Abstract: A supercharged internal combustion engine (1), such as a main engine of a ship, has a compressor (9) delivering charging and scavenging air to the engine cylinders, and a cooler (12) for cooling the air from the compressor. The cooler (12) is designed to establish direct contact between the scavenging and charging air and the cooling water, preferably by pressure atomization of the water in the air. The cooler (12) has a number of consecutive atomizer sections, and a drop collecting section (33) separating drops of water from the air may be provided between at least two atomizer sections. A delivery pump (49) supplies fresh water to atomizer sections in the cooler, and at least one of the drop collecting sections of the cooler delivers fresh water to a storage tank (50), which tank is pressured to substantially the same pressure as the air pressure in the cooler. The air may be cooled in plural stages (13-16), and sea water may be used for cooling and humidification of the air in the first stage.

Abstract: Exhaust gas in a supercharged internal combustion engine is recycled from the high pressure side of the turbocharger to the charging air system of the engine. At least part of the recycled exhaust gas is humidified to largely 100 percent relative humidity. This on one hand cools the gas to that the temperature at initiation of the combustion in the engine cylinders is lowered, and on the other hand the heat capacity of the steam in the gas restricts the temperature raise occurring during the combustion. These factors both act to reduce the amount of NO.sub.x produced by the combustion. The addition of water is effected by a scrubber (16) which purifies the recycled gas. A blower (17) augments the pressure of the recycled gas. The scrubber may be made to generate fresh water by designing it with several stages where sea water is supplied to the first stage and fresh water to the last stage.