The study aims to improve the waste thermal energy retrieval from flue gas of an internal combustion engine (ICE). The recovered waste heat energy was used for distillation by using a thermal distillation system. The performance of the thermal distillation unit was investigated by varying the evaporator (boiler) type and engine load (25, 50, 75 %). Four different types of boilers were used including one smooth copper tube and other three were two, three and four axial finned copper tube evaporators. The impact of boiler type and engine load on the net retrieved energy and exergy, net energy and exergy efficiency, and distillate yield rate of thermal distillation unit was also examined. The results showed that the net extracted heat energy and exergy for axial finned tube evaporator was approximately 26.823 – 45.513 % and 7.614 – 25.203 W higher than that of smooth tubes evaporator at 25 and 75 % engine load, respectively. The distillation yield was found to be ~ 2.35 liter/ hour in the case of four axial finned tube boiler at 75 % engine load.