通用小型汽油机油气混合的两相流动与排放研究

化油器是通用小型汽油机中最重要的装置,其作用是控制汽油机各工况油气混合浓度和燃油雾化混合质量.本文以168F汽油机化油器为例,应用两相流理论通过实验对油气混合过程进行分析,通过改变化油器各量孔和泡沫管参数匹配,控制混合气的浓度变化,从而有效改善通用小型汽油机的燃料经济性和排放,优化汽油机综合性能.     

不同尺寸主供油量孔对CQ188F汽油机排放性能的影响分析

过量空气系数对通用小型汽油机排放性能影响最大,以CQ188F汽油机为例,通过改变化油器主供油量孔尺寸来改变过量空气系数,进行整机性能和排放性能试验,对比在不同主供油量孔尺寸下整机排放值和燃油消耗率数值,选取能够有效改善汽油机经济性和排放优化的方案,依据汽油机在不同使用国对性能和排放要求确定匹配方案,优化CQ188F汽油机综合性能,达到节能减排的目的。     

过量空气系数对四冲程小型通用汽油机排放的影响

本文介绍了国内小型通用汽油机的发展概况和特点，针对美国和欧洲有关小型通用汽油机的排放限值要求，对188F小型通用汽油机进行台架试验研究，得出了目前国内影响通用汽油机排放的主要因素是各种工况下的油气混合比例，给出了过量空气系数与小型通用汽油机的CO、HC和NOx排放之间的变化规律，提出了兼顾汽油机动力性、经济性、工作稳定性和低的排放性能来优化化油器过量空气系数特性的有效措施。     

“机械工业部小型汽油机化油器行业第二次大会”胜利召开

机械工业部小型汽油机化油器行业第二次大会于1984年9月2日至10日在青岛市召开。会议由青岛市化油器厂主持,参加会议的有机械工业部农机配件公司、行业组全体成员、部分行业组外小化油器生产厂及主机厂等21个单位共43名代表。会议总结了第一届行业组的工作,改选第二届行业组领导机构,制订了今后两年行业活动计划、听取了赴美赴日考察报告、进行了学术交流,审议了通用小型汽油机化油器试验方法及“通用小型汽油机化油器产     

实现小型二冲程汽油机分层扫气的膜片式喷射化油器

发明并研究了一种结构简单的膜片式喷射化油器（ＤＩＣ）,其工作原理是利用曲轴箱峰值压力给燃油加压,由一组膜片机构将进气喉口处的压差转换到燃油主量孔两侧,使供油量与进气量成正比,从而实现燃油的计量和喷射。本系统和适当的扫气系统结合起来,可实现小型二冲程汽油机的分层扫气,减少燃油的短路损失,大幅度降低油耗和未燃碳氢排放。本文还提出了保留常规化油器的低负荷供油系统,用来解决一般简单喷射系统低负荷性能恶化的问题,又使燃油系统结构大为简化。本文描述了ＤＩＣ的基本概念和工作原理,并在３０ｃｍ３试验专用汽油机上进行了膜片式喷射化油器供油特性和发动机性能的对比试验。     

小型汽油机化油器行业组成立会议在涪陵召开

为了不断地提高小型汽油机化油器的产品质量,广泛地进行技术情报交流,开展企业间的评比活动,不断提高企业管理水平,在机械工业部农机工业局领导下,在四川省涪陵地区农机局、涪陵化油器厂积极支持下,“机械工业部小型汽油机化油器行业组成立会议”于1982年12月10至15日在四川涪陵召开。出席会议的有23个单化,43名代表。会议学习了“农机行业组工作条例(试行)”,听取了天津内燃机研究所化油器组关于小型汽油机化油器行业组筹备工作的汇报,推选了行业组的正副组长,讨论、研究了行业组1983至1984两年的活动计划。会议认真讨论并通过了天津内燃机研究所提出的报部审批标准《小型汽油机化油器技术条件(讨论稿)”和“机械工业部小型汽油机化油器创部优质产品质量检测暂行办法(修改稿)”,待进一步复核后按规定程序上报审批。研究制定了“小型汽油机化油器清洁度测定     

日本通用小型四冲程汽油机主要零件尺寸分析

1.前言日本通用小型汽油机的产量,1986年已达497万台、1899万马力,仅次干美国。本文拟对其四冲程汽油机的主要零件结构尺寸进行统计、分析,以供从事这类汽油机研究、设计的工作者参考。分析数据来源于日本1986年的资料,共13个厂家、158种机型。此外,日本有3个厂家生产通用小型四冲程煤油机,共10种机型,都是四冲程汽油机的变型产品,其尺寸与同类型的汽油机相同,文中未作统计。     

通用小型汽油机工况法燃油消耗率测试方法解析

GB/T 37692-2019《非道路移动机械用小型点燃式发动机工况法燃油消耗率限值与测量方法》标准于2019年6月4日发布,将于2020年1月1日正式实施。本文根据标准内容,从试验条件、仪器设备、试验工况的选择、试验流程和数据计算等要点,对通用小型汽油机工况法燃油消耗率测试方法要求进行了解读,为检测机构和企业进行通用小型汽油机油耗测试提供参考。     

电控化油器的开发研究

现代电子技术的发展，为汽油机供油系统燃油精确供给，提供了有力的保证。本文将以CG125摩托车为例，阐述电子控制技术在汽油机供油系统上的应用，即电控化油器系统。     

重庆通用小型汽油机的现状及前景

由于通用小型汽油机具有体积小、重量轻、价格低廉、使用方便等显著特点，因而在我国具有广阔的发展前景。重庆直辖之后，特别是民营企业重庆北碚腾龙机械厂于1999年率先开发生产通用小型汽油机以来，在不到5年的时间里，重庆通用小型汽油机获得了长足的发展。目前不仅在重庆掀起了一股“通用小型汽     

提高12V20/27柴油机功率的研究

分析了提高12V20/27柴油机功率的可行性,并在此基础上指出:在原柴油机结构尺寸不做大的变动的前提下,采取调整压缩比、加大空冷器冷却面积、加大供油量和调整增压器元件等四项措施可达到功率提高的目的。     

泡沫陶瓷中燃油喷雾液滴蒸发混合的数值研究

将孔隙率0．85的泡沫陶瓷简化为由128个正方形格栅等间距排列构成的区域,在二维计算区域中,用反弹模型模拟液滴与泡沫陶瓷及边界壁面碰撞后液滴运动轨迹的变化．在不同的栅格壁面温度、喷雾锥角及燃料喷雾速度时,在常压及层流状态下,研究喷雾液滴在泡沫陶瓷中的蒸发特性．计算结果表明,泡沫陶瓷温度是决定燃油蒸发速率的关键因素;大喷雾锥角时,燃油蒸气分布较均匀;减小喷雾速度会使燃油蒸气分布不均匀．     

双燃料发动机油气双闭环控制策略应用研究

根据改装的双燃料发动机特点设计了基于当量燃料的油气控制策略,该控制策略通过柴油天然气双闭环实现两种燃料的合理控制,并在改装成双燃料发动机的潍柴X6170上进行试验。试验表明,在不改变原柴油机主要结构下,改装双燃料发动机能够替代原柴油机作为船舶动力,燃油消耗降低且排放相应减少,能够平稳进行油气切换,替代率过大时对HC排放及排气温度影响较大。     

Development of porous carbon foam polymer electrolyte membrane fuel cell

In order to prove the feasibility of using porous carbon foam material in a polymer electrolyte membrane fuel cell (PEMFC), a single PEMFC is constructed with a piece of 80PPI (pores per linear inch) Reticulated Vitreous Carbon (RVC) foam at a thickness of 3.5 mm employed in the cathode flow-field. The cell performance of such design is compared with that of a conventional fuel cell with serpentine channel design in the cathode and anode flow-fields. Experimental results show that the RVC foam fuel cell not only produces comparative power density to, but also offers interesting benefits over the conventional fuel cell. A 250 h long term test conducted on a RVC foam fuel cell shows that the durability and performance stability of the material is deemed to be acceptable. Furthermore, a parametric study is conducted on single RVC foam fuel cells. Effect of geometrical and material parameters of the RVC foam such as PPI and thickness and operating conditions such as pressure, temperature, and stoichiometric ratio of the reactant gases on the cell performance is experimentally investigated in detail. The single cell with the 80PPI RVC foam exhibits the best performance, especially if the thinnest foam (3.5 mm) is used. The cell performance improves with increasing the operating gauge pressure from 0 kPa to 80 kPa and the operating temperature from 40 °C to 60 °C, but deteriorates as it further increases to 80 °C. The cell performance improves as the stoichiometric ratio of air increases from 1.5 to 4.5; however, the improvement becomes marginal when it is raised above 3.0. On the other hand, changing the stoichiometric ratio of hydrogen does not have a significant impact on the cell performance.     

Performance study of a solid oxide fuel cell and gas turbine hybrid system designed for methane operating with non-designed fuels

This paper presents an analysis of the fuel flexibility of a methane-based solid oxide fuel cell-gas turbine (SOFC-GT) hybrid system. The simulation models of the system are mathematically defined. Special attention is paid to the development of an SOFC thermodynamic model that allows for the calculation of radial temperature gradients. Based on the simulation model, the new design point of system for new fuels is defined first; the steady-state performance of the system fed by different fuels is then discussed. When the hybrid system operates with hydrogen, the net power output at the new design point will decrease to 70% of the methane, while the design net efficiency will decrease to 55%. Similar to hydrogen, the net output power of the ethanol-fueled system will decrease to 88% of the methane value due to the lower cooling effect of steam reforming. However, the net efficiency can remain at 61% at high level due to increased heat recuperation from exhaust gas. To increase the power output of the hybrid system operating with non-design fuels without changing the system configuration, three different measures are introduced and investigated in this paper. The introduced measures can increase the system net power output operating with hydrogen to 94% of the original value at the cost of a lower efficiency of 45%.     

Catalytic combustion of hydrogen—II. An experimental investigation of fundamental conditions for burner design

The performance of catalysts in different forms was investigated for the design of a catalytic combustor with hydrogen fuel. The catalysts tested had dimensions of 150 × 150 mm, and consisted of a ceramic honeycomb impregnated with Pt, two Ni metal foams coated with Pd powder which differed from each other in pore size, and a ceramic foam coated with Co-Mn-Ag oxide powder. In the diffusive mode of operation, the Pd-coated Ni foam with larger pores exhibited the highest combustion efficiency. The ceramic foam with the oxide coating also provided smooth hydrogen combustion in the range 0.2–1.0 kcal cm^?2 h^?1. Combustion efficiency was improved by increasing the amount of premixed air and totally supplied air. Spot measurements of surface temperature and gas composition were carried out over the catalyst surface and the characteristic features of each catalyst were compared and discussed.     

Performance enhancement of air-cooled open cathode polymer electrolyte membrane fuel cell with inserting metal foam in the cathode side

In this study, a novel way to improve performance of the air-cooled open cathode polymer electrolyte membrane fuel cell is introduced. We suggest using a metal foam in the cathode side of the planar unit fuel cell for the solution to conventional problems of the open cathode fuel cell such as excessive water evaporation from the membrane and poor transportation of air. We conduct experiment and the maximum power density of the fuel cell with metal foam increases by 25.1% compared with the conventional fuel cell without metal foam. The open cathode fuel cell with metal foam has smaller ohmic losses and concentration losses. In addition, we prove that the open cathode fuel cell with metal foam prevents excessive water evaporation and membrane drying out phenomena with numerical approach. Finally, we apply the metal foam to the air-cooled open cathode fuel cell stack as well as the planar unit cell.     

Performance improvement of proton exchange membrane fuel cells with compressed nickel foam as flow field structure

In order to improve the performance of proton exchange membrane fuel cell (PEMFC), the compressed nickel foam as flow field structure was applied to the fuel cell. The fuel cell test system was built and the performance of fuel cells with nickel foam flow field with different thicknesses were tested and analyzed by electrochemical active surface area (EASA), electrochemical impedance and polarization curve. And its operating parameters were optimized to improve the performance of PEMFC. Our results show that the membrane electrode assembly (MEA) can show a larger catalytic active area and uniformity of gas diffusion can be improved by using the nickel foam flow field instead of the conventional graphite serpentine flow field, and the impedance characteristic of 110PPI nickel foam can be improved by increasing the compression ratio of the original material. What's more, the polarization characteristic and power output performance of PEMFC with nickel foam flow field were improved by optimizing the operating parameters. Using the optimized operating parameters (cell temperature = 80 °C; humidification temperature = 75 °C; stoichiometric ratio = 2; back pressure = 0.23 Map), a peak power density of 1.89 W cm⁻² was obtained with an output voltage of 0.46 V.     

畜禽场柴油发电机沼气-柴油双燃料转换技术的优化

介绍了将畜禽场柴油发电机转换为沼气-柴油双燃料发电机的基本方法和关键部件的设计要点，提出了更符合内燃机燃烧特性的沼气净化与输配技术措施，使得沼气-柴油双燃料发电机在保持原柴油发电机使用特性的同时，大幅降低柴油的消耗量，取得良好的实际效果。     

Effects of assembling method and force on the performance of proton-exchange membrane fuel cells with metal foam flow field

Recently, highly porous metal foams have been used to replace the traditional open-flow channels to improve gas transport and distribution in the cells. Deformation of flow plate, gas diffusion layer (GDL), and metal foam may occur during assembling. When the cell size is small, the deformation may not be significant. For large area cells, the deformation may become significant to affect the cell performance. In this study, an assembling device that is capable of applying uniform clamping force is built to facilitate fuel cell assembling and alleviate the deformation. A compressing plate that is the same size of the active area is used to apply uniform clamping force before surrounding bolts are fastened. Therefore, bending of the flow plate and deformation of GDL and metal foam can be minimized. Effects of the clamping force on the microstructures of GDL and metal foam, various resistances, pressure drops, and cell performance are investigated. Distribution of the contact pressure between metal foam and GDL is measured by using pressure sensitive films. Field-emission scanning electron microscope is used to observe the microstructures. Electrochemical impedance spectroscopy analysis is used measure resistances. The fuel cell performance is measured by using a fuel cell test system. For the cell design used in this study, the optimum clamping force is found to be 200 kgf. Using this optimum clamping force, the cell performance can be enhanced by 50%, as compared with that of the cell assembled without using clamping plates. With appropriate clamping force, the compression force distribution across the entire cell area can approach uniform. This enables uniform flow distribution and reduces mass transfer resistance. Good contact between GDL and metal foam also lowers the interface resistance. All these factors contribute to the enhanced cell performance.