• Title/Summary/Keyword: Lower Heating Value

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An Experimental Study on the Devolatilization Kinetics of Ashless coal in Fixed and Entrained Conditions (초청정 석탄의 탈휘발 반응률에 관한 실험적 연구)

  • Yu, Da-Yeon;Lee, Byoung-Hwa;Song, Ju-Hun;Lee, Si-Hyun;Jeon, Chung-Hwan
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.10
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    • pp.997-1003
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    • 2011
  • In order to investigate devolatilization characteristics for ashless coal with relatively low ash content and high heating value, an experiment was performed in different bed configurations of TGA and DTF(Drop Tube Furnace) at atmospheric pressure condition. The heating rate was $10^{\circ}C$/min up to $950^{\circ}C$ in TGA, while the temperatures of DTF varied from 500 to $1300^{\circ}C$ in step of $200^{\circ}C$. A weight loss and particle temperature were obtained to determine devolatilization kinetics. The kinetic parameters including an activation energy and pre-exponential factor for ashless coal were obtained using Coats-Redfern method in TGA and single step method in DTF. Furthermore, the devolatilization kinetics of the ashless coal were compared with the results of different kinds of conventional coal such as sub-bituminous and bituminous. The results show that the activation energy of devolatilazation for ashless coal is lower than those of others in fixed and entrained conditions.

Finite Element Analysis on the Strength Safety of a Fuel Tank for Highly Compressed Gas Vehicle (수술실 내의 아산화질소($N_2O$) 노출평가)

  • Baek, Jong-Bae;Uhm, Min-Yong
    • Journal of the Korean Institute of Gas
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    • v.13 no.6
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    • pp.34-38
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    • 2009
  • Nitrous oxide, which is used as an anesthetic gas, has been shown to be a chronic health hazard. It is necessary to monitor and control the nitrous oxide exposure of the operating theaters staff. In this study, N2O exposure level of the operating nurses is assessed with a GC-ECD. The nitrous oxide gas is collected on a molecular sieve 5A contained in a glass tube and desorbed for 12 hours at $100^{\circ}C$ in heating block. As a result of the test using GC-ECD, calibration curve's $R^2$ of $N_2O$ is 0.9992, LOD is $0.96{\mu}g$/injection, LOQ is $3.21{\mu}g$/injection, desorption efficiency is 94.78 4.50% in average and break through is within 10% compared with the concentration. The average concentration before operation is 5.12ppm and it is 42.3ppm during operation. There are a significant difference showing that the P value is lower than 0.05. Assessing exposure level to nitrous oxide based on nurses' working positions, the exposure levels do not show significant difference( P>0.005). And $N_2O$ in active sampling method is higher than passive sampling method(P<0.05).

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Quality Attributes of Whole Soybean flour Tofu Affected by Coagulant and Theirs Concentration (응고제 종류와 농도에 따른 전지대두분 두부의 품질)

  • Kim, Ju-Young;Kim, Jun-Han;Kim, Jong-Kuk;Moon, Kwang-Deog
    • Korean Journal of Food Science and Technology
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    • v.32 no.2
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    • pp.402-409
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    • 2000
  • To investigate the textural and physical characteristics of WSF(whole soybean flour) tofu affected by coagulant and its concentration, $CaCl_2$, $CaSO_4$, $GDL(glucono-{\delta}\;lactone)$, $MgCl_2$, and some mixed coagulants were used in this study. Yields of WSF tofu coagulated with $CaSO_4$ and GDL were ranged 4.3-4.5(g/g WSF), but common tofu was 2.2-3.0(g/g soybean). As the water addition ratio increased, L and a value were increased while heating time increased, b value increased. L value of WSF tofu was lower and b value was higher than conventional tofu and 4 commercial tofus. Kinds of coagulant and its concentration significantly affected to textural properties of WSF tofu. As the concentration of coagulant increase, the hardness increased in most all coagulants. WSF tofu coagulated with $CaSO_4$ and GDL recorded low hardness and adhesiveness, and high springiness among the used coagulants at the same concentration. As the hardness increased, the gumminess and chewiness increased in most all coagulants. As coagulation temperature and molding pressure increase, hardness also increased. WSF tofu coagulated with 0.3% $CaSO_4+GDL$ was the most similar in the textural properties with conventional tofu and 4 commercial tofus. WSF tofu coagulated with 0.3% of $CaSO_4+GDL$ at $85^{\circ}C$, 10 times water addition, 5min. heating and $25.0g/cm^2$ molding pressure recorded the highest score in the sensory evaluation.

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Physicochemical Properties of Oat (Avena sativa) Flour According to Various Roasting Conditions

  • Lee, In-Sok;Song, Young-Eun;Han, Hyun-Ah;Song, Eun-Ju;Choi, So-Ra;Lee, Ki-Kwon
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.62 no.1
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    • pp.32-39
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    • 2017
  • This study was performed to investigate the physicochemical properties of raw and roasted oats for the production of processed goods. Changes in particle size, pH, moisture content, Hunter b value, polyphenols, proteins, flavonoids, lipid rancidity, ${\beta}-glucan$ content and sensory evaluation were compared between raw and roasted hulled oats (HO) and de-hulled oats (DO) after heating treatment at 0, 80, 120, 160 and $200^{\circ}C$. HO was more finely crushed than DO. The Hunter b value of HO was lower than that of DO, which increased sharply at $200^{\circ}C$. The pH range was from 6.2 to 6.6, with an average value of 6.4. In contrast to the protein contents of the two oat types, polyphenol content showed gradual decrease as roasting temperature increased. A comparison of the flavonoid content of HO with DO, indicated difference in the increase of flavonoids with increasing temperature. The protein content of HO was observed to be higher than that of DO. Furthermore, the protein level was slightly increased with increasing temperature. Malonidialdehyde (MDA) content was statistically identical from $0^{\circ}C$ to $160^{\circ}C$, but then increased sharply at $200^{\circ}C$. As expected, the ${\beta}-glucan$ content of HO was higher than that of DO. The ${\beta}-glucan$ content of HO was decreased at $80^{\circ}C$, but increased from $120^{\circ}C$ to $200^{\circ}C$. In contrast, the ${\beta}-glucan$ of DO increased constantly compared to the control. Variations in sensory characteristics such as color, taste, smell and overall preference were observed. There were statistically significant difference among the sensory characteristics of the two oat types heated at $0^{\circ}C$ and $120^{\circ}C$ and at $160^{\circ}C$ and $200^{\circ}C$ (p<0.05). Our collective results, including those for particle size, MDA, protein, ${\beta}-glucan$ content and sensory evaluation, indicated that HO would be more useful in the development of processed goods than DO, and that an optimum temperature for roasting oats is approximately $160^{\circ}C$ for 15 min. Moreover, our results indicate that suitable roasting temperatures and cultivars are necessary to produce high-quality processed oat goods.

Hydrotreating for Stabilization of Bio-oil Mixture over Ni-based Bimetallic Catalysts (Ni계 이원금속 촉매에 의한 혼합 바이오오일의 안정화를 위한 수소첨가 반응)

  • Lee, Seong Chan;Zuo, Hao;Woo, Hee Chul
    • Clean Technology
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    • v.27 no.1
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    • pp.69-78
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    • 2021
  • Vegetable oils, such as palm oil and cashew nut shell liquid (CNSL), are used as major raw materials for bio-diesel in transportation and bio-heavy oil in power generation in South Korea. However, due to the high unsaturation degree caused by hydrocarbon double bonds and a high content of oxygen originating from the presence of carboxylic acid, the range of applications as fuel oil is limited. In this study, hydrotreating to saturate unsaturated hydrocarbons and remove oxygen in mixed bio-oil containing 1/1 v/v% palm oil and CNSL on monometallic catalysts (Ni and Cu) and bimetallic catalysts (Ni-Zn, Ni-Fe, Ni-Cu Ni-Co, Ni-Pd, and Ni-Pt) was perform under mild conditions (T = 250 ~ 400 ℃, P = 5 ~ 80 bar and LHSV = 1 h-1). The addition of noble metals and transition metals to Ni showed synergistic effects to improve both hydrogenation (HYD) and hydrodeoxygenation (HDO) activities. The most promising catalyst was Ni-Cu/��-Al2O3, and in the wide range of the Ni/Cu atomic ratio of 9/1~1/4, the conversion for HYD and HDO reactions of the catalysts were 90-93% and 95-99%, respectively. The tendency to exhibit almost constant reaction activity in these catalysts of different Ni/Cu atomic ratios implies a typical structure-insensitive reaction. The refined bio-oil produced by hydrotreating (HDY and HDO) had significantly lower iodine value, acid value, and kinetic viscosity than the raw bio-oil and the higher heating value (HHV) was increased by about 10%.

Processing and Mechanical Properties of Mullite Fiber / Fe Composite

  • Niibo, Yoshihide;Yuchi, Kazuhiro;Sameshima, Soichiro;Hirata, Yoshihiro
    • Proceedings of the Korea Association of Crystal Growth Conference
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    • 2000.06a
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    • pp.195-214
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    • 2000
  • The high-speed steel (shorten as HSS) consists of Fe and several kinds of transition metal carbides. The cutting tools or wear-resistant materials made from HSS experience relatively high thermal shock because a coolant such as water or oil is flowed over the surface of heated HSS. The purpose of this research is to increase the hardness, strength, fracture toughness and thermal shock resistance of HSS. A possible strategy is to incorporate a hard ceramic material with high strength in HSS matrix. This paper describes the processing, microstructure and mechanical properties of the oriented unidirectional mullite fiber/HSS composite. The unidirectional mullite fibers of 10${\mu}{\textrm}{m}$ diameter were dispersed by the ultrasonic irradiation of 38 kHz in an ethylenglycol suspension containing HSS powder of 11${\mu}{\textrm}{m}$ median size. The dried green composites with 4-68 vol% fibers were hot-pressed for 2h at 100$0^{\circ}C$ in Ar atmosphere under a pressure of 39 MPa. The higher density was achieved in the composite with a lower content of fibers. The oriented unidirectional fibers were well dispersed in the HSS matrix. The average distance between the center of fibers in the cross section was close to the value calculated from the fiber fraction. No reaction occurred at the interfaces between HSS and mullite fibers in the composites. The composite with 13.6 vol% fibers showed 100 MPa of four point flexural strength at room temperature. The thermal expansion of composite with heating was influenced by the orientation of mullite fibers.

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A Study on the solid waste of Buk Han Mt National Park (북한산 국립공원의 고형 폐기물에 관한 연구)

  • 도갑수;장일영;김광진
    • Journal of the Korean Professional Engineers Association
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    • v.19 no.1
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    • pp.12-24
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    • 1986
  • The number of visiters to Bukhan Mt. national park, generation quantity of solid waste and collection system were researched to consider a counterplan for the pollution control of the national park and study for developing the effective treatment of solid waste was tried through the proximate analysis of each component containing. Results obtained in this study were summerized as follows; The great part of visitors go on an excursion to the Bukhan Mt. national park during July and August and also, the solid waste was generated nearly a half of the total amount at the same period. The major collection facilities in the national park were waste basket and incineration box. But the incineration box was too large in volume and very far in distance, and its collection period was irregular, so it was cause to the congestion of solid waste and bad smell and dirty. Therefore, to complete collection of solid waste, we must set up the waste basket which able to find within 40~50m from the origination place of solid waste and induce the visitors to throw the solid waste. It was obtained as moisture content: 48.5 wt%, volatile solid: 28.4wt%, fixed solid: 23.1 wt%, lower heating value: 1,320kca1/kg from experimental analysis of solid waste. According to this analysis, the incineration operation is possible, but the generation quantity of solid waste was too small to construct incineration plant for heat recovery. It was found that it is suitable for the aerobic composting by mixing with the night soil which generate in the national park after the recovery of resources such as metals, glasses and plastics.

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Analysis of Environmental Process for Commercial Rubbers using Thermal Degradation (열분해를 이용한 범용고무의 환경친화적 처리공정 해석)

  • Kim, Won-Il;Lee, Seung-Bum;Hong, In-Kwon
    • Elastomers and Composites
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    • v.35 no.4
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    • pp.272-280
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    • 2000
  • The experimental kinetics was analyzed for commercial rubbers such as NR, IR, BR, SBR 1500, and SBR 1700. Kinetic analysis for the commercial rubbers was performed using a thermogravimetric method, which the activation energies of NR obtained by Kissinger, Friedman, ana Ozawa's method were 195.0, 198.3, and 186.3 kJ/mol, respectively. whereas that of SBR 1500 were 246.4, 247.5, and 254.8 kJ/mol, respectively. It was shown that the yield of pyrolytic oil was generally increased with increasing the final temperature. Considering the effect of heating rate. it was found that the yield of pyrolytic oil was not consistent for each sample. The number average molecular weight of pyrolitic oil of SBR 1500 was in the range of 740-2486. The calorific value of SBR 1500 was 39-40 kJ/g, and it might be a considerable energy potential although it was lower than the conventional fuel such as kerosene, diesel, light fuel, and heavy fuel.

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Basic Study on Oversea Biomass Energy Resources 1 - Palm Biomass (해외 바이오매스 에너지자원 확보를 위한 기초조사 1 - 팜 바이오매스)

  • Lee, Hyoung Woo
    • Journal of the Korean Wood Science and Technology
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    • v.42 no.4
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    • pp.439-449
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    • 2014
  • RPS (Renewable Portfolio Standard) has increased wood pellet demand dramatically in recent years in Korea where self-supply rate of wood pellet is not more than 10%. However global production capacity of wood pellet is prospected to be unable to meet the global demand after 2020. Therefore it is urgently needed to develop new sustainable biomass energy resources which can replace wood pellet at lower cost. As a result of this study EFB (empty fruit bunch) and MF (mesocarp fiber), the representative solid palm biomass, are estimated to be generated at the rate of 20 and 28 million tons per year (based on 10% moisture content) in Malaysia and Indonesia, respectively in 2012. Total annual generation rate of EFB and MF is estimated as 48 million tons per year only in Malaysia and Indonesia in 2012. With calorific value of over 90% of wood pellet EFB is expected to be a excellent biomass energy resource which can replace wood pellet. EFB can be utilized as fuel for power generation or industrial purpose. However EFB may not be a proper fuel for domestic and greenhouse heating because of its high ash content.

Influence of Reaction Parameters on Biocrude Production from Lipid-extracted Microalgae using Hydrothermal Liquefaction (열수액화를 이용한 미세조류 추출잔사로부터 바이오원유 제조에 대한 반응인자의 영향)

  • Ryu, Young-Jin;Shin, Hee-Yong;Yang, Ji-Hyun;Lee, Yunwoo;Jeong, Injae;Park, Hanwool;Lee, Choul-Gyun
    • Journal of Marine Bioscience and Biotechnology
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    • v.9 no.2
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    • pp.35-42
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    • 2017
  • Hydrothermal liquefaction of lipid-extracted Tetraselmis sp. feedstock containing 80 wt.% water was conducted in a batch reactor at different temperatures (300, 325, and $350^{\circ}C$) and reaction times (5, 10, 20, 40, and 60 min). The biocrude yield, elemental composition and higher heating value obtained at various reaction conditions were used to predict the optimum conditions for maximizing energy recovery of biocrude with good quality. A maximum energy recovery of 67.6% was obtained at $325^{\circ}C$ and 40 min with a high energy density of 31.8 MJ/kg and lower contents of nitrogen and oxygen. Results showed that reaction conditions of $325^{\circ}C$, 40 min was most suitable for maximizing energy recovery while at the same time achieving improved quality of biocrude.