Industrial and Marine Intercoolers

A heat exchanger is a device for transferring heat energy from a liquid or gas, to another liquid or gas without the two ever coming into contact with each other. A typical shell and tube heat exchanger will contain a tube bundle inside an outer shell, or body. Cold water flows through these tubes, whilst hot water, or gas flows around the outside of the tubes, enabling the heat from the hot water or gas to be transferred to the colder water inside the tubes.

A good example of how the process works are swimming pools, where most are heated via a boiler, using Gas, LPG or Biomass as the energy source. In theory, the most efficient way to heat the pool would be to circulate the pool water directly through the boiler. But were this to happen, the chemicals used in the pool water to keep it safe for use, would quickly corrode and damage vital parts inside the boiler, leading to premature failure and a costly replacement.

However, by using a heat exchanger to act as an ‘interface’ between the boiler water circuit and the pool water circuit, the boiler is protected from damage and the pool water is quickly heated up to the required temperature; the pool water passing through the central ‘tube core’, whilst the hot boiler water circulates around the outside of the tubes, transferring heat energy to the pool water.

More examples of applications where Bowman heat exchangers are used.

In a shell and tube heat exchanger, coolant usually flows through the central ‘tube core’ to cool hot oil, water or air, which passes over and around the tubes. The direction in which the two fluids travel through the heat exchanger can be either ‘parallel flow’ or ‘counterflow’.

Parallel flow is where the fluid to be cooled, flows through the heat exchanger in the same direction as the cooling medium. Whilst this arrangement will provide cooling, it has limitations and can also create thermal stress within the heat exchanger, as one half of the unit will be appreciably warmer than the other.

In counterflow cooling, the incoming cooling medium absorbs more heat as the ‘hot’ fluid travels in the opposite direction. The cooling medium heats up as it travels through the heat exchanger, but as colder water enters the heat exchanger it absorbs more heat, reducing the temperature much lower than could be achieved with parallel flow.

The mean temperature difference between the cooling medium and the fluid being cooled is also more uniform along the length of the heat exchanger, reducing thermal stress.

Depending on flow rate and temperature, the heat transfer performance could be up to 15% more efficient with counterflow, possibly enabling a smaller heat exchanger to be used, saving space and money!

More information on the benefits of counterflow.

During the course of its operating life, a shell and tube heat exchanger will need cleaning many times. Both fresh water and sea water cooling media today contain high levels of minerals and pollutants, which can build up over time, restricting the water flow through the tube core, resulting in a reduced flow rate and significantly lower heat transfer efficiency.

The good news is that Bowman shell and tube heat exchangers are much easier to clean than many other types and the following information is intended as a basic guide:

1. Removing the end covers gives access to the tube core, which can be removed from the body (or shell).
2. The tube plates and external tubes can then be washed using a handheld hose or lance. A steam cleaner can also be used, if available.
3. Small diameter rods or tube brushes can be used to clean through each tube to remove any stubborn deposits.
4. Detergents or chemicals can be used, if tube fouling is severe. Allow plenty of time for the cleaning media to work before hosing down with plenty of water. NOTE: it is important to check any cleaners being used are compatible with the tube material.
5. Thoroughly flush the tube core with clean water to remove all traces of cleaning chemicals/detergents and if necessary, neutralise the cleaning fluid.
6. Reassemble the tube core into the body, refit the end covers in their original orientation and tighten to the recommended torque figures – NOTE: always use new ‘O’ seals after cleaning to ensure a watertight joint.

For more detailed information on care and maintenance of your Bowman heat exchanger or oil cooler, download a copy of our ‘Installation, Operation & Maintenance guide’.