Marine Engineering Study Materials

Both plate type and shell and tube heat exchangers are normally used on ships. Both type of heat exchangers have advantages and disadvantages.

Plate Type Heat Exchangers

Advantages

1. Simple and Compact in size
2. Heat transfer efficiency is more
3. Can be easily cleaned
4. No extra space is required for dismantling
5. Capacity can be increased by introducing plates in pairs
6. Leaking plates can be removed in pairs, if necessary without replacement
7. Maintenance is simple
8. Turbulent flow help to reduce deposits which would interfere with heat transfer

Disadvantages

1. Initial cost is high since Titanium plates are expensive
2. Finding leakage is difficult since pressure test is not as ease as tube coolers
3. Bonding material between plates limits operating temperature of the cooler
4. Pressure drop caused by plate cooler is higher than tube cooler
5. Careful dismantling and assembling to be done
6. Over tightening of the clamping bolts result in increased pressure drop across the cooler
7. Joints may be deteriorated according to the operating conditions
8. Since Titanium is a noble metal, other parts of the cooling system are susceptible to corrosion

 

Shell and Tube Heat Exchangers

Advantages

1. Less expensive as compared to Plate type coolers
2. Can be used in systems with higher operating temperatures and pressures
3. Pressure drop across a tube cooler is less
4. Tube leaks are easily located and plugged since pressure test is comparatively easy
5. Tubular coolers in refrigeration system can act as receiver also.
6. Using sacrificial anodes protects the whole cooling system against corrosion
7. Tube coolers may be preferred for lubricating oil cooling because of the pressure differential

Disadvantages

1. Heat transfer efficiency is less compared to plate type cooler
2. Cleaning and maintenance is difficult since a tube cooler requires enough clearance at one end to remove the tube nest
3. Capacity of tube cooler cannot be increased.
4. Requires more space in comparison to plate coolers

 

REFERENCES

“General Engineering Knowledge” by H.D. McGeorge