| IMPACT OF NATURAL GAS FUEL CHARACTERISTICS ON
THE DESIGN AND COMBUSTION PERFORMANCE OF
A NEW LIGHT-DUTY CNG ENGINE |
| Zhiyu Han1, Zhenkuo Wu1, Yongcheng Huang2, Yongsheng Shi3, Wei Liu3 |
1Tongji University
2Xi’an Jiaotong University
3Smapow Engine Company |
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| ABSTRACT |
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A study on the design and combustion performance of a new spark-ignition compressed natural gas (CNG)
engine for light-duty automotive applications was carried out. The effects of natural gas fuel characteristics on engine design
were analyzed in guiding the design of the engine. One-dimensional simulations with added natural gas laminar flame speed
data were conducted in upfront to optimize the engine performance with the evaluation of the effects of compression ratio
(CR), intake variable valve timing (VVT), and spark timing, etc. The results were validated through engine dyno experiments.
It showed the CNG engine’s torque and BSFC could be increased by from 5.2 to 6.6 %, and from 4.6 to 5.7 % , respectively,
with increasing the CR from 10.5 to 12. At full engine loads, the intake VVT angles needed re-adjustments for improving the
torque output, while the original gasoline-engine adapted VVT resulted in the optimal BSFC under other operation conditions.
In additional, the transient emission characteristics of a passenger car powered by the CNG engine were also presented. The
CO2 emission of the vehicle under NEDC is 117.32 g/km, which meets China’s 2020 CO2 limit. When equipped with a
three-way catalyst, the vehicle can meet the China 6b emission standard. |
| Key Words:
CNG engine, Combustion, Engine simulation, Vehicular emission characterist |
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Corresponding Author.
Zhenkuo Wu , Email. 
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