Fluent's consulting group helped Mobil Technology Company find the best solution for efficiency improvements of a heat exchanger-reactor, resulting in a 25% gain in potential active volume with relatively minimal design modifications. By creating a simplified CFD model adaptable to various redesign routes with minimal regridding, Fluent's consulting service group significantly reduced the time required to assess alternatives.

The heat exchanger geometry is comprised of three different baffle types, which were modified to improve fluid flow.

After modification, there is no recirculating fluid between baffles, and almost uniform flow distribution.

The heat exchanger configuration includes three different types of baffles designed to direct flow through the shell in parallel paths, with two injector points where reactant is added. To simplify the geometry and save time, the tube bundle sections are modeled as non-isotropic porous media. Model results for the original configuration show non-uniform flow distribution with one of the parallel paths taking most of the fluid, reducing the apparent volume efficiency of the unit. The first modification is to relocate and reorient the injectors. This significantly improves flow uniformity, but also reveals areas of undesired recirculation. The second modification involves changing the cut of one of the baffles. The result is no recirculation and almost uniform flow distribution.

Greg Muldowney of Mobil explains his reasoning for using Fluent Consulting. "In a project with very little time to spare, we pursued multiple CFD analyses to identify exchanger inefficiencies and evaluate redesigns. I called on Fluent Consulting for the shell simulation because it required a large grid which we knew would be revised many times, and their expertise in constructing models within short time constraints has been demonstrated in past work with us. With the simplified model we reached a feasible redesign option in time to impact commercial decision-making. The results showed the potential for at least 25% increase in capacity."

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