汽车论文摘要

汽车论文摘要

摘 要：本文阐述了发展压缩天然气汽车(CNG)的环保低污染性、安全性、经济性及CNG汽车和加气站的发展前景及对策。

关键词：压缩天然气汽车；加气站；发展前景；对策

目前，我国一些大城市的汽车尾气排放是城市大气污染的主要源头，因此，发展清洁能源汽车已成为刻不容缓的的选择。压缩天然气汽车(CNG)以其能耗低、污染物排放量小而受到各国的欢迎，是国际公认的最理想的车用替代能源。发展天然气汽车对于解决环境问题和能源问题都具有重要意义。

一、天然气汽车的发展情况

l、国外天然气汽车发展概况

为保护环境减少污染，许多国家政府颁布了一系列法规及出台一些鼓励性政策，促进燃气汽车发展，如制定更严格的汽车尾气排放标准，在天然气供应、汽车购置税费，设备供给、加气站建设等方面给予资金、税收优惠政策。

美国联邦政府1992年颁布的《能源政策法》，对于购买或改装代用燃料汽车及加气站的建设减免税作出详细规定，同时还颁布了使用天然气的减税政策，并免征天然气公司的汽车燃料销售税。有40多个州根据联邦政府的政策、法律，制定了本州有关强制和鼓励使用CNG等清洁燃料汽车的政策和措施，推动了CNG汽车发展和加气站建设。目前，全世界已有40多个国家拥有燃气汽车，主要分布在天然气资源丰富的意大利、新西兰、阿根廷、巴西等国家和环保法规严格的美国、日本等国。

2、我国天然气汽车发展概况

20世纪80年代中期，我国引进了部分CNG加气站设备，在四川建立了我国第一个CNG加气站；1993年中国石油天然气总公司系统引进国外有关技术并于 1996年将加气站装置和汽车改装部件引进技术国产化、技术标准规范化。1999年全国清洁汽车行动协调领导小组成立，启动了北京、天津、上海、西安、深圳等12个试点城市地区的清洁能源推广应用工作，在CNG汽车的推广应用和加气站建设方面取得了前所未有的成效。根据有关部门统计数字，截止到2004年我国一些地区共有天然气汽车20多万辆，加气站700多座。

二、天然气汽车(CNG)与其它燃料的环境、经济效益比较

压缩天然气汽车：

天然气压缩至20MPa于汽车用压缩天然气钢瓶中，经减压器后供给内燃机。

以CNG作汽车燃料与汽油相比具有以下优点：

l、降低污染，改善大气环境：天然气是一种清洁能源，具有热值高、效率高、污染小等特点，燃烧比较完全，不易积碳，CO、NOx和微粒的排放量均低于汽油，排气污染明显降低。机动车尾气是城市大气污染主要来源之一，其中主要有害成分是一氧化碳(C0)、碳氢化合物(HC)、一氧化氮(N0)和二氧化氮 (NO2)等。据有关资料显示，使用天然气作为汽车燃料与汽油作燃料相比可以减少排放90％CO、90％S02、72％HC、39％NOx、 24％CO2、无粉尘排放，对改善城市环境有显著作用。典型的柴油机与汽油机及天然气机排放情况比较见表l。

2、CNG汽车有较高的安全性

与汽油相比，压缩天然气是相对安全的燃料。

(1) 天然气爆炸下限为5％，比汽油(爆炸下限为l％)高，甲烷燃点为645℃ ，比汽油燃点高218℃，相比不易点燃。甲烷密度低，相对密度为0．55左右，泄漏的气体很快会在空气中散发，在自然环境中难以形成遇火爆燃的条件，一旦压缩天然气从储罐或管路中泄漏，泄漏点周围会立即形成低温区，使天然气燃烧困难。因此CNG是一种相当安全的汽车燃料。天然气与汽油的燃料特性比较见表2

(2)天然气汽车的钢瓶系高压容器

(20MPa)，其材质及制造、检验试验在各国均有严格的规程控制，在我国有《汽车用压缩天然气钢瓶标准))(GBl7258—1998)。

钢瓶安装有防爆设施，减压器、阀门等设备，严密度标准高，供气系统安全可靠，不会因汽车碰撞或翻覆造成失火或爆炸，而汽油汽车的油箱系非压力容器，着火后容易爆炸。

3、有利于缓解能源紧张的供需矛盾。

我国经济正处于高速发展阶段，汽车数量以100万辆／年以上的速度递增，对汽油资源需求大量增加，我国每年需要进口大量原油、成品油和LPG。使用燃气汽车可优化

汽车燃料供应结构，改变了汽车燃料只有汽油、柴油的格局，既缓解了汽油供应紧张的问题又满足交通事业发展的需要。

4、可延长发动机寿命。天然气容易扩散，以气态进入发动机，在发动机中容易和空气均匀混合，燃烧比较完全、干净；可以提高热循环效率，加快燃烧速度，充分利用燃烧热能；同时CNG辛烷值高，抗暴性能好，使用时不需要添加抗暴剂，不会稀释润滑油，因而使发动机气缸内的零件磨损大大减少，使发动机的寿命和润滑油的使用期限大幅度增长。所有这些都会降低汽车的保养和运行费用，从而提高汽车使用的经济性。 5、有较高的经济效益。目前，国内汽油价格持续上升，价格体系已和世界接轨，使用CNG汽车将能节省近40％燃料费用，见表3。

三、CNG汽车的发展前景

CNG汽车和加气站具有广阔的发展前景，主要表现在以下几方面：

l、汽车保有量的飞速增长、石油资源和环保的严峻形势，决定了发展天然气汽车成为解决能源问题和环境问题的重要途径。

2、“十一五”期间，新型清洁能源汽车已被列入《国家科技发展中长期规划》，国家将继续组织实施涉及各种清洁能源汽车的重大科技项目，重点支持包括天然气汽车在内的整车、零部件等关键技术，将进一步促进天然气汽车的发展。

3、我国天然气资源大规模开发及管道建设步伐加快使发展CNG和加气站成为可能。根据我国天然气利用规划，近十年“西气东输”、“陕京二线”等一大批输气管道及沿线城市燃气管道相继建成，我国大规模利用天然气的基础设施逐步完善，天然气加气站也将逐步形成网络。

4、发展CNG汽车具有稳定的气源保证，以天津为例，目前天津市已建立了完善的天然气输配系统，由陕北、大港、华北等油田向天津供气，2005年年供气量近6 亿m3，2006年预计达8亿m3，管网长度6894km，其中，高压管线591km，为“十一五”期间天津市大力发展CNG汽车大规模建设加气站提供了保证。

四、CNG汽车和加气站发展对策探讨

为加快以天然气为燃料的清洁汽车的发展，提出以下建议：

1、政府出台鼓励和扶持政策：世界各国发展经验表明，政府的支持是加快发展的必要条件，其经济政策是影响其发展的重要因素，应在法律方面予以保障，在燃气汽车生产、改装、零部件生产，加气站建设，燃气汽车购买和使用、维修等环节制定价格、税收、投资、补贴等方面配套的优惠政策。燃气价格是影响燃气汽车发展的重要因素，只有燃气价格与汽油价格形成足够大差价时，燃气汽车的发展才具有经济基础和推动力。

2、加强领导，实行统一管理。发展CNG汽车必须建设优质、便利的加气站，需要规划、公安、消防、劳动、技监等部门的支持。

3、在市政规划中，加气站与加油站应统筹考虑，合理布局，协调发展。尽量利用现有土地资源，在确保环境安全的前提下建设油气合一站。

4、遵循CNG汽车与加气站同步发展的原则，只有在加气站成网的条件下，CNG汽车才能真正发展。同时也只有CNG汽车规模到了一定数量，加气站才能正常运转，实现盈利。

5、严格法律制度：制定严格的汽车尾气排放法规，切实做到不达标车辆坚决不予以上路，对CNG汽车改装厂的资格进行严格审查，认证。首先应将城市城市公交车、出租汽车作为CNG汽车发展的重点，杜绝部分公交车冒黑烟污染环境的现象。

6、加大宣传力度。目前，天然气汽车尚处于起步阶段，社会公众对它的环保性，安全性，经济性，可靠性还不充分了解，所以，要进行广泛的社会宣传，努力提高人们对汽车尾气危害性的认识，使人们了解CNG是清洁、安全、经济的车用燃料，使发展天然气汽车得到社会各方面的认可和支持。

压缩天然气汽车由于其显著的经济效益和社会效益将成为天然气市场开发应用的一个新领域。在环境保护越来越受到重视的形势下，随着天然气资源的开发和应用领域的拓宽，此举将是减轻环境污染压力、缓解石油紧缺，实现可持续发展的可靠保证。

Abstract: This paper describes the development of compressed natural gas vehicles (CNG) on environmental protection of low-pollution, security, economic and CNG cars and filling stations and prospects for the development of countermeasures.

Key words: compressed natural gas vehicles; stations; development prospects; Countermeasures

At present, China's major cities is a urban vehicle emissions a major source of air pollution, therefore, the development of clean energy vehicles have become the choice of the delay. Compressed natural gas vehicles (CNG) in their low energy consumption and emissions by all countries small and welcoming, is recognized internationally as the best alternative energy vehicle. The development of natural gas vehicle to address the environmental issues and energy issues are of great significance.

First, the development of natural gas vehicle

l, development of foreign natural gas vehicle

Reduce pollution to protect the environment, many countries have issued a series of government regulations and the introduction of a number of incentive policies to promote the development of gas vehicle, such as the development of more stringent vehicle emission standards, in the natural gas supply, car purchase taxes and fees, equipment supply, gas station construction grant funds, tax incentives.

In 1992 the U.S. federal government enacted the "Energy Policy Act," or modified for the purchase of alternative fuel vehicles and the construction of stations in detail the provisions of the tax relief, but also enacted a tax cut that the use of natural gas and natural gas companies exempt from motor vehicle fuel sales tax. There are more than 40 states in accordance with the policy of the federal government, law, drawn up on the mandatory state and encourage the use of clean fuel CNG vehicles, such as policies and measures to promote the CNG filling station development and construction of motor vehicles. At present, more than 40 countries around the world have a gas car, mainly in the rich natural gas resources in Italy, New Zealand, Argentina, Brazil and other countries and stricter environmental regulations the United States, Japan and other countries.

2, China's Natural Gas Vehicle Development

80 In the mid-20th century, the introduction of some of our CNG filling station equipment, set up in Sichuan's first CNG filling stations in China; in 1993 the China National Petroleum Corporation on the introduction of foreign technology systems in 1996 installations and will be filling stations modified car parts made of the introduction of technology, standardization of technical standards. 1999 National Clean Automobile Action Coordination Leading Group was established to start the Beijing, Tianjin, Shanghai, Xi'an, Shenzhen and other cities in 12 pilot areas to promote the application of clean energy in the popularization and application of CNG vehicles and filling stations has made an unprecedented building results. According to relevant statistics, as of 2004 there were some areas of China's natural gas vehicle more than 20 million vehicles, more than 700 filling stations Block.

Second, natural gas vehicle (CNG) fuel and other environmental and economic benefits compared

Compressed natural gas vehicles:

20MPa compressed natural gas in the car to compressed natural gas cylinders in use by the supply of internal combustion engine after the pressure reducer.

To CNG fuel for vehicles compared with gasoline has the following advantages:

l, reduce pollution and improve the atmospheric environment: natural gas is a clean energy, with a high calorific value, high efficiency, pollution, etc., the comparison is totally burned, not carbon deposition, CO, NOx and particulate emissions than gasoline, significantly reduced exhaust pollution. Motor vehicle exhaust is the major source of urban air pollution, one of which is carbon monoxide harmful ingredients (C0), hydrocarbons (HC), nitric oxide (N0) and nitrogen dioxide (NO2) and so on. According to the data, the use of gas as a motor fuel and gasoline as fuel can reduce emissions compared to 90% CO, 90% S02, 72% HC, 39% NOx, 24% CO2, non-dust emissions, to improve the urban environment has a significant role in . A typical diesel engine and gasoline engine emissions and gas machine is shown in table l.

2, CNG vehicle for a higher security

Compared with gasoline, compressed natural gas is a relatively safe fuel.

(1) natural gas explosion limit is 5% higher than gasoline (lower explosion limit for the l%) high, methane ignition for 645 ℃, ignition than gasoline high 218 ℃, compared to not ignite. Low density of methane, the relative density of about 0.55, resulting in leakage of gas will soon be distributed in the air, in the case of the natural environment it is difficult to form a hot combustion conditions, once the compressed natural gas from the tank or pipe leaks, leak immediately surrounding the formation of low-temperature zone, so that the difficulties of natural gas combustion. Therefore is a fairly safe CNG motor fuel. Natural gas and fuel properties of gasoline is shown in table 2

(2) Department of natural gas vehicle cylinder pressure vessel

(20MPa), its materials and manufacture and testing in order that all States have strict control, in China there are "compressed natural gas cylinder vehicle standards)) (GBl7258-1998).

Cylinders fitted with explosion-proof facilities, pressure reducer, valves and other equipment, strict standards high, and gas supply system is safe and reliable and will not tip over due to vehicle collision or cause fire or explosion, and the petrol tank of motor vehicles department of non-pressure vessels, fire easily after the explosion.

3, will help ease the contradiction between energy supply and demand tension.

China's economy is in a stage of rapid development, the number of vehicles to 1 million / year above the rate of increase of a substantial increase in gasoline demand of resources, our need to import large quantities of crude oil per year, refined oil and LPG. Optimize the use of gas cars

Motor fuel supply structure has changed only motor fuel gasoline, diesel patterns, not only eased the problem of shortage of petrol and transport services to meet the needs of the development.

4, extend engine life. The spread of natural gas to the gas entering the engine, the engine easily and uniformly mixed air, burning the comparison is totally clean; can improve the thermal cycle efficiency, speed up the burning speed, full use of combustion heat; CNG octane number at the same time high performance uprising, when agents do not need to add the uprising will not dilute the lubricating oil, making the parts inside the engine cylinder greatly reduce wear and tear, so that the engine oil life and increase the use of the period. All of these vehicles will reduce maintenance and operating costs, thereby enhancing the economy of the use of vehicles. 5, have a higher economic efficiency. At present, domestic gasoline prices continued to rise, the price system and the world has been the use of CNG vehicle will be able to save nearly 40% of fuel costs, as shown in table 3.

Third, CNG vehicle development prospects

CNG cars and filling stations will have broad prospects for development, mainly in the following aspects:

l, cars of the rapid growth of oil resources and environmental protection, the grim situation, the decision of the development of natural gas vehicles as a solution to energy issues and environmental issues an important way.

2, "Eleventh Five-Year" period, a new type of clean energy vehicles have been included in "long-term national science and technology development planning", the state will continue to organize and implement a variety of clean energy vehicles of major scientific and technological projects, the focus of support, including natural gas vehicles, including vehicles, parts, etc., will further promote the development of natural gas vehicle.

3, large-scale development of China's natural gas resources and pipeline construction to accelerate the pace of development of CNG and LPG filling stations make it possible. According to China's natural gas use planning, for nearly a decade, "West-East Gas Transmission", "second Shaanxi-Beijing", such as a large number of gas pipeline and gas pipeline along the cities have built large-scale use of natural gas in China's gradual improvement of infrastructure, natural gas filling stations will gradually form a network.

4, the development of CNG auto gas source with the stability of assurance to Tianjin as an example, at present, Tianjin has established a perfect system of natural gas transmission and distribution, from northern Shaanxi, Dagang, Tianjin, North China Oil Field to supply, gas supply is nearly mid-2005 600 million m3, 2006 was projected to reach 800 million m3, the length of pipe network 6894km, of which high-pressure pipeline 591km, for the "Eleventh Five-Year" period of Tianjin to develop large-scale construction of CNG filling stations car provides a guarantee.

Fourth, CNG cars and filling stations to explore the development of countermeasures

In order to speed up the use of natural gas as a clean fuel vehicle development, makes the following recommendations:

1, the Government has introduced policies to encourage and support: the development of all countries in the world experience shows that government support is a necessary condition for accelerated development, the impact of its economic policy is an important factor in their development should be guaranteed in law, in the gas automobile production, modification, parts and components production, station construction, vehicle purchase and use of gas, maintenance and other aspects of pricing, taxation, investment, subsidies and other aspects of the preferential policies supporting. Gas prices affect gas vehicle development is an important factor, only the gas prices and gasoline prices when the difference is large enough to form, gas car before the development of an economic foundation and driving force.

2, strengthen leadership, the implementation of unified management.

The development of CNG vehicles to the construction of high-quality, convenient filling stations, the need for planning, public security, fire safety, labor, technical support supervisor and other departments.

3, in the municipal plan, filling stations and gas stations should be considered co-ordination, rational distribution and coordinated development. To make full use of existing land resources and in ensuring the environmental safety of oil and gas under the premise of building one station.

4, followed by motor cars and CNG filling stations in the simultaneous development of the principles, only in the stations into a network under the conditions, CNG vehicle can really develop. At the same time scale of only CNG car to a certain number, the normal operation of filling stations in order to achieve profitability.

5, the strict legal system: the development of stringent vehicle emissions regulations, and make sure that standards are not road vehicles are determined not to be on the qualifications of CNG vehicle Modify-Factroy critical examination, certification. First of all, the city should the city bus, taxi, as the focus of the development of CNG vehicle, bus stop some of the phenomenon of black smoke pollution of the environment.

6, step up publicity. At present, natural gas car is still at the initial stage, the public nature of its environmental protection, safety, economy, reliability, do not fully understand, so, it is necessary to carry out a wide range of social advocacy, efforts to increase awareness of the dangers of automobile exhaust, to make people aware of CNG is a clean, safe and economical fuel, so that the development of natural gas vehicles have been recognized by all sectors of society and support.

Compressed natural gas vehicles because of its remarkable economic and social benefits the development of the natural gas market will become a new field of applications. More and more importance in the environmental protection situation, along with natural gas resources in the area of the development and application of the widening, which will reduce the environmental pressure is to ease the oil shortage and achieve sustainable development of a reliable guarantee.

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