Because of a constant heat transfer in the self-cleaning heat exchanger, over dimensioning of the heat transfer surface is not required which results in a more compact design of the heat exchanger:
With a heat exchanger application known to foul, the required surface of the heat exchanger is normally calculated by adding a fouling factor to the heat transfer coefficient. Fouling factors can easily be 2 to 5 *10-4 m2K/W. Starting with an overall heat transfer coefficient of 2000 W/m2K, the heat transfer over time will drop to 1500 W/m2K or in the worst case to only 1000 W/m2K. So, for the same heat capacity, the heat exchanger needs an overdesign of 30 to 100% to meet the required capacity over time. With the self-cleaning heat exchanger overdesign is not required leading to a more compact design.
Besides the scouring effect of the particles, the fluidized bed in the fluid stream has an additional effect. The chaotic movement of the particles also breaks down the boundary layer and thereby strongly improves the heat transfer with a factor of around 4 at the same fluid velocity. Because the self-cleaning heat exchanger normally applies lower velocities the heat transfer improves with around 20% compared to that of a regular shell and tube heat exchanger.