• Title/Summary/Keyword: 연소효율

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A Theoretical Study on Burning Area of Wire-Embedded Propellant Grains (금속선 삽입 추진제 그레인 연소면적에 대한 이론적 연구)

  • 오종윤
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 1998.04a
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    • pp.32-32
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    • 1998
  • 고체 로켓 모타 추진제 그레인은 크게 단면 연소형 그레인(end-burning grain)과 내면 연소성 그레인(perforated grain)으로 분류할 수 있다. 단면 연소형 그레인은 부피충전율이 크고 구조적 안전성이 우수한 장점이 있으나 연소면적이 작은 단점이 있고, 내면 연소형 그레인은 연소면적이 큰 장점이 있으나 부피 충전율이 작은 단점이 있다. 따라서 단면 연소형 그레인의 장점인 높은 충전율을 유지하면서 연소면적을 증대시키는 효율적인 방법으로 열전도율이 높은 금속선을 단면 연소 그레인에 삽입시키는 방법이 있다. 높은 열전도율로 인하여 금속선을 따라 연소속도가 빨라져 연소면적이 증가하게 되는데, 금속선이 없을 때의 연소속도와의 비를 연소속도 증가 비라 한다. 이는 추진제 종류, 금속선 재질, 굵기 등에 따라 달라지고, 실험실에서 strand burner test로 구할 수 있다.

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Analysis on the Heat Exchange Efficiency of Kraft Recovery Boiler by Nose Arch Structure Using CFD (CFD를 활용한 크래프트 회수보일러 내부 노즈 아치 구조에 따른 열교환 효율 분석)

  • Jang, Yongho;Park, Hyundo;Lim, Kyung pil;Park, Hansin;Kim, Junghwan;Cho, Hyungtae
    • Applied Chemistry for Engineering
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    • v.32 no.2
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    • pp.149-156
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    • 2021
  • A kraft recovery boiler produces steam for power generation by the combustion of black liquor from the kraft pulping process. Since saturated steam became superheated in a superheater above the furnace, it is important to increase the heat exchange efficiency for the superheated steam production and power generation. A nose arch at the bottom of the superheater is important for blocking radiation from the furnace which causes corrosion of the superheater. But the nose arch is the main reason for creating a recirculation region and then decreasing the heat exchange efficiency by holding cold flue gas after the heat transfer to saturated steam. In this study, the size of recirculation region and the temperature of flue gas at the outlet were analyzed by the nose arch structure using computational fluid dynamics (CFD). As a result, when the nose arch angle changed from 106.5° (case 1) to 150° (case4), the recirculation region of flue gas decreased and the heat exchange efficiency between the flue gas and the steam increased by 10.3%.

Development of Sub-scale Combustor for a Liquid Rocket Engine Using Swirl Injector with External Mixing (외부혼합 와류분사기를 장착한 액체로켓엔진용 축소형 연소기 개발)

  • Han, Yeoung-Min;Kim, Seung-Han;Seo, Seong-Hyeon;Lee, Kwang-Jin;Kim, Jong-Gyu;Seol, Woo-Seok
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.32 no.10
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    • pp.102-111
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    • 2004
  • The procedure of design and manufacture of sub-scale combustor using bipropellant swirl injector with external mixing for a liquid rocket engine are described. The results of cold flow test, ignition test and combustion test of the sub-scale combustor are also given in this paper. The sub-scale combustor uses liquid oxygen(LOx) and kerosene as propellants and has a injector head, an ablative material combustor wall and a water cooled nozzle. The injector head has LOx manifold, fuel manifold, fire face plate, one center swirl injector and 18 main swirl injectors. The cold flow, ignition and combustion tests were successfully performed without damage of combustor. Results of hot firing tests show that combustion efficiency meets the target of design and operations of start and stop cyclogram are stable and high frequency combustion instability does not occur.

Measurement of NO in Lean Burn and Soot Flame (희박화염과 매연화염의 NO 계측)

  • 손성민;고동섭;오승묵;강건용;김종욱
    • Proceedings of the Optical Society of Korea Conference
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    • 2001.02a
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    • pp.108-109
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    • 2001
  • 환경문제에 대한 인식이 높아지면서 각종 연소장치의 배출가스에 대한 규제치가 강화되고 있어서, 연소현상 연구는 연소효율 향상과 같은 경제적 측면뿐만이 아니라 환경오염의 해결 관점에서도 그 필요성이 요구되어, 이미 오래 전부터 연소과정의 연구가 활발하게 진행되어 왔다. 그러나 연소현상은 물리·화학적으로 빠르고 복잡한 반응과정을 수반하여 진행하므로, 레이저 분광학적 방법이 주로 계측수단으로 사용되고 있다. (중략)

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가스터빈 연소기에서 난류 생성기를 장착한 선회기의 연소 현상

  • 류승협;손창현;이충원;이근선
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2000.11a
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    • pp.14-14
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    • 2000
  • 가스터빈 연소기의 연소 효율을 높이기 위해서는 연료와 공기의 충분한 혼합이 필요하다. 연료와 흡입되는 공기의 혼합은 큰 스케일의 난류 성분보다는 오히려 연소기내에서 국부적으로 작용하는 작은 스케일의 난류 성분에 크게 지배를 받게된다. 이러한 혼합 촉진을 위해 연료와 공기의 경계면에서의 운동에너지를 증가시키는 방법은 압력의 손실을 가져오게 되지만 혼합의 촉진에 의한 완전연소와 저 NOx화는 더 큰 이익을 가져다 준다.(중략)

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Fluidic Characteristics of Precessing Jet Nozzle Combustor (세차제트노즐 연소기의 유동특성)

  • Lee, Hye-Young;Huh, Hwan-Il
    • Journal of the Korean Society of Propulsion Engineers
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    • v.11 no.4
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    • pp.1-9
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    • 2007
  • Many processing companies are facing environmental regulations such as decreasing NOx emissions when they by to increase thermal efficiencies of combustor. We study a potential new method that may achieve both increase of thermal efficiency and decrease of NOx emissions. This new concept of burner, the precessing jet burner, is known to significantly reduce pollutants such as NOx emissions and simultaneously increase radial heat transfer. This precessing jet nozzle may increase the combustion efficiency of gas turbine engine. A basic research on characteristics of precessing jet nozzle has been conducted using FLUENT and laser visualization technique. Velocities at He nozzle cross-section are compared with the published experimental results. Precessing jet nozzle with centerbody results in better precessing phenomena.

Thermal Barrier Efficiency and Endurance of Ni-Cr Coating in Liquid Rocket Engine Combustor (액체로켓엔진 연소기에 적용된 니켈-크롬 코팅의 열차폐 효율과 내구성)

  • Lee, Kwang-Jin;Lim, Byoung-Jik;Kim, Jong-Gyu;Han, Yeoung-Min;Choi, Hwan-Seok
    • Aerospace Engineering and Technology
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    • v.8 no.1
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    • pp.138-143
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    • 2009
  • Thermal barrier efficiency and endurance of coatings in liquid rocket engine combustor were evaluated for air plasma spray coating and electro/electroless plating. The result of firing tests has revealed occasional occurrence of local delamination of $ZrO_2$, NiCrAlY coating obtained by the method of air plasma spray in the region of supersonic flow and it necessitated a new coating method as a substitution. It was found that Ni-Cr coating by means of electro/electroless plating can substitute $ZrO_2$, NiCrAlY coatings of air plasma spray in terms of thermal barrier efficiency and endurance.

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Comparison of Combustion Efficiency of Multi Hole Pintle Injector and Continuous Pintle Injector (다중 홀 핀틀 인젝터와 연속형 핀틀 인젝터의 연소성능 비교)

  • Nam, JeongSoo;Lee, KeonWoong;Koo, JaYe
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.50 no.3
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    • pp.165-172
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    • 2022
  • Pintle injector is the most suitable injector for thrust control because it can control the area of propellant injection. Accordingly, the combustion test of multiple hole pintle injector and continuous type pintle injector was carried out in this paper using liquid oxygen and gas methane. The combustion performance of the two pintles was verified with the characteristic speed efficiency, and the experimental results were compared according to the O/F and combustion chamber pressure and under similar conditions. The efficiency of the multi hole pintle was generally somewhat higher than continuous pintle when pintle opening distance(the area of dispensing oxidizer) was in a 100% thrust condition.

Formation of Oxy-Fuel MILD Combustion under Different Operating Conditions (가동조건 변화에 따른 순산소 마일드 연소 형성 연구)

  • Lee, Pil Hyong;Hwang, Sang Soon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.40 no.9
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    • pp.577-587
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    • 2016
  • Although the formation of oxy-fuel MILD combustion is considered one of the promising combustion technologies for high thermal efficiency, low emissions and stability have been reported as difficulties. In this paper, the effect of combustor geometry and operating conditions on the formation of oxy-fuel MILD combustion was analyzed using numerical simulation. The results show that the high temperature region and average temperature decreased due to an increase in oxygen inlet velocity; moreover, a high degree of temperature uniformity was achieved using an optimized combination of fuels and an oxygen injection configuration without external oxygen preheating. In particular, the oxy-fuel MILD combustion flame was found to be very stable with a combustion flame region at equivalence ratio 0.90, fuel velocity 10 m/s, oxygen velocity 200 m/s, and nozzle distance 33.5 mm.

Thermal Decomposition and Combustion Behavior of Plastics into Blast Furnace (플라스틱의 高爐 吹入時 熱分解特性 및 燃燒擧動)

  • 허남환;백찬영;임창희
    • Resources Recycling
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    • v.9 no.6
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    • pp.15-22
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    • 2000
  • There are many intensive efforts to develop the recycling technologies of waste plastics in steel works to tackle the saving of resources and the protection of the natural environment. In this study, the thermogravimetric analyses for three kinds of plastics, the combustion experiments and the theoretical approach for calculating the flame temperature in the blast furnace had been performed to understand the behavior of plastics in the raceway. The thermal decompositions of plastics were studied using thermogravimetric analyzer under the atmospheric condition. The starting temperature of thermal decomposition and the maximum weight loss point were increased in proportion to the logarithmic values of heating rate. The combustion characteristics of plastics were simulated in a coke-bed combustor. The combustion efficiency of plastics was lower than that of pulverized coal. The oxygen enrichment was found out to be one of the useful methods to increase the combustibility of plastics in raceway. The maximum injection rate of plastics was calculated based on the flame temperature.

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