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
- Simple and Compact in size
- Heat transfer efficiency is more
- Can be easily cleaned
- No extra space is required for dismantling
- Capacity can be increased by introducing plates in pairs
- Leaking plates can be removed in pairs, if necessary without replacement
- Maintenance is simple
- Turbulent flow help to reduce deposits which would interfere with heat transfer
Disadvantages
- Initial cost is high since Titanium plates are expensive
- Finding leakage is difficult since pressure test is not as ease as tube coolers
- Bonding material between plates limits operating temperature of the cooler
- Pressure drop caused by plate cooler is higher than tube cooler
- Careful dismantling and assembling to be done
- Over tightening of the clamping bolts result in increased pressure drop across the cooler
- Joints may be deteriorated according to the operating conditions
- Since Titanium is a noble metal, other parts of the cooling system are susceptible to corrosion
Shell and Tube Heat Exchangers
Advantages
- Less expensive as compared to Plate type coolers
- Can be used in systems with higher operating temperatures and pressures
- Pressure drop across a tube cooler is less
- Tube leaks are easily located and plugged since pressure test is comparatively easy
- Tubular coolers in refrigeration system can act as receiver also.
- Using sacrificial anodes protects the whole cooling system against corrosion
- Tube coolers may be preferred for lubricating oil cooling because of the pressure differential
Disadvantages
- Heat transfer efficiency is less compared to plate type cooler
- Cleaning and maintenance is difficult since a tube cooler requires enough clearance at one end to remove the tube nest
- Capacity of tube cooler cannot be increased.
- Requires more space in comparison to plate coolers
REFERENCES
“General Engineering Knowledge” by H.D. McGeorge