• Title/Summary/Keyword: Secondary Air System

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Heat Transfer and Pressure Drop Characteristics of Secondary Refrigerants Applying to Indirect Refrigeration System (간접 냉동 시스템용 2차 냉매의 열전달과 압력강하 특성)

  • Oh, Hoo-Kyu;Son, Chang-Hyo;Jo, Hwan;Yi, Wen-Bin;Jeon, Min-Ju
    • Journal of Power System Engineering
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    • v.17 no.4
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    • pp.45-50
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    • 2013
  • This paper presents the comparison of heat transfer and pressure drop of various secondary refrigerants (single-phase and two-phase) in the indirect refrigeration system. The main results were summarized as follows: In case of heat transfer, it is useful to use secondary refrigerants in low evaporating temperature region and the heat transfer coefficient of single-phase is larger than two-phase secondary refrigerants. In case of pressure drop, it is useful to use secondary refrigerants in high evaporating temperature region and the pressure drop of two-phase is smaller than single-phase secondary refrigerant. Also, $CO_2$ is the best useful because pressure drop of $CO_2$ among the secondary refrigerants is the smallest.

Analysis of the Gas Flow Field of Primary Combustion Chamber with the Conditions of Secondary Air Injection (2차 공기 주입 조건 변화에 따른 소형 소각로 내부의 유동장 분석)

  • Choi, Byung-Dae;Kim, Sung-Joon
    • Journal of Industrial Technology
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    • v.22 no.A
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    • pp.9-17
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    • 2002
  • This analysis is aimed to find out how the conditions of secondary air injection affects the residence time and the turbulence energy of flue gas and flow field in a small incinerator. A commercial code, PHOENICS, is used to simulate the flow field of an Incinerator. The computational grid system is constructed in a cartesian coordinate system In this numerical experiment, an independent numerical variable is the conditions of secondary air injection and dependants are the residence time of flue gas and the mean value of turbulence energy in a primary combustion chamber. The flow field and the distribution of turbulence energy are analysed to evaluate the residence time of flue gas and the turbulence energy The computational results say that the tangential injection of secondary air make the residence time much longer than the radial injection and that the radial injection of secondary make turbulence much stronger than the tangential injection.

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Heat Transfer and Pump Consumption Power of Indirect Refrigeration System Using CO2 as a Secondary Refrigerant (2차 냉매로서 CO2를 사용하는 간접 냉동시스템의 열전달과 펌프 소비동력)

  • Yoon, Jung-In;Choi, Kwang-Hwan;Son, Chang-Hyo;Yi, Wen-Bin
    • Journal of Power System Engineering
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    • v.18 no.2
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    • pp.25-30
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    • 2014
  • In this paper, the heat transfer coefficient and pump consumption power of indirect refrigeration system using $CO_2$ as a secondary refrigerant were investigated experimentally. First, from the comparison of pump consumption powers of existing brines(EG, PG, EA etc.) and $CO_2$ as secondary refrigerants at the same experimental conditions, PG and $CO_2$ show the highest and lowest power, respectively. Second, the heat transfer coefficient of $CaCl_2$ is the highest, but PG is the lowest among other secondary refrigerants. From the above results, it is confirmed that $CO_2$ as the secondary refrigerant has excellent characteristics when comparing to existing brines. Thus, it is concluded that $CO_2$ is applicable as the secondary refrigerant of indirect refrigeration system.

Performance Characteristics of Refrigeration System Using R744 as a Secondary Refrigerant (2차 냉매로 천연냉매 R744를 사용하는 냉동시스템의 성능 특성)

  • Yi, Wen-Bin;Jo, Hwan;Yoon, Jung-In;Choi, In-Soo;Son, Chang-Hyo
    • Journal of Power System Engineering
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    • v.18 no.4
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    • pp.17-22
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    • 2014
  • In this paper, the performance characteristics of R404 indirect refrigeration system using R744 as a secondary refrigerant were investigated experimentally to obtain a optimum design data for this system. First, for the constant experimental conditions, the COP of R404A indirect refrigeration system using R744 as secondary refrigerants decreases with respect to the increases in R404A condensation temperature and temperature difference in R744 cooler. And, the COP of indirect refrigeration system using R744 as secondary refrigerants decreases slightly with decreasing the mass flowrate of R744.

Experimental Study of the Effect of Secondary Air Injection on the Cold Start Total Hydrocarbon Emissions in a Spark Ignition Engine (스파크 점화기관에서 이차 공기 분사가 냉시동시 THC 배출량에 미치는 영향에 관한 실험적 연구)

  • 이승재;함윤영;전광민
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.1
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    • pp.1-6
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    • 2003
  • Engine emission regulations are becoming more stringent nowadays. In cold transient regime, about 80% THC is exhausted to the atmosphere in the first 200s (US FTP cycles). Accordingly, reducing emission levels in the cold period immediately after the engine start before the catalysts reach their working temperature will be an especially critical factor in meeting more stringent regulations in the future. In this study, the total hydrocarbon quantities are measured using a Fast FID with gasoline fuel for a 4-cylinde. Sl engine, including Secondary Air Injection (SAI) system. Commercial SAI device's direction is reverse to the exhaust flow. In this study, a swirl flow type SAI system which is positioned between the exhaust manifold and exhaust port, was developed. We compared the swirl type secondary air injection with a commercial secondary air injection of .everse flow. The swirl type SAI showed better results in reducing HC by 26% than the commercial flow type SAI of reverse flow which was caused by the better mixing between the exhaust gas and the secondary air.

Numerical Analysis for the Performance Prediction of Combustion Chamber of Commercial Incinerator (상업용 소각로 연소실 성능예측을 위한 수치해석 연구)

  • Lee, Jin-Wook;Park, Byung-Soo;Yun, Yong-Seung;Seo, Jung-Dae;Huh, Il-Sang
    • Journal of the Korean Society of Combustion
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    • v.4 no.1
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    • pp.141-153
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    • 1999
  • Numerical analysis for the combustion flow in the combustion chamber of incineration system has been carried out in order to acquire the basic design capability of incineration system. Established mathematical model was applied to the performance prediction of the pre-designed combustion chamber of commercial plant. Especially, combustion characteristics and the variation of flow pattern have been deeply discussed in accordance with secondary air injection. Secondary air injection was effective for the turbulent mixing between air and carbon monoxide/volatile matter resulting in considerably reduced CO content at the exit. Secondary air injection was found to be one of the key design parameters because the size of recirculation zone could be changed with the variation of injection characteristics.

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Emission Analysis in Catalytic Converter Adopted Secondary Air Injection System for Cold Start Period (2차 공기 공급 시스템을 채택한 촉매 변환기 내 냉 시동 구간 배기가스 해석)

  • Yun, Jeong-Eui
    • Transactions of the Korean Society of Automotive Engineers
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    • v.18 no.6
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    • pp.46-52
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    • 2010
  • In this paper, emission analysis during cold start period of CVS-75 mode in LPG vehicle was performed to find out proper operating conditions of SAI(Secondary Air Injection) system. In order to meet SULEV target, the simulated emission system had a SAI system as well as a MCC(Manifold Catalytic Converter) and a UCC(Under body Catalytic Converter). Using commercial 1-D code AMESIM, in which 7 step global surface chemical reactions of Langmuir-Hinshelwood type were adopted, transient emission analysis in the exhaust system during cold start period of CVS-75 mode were carried out to figure out the effects of flow rate, duration of supply air on HC, CO, NO emission.

Effects of the angle of secondary air inlet on the uniformity of temperature distribution inside an incinerator (2차 공기 주입각이 소각로 내부의 온도 분포 균일도에 미치는 영향)

  • Kim S. J.;Min I. H.;Park M. H.;Park M. J.
    • Journal of computational fluids engineering
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    • v.5 no.3
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    • pp.8-15
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    • 2000
  • This research is aimed to find out how the inlet angle of secondary air affects the uniformity of temperature distribution inside a small incinerator. A commercial code, PHOENICS, is used to simulate the thermal-flow field of an incinerator. The computational grid system is constructed by Multi-Block technique provided by PHOENICS. Numerical experiments are done with the five different angles of secondary air inlet. The uniformity of temperature distribution is evaluated by checking the standard deviation of temperature distribution in an incinerator. The computational results show that there is the minimum value of standard deviation at the certain angle of secondary air inlet, which means that there is an optimum angle of secondary air inlet that could improve the uniformity of temperature distribution in an incinerator. The optimum angle of secondary air inlet is between 30 degree and 45 degree in this particular case.

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Experimental Study on Thermal NOx and CO Emission in a Laboratory-Scale Incinerator with Reversed Secondary Air Jet Injection (역방향 2차 공기 주입 방식을 적용한 소각 연소로의 Thermal NOx 및 CO 배출특성에 대한 축소모형실험 연구)

  • Choi, Chonggun;Choi, Woosung;Shin, Donghoon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.40 no.8
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    • pp.503-510
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    • 2016
  • Incinerators generally emit pollutants such as NOx and CO during the combustion process. In this paper, pollutant emissions and temperature distributions were studied in a simulated incinerator with a reversed (relative to the flue gas flow) secondary air injection system. The experiments were performed by using a lab-scale furnace in order to evaluate the effects of the injection location, direction and flow rate of secondary air jets. The emission of NOx was lower in the case of reversed secondary air injection than in the case of cross injection, due to the recirculation and mixing of the exhaust gas. In the reversed air injection cases, thermal NOx emissions decreased as secondary air ratio increased from 30 to 60 and slightly increased at secondary air ratios higher than 60. In most cases, CO emissions were not detected except for a few reversed secondary air injection cases, in which cases CO concentrations below 2ppm were observed.

CFD Analysis on the Fresh Air Distribution in the Catalytic Converter Varying Secondary Air Injector Position (2차 공기 분사 위치에 따른 촉매 내 공급 공기 분포에 대한 전산 유동해석)

  • Yun, Jeong-Eui
    • Transactions of the Korean Society of Automotive Engineers
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    • v.18 no.5
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    • pp.31-36
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    • 2010
  • SAI(Secondary Air Injection) system has been studied widely as one of the promising countermeasure for reducing HC emission at cold start. In this paper, in order to find out the optimal position of SAI, computational thermal fluid analysis on exhaust system adapted SAI system is performed using commercial 3-D CFD code, CFX. The present results showed that SAI position strongly affected the uniformity of air distribution in front of catalyst. And also through the decision process of optimal position of SAI, new index, uniformity of air distribution($U_{\phi}$) is proposed to define it quantitively. Because $U_{\phi}$ is very simple equation and similar with flow uniformity, it is very easy to figure out the physical meaning and to apply it to practices. Finally, we applied the index $U_{\phi}$ to the decision process of the optimal position of SAI, so that we could get the clear comparison results.