• Transactions of the Korean hydrogen and new energy society
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• v.26 no.2
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• pp.127-135
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• 2015

High-Temperautre Polymer Electrolyte Membrane Fuel Cell (HT-PEMFC) with phosphoric acid-doped polybenzimidazole (PBI) membrane has high power density because of high operating temperature from 100 to $200^{\circ}C$. In fuel cell stack, heat is generated by electrochemical reaction and high operating temperature makes a lot of heat. This heat is caouse of durability and performance decrease about stack. For these reasons, heat management is important in HT-PEMFC. So, we developed HT-PEMFC model and study heat flow in HT-PEMFC stack. In this study, we placed coolant plate number per cell number ratio as variable and analysed heat flow distribution in stack.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.4
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• pp.377-383
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• 2017

This paper presents the performance characteristics of a 1 kW solid oxide fuel cell (SOFC) stack under various internal reforming and fuel utilization conditions. The Research Institute of Industrial Science & Technology (RIST) developed the 9-cell stack using a $20{\times}20cm^2$ anode supported planar cell with an active area of $324cm^2$. In this work, current-voltage characteristic test, fuel utilization test, continuous operation, and internal reforming test were carried out sequentially for 765 hours at a furnace temperature of $700^{\circ}C$. The influence of fuel utilization and internal reforming on the stack performance was analyzed. When the 1 kW stack was tested at a current of 145.8 A with a corresponding fuel utilization of 50-70% (internal reforming of 50%) and air utilization of 27%, the stack power was approximately 1.062-1.079 kW. Under continuous operation conditions, performance degradation rate was 2.16%/kh for 664 hours. The internal reforming characteristics of the stack were measured at a current of 145.8. A with a corresponding fuel utilization of 60-75%(internal reforming of 50-80%) and air utilization of 27%. As fuel utilization and internal reforming ratio increased, the stack power was decreased. The stack power change due to the internal reforming ratio difference was decreased with increasing fuel utilization.

• Wind and Structures
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• v.12 no.4
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• pp.333-347
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• 2009

Many tower-supported steel stacks have been constructed in Japan, primarily for economic reasons. However the dynamic behavior of these stacks under a strong wind is not well known and the wind load design standard for this type of a stack has not yet been formulated. In light of this situation, we carried out wind response observation of an operating tower-supported steel stack with and without a tuned-mass damper. The observation revealed the performance of the tuned-mass damper installed on the stack in order to control the wind-induced vibration. Based on the observed data, we performed a wind tunnel test of a specimen of the stack. In this paper we report the results of the wind tunnel test and some comparisons with the results of observation. Our findings are as follows: 1) the tuned-mass damper installed on the specimen in the wind tunnel test worked as well as the one on the observed stack, 2) the amplitude of the vortex-induced vibration of the specimen corresponded approximately to that of the observed stack, and 3) correlation between Scruton number and reduced amplitude, y/d, (y is amplitude, d is diameter) was confirmed by both the wind tunnel test and the observed results.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.284-292
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• 2009

The stack-effect in high-rise buildings in winter causes many problems such as difficulties in opening or closing doors, infiltration, energy loss, noise and fire protection. Stack effect is influenced by temperature difference between the interior and exterior of building and the height of building. As an attenuation method for stack effect, the architectural methods are generally used. However, as though architectural methods were fully adopted, the problems are reported as ever in tall building. In this study, a new method to reduce stack effect will be suggested. As an active control method against the stack effect, E/V shaft natural cooling method is suggested. In this paper, the concept of E/V shaft natural cooling system and its reduction performance of stack effect by simulation and field measurement will be reported.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.3
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• pp.152-157
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• 2015

Stack effect on high-rise building have negative effect on living environment, energy and life-safety aspect. Thus, it's necessary to find the measure to reduce the stack effect. As a result of field test on a 31-story building, a circulating type stack effect reduction technology was developed, which supplies air in the low stairs and discharges air in the high stairs. To evaluate the performance of this circulating type stack effect reduction technology on building stairs, a 3D numerical analysis was carried out by using Momentum Loss Model for analyzing leakage flow between compartments in a building. Consequently, numerical analysis proved that the stack effect on building stairs was reduced by a circulating type stack effect reduction technology.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.292-298
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• 2009

This paper investigates the control performance of the proposed hybrid mount system for vibration isolation table. The hybrid mount system consists of an air spring as a passive device and a PZT stack actuator as an active device in series. The feasibility of the PZT stack actuator as an active actuator was examined through the simple experiments. After that, a series of numerical simulations were carried out to evaluate the control performance of the proposed hybrid mount system. The equations of motion of the table with a set of hybrid mount systems consisting of four devices are derived. The air spring is considered as a 1 spring and 1 dashpot elements, and PID control algorithm is adopted to estimate the control force. The results of the numerical simulations presents that the proposed hybrid mount system could be the promising control system for vibration isolation table.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2144-2148
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• 2008

Kerosene-driven solid oxide fuel cell (SOFC) system with reformer, desulfurizer and after-burner was mainly developed for this study. Originally the system was developed for 1kW class SOFC system for residential power generation (RPG) application. As a preliminary study of 1kW class SOFC system operation, a short stack was applied to the system. The short stack consists of 7 cells of $10cm{\times}10cm$ area and was operated at $720^{\circ}C$. The effect of anode inlet gas composition to stack performance was investigated. Firstly, I-V characteristics of SOFC with different fuel of kerosene and hydrogen were studied. Secondly $CH_4$ internal reforming was performed at various anode inlet gas compositions of $H_2$, $CH_4$ and $H_2O$. Through these experiments the effects of each anode inlet gas component to stack performance were analyzed and the significant operating parameters were iscussed.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1876-1878
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• 1999

Developed was a 5kW-class polymer electrolyte membrane fuel cell(PEMFC) system comprised of fuel cell stack, fuel processing, thermal and water management subsystems and ancillary equipments. Several large single cells have been fabricated with different gas flow field patterns and paths, and the gas flow field pattern for the stack has been determined based on the single cell performance of thin film membrane electrode assembly (MEA). The PEMFC stack was consisted of 100 cells with an electrode area of $300cm^2$, having serpentine flow pattern. Fuel processing was developed including an autothermal methanol reformer and two preferential CO oxidation reactors. The fuel processing was combined to PEMFC operation system consisted of air compressor and thermal and water management subsystems. The PEMFC stack showed performance of 5kW under the supply of $H_2$ and air, but its performance was lowered to 3.5kW under the supply of reformed gas.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1870-1872
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• 1999

Performance of 20-cell stack for direct methanol fuel cell (DMFC) was tested at constant temperature. Electrode evaluation used to the stack was tested by the performance of a single cell. A new composite electrode prepared from active carbon cloth and high porous active carbon was developed for hydrophilic layer of the cell. Characteristics of a single cell using the composite electrode showed the current density of $500mA/cm^2$ at the cell voltage of 0.4V at $120^{\circ}C$. For the operating of 20 days. the cell voltage at constant cell current densty of $100mA/cm^2$ was slightly reduced from 0.62V to 0.53V with the cell voltage decay rate of 14.5%. Power of 20-cell stack at 5.3V, $100^{\circ}C$ was about 180W.

• Journal of the Korean Ceramic Society
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• v.44 no.12
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• pp.720-726
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• 2007

Current collectors of SOFC play a significant role on the performance of power generation. In this study a single cell stacked SOFC was assembled using Ag-mesh as a cathode current collector, and evaluated its performance. No gas leakages of the single cell stack occurred in the tests of gas detection and OCV measurement. The OCV and initial power of the stack were 1.09V and $0.45W/cm^2$, respectively, under the flow rates of air at 2,500 cc/min and $H_2$ at 1,000 cc/min at the test temperature of $750^{\circ}C$. A degradation rate of 44.0% was measured during the prolonged time of 307 h. The relatively low durability of the tested single cell stack was found to be the evaporation of Ag-mesh at the current corrector.