Rectangular heat exchangers offer some features that benefit heat recovery applications in wastewater.
1. They offer a larger circumference compared to tube in shell. For the same flow area, there is a larger heat transfer surface.
2. They offer a smaller footprint than a tube, which means less area is required.
3. More turbulence flow is available than in a tube or spiral unit, which provides better heat transfer due to zig-zag channels.
4. The non-block design means there’s no spacer or obstacles like in a spiral type.
5. One feature ― 3" minimum gaps ― results in no sludge blockage. Often this eliminates the need for blades used to grind sludge.
6. Little maintenance is required.
7. Modular systems can be used for water-to-sludge or sludge-to-sludge heat recovery.
8. Heat recovery can have payback within a year.