数控气动发动机动力系统设计

数控气动发动机以压缩空气或液氮为动力源,通过其膨胀做功,将压力能转化为机械能.该文根据气动发动机的特点,对其能量供给系统、做功系统及控制系统进行了研究.分析了气动发动机动力源与气动发动机之间的高压气体减压控制过程及气动系统能量变化的特性,在能量的供给系统中加入客积减压和定量预喷系统,提出了新型数控气动发动机动力系统的设计方案.     

压缩空气发动机发展综述

压缩空气发动机是利用高压压缩空气工作,将高压空气中储存的压缩能转换其它的机械能的一种动力装置.在资源和环境问题日益突出的情况下,压缩空气发动机与传统的发动机相比具有诸多优点,因而在车辆、发电装置、航空等方面得到越来越多的应用,在国外已成为节约能源和治理环境污染的重要途径之一.国内外研究的压缩空气发动机主要有往复式、叶片式、旋转式三种结构形式.对这三类发动机的工作基本原理和结构特点进行了分析比较,得出各自的优缺点和将来研究的重点,并展望了新型旋转式压缩空气发动机技术.通过分析国内外压缩空气发动机的研究进展,从六个方面总结出提高压缩空气发动机效率和经济性的途径.     

压缩空气动力发动机的仿真与研究

介绍了压缩空气发动机的工作原理,分析了利用压缩空气发动机作为汽车动力的可行性。对其中一种往复式活塞压缩空气发动机进行了建模分析,在MATLAB中进行相应模拟,得出进气压力、温度、发动机转速对于压缩空气发动机性能的影响。仿真结果表明,进气压力的提高使得发动机性能近乎线性提高,进气温度的提高也可以提高发动机性能。最后分析了使用压缩空气发动机作为混合动力汽车动力源的可能性。鉴于压缩空气发动机的节能环保优势及可靠的动力输出,其可以代替电动机而应用于混合动力汽车。     

液氮发动机配气装置的原理与实验研究

液氮发动机的供气能力决定着它的工作效率,为了提供液氮发动机工作所需要的充足、稳定的高压气体,设计了一种应用于液氮发动机的配气装置,该装置由液氮存储设备、低温泵、换热器及配气筒组成,该装置将低温液氮通过换热器汽化成高压氮气,提供液氮发动机的正常工作所需的高压气体.对配气装置的原理和热力过程进行研究,并通过实验对换热器性能进行测验和分析,通过实验研究发现该装置供气稳定,出口压力和进出口压力差都能满足液氮发动机正常的工作需要.     

压缩空气/燃油混合动力发动机热力学分析

提出了一种压缩空气/燃油混合动力发动机概念,该发动机可以在压缩空气动力和内燃机两种模式下运行。运用理想热力循环理论建立了混合动力发动机两种工作模式的数学模型,并对平均指示压力及其他重要性能指标进行了仿真研究。仿真结果表明,两种工作模式下发动机的平均指示压力等主要性能指标与传统内燃机相近,而且能够实现两种工作模式的平稳切换,这说明压缩空气/燃油混合动力发动机是可行的,并能够达到节约燃油、减少尾气污染排放的目的。     

压缩空气/燃油混合动力发动机工作过程可用能分析

以一种新型压缩空气/燃油混合动力发动机作为研究对象,应用热力学第二定律建立了该混合动力发动机两种工作模式--压缩空气动力模式和内燃机模式的可用能平衡数学模型,并对其工作过程的可用能分布进行了仿真研究.仿真结果表明,压缩空气动力模式的减压和排气过程可用能损失之和超过了50%,降低减压损失和回收排气可用能是提高压缩空气能效的主要途径;内燃机模式的排气可用能损失达到了20.2%,采用废气能量回收措施能够显著提高发动机效率.     

压缩空气/燃油混合动力发动机工作过程可用能分析

以一种新型压缩空气/燃油混合动力发动机作为研究对象,应用热力学第二定律建立了该混合动力发动机两种工作模式——压缩空气动力模式和内燃机模式的可用能平衡数学模型,并对其工作过程的可用能分布进行了仿真研究。仿真结果表明,压缩空气动力模式的减压和排气过程可用能损失之和超过了50%,降低减压损失和回收排气可用能是提高压缩空气能效的主要途径;内燃机模式的排气可用能损失达到了202%,采用废气能量回收措施能够显著提高发动机效率。     

气动发动机设计方法与理论的研究进展

气动发动机是一种以压缩空气为动力源的新型发动机,其绿色环保特点十分突出,具有广阔的市场前景。气动发动机的设计难点是提高压缩空气储能利用率,进而改善其性能。阐述了近年来气动发动机的主要设计方法,分析了各种设计方法和理论的不同点,比较了在提高气动发动机效率上的各自优点和不足,对气动发动机设计方法和理论研究所呈现的主要特点进行了总结和展望,提出了以多学科组合优化方法进行气动发动机效率提升途径研究的发展方向。     

压缩空气动力汽车的可行性分析

介绍了压缩空气动力汽车的工作原理,研究了空气动力发动机工作过程的能量利用,对高压空气的储存压力进行选取,并分析了环境温度、行驶速度、汽车总质量等因素对空气动力汽车续驶里程的影响,探讨了空气动力汽车的补充能源来源、经济性、安全性、结构布置等问题,认为压缩空气动力汽车在技术上是可行的,是一种具有应用前景的绿色汽车。     

一种降低车辆能耗的方法及其装置

本发明公开了一种降低车辆能耗的方法及其装置，涉及车辆及发动机。把空气压缩机或罐装压缩空气通过其储气罐输出气阀门、管道与一台转换压缩空气内能为机械能的二过程发动机进气岐管连接，在输出气阀门至二过程发动机的气缸之间设置可导入大气给该发动机气缸的阀门，组成一种原从动发动机动力装置，把二过程发动机的动力输出轴与车辆驱动轮的传动装置动力连接，由驾驶员操控输出气阀门释放压缩空气量而控制该二过程发动机输出功率大小驱动车辆行驶。可同时利用无用功和或外来能量来参与作功。     

液态空气驱动的半开半闭循环发动机

由于液态空气的低温和压缩特性,其储存的能量包含冷能、膨胀能。能量的组成和数量与气化压力的大小有关。过去的全开环气动发动机仅仅利用了膨胀能,而忽略了冷能,这导致发动机效率低。液态空气驱动的半开半闭循环发动机,充分利用膨胀能和冷能来提高效率。开环和闭环的权重比是影响发动机效率的一个重要因素。     

热空气注入式液氮能量转换装置效率分析

液化空气储能是指在电网负荷低谷期将电能用于压缩空气成液态,在电网负荷高峰期释放液化空气气化推动汽轮机发电的储能方式。由于液态空气的低温特性和压缩特性,其储存的能量包含冷能和膨胀能两部分能量。能量的组成和数量与气化压力p0有关。过去的液空能量转换装置仅仅利用了膨胀能,而忽略了冷能,这导致了其效率低下。热空气注入式能量转换装置提出了通过回收低温冷能提高发动机的效率。理论效率可以通过提高工作压力来提高。最后提出了寻求一个有效的方法同时利用膨胀能和冷能来提高液态空气储能系统的效率为未来液态空气储能研究的趋势。     

液压自由活塞发动机动态特性的仿真研究

液压自由活塞发动机(hydrau lic free p iston engine,以下简称HFPE)是将内燃机和液压泵集成为一体,以液体为工作介质实现动力非刚性传输的一种特种发动机。在左、右动力腔的交替驱动下,HFPE的活塞组件在腔体中作往复直线运动,同时泵出液压油驱动负载工作。与曲轴式发动机不同,由于不受曲柄连杆机构的约束,HFPE活塞组件的运动规律完全取决于其本身的质量及所受到的作用力。本文通过建立所研制的HFPE样机各子系统的数学模型,重点研究了HFPE样机的动态特性,以期为系统的结构及控制系统提供理论依据。     

An investigation on the performance of a Brayton cycle waste heat recovery system for turbocharged diesel engines

A Brayton cycle waste heat recovery (WHR) system for turbocharged diesel engines was proposed and the performance of a diesel engine integrated with the proposed system was investigated. The waste heat recovery system is integrated with the turbocharging system of diesel engines, using the turbocharger compressor as the Brayton cycle compressor. The engine cycle simulation code GT-Suite 7.0 was used to investigate the performance of a diesel engine integrated with the WHR system. A Brayton cycle turbine was designed and its performance was simulated with a through-flow model. The turbocharging system of the original engine was modified and the energy flow distribution between the diesel cycle and the Brayton cycle was optimized. Results show that the fuel economy of the diesel engine can be improved by 2.6% at high engine speed and 4.6% at low engine speed under engine full load operating conditions when equipped with the Brayton cycle WHR system. The influence of turbocharger parameters on the WHR engine performance was invesgated.     

Development of an evaporative cooling system for small four-stroke engines

A new evaporative cooling system for small four-stroke engines has been developed. Performance tests of a four-stoke single cylinder engine equipped with this evaporative cooling system have been carried out in the laboratory. Air removal rates from the closed coolant loop during the starting stage of the engine have been monitored for various engine operating conditions. In addition, data of the brake horsepower, the specific fuel consumption, heat loss to the coolant, cylinder-liner wall temperature and the wall heat flux have been obtained and were compared to those of the identical engine equipped with a conventional liquid cooling system. At a fixed air fuel ratio and under the MBT condition, the brake horsepower of the engine for the evaporative cooling system is enhanced compared to that for the liquid cooling system. The heat loss through the cylinder liner is decreased when the evaporative cooling system is adopted. The test result indicates several benefits of the evaporative cooling system such as faster warm up, better fuel economy and greater engine durability.     

两相脉冲爆震发动机混合流动特性的数值模拟

脉冲爆震发动机具有众多优点,近来受到广泛的关注和研究。要成功起始爆震首先要解决燃油、空气的喷射与混合问题。本文利用CFD程序分别对切向、轴向和径向供气方式的混合室中油、气的混合流动特性进行了三维数值模拟,结果显示三种供气方式各有优劣。切向进气有助于油气的充分混合,但是油、气分布不均,不利于发动机的高频工作;轴向进气时油、气分布比较均匀,但是油气的混合不够充分,增加发动机爆燃向爆震转变的难度;而径向进气的油气分布、混合程度介于切向与轴向进气之间,能耗较大。     

基于高能量转换效率的旋转式气动发动机动力学分析

针对目前常用气动发动机能量转换效率低的现状,提出一种新型旋转凸轮活塞式气动发动机结构。根据气动发动机工作原理,针对旋转式气动发动机膨胀容积大,缸内高压气体压力直接推动凸轮活塞旋转对外做功的结构特点,分析缸内气体压力与输出扭矩之间的关系,建立动力学模型,并以此动力学模型为基础,利用Matlab/Simulink软件对该发动机单缸工作过程进行计算机仿真分析。仿真结果表明:旋转式气动发动机具有低速时有效扭矩大,能量转换效率高的优点。     

全寿命周期发动机大修成本优化研究

当前情况下,伴随着我国经济社会的不断发展,许多发动机在实际维修以及后续检修过程中,经常会出现许多技术操作问题以及设备故障问题,为了进一步提升发动机全寿命周期检测工作,以及后续设备维护工作的实际效率,必须要认真研究全寿命周期发动机大修的具体成本数额,以及相关的成本构成。因此,笔者将在文章以下内容中,结合发动机大修的具体成本构成,认真分析发动机全寿命周期维修与维护的具体方法。     

A study on the usability of biodiesel fuel derived from rice bran oil as an alternative fuel for IDI diesel engine

The world is faced with a problem of air pollution due to the exhaust emissions from automobile. Recently, lots of researchers have been attracted to develope various alternative fuels and to use renewable fuels as a solution of these problems. There are many alternative fuels studied in place of diesel fuel made from petroleum. Biodiesel fuel (BDF) is a domestically produced, renewable fuel that can be manufactured from vegetable oils, used vegetable oils, or animal fats. In this study, the usability of BDF, one of the oxygenated fuels as an alternative fuel for diesel engines was investigated in an IDI diesel engine. Emissions were characterized with a neat BDF and with a blend of BDF and conventional diesel fuel. Since the BDF includes oxygen of about 11%, it could influence the combustion process strongly. Therefore, the use of BDF resulted in lower emissions of carbon monoxide and smoke emissions with some increase in emissions of oxides of nitrogen. It is concluded that BDF can be utilized effectively as a renewable fuel for IDI diesel engines.     

Performance and combustion characteristics of a diesel engine with titanium oxide coated piston using Pongamia methyl ester

Owing to the increasing cost of petroleum products, fast depletion of fossil fuel, environmental consideration and stringent emission norms, it is necessary to search for alternative fuels for diesel engines. The alternative fuel can be produced from materials available within the country. Though the vegetable oils can be fuelled for diesel engines, their high viscosities and low volatilities have led to the investigation of its various derivatives such as monoesters, known as bio diesel. It is derived from triglycerides (vegetable oil and animal fates) by transesterification process. It is biodegradable and renewable in nature. Biodiesel can be used more efficiently in semi adiabatic engines (Semi LHR), in which the temperature of the combustion chamber is increased by thermal barrier coating on the piston crown. In this study, the piston crown was coated with ceramic material (TiO₂) of about 0.5 mm, by plasma spray method. In this present work, the experiments were carried out with of Pongamia oil methyl (PME) ester and diesel blends (B20 & B100) in a four stroke direct injection diesel engine with and without coated piston at different load conditions. The results revealed 100% bio diesel, an improvement in brake thermal efficiency (BTE) and the brake specific fuel consumption decreased by about 10 % at full load. The exhaust emissions like carbon monoxide (CO) and hydrocarbon (HC) were decreased and the nitrogen oxide (NO) emission increased by 15% with coated engine compared with the uncoated engine with diesel fuel. The peak pressure and heat release rate were increased for the coated engine compared with the standard engine.