• Journal of the Korean Electrochemical Society
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• v.8 no.4
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• pp.149-154
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• 2005

Fuel cell performance evaluation logic was developed using G-language (LabVIEW) to measure performance stability. Degree of stability and reliability of performance data were improved with averaged value and standard deviation method. Water injection system was introduced and the performance using this method was comparable to that of conventional humidification method. Water injection system has advantage of lowering operation energy consumption, reducing the number of parts needed in humidification, therefore increasing efficiency of fuel cell system. Fuel cell performance was decreased in case of low temperature operation such as sub freezing condition. Air purge method was tested to reduce the water content in cell fixture before sub freezing condition. The performance degradation due to low temperature operation was minimized by air purge method in medium size cell fixture ($25cm^2$) case.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.339-344
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• 2005

A PEMFC system model for FCEV was constructed and simulated numerically to examine the heat/water flow of the system and air/fuel humidification process for various operation conditions (ambient pressure /temperature/humidity, operating temperature, power load). We modeled PEMFC stack which can generate maximum electricity of about 80 kW. This stack consists of 400 unit cells and each unit cell has $250cm^2$ reacting area. Uniform current density and uniform operating voltage per each cell was assumed. The results show the flow characteristics of heat and water at each component of PEMFC system in macro-scale. The capacity shortage of the radiator occurred when the ambient was hot $(over\;40^{\circ}C)$ and power level was high (over 50 kW). In spite of some heat release by evaporation of water in stack, heat unbalance reached to 20kW approximately in such a severe operating condition. This heat unbalance could be recovered by auxiliary radiators or high speed cooling fan with additional cost. In cold environment, the capacity of radiator exceeded the net heat generation to be released, which may cause a problem to drop the operating temperature of stack. We dealt with this problem by regulating mass flow rate of coolant and radiator fan speed. Finally, water balance was not easily broken when we retrieved condensed and/or unused water.

• Membrane Journal
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• v.20 no.4
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• pp.326-334
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• 2010

In this study, characterization and performance of membrane humidifier using membrane distillation was evaluated for moisture of fuel gas in the PEMFC. The data were expressed dew point. The best results show $51.19^{\circ}C$ at $60^{\circ}C$ of water temperature, $54.22^{\circ}C$ at 900 mL/min and $60.03^{\circ}C$ at 100 strands. The mass transfer modelling of membrane humidifier were able to predict humidification of fuel gases for operating PEMFC. When the membrane humidifier was applied to the 100 W stack, it showed stable voltage and power. The volume of membrane humidifier was small however, showed better performance than bubble humidifier.

• Journal of Korean Clinical Nursing Research
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• v.15 no.1
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• pp.43-53
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• 2009

Purpose: This study aimed to compare the moisturizing effect of cold water gargling, wet gauze application and humidification in reducing thirst and mouth dryness after nasal surgery. Method: Patients were randomly assigned into three groups of 19 subjects each. In the two intervention groups, each group was received hourly cold water gargling or wet gauze application for 4 hours postoperatively. In the control group, the subjects were received only humidification continuously on a bedside. We compared the thirst and oral condition at 0, 2, 4hours. after operation. Thirst was measured using VAS questionnaire, and oral condition(mouth dryness) by Oral Assessment Guide. Results: There was a significant difference among three groups in the level of thirst and mouth dryness. In the cold water gargling group, there was a significant decrease in thirst at 2, 4hours. In the wet gauze group, there was a significant decrease in thirst at 4hours. In the intervention group, there was a significant decrease in mouth dryness at 2, 4hours. In the control group, there was a significant decrease in mouth dryness at 4hours. Conclusion: The findings of this study suggest that the cold water gargling would be an effective nursing intervention to reduce thirst and mouth dryness postoperatively.

• Journal of Bio-Environment Control
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• v.29 no.3
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• pp.219-230
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• 2020

This study was conducted to determine the optimum medium and humidification period for the strawberry (Fragaria × ananassa Duch. cv. Maehyang) cutting seedling production. The cuttings were planted in coir (CO), rockwool (RW), phenolic foam (PF), and organic foam medium (OFM) with fogging treatment in 0, 3, 6, 9, or 12 days on February, 2019. And, as the field verification examination research, cuttings were planted in CO, RW, PF, and OFM, with misting treatment in 0, 6, 9, 12, or 15 days on June, 2019. In fogging treatments, rooting and survival rates of seedlings tended to increase with longer fogging periods, and rooting and survival rates were showed significantly higher in CO medium with more than 9 days of fogging periods. In misting treatments, rooting rate was significantly higher in CO and RW medium with more than 9 days of misting periods, and survival rate was significantly higher with more than 12 days of misting periods. There was no significantly difference by growth medium and humidification period in shoot and root growth. Therefore, when considering the rooting and survival rate the CO medium with 9 days of humidification period could be beneficial for the production of the 'Maehyang' strawberry cutting seedlings.

• Membrane Journal
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• v.21 no.1
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• pp.30-38
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• 2011

Composite membranes based on sulfonated poly(aryl ether) sulfone (SPAES) with different sulfated zirconia nanoparticles ($s-ZrO_2$) ratio are synthesized and investigated for the improvement of the hydration and the proton conductivity at high temperature and no humidification for fuel cell applications. X-ray diffraction technique is employed to characterize the structure and the size of $s-ZrO_2$ nanoparticles. The sulfation effect of $s-ZrO_2$ nanoparticles is verified by FT-IR analysis. The properties of the SPAES composite membranes with the various $s-ZrO_2$ ratio are evaluated by ion exchange capacity and water content. The proton conductivities of the composite membranes are estimated at room temperature with full hydration and at the various high temperature without external humidification. The composite membrane with 5 wt% $s-ZrO_2$ shows the highest proton conductivity. The proton conductivities are $0.9292\;S\;cm^{-1}$ at room temperature with full hydration and $0.0018\;S\;cm^{-1}$ at $120^{\circ}C$ without external humidification, respectively.

• Proceedings of the Korean Society of Crop Science Conference
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• 1997.05a
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• pp.92-93
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• 1997

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.1
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• pp.82-91
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• 2005

Polymer membrane needs to maintain appropriate moisture. Insufficient moisture causes low conduction of hydrogen ion because of increased contact resistance between electrode and membrane by shrinking membrane, and abundant moisture decreases fuel cell performance as difficulty of diffusion reacting gas. Therefore, water controlling system is very consequential for the polymer membrane fuel cell. If hollow fiber membrane humidification is used between fuel and air lines, it is possible to supply heat to fuel and air by using thermal exchanger. It can supply appropriate humidity depending on operating temperature, and can recover heat from exhaust gas which contains water vapor and air. Because of simple structure of humidification system, this system can be easily applied in the PEMFC and cut down cost.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.7 s.262
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• pp.588-595
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• 2007

The water transport inside a polymer electrolyte fuel cell (PEFC) varied according to the anodic supply mode. The performance characteristics of a PEFC which can be affected by the water transport were observed with the anodic supply mode. In the flow-through and recirculation mode the performance showed no reduction with time because the flow in the anode was not stagnated. In the dead-end mode, without any discharged gas, the water remains inside of the anode, which caused the reduction of the performance with the lapse of time. However, even in the dead-end mode, little reduction of the performance with time was shown when only the anode was humidified externally. It means that the back-diffusion was the major factor to the accumulation of water in the anode rather than external humidification.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.98.2-98.2
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• 2011

For optimal performance of a proton exchange membrane fuel cell (PEMFC), the membrane electrode assembly (MEA) requires hydration, and the membrane's conductivity depends on water content. A humidifier is required to ensure that the reactant gas, usually hydrogen and air, is hydrated before entering the fuel cell. Dry membrane operation or improper hydration causes performance degradation. Typically, the humidification of a fuel cell is carried out by means of an internal or external humidifier. A membrane humidifier is applied to the external humidification of transportation or residential power generation fuel cell due to its convenience and high performance. In this study, The experiments were constructed with a plate-type membrane humidifier in terms of geometric parameters and operating parameters. The results show that the temperature and pressure, the channel length, the membrane thickness and gas flow rate are critical parameters affecting the performance of the humidifier.