农业工程学报
農業工程學報
농업공정학보
2013年
13期
190-199
,共10页
程香菊%谢骏%余德光%曾映雪
程香菊%謝駿%餘德光%曾映雪
정향국%사준%여덕광%증영설
水产养殖%模型%计算%微孔曝气%氧传质%气泡-水界面%水表面
水產養殖%模型%計算%微孔曝氣%氧傳質%氣泡-水界麵%水錶麵
수산양식%모형%계산%미공폭기%양전질%기포-수계면%수표면
aquaculture%models%calculations%micro-porous aeration%oxygen transfer%air bubble-water interface%water turbulent surface
在水产养殖池塘中微孔曝气充氧系统日益受到关注,为了探究微气泡-水界面与水表面湍动对氧传质的贡献,在不同曝气流量、不同淹没水深条件下进行了水体底部微孔曝气增氧试验。基于氧体积传质理论,采用美国土木工程协会推荐的计算模型和两区氧传质模型进行耦合求解,计算得到了水体底部微孔曝气增氧过程中气泡-水界面和水表面湍动扩散氧体积传质速率。对温度修正后的体积传质速率进行分析,结果表明,在一定的淹没水深下,气泡-水界面和水表面湍动扩散氧体积传质速率均与曝气流量成正比;而在一定的流量下,气泡-水界面和水表面湍动扩散氧体积传质速率与水深成反比。针对于浅型养殖池塘,随着曝气管淹没水深的增加,虽然水表面传质的贡献率有所下降,但是其贡献仍然很大,占到了80%以上。结合微孔曝气式增氧系统具有能耗较低、安装简单等优点,采用微孔曝气式增氧系统对浅型水域增氧和湍动混合具有较大优势,值得推广采用。
在水產養殖池塘中微孔曝氣充氧繫統日益受到關註,為瞭探究微氣泡-水界麵與水錶麵湍動對氧傳質的貢獻,在不同曝氣流量、不同淹沒水深條件下進行瞭水體底部微孔曝氣增氧試驗。基于氧體積傳質理論,採用美國土木工程協會推薦的計算模型和兩區氧傳質模型進行耦閤求解,計算得到瞭水體底部微孔曝氣增氧過程中氣泡-水界麵和水錶麵湍動擴散氧體積傳質速率。對溫度脩正後的體積傳質速率進行分析,結果錶明,在一定的淹沒水深下,氣泡-水界麵和水錶麵湍動擴散氧體積傳質速率均與曝氣流量成正比;而在一定的流量下,氣泡-水界麵和水錶麵湍動擴散氧體積傳質速率與水深成反比。針對于淺型養殖池塘,隨著曝氣管淹沒水深的增加,雖然水錶麵傳質的貢獻率有所下降,但是其貢獻仍然很大,佔到瞭80%以上。結閤微孔曝氣式增氧繫統具有能耗較低、安裝簡單等優點,採用微孔曝氣式增氧繫統對淺型水域增氧和湍動混閤具有較大優勢,值得推廣採用。
재수산양식지당중미공폭기충양계통일익수도관주,위료탐구미기포-수계면여수표면단동대양전질적공헌,재불동폭기류량、불동엄몰수심조건하진행료수체저부미공폭기증양시험。기우양체적전질이론,채용미국토목공정협회추천적계산모형화량구양전질모형진행우합구해,계산득도료수체저부미공폭기증양과정중기포-수계면화수표면단동확산양체적전질속솔。대온도수정후적체적전질속솔진행분석,결과표명,재일정적엄몰수심하,기포-수계면화수표면단동확산양체적전질속솔균여폭기류량성정비;이재일정적류량하,기포-수계면화수표면단동확산양체적전질속솔여수심성반비。침대우천형양식지당,수착폭기관엄몰수심적증가,수연수표면전질적공헌솔유소하강,단시기공헌잉연흔대,점도료80%이상。결합미공폭기식증양계통구유능모교저、안장간단등우점,채용미공폭기식증양계통대천형수역증양화단동혼합구유교대우세,치득추엄채용。
Micro porous aeration systems for increasing dissolved oxygen concentration in an aquaculture pond are receiving more and more attention. In order to explore the contribution of a micro bubble-water interface and the turbulent water surface to oxygen mass transfer, after placing a disc which was made of a curled micro porous diffuser tube in the middle bottom of an experimental pond, a series of re-oxygenation experiments were conducted under the conditions of different aeration flow and submerged water depth. Based on the theory of oxygen volume mass transfer, the calculation model recommended by the American Society of Civil Engineering (ASCE) was coupled with the Two-Zone oxygen transfer model, and then the two kinds of oxygen volume mass transfer coefficients across the micro bubble-water interface and across the turbulent water surface during the re-oxygenation process in the bottom of the experimental pond were calculated. After water temperature correction, the values of oxygen volume mass transfer coefficients across the micro bubble-water interface and across the turbulent water surface were found to be in a relationship with the aeration flow and submerged water depth of micro porous diffuser tube. Under a certain submerged depth of micro-porous tube, the bubble-zone volumetric mass transfer coefficients and the surface re-aeration-zone volumetric mass transfer coefficients are proportional to the diffused airflow rate. However, under a certain diffused airflow rate, the two zone mass transfer coefficients are inversely proportional to the water depth. For shallow aquaculture ponds, with the increase of submerged water depth of micro-porous tube, though the contribution of water surface to oxygen mass transfer has been weakened a little, however, the ratio of contribution on re-oxygenation still accounts for more than 80%. Combining micro porous aeration systems has the advantage of low energy consumption and simple installation, using the micro porous diffuser system to increase dissolved oxygen concentration and water turbulent mixing in shallow water has a greater advantage, and is worth popularizing.