Combustion Characteristics of HCCI in Motorcycle Engine

Mir

2018

Energies

Self Cite

The efficiency of an internal combustion engine (ICE) is essential for automobiles and motorcycles. Several studies have demonstrated that the homogeneous charge compression ignition (HCCI) is a promising technology for realizing engines with high efficiency and low emissions. This study investigated the combustion characteristics of the HCCI using a 125 cc motorcycle engine with n-heptane fuel. The engine performance, combustion characteristics, and thermal efficiency were analyzed from experimental data. The results revealed that a leaner air–fuel mixture led to higher engine efficiency and output. The improvement of engine output is contradictory to the general trend. Energy balance analysis revealed that lower heat loss, due to the low cylinder gas temperature of lean combustion, contributed to higher efficiency. A double-Wiebe function provided excellent simulation of the mass fraction burned (MFB) of the HCCI. Air cycle simulation with the MFB, provided by the double-Wiebe function, was executed to investigate this phenomenon. The results indicated that a better combustion pattern led to higher thermal efficiency, and thus the engine output and thermal efficiency do not require a fast combustion rate in an HCCI engine. A better combustion pattern can be achieved by adjusting air–fuel ratio (AFR) and the rates of dual fuel and exhaust gas recirculation (EGR).

Section: Methodsmentioning

confidence: 99%

Improving the Thermal Efficiency of the Homogeneous Charge Compression Ignition Engine by Using Various Combustion Patterns

Mir

2018

Energies

Self Cite

“…After these thermistors are connected with the input interface, Motohawk ECU for thermistor, voltage signals can be generated and read for engine control algorithm. In this study, cylinder head and oil temperature are kept above 120°C and 65°C respectively for stable HCCI operation (Wu et al, 2010).…”

Section: Methodsmentioning

confidence: 99%

“…A previous study has shown that HC and CO emissions, and coefficient of cycle variation (COV) of indicated mean effective pressure (IMEP) could be decreased during closed valve injection (Wu et al, 2010). Therefore, the fuel injection timing of 90 o bTDC (before top dead center) of compression stroke was chosen for experiments not only to avoid the liquid fuel from entering the cylinder directly but also to maintain the homogeneity of the air-fuel mixture.…”

Section: Methodsmentioning

confidence: 99%

Application of HCCI Engine in Motorcycle for Emission Reduction and Energy Saving

Chen

2015

Aerosol Air Qual. Res.

Self Cite

The exhaust emission of motorcycle engine is a big problem in Asia countries due to the large number of motorcycles. This study developed a homogeneous charge compression ignition (HCCI) engine for motorcycle application with highoperating efficiency and low exhaust emissions. The development was carried out on a 150 cc spark-ignition (SI) engine with an increased compression ratio to enhance compression temperature. Dimethyl ether (DME) was selected as the main fuel for HCCI operation due to the low self-ignition temperature. Gasoline was used as an additional fuel to adjust the ignitibility of the dual fuel mixture. The dual fuel and exhaust gas recirculation (EGR) were incorporated to expand the engine operating range. Experiments of varying DME flow rates, EGR ratios, and gasoline flow rates were performed to observe HCCI operating characteristics and to identify methods for controlling HCCI combustion. And then, the engine could be operated at speeds ranging from 2000 to 4000 rpm and BMEP (Brake Mean Effective Pressure) ranging from 1.56 to 4.86 bar. These operating points were found to have lower brake specific fuel consumption and lower CO and NO emissions as compared with the original SI engine. A range-extended electric motorcycle (REEM) was built from a conventional motorcycle by using the proposed HCCI engine as a range extender. The HCCI engine was operated at 3500 rpm with very stable and high efficiency to match the REEM. The fuel economy of the proposed motorcycle is 75.62 km L -1 , a 132% improvement compared with the original motorcycle. The control of switch from SI to HCCI will be the future work.

“…After these thermistors were connected to the input interface, Motohawk ECU for thermistor, voltage signals could be generated and read for engine-control algorithms. In this study, cylinder head and oil temperatures were held above 120°C and 65°C, respectively, for stable HCCI operation (Wu et al, 2010). …”

Section: Methodsmentioning

confidence: 99%

“…A fuel injection timing of 90° bTDC (before top dead center) of the compression stroke was chosen not only to prevent the liquid fuel from entering the cylinder directly but also to maintain the homogeneity of the air-fuel mixture (Wu et al, 2010).…”

Section: Testingmentioning

confidence: 99%

Experimental Study on HCCI Combustion in a Small Engine with Various Fuels and EGR

Chen

2016

Aerosol Air Qual. Res.

Self Cite

Because Asian countries have a large number of motorcycles, motorcycle engine exhaust emission poses a major problem in the region. Homogeneous charge compression ignition (HCCI) is a promising combustion technology with high efficiency and low nitrogen oxide emission. This study investigated the combustion characteristics of HCCI in a 150 cc motorcycle engine with three types of dual fuel. The main fuels consisted of dimethyl ether (DME), kerosene, and nheptane, and gasoline was the additive fuel. External exhaust gas recirculation (EGR) was used to expand the operating range of the engine. All test points were executed under stable HCCI operation with a coefficient of variation < 5%. A total of 107 data sets were obtained by adjusting the amount of main fuel, additive fuel, and EGR. Two-stage ignition was observed because of the diesel-like main fuels. The results revealed that the temperature at the start of combustion was approximately 500-700 K, and the temperature of the first-stage maximum heat release rate (MHRR1) was approximately 600-800 K. The relationship between the crank angle (CA) at which the mass fraction burnt is 50% (CA50) and the CAs of the maximum cylinder pressure, maximum cylinder gas temperature, and MHRR were linear. The R square for the curve fitting of each relationship was > 0.9. The findings suggest that adjusting the CA50 to a value greater than 5° after top dead center, or limiting the maximum cylinder pressure to < 50 bar is crucial to preventing excessive pressure rising. Overall, kerosene was deemed unsuitable for engines because of its high sulfur content, whereas DME is considered an excellent option.