• Transactions of the Korean hydrogen and new energy society
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• v.30 no.2
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• pp.163-169
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• 2019

This study is a research to compare efficiency of new cooling system (chiller, pre-cooler) to that of the conventional system at the hydrogen refueling station (HRS). This study includes contents for thermodynamic comparison of cooling system for HRS and comparison of pros and cons of its components. So It is to establish design concept of cooling system of HRS supplying with fuel cell electric vehicle (FCEV). HRS is charging high pressure H2 (700 bar) to FCEV. However cooling system is need to prevent temperature rise in tank. This cooling system consists of pre-cooler and chiller system.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.65-68
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• 2013

In a syngas cooling system of coal gasification process, fly slag carried by syngas deposit on the surface of heat exchanger. The deposited materials form a fouling layer with several millimeters thickness, disturbing heat transfer between steam and syngas. This study investigates flow and heat transfer characteristics of syngas in helical coil heat exchanger using computational fluid dynamics under clean and fouled surface condition. Process model were also designed and its results are in good agreement with CFD results.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.225-226
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• 2003

최근 인간의 생활환경에 존재하는 유해가스 및 대기 환경에 대한 관심이 고조되면서 환경유해가스를 손쉽게 감지할 수 있는 센서의 필요성이 중요하게 인식되고 있다. 그 중 암모니아 가스는 생활환경 내에 존재하는 악취성분일 뿐만 아니라 냉각기의 냉매로 사용되는 가스로서 대기 중 허용농도가 50 ppm으로 알려져 있다. 본 연구에서는 프린트스크린 인쇄법을 이용하여 SnO$_2$를 모물질로 하여 귀금속 산화물인 Pt와 Au를 첨가한 암모니아 반도체 가스센서를 제조하여 그 감도 및 SO$_2$, NOx, CH$_4$, NH$_3$, 에 대한 선택성을 분석하였다. (중략)

• Journal of the korean Society of Automotive Engineers
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• v.6 no.1
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• pp.11-20
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• 1984

이글에서는 메타놀의 성상과 재래의 내연기관에 메타놀을 사용하였을 때의 특성을 몇 가지 관 점에서 살펴보았다. 유리한 점으로 판단되는 사실은, 1)옥탄가가 높아 고압축비의채용으로 열 효율을 높일 수 있다. 2)기화참열이 크고 물과의 친화성이 좋다. 이러한 점은 내부냉각방식의 채용으로 이상적인 충상혼합기를 형성할 수가 있을 것이며, 현재의 내연기관의 냉각계통, 즉 방 열기, 물펌프, 냉각휜 등을 줄일 수 있을 것으로 본다. 또 NO.chi.의 배출을 저하시키는 이점도 있다. 3)단일성분 연료이므로 배기가스 조성이 단순하며 깨끗하다. 이는 배기공해상 메타놀연료가 석유계연료보다 유리하다. 그러나 메타놀기관은 앞으로 기술적 연구, 개선을 필요로 하는 점도 있다. 1) 메타놀의 가솔린과 비교하여 인화점이 높고 기화잠열이 커서 시동성이 나쁘고 2) 메타놀은 어느 종류의 금속, 프라스택, 도료 등을 부식시킨다. 3) 메타놀은 세탄가가 낮아, 압축점화는 무리이며 4) 발열량은 석유계 연료의 약 절반이다. 따라서 시동성, 재료, 착화방법, 개질 가스의 이용법, 내부냉각 등의 기술적인 문제가 개발된다면 질, 량, 가격적인 면에서도 내연기관용에는 메타놀이 유리하다고 본다. 그러나 현시점에서는 기관측으로 보아 자동차용연료로는 가솔린에 혼합하는 방법이고 그렇게 된다면 20-30%의 연료가 절감되리라고 믿는다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.763-764
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• 2012

• Journal of the Korean Society of Propulsion Engineers
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• v.6 no.4
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• pp.1-6
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• 2002

A numerical heat transfer analysis and the structural analysis were performed for the design of sub-scale combustion chamber's coolant passage. The heat flux through the combustion chamber wall was estimated by 2-D heat transfer analysis of compressible hot gas and the result was applied as a thermal boundary condition of 3-D analysis. The heat flux estimated by the present method agreed well with the experimental correlation and proved to be insensitive to cooling condition. So the same thermal boundary condition was applied for various operating conditions. The maximum temperature of combustion chamber wall was predicted by 3-D analysis for single coolant passage and the result will be used for the development of a regeneratively cooled combustion chamber. Also estimated were the stress distribution and structural safety of coolant passage through the static structural analysis.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.43 no.8
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• pp.52-57
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• 2014

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.961-966
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• 2009

This paper presents precise temperature control of oil outlet in an oil cooler with hot-gas bypass control as an industrial refrigerator. The control system was designed for obtaining precise temperature control performance even though abrupt disturbances based on flow rate control of hot-gas bypass. PID controller was adopted in feedback control system. We showed that the gain of PID could be easily determined by using gain-tuning methods without any numerical model. Through some experiments, excellent control performances such as overshoot within 1.7%, steady state temperature error within ${\pm}0.1^{\circ}C$ were established by a simple PI controller. We expect that the system can control the target temperature within error of $0.33^{\circ}C$ under abrupt disturbances.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.9
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• pp.1238-1247
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• 2003

Simplified thermodynamic analysis of high pressure 4-stage reciprocating compressors with 4 inter-coolers has been investigated to predict a behavior of a compressor system for NGV(natural gas vehicles). A computer program has been developed to predict and estimate the performance of high pressure 4-stage reciprocating compressor system. Thermodynamic properties of compressed natural gas(CNG) were calculated by ideal gas theory and compression cycle was assumed as reversible adiabatic compression and expansion processes, and isobaric intake and discharge processes. Comparison between results predicted by calculation model and measured by experimental tests is presented.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.3
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• pp.97-103
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• 2012

The combustion chamber and nozzle of a liquid rocket engine should be protected from the high temperature combustion gas generated by the chamber. An upper-stage nozzle extension has a large expansion ratio, therefore, The light-weight refractory materials have been used since the weight impact on the launcher performance is crucial. Gas film cooling method was used before, but was not applicable nowadays. Ablative cooling method and radiative cooling method with niobium alloy, Ni-based superalloy and ceramic based composite have been used to this day.