Market of products equipped with small engines is increasing every year all over the world. Small engine imply that it is 4-stroke and 2-stroke cycle engine less than rated power 19kW. Especially, because 2-stroke cycle engine has characteristics that its structure is simple and is inexpensive compa...
Market of products equipped with small engines is increasing every year all over the world. Small engine imply that it is 4-stroke and 2-stroke cycle engine less than rated power 19kW. Especially, because 2-stroke cycle engine has characteristics that its structure is simple and is inexpensive compared to 4-stroke cycle engine, it is generally used for small engines. In the country, there are not many researches about 2-stroke engine. Also, studies about Class Ⅳ(20 ~ 50cc, handheld) 2-stroke engine is very few. Its technology leaves in level of agriculture and gardening products while application field and demand market of class Ⅳsmall engine is spreading widely. The inherent drawbacks of two-stroke engines are the high HC emission level and poor fuel economy. These problems are directly related to short-circuit loss of charge during the scavenging process. To improve performance and reduce exhaust emissions of small 2-stroke engines, stratified scavenging, manifold and in-cylinder injection have been studied by many researchers. Additionally, by adopting the alternative fuels, studies to reduce hydrocarbon emissions have been carried out. The engine used in this study was a single cylinder, two-stroke, air-cooled 23cc engine for LPG trimmer. In this study, performance and emissions characteristics with commercial LPG and gasoline engine were examined and compared under variables as throat open ratio and load. Also. performance and emissions characteristics with supplying methods of lubricating oil were analyzed. The engine speed, torque, fuel consumption time and HC, CO, NOX, O₂ emissions were measured. The conclusions of this study are summarized below: 1) In the experiment according to throat open ratio, net heat efficiency of gasoline engine was higher than LPG engine near 0.2 of open ratio only and LPG engine emitted more HC emissions than LPG engine except for 0.31 of open ratio. In both gasoline engine and LPG engine, NO_(X) emissions was less than 700ppm. 2) In the experiment according to increase of dynamometer load at WOT, power of gasoline engine was 230W higher than LPG engine and net heat efficiency was similar below 8,000rpm. Gasoline engine emitted 45,000ppm of HC emissions near 10,000rpm and LPG engine emitted more than 100,000ppm above 8,400rpm. CO emissions of gasoline engine was high in ppm of 18,000 at 10,000rpm and that of LPG engine was about 18,000ppm above 8,000rpm. 3) In the experiment according to oil supplying methods, oil pumping method consumed more oil by 0.002ml/s compared to oil mixing method and difference of fuel consumption per revolution was little. Lubricating oil doesn't have effect on concentration of HC emissions. Regardless of oil supplying methods, CO emissions was similar.
Market of products equipped with small engines is increasing every year all over the world. Small engine imply that it is 4-stroke and 2-stroke cycle engine less than rated power 19kW. Especially, because 2-stroke cycle engine has characteristics that its structure is simple and is inexpensive compared to 4-stroke cycle engine, it is generally used for small engines. In the country, there are not many researches about 2-stroke engine. Also, studies about Class Ⅳ(20 ~ 50cc, handheld) 2-stroke engine is very few. Its technology leaves in level of agriculture and gardening products while application field and demand market of class Ⅳsmall engine is spreading widely. The inherent drawbacks of two-stroke engines are the high HC emission level and poor fuel economy. These problems are directly related to short-circuit loss of charge during the scavenging process. To improve performance and reduce exhaust emissions of small 2-stroke engines, stratified scavenging, manifold and in-cylinder injection have been studied by many researchers. Additionally, by adopting the alternative fuels, studies to reduce hydrocarbon emissions have been carried out. The engine used in this study was a single cylinder, two-stroke, air-cooled 23cc engine for LPG trimmer. In this study, performance and emissions characteristics with commercial LPG and gasoline engine were examined and compared under variables as throat open ratio and load. Also. performance and emissions characteristics with supplying methods of lubricating oil were analyzed. The engine speed, torque, fuel consumption time and HC, CO, NOX, O₂ emissions were measured. The conclusions of this study are summarized below: 1) In the experiment according to throat open ratio, net heat efficiency of gasoline engine was higher than LPG engine near 0.2 of open ratio only and LPG engine emitted more HC emissions than LPG engine except for 0.31 of open ratio. In both gasoline engine and LPG engine, NO_(X) emissions was less than 700ppm. 2) In the experiment according to increase of dynamometer load at WOT, power of gasoline engine was 230W higher than LPG engine and net heat efficiency was similar below 8,000rpm. Gasoline engine emitted 45,000ppm of HC emissions near 10,000rpm and LPG engine emitted more than 100,000ppm above 8,400rpm. CO emissions of gasoline engine was high in ppm of 18,000 at 10,000rpm and that of LPG engine was about 18,000ppm above 8,000rpm. 3) In the experiment according to oil supplying methods, oil pumping method consumed more oil by 0.002ml/s compared to oil mixing method and difference of fuel consumption per revolution was little. Lubricating oil doesn't have effect on concentration of HC emissions. Regardless of oil supplying methods, CO emissions was similar.
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