What is Charge Air Cooler purpose ?
To reduce air temperature & increase density of charge air.
All more fuel can be burnt more power can be obtain
Reduce exhaust temperature and engine thermal load.
Increase scavenging efficiency, safe working temperature.
Cooler maintenance for optimum efficiency
1. Cooler should be checked any deposit of line, scale or oil sludge may be present in cooler it should be cleaned.
2. Cooler of water side can be done with soft tube brush and oil side with carbon tetra chloride solution in reverse direction to normal flow with hand pump for about 4 hours.
3. After cleaning the cooler are hydraulically pressure tested normally 1.5 times the working pressure.
4. It 10% of the tubes have been leaked retubing in necessary. Normal leaking tubes may be stopped by plugging.
5. Corrosion can be protected by means of preservative coating (Anti corrosive paints) inside the shell and water boxes and by means of anodes such as zinc fitting inside water boxes.
6. Essential cooler for optimum efficiency can be maintained by controlling of temperature of fluid or sea water.
Purpose of division plate
1. To providing to increase numbers of pass
2. This increase the cooling efficiency.
What do you know L.O cooler leakage ? How to do L.O cooler leakage occur ?
When engine run,
01) Oil comes out at the cooling water overboard.
02) Sump tank oil level will fall down.
03) L.O pressure will drop
04) If L.O cooler leaks the engine should be stopped with permission from bridge. The leakage can be detected by carrying out a hydraulic pressure test to the oil side.
05) After cooling down the engine stop main circulating L.O pump and main S.W cooling pump.
06) Close necessary valve of them
07) Open water box covers cooler both side.
08) Blank off discharge pipe of cooler oil side.
09) Connect hydraulic pump to inlet of cooler.
10) Apply oil pressure normally 1.5 times the working pressure. Then check the leakage at cooler both sides
11) Normally leaking tubes may be stopped by plugging
12) If 10% of the tubes have been leaked retubing is necessary.
13) Then the engine is put back normal running.
How do you know air cooler leakage ?
01) Check water level insight glass fitted at cooler drain pipe.
02) Drain the cooler / taste the water
03) If the water continuous comes out, the cooler is leakage. Also in the funnel white & dense smoke.
04) Thus the engine should be stopped with permission from bridge.
05) Normal leaking tubes can be stopped by plugging.
06) Then the engine is put back normal running.
How to check cooler efficiency ?
01) Check sea water in/out temperature difference. Less amount poor efficiency of cooler (must be high)
02) Check coolant medium in / out temperature (Difference temperature: should be low)
03) Feel over cooler shell, upper hot, middle warm, down cool is normal.
04) Check pump and by pass valve.
Purpose of baffle plate
01) To prevent the tube
02) To guide the flow of fluid
03) To increase cooling surface area
04) To minimize the tube vibration
Cause of loss of vacuum effect in F.W.G
(01) Failure of ejector pump
(02) Failure of ejector nozzle (fouling, erosion)
(03) Malfunction of check valve (at ejector nozzle)
(04) Defective vacuum breaker
(05) Any air leakage into the system (At joint)
What will happen while vacuum reach 100%
1) Increase the salinity because of agitation. AT that time boiling rate is very high.
2) To control this condition: I open the vacuum breaker to maintain 93% vacuum.
Why F.W.G is fitted onboard ship ?
1) To produce the high purity distilled water from sea water
2) To provide make up water fro boiler and portable water for drinking and domestic used. So can save cost.
Treatments for drinking purposes.
Sterilizing methods.
Chlorination.
Ultra violet light.
Libration of silver ions from the consumable.
Improving the platability.
Osmosis.
Different concentration solutions are separated by a semi-permeable membrane. Water from less concentrated solution pass through the membrane to equalize the concentration of the two solution. It create hydraulic pressure gradient across the membrane as the volume and level of weaker solution fall and those of the stronger solution rise.
Reverse osmosis.
The pressure greater than the osmotic is applied to the side of higher concentration, the process is reversed. Water from the stronger solution is forced back through the semi-permeable membrane to dilute the initially weak solution on the other side and further increase the concentration of the strong solution.
The total pressure required for this process consists of the osmotic pressure(between 4 bar for brackish water up to 28 bar for sea water) plus the system pressure losses and net driving pressures (around 25 bar).
Membranes
1. Hollow fine fiber (aromatic polyamide or cellulose acetate spurn to form hollow fiber)
2. Spirally wound (cellulose acetate for backish water and polymide or polysulphonate for sea water.)