【摘要】：生物安全柜的主要功能是提供一個潔凈的操作空間,它是微生物實驗操作的重要潔凈設(shè)備,對操作人員、試驗環(huán)境和受試樣本起隔離保護作用。三級生物安全柜提供一級,二級安全柜無法提供的絕對安全保障。所有三級生物安全柜都可在涉及一、二、三、四級生物安全水平的微生物因子實驗中使用。尤其適用于產(chǎn)生致命因子的生物試驗。但是目前三級生物安全柜在研發(fā)過程中還存在許多問題,筆者主要針對其中三個問題進行了研究。 1)三級生物安全柜是一個全密閉的負壓空間,工作人員通過手套對實驗樣本進行操作。由于內(nèi)部是負壓,一旦手套脫落,外部空氣瞬間就會進入內(nèi)部。外面未經(jīng)過濾的空氣極易造成實驗樣本的污染。假設(shè)改變回風(fēng)口格式能讓流入空氣在到達操作臺之前全部流走,就能避免實驗樣品被污染。筆者首先對這一問題進行了fluent模擬,假設(shè)壓力出口邊界條件。模擬結(jié)果是這一假設(shè)不能實現(xiàn),無論什么樣的風(fēng)口都會貫穿臺面。由于fluent模擬該問題時存在邊界條件設(shè)定的困難,假定的邊界條件模擬得出的結(jié)果不能保證其正確性。筆者制造了一個三級生物安全柜的有機玻璃模型。手套脫落后在手套口處防煙霧并記錄風(fēng)速變化。得出結(jié)論：只通過改變回風(fēng)口的方式在手套口脫落后避免樣本被污染是行不通的。假設(shè)不能實現(xiàn)。 2)三級生物安全柜需要通過傳遞窗與外界傳遞物品,當(dāng)傳遞窗打開時,操作區(qū)內(nèi)部的壓力會波動,如果內(nèi)部壓力長期處于波動狀態(tài),勢必會對實驗樣本有影響。傳遞窗打開時,首先利用傳統(tǒng)PID控制操作區(qū)內(nèi)部壓力,記錄壓力隨時間變化情況。發(fā)現(xiàn)PID控制效果不佳。而后采用基于LABVIEW編程的虛擬儀器控制風(fēng)機變頻器的頻率。在打開傳遞窗時改變風(fēng)機頻率,記錄操作區(qū)內(nèi)部壓力隨時間變化情況。實驗發(fā)現(xiàn)采用采用LABVIEW勺虛擬控制器控制效果較好,反應(yīng)速度較快。 3)孔板出流方式比格柵出流方式更適用于作為三級生物安全柜的垂直下降氣流出口,但是小孔直徑大小對氣流組織的影響是未知的。本文利用CFD模擬對孔板回風(fēng)時小孔孔徑對氣流組織的影響進行了研究。建立采用了不同孔徑孔板回風(fēng)口的三種模型。在氣流速度分別為0.2m/s及0.5m/s的情況下,利用fluent模擬回風(fēng)口孔徑為5mm,7mm,10mm,13mmm,15mm時安全柜氣流組織的情況。得到結(jié)論,在孔徑為5mm時,操作區(qū)上下部分氣流流速分割現(xiàn)象,氣流流速不均勻,氣流組織最差。綜合比較而言,采用10mm或者13mm的回風(fēng)口孔徑氣流組織較好。
[Abstract]:The main function of biosafety cabinet is to provide a clean operating space. It is an important cleaning equipment for microorganism experimental operation. Level 3 Biosafety cabinets provide one-level, two-level safety cabinets can not provide absolute security. All three-level biosafety cabinets can be used in microbiological factor tests involving level 1, 2, 3, and 4-4 biosafety. It is especially suitable for biological tests that produce lethal factors. However, there are still many problems in the research and development of three-stage biosafety cabinets. The author has mainly studied three of them. 1) the three-stage biosafety cabinet is a fully closed negative pressure space. The workers operated on the experimental samples with gloves. Because the inside is negative pressure, once the gloves fall off, the external air will enter the inside instantly. Outside unfiltered air is highly susceptible to contamination of experimental samples. It is assumed that a change in the orifice format would allow the incoming air to flow away before reaching the operating table, thus avoiding contamination of the experimental samples. At first, the author simulates this problem by fluent, and assumes the pressure outlet boundary condition. The simulation result is that this assumption cannot be realized, no matter what kind of tuyere will run through the Mesa. Due to the difficulty of setting boundary conditions when fluent simulates the problem, the results obtained by the assumed boundary conditions cannot guarantee its correctness. An organic glass model of a three-stage biosafety cabinet was made. After the glove falls off, prevent smoke at the glove mouth and record the change of wind speed. It is concluded that it is not feasible to avoid sample contamination by changing the tuyere only after the glove mouth falls off. Assuming that it cannot be realized. 2) the level III biosafety cabinet needs to deliver items to the outside world through the transfer window. When the transfer window is opened, the pressure inside the operating area will fluctuate, if the internal pressure is in a fluctuating state for a long time, It is bound to have an effect on the experimental sample. When the transfer window is opened, the traditional PID is first used to control the internal pressure of the operating area and record the pressure variation with time. It was found that the control effect of PID was not good. Then the frequency of fan frequency converter is controlled by virtual instrument based on LABVIEW programming. Change the fan frequency when opening the transfer window and record the internal pressure of the operating area with time. It is found that the virtual controller with LABVIEW scoop has better control effect and faster reaction speed. 3) the orifice outlet is more suitable than the grid outlet for the vertical downdraft outlet of the three-stage biosafety tank. However, the influence of pore diameter on airflow is unknown. In this paper, CFD simulation was used to study the effect of orifice aperture on airflow distribution. Three models with different orifice orifices were established. When the airflow velocity is 0.2m/s and 0.5m/s respectively, the airflow organization of the safety tank is simulated by fluent when the orifice aperture is 5 mm / 7 mm / 10 mm ~ 13 mm / m ~ (15 mm). It is concluded that when the aperture is 5mm, the upper and lower parts of the operating area are separated, the flow velocity is uneven and the airflow organization is the worst. In general, the air distribution of the orifice with 10mm or 13mm is better.
【學(xué)位授予單位】：東華大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2013
【分類號】：TU834

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