Various heat exchangers are available onboard. Types vary depending on the usage.
It is commonly termed as cooler, heater and condenser.
7.13.1 Types of Heat Exchangers:
a. Shell and Tube type Heat Exchanger
Shell and tube type heat exchanger is the most common type of heat
exchangers. As its name implies, it employs the shell and the bundle of tubes.
One fluid runs through the tubes, and another fluid flows over the tubes (through
the shell) to transfer heat between the two fluids. The set of tubes is called a tube
bundle, and may be composed by several types of tubes: plain, longitudinally
finned, etc. Various designs are available for this type of heat exchanger.
b. Plate Type Heat Exchanger
This is another type of heat exchanger. It is composed of multiple, thin, slightlyseparated
plates that have very large surface areas and fluid flow passages for
heat transfer. This stacked-plate arrangement can be more effective, in a given
space, than the shell and tube heat exchanger. Normally, the plate are separated
and sealed by a gasket to allow periodic disassembly, cleaning, and inspection.
c. Performance Requirements
The heat exchangers are designed to provide cooling, heating and condensing
process in a system.
To ensure that the performance requirements are met, check your maker’s
instruction manual for proper operation, adjustments and maintenance
procedures as this may affect the over-all efficiency of the device.
i. Plugged Tubes
In some cases, due to leakage of the tubes and necessitate to isolate such tube,
plugging is being conducted. When this process is done, the efficiency is reduced
and the actual performance may not be obtained. In general, the number of tubes
allowed to be plugged and to maintain the heat exchanger in operation must be
less than 30% of the total number of tubes. When the number of tubes plugged
exceeded more than 30%, the performance requirements is fully sacrificed. In
any cases, maintain the tubes in good condition to attain the over-all performance
of the heat exchanger.
ii. Plates Gaskets
When operating a plate type heat exchanger, precautionary measure shall be
applied especially to the condition of the gasket and the pressure of the cooling
media. When the gasket is not properly fixed in the plate, leakage of cooling
media may occur and the possibility of mixing or contaminating the other media in
the heat exchanger. Make sure that the gaskets are fully fixed and kinking is not
allowed. Make sure to adjust the flow rate and the pressure of the cooling water
media at pump delivery and the heat exchanger inlet valve. Never adjust at the
outlet valve as this may cause over pressure of the cooling water that may
damage the gaskets.
iii. Anti- Corrosion Plate or Plug (Zinc Anode)
Make sure to inspect and clean the anti corrosion plate or plug periodically. This
material is preventing the scale formation in the cooling water side. When the
anode is not working replace it with a new one. Scaling reduces the performance
efficiency of the heat exchangers.
