An　organic　Rankine　cycle　(ORC)　can　be　applied　to　recover　the　low-grade　waste　heat.　In　this　paper,　the　performances　of　five　different　types　of　ORC　are　evaluated.　These　configurations　include　a　simple　ORC,　an　ORC　with　an　internal　heat　exchanger　(IHE),　an　ORC　with　an　open　feed　organic　fluid　heater　(OFOH),　an　ORC　with　a　closed　feed　organic　fluid　heater　(CFOH),　and　an　ORC　with　a　reheater.　First,　the　feasible　working　region　is　defined　for　an　ORC　operating　together　with　an　internal　combustion　engine.　Subsequently,　the　thermal　efficiency　of　each　ORC　is　maximized　using　a　genetic　algorithm.　Finally,　the　characteristics　of　each　ORC　are　analyzed　and　compared　using　a　combination　of　the　first　law　and　second　law　method.　Our　analysis　indicates　that　the　ORC　with　an　IHE　showed　the　best　thermodynamic　performance.　The　ORC　with　an　OFOH　and　the　ORC　with　a　CFOH　are　sub-optimal　while　the　simple　ORC　and　the　ORC　with　a　reheater　are　the　last　choice.　The　effects　of　the　expander　inlet　pressure,　the　condenser　outlet　temperature　and　the　expander　isentropic　efficiency　on　system　performance　of　each　ORC　were　also　analyzed.