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신재훈,박태준,조현석,유준상,문석수,이창언 한국분무공학회 2023 한국액체미립화학회지 Vol.28 No.1
The waste-heat-recovery boiler with water spray (HR-B/WS) applies the heat exchange between the inlet air and exhaust gas with the water spray into the inlet air. The evaporation of water in the inlet air promotes heat recovery from the exhaust gas so that thermal efficiency can be improved by the enhanced condensing effect. The NOx emission can also be reduced by lowering the flame temperature due to the dilution effect of the water. In this study, the validity of this concept is examined by the practical boiler test performed with a 24 kW condensing boiler under the full load condition according to the water injection amount. The theoretical amount of water injection is calculated under the assumption of full evaporation of the sprayed water, which is calculated as 50 g/min. Since the injected water cannot evaporate fully in the actual system, the maximum water spray amount is set as 100 g/min. The results showed that the water injection can increase the thermal efficiency up to 95.59% and reduce NOx and CO emissions simultaneously to 8.9 ppm and 35 ppm at 0% of O2. Although the heat energy loss increased due to the unevaporated water, the increase in water injection amount caused higher thermal efficiency due to the increased amount of the evaporated water.
가습연소 폐열회수 보일러의 물분사 설계모델 구축에 관한 연구
신재훈 ( Jaehun Shin ),문석수 ( Seoksu Moon ) 한국분무공학회 2021 한국액체미립화학회지 Vol.26 No.2
In order to improve the overall efficiency and meet the emission regulations of boiler systems, the heat exchanging methods between inlet air and exhaust gas have been used in boiler systems, named as the waste-heat-recovery condensing boiler. Recently, to further improve the overall efficiency and to reduce the NOx emission simultaneously, the concept of the water injection into the inlet air is introduced. This study suggests the models for the optimized design parameters of water injection for waste-heat-recovery condensing boilers and performs the analysis regarding the water injection amount and droplet sizes for the optimized water injection. At first, the required amount of the water injection was estimated based on the 1<sup>st</sup> law of thermodynamics under the assumption of complete evaporation of the injected water. The result showed that the higher the inlet air and exhaust gas temperature into the heat exchanger, the larger the amount of injected water is needed. Then two droplet evaporation models were proposed to analyze the required droplet size of water injection for full evaporation of injected water: one is the evaporation model of droplet in the inlet air and the other is that on the wall of heat exchanger. Based on the results of two models, the maximum allowable droplet sizes of water injection were estimated in various boiler operating conditions with respect to the residence time of the inlet air in the heat exchanger.
75톤 1단 액체로켓엔진 지상시험에서 중앙 물분사가 후류에 미치는 영향 고찰
문윤환(Yoonwan Moon),설우석(Woo-Seok Seol) 한국항공우주연구원 2011 항공우주기술 Vol.10 No.1
본 연구는 중앙 물분사 방식을 채택한 액체로켓엔진 후류의 냉각에 대해 전산유체역학을 통한 특성을 고찰하였다. 중앙 물분사 방식의 냉각은 측면 물분사 방식과는 달리, 잘 알려져 있지 않기 때문에 다양한 물분사량과 유량을 통해 효율적으로 후류를 냉각시킬 수 있는 조건을 찾았으며, 해석을 통해 후류의 변화 특성을 살펴보았다. 이로부터 물분사 유량이 총추진제 유량의 2배 이상, 위치는 L/De=1.2일 때가 적당함을 알 수 있었다. A study of efficient plume cooling by core water injection type was performed by computational fluid dynamics. A side injection type is well known, on the contrary, a core injection type is not well known. In order to figure out the characteristics of core injection type, several calculations were performed by computational fluid dynamics along various mass flow rates and locations of water injection. On the basis of analysis it was the adequate cooling condition that water mass flow rate to total mass flow rate was two times at least and location of water injections was L/De=1.2.
가솔린 기관에서 물 분사 시스템 구성을 위한 시뮬레이션 모델 개발 및 검증
박준혁(Junheuk Park),Maike Sophie Gern 한국자동차공학회 2019 한국자동차공학회 부문종합 학술대회 Vol.2019 No.5
Water spray characterization of a multi-hole water injector is investigated by numerical simulation. Two points of spray characteristics validate spray simulation using CFD. The first validation method is geometrical evaluation involving spray penetration and angles. The second one is conducted concerning heat and mass transfer of water spray, especially for evaporation process of water and resultant cooling effect on air flow. The primary purposes of this study are the development of relevant simulation model and evaluation of the effect of water injection. The ANSYS CFX Software is used to simulate the water spray and gas exchange process of the engine. The 8-hole water injector is applied to water injection, and the spray simulation model for the water injection is developed and calibrated by experimental results.
최윤석(Y.S. Choi),양승용(S.Y. Yang),진성월(S.W. Jin) 한국전산유체공학회 2007 한국전산유체공학회 학술대회논문집 Vol.2007 No.-
An optimized bidet nozzle design to form the required swirl water jet is proposed with the help of numerical analysis. The bidet can do the cleaning process of human body by water injection and the speed/pressure/injection angle/magnitude of swirl intensity of water jet determine the cleaning capability and personal subjective feeling. The objective of this research is to design optimal water injection nozzle to make stable swirl intensity. The effect of individual design variables are analyzed from the basic design and the final design is deduced to make high performance water jet within the pre-determined operation conditions.
최윤석(Y.S. Choi),양승용(S.S. Yang),진성월(S.W. Jin) 한국전산유체공학회 2007 한국전산유체공학회지 Vol.12 No.3
An optimized bidet nozzle design to form the required swirl water jet is proposed with the help of numerical analysis. The bidet can do the cleaning process of human body by water injection and the speed/pressure/injection angle/magnitude of swirl intensity of water jet determine the cleaning capability and personal subjective feeling. The objective of this research is to design optimal water injection nozzle to make stable swirl intensity. The effect of individual design variables are analyzed from the basic design and the final design is deduced to make high performance water jet within the pre-determined operation conditions.
500㎾급 발전기용 LFG엔진에서 물분사에 의한 NOx 저감 특성 연구
박정배(Jeongbae Park),김주일(Jooil Kim),천민우(Minwoo Cheon),이대엽(Daeyup Lee) 한국자동차공학회 2019 한국자동차공학회 학술대회 및 전시회 Vol.2019 No.11
The purpose of this study is to investigate the characteristics of NOx emission reduction by injecting water into the intake port of internal combustion engine for 500㎾ generator using LFG fuel generated from landfill site. Injectors were mounted to each cylinder to control water injecting water into each intake port of 12 cylinder engine. The device was configured to control the start and end of the injection using the cam position signal of the engine so that the injection can be performed only during the intake valve opening period. When the water injection amount was 38 ㎎, the measured NOx reduction was 75%. As a result of measuring and confirming using a rig, it was confirmed that about 90% of the injected water was introduced into the cylinder as a result of measuring the water inflow rate in the combustion chamber. Using the amount of water supplied into the cylinder, it was found that the temperature reduction calculated by the ideal adiabatic condition was about 10 degrees at maximum.
1단용 액체로켓엔진 후류의 측면 물분사 방식 냉각 성능 해석
문윤완(Yoonwan Moon),김승한(Seung-Han Kim),설우석(Woo-Seok Seol) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
In order to investigate cooling performance of side water injection for high temperature plume numerical analyses were performed by using Fluent in accordance with several injected water mass flow rates. In case of the low pressure difference of water injection, cooling effects were slight until water mass flow rate reached three times of total mass flow rate of propellant. In case of the high injected pressure difference of water injection, however, the results were showed that plume was effectively cooled at small water mass flow rate.
물 직접분사를 이용한 PEM 연료전지의 공기극 가습 및 열방출 관한 연구
황성훈(Seong Hoon Hwang),김민수(Min Soo Kim) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
Output power of automotive PEM fuel cell stack is restricted at harsh condition (e.g. high outdoor temperature, high current density, etc.) due to lack of humidification and cooling capacity. In this study direct water injection method is suggested and effects on the humidification and cooling are verified numerically and experimentally. To facilitate water evaporation in the cathode channel of PEMFC, it is very important to atomize liquid water into fine droplets. On the basis of this principle, we selected two-fluid nozzle as an atomization device. This nozzle atomizes liquid water into very fine droplets with high uniformity by air flow momentum. The droplet size becomes smaller as the air-to-liquid ratio increases. It means the droplet diameter decreases with the higher pressure of nozzle air inlet and the smaller liquid flow rate. Water atomizing nozzle was installed as a part of air supply system right before the PEMFC stack. In experiment, compressed air of 1.5 bar was supplied to nozzle and liquid water flow rate was controlled by liquid mass flow controller precisely. 5-cell PEM fuel cell stack of the active area 250 cm<SUP>2</SUP> was used in this study and its performance change under water injection conditions were measured by electronic load.