engleski

Jet impingement oven for bread baking: development and energy consumption

Because air impingement is recognized as an efficient way to obtain high heat transfer, the study deals with the development of a jet impingement oven dedicated to bread baking and its corresponding energy consumption. The treatment of large products such breads requires the arrangement of multiple jets in order to ensure the uniformity of the surface heat treatment. Numerical simulation was used for the conception of such an oven. First 2D numerical simulations were performed to evaluate the ability of the CFD commercial software to describe impinging jets. Then 3D numerical simulations were carried out for the conception of the oven. Based on numerical results and technical considerations a jet impingement oven was built, consisting in 21 cylindrical nozzles placed in the vault of the oven. A complete experimental characterization was performed for several set-point temperatures and inlet jet velocities. Results show that the heat transfer coefficient can reach 40 W/(m2 .K) for the highest air velocities and that the uniformity of the surface temperature of the sole is ensured by the multiple jets. Finally, energy consumptions were measured and compared to previous experimental results obtained in nearly the same oven (same baking chamber without jets). Results show that the set-point temperature for baking can be reduced to 180°C – 200°C (compared to 250°C) due to the highest heat transfer coefficient, resulting in a decrease of the energy consumption.

Chemical Engineering

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