Beyond Geometric Scaling

2026-10-09

Toward Stage Optimization in AFC Architecture

The Question

As the internal diameter of an AFC chamber increases from 500 mm to 1000 mm, 1500 mm, and beyond, the chamber volume increases nonlinearly.

The central rod diameter, rod length, chamber height, and positions of the three air-curtain stages must also be reconsidered.

However, increasing every dimension proportionally does not necessarily produce an optimized oxidation environment.

Lessons from AFC-500

In the AFC-500 field prototype, approximately 40% of the chamber height was allocated to the first stage.

This was intentional.

Stage 1 was designed to accommodate waste loading, thermal decomposition, and overlapping primary oxidation processes.

During the initial field trials, used tires produced observable flame development through all three stages.

This demonstrated promising operating behavior under the tested conditions, although it did not establish that the stage proportions were optimal or that oxidation was complete.

The Missing Design Data

Earlier commercial implementations were largely developed through practical fabrication experience.

Although these systems provided valuable structural references, systematic data relating chamber diameter, chamber height, central rod dimensions, and stage proportions are not presently available to AZADrg.

Consequently, there is no established basis for assuming that a stage ratio suitable for AFC-500 will remain optimal for larger AFC chambers.

Geometry Is Not Performance

A larger chamber provides additional internal volume, but increased volume does not necessarily translate into a proportional increase in treatment capacity.

Effective capacity depends on interacting factors, including waste characteristics, gas generation rates, air distribution, mixing, temperature, residence time, and heat losses.

Likewise, the central rod should not be scaled solely according to chamber diameter. Its dimensions and air-injection arrangement must be evaluated in relation to the required flow behavior.

Toward a Design Method

Future AFC development should distinguish between two related design questions:

1. Geometric configuration: How should chamber height, central rod dimensions, and the three stage positions vary with internal diameter?
2. Oxidation performance: How do those configurations affect gas-phase oxidation, thermal stability, residence time, and emissions?

The approximately 40% first-stage allocation in AFC-500 provides an initial reference, not a universal design rule.

Further comparative testing and measurement will be required before optimized proportions can be established for different AFC sizes.

An Open Engineering Question

AFC architecture is intended to be locally reproducible.

For that reason, its design principles should eventually be expressed through understandable, measurable relationships rather than undocumented fabrication conventions.

The objective is not simply to build larger chambers. It is to understand how chamber geometry supports the formation and completion of a self-sustained oxidation flow.

This note documents an ongoing engineering investigation. No optimized stage ratios or scale-independent performance claims are established here.

🗃️Download AFC Scaling Simulation V1 (Excel)

Engineering Data — AFC Scaling Simulation V1

Preliminary geometric scaling model based on the AFC-500 reference configuration and an empirical AFC-2500 chamber diameter. The spreadsheet includes editable design assumptions and calculated Stage 1 volumes. It is intended for preliminary design exploration, not as a validated engineering specification.