Formation and O2/CO2 combustion characteristics of real-environment coal char in high-temperature oxy-fuel conditions

Oxygen-fuel combustion is a promising technology for CO₂ emission reduction. The high-temperature entrained flow reactor and high-temperature drop tube furnace were used to analyses the formation and O₂/CO₂ combustion characteristics of real-environment coal char in high-temperature oxy-fuel conditions. It proposed “inflection point standard” of high-temperature flame method for the preparation of real-environmental oxy-fuel coal char according to the flame method. The results show that the ratios of C=O/C-O and C=O/C_ar increase in the coal char compared with the raw coals. The trend of C=O/C_ar in oxy-fuel condition is opposite to that in the inert atmosphere, due to the effect of high-concentration CO₂. To achieve the burnout rate similar to air combustion for coal char, with the increase of coal rank, the O₂ concentration should be enhanced. The optimal O₂ concentration for the oxy-fuel combustion of JC anthracite is 30%, while that of other low-rank coals could be lower than 30%. The combustion characteristic of JC anthracite is with the highest sensitivity to temperature and O₂ concentration.     

Precision manufacturing of turbine wheel slots by trim-offset approach of WEDM

The present study aims to precisely manufacture the turbine wheel slot using a novel trim-offset approach of wire-electrical-discharge-machining (WEDM) in order to overcome the challenges of a conventional broaching process. Two dimensional model of turbine wheel slot is prepared in ‘ELCAM’ software to generate the computer-numerical-control (CNC) code of fir-tree-profile geometry. The experimental plan based on a trim-offset approach is executed to minimize the thermal damage and to improve the surface fatigue strength, which is most desirable for a long operating life of the jet engine. An average cutting speed of ~1.5 mm/min is observed for rough-cut and ~5 mm/min for trim-cut operation. Six categories of wires are used to manufacture the turbine wheel slots without any wire breakage and gap-short issue. The fabricated profile slots have demonstrated an average roughness (Ra) of 0.65 μm, profile accuracy within ±5 μm, minimum hardness alteration (34.87 Hv), and negligible recast layer (<5 μm) using B-150 wire and fulfilled the essential requirements of the gas turbine industries. Compared to wire-electrochemical-machining (WECM), WEDM trim-offset approach is quite advantageous and should be beneficial for the researchers working in ‘Precision machining of aerospace materials’.     

冻结哈尔滨粉质粘土动三轴试验CT检测研究

基于对冻结哈尔滨粉质粘土动三轴试验前后试件CT检测结果，详细研究了冻土的强度、微观变形机制和结构损伤等变化特性及其与试验的负温和围压、土的含水量和容重、轴向荷载的振动频率和振动次数等主要影响因素之间的关系。     

哈尔滨市城市规划工作探索与实践

对哈尔滨“十五”期间的城市规划工作实践和成效进行了系统总结,并对“十一五”期间的城市规划工作进行了展望。     

哈尔滨工业大学早期建筑教育的实践教学

哈尔滨工业大学前身为中东铁路企业办学,早期建筑教育注重实践,属土木建筑领域的通才教育模式.文章对早期建筑教育创办背景、培养目标、教学内容、教学方法及专业师资构成等方面的"实践"权重做客观评介及深入思考.     

风电机组齿轮箱故障分类方法研究

风电机组齿轮箱的运行工况复杂多变,很难获取大量的所有已知故障的样本数据,为了能够实现在无已知样本数据条件下的故障分类,提出了一种基于ART2神经网络和C-均值聚类算法的风电机组齿轮箱故障分类方法。首先利用ART2无监督神经网络实现样本数据的初步分类,再利用C-均值聚类算法对分类结果进行修正,克服了由于原始神经网络算法存在"硬竞争"导致分类精度下降的问题。分析结果表明提出的方法具有更高的分类准确度,能够对健康和不同故障类型的风电机组齿轮箱进行准确分类识别。     

起动阶段涡轮导向叶片热应力及冷却作用研究

建立了涡轮导向叶片有限元分析模型,参照相关的试验数据和文献资料确定热边界条件,计算了发动机起动阶段涡轮导向叶片各瞬时的温度及热应力。分析所得高温、高应力区域与相似条件下某型发动机地面试车过程中出现裂纹的区域基本一致,验证了数值模拟过程的正确性。在此基础上,对比分析施加对流冷却与无冷却措施两种条件下的计算结果,发现对流冷却使叶片各点温度下降而应力升高,推断出温度与应力的变化趋势反向,因而在叶片冷却系统的设计中需要权衡温度与应力的关系。其结果与结论对叶片瞬态热应力计算和热疲劳分析有一定的借鉴意义。     

Gas-cooled reactor thermal hydraulic analyses with MELCOR

Pursuant to the Energy Policy Act of 2005, the High Temperature Gas-Cooled Reactor (HTGR) has been selected as the reference design for the Next Generation Nuclear Plant (NGNP). Stemming from a U.S. Nuclear Regulatory Commission (NRC) HTGR research initiative, a need was identified for validation of systems-level computer code modeling capabilities in anticipation of the eventual need to perform licensing analyses. Because the NRC has used MELCOR for light water reactors (LWR) in the past and because MELCOR was recently updated to include gas-cooled reactor (GCR) physics models, MELCOR is among the system codes of interest to the NRC. This paper describes MELCOR modeling of the General Atomics' Modular High Temperature Gas-Cooled Reactor (MHTGR). The MHGTR is a suitable design for demonstration of MELCOR GCR modeling competency for two reasons: 1) the MHTGR is a predecessor to the more advanced General Atomics’ Gas-Turbine Modular High Temperature Reactor (GTMHR), and 2) experimental data useful for benchmark calculations may soon become available. Using the most complete literature references available for the MHTGR design, researchers at Texas A&M University (TAMU) constructed a MELCOR input deck for the MHTGR to partially validate MELCOR GCR modeling capabilities. Normal and off-normal system operating conditions were modeled with appropriate boundary and initial conditions. MELCOR predictions of system response were obtained for steady-state, pressurized conduction cool-down (PCC), and depressurized conduction cool-down (DCC) scenarios. Code results were checked against nominal MHTGR design parameters, physical intuition, and anticipated GCR thermal hydraulic response. No inherent deficiencies in MELCOR modeling capability were observed, suggesting that the newly-implemented GCR models are adequate for systems-level analysis. If and when experimental benchmark data becomes available, further validation activities may proceed given the modeling efforts discussed herein.     

东北诸流域:哈尔滨城市空间营造

该文是个案研究系列之东北诸流域哈尔滨城市空间营造研究,对哈尔滨城市族群的更替叠累及城市空间营造进行了分析研究。     

Performance evaluation of a solarized gas turbine system integrated to a high temperature electrolyzer for hydrogen production

In this paper, the performance of a solar gas turbine (SGT) system integrated to a high temperature electrolyzer (HTE) to generate hybrid electrical power and hydrogen fuel is analyzed. The idea behind this design is to mitigate the losses in the electrical power transmission and use the enthalpy of exhaust gases released from the gas turbine (GT) to make steam for the HTE. In this context, a GT system is coupled with a solar tower including heliostat solar field and central receiver to generate electrical power. To make steam for the HTE, a flameless boiler is integrated to the SGT system applying the SGT extremely high temperature exhaust gases as the oxidizer. The results indicate that by increasing the solar receiver outlet temperature from 800 K to 1300 K, the solar share increases from 22.1% to 42.38% and the overall fuel consumption of the plant reduces from 7 kg/s to 2.7 kg/s. Furthermore, flameless mode is achievable in the boiler while the turbine inlet temperature (TIT) is maintained at the temperatures higher than 1314 K. Using constant amounts of the SGT electrical power, the HTE voltage decreases by enhancing the HTE steam temperature which result in the augmentation of the overall hydrogen production. To increase the HTE steam temperature from 950 K to 1350 K, the rate of fuel consumption in the flameless boiler increases from 0.1 m/s to 0.8 m/s; however, since the HTE hydrogen production increases from 4.24 mol/s to 16 mol/s it can be interpreted that the higher steam temperatures would be affordable. The presented hybrid system in this paper can be employed to perform more thermochemical analyses to achieve insightful understanding of the hybrid electrical power-hydrogen production systems.