【作者】 高志鹰；

【导师】 孙冰；

【作者基本信息】 大连海事大学 ， 环境科学， 2013， 博士

【摘要】 液相高压脉冲放电技术采用在两个电极之间施加脉冲高压,使两电极在水中形成液相放电,放电过程同时产生强力冲击波、紫外线,各种活性自由基和强电场。前人对液相脉冲放电各种效应的研究均仅限于单方面,液相放电所产生多方面的效应还没有被综合考虑,特别是各种效应如自由基,电场,紫外线辐射,冲击波的相对贡献率,至今未得到详细的研究。本文对液相放电机理及其应用进行了详细研究,主要结论有以下几点：首先,采用针-板液相放电反应器,通过不同材料的小管将放电产生的各种效应进行了分离,深入调查了液相放电的多重效应如冲击波、紫外线,强电场和各种活性自由基的作用效果及其所占比例关系。在实验范围内,距放电点的距离(d)和峰值电压变化对紫外线杀菌所起作用基本没影响。与紫外线不同,随着距离d增加,冲击波对杀菌所起作用降低。实验范围内,峰值电压变化对冲击波杀菌作用比例几乎没有影响。距放电点的距离(d)对电场杀菌有着非常明显的影响。距离放电中心轴越远,电场对杀菌所起作用越小。放电中心轴处,紫外线、冲击波、电场对细菌杀灭所起作用近似值分别为30.8士4.8%、36.1士5.5、12.7士1.8%,由此推算出活性自由基所起作用约为20.4士2.5%。其次,设计了一个4m长管的大型水中放电装置,采用棒-棒式电极,液相中直接放电的形式,利用压力传感器测定冲击波峰值压力大小及其传播特性。冲击波在水下传播速度为1500m／s。电极间距不变,随着电压的升高,冲击波增大。在本实验范围内,经多点实验平均计算出冲击波强度经验公式为Pr=2.56E·e-0.4831r。放电电压保持不变,实验范围内当电极间距从3mm增加到7mm,冲击波峰值压力先升高后降低。峰值电流相同条件下,电极间距越大的冲击波压力值越大。主要是因为电功率对等离子体通道的击穿时间依赖于与峰值电流和通道等效电阻。电极间距增加,等离子通道的等效电阻增加。因此,电流为常量,电极间距增加,等离子体通道电功率增加。脉冲能量与冲击波峰值压力呈线性关系,能量越高,冲击波峰值压力越大。第三,液相放电能有效利用冲击波作用范围广的特点,以及紫外线和自由基有效扩散,最大限度地利用了能量,单次放电即可实现大范围的有效作用。利用液相高压脉冲放电产生的冲击波、紫外线联合作用远距离处理管道内污损生物紫贻贝,并对紫贻贝附着率及死亡率进行了调查,同时对紫贻贝的生物活性进行了监测,探讨了液相高压脉冲放电远距离处理污损生物的可行性。实验表明,提高脉冲峰值电压、增加输出能量、低频长时间、多次处理短时间对紫贻贝的去除均有较好的效果,反之则相反。同时,放电处理可以有效的降低贻贝的生物活性,且各组实验中,紫贻贝体内酶系统超氧化物歧化酶(SOD)活力与丙二醛(MDA)浓度呈负相关,过氧化氢酶(CAT)活力与过氧化氢(H2O2)浓度呈负相关,SOD趋势与CAT趋势近似。证明了液相高压脉冲放电可快速有效去除附着在远距离管道中的紫贻贝。更多还原

【Abstract】 Technology of high-voltage pulse discharge in liquid occurred in liquid between two electrodes by applying high-voltage pulse, and the process of discharging can produce strong shock waves, ultraviolet, various active, free radicals and the strong electric field. Prior research is limited to single factor of various effects of pulse discharge in liquid were, and various effects produced by discharge in liquid have not been taken into account, especially the relative contribution of free radicals, electric field, ultraviolet radiation and shock waves has not been studied in detail. In this paper, the mechanism and application of the discharge in liquid are studied in detail, and the main conclusions are as follows:First of all, various effects of needle-plate discharge in liquid are separated by the small tubes of different materials to investigation its proportion of multiple effects such as shock wave, ultraviolet radiation, strong electric field and various active free radicals generated in pulse discharge in liquid. In the experiment, the change of distance (d) apart from the discharge point and peak voltage has no effect on the radiation sterilization of the ultraviolet. Unlike ultraviolet (UV), the sterilization of the shock wave decreases when increasing of distance (d). In the experiment, the change of peak voltage has no effect on the sterilization of shock wave. The distance (d) from the discharge point has very significant effect on the sterilization of electric field. The farther the distance is apart from the central axis of discharging, the smaller the sterilization of electric field is. In the center axis of discharging, the proportion of ultraviolet radiation, shock wave, the electric field on the sterilization are approximately30.8±4.8%、36.1±5.5、12.7±1.8%respectively, thus the proportion of the active free radicals on the sterilization is calculated, and the value is about20.4±2.5%。Secondly, a large discharge device with4m-long pipe is designed, and the type of the electrode is rod-rod. The peak pressure and propagation characteristic of shock wave are measured using pressure sensor. The propagation speed of shock wave underwater is1500m/s. When the electrode gap is constant, the shock waves increase with the increasing of voltage. the shock wave intensity is calculated by averaging many values of the experiment, and the experience formula is Pr=2.56E·e-0.4831r. In the experiment, when the voltage of discharging remains constant, and the electrode gap increases from3mm to7mm, the shock wave peak increases first and then decrease. The pressure of the shock wave increases with the increasing of electrode gap, when the current peak is under the same conditions. The reason is mainly that the electrical breakdown time of plasma channel depends on the equivalent resistance of the channels and the current peak. When the electrode gap increases, the equivalent resistance of the channels is also increases. Therefore, if the current is constant, the power of plasma channel increases with the increasing of the electrode spacing. Pulse energy has a linear relation with the peak pressure of shock wave; the peak pressure of shock wave is increased when the discharge power is greater.Thirdly, discharge in liquid can effective use the advantage of shock wave and the effective diffusion of ultraviolet rays and free radicals, and the energy is used effectively. A single discharge can be effective in a wide range. The fouling organism Mytilus edulis Linnaeus which is in the pipe over a long distance is killed using the shock wave and the UV produced by the high-voltage pulse discharge in liquid, and the adhesion and mortality rates of Mytilus edulis Linnaeus were investigated. At the same time, the biological activity of Mytilus edulis Linnaeus was also monitored. The feasibility of treatment of fouling organisms using high voltage pulse discharge in liquid was also studied. The results showed that increasing the pulse voltage peak, increasing the total intput energy, low frequency and long time, many times dealing and short time had good effect on the eliminating of Mytilus edulis Linnaeus. At the same time, the discharge process can effectively reduce the biological activity of Mytilus edulis. In every group of experiment, the activity of enzyme system SOD in Mytilus edulis Linnaeus is negatively correlated with the concentration of MDA, and the activity of CAT is negatively correlated with the concentration of H2O2, and the trend of SOD is similar to that of CAT. It is proved that the high-voltage pulse discharge in liquid can be quickly and effectively on the remove of Mytilus edulis Linnaeus in the long-distance pipe.更多还原