• Journal of the Korean Society of Combustion
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• v.19 no.1
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• pp.17-28
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• 2014

In this study, the laminar burning velocity of syngas fuel($H_2/CO$) and flame structure with various hydrogen contents were studied using both experimental measurements and detailed kinetic analysis. The laminar burning velocities were measured by the angle method of Bunsen flame configuration and the numerical calculations including chemical kinetic analysis were made using CHEMKIN Package with USC-Mech II. A wide range of syngas mixture compositions such as $H_2$ : CO = 10 : 90, 25 : 75, 50 : 50, 75:25 and equivalence ratios from lean condition of 0.5 to rich condition of 5.0 have been considered. The experimental results of burning velocity were in good agreement with previous other research data and numerical simulation. Also, it was shown that the experimental measurements of laminar burning velocity linearly increased with the increment of $H_2$ content although the burning velocity of hydrogen is faster than the carbon monoxide above 10 times. This phenomenon is attributed to the rapid production of hydrogen related radicals such as H radical at the early stage of combustion, which is confirmed the linear increase of radical concentrations on kinetic analysis. Particular concerns in this study are the characteristics of burning velocity and flame structure different from lean condition for rich condition. The decrease of OH radicals and double peaks are observed with $H_2$ content in rich condition once $H_2$ fraction exceeds over threshold.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.41-46
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• 2018

In this research, numerical analysis was performed to determine the effects of hydrogen on biogas combustion for homogeneous charged compression ignition (HCCI) engines. The target engine specifications were a 2300cc displacement volume, 13:1 compression ratio, 15kW of electricity, and 1.2 bar boost pressure. The engine speed was fixed to 1800rpm. By varying the excess air ratio and hydrogen contents, the cylinder pressure, nitric oxide, and carbon dioxide were measured as a function of the hydrogen contents. According to preliminary studies related to the reaction mechanism for methane combustion and oxidation, a GRI 3.0 mechanism as the base mechanism was selected for HCCI combustion calculations describing the detailed reaction mechanism. By adding hydrogen, NO was increased while $CO_2$ was decreased. The cylinder pressure was also increased, having advanced timing for the maximum cylinder pressure and pressure rise region. Furthermore, lean operation limits were extended by adding hydrogen to the HCCI engine.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.4
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• pp.41-47
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• 2020

This study aims to develop eco-friendly propellant that reduce the generation of harmful gases such as HCl gas and increase the emmision of nitrogen gas emissions. For this purpose, GUDN(N-Guanylurea dinitramide) and BTATz(3,6-bis(1H-1,2,3,4-tetrazol-5-ylamino)-1,2,4,5-tetrazine), which are low carbon high nitrogen materials, were used instead of AP(Ammonium Perchlorate) and Al(Aluminium), which are gernerally used in solid propellant. The prepared propellants were analyzed for mechanical properties and combustion characteristics, performance and AGARD smoke classification. Compared with AP/Al propellant, GUDN/BTATz propellant tended to decrease mechanical and combustion rate. Also, as a result of the static test after the production of the 4-inch motor, the performance of combustion of the GUDN/BTATz propellant decreased, but it was confirmed that the secondary smoke was improved by reducing harmful gases such as HCl gas.

• Journal of the Korean Wood Science and Technology
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• v.51 no.3
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• pp.207-221
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• 2023

The increasing demand for clean energy requires considerable effort to find alternative energy sources, such as briquettes. This research aims to develop a charcoal briquette with added pine resin (API) that has excellent combustion speed and distinctive aroma. Briquettes are composed of charcoal, pine resin (concentration: 0%-30%), and starch (up to 7%). They are produced in several stages, including coconut shell pyrolysis in conventional combustion, to obtain charcoal for the briquette precursor. Briquette compaction is conducted by mixing and densifying the charcoal, pine resin, and starch using a hydraulic press for 3 min. The hydraulic press has a total surface area and diameter of 57.7 cm² and 3.5 cm, respectively. The briquettes are dried at different temperatures, reaching 70℃ for 24 h. The study results show that the briquettes have a thickness and diameter of up to 2 and 3.5 cm, respectively; moisture of 2.18%-2.62%; ash of 11.61%-13.98%; volatile matter of 27.15%-51.74%; and fixed carbon content of 40.24%-59.46%. The compressive strength of the briquettes is 186-540 kg/cm². Their calorific value is 5,338-6,120 kcal/kg, combusting at a high speed of 0.15-0.40 s. The methoxy naphthalene, phenol, benzopyrrole, and lauryl alcohol; ocimene, valencene, and cembrene are found in the API. The API briquette has several chemical compounds, such as musk ambrette, ocimene, sabinene, limonene, 1-(p-cumenyl) adamantane, butane, and propanal, which improve aroma, drug application, and fuel production. Accordingly, API briquettes have considerable potential as an alternative energy source and a health improvement product.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.253-254
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• 2014

지구온난화 문제는 한국가의 문제가 아니라 인류의 문제로 대두되어 많은 이에대한 많은 연구가 이루어 지고 있다. 지구온난화의 주 대상물질인 화석연료로부터 연소시 발생하는 이산화탄소를 감축하기위한 많은 규제와 노력이 요구된다. CCS(Carbon Capture & Storage)란 화석연료로 부터 연소시 대기 중으로 배출되는 온실가스($CO_2$)를 포집하여 재생 또는 지중, 해양에 저장하는 기술로서 국가녹색성장 핵심기술중의 하나로 분류되며, $CO_2$ 회수방안, 저장, 처리관련 연구를 비롯하여 국내외 적으로 활발한 연구가 이루어 지고 있다. 또한 순산소 연소기술을 통한 $CO_2$ 회수, 처리기술은 연료의 산화제를 공기대신 순도 95% 이상의 고농도 산소를 이용하여 순산소연소를 하며, 이때 발생하는 배가스의 대부분은 $CO_2$와 수증기로 구성되어 있다. 발생된 배가스의 약 70~80%를 다시 연소실로 재순환시켜 연소기의 열적 특성에 적절한 연소가 가능하도록 최적화함과 동시에 배가스의 $CO_2$ 농도를 80% 이상으로 농축시켜 회수를 용이하게 하며, 동시에 공해물질은 NOx 발생량을 10ppM 이하로 줄일 수 있는 기술이다. 천연가스를 생산하는 LNG기지에서 연소에 의한 이산화탄소를 발생시키는 기기로는 수중연소식기화기(SMV ; Submerged Combustion Vaporizer)를 들 수 있다. SMV는 버너를 이용하여 $-162^{\circ}C$ LNG를 $10^{\circ}C$의 LN로 기화시키는 설비로서 특히 동절기에 작동시키며 $CO_2$를 배출시키는 연소기다. 본 연구에서는 수중연소식 SMV에 순산소 연소방식을 적용하여 천연가스와 산소를 연소시키므로서 발생되는 $CO_2$를 LNG냉열을 이용 액체화 시켜 회수하는 연구를 수행하고 있다. 내용중에 수중연 소식 SMV에 대한 순산소 연소기를 개발하는 연구를 수행하였으며, 실제 SMV의 1/10크기, 열량기준 1/900로 모형을 제작하여 실험하였다. 연소기 노즐 은 직경 0.6mm, 배가스가 수조내에서 48개의 노즐을 제작하였다. 실험결과 일정량 이상의 $CO_2$ EGR율이 일정 값 이상이 되면 화염의 길이가 공기/NG 화염 길이와 큰 차이가 없었으며 $CO_2$ EGR율이 100%이상에서는 $CO_2$ EGR율 증가에 따른 화염길이 변화는 크게 나타나지 않았다. CO 배출 농도는 공기/NG 연소의 경우보다 높게 나타났으며, ${\lambda}$가 1.4보다 높은 조건에서는 측정되지 않았다. NOx의 배출 농도는 약 1~8ppm으로 나타났다.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.5
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• pp.75-82
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• 2010

To study the combustion characteristics of forest fuel by fire intensity, the experiment of combustion characteristics on Pinus Densiflora living leaves, which is the weakest species to the forest fire, was delivered, using variables of heat flux(25 kW/$m^2$, 50 kW/$m^2$, 75 kW/$m^2$). With the equipment of Cone calorimeter, the characteristics of ignition, heat, smoke release, CO and $CO_2$ release, and mass loss were analyzed. Pinus Densiflora living leaves containing moisture of 60.66% were not ignited at the heat flux of variables 25 kW/$m^2$, 50 kW/$m^2$, 75 kW/$m^2$. In proportion to the heat flux value, heat release amount and heat release rate reached maximum value rapidly: higher variables came to the maximum by the half rapidity and the maximum value were twice higher than the former lower variables respectively. As for the smoke release, the less heat flux the variable had, the more smoke release it had, due to incomplete combustion. The release amount of CO and $CO_2$ had more maximum value as the heat flux increased and more radiant heat meaned more carbon oxide. When the forest fire breaks out, therefore, a great amount of CO and $CO_2$ will be released by Pinus Densiflora.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.911-917
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• 2015

The objective of this work focuses on the analysis of injection rate and macroscopic spray behavior characteristics with injection pressures as well as combustion and exhaust emission characteristics with injection timing and injection pressure by using a common rail single-cylinder diesel engine. The injection rate was measured by applying the Bosch method, and macroscopic spray behavior characteristics were analyzed with a constant-volume vessel and a high-speed camera. In addition, combustion and emission characteristics were analyzed in a common-rail single-cylinder diesel engine with precise control of fuel injection timing and pressure. For injection pressures of 30MPa and 50MPa, the injection rate was higher at 50 MPa, and the spray development (penetration) was also higher in the same elapsed time. The peak in-cylinder pressure and rate of heat release showed a tendency to decline as injection timing was delayed, and the peak in-cylinder pressure and rate of heat release were slightly higher for higher injection pressures. Higher injection pressures also reduced the mean effective pressure, while the indicated mean effective pressure and torque increased as injection timing was delayed to TDC. Nitrogen oxides had a peak level at injection timings of $BTDC20^{\circ}$(30MPa) and $BTDC15^{\circ}$(50MPa); carbon monoxide emissions were reduced by delaying injection timing from $BTDC30^{\circ}$.

• Korean Journal of Materials Research
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• v.9 no.8
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• pp.817-824
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• 1999

The $Al_2$$O_3$-SiC composite powder was prepared by Self-propagating High-Temperature Synthesis(SHS) process using $SiO_2$Al and C powders as raw material. The effects of the molar ratio in raw material, compaction pressure, initial temperature of reactants on the products and combustion process were studied. Self-propagating high temperature synthesis of $SiO_2$/Al/C system should be preheated above $400^{\circ}C$ owing to the low combustion temperature. As the result of the combustion reaction, the purity of final product became better than that of reactants. In this system, the optimum molar ratio of $SiO_2$:Al:C was 3.0:4.0:6.0. The free carbon was removed by roasting at $650^{\circ}C$ for 30min. In this study, pressureless sintering was very dffective both for controlling the disintegration of specimen with powder bed and for obtaining dense sintered-body at $1700^{\circ}C$. The sintered-body produced with hot-pressing was about 98% of the theoretical relative density.

• Fire Science and Engineering
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• v.31 no.2
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• pp.37-43
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• 2017

The combustion characteristics of four kinds of wood specimens, such as Japan cedar, spruce, lauan, and red pine, were tested using the standards of Cone calorimeter (ISO 5660-1, 2) and smoke density tester (ASTM E 662). Japan cedar caught fire the quickest but the mean heat release rate was the lowest, $58.52kW/m^2$. The mean heat release rate of red pine appeared to be the highest, $71.75kW/m^2$. The lauan and Japan cedar generated relatively large amounts of carbon monoxide while the red pine and the spruce generated relatively large amounts of carbon dioxide. The red pine generated large amounts of smoke and the spruce generated the least amounts of smoke than the other samples. The total smoke release rate in the dynamic method was the highest in red pine and the lowest in spruce. The smoke density of red pine in the static method was highest in the non-flaming and flaming methods. In the non-flaming method, the smoke density of lauan was the second highest, whereas the flaming method was the least. In terms of the heat release rate, the fire risk from red pine was highest among the four test specimens. From the viewpoint of smoke generation, red pine was the most dangerous material in both dynamic and static methods.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.4
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• pp.429-439
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• 1996

A comprehensive air quality monitoring was carried out in this study to investigate the concentrations of criteria air pollutants in indoor and outdoor air of public facilities in Taegu area. Four different kinds of public facilities were seleced as sampling sites, which are underground stores, stations & terminals, general hospitals, and department stores. Each group of the public facilities was consisted of three different sampling sites. As a consequence, a total of 12 different sampling sites were surveyed throughout this study. Sampling was conducted simultaneously indoors, three times per day (in the morning, afternoon, and evening) and four times per year (spring, summer, fall, and winter) at each sampling site during the period of October 1994 to July 1995. A range of criteria pollutants were measured in order to obtain a broad profile of indoor and ambient air quality, including total suspended particles (TSP), carbon monoxide (CO), carbon dioxide ($CO_2$), formaldehyde (HCHO), sulfur dioxide ($SO_2$), and nitrogen dioxide ($NO_2$). In addition, temperature, relative humidity, and air current were measured on site together with those air pollutants. Results of this study indicated that the indoor levels of TSP, CO, $SO_2, and NO_2$ appeared to be generally higher in stations/terminals and underground stores than those in department stores and hospitals. However, HCHO and $CO_2$ were found to have higher levels in the department stores and hospitals than other places, indicating that the effects of indoor sources for these pollutants are significantly different from other combustion related pollutants such as TSP, CO, and $SO_2$. It was also found that there are marked seasonal and daily variations both in indoor and outdoor air quality. In general, combustion related pollutants such as CO, $SO_2$ and $NO_2$ showed a typical pattern of higher levels in winter than insummer, and also higher in the morning and/or in the evening than in the afternoon. However, the seasonal and daily patterns of HCHO appeared to be opposite to the combustion related pollutants, i.e., higher both in summer and in the afternoon, implying the effect of temperature on the volatilization from indoor sources of HCHO. Results of correlation analyses between indoor and outdoor air quality also indicated that the effects of outdoor sources on the indoor levels of TSP, $SO_2$, CO, and $NO_2$ and much significant, whilst no significant correlations between indoor and outdoor levels were found for HCHO and $CO_2$.