THE COOLING PUMPS AND COOLING SYSTEMS
DEFINITION OF TERMS
Cooling System - equipment in a motor vehicle that cools the engine. Water Cooling is a method of heat removal from components and industrial equipment. As opposed to air cooling, water is used as the heat conductor. Water cooling is commonly used for cooling automobile internal combustion engines and large industrial facilities such as steam electric power plants, hydroelectric generators, petroleum refineries and chemical plants. Water Pump - the pump in the cooling system of an automobile that cause the water to circulate. Pump - a mechanical device that moves fluid or gas by pressure or suction
THE COOLING WATER PUMP
Although there is an abundance of free sea water available, marine diesel engines do not use it directly to keep the hottest parts of the engine cool. This is because of the corrosion which would be caused in the cooling water spaces, and the salts which would be deposited on the cooling surfaces interfering with the heat flow. Instead, the water circulated around the engine is fresh water ( or better still, distilled water) which is then itself cooled using sea water. This fresh water is treated with chemicals to keep it slightly alkaline ( to prevent corrosion) and to prevent scale formation. The Cooling Water Pump which may be engine driven or be a separate electrically driven pump pushes the water around the circuit. After passing through the engine, where it removes the heat from the cylinder liners, cylinder heads, exhaust valves and sometimes the turbochargers, it is cooled by seawater and then returns to the engine. The temperature of the cooling water is closely controlled using a three way control valve. A fresh water generator (FWG) which is used to produce fresh water from sea water is also incorporated
Pumps are machine use to transfer liquids from one location to another. A pump does not draw up a liquid, but rather creates a vacuum on the suction side allowing atmospheric pressure to push the liquid into the pump. Pumps can be divided into two main categories:
1. Positive displacement
Positive Displacement Pump
A positive displacement pump makes a fluid move by trapping a fixed amount and forcing (displacing) that trapped volume into the discharge pipe. Positive displacement pumps includes:
Progressive cavity pump
Rotary Gear pump
Screw pumpGear pump
Rotary vane pump
Regenerative (peripheral) pump
A rotodynamic pump is a kinetic machine in which energy is continuously imparted to the pumped fluid by means of a rotating impeller, propeller, or rotor. Examples of rotodynamic pumps include adding kinetic energy to a fluid such as by using a centrifugal pump to increase fluid velocity or pressure.
Types of Roto-Dynamic Pumps
SHIP’S COOLING SYSTEMS
The Cooling System
The purpose of the engine's cooling system is to remove excess heat from the engine, to keep the engine operating at its most efficient temperature, and to get the engine up to the correct temperature as soon as possible after starting. Ideally, the cooling system keeps the engine running at its most efficient temperature no matter what the operating conditions are.
In burning fuel in the cylinders of diesel engine, about 35% of the heat energy changes into mechanical energy, available as the shaft output, about 30% of the energy shows up in hot exhaust gases while the remaining 35% of the heat energy comprises the following: Frictional heat from the rubbing surface
Heating of the material walls, which form the combustion chamber.
FUNCTIONS OF THE COOLING SYSTEM
First is to remove 35% of the remaining heat so that there is no overheating of parts which will result in:
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