Methodology for Describing Different Phase States of Molecular Nitrogen

Haeng Muk Cho,I.N.Kudryavtsev,A.V.Kramskoy 한국에너지학회 2014 에너지공학 Vol.23 No.4

Control of Water Heat Recovery Chiller Using Split Condenser Templifier Application

Haeng Muk Cho 한국에너지학회 2009 에너지공학 Vol.18 No.1

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.

Benefit Analysis of CNG as an Automobile Fuel

Haeng Muk Cho(조행묵),Md. Iqbal Mahmud(Md. 이크발 마흐무드) 한국청정기술학회 2009 청정기술 Vol.15 No.1

전 세계적으로 급성장하고 있는 자동차연료로 압축천연가스(CNG)의 사용이 일반화되고 있다. 1996년도에 100만 대이던 CNG자동차가 2006년도에는 5배가 증가하였으며, 지금도 계속 증가하고 있는 추세이다. CNG연료는 가솔린 및 디젤연료에 비하여 효율적이고 완전연소에 가까워 청정연료로서 적합하다. 또한 배출 가스로서 일산화탄소, 탄화수소 및 질소산화물 등이 다른 연료에 비하여 유리하며, 경제적인 변에서도 투자가치가 있다. 본 연구에서는 천연가스자동차의 환경적인 특성과 효율적이고 경제적인 면에서 고찰하고자 한다. The adoption of compressed natural gas (CNG) as a vehicle fuel is a common phenomenon as it is accelerating worldwide. Increasing number of CNG driven vehicles around the world has jumped up from one million in 1996 to five million in 2006. CNG as a vehicle fuel is very popular to the end users because of its clean-burning properties and cost effective solution compared to other alternative fuels like diesel and gasoline. The use of CNG as a fuel reduces vehicular emission that is consisted of carbon monoxide (CO), hydrocarbons (HC), oxides of nitrogen (NO,), carbon dioxide (CO₂) etc. This research highlights the characteristics of CNG vehicles, CNG arrangement in the vehicles, CNG fueling procedures and most importantly the environmental and economic factors that are highly considered as cost effective solution for the flexibility of using CNG in the automobiles.

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.

The Effect of Fuel Injection Timing on the Combustion and Emission Characteristics of a Natural Gas Fueled Engine at Part Loads

Haeng-Muk Cho 한국마린엔지니어링학회 2008 한국마린엔지니어링학회지 Vol.32 No.7

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.

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.

정적연소실을 이용한 메탄올 혼합연료의 연소특성에 관한 연구

조행묵(Haeng Muk Cho),이창식(Chang Sik Lee) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

This work is to obtain the combustion characteristics of methanol-blended fuel in a constant volume combustion chamber. The combustion characteristics of methanol-blended fuel in a constant volume combustion chamber are investigated for various conditions of equivalence ratio, initial pressure, and pre-mixture temperature of mixture. The results of combustion experiment show that the combustion pressure is increased in accordance with the increase of initial pressure in the chamber. The combustion duration of blended fuel is increased with the decrease of air 뺈uel equivalence ratio of methanol-blended fuel.

한국의 잠재적인 연료인 CNG연료의 성능 및 배출물에 관한 연구

조행묵(Haeng Muk Cho),Bhupendra Singh Chauhan 한국가스학회 2009 한국가스학회지 Vol.13 No.6

가솔린 엔진은 전 세계적으로 중소형 및 대형차 등 전반적으로 사용되고 있으며, 장기적으로 차량 부하에 따른 배기가스의 증가가 주변 환경에 대한 위협이 가중되고 있어 여기에 대한 대처가 필요하다. CNG엔진은 기존의 가솔린 SI 엔진에 비하여 유해 배출가스 농도가 적어 다른 연료에 비해여 청정연료로서 유리하며, 많은 관련 연구자들이 여기에 대한 여러 논문을 통하여 잠재적 청정연료로서 확인되었다. 출력과 열효율의 측면에서 약간 가솔린 연료에 비하여 떨어지지만 일산화탄소와 탄화수소 배출량은 유리하며, 질소산화물은 약간 증가하는 현상이 나타났다. 본 논문에서는 기존 가솔린엔진과 CNG엔진의 배출물을 비교 검토하였다. Gasoline engine have proved its utility in light, medium and heavy duty vehicle in every sector of the world community. The concern about long term availability of petroleum and the increasing threat for the environment by the increasing load of vehicular emission, compel the technology to upgrade itself for meeting the challenges. CNG is environmentally clean alternative to the existing SI Engines with out much change in the hardware. Many researchers have found this as a potential substitute to meet the energy requirement. Higher octane number and higher self ignition temperature make it a good gaseous fuel. Although power output is slightly lesser than the gasoline it’s thermal efficiency is better than the gasoline for the same SI Engine. Results showed that reduced CO, hydrocarbon emissions is a favorable outcome, with slight increase in NOx emission when compared with gasoline fuel to dual fuel mode in the existing SI Engines.