• 한국자동차공학회논문집
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• 제8권6호
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• pp.60-69
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• 2000

In order to obtain underwater or underground power sources, the closed cycle diesel engine is operated in the non air-breathing circuit system where the major species of the working fluid include oxygen, argon, and recycled exhaust gas. In the present study, the closed cycle diesel engine is designed to operate at the intake pressure between 2 and 3 bar. For operating in the open-cycle and closed-cycle situations, experimental apparatus using this diesel engine is made with ACAP as data acquisition system. In open, semi-open, and closed cycle modes, the predicted p-$\theta$ and P-V are compared with load bank power. Computation have been performed for wide range of major experimental parameters such as the specific fuel and oxygen concentrations, fuel conversion efficiency and polytropic exponent, IMEP and maximum cylinder pressure.

• Journal of Power Electronics
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• 제10권3호
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• pp.235-244
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• 2010

This paper presents a new isolated soft-switching bidirectional buck-boost inverter for fuel cell applications. The buck-boost inverter combines an isolated DC-DC converter with a conventional inverter to implement buck-boost DC-DC and DC-AC conversion. The main switches achieve zero voltage switching and zero current switching by using a novel synchronous switching SVPWM and the volume of the transformer in the forward and fly-back mode is also minimized. This inverter is suitable for wide input voltage applications due to its high efficiency under all conditions. An active clamping circuit reduces the switch's spike voltage and regenerates the energy stored in the leakage inductance of the transformer; therefore, the overall efficiency is improved. This paper presents the operating principle, a theoretical analysis and design guidelines. Simulation and experimental results have validated the characteristics of the buck-boost inverter.

• 대한기계학회논문집B
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• 제30권11호
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• pp.1123-1130
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• 2006

This study discusses about research efforts of hydrogen generation from hydrocarbon(e.g., diesel, gasoline, natural gas, and LPG), especially, butane reforming by using Autothermal Reforming Reaction (ATR) technology. Several catalysts were selected for butane ATR. Thermodynamic reactor conditions (temperature, $O_2$/C, S/C) are varied and reforming characteristics of 2 catalysts (Pt and Rh on ceramic supports) and 1 commercial catalyst (FCR-HC35) have been examined. To understand reaction behaviors in an ATR reactor comprehensively, temperature profiles of reactor were observed. By mass transfer limitation, fuel conversion decreases when GHSV increases. Significant temperature variation along the reactor was observed and it was mainly due reaction kinetics difference between exothermic oxidation and endothermic reforming reaction.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.113-116
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• 2007

Performance of a steam reformer can be improved by using a coaxial cylindrical reactor, because the design can enhance the heat transfer for the steam reforming reaction, which is the one of main rate-determining steps of overall reactions. The objective of this study is to investigate the coaxial cylindrical reactor numerically. Pseudo-homogeneous model and one medium approach are incorporated for the chemical reactions, and models are validated with experimental results. The catalyst of the coaxial cylindrical reactor is 67% for one of the cylindrical reactor, but fuel conversion of the coaxial cylindrical reactor is increased by 10%. Heat flux profiles are investigated by modified Nusselt number and heat flux which is transported from the product gas to the catalyst bed affecting performance of the steam reformer.

• 한국자동차공학회논문집
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• 제9권2호
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• pp.1-10
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• 2001

In order to reduce hydrocarbon emissions of spark ignition engine, it is important not only to improve catalyst conversion efficiency but also to reduce direct engine out hydrocarbon emissions, during cold starting and warm up process. Tjerefore many researchers have been attracted to develop an early fuel evaporator (EFE) by introducing a ceramic heater for a solution of engine out hydrocarbon emissions in SI engine. But, the performance of the EFE in MPI engine to reduce the exhaust emissions and to improve the cold startability has nat been clarified yet. The purpose of this study is to evaluate the feasibility of a glow plug for EFE.

• 한국자동차공학회논문집
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• 제7권5호
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• pp.16-21
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• 1999

The diesel vehicle is relatively superior to gasoline vehicle on the fuel consumption, durability and combustion efficiency. However, exhaust emission from diesel vehicle are known to be harmful to human health and environment. The treatment technologies for the diesel exhaust gases are classified as replacement of fuel, quality control of diesel fuel, improvement of engine and aftertreatment system. The most effective for the treatment technology is known to be aftertreatment system, and this research is continuously conducted by many groups. The DOC system has many advantages of reducing particulates and harmful gaseous substances such as CO. HC. Moreover, it is simple in device structure, relatively low cost, and easy to install witout retrofitting the vehicle. In this study, experiment were conducted to analyze the effects on factors of oxidation characteristics and conversion efficiency of DOC. In experiment, test was conducted to estimate engine emission in 11,000cc diesel engine which was equipped with DOC.

• 한국막학회:학술대회논문집
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• 한국막학회 2003년도 The 4th Korea-Italy Workshop
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• pp.29-32
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• 2003

Polymer electrolyte membranes are developed for the applications to facilitated transport membranes, fuel cells and solar cells. The polymer electrolyte membranes containing silver salt show the remarkably high separation performance for olefin/paraffin mixture in the solid state; the propylene permeance is 45 GPU and the ideal selectivity of propylene/propane is 15,000. For fuel cell membranes, the effects of the presence and size of the proton transport channels on the proton conductivity and methanol permeability were investigated. The cell performance for dye-sensitized solar cells employing polymer electrolytes are measured under light illumination. The overall energy conversion efficiency reaches 5.44 % at 10 ㎽/$\textrm{cm}^2$, to our knowledge the highest value ever reported in the polymer electrolytes.

• 세라미스트
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• 제23권2호
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• pp.132-144
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• 2020

Solid oxide fuel cell (SOFC) have attracted much attention due to clean, efficient and environmental-friendly generation of electricity for next-generation energy conversion devices. Recently, many studies have been reported on improving the performance of SOFC electrodes and electrolytes by applying atomic layer deposition (ALD) process, which has advantages of excellent film quality and conformality, and precise control of film thickness by utilizing its unique self-limiting surface reaction. ALD process with these advantages has been shown to provide functional ceramic interfaces for SOFC electrodes and electrolytes. In this article, recent examples of successful functionalization and stabilization on SOFC electrodes and electrolytes by the application of ALD process for realizing high performance SOFC cells are reported.

• Journal of Power Electronics
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• 제19권5호
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• pp.1278-1288
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• 2019

A DC-DC Non-Isolated Three-Port Cuk-Cuk (NI-TPCC) converter for interfacing renewable energy sources (RESs) such as Fuel Cell (FC) and Photovoltaic (PV) energy with a DC load is presented in this paper. It features single-stage power conversion from both of the input ports to the load port. The proposed NI-TPCC converter is designed based on the classical Cuk converter. The operational modes and power flow are analyzed in the continuous conduction mode (CCM), and the relationships among the port voltages are derived. Continuous currents in all three ports with less ripple enhance the performance of a fuel cell and its operating life. Furthermore, the output inductor is shared with both of the input ports, which reduces the number of active and passive components. The effectiveness of the designed NI-TPCC converter has been validated through simulation and experimental results.

• 공업화학
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• 제34권2호
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• pp.99-105
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• 2023

Recently, 2D materials greatly impact in the various applications especially in the energy conversion and storage devices. Among the 2D materials, nowadays researchers are showing their propensity towards the MXenes due to their potential structural and physical properties as well as their use in various applications. Recently, MXenes have been used as filler in polymer electrolytes membranes and as catalytic support to increase the performance of fuel cells (FCs). But this review covers only recent progress and application of MXenes in proton and anion exchange membranes for FCs. Also, this review will provide a significant guidance and broad overview for future research in MXenes based polymer electrolyte membrane for FCs.