Comparative analysis on temperature characteristics of hydrogen-powered and traditional fossil-fueled vehicle fires in the tunnel under longitudinal ventilations

Vehicle fires in the tunnel are a great threat to the safe operation of the tunnel. Due to the rapid development of the hydrogen economy, the fire due to the hydrogen leakage could not be avoided and may bring great damage to the passengers and infrastructure. Due to the large difference between pool fires of traditional fossil-fueled and jet fires of hydrogen-powered vehicles, it is in doubt whether the existing longitudinal ventilation design could still be effective for the safety issue of hydrogen powered vehicles. To solve this problem, it is necessary to compare temperature characteristics of hydrogen-powered and traditional vehicle fires with and without longitudinal ventilations. In present work, we conducted a numerical investigation to discuss the different temperature distributions of traditional and hydrogen-fueled vehicle fires. Results indicate that the high temperature zone of the pool fire only exists above the ceiling of the vehicle. For hydrogen-powered vehicle fire, the high-speed hydrogen jet with the strong inertial force could push the hot smoke flows back to the ground. The ceiling temperature of hydrogen-powered vehicle fire is larger since hydrogen-powered vehicle has a larger heat release rate and the fire hazard of jet fires bring more danger compared with the pool fire. Although the temperature stratification is also obvious for the hydrogen-powered vehicle fire, the air temperature in the lower region could be heated and still high enough to bring a great damage to the passengers’ lives. This is quite different with the traditional pool fire. In addition, the critical ventilation velocity is also discussed. The theoretical equation could well predicted the critical ventilation velocity of traditional vehicle fires. For hydrogen-powered vehicle fires, the critical ventilation velocity could reach up to 6 m/s. The theoretical equation could not well predict the critical ventilation velocity of hydrogen-powered vehicle fires due to exist of hydrogen jet fires.     

Application of seismic attributes in structural study and fracture analysis of DQ oil field,Iran

The determination of the most unstable areas in oil fields is critical for addressing engineering problems of wellbore and sand production as well as geologic problems such as understanding dynamic constraints on hydrocarbon migration and fracture permeability. In this research work, coherency seismic attribute has been used for the determination of the most critical areas in terms of drilling stabilities in the DQ oil field, Iran. The results obtained have shown that the (1) predominant features are the SSE–NNW and N–S trends (2) the central part of the DQ structure shows the highest concentration of segment bundles, (3) the segment bundles seem to be aligned along some lineaments oriented SE–NW and SSE–NNW, and (4) on the eastern and western margins of the map there is an anomalous concentration of segments oriented E–W. It can be concluded that coherency attribute is a valuable tool for structural analysis highlighting those areas containing unstable features.     

Bulk preparation of (−)-epigallocatechin gallate-rich extract from green tea

(−)-Epigallocatechin gallate (EGCg)-rich extract (EGCg > 700 mg g⁻¹) was prepared from green tea leaves through a three-stage process consisting of liquid–liquid extraction and silica column purification. Crude tea extract was dissolved in ethyl acetate. After filtration, the solution was extracted by 10 g L⁻¹ citric acid solution twice, and then passed through silica column. The catechins compounds in the ethyl acetate eluate were back extracted to the aqueous phase, then extracted with a mixed solution of n-hexane/ethyl acetate (2/5, v/v) 3 times, concentrated, and freeze dried. 12.8 g EGCg-rich extract containing 709 mg g⁻¹ EGCg and 965 mg g⁻¹ total catechins was obtained from 300 g green tea leaves, with an EGCg recovery of 26.1% and a yield of 4.3%. This method was suitable for bulk preparation of EGCg-rich catechins from green tea leaves.     

低膦共聚物水质稳定剂的合成工艺研究

以水为溶剂,采用过硫酸铵-次磷酸盐引发体系,用马来酸酐(MA)、2-丙烯酰胺-2-甲基丙磺酸(AMPS)、丙烯酸(AA)为单体合成低膦共聚物水质稳定剂,讨论了合成温度、合成时间、单体配比以及引发剂用量等条件对产物阻垢性能的影响,确定了水质稳定剂的合成工艺。在水相中,膦酸共聚物的最佳合成温度为83~85℃,最佳合成时间为6h,最佳单体配比(MA∶AMPS∶AA)为0.50∶0.05∶0.45,过硫酸铵用量为6%、次磷酸盐相对物质的量含量为0.15时效果最佳。     

Feasibility study and performance assessment for the integration of a steam-injected gas turbine and thermal desalination system

This study proposes a systematic approach for retrofitting a steam-injection gas turbine (SIGT) with a multi-effect thermal vapor compression (METVC) desalination system. The retrofitted unit's product cost of the fresh water (RUPC) was used as a performance criterion, which comprises the thermodynamic, economic, and environmental attributes when calculating the total annual cost of the SIGT–METVC system. For the feasibility study of retrofitting the SIGT plant with the METVC desalination system, the effects of two key parameters were analyzed using response surface methodology (RSM) based on a central composite design (CCD): the steam air ratio (SR) and the temperature difference between the effects of the METVC system (?T_METVC) on the fresh water production (Q_freshwater) and the net power generation (W_net) of the SIGT–METVC system. Multi-objective optimization (MOO) which minimizes the modified total annual cost (MTAC) and maximizes the fresh water flow rate was performed to optimize the RUPC of the SIGT–METVC system. The best Pareto optimal solution showed that the SIGT–METVC system with five effects is the best one among the systems with 4–6 effects. This system under optimal operating conditions can save 21.07% and 9.54% of the RUPC, compared to the systems with four and six effects, respectively.     

Use of a selective extractant-impregnated resin for removal of Pb(II) ion from waters and wastewaters: Kinetics,equilibrium and thermodynamic study

Adsorption of Pb(II) ion by a novel extractant-impregnated resin, EIR, was studied as a function of various experimental parameters using batch adsorption experiments. The new EIR was prepared by impregnating gallocyanine (GCN) onto Amberlite XAD-16 resin beads. The EIR was characterized by nitrogen analysis and SEM micrographs. The new EIR showed excellent selectivity factor values (α) for Pb(II) adsorption respect to other metal ions. The effects of some chemical and physical variables were evaluated and the optimum conditions were found for Pb(II) removal from aqueous solutions. The equilibrium adsorption isotherm was fitted with the Langmuir adsorption model. The maximum adsorption capacity (q_max) of EIR for Pb(II) ions was found to be 367.92 mg g⁻¹. The kinetic studies showed that the intra-particle diffusion is the rate-controlling step. Also, the intra-particle diffusion coefficients, D_ip values, were of the order of 10⁻¹² m² s⁻¹. The values of enthalpy (ΔH°) were positive, which confirms the endothermic nature of adsorption process. Also, the positive entropy changes (ΔS°) were showed that the randomness increased along with the adsorption process. In addition, the obtained negative values of Gibbs free energy (ΔG°) indicated feasible and spontaneous nature of the adsorption process at different temperatures. The new adsorbent was very stable so that it can be successfully used for many consecutive cycles without significant loss in its adsorption capacity.     

论大学化学实验实施绿色化教学的可行性

化学实验实施绿色化教学是实验教学改革的重要课题,就目前化学实验产生的污染物及废液的随意排放问题,要实现绿色化学实验,减少"三废",妥善处理"三废"仍然是实验教学向绿色化迈进的主要措施,在此基础上通过实验方法、实验技术的不断改革最终实现化学实验的绿色化。     

硫铁矿制酸净化工序废酸回用的探讨

为了考察硫铁矿制酸净化工序产生的废稀酸回用于湿法磷酸萃取系统的可行性问题．将经简单沉淀和经深度处理的废稀酸分剐回用于制取磷酸。结果表明,未经深度处理的废稀酸直接回用将导致磷酸产品中砷及重金属元素铅、镉的浓度明显升高,分别升高34．13、0．22、0．50倍;废稀酸经化学沉淀法深度处理后．砷及重金属元素达到GB8978--1996《污水综合排放标准》中相关指标的要求,将其回用后所得的磷酸产品中砷及重金属元素浓度不会升高。选择合适的工艺将净化工序产生的废稀酸处理达标后再回用于湿法磷酸生产系统,能够同时取得良好的经济效益和环保效益。     

大型煤化工项目建设控制管理研究(上)

介绍了大型煤化工项目建设控制管理研究的目的和意义。以贵州开阳煤化工项目建设为研究对象,对理论条件和实际条件进行了分析。围绕项目建设"四大控制"(成本控制、进度控制、质量控制、安全控制)进行控制管理,坚持以人为本的理念,用科学的管理方法指导现场施工,加快了项目建设进程,使各单项工程一次交验合格率达到了100%。并对项目建设控制管理过程中存在的问题及经验总结进行深入分析,以期为其他大型煤化工项目建设提供借鉴和参考,避免在煤化工项目建设过程中出现类似的问题,推动和加快我国煤化工项目的建设进程。     

尿素与丙二醇合成碳酸丙烯酯的中试研究

在小试基础上,对尿素与丙二醇合成碳酸丙烯酯进行了千吨级中试研究。中试试验结果表明,在反应温度120~180℃、反应压力30~60 kPa、反应时间2~4 h、尿素与丙二醇物质的量之比1.0∶1.5、催化剂使用量为1%(质量分数)的条件下,产品碳酸丙烯酯的收率为92%~95%。在反应过程中,催化剂采用过滤的方法回收后可循环使用;反应产物经减压精馏后,产品碳酸丙烯酯的纯度为99.5%(质量分数)以上,各项质量指标均达到了优级品的要求。