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Characteristics and Performance Analysis of Intake Manifold in IC Engine of Asia Region
Haeng Muk Cho 동중앙아시아경상학회 2012 한몽경상학회 학술대회 Vol.2012 No.1
A diesel engine requires close tolerances to achieve its compression ratio. The air entering the engine must be clean, free of debris and as cool as possible. Also to improve engine’s efficiency, the compressed air must be cooled after being compressed. Development of Variable Counter-current Distribution Control (VCDC) technology ensures proper air intake and exhaust system. In this regard, design of valve controller and most importantly valve mixer mechanism with fin arrangements has taken into consideration. The term counter-current indicates the valve controller attachments and valve mixer position layout. Valve controller controls the intake airflow at a significant level and the valve mixture distributes the air to a form of streamline through the fin arrangements. There is no possibility of vortex generation which is important for smooth and linear flow of air inside the engine cylinder. A swirl combustion inside the combustion chamber take place that results uniform combustion, increase the flame propagation speed, overcoming the differences of turbulent flow, reduce the flame to burn, improves the function of the flame diffusion and serves to reduce the airflow noise. Pressure distribution ensures greater combustion pressure that results higher compression ratio as the air is compressed first and then the fuel injected which allow the IC diesel engine to be efficient.
Combustion and Emission Characteristics of a Natural Gas Engine under Different Operating Conditions
Haeng Muk Cho,Bang Quan He 대한환경공학회 2009 Environmental Engineering Research Vol.14 No.2
Natural gas is a promising alternative fuel of internal combustion engines. In this paper, the combustion and emission characteristics were investigated on a natural gas engine at two different fuel injection timings during the intake stroke. The results show that fuel injection timing affects combustion processes. The optimum spark timing (MBT) achieving the maximum indicated mean effective pressure (IMEP) is related to fuel injection timing and air fuel ratio. At MBT spark timing, late fuel injection timing delays ignition timing and prolongs combustion duration in most cases. But fuel injection timing has little effect on IMEP at fixed lambdas. The coefficient of variation (COV) of IMEP is dependent on air fuel ratio, throttle positions and fuel injection timings at MBT spark timing. The COV of IMEP increases with lambda in most cases. Late fuel injection timings can reduce the COV of IMEP at part loads. Moreover, engine-out CO and total hydrocarbon (THC) emissions can be reduced at late fuel injection timing.
A Study on Spark Ignition Natural Gas Engines
Cho Haeng-Muk The Korean Society of Marine Engineering 2006 한국마린엔지니어링학회지 Vol.30 No.4
Natural gas is a promising alternative fuel to meet strict engine emission regulations in many countries. Natural gas engines can operate at lean burn and stoichiometric burn conditions with different combustion and emission characteristics. In this paper, the fuel economy, emissions, misfire, knock and cycle-to-cycle variations in indicated mean effective pressure of lean burn natural gas engines are highlighted. Stoichiometric burn natural gas engines are briefly reviewed. To keep the output power and torque of natural gas engines comparable to that of gasoline engines, high boosting pressure should be used. High activity catalyst for methane oxidation and lean deNOx system or three way catalyst with precisely control strategies should be developed to meet stringent emission standards.
Methodology for Describing Different Phase States of Molecular Nitrogen
Cho, Haeng Muk,Kudryavtsev, I.N.,Kramskoy, A.V. The Korean Society for Energy 2014 에너지공학 Vol.23 No.4
A theory-based methodology for describing the thermodynamic properties of molecular nitrogen is presented. The results obtained indicate a successful application of a fully consistent statistical method for the description of a molecular system in different phase states. The method employs a density of states equation for solid nitrogen and a perturbation potential for gaseous and liquid nitrogen. The main characteristics of the calculation method include the need for a minimal number of initial data and the absence of fitting parameters. The adequacy of the physical model that is the basis for the method allows a description of existing experimental data and the peculiarities of the thermodynamic properties.
Control of Water Heat Recovery Chiller Using Split Condenser Templifier Application
Cho, Haeng-Muk,Mahmud, Iqbal The Korean Society for Energy 2009 에너지공학 Vol.18 No.1
By using the heat recovery of water-cooled chillers, it is possible to reduce the energy operating costs positively and at the same time it could fulfill the heating re-heat air conditioning system as well as the hot water requirements. Basically templifiers are designed to economically to turn the waste heat into useful heat. Waste heat is extracted from a fluid stream by cooling it in the evaporator, the compressor amplifies the temperature of the heat and the condenser delivers the heat to heating loads such as space heating, kitchens and domestic hot water. Design of higher water temperature requirements and split condenser heat recovery chiller system (using of templifiers) produced hotter condenser water approximately up to $60^{\circ}C$ and control the entire heat recovery system.
Cho Haeng-Muk The Korean Society of Marine Engineering 2005 한국마린엔지니어링학회지 Vol.29 No.7
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.