February 2023 Volume 5

EQUIPMENT & TECHNOLOGY

alloy cylinder was the chosen heat treatment process. In addition, a simple but effective simulation approach was performed using a commercial software to perform the finite element analysis. The measured information was obtained from the aluminum alloy cylinder wired with several thermocouples at different depths (Figure 2).

When the simulation´s results resemble the measured information, the added value of using a software tool is not only to approach the measured data, but the calculation of heat transfer coefficients that are very difficult to measure (Figure 5).

Figure 5: Heat transfer coefficient of two testing conditions (a) forced air low velocity (b) forced air high velocity. Conclusion An air-mist cooling system prototype was designed, and its cooling performance was evaluated with different air velocities and water volumes. The calculated h demonstrated a cooling improvement of 20 – 70 %when a high volume of water mist was used. Using an air-mist cooling system could lead to improvements on equipment design and cooling rates, which could apply not only in aluminum alloy’s quenching applications but also to a wide variety of other types of heat-treatable alloys that need their cooling performances to be controlled in an accurate way to prevent undesired precipitations, phase changing, residual stress, or even distortion. Francisco J. Flores Gatica

Figure 2: Aluminum cylinder placed over the cooling system’s nozzles and sketch of thermocouple positions. Using the mentioned arrangement, information was obtained from the surface where the heat transfer takes place mostly by forced convection and from the interior, where heat transfer is due to conduction. For the simulation, establishing the boundary conditions (Figure 3) is important to ensure the calculation is performed within the limits of our system in this case, the simplicity of our set-up helped to have the consideration of a vertical flow for the convective part only.

Francisco has worked in Research and Development for the heating solutions industry and process engineering for the aluminum industry. Holds a B. Sc. in Chemistry from the Technology of Monterrey. He is currently a Doctor of Engineering candidate at Autonomous University of Nuevo León. He can be reached by e-mailing franciscoflores@nutec.com

Figure 3: Scheme configuration used for the 2-D axis symmetrical analysis and boundary conditions used. Analysis in the 2-D axis symmetrical was performed to simulate the cooling curves gathered by air quench conditions and the temperature behavior over the cooling period was compared (Figure 4).

Figure 4: Temperature propagation in the workpiece and calculated vs. measured cooling curves.

FIA MAGAZINE | FEBRUARY 2023 9