Affected by the global economic slump and Chinas macro-control policies, the Chinese heavy-duty truck market this year has continued the downward trend last year, registering a sales fall of over 30 percent in the first half. Despite maintaining the upward trend in the first half, the coach market slowed down in the third quarter, showing a dim outlook. Amid concerns, NG vehicles, especially LNG vehicles, have stood out. Both LNG heavy-duty trucks and LNG coaches have seen growth, becoming the biggest highlight in the bleak commercial vehicle market this year. As Chinas leading diesel engine manufacturer, Yuchai Machinery Co., Ltd. (YM) has monopolized the coach industry. Referring to their view of LNG engines, we have recently interviewed Prof. Zhuo Bin, senior technical advisor to chairman of YM and Zhou Chuanwu, assistant to general manager of YM.

Reporter: NG coaches are familiar to people, there were a lot of CNG buses in cities many years ago, but LNG coach is a new thing. What is the difference between LNG engines and CNG engines?

Zhuo: Firstly, LNG and CNG are two different ways of NG storage. Both are composed of methane. CNG is compressed natural gas generally stored in gas cylinders in the form of 200bar high-pressure gas. LNG is liquefied natural gas generally stored in LNG cylinders in the form of liquid at a temperature of 162 Celsius degrees below zero. LNG production is a pure process of physical change and the process is short. Cryogenic technology is used to cool NG to 162 Celsius degrees below zero and liquefy NG under constant pressure. Other heavy components have been removed as floating solid, some gas (e.g. nitrogen) remains in gas state and is collected and emitted. In this way, the components of liquid fuels are all pure alkane, namely methane and ethane. Liquefied NG is transferred to an adiabatic tank for storage.

Secondly, both LNG and CNG as coach fuels. The difference is that LNG better suits coaches due to higher energy density and longer mileage under the condition of same fuel tank volume. Of course, local gas supply is the prerequisite. As fuel gas is conventionally processed into gas before being combusted in the engine in the world, LNG and CNG engines are almost the same. In terms of vehicles, LNG and CNG engines differ in the way of fuel processing, the former turns liquid NG into gaseous NG through gasifiers, and the latter turns high-pressure compressed NG into low-pressure NG through pressure reducers to feed engines.

Lastly, all Yuchais NG engines can use CNG and LNG both. You need to install corresponding fuel processing units only.

Reporter: According to sources, Yuchai commenced gas engine R & D in 1995, accomplished volume matching in 1998 and launched gas engines in large volume in 2000. When did Yuchai launch LNG engines? What are their technical characteristics?

Zhuo: Firstly, Yuchai launched LNG engines in 2006, and Zhanjiangs public transport system inputted 100 LNG buses carrying YC6JN engines for demonstrative operations. Yuchai took the lead in the country to launch bus-specific LNG engines in volume.

Secondly, Yuchai LNG engines are new-generation NG vehicle-specific engines. Prominently, they take full advantage of the large energy density of LNG (roughly three times the energy density of CNG), with a gas-liquid ratio of 625/1 and a long driving range. Having effectively solved the problem of short driving range of CNG vehicles, they are favored by customers.

Lastly, Yuchai LNG engines have eight technical characteristics: 1. Gas quantity is controlled through mainstream international technology--electronic single-point injection; 2. Closed-loop control of air-fuel ratio in the presence of UEGO senor perfectly balances economy and emission; 3. Inter-cooling lean burn ensures high efficiency, energy conservation and clean combustion; 4. Single-cylinder independent high-energy ignition ensures fuel economy; 5. The electronic throttle valve and supercharger bypass control value ensures precise air management; 6. The high-precision sensor ensures the precise measurement and control of the control system; 7. Strong vehicle functions meets various demands of Chinese customers; 8. The perfect fault diagnosis and protection strategy protects the engine and duly clear faults.

The above-mentioned technical characteristics have provided technical guarantee for the outstanding performance of Yuchai LNG engines in power, fuel economy, reliability and environmental protection.

Reporter: Data have shown the number of LNG coaches have soared from less than 100 units to nearly 10,000 units in recent year. Despite fast growth, many transport enterprises are still waiting and some are still making comparison. They want to know if LNG coaches are safe and reliable compared to traditional diesel coaches, how much fuel cost will be saved and if future maintenance cost is high. Could you answer these questions?

Zhuo: Firstly, the advantages of LNG vehicles include:

1. Good economy: as vehicle fuel, LNGs value has multiplied compared to oil fuel (diesel or gasoline).

2. High environmental value: LNG has high purity and contains no harmful substances like HS. LNG engines discharge few exhaust pollutants, making LNG a clean and quality fuel.

3. Long driving range: LNG has high density and is one 625ths of gaseous NG in volume, which increases fuel inventory and driving range.

4. High safety: LNG has low storage pressure of only 1.3Mpa, far lower than CNG with 20Mpa.

5. Low cost of station building: LNG stations have little equipment, cover small area, and can be built separately or be compatible with existing gas stations to reduce the building cost of LNG stations.

6. Easy popularization: LNG is transported by tank cars without the need to lay pipelines; the noise of charging is small, LNG stations can be built in densely-populated downtowns to easily form charging networks.

Secondly, LNG vehicles are safer compared to diesel coaches:

1. LNG is a safe fuel itself. Its safety is reflected in: a) High ignition point. NG ignition point is at over 650 degrees and is not easy to ignite. B) Low density. NG is lighter than air and its density is only 55 percent of air. Leaked NG is easy to diffuse in the air and difficult to burn in case of fire. C) Narrow explosion limit. The explosion limit is only 5 percent to 15 percent, and it is difficult to form the condition in natural environment. D) As low-temperature liquid, LNG is gasified quickly in case of leakage, the latent heat of LNG gasification is sufficient to make the ambient temperature of gas drop sharply. Besides, as gas density is lower than air density, gas diffuses easily in the air and is not prone to combustion and explosion. E) Odorant is generally added to NG to find NG gas early.

2. Anti-overpressure safety values, as well as anti-leakage restrictor valves and emergency cut-off valves are set in LNG storage banks and pipelines against and leakage. The State has promulgated the rigorous technical standards for NG vehicles. Rigorous technical standards have formed in every link from gas station design, gas cylinder production, to manufacture, installation and commissioning of parts of modified vehicles.

3. Therefore, the safety of LNG coaches is not inferior to diesel coaches.

Thirdly, reliability. With the massive development of the LNG industry and the speedup of gas vehicle popularization worldwide, and the acceleration in LNG vehicle technology researches in different countries, on the basis of the mature technologies of CNG engines, China has thoroughly solved problems including the adiabatic technology of LNG storage tanks and the reliability of some low-temperature valves including electromagnetic valve and shutoff valve, by introducing mature LNG vehicle technologies and equipment from abroad and relying on technical forces in the domestic low-temperature industry. Due to reliable quality, LNG engines have entered the stage of massive application in China.

Fourthly, how much fuel cost is saved?

1. According to statistics on actual bus operations, an average 1.32m3 NG can replace 1L diesel. Therefore, when LNG prices are less than 75 percent of diesel prices, using LNG can save operating cost. When LNG prices or engine gas consumption are lower, more cost will be saved.

2. If diesel is priced at 7 yuan/L and NG at 4 yuan/m3 in an eastern city, using NG on buses will save fuel cost by 25 percent. If diesel is priced at some 2 yuan/m3 in a western city, fuel cost will be saved considerably by over 60 percent. (The data above taken no account of government fuel subsidies)

Lastly, future maintenance cost.

All NG vehicle engines will be designed specifically. Aiming at problems including lubrication and high temperature, improvements have been made to parts including piston friction pair, valve and supercharger. Therefore, Yuchai NG engines are as reliable as diesel engines. Combined with considerate after-sale training and service, customers can use Yuchai NG engines without worry. Compared to diesel engines, some maintenance cost will be incurred from wearing parts of gas engines including spark plug and high-pressure wire, and the maintenance of the gas system. Overall, the future maintenance cost of NG engines is slightly higher than that of diesel engines. However, it is economical in view of saved fuel cost.

Reporter: According to sources, Yuchai holds a share of 41.7 percent in the NG engine market, ranking first in the industry; held the LNG coach coach market in 2011. In the NG engine field, how did Yuchai achieve brilliant results in the face of fierce competition from high-end foreign brands and domestic peers?

Zhou: there are four reasons for Yuchais brilliant results in the NG market:

I Yuchais coach engine brand strategy: Yuchai has held the largest share of over 60 percent in the coach industry for 11 years in a row, the market and customers highly recognize Yuchai coach engine brands, and the specialization and adaptability of Yuchai coach engines have enjoyed good reputation in the industry.

2. Yuchais leading NG coach engine technology: Yuchai commenced gas engine R & D in 1995, accomplished volume matching in 1998 and launched gas engines in large volume in 2000. After over ten years of technical R & D and market validation, Yuchai NG technologies have pulled ahead in the industry. As the core representatives of Yuchai NG technologies, single-point injection and lean burn have boosted power and fuel economy. Based on market needs, Yuchai has developed NG engines, using specific parts massively to boost product stability in high-temperature combustion. Additionally, Yuchai has taken the lead to develop independent systems and National V gas engines in the industry. These leading technologies have further consolidated Yuchais lead in the coach industry.

3. Yuchais complete NG engine spectrum: Just like Yuchai coach engines, Yuchai has a wide product chain in the NG market and provide multiple models for customer choice. Yuchai NG engines have covered original diesel vehicles and been able to provide adaptive engines to customers in market segments.

4. Yuchais strong service support: Yuchais service network is huge and perfect, and can provide professional and timely service support for NG engines. Besides, Yuchai has not only proposed that gas engines may enjoy the same warranty policies as diesel engines enjoy in the industry, but also provided corresponding technical support and professional training to customers, thus truly ensuring after-sale services for customers.

Reporter: How many Yuchai LNG engines have been installed to date? Which brands? Which models?

Zhou: Yuchai mainly supplies LNG engines to all domestic major coach manufactures including King Long, Higer, Golden Dragon, Yutong, Hengtong, Ankai and Huanghai to match buses and coaches ranging from 7 meters to 12 meters. 20,000 Yuchai NG coach engines are expected to be available in 2012.

Reporter: According to sources, up to 450,000 LNG buses are available in the world, and 200,000 LNG buses are expected to be available in China by the end of the twelfth five-year period. Do you think such substantial growth is expectable in a short span of three or four years? How much of such an alluring big cake will Yuchai share?

Zhou: Due to the impact of two major factors-oil-gas price difference and environmental pressure, the domestic NG coach market has grown rapidly in recent years, especially in the coastal area. We expect NG coaches to maintain rapid growth over the next few years. Yuchai will strive to provide outstanding NG engines and fast after-sale services to the NG coach market, and remain as the navigator of the Chinese NG coach engine market.

(Source: Huang Lili/chinabus.info)