Purpose of Charge Air Cooler?

The exhaust gas from the engine is utilized in the turbocharger for compressing fresh air to charge the engine with a positive pressure greater than ambient conditions. This compression causes the temperature of the air to increase, which thus cannot be fed directly into the engine as it is out of operating limits. Thus a cooler that brings the air temperature back to near ambient conditions is fitted on the engine. When the air is hot its density is less and thus the mass of air charged into the engine is less when compared to the mass when the air is cold. Thus the charge air cooler improves the charge air density and its temperature.

The compressed charged air at the outlet of charged air cooler will have a reduced temperature of about 40 to 50 degrees celsius from a temperature of about 200 degrees celsius. This reduced temperature of the air will increase the density of the charge ait at low temperatures. Increased air density of the charge air will raise the scavenge efficiency and allow a greater mass of air to be compressed inside the engine cylinder so that more fuel can be burned inside the combustion chamber giving an increase in power. Also the engine is maintained at a safe working temperature. The lower compression temperature reduces stress on the piston, piston ring, cylinder liner, and cylinder head. The charge air cooler has another advantage in that it reduces the exhaust temperature. It has been proven that every one-degree Celsius drop in scavenging air temperature will reduce the exhaust temperature about 5 to 10 degrees celsius. This does not mean that the air can be charged at cryogenic temperatures. IF very cold air enters the cylinder liner it could cause thermal shock leading to cracking of liner.

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Difference Between A, B & C-Class Divisions?

IMO Symbol A Class Division IMO Symbol B Class Division SOLAS has tables for structural fire protection requirement of bulkheads and decks. The requirements depend on the spaces in question and are different for passenger ships and cargo ships. The Administration has required a test of a prototype bulkhead or deck in accordance with the Fire Test Procedures Code to ensure that it meets the above requirements for integrity and temperature rise. Types of Divisions: "A" Class "B" Class "C" Class "A" Class: "A" class divisions are those divisions formed by bulkheads and decks which comply with the following criteria: They are constructed of steel or equivalent material They are suitably stiffened They are constructed as to be capable of preventing the passage of smoke and flame to the end of the one-hour standard fire test. they are insulated with approved non-combustible materials such that the average tempera

Why do we blow through engine before starting ?

The engine is blown through on air before starting it : a) To Blow out through indicator cock any residual exhaust gas or other products of combustion trapped inside the cylinder after shutting the engine. b) To check if any jacket cooling water from cylinder head or turbocharger or any other source, has leaked while the engine was shut and collected on top of piston. If while blowing through, water comes out of indicator cock or relief valve, we need to investigate and rectify the fault before starting the engine. It is imperative that the engine is blown through before starting. There have been cases where the generator engine has been started from control room without bothering to blow through first, and water collected on top of piston has resulted in a bent connecting rod and broken piston.( Reason – water can not be compressed )

Load Line & Why it is Important

Merchant ships have a marking on their hull know as the Plimsoll line or the Plimsoll mark, which indicates the limit until which ships can be loaded with enough cargo, internationally, the Plimsoll line on a ship is officially referred to as the international load line. Every type of ship has a different level of floating and the Plimsoll line on a ship generally varies from one vessel to another. All vessels of 24 meters and more are required to have this Load line marking at the centre position of the length of summer load water line. There are two types of Load line markings:- Standard Load Line marking – This is applicable to all types of vessels. Timber Load Line Markings – This is applicable to vessels carrying timber cargo. These marks shall be punched on the surface of the hull making it visible even if the ship side paint fades out. The marks shall again be painted with white or yellow colour on a dark background/black on a light background. The comp

Marine Engineering

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