KS C 8569 기반의 연료전지시스템 성능평가 및 그 운영에 관한 고찰

차정은(Jung-Eun Cha),이남진(Nam Jin Lee),최영우(Young-Woo Choi),윤영기(Young Ki Yoon),김원배(Won Bae Kim) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4

연료전지는 수소와 산소로부터 전기화학 반응을 통해 직접 전기를 생산하는 발전장치로, 연료전지 시스템은 연료전지 스택, 연료변환기, 주변기기(MBOP: Mechanical Balance of Plant, EBOP: Electrical Balance of Plant) 및 제어기술을 포함한다. 연료전지 보급이 확대되면서, 안전과 성능 검증을 위한 표준이 요구되었으며, 이에 따라 표준서 KS C 8569는 2015 년 고분자연료전지(PEMFC) 시스템에 대하여 KS 제정을 시작으로 2019 년에는 직접 메탄올 연료전지(DMFC)시스템을, 2020 년에는 고체고분자연료전지(SOFC)시스템을 포함함으로써 현재의 표준서가 완성되었다. KS C 8569는 발전효율, 열효율, 기동/정지 특성, 부하변동 등을 포함하는 성능평가와 온도상승, 절연, 계통 보호, 내전기환경시험 등의 안정성 평가, 그리고 배출가스, 소음측정 등 환경성 평가로 구분되며, 총 49 개 상세항목으로 구성되어 있다. 초반 4 개 기업의 정지형, 즉 건물용 PEMFC 연료전지시스템의 KS 인증을 시작으로 현재 SOFC까지 포함하여 13 여개 기업으로 확장되었다. 또한, 초반에 1 kW 급 이하의 시스템이 대부분이었으나 2017 년 이후부터는 5 kW이상, 최근에는 10 kW 시스템이 주력을 이루고 있다. 하지만, 지금의 표준서는 기존의 정지형에서 이동형을 결합한 것으로 평가내용이 혼재되고, 이동형의 기본성능 (직류), 내열, 충격, 진동, 냉온 등의 안전성 검사 기준이 미흡하다. 또한, 정지형의 경우 10kW 급 이하로 규정되어 있어서 100 kW 이하의 과도기적인 시장 제품에 적합하지 못하다. 따라서, KS C 8569를 재정비하고, 국제표준과의 부합화를 통하여 국내 연료전지 산업 육성과 더불어 수출전략 고도화 가능성을 모색해야한다. The fuel cell is one of the power generating systems converting the chemical energy of hydrogen and oxygen into electricity through a pair of redox reactions, which mainly consists of a fuel reformer, cell stack, and an inverter. With the expansion of the supply of fuel cell systems, test standards and certifications have been required to verify the safety and performance of fuel cells. Starting with KS certification for polymer electrolyte membrane fuel cell (PEMFC) systems in 2015, KS C 8569 has been completed by including direct methanol fuel cell (DMFC) systems in 2019 and solid oxide fuel cell (SOFC) systems in 2020. This certification is divided into the performance assessment including power generation efficiency, thermal efficiency, start-up/shut-down characteristics, stability evaluation for the increase in temperature, electric resistance test, and the environmental assessment such as emissions and noise measurements. Initially, four fuel cell system manufacturers obtained KS certification for the stationary system, and now it has been expanded to a total of 13 companies including SOFC and DMFC system manufacturing companies. Besides, most of the systems were 1 kW or lower in the beginning, however since 2017, the capacity has increased to 5 kW or higher, and 10 kW systems have recently become the main focus. However, this standard has been revised to add the mobile fuel cell system standard to the existing stationary fuel cell standard, which lacks basic performance (direct current), heat resistance, shock, vibration, cold and hot tests that conform to the mobile fuel cell system standard. In addition, stationary fuel cell systems are not suitable for transition market products under 100 kW because they are defined as less than 10 kW. Accordingly, KS C 8569 should be reviewed to suit international standards and transitional market products to promote the domestic fuel cell industry and seek the possibility of upgrading its export strategy.

작동 조건 변화에 따른 직접 메탄올 연료전지의 성능 특성

서상헌(Sang Hem Seo),이도연(Do Youn Lee),이창식(Chang Sik Lee) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

In this work, the characteristics of a direct methanol fuel cell (DMFC) were investigated under changes of various operating conditions in order to understand the behaviors of the single fuel cell and find the optimal operating conditions. The operating parameters included the operating temperature. methanol concentration, flow rate, cathode humidification temperature, and so on. The membrane electrode assembly(MEA), with a Pt-Ru(4㎎/㎠) anode catalyst and Pt-black(4㎎/㎠) cathode catalyst, was used for methanol oxidation and oxygen reduction. The methanol in water solution was used as the fuel and the air was used as the oxidant in all experiments. The cell performance was analyzed based on the measurement of the current-voltage and current-power density characteristics expressed by polarization curve. The results showed that performance of the single cell was enhanced by increasing cell temperature, air flow rate, cathode back-pressure. but the temperature effect of cathode preheater was almost negligible. When cathode backpressure was increased up to 200kPa, the highest single cell power density of 0.178W/㎠ was achieved with 1M methanol feed at 80°C of cell temperature. From this experimental study, it was revealed that changing various conditions can be an important role in suitable operation of DMFC.

Sensor-less control of methanol concentration based on estimation of methanol consumption rates for direct methanol fuel cell systems

Ha, T.J.,Kim, J.H.,Joh, H.I.,Kim, S.K.,Moon, G.Y.,Lim, T.H.,Han, C.,Ha, H.Y. Pergamon Press ; Elsevier Science Ltd 2008 International journal of hydrogen energy Vol.33 No.23

Adequate control over the concentration of methanol is critically needed in operating direct methanol fuel cell (DMFC) systems, because performance and energy efficiency of the systems are primarily dependent on the concentration of methanol feed. For this purpose, we have built a sensor-less control logic that can operate based on the estimation of the rates of methanol consumption in a DMFC. The rates of methanol consumption are measured in a cell and the resulting data are fed as an input to the control program to calculate the amount of methanol required to maintain the concentration of methanol at a set value under the given operating conditions of a cell. The sensor-less control has been applied to a DMFC system employed with a large-size single cell and the concentration of methanol is found to be controlled stably to target concentrations even though there are some deviations from the target values.

Direct Methanol Fuel Cells

McGrath, Kimberly M.,Prakash, G. K.Surya,Olah, George. A. 한국공업화학회 2004 Journal of Industrial and Engineering Chemistry Vol.10 No.7

Over the past 15 years, the electrical performance of direct methanol fuel cells (DMFCs) has increased at least tenfold. With this advancement, portable DMFC-powered devices have come to fruition along with dramatic improvement in small power plant and transportation applications. While the DMFC has a theoretical energy density of 6094 W h/kg, only 1000-3200 W h/kg of this energy is realized in practice. Although most portable power applications only necessitate several W h/kg, performance and cost issues associated with polymer electrolyte membranes (PEMs), anode and cathode catalysts, system design, and operational considerations must be overcome for DMFCs to have a role in the methanol economy. This review covers mostly the chemistry aspects of DMFCs.

전해질 두께가 직접 메탄올 연료전지의 성능에 미치는 영향

서상헌(Sang Hern Seo),이창식(Chang Sik Lee) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

The purpose of this work is to investigate the effect of membrane thickness on the performance of direct methanol fuel cell(DMFC) at various operating conditions. The membranes of Nafion 115(127㎛) and Nation 212(50.8㎛) were examined with changes of operating temperature, concentration of methanol solution, flow rate and cathode backpressure. The experiments were performed by using 5㎠ single cell with serpentine flow field for both anode and cathode. The catalyst loading on the anode was 4㎎/㎠ with Platinum-Ruthenium and the catalyst loading on the cathode was 4㎎/㎠ Platinum-Black. The performance was expressed by voltage-current density curve. It was found that the performance of DMFC was improved by decreasing of resistance with increase of membrane thickness. whereas the open circuit voltage(OCV) was increased by reducing of methanol crossover. Therefore. thc optimal membrane thickness can be an important factor to operate maximum performance in DMFC.

A prediction model of degradation rate for membrane electrode assemblies in direct methanol fuel cells

Bae, S.J.,Kim, S.J.,Um, S.,Park, J.Y.,Lee, J.H.,Cho, H. Pergamon Press ; Elsevier Science Ltd 2009 International journal of hydrogen energy Vol.34 No.14

This article proposes a new prediction model to describe the nonlinear performance degradation paths of membrane electrode assemblies (MEAs) in direct methanol fuel cell (DMFC): a bi-exponential model with random coefficients. The bi-exponential model is constructed on a mathematical basis representing second-order kinetics. Performance variation between MEAs is incorporated by random coefficients in the proposed model. A likelihood ratio test is sequentially executed to select random effects in the nonlinear random-coefficients model. Analysis results indicate that the reliability estimation can be substantially improved by using the nonlinear random-coefficients model to incorporate two heterogeneous degradation characteristics of MEA performance during continuous operation of DMFC. Confidence intervals of failure-time distributions are obtained by the parametric bootstrap method.

방사선 그라프트 PFA-폴리스티렌 멤브레인으로 제조한 직접 메탄올 연료전지용 MEA의 성능과 특성

강세구,백동현,김상경,임성엽,정두환,박영철,신준화,강필현,노영창,설용건,Kang, Se-Goo,Peck, Dong-Hyun,Kim, Sang-Kyung,Lim, Seong-Yop,Jung, Doo-Hwan,Park, Young-Chul,Shin, Jun-Hwa,Kang, Phil-Hyun,Nho, Young-Chang,Shul, Yong-Gun 한국전기화학회 2009 한국전기화학회지 Vol.12 No.2

DMFC (Direct Methanol Fuel Cell)용의 새로운 고분자 전해질 멤브레인을 개발하기 위하여 스티렌 단량체를 poly(tetrafluoroethylene perfluoropropyl vinyl ether) (PFA) 필름에 그라프트 중합 반응시킨 후에 술폰화 반응을 진행하였다. $\Upsilon$-ray를 이용하여 방사선 그라프트 중합 반응시킨 방사선 그라프트 필름의 술폰화 반응은 chlorosulfonic acid/dichloroethane (5 v/v%) 혼합 용액에서 진행하였다. PFA 그라프트 폴리스티렌 멤브레인 (PFA-g-PSSA)의 화학적, 물리적, 전기화학적 및 형태의 특성은 푸리에 변환 적외선 분광기 (FTIR), 이온전도도 측정기 및 주사전자현미경 (SEM)으로 분석하고 함수율과 메탄올 투과도도 측정하였다. PFA-g-PSSA 멤브레인으로 제작한 MEA의 단위전지 성능을 평가하였고, 전지의 셀 저항은 임피던스 분석 장치를 이용하여 측정하였다. PFA-g-PSSA 멤브레인으로 제조한 MEA는 Nafion 112로 제조한 MEA보다 우수한 DMFC 성능을 나타내었다. In order to develop a novel polymer electrolyte membrane for direct methanol fuel cell (DMFC), styrene monomer was graft-polymerized into poly(tetrafluoroethylene perfluoropropyl vinyl ether) (PFA) film followed by a sulfonation reaction. The graft polymerization was prepared by the $\Upsilon$-ray radiation-grafting method. Subsequently, sulfonation of the radiation-grafted film was carried out in a chlorosulfonic acid/1,2-dichloroethane (2 v/v%) solution. The chemical, physical, electrochemical and morphological properties of the radiation-grafted membranes (PFA-g-PSSA) were characterized by fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The water uptake, ionic conductivity, and methanol permeability of the PFA-g-PSSA membrane were also measured. The cell performances of MEA prepared with the PFA-g-PSSA membranes were evaluated and the cell resistances were measured by an impedance analyzer. The MEA using PFA-g-PSSA membranes showed superior performance for DMFCs in comparison with the commercial Nafion 112 membrane.

A study on the overall efficiency of direct methanol fuel cell by methanol crossover current

Seo, Sang Hern,Lee, Chang Sik Elsevier 2010 APPLIED ENERGY Vol.87 No.8

<P><B>Abstract</B></P><P>This paper was presented to determine the methanol crossover and efficiency of a direct methanol fuel cell (DMFC) under various operating conditions such as cell temperature, methanol concentration, methanol flow rate, cathode flow rate, and cathode backpressure. The methanol crossover measurements were performed by measuring crossover current density at an open circuit using humidified nitrogen instead of air at the cathode and applied voltage with a power supply. The membrane electrode assembly (MEA) with an active area of 5cm<SUP>2</SUP> was composed of a Nafion 117 membrane, a Pt–Ru (4mg/cm<SUP>2</SUP>) anode catalyst, and a Pt (4mg/cm<SUP>2</SUP>) cathode catalyst. It was shown that methanol crossover increased by increasing cell temperature, methanol concentration, methanol flow rate, cathode flow rate and decreasing cathode backpressure. Also, it was revealed that the efficiency of the DMFC was closely related with methanol crossover, and significantly improved as the cell temperature and cathode backpressure increased and methanol concentration decreased.</P>

총설 : 수소,연료전지 기술

손재익 ( Son Jae Ig ) 한국화학공학회 2004 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.42 No.1

Among various technologies using hydrogen-energy, fuel cells have been considered as the most energy efficient technology. A conventional combustion-based power plant typically generates electricity at efficiencies of 33 to 35 percent, while fuel cell plants can generate electricity at efficiencies of up to 60 percent. When fuel cells are used to generate electricity and heat(co-generation), they can reach efficiencies of up to 85 percent. Moreover, fuel cells generate virtually zero pollution including greenhouse gases such as CO_(2). Therefore, the fuel cells are believed as a most promising alternative power producing technology, which can solve global problems facing 21st century such as exhaustion of fossil fuels and environmental pollution at the same time. In this review, recent trends in fuel cell R&D are summarized focusing on PEMFC and DMFC which are closest to the practical use and can be used for batteries, electrical power sources for automobiles and immobile structures such as buildings.

무인항공기용 200W 급 직접메탄올연료전지 경량화 스택 제작 및 작동 특성 연구 (II)

강경문,박성현,곽건희,지현진,주현철 한국수소및신에너지학회 2012 한국수소 및 신에너지학회논문집 Vol.23 No.3

A lightweight 200W direct methanol fuel cell (DMFC) stack is designed and fabricated to power a small scale Unmanned Aerial Vehicle (UAV). The DMFC stack consists of 33-cells in which membrane-electrode assemblies (MEAs) having an active area of 88 cm2 are sandwiched with lightweight composite bipolar plates. The total stack weight is around 3.485 kg and stack performance is tested under various methanol feed concentrations. The DMFC stack delivers a maximum power of 248 W at 13.2 V and 71.3℃ under methanol feed concentration of 1.2 M. In addition, the voltage of individual cell in the 33-cell stack is measured at various current levels to ensure the stability of DMFC stack operations. The cell voltage distribution data exhibit the maximum cell voltage deviation of 28 mV at 15 A and hence the uniformity of cell voltages is acceptable. These results clearly demonstrate that DMFC technology becomes a potential candidate for small-scale UAV applications.