3D打印微生物燃料电池阳极及其性能特性

微生物燃料电池是一种处理废水同时产生电能的新型装置,阳极作为微生物燃料电池的重要组件极大地影响电池性能。针对微生物燃料电池传统三维电极结构不合理导致电极内部物质传输受限,电池功率密度较低的问题,本文采用3D打印技术并碳化的方式构建了结构可控的微生物燃料电池阳极,通过热重分析得到合适的碳化条件,并通过进一步的电化学分析和电极微观形貌拍摄研究了电极内部孔道结构对微生物生长情况和电池性能的影响。实验结果表明：电极孔径尺寸为0.4mm时,电池具有最优性能,其最大功率密度达12.85W/m²,比采用碳布阳极的MFC提升10倍,较采用碳毡阳极的燃料电池高38%;具有可控孔道结构电极的传荷阻抗和传质阻抗是限制电极性能的主要因素,通过优化孔道尺寸和结构分布可降低其传荷及传质阻抗,可以进一步提升电池性能。     

微生物燃料电池中阴极长期运行的性能分析

微生物燃料电池（MFC）阴极性能在长期运行过程中逐渐下降,查明其下降原因对MFC技术的实际应用具有重要意义。采用泡沫镍阴极研究了阴极长期运行过程中阴极下降的原因。研究发现：MFC运行4个月之后功率密度相比运行1周的MFC下降达22%,测试电极极化曲线发现阴极性能的下降是导致MFC功率密度下降的主要因素。线性伏安扫描（LSV）结果显示：运行初期在-0.2 V电势下阴极电流密度为12.3 A·m^-2,而运行4个月后,阴极电流密度下降为4.2 A·m^-2,阴极性能随运行时间增加而降低主要表现在大电流区域[>-0.05 V （vs Ag/AgCl）]。对阴极表面和内部进行扫描电子电镜（SEM）分析发现：阴极表面没有明显的生物膜,氧扩散实验发现阴极氧扩散量明显降低是造成阴极性能下降的主要原因;通过能谱分析（EDS）可知阴极内部有磷酸盐析出。这些结果说明阴极内部在长期运行过程中逐渐析盐,而析盐导致泡沫镍阴极内孔隙堵塞,阻碍氧扩散到催化层,从而使阴极性能降低。     

Coupling of mixing and microbial kinetics for evaluating the performance of bioreactors

The effect of the dynamics of the mixing process in mechanically stirred bioreactors upon their performance has been investigated by using a circulation-model for flow of fluid and a two-environment-model to account for the extent of micromixing in the vessel. With the help of an empirical kinetic model to depict the oxidative and the fermentative growth of bakers' yeast, experimentally observed effects of initial sugar concentrations upon critical dilution rates in continuous cultures of this system could be explained. Effect of different scales of operation upon productivities of fed-batch cultures of bakers' yeast could also be satisfactorily predicted. A discrete simulation procedure was found to be a convenient tool in coupling the two-environment circulation-model of mixing with kinetics of microbial reactions.     

微生物燃料电池的动态性能分析及其神经网络预测控制

微生物燃料电池（microbial fuel cell,MFC）反应底物浓度的控制问题是整个系统优化控制的重要环节,其控制效果的优劣对系统的输出电压有很大的影响。针对MFC输出电压在常规控制策略下超调量大和响应速度慢的特点,对MFC系统模型中输入量、控制量的变化对系统输出的影响进行动态仿真;将负载电流作为扰动量,提出了针对MFC系统阳极进料流量进行控制的神经网络预测控制策略。仿真结果表明,与PID控制方法相对比,利用神经网络预测控制策略的系统输出电压响应速度快且超调量小,其动态性能得到了较大的改善。     

Effect of temperature on the performance of microbial fuel cells

Single and double chamber microbial fuel cells (MFCs) were tested in batch mode at different temperatures ranging from 4 to 35 °C; results were analysed in terms of efficiency in soluble organic matter removal and capability of energy generation. Brewery wastewater diluted in domestic wastewater (initial soluble chemical oxygen demand of 1200 and 492 mg L⁻¹ of volatile suspended solids) was the source of carbon and inoculum for the experiments. Control reactors (sealed container with support for biofilm formation) as well as baseline reactors (sealed container with no support) were run in parallel to the MFCs at each temperature to assess the differences between water treatment including electrochemical processes and conventional anaerobic digestion (in the presence of a biofilm, or by planktonic cells). MFCs showed improvements regarding rate and extent of COD removal in comparison to control and baseline reactors at low temperatures (4, 8 and 15 °C), whilst differences became negligible at higher temperatures (20, 25, 30 and 35 °C). Temperature was a crucial factor in the yield of MFCs both, for COD removal and electricity production, with results that ranged from 58% final COD removal and maximum power of 15.1 mW m⁻³ reactor (8.1 mW m⁻² cathode) during polarization at 4 °C, to 94% final COD removal and maximum power of 174.0 mW m⁻³ reactor (92.8 mW m⁻² cathode) at 35 °C for single chamber MFCs with carbon cloth-based cathodes. Bioelectrochemical processes in these MFCs were found to have a temperature coefficient, Q10 of 1.6.A membrane-based cathode configuration was tested and gave promising results at 4 °C, where a maximum power output of 294.6 mW m⁻³ reactor (98.1 mW m⁻² cathode) was obtained during polarization and a maximum Coulombic efficiency (Y_Q) of 25% was achieved. This exceeded the performance at 35 °C with cloth-based cathodes (174.0 mW m⁻³; Y_Q 1.76%).     

碳纤维阳极构造对微生物燃料电池性能的影响

微生物燃料电池（MFCs）阳极性能受生物膜的影响,而生物膜则直接与阳极表面积有关。以不同长度和数量的碳纤维丝作为阳极,研究了阳极构造和表面积对MFC输出功率的影响。当阳极为单根长度为1 cm碳纤维丝时,MFC产生的最大功率密度最高,为10.50 W·m^-2,随着碳纤维丝长度逐渐增加（2～14 cm）,MFC产生的最大功率显著下降。以多根的长度为2 cm碳纤维丝构成阳极时,MFC的功率与根数（1～4 根）呈正比,当采用4根2 cm纤维丝时,MFC的最大功率密度为2.92 W·m^-2,该数值为单根8 cm碳纤维丝的2.78倍。观察碳纤维丝长度方向上的生物膜的分布表明：受碳纤维欧姆电阻的影响,在碳纤维丝电流引出端附近的生物量明显大于碳纤维其他地方,这说明：增加纤维丝长度虽可提高阳极的表面积,但并不能提高阳极的产电性能。     

Energy requirements and economic analysis of a full-scale microbial flocculation system for microalgal harvesting

Certain strains of microalgae have high lipid yields and appear to be good choices for the production of biodiesel, however, one of the major difficulties is the lack of a large-scale cost effective harvesting technique. Microbial flocculation has the potential to provide a solution without the use of contaminating metallic ions such as Al³⁺. However, such flocculation would require the mixing of mega- or even giga-litres of microalgal culture on a daily basis and therefore it is important to estimate the energy required. By incorporating a baffled hydraulic flocculator into a proposed large scale system that was designed on the basis of laboratory data, the mixing energy required for the flocculation is estimated to be equivalent to 0.893 kWh per 10³ kg of dry mass flocculated, the overall cost of the process is A$ 0.13 m⁻³ of the culture medium and the net footprint area of the flocculating system is 0.7% of the proposed 1 km² high rate algal pond.     

Energy system diagnosis of paper-drying process,Part 1: Energy performance assessment

Paper drying is a highly energy-intensive and complicated multivariate process. The dryer section plays an important role in the energy consumption of a paper machine, especially of thermal energy. A comprehensive method for assessing the energy performance of the dryer section was investigated in this study to improve energy efficiency. This method was divided into three component processes: energy and evaporation load audit, field test and observation, and energy flow analysis and energy efficiency estimation. In a case study, we found that the method could, in addition to analyzing the key factors that restrict drying efficiency, also depict the details of energy consumption clearly. At the same time, several significant energy-saving measures were suggested to improve the energy efficiency of the paper-drying process.     

Energy harvesting performance of viscoelastic polyacrylic dielectric elastomers

Viscoelasticity dissipates the mechanical energy, leading to a reduction of energy conversion efficiency in both dielectric elastomer (DE) actuators and generators. By measuring the uniaxial tension-recovery experiments of very-high-bond-based DE, this article quantitatively presents the effect of viscoelasticity on energy harvesting performance of DE generators. By employing a DE strip energy harvester with constant surface charge, an analytical model is established to calculate the generated electrical energy and energy conversion efficiency. Numerical results demonstrate that viscoelasticity has a significant influence on DE energy harvesting performance.     

阳极双电层电容对微生物燃料电池性能的影响

采用3种活性炭粉制备具有不同电容的阳极,研究了双电层电容阳极对单室空气阴极微生物燃料电池启动、运行、性能、阳极生物膜附着的影响。结果表明:当电极表面积相近的情况下,阳极双电层电容从0.0012 F增加到22.72 F时,微生物燃料电池启动时间缩短了68.0%,电池的最大功率密度增加了16.8倍,达到546.1 m W·m-2。扫描电子显微镜的结果表明高电容的阳极表面附着的微生物量比低电容电极的高1倍。因此,微生物燃料电池性能受阳极双电层电容的影响,而与阳极表面积的相关性小。     

循环伏安扫描对微生物燃料电池启动和产电性能的影响

微生物燃料电池（MFCs）的启动及产电性能直接影响其应用于对实际废水的处理。以屠宰厂废水为基质研究了循环伏安扫描对单室空气阴极微生物燃料电池启动和产电性能的影响。结果表明：经过24 h CV扫描的MFCs其启动时间比常规电阻（1000 Ω）直接启动的MFCs缩短了71.4%（从420 h缩短至120 h）,MFCs最大功率密度提高了21.5%,达到37.8 W·m^-3。通过电极生物量测定和生物膜表面形貌观察发现,经CV扫描的阳极生物量显著提高且生物膜的产电菌占优势是MFCs性能提高的主要原因。说明CV扫描不断促进产电菌在阳极表面的吸附,而且增加产电微生物的生长速度。这一技术为发展MFCs的快速启动和提升MFCs的产电性能提供了新思路。     

活性炭空气阴极微生物燃料电池的放大和串并联组合研究

采用体积分别为28 mL(mL-MFC)和4.5 L(L-MFC)的单室空气阴极微生物燃料电池,考察了扩大化对活性炭空气阴极性能的影响.mL-MFC的最大功率密度为30 W/m3(1 200 mW/m2),L-MFC的最大功率密度为7.3 W/m3 (435 mW/m2),扩大化后活性炭空气阴极性能下降是致使L-MFC功率降低的主要原因.电化学阻抗(EIS)分析表明,L-MFC中阴极性能下降主要是由于工作水压增大,导致了阴极扩散电阻增大和氧气还原速率降低.通过串联或并联方式组合L-MFC,可明显提高电池的输出电压或电流;串并联组合后电池的功率密度有所下降,主要由电池连接时的接触电阻引起.     

Improvement of sediment microbial fuel cell performance by application of sun light and biocathode

Three series of experiments were conducted to improve sediment microbial fuel cell (SMFC) performance. At first, dissolved oxygen level of catholyte was increased with native seaweed of the Caspian Sea. Power output was improved about 2-fold, and maximum power density of 46.14 8mW/m² was produced in the presence of seaweed as biocathode in cathode compartment. Secondly, the best depth to embed anode was then determined. Anode was embedded in 3, 6, 9 and 12 cm below the sediment/water interface. The best depth to bury the anode was finally determined in 3 cm below the sediment/water interface, maximum generated power and current density of 42.156 mW/m² and 282.92 mA/m², were respectively obtained in this depth. In addition, influence of agitated flow on power generation from SMFC was investigated.     

阳极进水COD浓度对三室空气阴极微生物脱盐燃料电池性能的影响

以厌氧污泥为接种微生物构建三室空气阴极微生物脱盐燃料电池,研究阳极进水COD浓度对微生物脱盐燃料电池产电及脱盐性能的影响。结果表明,阳极进水COD浓度为800 mg/L,12 h后降解至100 mg/L以下,当在100～800 mg/L变化时,阳极出水COD浓度随进水COD浓度增加而增加,平均电压随进水COD浓度先上升后下降,脱盐率随进水COD浓度先增加后趋于平缓。阳极适量进水COD浓度有利于提高微生物脱盐燃料电池产电脱盐效率,研究结果为进一步优化微生物脱盐燃料电池反应器运行提供了参考。     

阳极进水COD浓度对三室空气阴极微生物脱盐燃料电池性能的影响

以厌氧污泥为接种微生物构建三室空气阴极微生物脱盐燃料电池,研究阳极进水COD浓度对微生物脱盐燃料电池产电及脱盐性能的影响。结果表明,阳极进水COD浓度为800 mg/L,12 h后降解至100 mg/L以下,当在100～800 mg/L变化时,阳极出水COD浓度随进水COD浓度增加而增加,平均电压随进水COD浓度先上升后下降,脱盐率随进水COD浓度先增加后趋于平缓。阳极适量进水COD浓度有利于提高微生物脱盐燃料电池产电脱盐效率,研究结果为进一步优化微生物脱盐燃料电池反应器运行提供了参考。     

Air-breathing microbial fuel cell with enhanced performance using nanocomposite proton exchange membranes

This work aims to improve the performance of air-breathing microbial fuel cells (MFCs) through using hydrocarbon polymer based nanocomposite proton exchange membranes. Accordingly, nanocomposite membranes based on sulfonated poly(ether ether ketone) (SPEEK) and montmorillonite (MMT) were investigated for such an application. Although the incorporation of MMT into SPEEK membranes resulted in reduced oxygen permeability as well as proton conductivity, but the overall selectivity was found to be improved. MFC tests revealed that using the optimized nanocomposite membrane (SPEEK-70/MMT-3 wt%) results in a considerably higher open circuit voltage (OCV) compared to the corresponding neat membrane. Moreover, it was found that the SPEEK-70/MMT-3 wt% membrane is able to provide about 40% more power output than Nafion^®117. On the account of high proton conductivity, low oxygen permeability, high electrochemical performance, ease of preparation and low cost, hydrocarbon based nanocomposite PEMs could be considered as promising electrolytes to enhance the performance of MFCs.     

基于Citect SCADA能源绩效系统的设计与实现

采用Citect SCADA信息技术作为平台,对公司A类指标、成本核算及考核与奖励进行进行了设计和配置,实现以实际数据来反映生产的具体情况,从而反映车间级别KPI相关数据,为操作者和管理者提供运行和考评决策支持,提高生产效率。