Heat Exchanger is a unit through which heat is transferred from one fluid to another. The solution in the Heat Exchanger can be separated by preventing the direct contact of the liquids. The internal combustion engine is a good example of the Heat Exchanger as it regulates the coolant through radiator coils. Parallel flow, cross flow and counter flow are the three main categories of exchangers, which are divided on the basis of flow arrangement.
The Heat Exchanger transfers heat from one place to another at different starting temperature. If the Heat Exchanger has only one phase then it is termed as Single Phase Heat Exchanger whereas if it has two phases it is termed as Two Phase Heat Exchanger. It is used as a boiler in large power plants and can also be used as a condenser in steam-driven turbines. Different exchangers have different tube diameters, axial strength, tube lengths, hoop strength and buckling strength. The exchangers are designed to enhance the surface area of the wall between two fluids.
How to increase the lifetime of a Heat Exchanger
Heat exchangers are manufactured from robust materials, have no moving parts and operate at a variety of different pressures and temperatures, therefore if a heat exchanger is used in the correct way then there is no reason why it shouldn’t be able to remain operational for many years. To help increase the operational lifetime of a heat exchanger there are several steps that should be taken;
Make sure the design data is accurate – If you are sending data to our engineers for heat exchanger selection, then it is best to make sure that it is as accurate as possible. Not only will this ensure that your heat exchanger is thermally efficient but also that it will be able to operate for a long period of time. If the flow rates are too high then erosion could be a problem, if the pressures are too high then leaks could occur and if there are any unusual chemicals in the fluids (such as acids in coolant water) then please contact us to check the compatibility. If our standard materials aren’t suitable then we can usually supply an alternative which is.
Commission and Installation – When installing your heat exchanger, make sure that correct fittings and pipe work are used. If unsure, please check the Thermex Installation and Operation Manual for details. For heat exchangers on applications which use polluted, shallow or brackish sea water as the coolant and have copper alloy tubes, it is recommended to run the heat exchanger in clean sea water for several weeks first, this creates a protective layer over the tube material which helps to protect against corrosion. Where possible, filters should also be used where fluids may contain solid particles to prevent tube erosion from occurring.
Regular Maintenance and Servicing – All Thermex shell and tube heat exchangers are designed to allow for easy maintenance and servicing. The end caps can be removed allowing the internal tube bundle to be removed for cleaning. New seal kits can also be provided from stock and are available to purchase on our Web Shop. For information and tips on servicing your heat exchanger, please see the Thermex Installation and Operation Manual.
What causes a heat exchanger to fail in operation?
There are many possible causes for heat exchanger failure, some examples for shell and tube include;
| Symptom | Possible Cause | Possible Solution | Prevention |
| Oil and Water Mixing | O Ring failure |
Normally a seal kit is all that is required to solve the problem, but temperatures should be checked to make sure that the seals purchased are suitable. |
Before purchasing an Oil Cooler, make sure that Thermex are aware of the pressures and temperatures being used. |
| Split Tube | |||
| Erosion on the tube plate face | Water velocity is too high | Check water flow rate and advise Thermex. In some cases a higher grade of material such as 70/30 CuNi or Titanium may be required. | When using sea water, make sure that the flow rate doesn’t exceed the Heat Exchanger’s capabilities. Contact us for advice. |
| Header / End cap split | Frozen water expanding within the heat exchanger / Oil Cooler. | New header kit and Seal Kit will be required. | Drain the water system during the winter if the cooler isn’t being used. |
| Insufficient thermal capacity, or reducing performance. | Operating conditions not matching design conditions | Review design conditions and operating conditions with Thermex engineers, a new tube stack or pump may be required. | Ensure that operational data provided to Thermex is as accurate as possible. |
| Sediments, dirt or other blockage inside the heat exchanger | Remove headers to check tubes, clean with a suitable fluid or pipe cleaner. | Use a filtration system to prevent blockages within the tubes, or increase cooling water flow rate. | |
| Too many plugged tubes | New tube stack will be required. | Avoid taking action which will block tubes or reduce the number of them in operation. |