Influence of geometrical and operational parameters on the axial dispersion in an aerated channel reactor

Residence time distribution experiments have been performed on an activated sludge 3000 m³ channel reactor aerated by gas diffusion (for different liquid flowrates under constant aeration rate and constant water depth) and on a bench-scale channel reactor aerated from the bottom (for different liquid and gas flowrates and water depths) in order to characterize their hydrodynamics. Both units can be modeled as plug flow reactors with axial dispersion. A general correlation has been obtained to predict the axial dispersion coefficient as a function of the gas and liquid velocities and the geometrical parameters of the full-scale and bench-scale reactors. Finally, to facilitate the simulation of biological reactions in transient state, an equivalent model based on tanks-in-series with variable back-mixing flowrate is proposed.     

Deforestation and greenhouse gas emissions associated with fuelwood consumption of the brick making industry in Sudan

The study focuses on the role of the fired clay brick making industry (BMI) on deforestation and greenhouse gas (GHG) emissions in Sudan. The BMI is based on numerous kilns that use biomass fuel, mainly wood which is largely harvested unsustainably. This results in potential deforestation and land degradation. Fuelwood consumption data was collected using interviews and questionnaires from 25 BMI enterprises in three administrative regions, namely Khartoum, Kassala and Gezira. Annual fuelwood consumption data (t dm yr^− 1) was converted into harvested biomass (m³) using a wood density value of 0.65 t dm m^− 3. For annual GHG estimations, the methodological approach outlined by the Intergovernmental Panel on Climate Change (IPCC) was used. According to our results, the annual deforestation associated with the BMI for the whole of Sudan is 508.4 × 10³ m³ of wood biomass, including 267.6 × 10³ m³ round wood and 240.8 × 10³ m³ branches and small trees. Total GHG emissions from the Sudanese BMI are estimated at 378 028 t CO₂, 15 554 t CO, 1778 t CH₄, 442 t NO_X, 288 t NO and 12 t N₂O per annum. The combined CO₂-equivalent (global warming potential for 100-year time horizon) of the GHG emissions (excluding NO_X and NO) is 455 666 t yr^− 1. While these emissions form only a small part of Sudan's total GHG emissions, the associated deforestation and land degradation is of concern and effort should be made for greater use of sustainable forest resources and management.     

击实试验若干问题的探讨

对土的压实原理做了简单论述，介绍了在GB／T50123－1999规范中规定的击实标准及在实际工作中击实方法的选择，并对不同试验方法求得的试验结果进行了比较。同时还提出了在击实试验过程中应注意的几个问题。最后根据多年试验总结了一些经验参数。     

Study of Explosion Protection in a Small Compartment

A series of full-scale explosion suppression experiments were conducted in a compartment. The suppression performance of three extinguishing systems with two suppressants for the deflagration-type explosion was studied. The impact of agent discharge direction, the presence of an obstacle and the use of additives on suppression performance were investigated with extensive data collection and analysis. The negative aspects and toxicity issues associated with the protection systems are also addressed in the paper. The three extinguishing systems evaluated in this project were a high pressure HFC-227ea (FM-200) extinguisher, a hybrid gas generator with FM-200, and a hybrid gas generator with water, with full-system hardware including optical flame sensors and electronic controllers. The experimental results showed that the explosion in a compartment originating from a fuel spray was a serious threat to any occupant in the compartment and could cause major damage to equipment, but, the explosion generated in the experiments was controlled or extinguished by appropriate extinguishing systems.     

城市室内燃气工程有关问题的探讨

讨论了室内燃气工程中存在的有关问题及解决方法。提出了燃具前增设安全切断阀、表后采用铝塑管埋墙和燃气立管设置在楼梯间等建议。     

权重系数法全热换热器效率影响因素判定

利用权重系数建立了全热换热器的全热效率、显热效率及潜热效率三者的关系式,根据显热、潜热效率权重系数判定显热效率、潜热效率对全热换热器全热效率的影响程度。夏季工况下,我国大部分地区空调系统中全热换热器的全热效率主要受潜热效率影响。我国西北地区的空调系统不适合使用全热换热器。     

土质边坡稳定对数螺旋滑裂面的理论分析

介绍了国内外边坡稳定中的滑裂面形式，并分析了各种滑裂面形式的优缺点，在此基础上提出了一种新的滑裂面形式——对数螺旋滑裂面，对此种形式从几何构造到受力分析进行了探讨，说明了这种滑裂面形式优于其他滑裂面形式的特点。     

户式燃气空调的热力学分析

运用热力学第一定律、第二定律和能级分析理论，对户式燃气空调各种工况下的一次能源利用系数、炯效率和能级差进行分析，并与几种常用的方式进行对比。评价了户式燃气空调用能的合理性，指出了应辩证地对待户式燃气空调的发展问题。     

燃气管道不停输带气连接故障的原因和预防

分析了城市燃气管道不停输带气连接作业中常见的故障，通过对故障原因的分析找出了主要原因，并提出相应的预防措施。     

PM型成型脱硫剂的研究

ＰＭ型成型脱硫剂富硫气体脱硫剂，本文通过实验室试验、中试及沼气生产的试用，证明该脱硫剂具有净化度高，硫容大，再生易等优点，并有较适中的强度。