Innovative non-metal heat transfer surfaces to mitigate crystallization fouling

Abstract

In this study, non-metal silicon carbide (SiC) substrates were used as non-adhesive heat transfer surfaces to eliminate the negative impacts of crystallization fouling of CaSO4 solutions. The experimental results showed that the SiC substrates, to large extent, were able to mitigate scaling in terms of lower initial fouling rates by as much as four-fold to that of baseline stainless steel (SS) substrates. The superiority can be related to the unique surface characteristic of SiC substrates in terms of higher value of the electron donor component which was 8 times higher than SS surfaces. The post-fouling examination of deposit layers revealed that the layers were very porous where only few number of crystal clusters formed on the surfaces. The deposited crystal clusters, to some extent, were also non-stickable as such that they dropped off the surface completely after each dismantling from the test rig. Larger porous deposit layer on SiC substrates showed also better thermal performance compared to similar tests for the SS substrates. The fouling runs of SiC surfaces showed similar propensity for different surface temperatures, where a reduction of surface temperature by 10 °C resulted in 89% lower initial fouling rate which is noticeable for implementation in industry. The low stickability of the deposit layer on SiC surfaces would implicitly indicate much less hazardous chemical inhibitors and/or cleaning agents would be required to clean the surface from formed deposits.