解决过压吸收片负影响的一种电路改进建议

1　前言DF4B型机车控制电路中相关电磁接触器线圈和继电器线圈上并联有过电压吸收片,目的是减少和消除线圈失电时释放的过电压对机车运行记录监控器等装置的干扰。但过电压吸收片的接入却往往引起电路故障的发生。2　故障现象和原因分析我段DF4B型3651号机车和0627号机车在     

DF4D型机车电路接地故障的解决措施

1问题的提出 DF4D型机车与DF10D型机车相比,电气故障率明显下降,牵引性能却大大提高。然而,随着机车运行速度的不断提高,机车振动加剧,对预防、根治机车电气线路接地的故障也提出了新的要求。虽然一点接地不会造成机车的重大破损,但机车主电路、励磁电路、控制电路或照明电路中一旦发生正负同时接地,后果往往比较严重。因此,预防、根治DF4D型机车电气线路接地仍是机车检修过程中的一个不可掉以轻心的工作。     

DF4B型机车接触器加装过压吸收片产生的不正常现象原因分析及建议

1 问题的提出 随着对机车监控要求的提高，铁道部对所有DF4B型机车要求改装LKJ-93型监控装置，在改装时明确要求：在机车控制电路中相关电磁接触器线圈和继电器线圈上并联过电压吸收片，以减少线圈失电时释放的过压干扰监控装置正常工作。     

DF型机车加装主电路接触器第二电源的改造措施

1问题的提出沈阳机务段配属DF4D型机车68台,DF11型机车48台,DF11G型机车20台,2007年以来,平均每年发生机车主电路接触器LLC（励磁机励磁接触器）、LC（主发电机励磁接触器）、1—6C不吸合故障48件,造成机破事故26件,占全年机破总数的30％,严重影响机车质量和铁路运输秩序。     

C4型联合调节器负载游车的原因分析

1问题的提出 DF5型机车有两种励磁控制方式:一种是电子恒功励磁,靠微机来控制励磁电流的大小;另一种是靠联合调节器的功调电阻来控制励磁电流的大小.机车正常情况下使用电子恒功励磁,在电子恒功励磁出现故障的时候人工转换成联合调节器励磁.大连机务段配属的32台DF5型机车,全部使用C4型联合调节器,机车经过中修后使用一个阶段,联合调节器就开始出现原励磁负载状态下游车的故障,有的调节器还反复出现.由于DF5型机车没有自负载装置,因此每次出现这种故障都必须进行水阻试验,不仅耗费很多人力和物力,还给机务段的生产带来影响.     

消除内燃机车主电路接地保护"盲区"的措施

以DF11型机车为例,分析了内燃机车接地保护电路的工作原理及存在的“盲区”,提出了消除主电路接地保护“盲区”的措施。     

DF5型机车前后头灯照明电路的改进

1问题的提出DF5型机车是杭州机务段金华折返段配属的调车机车,3年来该段已陆续配属了7台DF5型新机车,担当着金西、金东、义乌、衢州、江山、千岛湖等站场的调车任务。机车头灯照明电路中的2个HKF触头惯性烧损问题比较突出。经初步统计,每台机车在一个定修期(3个月)内需要更换HK     

DF4DD 型机车 DLC 控制器副板烧损原因分析及解决措施

分析了 DF4DD 型机车 DLC 控制器副板烧损故障的主要原因,并通过技术改进措施,进一步提高了电路的可靠性。     

DF4B型机车的起动电路分析及改进建议

通过对DF4B型机车起动电路原理结构的分析 ,找到了机车主接触器主触头烧损的原因 ,指出该电路存在的缺陷 ,并提出改进建议。     

机车励磁整流柜二极管击穿的应急处理方法

1问题的提出乌鲁木齐机务段配属担当干线货运的DF8B型机车214台、DF4B型机车190台、DF4C型机车20台,担当客运的DF11、DF4DK型和DF4DK准高速型机车共68台,每年均发生6～8起励磁整流柜二极管元件击穿故障。因乘务员在途中无法处理,造成机破,扰乱了     

对DF5型机车轴重调整过程的分析及新设想

通过对DF5型机车轴重调整过程的分析,提出了该型机车的轴重调整方法,该方法一直指导着DF5型机车的轴重调整,保证了在铁路线上运营的近1200台机车的轴重均匀。     

Characterisation and effect of using waste plastic oil and diesel fuel blends in compression ignition engine

Plastics have now become indispensable materials in the modern world and application in the industrial field is continually increasing. The properties of the oil derived from waste plastics were analyzed and found that it has properties similar to that of diesel. Waste plastic oil (WPO) was tested as a fuel in a D.I. diesel engine and its performance characteristics were analysed and compared with diesel fuel (DF) operation. It is observed that the engine could operate with 100% waste plastic oil and can be used as fuel in diesel engines. Oxides of nitrogen (NO_x) was higher by about 25% and carbon monoxide (CO) increased by 5% for waste plastic oil operation compared to diesel fuel (DF) operation. Hydrocarbon was higher by about 15%. Smoke increased by 40% at full load with waste plastic oil compared to DF. Engine fueled with waste plastic oil exhibits higher thermal efficiency upto 80% of the full load and the exhaust gas temperature was higher at all loads compared to DF operation.     

基于面向对象技术的内燃机车水阻试验系统程序设计

介绍了基于面向对象技术的东风系列机车水阻试验系统软件设计以及软件设计中的若干技术问题。     

Performance and emission characteristics of a turpentine–diesel dual fuel engine

This paper describes an experimental study concerning the feasibility of using bio-oil namely turpentine obtained from the resin of pine tree. The emission and performance characteristics of a D.I. diesel engine were studied through dual fuel (DF) mode. Turpentine was inducted as a primary fuel through induction manifold and diesel was admitted into the engine through conventional fueling device as an igniter. The result showed that except volumetric efficiency, all other performance and emission parameters are better than those of diesel fuel with in 75% load. The toxic gases like CO, UBHC are slightly higher than that of the diesel baseline (DBL). Around 40–45% smoke reduction is obtained with DF mode. The pollutant No_x is found to be equal to that of DBL except at full load. This study has proved that approximately 75% diesel replacement with turpentine is possible by DF mode with little engine modification.     

A numerical study on the effects of constant volume combustion phase on performance and emissions characteristics of a diesel-hydrogen dual-fuel engine

A detailed numerical study is carried out to investigate the performance of a diesel-hydrogen dual fuel (DF) compression ignition engine operating under a novel combustion strategy in which diesel injection and most of the combustion occur at a constant volume. A detailed validation of the numerical model for diesel-hydrogen DF engine operation has been carried out. Then a parametric study has been performed to investigate the effects of the constant volume combustion phase (CVCP) at up to 90% hydrogen energy share (HES) on engine performance and emissions at low and high load with comparisons to the conventional engine. The results demonstrate that the CVCP strategy can improve thermal efficiency at all HESs and load conditions with far lower carbon-based emissions. Conventional DF engines struggle at low load high HESs due to the reduced diesel injection failing to ignite the leaner premixed charge. Through use of a CVCP thermal efficiency at low load 90% HES increased from 11% to 38% with considerably reduced hydrogen emission due to the increased temperatures and pressures allowing for the wholesale ignition of the hydrogen-air mix. It was also found that increasing the time allowed for combustion within the CVCP, by advancing the diesel injection, can lead to even further thermal efficiency gains while not negatively impacting emissions.     

Performance and emission characteristics of turpentine–diesel dual fuel engine and knock suppression using water diluents

In the present work, a normal diesel engine was modified to work in a dual fuel (DF) mode with turpentine and diesel as primary and pilot fuels, respectively. The resulting homogeneous mixture was compressed to a temperature below the self‐ignition point. The pilot fuel was injected through the standard injection system and initiated the combustion in the primary‐fuel air mixture. The primary fuel (turpentine) has supplied most of the heat energy. Usually, in all DF engines, low‐cetane fuels are preferred as a primary fuel. Therefore, at higher loads these fuels start knocking and deteriorating in performances. Usually, DF operators suppress the knock by adding more pilot‐fuel quantity. But in the present work, a minimum pilot‐fuel quantity was maintained constant throughout the test and a required quantity of diluent (water) was added into the combustion at the time of knocking. The advantages of this method of knock suppression are restoration of performance at full load, maintenance of the same pilot quantity through the load range and reduction in the fuel consumption at full load. From the results, it was found that all performance and emission parameters of turpentine, except volumetric efficiency, are better than those of diesel fuel. The emissions like CO, UBHC are higher than those of the diesel baseline (DBL) and around 40–45% reduction of smoke was observed at 100% of full load. The major pollutant of diesel engine, NO_x, was found to be equal to that of DBL. From the above experiment, it was proved that approximately 80% replacement of diesel with turpentine is quite possible. Copyright © 2006 John Wiley & Sons, Ltd.     

Theoretical and experimental investigation of total equivalent temperature difference (TETD) values for building walls and flat roofs in Turkey

The aim of this study is to find time lag (TL), decrement factor (DF) and total equivalent temperature difference (TETD) values for multilayer walls and flat roofs of buildings using experimental and theoretical methods, and to compare the experimental results with theoretical ones. The TETD is a method for calculating cooling load due to heat gain from the walls or flat roofs, and it can be obtained using values of inside and outside air temperatures, solar radiation, TL and DF. The TL and DF depend on the highest and the lowest temperatures at the inner and outer surfaces of the walls or flat roofs, and the time periods involved in reaching these temperatures. Hence, two testing rooms each consisting of four multilayered walls and a flat roof, air conditioner, measuring elements are built to measure all required temperatures. The required temperatures, which are hourly inside and outside air temperatures, and surface temperatures of each structure layer, are measured in every minute during testing periods of the 2007 summer season of Gaziantep, Turkey. Hourly solar radiation values on the walls are computed using hourly measured solar radiation on a horizontal surface. The TL, DF and TETD values of eight different walls and two different flat roofs commonly used in Turkey are computed utilizing the measured temperature and solar radiation values. The computed values for the TL, DF and TETD are compared with theoretical results obtained numerically using periodic solution of one dimensional transient heat transfer problem for the same structures.     

Experimental investigation on a DI dual fuel engine with hydrogen injection

Over the past two decades considerable efforts have been undertaken to develop and introduce new alternative fuels for the conventional gasoline and diesel. Many alternative fuels, both liquid and gaseous, have been experimented and some have even been commercialized such as ethanol, natural gas, etc. Hydrogen has been considered as an excellent fuel to replace the petroleum‐based fuels due to its clean burning characteristics. In the present experimental investigation, hydrogen was injected in the intake manifold and diesel fuel was injected inside the engine cylinder in the conventional manner. Hydrogen injection parameters such as injection timing, injection duration and quantity of hydrogen injected were optimized based on the performance and emission characteristics. Exhaust gas recirculation (EGR) technique was adopted to reduce the oxides of nitrogen emission. From the results it was observed that for hydrogen diesel dual fuel (DF) engine, the optimal operating parameters for hydrogen injection were start of injection at gas exchange top dead centre with injection duration of 30° crank angle with the hydrogen flow rate of 7.5 litres per minute (lpm). With EGR the optimized condition was found to be 20% for the entire load. The brake thermal efficiency with 20% EGR increases by 16% at 75% load as compared with diesel, while at full load it reduces by 8% due to the recirculation of exhaust gases that results in a reduction of intake oxygen concentration compared with part load. NO_X emission decreases by five and half times, while other emissions increase by 1.4 times as compared with DF engine. Copyright © 2008 John Wiley & Sons, Ltd.     

大功率机车柴油机燃油喷射系统改进

针对东风8B型大功率机车柴油机燃油喷射系统故障率明显上升的问题,采用短针阀喷油器、新型柱塞偶件、等压出油阀对其进行了比较全面的改进研究.改进系统在机车上的实际运行情况表明:改进系统提高了其零部件工作可靠性,延长了使用寿命,同时也改善了部分负荷工况下的燃油经济性.     

Promoting dark fermentation for biohydrogen production: Potential roles of iron-based additives

Dark fermentation (DF) is a promising technology for biohydrogen production. Low efficiency of biohydrogen production is a bottleneck of the scale-up prospects for DF. Additives have been extensively studied to improve the biohydrogen production efficiency. Among of them, iron-based additives present a promising application potential due to their demonstrated significant enhancement of DF efficiency and among the low-cost bioactive agents. However, current reviews mainly examined the effects of nano-materials on DF and an in-depth analysis of enhancing mechanisms with addition of iron-based additives in DF is still lacking. To this end, this article comprehensively reviewed and evaluated the effects of iron-based additives on DF. Further, the potential mechanisms, including altering metabolic pathways, improving activities of microbes and enzymes, promoting electron delivery, and enriching hydrogen-producing bacteria, were discussed. Lastly, prospects and challenges of iron-based additives for subsequent research and large-scale application for DF were summarized.