• 한국수소및신에너지학회논문집
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• 제20권5호
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• pp.439-446
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• 2009

This paper investigates the dehydration and RDF (Refuse Derived Fuel) production of organic wastes, livestock manure and sewerage sludge with pressurized hydrothermal treatment process. The renewable technology for the organic wastes must involve short treatment time required, reusable energy source, anti-odor and viruses, low cost for the treatment, and well-fertilization. The pressurized hydrothermal treatment process promotes to evaporate moisture in the waste after being shortly treated in a reactor, which uses steam and heat supplied by an external boiler. By the pressurized steam, the cell walls of the waste break and effectively release the internal moisture. Then, the dried waste can be mixed with waste vinyls to produce RDF with a higher heating value as high as 6,700 kcal/kg.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
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• pp.218-222
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• 2006

Due to the high density and heating value, liquid fuel is attractive for ramjet propulsion system. Liquid fuel requires time to evaporation and mix with incoming air before ignition; insufficient evaporation and mixing result in low combustion efficiency and instability. So the numerical studies are conducted to investigate the spray and combustion characteristics of a liquid-fueled dump type Ramjet combustor. The governing equations are solved by means of a finite-volume using time derivative preconditioning method for chemical reacting flow. The liquid phase is treated by solving Lagrangian equations of motion and transport for the life histories of a statistically significant sample of individual droplets.

• 한국농공학회논문집
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• 제59권5호
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• pp.17-23
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• 2017

In South Korea, 25 % of annual agricultural residues (11.64 million tons) are unused. The hydrophilicity, low lower heating value (LHV), and low energy density of agricultural residues can be obstacles for efficient usage. Torrefaction, a low temperature pyrolysis process, can be a solution to overcome these disadvantage of agricultural residues. In this study, agricultural residues such as bean stem, pepper stem, perilla stem, sorghum stem, acorn shell, and ginkgo shell are torrefied at 200, 230, and $250^{\circ}C$ and evaluated energy properties, respectively. The torrefaction can increase the LHV and energy density rate of agricultural residues from 3,331~4,444 kcal/kg to 4,166~5,830 kcal/kg and 20~30 %, respectively.

• 에너지공학
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• 제23권3호
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• pp.235-240
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• 2014

본 연구에서는 음식물쓰레기를 반탄화 하여 생성된 생성물의 특성 및 온도에 대한 영향을 비교하여 연료화 가능성을 파악하고자 하였다. 반응온도를 $180^{\circ}C{\sim}270^{\circ}C$ 조절하고 열전달방식을 질소가스 열전달방식과 열매체유 열전달방식으로 나누어 실험한 결과 생성물의 생산 수율과 수분함량은 온도가 높아짐에 따라 감소하였고 특히 $240^{\circ}C$이상에서는 수분감소 뿐만 아니라 열적변화도 확인 할 수 있었다. 반응온도가 낮을수록 열매체유 열전달방식이 수분감소에 더 좋은 열전달 효율을 보였지만 온도가 높아질수록 그 차이는 미미한 것을 확인할 수 있었다. 발열량의 경우 초기 660 Kcal/kg 에서 질소가스 열전달방식 6,400 Kcal/kg 간접방식 6,890 Kcal/kg 으로 상승 되었고, 원소분석결과 반응온도가 상승할수록 반탄화 생성물의 탄소원소의 함량증가와 산소원소 함량 감소를 확인 하였으며 석탄밴드 분석결과 저급석탄에 가까운 H/C와 O/C의 범위를 나타내었다. 음식물쓰레기를 반탄화를 통하여 연료개질이 가능하다는 것을 확인 할 수 있었으며, 반응온도가 높아질수록 저급석탄에 더 가까워짐을 확인할 수 있었다.

• 에너지공학
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• 제23권4호
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• pp.9-18
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• 2014

시험방법 중 현재 국내 자동차 연비계산 방법은 차대동력계에 시험차량을 설치한 후, 주어진 시험모드(FTP-75 & HWFET 모드 등)에 따라 차량을 주행하여 측정되어지는 배출가스 결과를 가지고 계산에 의해 연비를 구하는 방식인 카본발란스 측정법(Carbon balance method)을 이용하고 있다. 이때 사용하고 있는 카본발란스 측정법은 시험방법 개발 당시의 표준연료에 대해 연료물성을 구하고, 이때 구하여진 상수 값과 시험에서 측정되어진 THC, CO, $CO_2$ 값을 가지고 계산하게 된다. 그러므로 시험할 때마다 매번 바뀌게 되는 사용 연료의 연료물성 특성은 정확히 고려되지 않게 된다. 주어진 시험연료에 따라 엔진성능 및 배출가스 결과가 변하게 되고, 많은 대체연료가 나오고 있는 현 시점에서 시험연료의 물성 특성을 연비계산 시에도 고려해야만 된다고 생각된다. 본 연구에서는 기존에 사용하고 있는 카본발란스법과 실제 시험에 사용된 연료의 유량을 측정하는 유량측정 방법을 이용한 결과를 비교하여, 시험에 사용된 연료의 물성 특성을 고려할 수 있는 방법을 연구함으로서, 다양해지고 있는 연료의 물성 특성을 고려해 줄 수 있는 개선된 연비측정 방법을 검토해 보고자 한다.

• 한국수소및신에너지학회논문집
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• 제12권3호
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• pp.169-176
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• 2001

The purpose of study is to obtain low-emission and high-efficiency in LPG engine with hydrogen enrichment. The test engine was named heavy-duty variable compression ratio single cylinder engine (VCSCE). The fuel supply system provides LPG/hydrogen mixtures based on same heating value. Various sensors such as crank shaft position sensor (CPS) and hall sensor supply spark timing data to ignition controller. Displacement of VCSCE is $1858.2cm^3$. VCSCE was runned 1400rpm with compression ratio 8. Spark timing was set MBT without knocking. Relative air-fuel ratio(${\lambda}$) of this work was varied between 0.76 and 1.5. As a result, i) Maximum thermal efficiency occurred at ${\lambda}$ value 1.0. It was shown that thermal efficiency was increased approximately 5% with hydrogen enrichment at same ${\lambda}$ value. ii) Engine-out carbon monoxide (CO) emissions were decreased at a great rate under LPG/hydrogen mixture fuelling. iii) Total hydrocarbon (THC) emission was much exhausted in rich zone, same as CO. But THC was exhausted a little bit more in lean zone. iv) Finally, engine-out oxides of nitrogen (NOx) was increased with ${\lambda}$ value 1.0 zone at a greater rate with hydrogen enrichment due to high adiabatic flame temperature.

• 유기물자원화
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• 제16권3호
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• pp.65-74
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• 2008

본 연구에서는 서로다른 4지역의 도시 생활 쓰레기의 성상 및 물리 화학적 조성을 조사 하였다. 생활 쓰레기 연료화시설 설치 및 자료확보 차원 매립장 관리차원에서 매우 필요한 연구이다. 평균 밀도는 $79{\sim}199.8kg/m^3$ 범위내의 결과를 얻었다. 생활 쓰레기는 8.87%의 음식물류, 38.8%의 종이류, 34.12%의 플라스틱류 및 비닐류, 7.16%의 섬유류, 0.96%의 목재류 1.3%의 고무 및 가죽류 등으로 구성되어 있다. 생활쓰레기의 대부분은 음식물, 종이류, 플라스틱류 등으로 이루어져 있으며 94% 정도가 가연 성분이다. 삼성분 분석에서는 17.38%의 수분 및 69.03%의 가연분 그리고 6.24%의 회분으로 이루어져 있다. 원소분석결과는 탄소 산소 수소 순으로 이루어져 있다. 생활쓰레기의 저위 발열량은 2973.8kcal/kg 이며 고위 발열량은 5209.94 kcal/kg 결과를 얻었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.451-454
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• 2009

Production and application of biodiesel are expected to grow steadily in the coming years and thus output of its by-product, crude glycerin, will accordingly increase as well. In the present study, gasification of biodiesel by-product as a renewable energy was performed in an entrained flow gasifier to investigate the gasification performance with the operating conditions. Crude glycerin shows a high heating value of 6,000 kcal/kg and low ash and sulphur content. Gasification was conducted in a temperature range of $950\;{\sim}\;1500\;^{\circ}C$. The variation of syngas composition with excess air ratio of 0.17 ~ 0.7 for air or oxygen as a gasification agent was investigated. From the results, syngas heating value, carbon conversion and cold gas efficiency of more than $2500\;kcal/Nm^3$, 95% and 65% were achieved, respectively. The temperature dependency of syngas composition, carbon conversion, and cold gas efficiency shows a similar tendency to excess air ratio at the temperature corresponding to the excess air ratio. The $H_2/CO$ ratio of the product gas was varied from 1.25 to 0.7 with the excess air ratio and this gas composition was favorable for DME synthesis. The optimum excess air ratio for gasification of biodiesel by-product was evaluated to be an approximately 0.35 to 0.4. The present results indicate that crude glycerin can be utilized as a feedstock for gasification to make syngas.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.221-224
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• 2008

We made densified wood pellet by hemp woody core as replacing wood resource. Hemp was separated into the bast fiber and the woody core by hot steaming treatment. The hemp woody core had a similar lignin content and carbohydrate composition with hardwood. Also, the hemp had a low ash content, which resulted in a low ash formation in pellet burning. Heating value of the hemp pellet had a very similar to the pellet made by hardwoods. The hemp woody core can replace hardwood for densified wood pelletmaking.

• 한국수소및신에너지학회논문집
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• 제13권4호
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• pp.297-303
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• 2002

The purpose of study is obtaining low-emission and high-efficiency in LPi engine with hydrogen enrichment. The test engine was named variable compression ratio single cylinder engine (VACRE). The fuel supply system provides LPG/hydrogen mixtures based on same heating value. A varied sensors such as crank shaft position sensor (CPS) and hall sensor supplies spark timing data to ignition controller. Displacement of VACRE is $1858.2cm^3$. VACRE was runned 1400rpm with compression ratio 8. Spark timing was set MBT without knocking. Relative air-fuel ratio($\lambda$) of this work was varied between 0,8 and 1.5.