Impact of airflow on the heat transfer conditions inside an oven cavity, characterized using particle imaging velocimetry

摘要

The complex airflow in convection ovens directly influences the heat transferred to the product placed inside, thereby affecting product quality. Characterization of related airflow profiles can provide scientific understanding for improvement of oven designs as well as important parameters for simulation of involved thermal processes. In this study, the particle-imaging velocimetry (PIV) technique was applied to visualize airflow inside a household convection oven with samples placed at three different locations on a baking tray. The oven cavity was modified for optical access, and airflow was measured at room temperature. A 30 mW green laser was used for illuminating tracer particles in a laser sheet that were generated using incense sticks. The flow patterns were captured using a high-speed camera at 1000 fps. The vorticity and turbulent kinetic energy parameters derived from velocity fields reflected adequate mixing of air inside the cavity. The computed heat transfer coefficient distribution from the boundary layer flow fields to the sample surface ranged between 2.0 and 183 W m(-2) K-1. The results showed separation of the laminar boundary layer from the object surface at angles of 85 degrees -90 degrees. The PIV-algorithms and boundary layer flow derived parameters developed in this study can be used for refined characterization of complex air or gas flows and related heat transfer characteristics in closed cavity convection ovens and the like arrangements. Published under license by AIP Publishing.