Swirling liquids in a reactor with textured inner surface.

Supercharge Your Reactors: How Surface Roughness and Swirl Flow Can Maximize Mass Transfer

Elliot Brynn in Tech & Innovation December 2025 • 4 min read.

"Unlock the secrets to optimizing chemical and electrochemical reactors with innovative techniques combining surface roughness and swirl flow for enhanced efficiency."

In the world of chemical and electrochemical engineering, annular flow reactors are essential tools. These reactors, which feature a cylindrical space between two concentric tubes, are favored for their ability to handle liquid-solid diffusion-controlled reactions. Their design offers several advantages, including efficient heat removal, uniform current and potential distribution, and a compact footprint.

However, the limited surface area within these reactors often restricts their overall production rate. To overcome this limitation, researchers have explored various methods to enhance mass transfer, such as gas sparging, vibration, inner tube rotation, gas generation, and surface modification.

This article delves into an innovative approach: combining surface roughness with swirl flow. While previous studies have examined swirl flow in smooth annular reactors, the synergistic effect of combining it with surface roughness remains largely unexplored. We'll unpack how strategically designed surface roughness, coupled with the dynamics of swirl flow, can significantly amplify mass transfer rates.

The Science Behind Enhanced Mass Transfer: Roughness and Swirl

Swirling liquids in a reactor with textured inner surface.

The study whose details are outlined in the rest of this article sought to boost the rate of mass and heat transfer within an annular reactor by strategically integrating swirl flow and surface roughness. Surface roughness achieves this by increasing turbulence and expanding the reactor's effective surface area, thereby accelerating production rates.

To understand how these methods work, the team of researchers looked at: solution velocity, degree of roughness, physical properties of the solution, height of the inner cylinder, and effect of drag reducing polymers. The experimentation was conducted using an electrochemical technique, measuring the limiting current of the cathodic reduction of K3Fe(CN)6 in an excess of NaOH as the supporting electrolyte. By measuring the impact of surface roughness on the rate of mass transfer, the scientists obtained data that can inform reactor design for optimal performance.

Surface Roughness: Achieved by cutting longitudinal V grooves into the inner cylinder, transverse to the swirl flow.
Swirl Flow Generation: A tangential feed nozzle introduces the solution into the annulus, creating a swirling motion.
Electrochemical Technique: Measures the limiting current of the cathodic reduction of K3Fe(CN)6 to determine mass transfer rates.
Drag-Reducing Polymers: Used to assess their impact on mass transfer rates in the presence of swirl flow and surface roughness.

The results speak for themselves. The mass transfer data obtained from the rough cylinder were correlated using a dimensionless equation, providing a quantitative relationship between the Sherwood number (Sh), Schmidt number (Sc), Reynolds number (Re), cylinder height (L/de), and roughness (e/de). Moreover, the study found that drag-reducing polymers can reduce the rate of mass transfer by 5 to 23%. This is in part due to the polymers suppressing turbulence, which then inhibits the mass transfer processes.

Implications for Future Reactor Design

This research offers valuable insights for designing and optimizing high-yield reactors. The findings are particularly relevant for electrochemical and biochemical reactors that use immobilized enzymes. Moreover, the benefits extend to membrane processes using corrugated membranes. By understanding and applying the principles outlined in this study, engineers can create more effective and efficient reactors for a wide range of applications.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.4172/2157-7048.1000319, Alternate LINK

Title: Effect Of Surface Roughness On The Rate Of Mass Transfer At A Vertical Cylinder Under Swirl Flow In Relation To Electrochemical And Catalytic Reactor Design

Subject: General Medicine

Journal: Journal of Chemical Engineering & Process Technology

Publisher: OMICS Publishing Group

Authors: Mustafa Sa, El Gayar Da, Sedahmed Gh

Published: 2016-01-01

Everything You Need To Know

What is an annular flow reactor and why is it important?

An annular flow reactor is a type of chemical reactor that features a cylindrical space between two concentric tubes. These reactors are favored in chemical and electrochemical engineering due to their ability to handle liquid-solid diffusion-controlled reactions. The design provides efficient heat removal, uniform current and potential distribution, and a compact footprint. The surface area limits the overall production rate; therefore, methods to enhance mass transfer are essential.

How does surface roughness enhance mass transfer?

Surface roughness involves modifying the surface of the inner cylinder in an annular reactor, such as by cutting longitudinal V grooves. This modification increases the turbulence of the solution flowing through the reactor. The increased turbulence expands the effective surface area, which directly enhances mass transfer rates. This is a key method to increase efficiency and production yield in the reactor.

What role does swirl flow play in the reactor?

Swirl flow is generated in the annular reactor by introducing the solution tangentially into the annulus using a tangential feed nozzle, creating a swirling motion. This swirling motion increases the mixing within the reactor, enhancing mass transfer by improving the contact between reactants and the reactive surface. Combining swirl flow with surface roughness creates a synergistic effect, further amplifying mass transfer rates. This is critical in optimizing reactor performance and increasing production yields.

How is the electrochemical technique used to measure mass transfer?

The electrochemical technique measures the limiting current of the cathodic reduction of K3Fe(CN)6 in an excess of NaOH. This process allows the researchers to determine the mass transfer rates within the reactor. By analyzing the changes in the limiting current, scientists can quantify the impact of surface roughness, swirl flow, and other factors on the efficiency of the reactor. This data is essential for optimizing reactor design and performance.

What is the impact of drag-reducing polymers in the reactor?

Drag-reducing polymers can be added to the solution to assess their impact on mass transfer rates. The study indicates these polymers can reduce the mass transfer rate by 5 to 23%. This reduction is attributed to the polymers' ability to suppress turbulence, which is crucial for mass transfer processes. This suppression inhibits the mixing and contact between the reactants and the reaction surface. This finding is important in reactor design as it highlights the need to consider the impact of additives on reactor efficiency.