과산화수소 단일추진제 추력기의 예열 특성 연구

장동욱(Dongwook Jang),강신재(Shinjae Kang),이성민(Sungmin Lee),조성권(Sungkwon Jo),권세진(Sejin Kwon) 한국추진공학회 2014 한국추진공학회 학술대회논문집 Vol.2014 No.5

우주 환경에서 단일추진제 추력기의 운용조건 확립하기 위하여 과산화수소를 이용한 단일추진제 추력기의 예열 조건에 대한 연구를 진행하였다. 실험에 사용된 추력기는 진공 50 N의 추력기를 사용하였고 촉매는 망간촉매 그리고 90 wt% 의 과산화수소를 추진제로 사용하였다. 실험은 예열을 하지 않은 냉시동 시험과 50 °C 부터 50 °C 간격으로 250 °C 까지 촉매베드를 가열하는 예열 시동 시험을 진행하였다. 실험 결과 예열을 한 경우 150 °C 까지는 응답특성과 압력 불안정성이 향상되었다. 하지만 150 °C 이상 예열할 경우에는 150 °C 로 예열했을 때와 큰 차이를 보이지 않았다. 따라서 과산화수소 단일추진제 추력기의 적정 예열 온도는 150 °C 근처로 추정된다. In order to establish operation condition of hydrogen peroxide monopropellant thruster in space environment, preheating characteristics research of monopropellant thruster was conducted. Thruster using in this research was 50 N class in vacuum condition and catalyst was manganese oxide catalyst and propellant was 90 wt% rocket grade hydrogen peroxide. The test cases are non-preheating case and preheating cases that the thruster was preheated from 50 °C to 250 °C at intervals of 50 °C. In the results, the pressure instability and response time sharply decreased until 150 °C in preheating case. However, there were not significant difference between preheating over 150 °C cases and preheating 150 °C case. Therefore, the proper preheating temperature of hydrogen peroxide monopropellant thruster using manganese oxide catalyst was estimated around 150 °C.

온도와 수압이 가곡광산 화강암과 석회암의 물성에 미치는 영향

윤용균(Yongkyun Yoon),백영준(Youngjun Baek),조영도(Youngdo Jo) 한국암반공학회 2011 터널과지하공간 Vol.21 No.1

본 연구에서는 온도와 수압이 암석의 물성 변화에 미치는 영향을 평가하였다. 온도가 암석의 물성에 미치는 영향을 평가하기 위하여 가곡광산에서 채취한 화강암과 석회암 시험편에 200, 300, 400, 500, 600, 700℃(석회암의 경우 700℃는 제외하였음)의 열을 가하여 예열시험편을 제작하였다. 예열시험편에 대한 실내실험을 통해 비중, 유효공극률, 탄성파속도, 일축압축강도, 탄성계수, 포아송비를 측정한 결과 온도가 증가함에 따라 화강암과 석회암 예열시험편의 물성이 변하는 것으로 나타났다. 비중, 유효공극률, 탄성파속도의 급격한 변화는 화강암의 경우 400℃ 이상에서 발생하였으며, 석회암의 경우에는 300℃ 이상에서 나타났다. 온도에 따른 일축압축강도, 탄성계수, 포아송비의 변화도 물리적 특성의 변화와 유사한 것으로 나타났다. 예열시험편의 일축압축강도와 탄성계수로부터 유추한 500, 600, 700℃ 화강암 예열시험편의 GSI는 각기 81, 66, 58로 나타났으며, 400, 500, 600℃ 석회암 예열시험편의 GSI는 각각 76, 71, 65로 나타났다. 500, 600, 700℃ 화강암 예열시험편과 400, 500, 600℃ 석회암 예열시험편에 7.5 ㎫의 수압을 가하였다. 수압을 적용한 예열시험편의 유효공극률, 탄성파속도, 일축압축강도, 탄성계수를 측정하여 평균한 결과 수압을 가하기 전 예열시험편에 비해 평균 감소량이 화강암 500, 600, 700℃ 예열시험편 각각에 대해서 7.6, 11.3, 14.9%로 나타났고, 석회암 400, 500, 600℃ 예열시험편에 대해서는 각기 8.2, 13.8, 21.9%로 평가되었다. This study focuses on having a temperature and water pressure effects on the change of material properties of rocks. Granite and limestone specimens from Gagok Mine were thermally treated with predetermined temperatures of 200, 300, 400, 500, 600 and 700℃ (excepting 700℃ for limestone) to estimate the reduction of material properties of rocks caused by heat. Specific gravity, effective porosity, elastic wave velocity, uniaxial compressive strength, Young’s modulus and Poisson's ratio for pre-heated specimens were measured. With increasing temperature, material properties of both rock specimens change sequentially. Significant changes of specific gravity, effective porosity and elastic wave porosity occur above 400℃ for granite and 300℃ for limestone. Changes of uniaxial compressive strength, Young’s modulus and Poisson’s ratio seem to be similar to those of physical properties. GSI of 500, 600 and 700℃ specimens inferred by using uniaxial compressive strength and Young's modulus of preheated granite specimens is found to be 81, 66 and 58 each. In case of pre-heated limestone specimens of 400, 500 and 600℃, the corresponding GSI is 76, 71 and 65 each. 500, 600 and 700℃ granite specimens and 400, 500 and 600℃ limestone specimens were pressurized to 7.5 ㎫ and their effective porosity, elastic wave velocity, uniaxial compressive strength and Young’s modulus were measured. The average value of material properties (mentioned above) of 500, 600 and 700℃ granite specimens under water pressure compared with material properties of non-pressurized pre-heated specimens exhibits the reduction of 7.6, 11.3 and 14.9%, respectively. In case of 400, 500 and 600℃ limestone specimens under water pressure, the average value of material properties decreases by 8.2, 13.8 and 21.9%, respectively.

Bio-drying 공법 활용 공기 투입 및 예열에 따른 음식물류 폐기물 분해 특성 평가

박세용,이원배 유기성자원학회 2022 유기물자원화 Vol.30 No.4

In this study, the efficiency of treatment of moisture and organic matter in food waste was analyzed according to the air blast volume and preheating using the bio-drying method. Te mount of air blast volume and preheating were determined by the evaluation of temperature and CO2 during food waste treatment using the bio-drying method. As a results, the increase in the air blast volume increased the moisture removal efficiency and removal rate, but, lowered the temperature inside the bio-drying by the decease in microbial activity. In order to maintain the activity of microorganisms, it was estimated that it was necessary to inject an appropriate air blast rate according th the properties of the food waste. In this study, the injection of air blast volume at 15L/min was optimal. It was evaluated that the organic matter and water removal rates according to the presence or absence of air preheating, the organic matter removal rate and water removal rate increased by 3-5% when air preheating was not performed. Also, there was no internal aggregation caused by the generation of condensate inside the bio-drying. Therefore, for effective bio-drying of food waste, it is necessary to maintain an appropriate air blast volume to maintain microbial activity, and it is considered that injection through preheating of air is required. 본 연구에서는 Bio-drying 공법 활용한 공기 송풍량 및 예열에 따른 음식물류 폐기물의 수분 및 유기물의처리 효율에 대해 분석하였으며, 음식물류 폐기물 처리 시 온도, CO2의 평가를 통해 공기 송풍량 및 공기 예열이Bio-drying 공법의 미치는 영향에 대해 평가하였다. 그 결과 공기 송풍량의 증가는 수분 제거율 및 제거 속도가증가하는 결과를 미쳤지만, Bio-drying 내부 온도를 저하 시켜 미생물 활성도의 감소를 야기시켰다. 미생물의 활성도유지를 위해서는 음식물류 폐기물의 성상에 따른 적정 공기 송풍량을 주입하는 것이 필요할 것으로 판단되었으며, 본 연구에서는 15L/min으로 주입하였을 때가 최적이었다. 공기 예열 유무에 따른 유기물 및 수분 제거율을 평가한결과 공기 예열을 하였을 때가 하지 않았을 때에 비해 유기물 제거율 및 수분 제거율이 3~5% 가량 증가하는 결과를보였다. 또한 Bio-drying 내부에 응축수 발생에 의한 내부 뭉침 현상도 발견되지 않았다. 따라서, 음식물류 폐기물의효과적인 Bio-drying을 위해서는 미생물 활성도 유지를 위한 적정 송풍량을 유지 해야 하며, 공기 예열을 통한주입이 필요할 것으로 사료된다.

SM520B 강의 예열온도 변화에 따른 용접부 균열에 관한 연구

최용기(Yong-Ki Choi) 산업기술교육훈련학회 2011 산업기술연구논문지 (JITR) Vol.16 No.4

It is easy to initiate the crack at weld zone because thick plate is relatively faster on cooling rate and is higher on confining stresses than thin plate, thus steel materials are becoming thick plate with structures have become bigger along with industrial development. Cold crack is divided into the transverse crack occurred inside weldments and the longitudinal crack induced at heat affected zone, which is comes from diffusible hydrogen, remained stress, susceptible microstructure. It is well known that the susceptible microstructure such as martensite, lower-bainite is overly sensitive to hydrogen assisted cracking in microstructure aspects. In this study, SM 520B steels which are used at construction were butted welded to make comparative study physical properties at welds with variation of preheating temperature. As a result, the preheating effect was a much safer than when no preheating in many ways. In case of no preheating, microstructure is more likely to form bainite which lowers toughness in base metal and weld zone due to fast cooling rate, thus hardness value is much higher as 324Hv compare to 219 Hv when preheating. Moreover, the transverse crack which judged typical cold crack not only generated on surface of weld-bead about 14 to 20mm in length but formed hardening structure at weld.

전기로 조업에 사용되는 철스크랩의 예열온도와 산화특성에 관한 연구

유정민 한국자원리싸이클링학회 2023 資源 리싸이클링 Vol.32 No.4

An eco-friendly, new type of electric arc furnace(EAF) that utilizes its off gas to preheat the iron scrap, the primary raw material of the furnace, has been recently developed. Scrap preheating furnaces consume up to 30% less energy than conventional EAFs. This study investigated how the off-gas dust collection rate and the type of scrap used in the recently developed EAF affect the preheating temperature of the scrap and its oxidation rate. A 1/6 linear scale model of the ecological and economical arc furnace(ECOARC) owned by Dongkuk Steel was constructed and tested. Steel scrap was charged into the preheating shaft of the EAF and preheated using its off-gas. The scrap preheating temperature depended on the off-gas dust collection rate and type of scrap used. It increased in the order of turnings, lightweight scrap, shredded scrap and heavy scrap. The scrap oxidation rate also depended on the type of scrap used and increased in the same order as the scrap preheating temperature. At the preheating temperature of the turnings, the oxidation rate of the scrap was almost of turnings fed to the newly developed EAF, the ratio of carbon to oxygen within it can be controlled.

급탕예열시스템에 적용한 PVT 패널의 성능에 관한 연구

이근휘(Keunhui Lee),곽재호(Jaeho Kwak) 한국태양에너지학회 2018 한국태양에너지학회 학술대회논문집 Vol.2018 No.4

다단사이클론 예열기와 예소성로 내부 유동장 수치모사

김우태(Woo Tae Kim),이구회(Guhoe Lee),허원(Won Heo),오세천(Sea Cheon Oh),송민정(Min Jeong Song) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11

The turbulent flow field inside multistage cyclone preheater and pre-calciner is numerically simulated via the finite volume method. The primary air is supplied through a rotary cement kiln which is connected to the pre-calciner. The steady state velocity field shows that a strong circulating flow pattern is formed in the first and second stage cyclone preheaters. To analyze the blocking effect of solid particles in the pipes attached the cyclone bottom part, the case without the connecting pipes are compared with the reference case with the connecting pipes. As the blockage ratio changes depending on the operating conditions, the simulation results for the two cases provide valuable information for the two extreme situations where the reference case represents non-blocking and the modified case represents complete blocking. The modified case shows the stronger circulating flow in the cyclone preheaters.

소각시설의 예열부하 절감을 위한 다단 열에너지저장 장치의 열 해석 연구

박동호(Dongho Park),정효재(Hyo Jae Jeong),이대규(Daegyu Lee),정동열(Dong-Yeol Chung),강채동(Chaedong Kang) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11

In order to reduce the preheating load for re-operation of incinerators, a thermal energy storage(TES) system that can be charged the heat during normal operation and discharged the heat during re-operation is developed. TES system consists of a cascade heat storage module to store a wide range of temperatures. Heat exchange analysis was performed according to the internal steam pressure and flow rate range to allow heat storage at a temperature range of approximately 60~300℃ and a maximum pressure of 10 bar.

촉매연소기에서 예열온도와 유입농도가 NO_x 저감에 미치는 연구

정진도(Jeong Jin Do),이보영(Lee Bo Yeong) 大韓環境工學會 2003 대한환경공학회지 Vol.25 No.11

강판 예열용 가스토치의 내외부 형상수정에 의한 출구유동균일도 개선

이근식(Geun Sik Lee),고티엔터(Tu Thien Ngo),웬반합(Hap Van Nguyen),고준호(Jun Ho Go) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11

This study focuses on improving the exit flow uniformity of a gas torch with multi-exit holes. Based on the original model, three different models are designed and analysed with aid of CFD software ANSYS FLUENT. The original model has T-shaped configuration with one inlet and multi-exit holes. Model 1 has a long perforated strip with different hole diameters from the center to the right and left ends. Model 2 has a reverse Y-branch(2-symmetric bypass pipes in the inlet region), 2-stage diffuser to the center flow region, and corner cut shape at both ends. Model 3 has an enlarged inlet with triangular shape, a short perforated strip in the center flow region, and corner cut shape at both ends. Flow uniformity(γ) at multi-exit holes(γ=1 means the highest uniform and γ=0 means the lowest uniform) together with velocity distribution was investigated within the Reynolds number ranging from 10,000 to 50,000. Compared with original model to have the flow uniformity ranging from 0.798 to 0.821, the three new models had γ1 = 0.889 - 0.899, γ2 = 0.892 - 0.898 and γ3 = 0.891 - 0.916, respectively. With a pertinent trade-off (between the capital cost to the new design and the operating cost to save the fuel energy and to obtain a good quality for steel preheating), a suitable geometry of gas torch can be drawn.