• Journal of Hydrogen and New Energy
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• v.19 no.1
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• pp.26-34
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• 2008

This study presents an aerodynamic design and an experimental performance test of a turbo air compressor consisted of mixed-flow impeller and curved diffuser for the PEM fuel cell vehicle application. Many studies compare the efficiency, cost or noise level of high-pressure and low-pressure operation of PEM fuel cell systems. Pressure ratio 2.2:1 is considered as design target The goal of compressor design is to enlarge the flow margin of compressor from surge to choke mass flow rate to cover the operational envelope of FCV. Large-scale rig test is performed to evaluate the compressor performance and to compare the effects of compressor exit pipe volume to stall or surge characteristics. The results show that the mixed-flow compressor designed has large flow margin, and the flow margin of compressor configuration with small exit volume is larger than that with large exit volume.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.152-155
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• 2007

Fuel cell electric vehicles (FCEVs) using hydrogen gas are zero emission vehicles, thus emission measurement for combustion vehicles is not applicable. The hydrogen gas consumption for fuel economy will be measured by the stabilized pressure/temperature method, mass flow method and electrical current method, etc. In this research, weight method with a newly manufactured test equipment is applied to measure the hydrogen consumption because above 3-methods have a deviation. The hydrogen consumption is directly calculated by the weight differences of the external hydrogen tank before and after the chassis dynamometer test. Ultimately the fuel economy for FCEVs is obtained with a deviation less than 1% in all chassis dynamometer tests.

• Journal of Hydrogen and New Energy
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• v.15 no.3
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• pp.175-186
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• 2004

In this paper, we developed the dynamic model of a fuel cell system suitable for controller design and system operation. The transient phenomena captured in the model include the flow characteristics and inertia dynamics of the compressor, the intake manifold filling dynamics, oxygen partial pressures and membrane humidity on the fuel cell voltage. In the simulations, we paid attention to the transient behavior of stack voltage and compressor pressure, stoichiometric ratio. Simulation results are presented to demonstrate the model capability. For load current following, stack voltage dynamic characteristics are plotted to understand the Electro-chemistry involved with the fuel cell system. Compressor pressure and stoichiometric ratio are strongly coupled, and independent parameters may interfere with each other, dynamic response, undershoot and overshoot.

• Journal of Hydrogen and New Energy
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• v.27 no.2
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• pp.155-162
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• 2016

A proton exchange membrane fuel cell (PEMFC) produces only water at cathode by an electrochemical reaction between hydrogen and oxygen. The generated water is transported across the membrane from the cathode to the anode. The transported water collected in water-trap and drained to the cathode within the humidifier outlet. If the condensate water is not being drained at the appropriate time, condensate water in the anode can cause the performance degradation or fuel efficiency degradation of fuel cell by the anode flooding or unnecessary hydrogen discharge. In this study, we proposed an optimization method of condensate water drain logic for the water drain performance and the water drain algorithm as considered the condensate water generating speed prep emergency case. In conclusion, we developed the water management strategy of fuel processing system (FPS) as securing fuel efficiency and operating stability.

• Journal of Hydrogen and New Energy
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• v.17 no.3
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• pp.279-285
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• 2006

Recirculation for the unreacted fuel is necessary to improve the overall efficiency of the fuel cell system and to prevent fuel starvation since the fuel cell for a vehicle application is a closed system. In case of the automotive fuel cell, the ejector which does not require any parasitic power is good for the performance improvement and easy operation. It is essential to design the customized ejector due to the lack of the commercial ejector corresponding to the operating conditions of the fuel cell systems. In this study, the design methodology for the ejector customized to an automotive fuel cell is proposed. The model based sensitivity analysis prevents the time-consuming redesign and reduces the cost of developing ejector. As a result, the customized ejector to meet the desired performance within overall operating range has developed for the PEMFC automotive system.

• Journal of Hydrogen and New Energy
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• v.23 no.5
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• pp.484-492
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• 2012

The TMS(Thermal Management System) heater in a fuel cell vehicle has been developed to prevent a decline of fuel cell durability and cold start durability. Main functions of the COD(Cathode Oxygen Depletion) heater are depletion of oxygen in a cathode as heat energy and consumption of electric power for rapid warming up of a fuel cell stack. This paper covers subjects including the design specification of a heater, heater controller for detection of overheat and reliability assessment including coolant pressure cycle test of a heater. To verify the design concept, burst pressure and deformation analysis of plastic housing were carried out. Also, temperature distribution analysis of heater surface and coolant inside of housing were carried out to verify the design concept. By designing the plastic housing instead of a steel housing, the 30% weight lightening and 50% cost reduction were attained. A module-based design of a TMS system including a heater or reducing the watt density of a heater is a problem to be solved in the near future work.

• Journal of Digital Convergence
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• v.19 no.5
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• pp.279-284
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• 2021

In this study, the performance and distribution of fluid concentration, pressure, and current density of a proton exchange membrane fuel cell was investigated. In this paper, the two different types of flow field design were compared, singel channel and 5-channels. As a result, the 5-channels of flow field showed the better performance than that of single chanel. Especially, the single channel showed better performance in terms of mass transfer loss area.

• Journal of Hydrogen and New Energy
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• v.23 no.4
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• pp.316-322
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• 2012

A fuel cell vehicle has the hydrogen detection sensors for checking the hydrogen leakage because it use hydrogen for its fuel and can't use a odorant to protect the fuel cell stack. To verify the hydrogen safety of leakage we select the high possible leak points of fittings in hydrogen storage system and test the leaking behavior at them. The hydrogen leakage flow rate is 10, 40, 118 NL/min and the criterion for maximum hydrogen leakage is based on allowing an equivalent release of combustion energy as permitted by gasoline vehicles in FMVSS301. There are total 18EA hydrogen leakage detection sensors installed in test system. we acquire the hydrogen leakage detection time and determine the ranking. Hydrogen leakage detection time decrease when hydrogen leakage flow rate increase. The minimum hydrogen leakage detection time is about 3 seconds when the flow rate is 118NL/min. In this study, we optimize hydrogen sensor position in fuel cell vehicle and verify the hydrogen leakage safety because there is no inflow inside the vehicle.

• Journal of Hydrogen and New Energy
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• v.21 no.3
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• pp.167-183
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• 2010

This paper analyzes the backgrounds of the standards for protection against electric shock in Global Technical Regulations (GTR) of Fuel Cell Vehicle (FCV). Targets on research were high voltage criteria, safety current, isolation and grounding resistance, time limitation, energy, adequate clearance, and test procedure. Based on human impedance and effect of current in IEC 60479-1, safety of human was examined. Then, isolation and grounding circuit model of FCV were analyzed theoretically. The results give several suggestions: touch voltage less than 25V, AC energy less than 0.0813J, separation considering middle finger length, grounding resistance less than $0.2\Omega$, maximum AC ground voltage of 1V (rms), and isolation resistance between earth and electrical chassis. In MATLAB/Simulink environment, error characteristics of isolation resistance measurement procedure using internal DC sources were analyzed under variations of internal resistance of voltmeter and isolation resistance.

• Journal of Hydrogen and New Energy
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• v.22 no.6
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• pp.852-858
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• 2011

This paper is aiming to estimate the mutual influence of the stack cooling performances with the operation modes of the thermal management system for the hydrogen fuel cell vehicles. The heat capacity of the thermal management system was measured by varying the operating modes such as stack cooling heat exchanger only (Mode 1), stack cooling and electric devices cooling heat exchangers (Mode 2), and stack cooling and electric devices cooling heat exchangers with an operation of the condenser (Mode 3).As the results, Performance of the thermal management system (TMS) at Mode 3 decreased up to 34.0%, compared with the result of the Mode 1. In addition, in order to optimize the performance of TMS, the entropy change of stack cooling heat exchanger using irreversibility analysis technique was analyzed with the relationship between entropy generation and entering air velocity of the thermal management system.