geometric　parameters.　Finally,　the　heat　transfer　characteristics　and　power　performance　of　the　thermoelectric　evaporation　system　are　estimated,　and　a　comparison　with　the　system　in　which　the　heat　exchanger　operates　with　all-liquid　coolant　is　investigated.　The　results　show　that　the　overall　heat　transfer　rate　of　the　thermoelectric　evaporator　system　increases　with　engine　power.　At　the　rated　condition,　the　two-phase　zone　with　an　area　of　0.8689　m(2)　dominates　the　evaporator＇s　heat　transfer　area　compared　with　the　preheated　zone　area　of　0.0055　m(2),　and　for　the　thermoelectric　module,　the　cold-side　temperature　is　stable　at　74　degrees　C　while　the　hot-side　temperature　drops　from　341.8　degrees　C　to　304.9　degrees　C　along　the　exhaust　direction.　For　certain　thermoelectric　cells,　the　temperature　difference　between　the　cold　side　and　hot　side　rises　with　the　engine　load,　and　the　temperature　difference　drops　from　266.9　degrees　C　to　230.6　degrees　C　along　the　exhaust　direction.　For　two　cold-side　systems　with　the　same　heat　transfer,　coolant　mass　flow　rate　in　the　evaporator　with　two-phase　state　is　much　less,　and　the　temperature　difference　along　with　equivalent　heat　transfer　length　L　is　significantly　larger　than　in　the　all-liquid　one.　At　rated　power　point,　power　generated　by　thermoelectric　cells　in　the　two-phase　evaporation　system　is　508.4　W,　while　the　other　is　only　328.8　W.