• Journal of The Korean Society of Agricultural Engineers
• /
• v.53 no.6
• /
• pp.17-22
• /
• 2011

Biomass gasification provides synthesis gas or syngas that can be used for internal combustion engines as fuel or chemical synthesis as feedstock. Among different types of gasifiers, downdraft gasifier can produce relatively clean syngas with lower tar contents. In this study, a downdraft gasifier was fabricated with 150 mm of hearth diameter to gasify woodchip that is commercially available in this country. After drying woodchip to about 20 %, gasification experiments were conducted measuring temperature, pressure, air and gas flow rates. The volumetric concentrations of CO, $H_2$, $CO_2$, $CH_4$ were 10.7~14.5, 16.5~21.4, 12.5~16.6, and 2.3~2.9, respectively. They were overall within the ranges of the results that the previous studies showed. However, CO concentration was relatively lower and H2 was slightly higher than those from other studies. It seemed that water gas shift reaction was occurred due to the moisture in the fuel woodchip. Additional drying process coupled with syngas cooling would be required to improve the overall efficiency and syngas quality.

• Korean Chemical Engineering Research
• /
• v.45 no.5
• /
• pp.424-432
• /
• 2007

Biodiesel is gaining more attractive due to its eco-friendly and the fact that it is prepared from renewable sources. It is monoalkyl esters of long chain fatty acids derived from vegetable oils and animal fats via transesterification reaction with alcohol in the presence of catalyst. This paper will review briefly (1) the effect of reaction conditions such as catalyst type, amount of free fatty acid and moisture, molar ratio of alcohol and oil, alcohol type, reaction temperature and time and stirring intesity, (2) downstream process of biodiesel after transesterification reaction, and (3) potentialities of biodiesel as an alternative fuel based on its properties in diesel engines.

• Korean Journal of Materials Research
• /
• v.10 no.2
• /
• pp.166-170
• /
• 2000

Nuclear fuel $UO_{2+x}$ power was produced from concentrated $UF_6$ by the DCP(Dry Conversion Process). The characterstics of $UO_{2+x}$ powder, prepared with respect to steam flowing conditions and temperature variations in a rotary kiln reactor, have been investigated with a uranium analyzer, water vapor measurement, and SEM. Fluorine content of the powder could be reduced to 8ppm. The moisture content was found to be optimized.

• Journal of ILASS-Korea
• /
• v.16 no.3
• /
• pp.146-151
• /
• 2011

LPG(Liquified Petroleum Gas) fuel for vehicles has lots of advantages such as low emission level, cheaper fuel cost and enough infrastructure. Therefore it arouses interest as an alternative engine to reduce emission of diesel engines. Especially MPI(Multi Point Injection) type LPLi(Liquid Phase LPG injection) system could have overcome the disadvantages of mixer types such as low engine performance, decreased charging efficiency and cold starting difficulty. However ice formation on the nozzle tip and intake port due to the freezing of moisture around the components is often observed in LPLi systems. This icing phenomenon is the direct cause of unstable engine combustion, resulting in engine emissions. Therefore in this research, a spray visualization test for LPG injection was carried out to obtain the basic information of an LPLi injector, then the effects of butane and propane mixing rates on ice formation at the intake port and nozzle tip was investigated. As a result, the icing characteristics of them showed contrary results according to the mixing rates.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 1997.11a
• /
• pp.305-310
• /
• 1997

There are many parameters in prediction of forest fire spread. The variables such as fuel moisture, fuel loading, wind velocity, wind direction, relative humidity, slope, and solar aspect have important effects on fire. Particularly, wind and slope factors are considered to be the most important parameters in propagation of forest fire. Generally, slope effect cause different wind distribution in mountain area. However, this effect is disregarded in complex geometry. In this paper, wind is estimated by applying computational fluid dynamics to the forest geometry. Wind velocity data is obtained by using CFD code with Newtonian model and slope is calculated with geometrical data. These data are applied fer 2-dimentional forest fire spreading algorithm with Korean ROS(Rate Of Spread). Finally, the comparison between the simulation and the real forest fire is made. The algorithm spread of forest fire will help fire fighter to get the basic data far fire suppression and the prediction to behavior of forest fire.

• Journal of Energy Engineering
• /
• v.23 no.3
• /
• pp.235-240
• /
• 2014

In this study, the torrefaction of food waste was conducted to characterize its product, to find out effect of the operating temperature and to assess the feasibility of being used as fuel. The operating temperature was varid from $180^{\circ}C{\sim}270^{\circ}C$ and heat was provided by using nitrogen gas or waste oil heat carrier. The solid yield and moisture content were reduced were reduced as temperature increased. The moisture content reduction and thermochemical conversion were observed at higher than $240^{\circ}C$. At low operating temperature, heat transfer efficiency was higher with wast oil heat carrier. As temperature increases, there was not difference in heat transfer efficiency of two different heating methods. The lower heating value product was increased from 660 to 6,400 Kcal/kg with nitrogen gas and 6,890 Kcal/kg with waste oil heat carrier. The elemental analysis indicates that, as temperature increases, the carbon content of product increases and oxygen content decreases. From the analysis of O/C and H/C, the torrefaction product was close to low grade coal. The characteristics of fuel converted from the food subsequent thermochemical treatment.

• Clean Technology
• /
• v.22 no.4
• /
• pp.286-291
• /
• 2016

In this study we made fuel pellet from miscanthus biomass and investigated changes of physiological characteristics and electricity consumption of pelletizing process in comparison with fuel pellet made of pine sawdust. We also examined combustion characteristics including ash content and clinker forming ratio with fuel pellet made of mixing with micanthus biomass and lime powder. Bulk density of ground-miscanthus and pine sawdust were $158g\;L^{-1}$ and $187g\;L^{-1}$, respectively. Bulk density of ground miscanthus was lower than that of pine sawdust, but increased to $653g\;L^{-1}$ after pelletizing, which was similar to $656g\;L^{-1}$ of pine sawdust pellet. Moisture content in raw miscanthus and ground miscanthus were 17.0% and 11.8%, respectively. Moisture content in ground miscanthus was similar to that of pine saw dust and decreased to 6.73% after pelletizing, which was 7.7% lower than that of pine sawdust pellet. Although $27kWh\;ton^{-1}$ were required for compaction press that was an additional process in miscanthus pelleitizing, total required electricity was $193kWh\;ton^{-1}$ which was similar to $195kWh\;ton^{-1}$ of pine sawdust pellet pelleitizing. Pellet durability and pelletizing ratio of miscanthus were 98.0% and 99.7%, respectively, which were similar to 98.1% and 99.4% of pine sawdust pellet. When lime mixing ratio increased, ash melting degree and clinker forming ratio of miscanthus pellet increased. While higher heating value and clinker forming ratio of miscanthus pellet decreased.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.19 no.1
• /
• pp.73-83
• /
• 2016

Forest degradation reduces ecosystem services provided by forest and could lead to change in composition of species. In North Korea, there has been significant forest degradation due to conversion of forest into terrace fields for food production and cut-down of forest for fuel woods. This study analyzed the phenological changes in North Korea, in terms of vegetation and moisture in soil and vegetation, from March to Octorber 2013, using MODIS (MODerate resolution Imaging Spectroradiometer) images and indexes including NDVI (Normalized Difference Vegetation Index), NDSI (Normalized Difference Soil Index), and NDWI (Normalized Difference Water Index). In addition, marginal farmland was derived using elevation data. Lastly, degraded terrace fields of 16 degree was analyzed using NDVI, NDSI, and NDWI indexes, and marginal farmland characteristics with slope variable. The accuracy value of land cover classification, which shows the difference between the observation and analyzed value, was 84.9% and Kappa value was 0.82. The highest accuracy value was from agricultural (paddy, field) and forest area. Terrace fields were easily identified using slope data form agricultural field. Use of NDVI, NDSI, and NDWI is more effective in distinguishing deforested terrace field from agricultural area. NDVI only shows vegetation difference whereas NDSI classifies soil moisture values and NDWI classifies abandoned agricultural fields based on moisture values. The method used in this study allowed more effective identification of deforested terrace fields, which visually illustrates forest degradation problem in North Korea.

• Korean Chemical Engineering Research
• /
• v.52 no.1
• /
• pp.58-62
• /
• 2014

Electrochemical ammonia synthesis from water and nitrogen using a Pt/GDC/Pt cell was experimentally investigated. Electrochemical analysis and ammonia synthesis in the moisture-saturated nitrogen environment were performed under the operating temperature range $400{\sim}600^{\circ}C$ and the applied potential range OCV (Open Circuit Voltage)-1.2V. Even though the ammonia synthesis rate was augmented with the increase in the operating temperature (i.e. increase in the applied current) under the constant potential, the faradaic efficiency was decreased because of the limitation of dissociative chemisorption of nitrogen on the Pt electrode. The maximum synthesis rate of ammonia was $3.67{\times}10^{-11}mols^{-1}cm^{-2}$ with 0.1% faradaic efficiency at $600^{\circ}C$.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.11a
• /
• pp.75.2-75.2
• /
• 2010

Polymer electrolyte fuel cells (PEFCs) have received a lot of attention as a power source for both stationary and mobile applications due to their attractive feature. In general, the performance of PEFCs is highly affected by the property of the electrodes. A PEFC electrode essentially consists of a gas diffusion layer and a catalyst layer. The gas difusion layer is highly porous and hydrophobicized with PTFE polymer. The catalyst layer usually contains electrocatalyst, proton conducting polymer, even PTFE as additive. Particularly, the proton conducting ionomer helps to increase the catalytic activity at three-phase boundary and catalyst utilization. Futhermore, it helps to retain moisture, resulting in preventing the electrodes from membrane dehydration. The most widely used proton conducting ionomer is perfluorinated sulfonic acid polymer, namely, Nafion from DuPont due to its high proton conductivity and good mechanical property. However, there are great demands for alternative ionomers based on non-fluorinated materials in terms of high temperature availability, environmental adaptability and production cost. In this study, the electrodes with the various content of the sulfonated poly(ether sulfone) ionomer in the catalyst layer were prepared. In addition, we evaluated electrochemical properties of the prepared electrodes containing the various amount of the ionomers by using the cyclic voltammetry and impedance spectroscopy to find an optimal ionomer composition in the catalyst layer.