本文選題：電解水制氫 + 氣液兩相流�。� 參考：《重慶大學(xué)》2016年博士論文

【摘要】：氫氣以其來源廣泛、清潔燃燒、能量密度高等突出優(yōu)點(diǎn)成為最有潛力的清潔能源之一,也是重要的食品化工原料。雖然目前水電解制氫在所有制氫手段中所占的比例并不高,但電解水制氫是目前不可替代的超純氫來源和分布式能源構(gòu)成部分,未來有著光明前景。采用電解水制氫還可以作為中間媒介,有效整合風(fēng)能、太陽能等時(shí)域和地域性強(qiáng)的清潔能源構(gòu)建持續(xù)清潔能源供應(yīng)系統(tǒng),實(shí)現(xiàn)氫能的更廣泛應(yīng)用。在如超大規(guī)模集成電路制造和浮法玻璃生產(chǎn)等行業(yè)中,與其他制氫方法相比,通過水電解制取高純氫是一些工業(yè)用氫必要的制氫手段。電解過程的高能耗是制約水電解制氫發(fā)展的瓶頸,電解水產(chǎn)生1 Nm3氫氣能耗為4.5~5.0 k Wh,效率在60%以下,因此如何強(qiáng)化水電解制氫,提高其電解效率非常必要。在水電解過程中,氣相產(chǎn)物的管理是一項(xiàng)重要的工作。及時(shí)排除電極表面氣相產(chǎn)物有利于電解槽能耗的降低�，F(xiàn)有工業(yè)電解槽中主要依靠循環(huán)泵驅(qū)動(dòng)電解液流動(dòng)來排出氣相產(chǎn)物。有報(bào)道表明,在磁場作用下,電解液中存在洛倫茲力引發(fā)的多尺度對(duì)流,利用磁場可驅(qū)散氣相產(chǎn)物。但磁場在有氣相存在條件下作用在電解質(zhì)的機(jī)制還不清楚,如何強(qiáng)化這個(gè)磁場作用來達(dá)到提升電解效率還亟待研究。為分析磁場對(duì)水電解過程的影響及作用機(jī)制,本文在理論分析的基礎(chǔ)上,通過實(shí)驗(yàn)和數(shù)值模擬相結(jié)合的方法,重點(diǎn)針對(duì)電極表面的氣泡行為及磁場驅(qū)動(dòng)下電極間的氣液兩相流動(dòng)進(jìn)行分析,主要包含以下幾個(gè)方面的內(nèi)容:1、通過數(shù)值模擬,基于Fluent計(jì)算平臺(tái),采用VOF(volume of fluid)模型對(duì)電極表面的析氫過程進(jìn)行模擬。根據(jù)法拉第定律計(jì)算電極表面的氫組分的生成速率,建立了基于過飽和氫組分質(zhì)量傳遞的氣泡生長模型,通過UDF(user define function)接口編譯到計(jì)算模型中,并進(jìn)行了實(shí)驗(yàn)驗(yàn)證。研究還發(fā)現(xiàn),在氣泡成核與生長階段,電極表面存在多種形式的對(duì)流作用,包括電解液中由于氫組分濃度梯度引發(fā)的對(duì)流和由于氣泡界面擴(kuò)張引發(fā)的電解液擾動(dòng)。通過對(duì)不同對(duì)流形式下電極表面?zhèn)髻|(zhì)系數(shù)的計(jì)算,量化了單氣泡演化過程對(duì)于局部傳質(zhì)的強(qiáng)化效果。2、在分析電極表面氫氣泡演化過程的基礎(chǔ)上,采用微電極和常規(guī)尺寸的局部疏水電極實(shí)驗(yàn)分析了外部磁場對(duì)于電極表面氣泡行為的影響。在微電極表面,通過高速攝像記錄了氣泡的生長過程,給出了氣泡生長曲線和磁場對(duì)于氣泡生長的影響。分析了不同電流條件下,電極表面氫組分過飽和濃度的變化。采用光刻—電沉積的方法制作了局部疏水電極,并實(shí)驗(yàn)觀測了氣泡在局部疏水位置的生長和脫離行為特性。分析了導(dǎo)致疏水點(diǎn)處大氣泡隨機(jī)脫離的原因。對(duì)比磁場作用下微電極和常規(guī)尺寸電極表面氣泡脫離行為的差別,并通過數(shù)值模擬的方法揭示了因micro-MHD流動(dòng)使氫氣泡周圍壓力分布變化而導(dǎo)致氣泡行為改變的磁場作用微觀機(jī)制。3、采用平行光亮鉑電極,測試了磁場對(duì)電解槽電勢差的影響。同時(shí),基于Fluent計(jì)算平臺(tái),采用Euler-Euler模型,對(duì)磁場驅(qū)動(dòng)下電極間的電解液流動(dòng)方式和氣相產(chǎn)物的分布規(guī)律進(jìn)行了分析,揭示了因MHD驅(qū)動(dòng)減小了電極間氣相產(chǎn)物份額和電極表面氣相覆蓋度的磁對(duì)流影響電極電勢差的物理機(jī)制。
[Abstract]:Hydrogen is one of the most potential clean energy sources with its wide source, clean combustion and high energy density. It is also an important raw material for food and chemical industry. Although the proportion of hydrogen production in all hydrogen making means is not high at present, hydrogen production by electrolysis is an irreplaceable source of ultra pure hydrogen and a distributed source of energy. The future has a bright future. The use of electrolysis water to produce hydrogen can also be used as intermediate medium, effective integration of wind energy, solar energy and other time-domain and regional strong clean energy to build a continuous clean energy supply system to achieve a more extensive application of hydrogen energy. In such industries as large scale integrated circuit manufacturing and float glass production, and other systems Compared with hydrogen, making high pure hydrogen by water electrolysis is a necessary means of hydrogen production for industrial hydrogen. The high energy consumption of electrolysis process is the bottleneck restricting the development of hydrogen production by electrolysis. The energy consumption of 1 Nm3 hydrogen is 4.5~5.0 K Wh and the efficiency is below 60%. Therefore, it is necessary to strengthen the water electrolysis and improve the efficiency of electrolysis. In the process of solution, the management of gas phase products is an important work. Eliminating the gas phase products on the surface of the electrode in time is beneficial to the reduction of the energy consumption of the electrolyzer. The existing industrial electrolysis cell mainly relies on the circulation pump to drive the electrolyte flow to expel the gas phase products. It is reported that under the effect of the magnetic field, there are many feet caused by Lorenz force in the electrolyte. It is not clear that the mechanism of the magnetic field acting on the electrolyte under the presence of gas is not clear. How to strengthen the effect of this magnetic field to improve the electrolysis efficiency is still urgently needed to be studied. The method combined with numerical simulation focuses on the bubble behavior on the surface of the electrode and the analysis of gas-liquid two phase flow between the electrodes driven by the magnetic field. The main contents are as follows: 1, the hydrogen evolution process on the electrode surface is simulated by the VOF (volume of fluid) model by numerical simulation and based on the Fluent computing platform. According to Faraday's law, the formation rate of hydrogen components on the surface of the electrode is calculated. A bubble growth model based on the mass transfer of the supersaturated hydrogen component is established. The model is compiled into the calculation model by UDF (user define function) interface, and the experimental verification is carried out. Convection, including the convection caused by the concentration gradient of the hydrogen component in the electrolyte and the electrolyte disturbance caused by the expansion of the bubble interface. By calculating the mass transfer coefficient of the electrode surface under different convection forms, the enhanced effect of the single bubble evolution process for local mass transfer was quantified, and the evolution process of hydrogen bubbles on the surface of the electrode was analyzed. On the basis of the microelectrode and the conventional size local hydrophobic electrode, the effect of the external magnetic field on the bubble behavior on the surface of the electrode was analyzed. The growth process of the bubble was recorded on the microelectrode surface by a high-speed camera. The bubble growth curve and the influence of the magnetic field on the growth of the bubble were given. A local hydrophobic electrode was made by photolithography and electrodeposition, and the growth and disengagement behavior of the bubbles in the local hydrophobic position were observed. The reasons for the random separation of the large bubbles at the hydrophobic point were analyzed. The surface gas of the microelectrode and the conventional electrode was compared with the magnetic field. The difference in bubble separation behavior was obtained by numerical simulation, and the micromechanism.3 of the magnetic field action caused by the change of the pressure distribution around the hydrogen bubble caused by the micro-MHD flow was revealed. The effect of the magnetic field on the potential difference of the electrolyzer was tested by the parallel bright platinum electrode. At the same time, the Fluent calculation platform was used for Euler-Euler. The model, the flow mode of electrolyte between the electrodes driven by the magnetic field and the distribution of the gas phase products are analyzed. The physical mechanism of the influence of the magnetic convection on the potential difference between the gas phase and the surface gas coverage of the electrode has been revealed by the MHD drive.
【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：TQ116.21

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