What is a Plate Heat Exchanger?
A plate heat exchanger is a device that enables the heat emanating from one liquid to cool or heat another. A basic law of physics states that heat leaves the hottest fluid and transfers to the colder fluid. Basically, that is what a plate heat exchanger is all about.
What is a plate heat exchanger design?
The design is simple and resembles a sandwich. It comprises two, usually rectangular, plates (the slices of bread) in which the two different liquids are stored, on top of each other, separated by a thin, highly conductive wall (the sandwich filling). Plate heat exchangers come in many different sizes. Those that deploy gaskets as a means of stopping leakage can usually facilitate the addition of additional plates and may be cleaned by dismantling each plate; in welded or brazed exchangers, it is not possible to add additional plates, and the entire unit can be removed for cleaning off-site.
Plate heat exchanger calculation
If you are installing a plate heat exchanger, you need to know whether it will provide the performance you need. You may therefore need to do some calculations which are quite complex. The calculation needs to take in a number of factors, including:
- Heat load
- The temperatures that the heat enters and leaves the plates
- The flow rate on both sides of the plates
If this sounds technical, don’t panic, there are applications available on the Internet that will help you with the calculation.
Types of heat exchangers
There are other types of heat exchangers in addition to plate heat exchangers. Shell and tube heat exchangers comprise a number of tubes, brigaded in bundles within a cylinder. The tubes contain hot and cold fluids which work in a similar way to how a plate heat exchanger operates. Shell and tube exchangers are favoured in the marine industry because they are easy to maintain even though they are not as efficient as plate heat exchangers.
Air exchangers, as the name suggests, use air as the cooling medium. Air exchangers have a wide application in the vehicle industry, in military vehicles, agricultural machinery and diesel and petrol engines.
Finned tube exchangers are an enhanced version of shell and tube exchangers where fins are added to each tube, significantly increasing the surface area.
It is worth remembering that of all heat exchangers, flat plate heat exchangers are regarded as the most efficient; the fact that plate heat exchange works on the basis of counter-current flow rather than co-current flow is a primary factor in this. There are different types of plate exchangers that offer different benefits depending on what you are using the exchanger for. These include vacuum brazed, dip brazed, and welded.
A final word
A detailed introduction to heat exchangers, their designs and applications would take many pages. I hope that I will have at least covered first-base for those thinking about their heat exchanger requirements and that I have answered the question, what is a plate heat exchanger?