Fouling mitigation on heat exchanger surfaces by EDTA-treated MWCNT-based water nanofluids

Abstract

Fouling can be defined as adherent deposits of unwanted compounds that are formed by the precipitation of soluble salts from water and crystal growth on the surfaces of processing equipment. The deposition layer becomes an insulating layer that deteriorates the heat transfer efficiency and shortens the service life. The development of functionalized nanomaterial leads to multi-functionality, such as the ability to adsorb scaling cations with high thermal conductivity, which is very important for heat transfer applications to manage the fouling problems. The purpose of this study was to evaluate the mitigation of calcium carbonate scaling by applying EDTA-treated MWCNT-based water nanofluids on heat exchanger surfaces. A set of fouling experiments was conducted by using additive EDTA-treated MWCNT-based water nanofluids (benign to the environment) to verify the additives’ retardation of the fouling rate of deposition. Fouling solution for deposit analysis was prepared by using 300 mg/L of artificially-hardened calcium carbonate solution. Also the assessment of the deposition of calcium carbonate on the heat exchanger surface with respect to the inhibition of crystal growth was conducted by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectrometry (EDS). The results showed that the formation of calcium carbonate crystals can be retarded significantly by adding MWCNT-EDTA additives to the solution.