基于变形补偿技术提高共轨高压泵泵油能力的试验研究

在有限元对共轨高压泵柱塞偶件径向变形进行仿真计算基础上,采用变形补偿技术设计出7种方案变形补偿柱塞偶件,在自制试验台上分别进行了密封性能试验、偶件变形测试及柱塞偶件载荷特性试验.试验结果表明,变形补偿是解决柱塞偶件超高压密封的有效途径;其中方案E偶件满足超高压下对密封性的要求,共轨压力为150 MPa时,高压泵容积效率可达88.21%.     

高比例二甲醚与柴油混合燃料对高压油泵柱塞偶件磨损的试验研究

二甲醚在传统柴油机应用存在着一个制约实用化的问题——二甲醚黏度极低导致柱塞偶件早期磨损及泄漏。把二甲醚与柴油按质量比7∶3混合(简称D70燃料),在高压油泵模拟试验台上对高压油泵柱塞偶件进行磨损测试试验,并与柴油的柱塞偶件磨损试验结果进行对比分析。结果表明,高比例二甲醚与柴油混合燃料相对于纯二甲醚可有效地改善高压油泵柱塞偶件早期磨损及泄漏。     

电控共轨高压油泵柱塞偶件设计及试验研究

对柱塞偶件在工作状态下的变形和泄漏进行了分析计算及试验研究。利用有限元分析技术,分别对几种柱塞偶件的设计方案进行了分析计算,着重解决了超高压工作条件下柱塞泵柱塞偶件,因其间隙大而产生的泄漏与间隙小所引发的卡滞之间的矛盾。试验结果表明,在保证良好润滑的条件下,设计的柱塞偶件在150MPa下的容积效率可达60％以上。     

关于喷油泵柱塞偶件配磨技术的研究与讨论(上)

从柱塞偶件配磨、表面粗糙度、相关性分析及零件质量控制的基本概念出发,对进口、国产配磨柱塞偶件圆柱工作表面粗糙度、质量检测指标相关性、柱塞偶件间隙与密封性能检测、耐久性磨损试验作对比分析,研究当前国内柱塞偶件配磨技术发展过程中在配磨零件锥度方向、关键部位质量控制方面存在和应该加以注意的问题,提出相关思路与解决方法。研究结果表明,从原理上讲,柱塞偶件配磨尽管是对柱塞偶件配合间隙控制最为理想的技术,由于国内、外喷油泵配磨柱塞偶件在表面粗糙度轮廓线形状、单件质量控制、锥度控制、间隙检测等方面存在较大的差距,完全实施柱塞偶件直接间隙控制取代密封性能检测的条件还不十分完善。研究同时还表明,配磨柱塞偶件在耐久性与磨损特性上相对传统研磨偶件具有明显的优势.     

关于喷油泵柱塞偶件配磨技术的研究与讨论(下)

从柱塞偶件配磨、表面粗糙度、相关性分析及零件质量控制的基本概念出发，对进口、国产配磨柱塞偶件圆柱工作表面粗糙度、质量检测指标相关性、柱塞偶件间隙与密封性能检测、耐久性磨损试验作对比分析，研究当前国内柱塞偶件配磨技术发展过程中在配磨零件锥度方向、关键部位质量控制方面存在和应该加以注意的问题，提出相关思路与解决方法。研究结果表明，从原理上讲，柱塞偶件配磨尽管是对柱塞偶件配合间隙控制最为理想的技术，由于国内、外喷油泵配磨柱塞偶件在表面粗糙度轮廓线形状、单件质量控制、锥度控制、间隙检测等方面存在较大的差距，完全实施柱塞偶件直接间隙控制取代密封性能检测的条件还不十分完善。研究同时还表明，配磨柱塞偶件在耐久性与磨损特性上相对传统研磨偶件具有明显的优势。     

桩塞偶件磨损性能实验研究与机理分析

通过对柱塞偶件1000小时跑合试验径部密封秒数下降实验数据的对比分析,探讨了在实际工作条件下影响柱塞偶件磨损的主要原因。分析了柱塞偶件磨损过程中存在的主要磨损形式,并在这一基础上提出相应的改进措施。     

喷油泵顶隙式柱塞偶件性能试验研究

对喷油泵顶隙式柱塞偶件、非顶隙式柱塞偶件以及等压出油阀、阻尼阀做交叉试验,通过喷油泵泵端压力、嘴端压 力、喷油速率、喷油始点、单喷射油量的检测分析,研究当前直列高喷射压力条件下,顶隙式柱塞偶件的喷油提前特性及 其对喷油泵综合性能的影响。研究结果表明,在喷油泵工作转速与循环油量范围内,顶隙式柱塞偶件较普通型柱塞偶件 而言,有1．8°的喷油提前功能,泵端压力、嘴端压力、喷油速率性能基本一致。除此以外,顶隙式柱塞偶件还可以降低喷 油泵中、低速油量,从而可以调整供油速度特性。     

采用配磨工艺柱塞偶件的试验研究

本文简要阐明了柱塞偶件配磨的工作原理、径部间隙的选择原则和采用配磨工艺柱塞偶件所做的质量摸底、装泵试验及可靠性冷跑试验。     

采用配磨工艺柱塞偶件的试验研究

本文简要阐明了柱塞偶件配磨的工作原理、径部间隙的选择原则和采用配磨工艺柱塞偶件所做的质量摸底、装泵试验及可靠性冷跑试验.     

Ⅰ号泵柱塞偶件的防漏结构设计

本文介绍防漏原理在Ⅰ号泵柱塞偶件防漏结构设计中的应用。经750小时冷拖试验及用户批量使用证实,采用防漏柱塞偶件是减少Ⅰ号系列泵内漏故障的有效措施。     

New capability of graphene as hydrogen storage by Si and/or Ge doping: Density functional theory

We studied the adsorption of water molecules via the density functional theory on the pure and silicon and/or germanium doped graphene. We investigated the electrostatic surface potential of the structures to predict the possible interactions. Also, we examined the interaction between every possible side of the water molecule and possible sites of the pure and doped graphene. There was no interaction between the water molecule and the graphene. The only interaction was between the oxygen atom of the water molecule and the doped atoms. We also studied the decomposition of the water molecule on these doped graphene sheets and the possible intermediates and transition states and reaction pathway for the decomposition process. We calculated the interaction energies for the adsorption steps and the thermodynamic parameters for all steps of reaction pathway. The results showed that the adsorption of the water molecule on silicon and/or germanium doped graphene. Also, the decomposition of one of the hydrogen atoms of water molecule was thermodynamically favored at room temperature.     

Research progress on hydrate plugging in multiphase mixed rich-liquid transportation pipelines

The plugging mechanism of multiphase mixed rich-liquid transportation in submarine pipeline is a prerequisite for maintaining the fluid flow in the pipeline and ensuring safe fluid flow. This paper introduced the common experimental devices used to study multiphase flow, and summarized the plugging progress and mechanism in the liquid-rich system. Besides, it divided the rich-liquid phase system into an oil-based system, a partially dispersed system, and a water-based system according to the different water cuts, and discussed the mechanism of hydrate plugging. Moreover, it summarized the mechanism and the use of anti-agglomerates in different systems. Furthermore, it proposed some suggestions for future research on hydrate plugging. First, in the oil-based system, the effect factors of hydrates are combined with the mechanical properties of hydrate deposit layer, and the hydrate plugging mechanism models at inclined and elbow pipes should be established. Second, the mechanism of oil-water emulsion breaking in partially dispersed system and the reason for the migration of the oil-water interface should be analyzed, and the property of the free water layer on the hydrate plugging process should be quantified. Third, a complete model of the effect of the synergy of liquid bridge force and van der Waals force in the water-based system on the hydrate particle coalescence frequency model is needed, and the coalescence frequency model should be summarized. Next, the dynamic analysis of a multiphase mixed rich-liquid transportation pipeline should be coupled with the process of hydrate coalescence, deposition, and blockage decomposition. Finally, the effects of anti-agglomerates on the morphological evolution of hydrate under different systems and pipeline plugging conditions in different media should be further explored.     

烘焙对生物质热化学转化特性影响的研究进展

生物质是可再生能源的重要组成部分,储量巨大,但其含水量高、能量密度和热值低等缺点致使其研磨难度大、存储运输不便,难以资源化利用。本文对烘焙预处理技术的过程及特点、能耗分析和较为理想的烘焙标准进行了简述;并重点阐述了烘焙对生物质燃烧、热解和气化特性影响的研究进展。经烘焙处理后的生物质在炉膛内可快速、稳定燃烧,炉内温度迅速升高,产生的烟气量减少;热解产生的生物质焦油中水和乙酸含量明显减少,苯酚含量增加,热值总体升高;气化合成气品质明显提升,能量密度增大,总气化效率显著提高。此外,对烘焙预处理技术在城市固体废弃物处理的应用进行了简要的概述,并对其在生物质和城市固体废弃物研究方向上进行了展望。     

Semi-analytical method for heat and moisture transfer in packed bed of silica gel

A semi-analytical model for the heat and mass transfer of adsorption and desorption processes of the vertical solid desiccant packed bed dehumidifier is presented on the basis of quasi-steady state assumption, and is solved using close form integration with the limits equivalent to bed and time increments, and numerically by Runge-Kutta Fehlberg and forward scheme finite difference techniques. The most important parameters during the dehumidifier operation, namely, (i) exit air temperature and humidity, (ii) axial temperature distribution in the bed and (iii) water content are evaluated. Stability of the semi-analytical method is investigated and found that the main parameters affecting the model stability are the bed and time increments size. A dimensionless parameter combining time and bed increments size and air velocity named velocity ratio is defined and investigated. It is found that when the velocity ratio equals the ratio of particle diameter to bed length, the method is stable, and as the velocity ratio is made smaller beyond the stable velocity ratio, the results remain unchanged. The results of semi-analytical and numerical models agree well with the experimental results for both desorption and adsorption processes. Using the proposed semi-analytical model, the minimum and maximum relative errors for exit air temperature are 2.24% and 11.78%, respectively and for exit air humidity the minimum and maximum errors are 3.79% and 27.17% respectively.     

Energy use in Indian household sector – An actor-oriented approach

Over the years, significant changes have taken place with regard to the type as well the quantity of energy used in Indian households. Many factors have contributed in bringing these changes. These include availability of energy, security of supplies, efficiency of use, cost of device, price of energy carriers, ease of use, and external factors like technological development, introduction of subsidies, and environmental considerations. The present paper presents the pattern of energy consumption in the household sector and analyses the causalities underlying the present usage patterns. It identifies specific (groups of) actors, study their specific situations, analyse the constraints and discusses opportunities for improvement. This can be referred to “actor-oriented” analysis in which we understand how various actors of the energy system are making the system work, and what incentives and constraints each of these actors is experiencing. It analyses actor linkages and their impact on the fuel choice mechanism. The study shows that the role of actors in household fuel choice is significant and depends on the level of factors – micro, meso and macro. It is recommended that the development interventions should include actor-oriented tools in energy planning, implementation, monitoring and evaluation. The analysis is based on the data from the national sample survey (NSS), India. This approach provides a spatial viewpoint which permits a clear assessment of the energy carrier choice by the households and the influence of various actors. The scope of the paper is motivated and limited by suggesting and formulating a powerful analytical technique to analyse the problem involving the role of actors in the Indian household sector.     

考虑黏性效应的半潜浮式风力机动力特性研究

对半潜浮式风力机动力特性进行研究，推导考虑黏性阻尼的动力学方程及传递函数。对黏性效应的影响及其计算方法进行探讨，对比附加阻尼矩阵法、Morison单元法的优缺点，并提出考虑黏性阻尼效应水动力计算的混合法，在此基础上对半潜浮式风力机气动-水动-锚泊全耦合动力响应进行分析。结果表明：黏性效应主要影响共振周期附近的响应值，在数值分析时不可忽略；附加阻尼矩阵法在考虑水平面内运动黏性阻尼时有所不足，且无法考虑黏性效应对共振周期的影响，Morison单元法在考虑垂荡、转动黏性阻尼时有所不足，混合法是考虑黏性阻尼水动力计算的更有效方法；该半潜浮式风力机垂荡和纵摇响应主要受波浪控制，而水平面内运动受风、浪、流联合作用的影响；浮式风力机运动和加速度的最危险工况可发生在发电工况时，最大锚链张力发生在极端环境条件时。     

Theoretical and experimental investigations of a liquid desiccant filmed cellulose fibre heat and mass exchanger

This paper presented theoretical and experimental investigations of a liquid desiccant filmed cellulose fibre heat and mass exchanger, a new type of exchanger with the potential to be an alternative to a conventional exchanger. Owing to the complexity of the desiccant assisted heat and mass transfer and difficulty in determining its associated parameters, work started from the simulation of a clear fibre exchanger by developing a dedicated numerical model, and its validation by using the data from the manufacturer of the exchanger. Further to this, laboratory testing was carried out with the same exchanger, but filmed with a liquid desiccant fluid, i.e. LiCl. Comparison between the data of the clear and desiccant filmed exchangers suggested the use of correction factors for heat and mass transfer resistances with desiccant operation. A revised model for the desiccant filmed exchanger was then established taking into account the correction factors. By using the updated model, influence of geometrical sizes and operating conditions of the liquid desiccant filmed exchanger on the exchanger efficiency were studied and the optimal values of these were obtained. The results indicated that the exchanger efficiencies (heat, mass and enthalpy) are largely dependent upon the exchanger channel length, air flow rate and less related to the exchanger channel height, intake air temperature and intake‐to‐outgoing air moisture content difference. It was also suggested that the air speed across the channels should be in the range 0.5–1.5 m s^?1. The height of air channel (passage) should be set at 6.5 mm or below and its length should be 1.0 m or more. A simulation was carried out under UK typical summer operation conditions, i.e. the intake air streams at 30°C db and 70% rh and outgoing air streams at 24°C db and 50% rh, and the results indicated that the exchanger with the above recommended geometrical sizes can achieve an energy efficiency of 87%, which is 30% higher than for non‐desiccant filmed operation. Copyright © 2009 John Wiley & Sons, Ltd.     

A critical review of ash slagging mechanisms and viscosity measurement for low-rank coal and bio-slags

Gasification or combustion of coal and biomass is the most important form of power generation today. However, the use of coal/biomass at high temperatures has an inherent problem related to the ash generated. The formation of ash leads to a problematic phenomenon called slagging. Slagging is the accumulation of molten ash on the walls of the furnace, gasifier, or boiler and is detrimental as it reduces the heat transfer rate, and the combustion/gasification rate of unburnt carbon, causes mechanical failure, high-temperature corrosion and on occasions, superheater explosions. To improve the gasifier/combustor facility, it is very important to understand the key ash properties, slag characteristics, viscosity and critical viscosity temperature. This paper reviews the content, compositions, and melting characteristics of ashes in differently ranked coal and biomass, and discusses the formation mechanism, characteristics, and structure of slag. In particular, this paper focuses on low-rank coal and biomass that have been receiving increased attention recently. Besides, it reviews the available methodologies and formulae for slag viscosity measurement/prediction and summarizes the current limitations and potential applications. Moreover, it discusses the slagging behavior of different ranks of coal and biomass by examining the applicability of the current viscosity measurement methods to these fuels, and the viscosity prediction models and factors that affect the slag viscosity. This review shows that the existing viscosity models and slagging indices can only satisfactorily predict the viscosity and slagging propensity of high-rank coals but cannot predict the slagging propensity and slag viscosity of low-rank coal, and especially biomass ashes, even if they are limited to a particular composition only. Thus, there is a critical need for the development of an index, or a model or even a measurement method, which can predict/measure the slagging propensity and slag viscosity correctly for all low-rank coal and biomass ashes.     

Exergoeconomic analysis and optimization of basic,dual-pressure and dual-fluid ORCs and Kalina geothermal power plants: A comparative study

In present work, the basic, dual-pressure and dual-fluid ORCs and Kalina cycle for power generation from the geothermal fluid reservoir are compared from energy, exergy and exergoeconomic viewpoints. To do so, first thermodynamic models are applied to the considered cycles; then by developing cost flow rate balance and auxiliary equations using SPECO method for all components, the cost flow rate and unit cost of exergy for each stream are calculated. The results show that the turbine in basic and Kalina cycles and low pressure turbine in dual-pressure and dual-fluid ORCs have the maximum value of sum of total cost rate associated with exergy destruction and total capital investment cost rate. Thus, more attention should be paid for these components from the exergoeconomic viewpoint. The cycles are optimized to obtain maximum produced electrical power in the cycles as well as minimum unit cost of produced power. The optimization results show that among the considered cycles, dual-pressure ORC has the maximum value of produced electrical power. This is 15.22%, 35.09% and 43.48% more than the corresponding values for the basic ORC, dual-fluid ORC and Kalina cycle, respectively in optimal condition. Also Kalina cycle has the minimum value of unit cost of power produced and its value in optimum state is 26.23%%, 52.09% and 66.74% less than the corresponding values for the basic ORC, dual-pressure ORC and dual-fluid ORC, respectively in optimal condition. Finally a parametric study is carried out to assess the effects on thermodynamic and exergoeconomic parameters of the considered cycles of operating pressures and ammonia mass concentration.