本研究針對雙背吸式(Dual Back Suction, DBS)排油煙機之靜態流場及檯前有假人站立對其性能的影響做實驗分析，探討流場與洩漏的特性。雙背吸式排油煙機擁有數個特徵結構：(1)一狹縫型吸氣槽、(2)十二個橫狀排列的輔助吸氣孔、(3)一狹縫型吹氣槽、(4)兩面側板前方設計一三角形結構、(5)入口邊界層分離控制器。使用雷射輔助煙霧可視化技術，觀察排油煙機在不同火力與吸氣量搭配下流場的特性，推測洩漏原因和尋求最理想的操作參數。由於第(1)項特徵結構所處的位置設計，使絕大部分煙霧立即被排出，少部分因高溫浮力和紊流擾動而未被第(1)項特徵排出的煙霧，再由第(2)項特徵進行排出。由於排油煙機頂部第(3)、(4)、(5)項特徵結構的裝設，形成隔絕渦流，使極少部分未被第(2)項特徵排出的煙霧不易洩漏至外界。在靜態無人時，流場可視化結果顯示，若瓦斯流量Qfuel = 2.0、2.5、3.0、3.4 SLPM (瓦斯爐燃燒加熱率 q ̇fuel = 3.296、4.120、4.945、5.604 kW)，當排油煙機之吸氣槽的吸氣速度Vs ≥ 8.5、9.375、10、10.5 m/s (吸氣量Qs ≥ 6.12、6.75、7.20、7.56 CMM)，即完全無觀察到煙霧洩漏。若吸氣速度Vs小於以上所提的額定值時，可觀察到煙霧由頂板前方洩漏至外界。SF6追蹤氣體測試結果顯示：若吸氣速度大於等於額定值，在排油煙機開口面所測得的SF6時間平均洩漏濃度Cave ≤ 0.004 ppm，瞬間洩漏濃度Cmax ≤ 0.009 ppm，幾乎達到零洩漏的程度。在靜態假人站立於鍋前以及動態真人炒菜時，流場可視化結果顯示，若瓦斯流量Qfuel = 2.0、2.5、3.0、3.4 SLPM (瓦斯爐燃燒加熱率 q ̇fuel = 3.296、4.120、4.945、5.604 kW)，當排油煙機之吸氣槽的吸氣速Vs ≥ 9.75、10.375、11.5、12 m/s (吸氣量Qs ≥ 7.02、7.47、8.28、8.64 CMM)，即完全無觀察到煙霧洩漏。若吸氣速度Vs小於以上所提的額定值時，可觀察到煙霧由頂板前方洩漏至外界。SF6追蹤氣體測試結果顯示：若吸氣速度大於等於額定值，在排油煙機開口面所測得的SF6時間平均洩漏濃度Cave ≤ 0.006 ppm，瞬間洩漏濃度Cmax ≤ 0.020 ppm，幾乎達到零洩漏的程度。很明顯地，欲使雙背吸式排油煙機達到近乎零洩漏的程度，靜態假人站立於鍋前以及動態真人炒菜時的吸氣槽速度需要比靜態無人時多1~1.5 m/s。另者，相較於傳統排油煙機，雙背吸式排油煙機可以使用較少的抽風量而得到非常高的排油煙能力，且可達到近乎零洩漏。

The flow patterns and leakage levels of a dual back-suction range hood (DBS range hood) were studied experimentally. The DBS range hood consisted of five featured structures: (1) a suction slot near the pots, (2) twelve suction holes at high level, (3) one slot jets, (4) two small triangular plates on the upper left and right corners of the hood face, (5) inlet boundary-layer separation controllers (BSC). Due to the locations of structures (1) and (2), most of the oil mist was attracted and exhausted outdoors. Due to the arrangement of the structures (3), (4), and (5), outward leakage from structure (2) was isolated. Laser light-sheet assisted smoke flow visualization method was used to examine the flow patterns. Tracer gas (Sulfur Hexafluoride, SF6) detection method was applied to measure the leakage concentration of containments. For the static tests without manikine standing in front of the counter, at the propane fuel flow rate Qfuel = 2.0、2.5、3.0、3.4 SLPM (corresponding to the heating rate q ̇fuel = 3.296、4.120、4.945、5.604 kW, respectively), no oil-mist leakage was observed at the suction velocity Vs ≥ 8.5、9.375、10、10.5 m/s (suction flow rate Qs ≥ 6.12、6.75、7.20、7.56 CMM), respectively. The tracer-gas (SF6) detection experimental results corresponding to the aforementioned flow conditions revealed that the time-averaged and instantaneous leakage concentrations were Cave ≤ 0.004 and Cinst ≤ 0.009 ppm, respectively. For the static tests with a manikine standing in front of the counter and the dynamic tests with a man cooking in front of the counter, the flow visualization results showed that at the propane fuel flow rate Qfuel = 2.0、2.5、3.0、3.4 SLPM (corresponding to the heating rate q ̇fuel = 3.296、4.120、4.945、5.604 kW, respectively), no oil-mist leakage was observed at the suction velocity Vs ≥ 9.75、10.375、11.5、12 m/s (suction flow rate量Qs ≥ 7.02、7.47、8.28、8.64 CMM). Apparently, the DBS range hood presented significantly higher oil smoke removing capability than conventional range hood did. To attain almost zero leakage, the DBS range hood required significantly smaller suction velocity than the conventional range hoods did.

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