Abstract
Abstract
Flow and spillage characteristics of conventional and air-curtain range hoods under static condition were experimentally studied, and their differences in physical mechanisms were compared. Two oil pans containing hot oils heated to 230°C by electric heaters were placed on a countertop to simulate the cooking condition. Large amount of oil fumes were generated and rose from the oil pans. Flow features were examined using laser-light-sheet-assisted oil fume flow visualization method. Local-averaged spillages of tracer gas (sulfur hexafluoride) in the front and lateral planes of the range hoods were detected by employing the tracer-gas concentration detection technique. For the conventional range hood, the flow visualization showed two most probable locations for spillages: the region near the front edge of countertop due to the boundary-layer separation and the region around the lower edge of the hood side panels due to the expansion effect of hot plumes. Detected local-averaged tracer-gas concentrations around these two locations correlated well with the results of flow visualizations. No significant spillages of oil fumes or tracer-gas concentration was observed or detected around the front and lateral planes of the air-curtain range hood. Around the front edge of countertop, the detected tracer-gas concentration of the conventional range hood was larger than that of the air-curtain range hood by about three orders of magnitude. Overall, the air-curtain range hood presented drastically smaller spillages than the conventional range hood.