• Journal of ILASS-Korea
• /
• v.14 no.4
• /
• pp.147-152
• /
• 2009

Since a liquid-phase LPG injection system allows accurate control of fuel injection and increase in volumetric efficiency, it has advantages in achieving higher engine power and lower emissions compared to the mixer type LPG supplying system. However, this system also leads to an unexpected event called icing phenomenon which occurs when moisture in the air near the injector freezes and becomes frost around the nozzle hole due to extraction of heat from surrounding caused by instant fuel vaporization. As a result, it becomes difficult to control air/fuel ratio in engine operation, inducing exacerbation of engine performance and HC emission. One effort to mitigate icing phenomenon is to attach anti-icing injection tip in the end of nozzle. Therefore, in this study, the effect of engine operation parameters as well as surrounding conditions on icing phenomenon was investigated in a bench test rig with commercially-used anti-icing injection tips. The test results show that considerable ice was deposited on the surface near the nozzle hole of the anti-icing tip in low rpm and low load operating conditions in ambient air condition. This is because acceleration of detachment of deposited ice from the tip surface was induced in high load, high rpm conditions, resulting in decrease in frost accumulation. The results of the bench testing also demonstrate that little or no ice was formed at surrounding temperature below a freezing point since the absolute amount of moisture contained in the intake air is too small in such a low temperature.

• Transactions of the Korean hydrogen and new energy society
• /
• v.23 no.4
• /
• pp.310-315
• /
• 2012

A simple drying process was developed for the preparation of a Pt/Nafion self-humidifying membrane to be used for a proton-exchange membrane fuel cell (PEMFC). Platinum (II) bis (acetylacetonate), $Pt(acac)_2$ was sublimed, penetrated into the surface of a Nafion film and then reduced to Pt nanoparticles simultaneously without any support of a reducing agent in a glass reactor at $180^{\circ}C$ for 15 min. The process was carried out in $N_2$ atmosphere to prevent the oxidation of Pt nanoparticles at high temperature. The morphology and distribution of the Pt nanoparticles were observed by transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS), and we found that the average Pt particle size was ca. 3.7 nm, the penetration depth was ca. $17{\mu}m$. Almost all Pt nanoparticles were formed just beneath the surface and the number density decreased rapidly as the penetration depth increased. To estimate water absorption characteristics of the Nafion membranes, water uptake at an isothermal condition was measured by dynamic vapor sorption (DVS), and it was found that water uptake of the Pt/Nafion membrane was higher than that of the neat Nafion membrane.

• Transactions of the Korean hydrogen and new energy society
• /
• v.28 no.4
• /
• pp.369-376
• /
• 2017

Temperature and humidity regulations of an open-cathode PEM fuel cell with balance of plant (BOP) are developed in this study. The axial fan, a bubble humidifier, set of solenoid valves and a controller are used to perform temperature and humidity control simultaneously. A fuzzy controller is designed, and it shows its superiority in real-time controlling for strong non-linear dynamical fuel cell system. The axial fan speed is used for temperature control and solenoid valve on/off signal of the bubble humidifier is used for humidity control. The axial fan speed is controlled to keep the fuel cell temperature within the desired point. Meanwhile, the bubble humidifier is utilized to moisture hydrogen to manage the water content of membrane. The results show that the proposed fuzzy controller effectively increases the output power of 10% for a PEM fuel cell.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.108.1-108.1
• /
• 2011

This paper proposes the method to develop the fuel of suljigemi pellets using agricultural by-products the occurred during the manufacturing of alcohol. This paper is the goal to make sulgigemi pellet fuel for develops pellet of high calorie. The methods of sulgigemi pellet manufacturing well mix as the dough with the water and the sulgigemi. And then we have dried in the after compression and molding using well mixed the sulgigemi. The moisture of pellets has dried it removed until about 85%. Suljigemi pellet has the effect of zero emission as the soil conditioner using ash after burning. The merits for the sulgigemi pellet are the convenience of storage and custody. Also sulgigemi pellet has the reduction effect of carriage fee, fuel economy and low-cost high-efficiency effects, environmentally clean fuel as CO2 emissions savings. In experiment, we confirmed to calories of the wood pellet and the sulgigemi pellet. The calorie of the suljigemi pellets has high 233 kilo calories than the wood pellets. So the technologies of the sulgigemi fuel pellets are developing low carbon, green growth renewable energy fuel through futuristic energy system will be.

• Environmental Engineering Research
• /
• v.23 no.4
• /
• pp.456-461
• /
• 2018

The solid-state anaerobic digestion (SS-AD) has promoted the development and application for biogas production from biomass which operate a high solid content feedstock, as higher than 15% of total solids. However, the digested byproduct of SS-AD can be used as a fertilizer or as solid fuel, but it has serious problems: high moisture content and poor dewaterability. The organic residue from SS-AD has to be improved to address these problems and to make it a useful alternative energy source. Hydrothermal carbonization was investigated for conversion of the organic residue from the SS-AD of livestock waste to solid fuels. The effects of hydrothermal carbonization were evaluated by varying the reaction temperatures within the range of $180-240^{\circ}C$. Hydrothermal carbonization increased the calorific value through the reduction of the hydrogen and oxygen contents of the solid fuel, in addition to its drying performance. Therefore, after the hydrothermal carbonization, the H/C and O/C atomic ratios decreased through the chemical conversion. Thermogravimatric analysis provided the changed combustion characteristics due to the improvement of the fuel properties. As a result, the hydrothermal carbonization process can be said to be an advantageous technology in terms of improving the properties of organic waste as a solid-recovered fuel product.

• Journal of the Korean Wood Science and Technology
• /
• v.43 no.6
• /
• pp.757-767
• /
• 2015

This study was conducted to investigate the effects of moisture content and particle size of sawdust on the fuel characteristics of wood pellets produced with Mongolian oak (Quercus mongolica, QUM), red pine (Pinus densiflora, PID) and larch (Larix kaempferi, LAK) sawdust using a flat-die pelletizer. Prior to produce wood pellets, the sawdust was controlled to the moisture content of 8, 11, 12% and was screened to the particle size of 2 and 4 mesh. In the analysis of its chemical composition, QUM had a high ash content, and PID and LAK contained large amount of lignin. In case of the fuel characteristics, PID pellets had the lowest moisture content of pellets (P-MC), and LAR pellets was found to have the highest bilk density (BD) and durability (DU). With the increase of moisture content of sawdust (S-MC), P-MC and DU of QUM, PID and LAK pellets increased, but BD of QUM and LAK pellets decreased. When size of sawdust used for the production of wood pellets decreased, P-MC and BD of LAK pellets and BD of QUM pellets increased. Decrease of particle size contributed to the increase of DU of QUM, PID and LAK pellets. In addition, BD and DU of QUM pellets produced with 12% S-MC sawdust increased as its particle size reduced. For LAK pellets, DU was not influence by particle size in the S-MCs of 10% and 12%, but increased with the decrease of particle size in the S-MC of 8%. Based on the results and economical aspects, 10% MC and 2 mesh paricle size for QUM sawdust and 12% MC and 2 mesh particle size for PID sawdust might be optimal conditions for pellets production, and fuel characteristics of wood pellets produced by the conditions greatly exceeded the minimum requirements for the $1^{st}$-grade wood pellets of the standard designated by Korea Forest Research Institute.

• Proceedings of the KSME Conference
• /
• 2008.11b
• /
• pp.2856-2861
• /
• 2008

A catalytic burner has been developed to utilize thermal energy from the fossil fuel without nitrogen oxides (NOx) emission. The burner is shaped into a mat to maximize the heating surface. Premixed combustion has been developed to be used in a closed chamber, such as a radiation type industrial dryer. The burner yields the thermal energy in the form of thermal radiation in the infrared regime, which is proved to be effective to dry organic substances for low moisture condition. Thermal efficiency including the sensible heat is better correlated to the moisture compared to the dry rate.

• 한국방재학회:학술대회논문집
• /
• 2009.02b
• /
• pp.102-102
• /
• 2009

• Journal of the Korean Association of Geographic Information Studies
• /
• v.22 no.3
• /
• pp.21-36
• /
• 2019

Dead fuel moisture content is a key variable in fire danger rating as it affects fire ignition and behavior. This study evaluates simple regression models estimating the moisture content of standardized 10-h fuel stick (10-h FMC) at three sites with different characteristics(urban and outside/inside the forest). Equilibrium moisture content (EMC) was used as an independent variable, and in-situ measured 10-h FMC was used as a dependent variable and validation data. 10-h FMC spatial distribution maps were created for dates with the most frequent fire occurrence during 2013-2018. Also, 10-h FMC values of the dates were analyzed to investigate under which 10-h FMC condition forest fire is likely to occur. As the results, fitted equations could explain considerable part of the variance in 10-h FMC (62~78%). Compared to the validation data, the models performed well with R2 ranged from 0.53 to 0.68, root mean squared error (RMSE) ranged from 2.52% to 3.43%, and bias ranged from -0.41% to 1.10%. When the 10-h FMC model fitted for one site was applied to the other sites, $R^2$ was maintained as the same while RMSE and bias increased up to 5.13% and 3.68%, respectively. The major deficiency of the 10-h FMC model was that it poorly caught the difference in the drying process after rainfall between 10-h FMC and EMC. From the analysis of 10-h FMC during the dates fire occurred, more than 70% of the fires occurred under a 10-h FMC condition of less than 10.5%. Overall, the present study suggested a simple model estimating 10-h FMC with acceptable performance. Applying the 10-h FMC model to the automatic mountain weather observation system was successfully tested to produce a national-scale 10-h FMC spatial distribution map. This data will be fundamental information for forest fire research, and will support the policy maker.

• Journal of the Korean Society of Combustion
• /
• v.18 no.4
• /
• pp.1-11
• /
• 2013

The oxy-fuel combustion is $CO_2$ capture technology that uses mixture of pure $O_2$ and recirculated exhaust as oxidizer. Currently some Oxy-fuel power plants demonstration project is underway in worldwide. Meanwhile research project for converting 125 MWe Young-Dong power plant to 100 MWe oxy-fuel power plants is progress. In this paper, 1 D process analytical approach was applied for conducting process design and operating parameters sensitivity analysis for oxy-fuel combustion of Young-Dong power plant. As a result, appropriate gas recirculation rates was 74.3% that in order to maintain normal rating superheater, reheater steam temperature and boiler heat transfer patterns. And boiler efficiency 85.0%, CPU inlet $CO_2$ mole concentration 71.34% was predicted for retrofitted boiler. The oxygen concentration in the secondary recycle gas is predicted as 27.1%. Meanwhile the oxygen concentration 22.4% and moisture concentration 5.3% predicted for primary recycle gas. As the primary and secondary gas recirculation increases, then heat absorption of the reheater is tends to increases whereas superheater side is decreased, and also the efficiency is tends to decrease, according to results of sensitivity analysis for operating parameters. In addition, the ambient air ingression have a tendency to lead to decline of efficiency for boiler as well as decline of $CO_2$ purity of CPU inlet.