• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.7
• /
• pp.693-699
• /
• 2011

Internal combustion engines running on syngas, which can be obtained from biomass or organic wastes, are expected to be one of the suitable alternatives for power generation, because they are environment-friendly and do not contribute to the depletion of fossil fuels. However, syngas has variable compositions and a lower heating value than pure natural gas, owing to which the combustion conditions need to be adjusted in order to achieve stable combustion. In this study, a gas that has the same characteristics as syngas, such as low heating value (LHV), was produced by mixing $N_2$ with compressed natural gas (CNG). In addition, this study investigates the combustion characteristics of syngas when it is mixed with hydrogen in a ratio ranging from 10% to 30% with a constant LHV of total gas.

• Transactions of the Korean hydrogen and new energy society
• /
• v.13 no.4
• /
• pp.304-312
• /
• 2002

In this study, the performance of the $5Nm^3/hr$ compact type steam reformer which was developed for application of fuel cell or hydrogen station was evaluated in terms of gas process efficiency. For these purposes, reforming efficiency and total efficiency with system load change were analyzed. The reforming efficiency was calculated from the total molar flow of hydrogen output over total fuel flow input to the reformer and the burner on the higher heating value(HHV). In the case of the total efficiency, recovered heat at the heat recovery exchanger was considered. From the results, it was known that system performance was stable, because methane conversion showed the a slight decline which is about 2% though increasing system load to full. Reforming efficiency was increased from 20% to 58%, respectively as increasing system load from 10% to 90%. It was found that total efficiency was higher then reforming efficiency because of terms of heat recovered. As a results, it was known that total efficiency was increased form 75% to 83% at the 10% and 90% system load, respectively. From these results, it is concluded that compact steam reformer which is composed of stacking plate-type reactors is suitable to on-site hydrogen generator or to fuel cell application because of quick start within 1 hr and good performance.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.20 no.3
• /
• pp.257-262
• /
• 2011

A low capacity generator converted to high capacity of 40m3 is designed and developed in order to use the hydroxy gas in the steel manufacturing process. For efficient design, it is increased from 8 electrode tubes to 10 electrode tubes as well as expanding the diameter of cell integument up to two times bigger, which can increase the amount of hydrogen occurrence per a cell significantly. In addition, circulating pump and pipe, heat exchanger of affiliated SUS material have been used in the circulation of electrolysis catalyst, and circulating cooling section and piping design are also developed. The flame trap is designed into all-in-one suitable check valve in the flow rate of 28-35m3/h and its application is possibly applied in work operation. It is found that the efficiency of generator developed is enhanced substantially up to 84%. It is expected that the application in this field can be expanded significantly by this study.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.06a
• /
• pp.226.2-226.2
• /
• 2010

수소경제로 가는 길목에서의 압축천연가스에 수소를 첨가한 수소-압축천연가스(HCNG)는 자동차 연료로서의 뛰어난 효과로 인해 미국, 캐나다, 유럽 등에서는 강화되고 있는 자동차의 배출가스 규제에 대해 만족할 수 있는 차세대 천연가스 자동차의 대안으로서 관련 기술개발과 실증사업에 주력하고 있다. 향후 수소시대의 도래에 즈음하여 HCNG의 사용은 수소사용에 대한 인식 향상과 아울러 수소사용을 안정적으로 공급할 수 있는 토대를 마련하고 수소제조 등 여러 분야에서 기술개발을 할 수 있는 부가적인 효과가 있다고 하겠다. 따라서 최근 국내에서 시내버스와 청소차등에서 천연가스 차량의 보급이 확대되고 있고, 충전소도 점차 확대되고 있는 상황에서 HCNG 연료의 적용가능성을 확인하기 위한 연구가 진행되고 있다. 본 논문에서는 선진국과 국내의 기술개발 현황을 소개하고 향후 우리에게 필요한 과제가 무엇인지를 생각해보는 기회를 갖고자 하였다.

• New & Renewable Energy
• /
• v.6 no.3
• /
• pp.30-38
• /
• 2010

수소경제로 가는 길목에서의 압축천연가스에 수소를 첨가한 수소-압축천연가스(HCNG)는 자동차 연료로서의 뛰어난 효과로 인해 미국, 캐나다, 유럽 등에서는 강화되고 있는 자동차의 배출가스 규제에 대해 만족할 수 있는 차세대 천연가스 자동차의 대안으로서 관련 기술개발과 실증사업에 주력하고 있다. 향후 수소시대의 도래에 즈음하여 HCNG의 사용은 수소사용에 대한 인식 향상과 아울러 수소사용을 안정적으로 공급할 수 있는 토대를 마련하고 수소제조 등 여러 분야에서 기술개발을 할 수 있는 부가적인 효과가 있다고 하겠다. 따라서 최근 국내에서 시내버스와 청소차등에서 천연가스 차량의 보급이 확대되고, 충전소도 점차 확대되고 있는 상황에서 HCNG 연료의 적용가능성을 확인하기 위한 연구가 진행되고 있다. 본 논문에서는 인프라 관점에서의 선진국과 국내의 기술개발 현황을 소개하고 향후 우리에게 필요한 과제가 무엇인지를 생각해보는 기회를 갖고자 하였다.

• Journal of the Korean Ceramic Society
• /
• v.26 no.3
• /
• pp.331-340
• /
• 1989

In this study, it was tried to deposit diamond films from a mixture of CH4 and H2 by the microwave plasma chemical vapor deposition(MWCVD). The MWCVD process was designed and set up from the 2.45GHz microwave generator. And the diamond film was successfully deposited on silicon wafers from the mixture of methane and hydrogen. The microstructures of the deposited diamond films were studied by using the following deposition variables : (a) methane concentration(0.6-10%), (b) reaction pressure(10-100torr), and (c) the substrate temperature(450-76$0^{\circ}C$).

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2006.05a
• /
• pp.347-350
• /
• 2006

The rocket grade hydrogen peroxide has been widely used as a monopropellant in propulsion systems. In the present paper, we described an experimental study of a catalytic reactor that employs two stage catalyst beds to enhance the low temperature performance of the reactor. $K_2MnO_4$ was chosen as the catalyst for the initial stage of the reactor bed for its superior behavior in the low temperature regime. LSC was used for the catalyst of the second stage of the reactor. The gas generator with combined catalyst beds was built and tested to exhibit high decomposition efficiency over 90% and successful cold-start characteristics.

• Transactions of the Korean hydrogen and new energy society
• /
• v.27 no.1
• /
• pp.114-120
• /
• 2016

This paper describes generating efficiency characteristics of the double acting Stirling engine/generator for domestic small-scale CHP (Combined Heat and Power) system. In small distributed generation applications, Stirling engine has competition from fuel cell, microturbine and etc. In order to be economical in the applications, a long life with minimum maintenance is generally required. Free piston Stirling engine (FPSE) has no crank and rotating parts to generate lateral forces and require lubrication. Double acting Stirling engine/generator has one displacer and two power piston which are supported by flexure springs. Two power pistons oscillate with symmetric displacement and are connected with moving magnet type linear generators for power generation from PV work. In experiments, 1 kW class double acting free piston Stirling engine/generator is fabricated and tested. Heat is supplied to hot end of engine by the combustion of natural gas and converted to electric power by linear generators which are assembled with power pistons. The electric parameters such as voltage, current and phase are measured with for variable flow rate of fuel gas. Especially, generating efficiency of FPSE is measured with three different measurement methods. Generating efficiency of the double acting Stirling engine/alternator is about 24%.

• Transactions of the Korean hydrogen and new energy society
• /
• v.26 no.6
• /
• pp.638-644
• /
• 2015

This paper describes the continuing effort to analysis and design on dynamic and electrical behavior of gamma-type free piston Stirling engine/generator with dual-opposed linear generator for domestic micro-CHP (Combined Heat and Power) system. The double acting Stirling engine/generator has one displacer and two power piston which are supported by flexure springs. Two power pistons oscillate with symmetric sinusoidal displacement and are connected with moving magnet type linear generators for power generation. To operate Stirling engine/generator, combustion heat of natural gas is supplied to hot-end and heat is rejected from cold-end by cooling water. The temperature difference across the displacer induces the oscillating motion, and it can be explained with mass-spring vibration system. The purpose of this paper is to describe the design process of linear generator for the double acting free-piston Stirling engine.

• Transactions of the Korean hydrogen and new energy society
• /
• v.29 no.1
• /
• pp.11-18
• /
• 2018

A high efficiency integrated reforming system for improving the efficiency of the 5 kW PEMFC system used as the back up power of building was studied. The separated reforming system consisted of three parts - A steam reformer with two stage concentric circular shape, a heat exchanger type steam generator and a CO shift reactor. Temperature and steam carbon ratio (SCR) were control variables during operation. The operating conditions were optimized based on the thermal efficiency of the steam reformer as reformate gas composition changes at different temperature. In experiments, water was fully vaporized in the steam generator up to SCR 3.5 and the maximum thermal efficiency was achieved at the operating temperature around $700^{\circ}C$ in the steam reforming reactor. With the results of the separated reforming system research, we improved the shape of high efficiency integrated reformer. The performance evaluation of the integrated reformer was based on optimized operating conditions in SCR 3.5. As a result, the developed integrated reforming system maintained an efficiency of 76% and constant performance over 3,000 hours.