Compared to traditional suction and air intake methods, the casing's heat exchange capacity increases by ΔQ=4.7W. However, this improvement is relatively small when considering the overall design and development of hot oil flue gas in the center of the pot. The front and side cold air rapidly draws the negative pressure center upward, while the vacuum created by the hot oil smoke from the sides is replenished, causing the soot-laden airflow to spread forward and sideways. The top suction opening is positioned higher, leading to more intense diffusion and turbulent flow. When the cooker is close to the stovetop, it blocks the cold air from entering the front, forcing all the airflow to consist of hot oil smoke and exhaust. Currently, top-loading range hoods are popular in Hong Kong, Japan, Italy, Canada, and other regions, but their oil fume extraction performance is not ideal. The general purification rate is below 50%. Top suction systems do not achieve full efficiency; they mainly rely on wind dynamic efficiency. Due to the low efficiency, the comparison between electric fans is not significant. Additionally, top suction range hoods face higher resistance and lower motor efficiency.
Oil and grease contamination can be categorized into saturated and unsaturated fatty acids. Saturated fatty acids are more stable due to their single bonds, while unsaturated fatty acids are more prone to forming toxic polymers. Animal oils contain a higher proportion of saturated fats and have poor fluidity, whereas vegetable oils are richer in unsaturated fats and are more fluid. The high-temperature oil vapor extracted by top suction range hoods mixes with water vapor and ambient air—both much cooler than the boiling point of the oil. This rapid cooling, combined with the stirring and collision caused by the fan blades, causes tiny oil droplets to coalesce and adhere to the fan blades or the inner walls of the cavity. Some of the unsaturated oil may flow into the oil collection tank, while water vapor typically does not remain in the cavity at normal temperatures. As the fumes pass through the duct, more grease tends to accumulate. When the range hood is not in operation, the air inside the chamber remains still, allowing dust and fibers to settle and mix with existing oil layers, eventually forming thick oil deposits over time.
Dual-Motor Standing Desk Frame
Dual-Motor, Standing Desk Frame, Standing Desk
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