There is usually a minimum temperature recommended by the engine manufacturer for sea water used as a secondary coolant. Which of the following methods is the most common used to achieve this minimum temperature?

• Partial recirculation of the sea water

• Mixing steam with the seawater

• Reduction of flow of the seawater

• Preheating the seawater using electric heaters

The use of air cooling for large engines is normally limited due to which of the following?

• Limited availability

• High potential to form scale  on the heat transfer surfaces

• Low specific heat capacity  an density

• High cost

   Choose from the options given bellow the one which correctly completes the following statement -Diesel engines need to be cooled in order to…..

• minimize scale formation

• maintain component clearances and material properties

• maximize engine efficiency

• Minimize soot deposits   

Which of the following values would be a typical or the specific heat capacity of the mineral oil?

• 4.0 kJ

• 2.0 kJ

•   4.2 kJ/kgK

• 2.0 kJ/kgK

Which of the following option is the reason of diesel engine components heating up during normal operation?

• Heat transferred from the engine room

• Heat transferred from the jacket cooling water

• Heat transferred from circulation o lubrication oil

• Heat released during combustion and generated from friction

   

Which of the following options is the main purpose of a jacket cooling water system of a diesel engine?

• To cool the turbocharger and exhaust valve cages

• To maintain the temperature of the cylinder liner and cylinder cover within recommended limits

• To cool the engine lubricating oil

•   To allow preheating of the engine

Modern engine designs usually incorporate oil cooling of the pistons. Which of the following options is the main reason for this?

• To reduce fouling of the cooling spaces

• To help preheat the engine

• To eliminate the risk of water contamination of the crankcase

• Oil has a high specific capacity

When discussing diesel engine cooling water system the term “cocktail shaker effect” refers to cooling mechanism for which of the following?

• Fuel injection valves

• Piston

• Cylinder liner

• Turbocharger

Jacket cooling water is sometimes used as the heating source for the fresh water generator. The main reason for this is to…

• Minimize the amount of sea water required as secondary coolant

• Prevent fouling of fresh water generator heat exchanger

• Recover waste heat to improve overall plan efficiency

• Reduce the size of jacket water cooler

What is the main reason for using central cooling systems on board?

• to allow plate heat exchangers to be used

• to minimize the amount of sea water pipework and so minimize maintains requirements

• to allow fresh water generator to be heated

• to avoid the need for seawater pipe work