• 한국신재생에너지학회:학술대회논문집
• /
• 2007.11a
• /
• pp.31-34
• /
• 2007

Fuel cell with high electric efficiency has many probabilities of commercial use. Especially, polymer electrolyte or proton exchange membrane fuel cell (PEMFC) which is a low operating temperature and has less influence on $CO_2$ concentration is considered the power generation system of small building and household. We calculated the optimal operational plans of 1 kW household PEMFC power system based on daily electric and heat demand patterns of various size of apartments. Calculated results show that the economic feasibility of PEMFC power system is very sensitive to the cost policy of electricity and natural gas.

• 한국전기화학회:학술대회논문집
• /
• 2004.06a
• /
• pp.37-42
• /
• 2004

To maintain proper operating conditions is important to get optimal output power of a PEMFC stack. The air cooled fuel cell stack is widely used in sub kW PEMFC systems. A 500W air cooled PEMFC stack was experimentally investigated to evaluate the design performance and to get optimal operating conditions for the portable application. The relationship between the operating conditions and the performance was analyzed. The results can be used as design criteria for portable PEMFC under various conditions.

• Membrane Journal
• /
• v.26 no.2
• /
• pp.146-151
• /
• 2016

Sulfonated poly (arylene ether sulfone) (SPAES) random copolymers have merits such as high proton conductivity, relatively low production cost, and thermochemical resistance when applied as polymer electrolyte membranes for fuel cells. However, it is difficult to directly employ SPAES copolymers into practical fuel cell membrane applications owing to their low chemical stability and dimensional instability under harsh operation conditions. A plausible solution is to impregnate SPAES copolymers into support films (e.g., electrospun polyimide support) with interconnected pore structures and high thermochemical toughness. In this study, a SPAES copolymer with a swivel group, which induces high free volume for fast ion transport, is chosen as ionomers to prepare pore-filling membranes (PFMs). The feasibility of the resulting membranes is evaluated via membrane characterizations.

• Membrane Journal
• /
• v.16 no.4
• /
• pp.276-285
• /
• 2006

Acid-doped sulfonated poly(aryl ether benzimidazole) (S-PAEBI) copolymers were synthesized by a direct polymerization technique and a doping with phosphoric acid as a dopant, and the polymer electrolyte membranes were fabricated from them by a solution casting method. To optimize the reaction condition, the degree of sulfonation and doping level were varied in the ranges of $0{\sim}60%\;and\;0.7{\sim}5.7$, respectively. Physiochemical properties of the doped membranes were investigated by AFM, TGA and the measurement of proton conductivity. It was found that proton conductivities depend on doping levels of membranes. Conductivity determined at the condition of $130^{\circ}C$ and no humidity was $7.3{\times}10^{-2}S/cm$ for the $H_3PO_4$-doped PAEBI membrane with a doping level of 5.7.

• Journal of the Korean Society for Precision Engineering
• /
• v.31 no.10
• /
• pp.955-965
• /
• 2014

Transport phenomena of reactant and product are directly linked to intrinsic inhomogeneous random configurations of catalyst layer (CL) that consist of ionomer, carbon-supported catalyst (Pt/C), and pores. Hence, electrochemically active surface area (ECSA) of Pt/C is dominated by geometrical morphology of mass transport path. Undoubtedly these ECSAs are key factor of total fuel cell efficiency. In this study, non-deterministic micro-scale CLs were randomly generated by Monte Carlo method and implemented with the percolation process. To ensure valid inference about Pt/C catalyst utilization, 600 samples were chosen as the number of necessary samples with 95% confidence level. Statistic results of 600 samples generated under particular condition (20vol% Pt/C, 30vol% ionomer, 50vol% pore, and 20nm particle diameter) reveal only 18.2%~81.0% of Pt/C can construct ECSAs with mean value of 53.8%. This study indicates that the catalyst utilization in fuel cell CLs cannot be identical notwithstanding the same design condition.

• Transactions of the Korean hydrogen and new energy society
• /
• v.27 no.1
• /
• pp.36-41
• /
• 2016

The development need of new renewable energy is more and more important to resolve exhaustion of chemical fuels and environmental pollution. Polymer electrolyte membrane fuel cell has been widely studied to the extent that it can be used commercially. But there are many problems to be solved. One of them is to enhance the stability of fuel cell stacks. This paper proposes a new fault diagnosis method using Least Square Method (LSM) which is one of parameter estimation methods. The proposed method extracts equivalent circuit parameters from on-line measurements. Parameters of the circuit are estimated according to normal and abnormal states using simulation. The variation of parameters estimated in each states enables the estimation of state in fuel cells. Thus the LSM presented can be a suitable on-line parameter estimation method in PEMFC.

• Transactions of the Korean hydrogen and new energy society
• /
• v.23 no.5
• /
• pp.468-475
• /
• 2012

A proper stacking force and assembly are important to the performance of fuel cell. Improper assembly pressure may lead to leakage of fuels and high interfacial contact resistance, excessive assembly pressure may result in damage to the gas diffusion layer and other components. The pressure distribution of gas diffusion layer is important to make interfacial contact resistance less for stack performance. To analyze the influence of design parameter factors for pressure distribution, and to optimize stack design, DOE (Design of Experiment) was used for polymer electrolyte membrane fuel cell stack pressure test. As commonly known, the higher clamping force improves the fuel cell stack performance. However, non-uniformity of stress distribution is also increased. It shows that optimization between clamping force and stress distribution is needed for well designed structure of fuel cell stack. In this study, stack design optimization method is suggested by using FEM (Finite Element Methode) and DOE for light-weighted fuel cell stack.

• Journal of Electrochemical Science and Technology
• /
• v.1 no.2
• /
• pp.92-96
• /
• 2010

A new synthesis method for the preparation of Pt electrocatalysts on carbon nanofibers (CNFs) is reported. In this method, Pt electrocatalysts are loaded onto 2-naphthalenethiol (NT) functionalized CNFs. The noncovalent functionalization of CNFs by NT is the effective way for better distribution of Pt particles and higher electrocatalytic activity in polymer electrolyte membrane fuel cells. It was found that the presence of NT acts as a poison to catalysts. Therefore, it is necessary to remove NT through the heat treatment at $400^{\circ}C$.

• Applied Chemistry for Engineering
• /
• v.33 no.6
• /
• pp.646-652
• /
• 2022

The dead-end anode (DEA) system is a method that closes the anode outlet and supplies fuel by pressure. The DEA method could improve fuel usage and power efficiency through system simplification. However, flooding occurs due to water and nitrogen back diffusion from the cathode to the anode during the DEA operation. Flooding is a cause of decreased fuel cell performance and electrode degradation. Therefore, tthe structure and components of polymer electrolyte membrane fuel cell (PEMFC) should be optimized to prevent anode flooding during DEA operation. In this study, the effect of a porous flow field with metal foam on fuel cell performance and fuel efficiency improvement was investigated in the DEA system. As a result, fuel cell performance and purge interval were improved by effective water management with a porous flow field at the cathode, and it was confirmed that cathode flow field structure affects water back-diffusion. On the other hand, the effect of the porous flow field at the anode on fuel cell performance was insignificant. Purge interval was affected by metal foam properties and shown stable performance with large cell size metal foam in the DEA system.

• Journal of the Korean Electrochemical Society
• /
• v.10 no.4
• /
• pp.279-282
• /
• 2007

When reformer for fuel cell is used, CO in hydrogen gas leads to a seriously decreased membrane electrode assembly (MEA) performance by catalyst poisoning. The effect of CO on performance of modified MEA by sputtering method is studied in this paper. The experimental results show that sputtered Pt and Ru thin film improve a single cell performance of MEA and sputtered metal thin film has a CO tolerance. The air injection process on anode show improved CO tolerance test result. Moreover, Pt, Ru and PtRu thin film by sputtering had influence on the CO tolerance with air injection process.