Internal-combustion engines – Charge forming device – Supercharger
Patent
1995-12-04
1998-09-22
Koczo, Michael
Internal-combustion engines
Charge forming device
Supercharger
552573, 123 25G, F02B 2904
Patent
active
058099816
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a large supercharged internal combustion engine, such as a main engine of a ship, having a compressor delivering charging and scavenging air to the engine cylinders, and a cooler for cooling the air from the compressor.
The compression of the intake air in the compressor causes the air temperature to rise. The air is cooled in the cooler before delivery to the cylinders to enable these to be filled with a sufficiently large amount of air for the combustion process to proceed with the desired excess of air.
British patent No. 1 496 548 describes a small diesel engine wherein the intake air passes through a venturi nozzle disposed between a compressor and the engine cylinders. The venturi nozzle sucks up water from a water tank so that the air is cooled by evaporation of the water. The patent states that the cooling method is applicable in engines having an output of less than 150 hp, i.e., very small diesel engines. The cooling obtainable by evaporation is relatively limited and quite insufficient in large diesel engines where the achievement of the best possible combustion conditions is of great importance to the achievement of a good operating economy. The water content of saturated air rises very steeply in step with an increasing air temperature. As a result of the fact that the air temperature after the evaporation cooling is still relatively high, the air contains large amounts of water at the inlet to the combustion chambers, which has a negative effect on the combustion and results in a very large water consumption which would reach quite unacceptable levels in large engines.
For many years, in large two-stroke diesel engines, the cooler has been designed as a pipe fin cooler, in which the cooling water flows through the pipes and the air is directed past closely spaced fins mounted on the outside of the pipes. The use of a pipe fin cooler has conventionally been justified by the facts that the cooler has a large surface area on the air side, and that this type of cooler is able to carry away the very large amounts of heat formed by compression of the intake air in large two-stroke engine to a pressure of more than 3 bar, for example.
The pipe fin coolers require significant maintenance, partly because the fins catch impurities from the air, partly because the cooler uses sea water resulting in depositions and oxide formation on the inside of the pipes, partly because the water has a corrosive effect on the pipes, especially if the cooling water contains pollutants, such as sulphur sulphide and ammonia, which have a strongly erosive effect on copper alloys. The depositions on pipes and fins have an insulating effect and consequently hamper the cooling of the air. Thus, at regular intervals, it is necessary to clean the cooler for depositions and check its condition, which requires work and is costly. As a result of the corrosive erosion of pipes and fins, the pipe fin cooler has a substantially shorter life than the engine and normally has to be replaced during the life of the engine. These disadvantages have been accepted for a large number of years by shipowners and at stationary power plants where large internal combustion engines are used to drive generators.
The object of the invention is to provide a cooler for the intake system of a large engine, which cooler has a large cooling capacity, functions efficiently and is operationally reliable, and only requires slight maintenance.
In view of this object, the engine according to the invention is characterized in that the cooler is designed to establish direct contact between the scavenging and charging air and the cooling water by pressure atomization of the water in the air, that the cooler has a number of consecutive atomizer sections, and that a drop collecting section separating drops of water from the air is provided between at least two atomizer sections.
The cooler as a whole has no major water consumption despite the cooling being effected by means of pressure atomization of water. This is due to the fact that aft
REFERENCES:
patent: 1594616 (1926-08-01), Heffernan
patent: 1854607 (1932-04-01), Andrews
patent: 1890107 (1932-12-01), Bowman
patent: 2258088 (1941-10-01), Dunn
patent: 3922153 (1975-11-01), Engalitcheff, Jr. et al.
Derwent's abstract, No. 85-170356/28, week 8528, Abstract of SU, A, 1132043(Mosc Region Tractor), Dec. 30, 1984.
Koczo Michael
Man B&W Diesel A/S
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