Box-Behnken响应面法优化沼液氨氮削减工艺

为了确定磷酸铵镁(MAP)结晶法回收沼液中氨氮的最佳反应条件,以氨氮去除率为响应值,采用三因素三水平的Box-Behnken设计,利用响应面法研究p H值、Mg/N及P/N摩尔比对氨氮去除率的影响,建立回归模型,优化反应条件。结果表明,最优反应条件:p H值为8.38,n(Mg)/n(N)为1.32,n(P)/n(N)为1.01。对去除率影响主次顺序为p H>n(Mg)/n(N)>n(P)/n(N);p H值和n(Mg)/n(N)及p H值和n(P)/n(N)的交互作用极显著,n(Mg)/n(N)和n(P)/n(N)的交互作用显著。模型预测条件下氨氮去除率为91.61%,实际验证值为91.08%,预测值和实际值差值为0.53%,回归模型拟合较好。     

响应面法优化沼液预处理玉米秸秆条件的研究

为了确定沼液预处理玉米秸秆最优反应条件,选取沼液处理前后纤维素相对结晶度为评价指标,根据Box-Behnken试验设计原理,建立了纤维素相对结晶度与沼液用量、温度和时间之间的数学模型,并采用扫描电镜、X射线衍射法对处理前后玉米秸秆的结构特性进行分析。试验结果表明:回归方程决定系数R2为0.989 5;3个因素影响主次顺序为时间沼液用量温度,三者存在显著的交互作用;最佳处理条件为沼液用量48 m L,温度27℃,时间13 d,该条件下纤维素相对结晶度预测值为22.50%,实测值为21.88%,即沼液处理后玉米秸秆纤维素结晶度由60.82%降至47.51%,预测值与实测值相对误差为3%。沼液预处理后玉米秸秆表层被破坏,孔洞增加,有利于纤维素酶水解作用的进行。     

Box-Behnken响应面法优化粪便直接液化制取生物质油工艺条件的研究

粪便的直接液化是实现粪便无害化、减量化和资源化处理的一种新兴工艺。文章针对人粪便直接液化的工艺条件进行了探讨。以生物质油产率为指标,单因素实验结果显示,反应温度为310℃,停留时间为30min时,生物质油产率最高,为51.77%。利用Box-Benhnken响应曲面优化人粪便直接液化的工艺条件,结果显示,反应温度是影响生物质油产率的关键因素;反应温度为314℃,停留时间为43 min时,生物质油产率最高,为49.59%;生物质油热值最高可达36.59 MJ/kg。研究表明,直接液化过程是C,H元素由人粪便向生物质油中富集的过程。     

基于响应面法的全地形车排气系统结构优化研究

为了研究结构参数对全地形车排气系统散热的影响,采用Fluent软件对排气系统进行流场分析,得到壁面的温度分布图,并通过试验验证有限元模型的准确性。以消声器内隔板孔的直径、隔板到消声器前端的距离、消声器未端圆角半径为设计变量,以排气系统壁面平均温度为优化目标,应用响应面法进行结构参数优化,得到使壁面平均温度最小的一组设计变量值。最后,对改进后的排气系统进行流场分析,并与优化前的数据对比。结果表明,通过设计变量的合理改变,重点关注的消声器处壁面温度明显下降,消声器处壁面4个测试点温度分别下降了10.3%、11.5%、8.0%、10.4%。     

酸法-酶法处理麦秆木质纤维素的工艺研究

试验研究了稀硫酸常压预处理对纤维素酶水解麦秆的影响.试验结果表明:麦秆在温度为80℃、稀硫酸质量分数为4%、固液比(质量体积比,g/ml,下同)为1:25的条件下水解4h,再在温度为50℃、pH值为5.2、酶量/干物质为25 FPU/g、MgSO4/干物质为0.1 mg/g条件下水解12 h,葡萄糖得率为34.5%.经酸法-酶法处理的麦秆比未经酸处理直接酶解的麦秆的葡萄糖得率提高50%.     

稀碱法预处理对橡子壳酶水解效果的影响

首次将橡子壳作为原料,考察了碱法预处理对其化学组成变化以及纤维素酶水解得率的影响,并采用电子扫描电镜、X-射线衍射分析、红外光谱分析对橡子壳纤维结构特征进行了表征。结果表明:利用2%氢氧化钠溶液室温处理48 h时,半纤维素和木素去除率分别为29.9%和15.6%,纤维素含量达到47.0%,较处理前提高了36.2%;酶水解得率从42.8%增加至76.0%,提高了77.6%;总体葡萄糖产率达到73.5%,提高了71.7%。经过在121℃(0.15 MPa)下处理1 h,纤维素损失率较高,导致总体葡萄糖产率增幅不大。经过碱处理后,橡子壳纤维比表面积增大、表面孔洞增加,纤维结构的结晶度下降,有利于纤维素酶水解作用的进行。该试验为橡子壳酶水解工艺的进一步研究提供了依据。     

基于响应面法的煤气化工艺参数效应分析

以粉煤加压气化工艺为对象,基于ChemCAD仿真软件建立了煤气化过程仿真模型,采用中心复合设计进行了煤气化仿真试验,构建煤气化性能指标与工艺参数间的响应曲面,并在此基础上对煤气化各工艺参数对气化性能的主效应和交互效应进行了分析.结果表明：氧煤质量比是影响煤气化性能最重要的工艺参数,氧煤质量比的增加能提高煤气中CO体积分数、产气率和碳转化率,但会降低H2体积分数;蒸汽煤质量比主要影响煤气的有效气体成分,H2体积分数随其值提高而显著增加,CO体积分数下降;蒸汽煤质量比对产气率和碳转化率影响较小;压力对煤气中有效气体成分、产气率和碳转化率影响均不显著;氧煤质量比、蒸汽煤质量比和压力的综合效应对煤气中有效气体成分影响不显著,但对产气率和碳转化率等生产效率指标影响显著.     

基于响应曲面法的涡轮增压器废气阀门激光焊接工艺优化研究

激光焊接技术凭借其高效、高精度的特点已广泛应用在汽车制造产业,在涡轮增压器的生产中,激光焊接也逐步被应用于实现废气阀门与阀杆的连接。虽然当前对于激光焊接的工艺研究很多,但对工艺参数的优化也一直缺少一个科学有效的方法。本文以熔接深度、熔接宽度和内部缺陷作为响应变量,选取焊接功率、焊接速度作为因子,运用响应曲面法(RSM)设计实验方案,通过对响应结果进行分析,研究焊接参数对焊接质量的影响,拟合能够预测最优参数的数学模型,最终将获得的最优参数运用到生产中进行验证。     

基于响应面法的圆盘泵叶轮优化研究

为了提高圆盘泵的水力性能,以径向直叶片圆盘泵为研究对象,结合计算流体动力学方法(CFD)与响应面分析法,研究叶轮结构参数对泵扬程和效率的影响.以叶片高度、叶片数量和盘间距为优化设计变量,泵的扬程和效率为响应变量,基于Box-Behnken样本点设计法进行三因素三水平设计,建立17组样本点.通过ANSYS CFX数值计算...     

Optimizing thermomechanical pretreatment conditions to enhance enzymatic hydrolysis of wheat straw by response surface methodology

Wheat straw was pretreated with a thermomechanical process developed in our laboratory to improve the enzymatic hydrolysis extent of potentially fermentable sugars. This process involves subjecting the lignocellulosic biomass for a short time to saturated steam pressure, followed by an instantaneous decompression to vacuum at 5 kPa. Increasing of the heat induced by saturated steam result in intensive vapour formation in the capillary porous structure of the plant material and the subsequent release of the pressure to vacuum allows fixing the expanded structure. Response surface methodology (RSM) based on central composite design was used to optimize three independent variables of the pretreatment process: processing pressure (300-700 kPa), initial moisture contents of wheat straw (10-40%) and processing time (3-62 min). The process was optimised for hydrolysis yield and initial hydrolysis rate obtained by enzymatic hydrolysis on the pretreated solids by Celluclast (1.5 L). The analysis of variance (ANOVA) revealed that, among the process variables, processing pressure and processing time have the most significant effect on the hydrolysis yield and on initial rate of hydrolysis whereas initial moisture content observed significantly lower effect on the two responses. The predicted hydrolysis yield and in a lesser extent the predicted initial rate of hydrolysis agreed satisfactorily with the experimental values with R² of 96% and 86% respectively.     

Optimization of fermentative hydrogen production process by response surface methodology

The effect of temperature, initial pH and glucose concentration on fermentative hydrogen production by mixed cultures was investigated in batch tests, and the optimization of fermentative hydrogen production process was conducted by response surface methodology with a central composite design. Experimental results showed that temperatures, initial pH and glucose concentrations had impact on fermentative hydrogen production individually and interactively. The maximum hydrogen yield of 289.8 mL/g glucose was estimated at the temperature of 38.6 °C, the initial pH of 7.2 and the glucose concentration of 23.9 g/L. The maximum hydrogen production rate of 28.2 mL/h was estimated at the temperature of 37.8 °C, the initial pH of 7.2 and the glucose concentration of 27.6 g/L. The maximum substrate degradation efficiency of 96.9% was estimated at the temperature of 39.3 °C, the initial pH of 7.0 and the glucose concentration of 26.8 g/L. Response surface methodology was a better method to optimize the fermentative hydrogen production process. Modified logistic model could describe the progress of cumulative hydrogen production in the batch tests of this study successfully.     

响应面法优化稻壳微波裂解工艺研究

生物质能源是近年来逐渐兴起的可再生能源,有望替代传统化石能源,成为未来人类利用的主要能源之一,受到越来越广泛的关注。以稻壳为原料,通过微波快速裂解技术制备可再生的生物油,为充分利用废弃物制备可再生能源提供新的途径。通过Box-Behnken中心组合试验设计,优化出制备生物油产率最高的工艺参数:裂解温度为627.81℃、微波功率为1.9 kW、吸收剂添加量为3.27%、裂解时间为5.52 min,生物质油得率的预测值为35.87%。     

Evaluation and optimization of organosolv pretreatment using combined severity factors and response surface methodology

In this study, ethanol organosolv pretreatment was investigated and optimized for the pretreatment of empty palm fruit bunch using (1) response surface methodology based on three-variable central composite design and (2) the combined severity parameters. The reaction parameters studied were sulfuric acid concentration (0.5–2.0%), reaction temperature (160–200 °C) and residence time (45–90 min). Both models provide valuable and complementary informations: using combined severity parameters, very good predictions were obtained concerning xylan and lignin extraction whereas central composite design is the best model for glucose production. The optimal values of the variables were as the followings: sulfuric acid 2.0% w/w, 160 °C, 78 min and the experimental values (96.0%) concerning glucose and lignin recovery were in excellent agreement with the central composite design prediction (100%).     

响应曲面法优化固体碱催化制备生物柴油的工艺

以固体碱硅酸钠为催化剂进行酯交换反应制备生物柴油,采用响应曲面法中的Box-Behnken模式对影响生物柴油转化率的4个主要因素(温度、催化剂用量、反应时间、醇油物质的量比)进行优化.建立生物柴油转化率的二次多项回归模型方程,并对回归方程系数进行显著性检验和方差分析.试验结果表明:当反应温度为66℃、催化剂用量为大豆油质量的2.1%、反应时间为7h、醇油物质的量比为8.6:1时,生物柴油的转化率最高,最高转化率预测值为75.78%,与实测值基本相符,优化模型有效可靠.     

基于响应面法对秸秆纤维素乙醇生产工艺参数的优化

文章在对里氏木霉T12菌株产纤维素酶的培养条件进行单因素优化的基础上,以滤纸酶活力(FPA)为响应值,通过Plackett-Burman设计法筛选出对产酶影响最显著的3个因素,依次为麦麸>温度>氯化钙。响应面优化结果为当麦麸、温度、氯化钙分别为6.27 g/L,31℃,0.709 g/L时,纤维素酶理论最大FPA酶活为62281.3 U/m L。在优化后的培养条件下纤维素酶粗酶液的实际FPA酶活为60 126.5±16.0 U/m L。将纤维素酶粗酶液以10%添加量加入秸秆一步转化乙醇的5 L发酵罐中,经过144 h的发酵,乙醇产量(v/v)可达到7.05%±0.18%。     

Application of an electric field for pretreatment of a feedstock (Laminaria japonica) for dark fermentative hydrogen production

When using cellulosic biomass as feedstock for dark fermentative hydrogen production (DFHP), feedstock preparation is essential step for enhancement of biodegradability. In the present work, electric field was newly applied as a novel pretreatment technique to Laminaria japonica, a marine brown algae, as an alternative method for feedstock preparation. A feasibility test was first conducted (20–100 V for 30 min). The highest H₂ yield (93.6 mL H₂ g⁻¹ dry cell weight (dcw)) was achieved at applied voltage of 60 V, while the performance was decreased from applied voltage of 80–100 V due to increasing formation of hydroxymethylfurfural. Subsequently, electric pretreatment conditions (applied voltage and reaction time) were statistically optimized, and a H₂ yield of 102.7 mL g⁻¹ dcw was recorded with applied voltage 58.5 V and reaction time 30 min. This was 96.1% of the predicted value. These findings clearly revealed that the application of electric field as pretreatment method has enormous potential as an alternative method for feedstock preparation in DFHP.     

Fermentative hydrogen production from macroalgae Laminaria japonica pretreated by microwave irradiation

Pretreatment is an essential procedure to enhance the biodegradability when algae biomass is used as substrate for fermentative hydrogen production, In this study the potential of microwave pretreatment for enhancing the hydrogen production from macroalgae biomass Laminaria japonica was investigated. Microwave pretreatment at different temperatures (100–180 °C, 30 min) was explored, algae biomass disruption increased with increasing temperature, while highest hydrogen yield of 15.8 mL/g TS_added was obtained from 160 °C microwave treated algae biomass. Hydrogen production can be indicated by the dehydrogenase activity. After the microwave treatment, hydrogen production process altered from butyrate-type to acetate-type fermentation. Maximum hydrogen yield was enhanced by 1.9 fold compared with the control test. Indicating microwave treatment can be a good candidate in enhancing the hydrogen production from macroalgae biomass.     

Study on optimization of co-digestion process parameters for enhancing biohydrogen production using response surface methodology

In the present study, batch anaerobic co-digestion experiment was conducted with dairy secondary clarifier waste activated sludge as substrate and anaerobic digested municipal waste activated sludge as seed sludge for enhancing biohydrogen rate. The statistical tools were used to study the effect of co-digestion process parameters (pH, seed sludge, temperature, and digestion time) on mixed liquor suspended soils (MLSS) reduction % and chemical oxygen demand (COD) solubilization %. The maximum of MLSS reduction and COD solubilization obtained at global optimal condition (pH 6, temperature 40°C, seed sludge 35 ml, and digestion time 30 days) determined, respectively, were 22.7 and 28.02%. Subsequently, the production data of cumulative biohydrogen were fitted with modified Gompertz equation and the biohydrogen kinetic parameters were determined.