• Journal of Advanced Marine Engineering and Technology
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• v.29 no.7
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• pp.722-728
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• 2005

In this paper, the effects of ethanol blended gasoline on emissions and their catalytic conversion efficiency characteristics were investigated in a multiple-point EFI gasoline engine, The results show that with the increase of ethanol concentration in the blended fuels, THC emissions were drastically reduced by up to thirty percent, And brake specific fuel consumption was increased, but brake specific energy consumption could be improved. However, unburned ethanol and acetaldehyde emissions increased. Pt/Rh based three-way catalysts were effective to reduce acetaldehyde emissions, but had low catalytic conversion efficiency for unburned ethanol. The effect of ethanol on CO and NOx emissions and their catalytic conversion efficiency had close relation to the engine's speed, load and air/fuel ratio. Furthermore fuels blended with thirty percent ethanol by volume could dramatically reduced THC CO and NOx emissions at idle speed.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.5
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• pp.9-16
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• 2007

Since the liquid phase LPG injection(LPLI) system has an advantage of higher power and lower emission characteristics than the mixer type fuel supply system, many studies and applications have been conducted. However, the heat extraction, due to the evaporation of liquid fuel, causes not only a dropping of LPG fuel but also icing phenomenon that is a frost of moisture in the air around the nozzle tip. Because both lead to a difficulty in the control of accurate air fuel ratio, it can result in poor engine performance and a large amount of HC emissions. The experimental investigation was carried out on the bench test rig in this study. It was found that n-butane, that has a relatively high boiling point($-0.5^{\circ}C$), was a main species of droplet composition and also found that the droplet problem was improved by the use of a large inner to outer bore ratio nozzle whose surface roughness is smooth. The icing phenomena were decreased when the an engine head temperature was increased, although a large amount of icing deposit was still observed in the case of $87^{\circ}C$. Also, it was observed that the icing phenomenon is improved by using anti-icing bushing.

• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.1-10
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• 2023

Due to the development of the industrial revolution, regulations on exhaust emissions have been continuously strengthened to reduce the rapidly increasing greenhouse gas emissions. The use of environmentally friendly fuels is essential to meet these regulations. Hydrogen has been attracting attention as a future environmentally friendly fuel, but due to its material properties, it faces significant challenges in handling and storage. As an alternative, ammonia has been proposed. Ammonia can be easily liquefied at room temperature compared to hydrogen and has a high energy density. In order to examine the applicability of ammonia as an engine fuel, experiments were conducted to investigate the effects of changes in combustion control parameters in a direct injection ammonia combustion engine. The experiments were conducted by varying two variables: spark timing and excessive air ratio. Observations were made on combustion stability and the trends of exhaust emissions such as nitrogen oxides and unburned ammonia under the conditions of an engine speed of 1,500 rpm and medium to high loads (brake torque of 200 Nm). By optimizing the combustion control parameters, conditions for stable combustion even when using ammonia as the sole fuel were identified, and plans are underway to apply strategies for future expansion of the operating range.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.8
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• pp.1164-1171
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• 2002

This study analyzed the dependence of part load performance of simple cycle gas turbines on their design performance. Various parametric calculations were carried out to examine effects of design temperature ratio, pressure ratio and component efficiencies using a simplified analysis. In addition, a more practical analysis was done for realistic design conditions with the aid of a comprehensive performance analysis program. The results show that gas turbines with higher design performance exhibit less efficiency degradation during part load operation. The influence of power control method (fuel only centre) and air flow control) on part load performance was examined as well.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.2
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• pp.203-210
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• 2015

This paper investigates the failure of a car with a 2.5-liter CRDi engine of the Hyundai Company. The failure is caused by intermittent poor acceleration while driving. To analyze the cause, we investigated the air intake volume, the fuel injection, and the air-fuel ratio, which were determined to be normal. The brake switch signal error was discovered while analyzing the function that limits the output of the engine. While investigating the cause, we discovered the corrosion of the pins on the connector of the brake switch. We determined that it was generated by soapy water flowing in the solar film. Therefore, the cause of the failure was the brake switch signal errors. Additionally, we determined that ECM was the normal fail-safe mode that implemented the override device for safety during normal acceleration. Based on these results, further solar film experiments must be conducted to fully elucidate the causes.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.5
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• pp.9-16
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• 2022

Syngas, also known as synthesis gas, synthetic gas, or producer gas, is a combustible gas mixture generated when organic material (biomass) is heated in a gasifier with a limited airflow at a high temperature and elevated pressure. The present research was aimed at modifying the existing LPG engine generator for fully operated syngas. During this study, the designed gasifier-powered woodchip biomass was used for syngas production to generate power. A 6.0 kW LPG engine generator was modified and tested for operation on syngas. In the experiments, syngas and LPG fuels were tested as test fuels. For syngas production, 3 kg of dry woodchips were fed and burnt into the designed downdraft gasifier. The gasifier was connected to a blower coupled with a slider to help the air supply and control the ignition. The convection cooling system was connected to the syngas flow pipe for cooling the hot produce gas and filtering the impurities. For engine modification, a customized T-shaped flexible air/fuel mixture control device was designed for adjusting the correct stoichiometric air-fuel ratio ranging between 1:1.1 and 1.3 to match the combustion needs of the engine. The composition of produced syngas was analyzed using a gas analyzer and its composition was; 13~15 %, 10.2~13 %, 4.1~4.5 %, and 11.9~14.6 % for CO, H₂, CH₄, and CO₂ respectively with a heating value range of 4.12~5.01 MJ/Nm³. The maximum peak power output generated from syngas and LPG was recorded using a clamp-on power meter and found to be 3,689 watts and 5,001 watts, respectively. The results found from the experiment show that the LPG engine generator operated on syngas can be adopted with a de-ration rate of 73.78 % compared to its regular operating fuel.

• Journal of the Korean Institute of Gas
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• v.24 no.6
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• pp.28-33
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• 2020

In this study the possibility of hydrogen as a fuel in a small-sized two-stroke SI (Spark ignition) engine was investigated. For this purpose, experimental setup including an engine, a dynamometer, equipments for hydrogen and lubricant oil supply was prepared. And then preliminary experiments for the hydrogen-fueled engine combustion were conducted. In the case of hydrogen-fueled engines comparing to gasoline backfire occurs when the excess air ratio is lower than a specific value. This can cause engine power reduction and damage to the engine parts. The engine was controlled to operate at lean conditions to prevent backfire. Through the control of excess air ratio, the maximum engine brake power output of 3 kW was achieved in a 210 cc engine, while it was 6 kW in case of gasoline fuel.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3311-3316
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• 2007

To analyze the influence of valve overlap period on a backfire occurrence, the single cylinder research engine with MCVVT(Mechanical Continuous Variable Valve Timing) system is developed and backfire limit equivalence ratio defined as fuel-air ratio equivalence ratio at which backfire occurs is examined according to various valve overlap period. The MCVVT is the system to control valve overlap period by mechanical device. It is estimated that the lower valve overlap period has the higher backfire limit equivalence ratio though the same energy is supplied. When the valve overlap period is changed from 30$^{circ}$ CA to 0$^{circ}$ CA, backfire limit equivalence ratio is increased 74%, approximately. It means that valve overlap period is concern in backfire occurrence, and may be one of the methods for controlling back fire occurred in a $H_2$ engine.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.4
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• pp.561-569
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• 2002

This paper presents an investigation on $C_2$, CH, OH radicals and NOx emissions in partially premixed flames with acoustic excitation. The radicals are visualized by the digital image technique with optical filters and ICCD camera while NOx emissions are determined by a chemiluminescent detection(NOx analyser). The measurements are made in flames with an overall equivalence ratio (${\phi}_o$) 0.5 and a center tube equivalence ratio(${\phi}_c$) varing from 1.1 to 5.0 for a constant fuel flow rate. In the case of excitation, the visual shape of the flame is changed from laminar to turbulent-like flames. Images of $C_2$, CH, and OH radicals resemble those of the flame appearances as the excitation phase is varied, and the radicals generated at the upstream are convected toward the downstream. It is inferred that the flame characteristics is affected by the flow characteristics of air-fuel mixture. In the case of acoustic excitation, OH radicals are much increased relative to unexcitation. From the radicals and flame visualization under acoustic excitation, the reduction of flame length affects the shorter residence time of center tube mixture, and significantly influences the NOx reduction.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.2
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• pp.83-90
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• 2014

The main purpose of the study is to investigate the ideal manner and ratio to inject gasoline and DME simultaneously into intake port, and moreover to confirm the characteristics of combustion and emission of engine. Experimental conditions are 1200 rpm, compression ratio 8.5, intake air temperature (383 K). Internal cylinder pressure was collected to confirm the characteristics of combustion in order to calculate the heat release rate in the cylinder. In addition, HORIBA (MEXA 7100) which was possible analyzing emissions (NOx, CO, HC) was used. Vanguard gasoline engine (23HP386447) was used in this experiment. The result show that fuel design (DME-Gasoline) leads to the decrease of low temperature heat release, which is a benefit for higher-load on the HCCI engine. Also, IMEP and the indicated thermal efficiency increase with combustion-phasing retard, and these observations can be explained by considering the control of low temperature oxidation of DME.