Silicon carbide heat exchangers, due to their superior material properties, exhibit significant advantages in anti-fouling performance. However, their actual performance is still influenced by a combination of multiple process parameters. From material properties to structural design, from fluid dynamics to operating conditions, parameter optimization at each stage directly affects the anti-fouling capability and long-term stability of the silicon carbide heat exchanger.
The physicochemical properties of silicon carbide are fundamental to its anti-fouling properties. Its high surface smoothness and significantly lower roughness compared to metallic materials reduce adhesion points for dirt particles, making it difficult for dirt to deposit on the surface. Simultaneously, silicon carbide's excellent hydrophobicity makes it difficult for water molecules to form a stable water film on its surface, further reducing the probability of inorganic salt dirt crystallization and adhesion. Furthermore, silicon carbide's strong chemical inertness ensures stability in most acidic and alkaline media and organic solvents, avoiding dirt deposition caused by micro-cell effects or chemisorption resulting from material corrosion.
Fluid dynamics design directly affects the balance between dirt deposition and stripping. Optimizing the arrangement of heat exchanger tube bundles, such as using a spiral winding structure or a cross-flow arrangement, can enhance the turbulence intensity of the fluid in the tube side. The shear force generated by turbulence can continuously scour the tube wall, causing already attached micro-fouling particles to detach from the surface in a timely manner. Simultaneously, reasonable control of the fluid flow rate is crucial—too low a flow rate will cause the fouling deposition rate to exceed the removal rate, while too high a flow rate will increase the pressure drop and energy consumption of the equipment. In practical applications, the optimal flow rate range needs to be determined through CFD simulation based on parameters such as medium viscosity and particulate matter content.
Surface treatment processes can further improve anti-fouling performance. Depositing a diamond-like carbon (DLC) coating on a silicon carbide substrate can increase the surface hardness to over 20 GPa while reducing surface energy, making it easier for fouling particles to be carried away by the fluid. For media containing a high amount of organic matter, a polytetrafluoroethylene (PTFE) spraying process can form a dense oleophobic layer, preventing organic molecules from adsorbing and agglomerating on the surface. Furthermore, laser-engraved micro/nano structures can alter the fluid boundary layer characteristics, inhibiting fouling deposition through microscale eddy current effects.
Among the operating parameters, temperature and pressure have a particularly significant impact. High-temperature environments accelerate the crystallization rate of salts in certain media, but the high thermal conductivity of silicon carbide (120-270 W/(m·K)) allows for a more uniform temperature distribution on the pipe wall, preventing localized overheating that could exacerbate scaling. Pressure changes affect the solubility of the media; for example, under reduced pressure conditions, the release of dissolved gases may form bubbles that aid in scale removal. Establishing a correlation model between operating parameters and scaling rates using digital twin technology allows for dynamic optimization of these parameters.
The composition of the media is a key factor determining the type of scaling. Hard water containing high concentrations of calcium and magnesium ions easily forms carbonate scale, while media containing organic acids or polymers may produce organic scale. Silicon carbide heat exchangers inhibit the formation of chemical scale through material inertness, while their thermal shock resistance (withstanding 50 cycles of rapid cooling and heating) prevents inorganic scale peeling and redeposition cycles caused by drastic temperature changes. For media containing solid particles, a wide-channel design (e.g., trapezoidal channel width ≥ 5mm) combined with surface polishing can reduce the risk of particle blockage.
Regarding equipment structure optimization, the modular design supports independent replacement of individual tube bundles, facilitating targeted reinforcement of areas prone to fouling. The microchannel silicon carbide heat exchanger (channel size < 1mm) enhances heat transfer efficiency through a significantly larger specific surface area (up to 5000 m²/m³), while simultaneously reducing the threshold for the impact of fouling layer thickness on heat transfer. A double-sealed structure and leak-proof design prevent secondary fouling caused by media leakage.
Intelligent maintenance technology provides long-term assurance for anti-fouling performance. An integrated ultrasonic thickness gauge monitors changes in heat exchanger tube wall thickness in real time, triggering a cleaning program when local thinning exceeds a threshold. An electrochemical impedance spectroscopy sensor detects the state of the surface passivation film, providing early warning of potential corrosion risks. A digital twin system combined with AI algorithms can simulate fouling growth trends under different operating conditions, optimizing cleaning cycles and methods. For example, a combined strategy of high-pressure backwashing and chemical cleaning can be employed to extend equipment operating cycles while ensuring cleaning effectiveness.
