The effect of the pore structure and thickness of the porous carbon plate, PCP, as well as the gas barrier thickness on the methanol transport and the performance of a passive DMFC under the ...different cell voltages of 0.1, 0.2 and 0.3
V using different methanol concentrations was investigated. As a result of the mass transfer restrictions by employing the PCP, high methanol concentrations over 20
M could be efficiently used to produce the relatively high power density of 30
mW
cm
−2 for more than 10
h. The DMFC was operated under limiting current conditions in all the PCPs at 0.1 and 0.2
V to more than 20
M. The main factors for controlling the methanol transport were the barrier of the gas layer with CO
2, which was formed between the anode surface and the PCP and the properties of the PCP. At the low current densities of less than 60
mA
cm
−2, when no CO
2 bubbles are emitted, both the pore structure and thickness of the PCP did not affect the methanol transport and the current voltage relationship. At the higher current densities, CO
2 bubbles were evolved through the PCP and different resistances to the methanol transport were observed depending on the PCP pore structure and thickness. The CO
2 gas layer between the MEA and the PCP caused a major resistivity for the methanol transport, and its resistivity increased with its thickness increasing. By using the PCP at 0.1
V, the energy density of the passive DMFC was significantly increased, e.g., more than seven times.
Water transport in a vapor feed direct methanol fuel cell was improved by fixing a hydrophobic air filter (HAF) at the cathode. Effects of the HAF properties and the fixed positions, i.e., just on ...the cathode surface or by providing a certain space from the surface, of the HAF on the water transport as well as the power generation performance were investigated. The water transport was evaluated by measuring the partial pressure of water,
P
H
2
O
, and methanol,
P
C
H
3
OH
, at the anode gas layer using in situ mass spectrometry with a capillary probe and also the water and methanol fluxes across the electrode structure using a conventional method. The HAF with the highest hydrophobicity and the highest flow resistance had the strongest effect on increasing the water back diffusion from the cathode to the anode through the membrane and increasing the current density. It was noted that the HAF fixation by providing a space from the cathode surface was more effective in increasing JWCO and the current density than that of the direct placement on the cathode surface. There was an optimum distance for the HAF placement depending on the humidity of the outside air.
Vertical operation of a passive DMFC employing a porous carbon plate, PCP, with different resistances for fluid flow and bubble point pressure was investigated to clarify the properties required for ...the PCP for vertical operation. Moreover, the cell performance was investigated under different solution head pressures within 22
mm height and was discussed based on the methanol transport through the PCP. In contrast to the horizontal orientation, the static pressure of the liquid as a function of its height on the vertical axis
h along the PCP surface, in the vertical orientation, enhanced the convective methanol flux through the PCP and affected the DMFC performance depending on the properties of the PCP and the methanol concentration used. The effect of the solution head pressure on the DMFC performance in the vertical orientation could be controlled by using PCP with high bubble point pressures. The DMFC could attain stable performance under both horizontal and vertical cell orientations and different solution head pressures even with 100% methanol by using a PCP with the proper resistance for the methanol transport and bubble point pressure. A thin PCP of 0.5
mm thickness with the proper resistance enabled the vertical operation producing a constant power density over 40
mW/cm
2 using 100% methanol at 0.25
V.
It is known that a small amount of intermediate products, i.e., formaldehyde, formic acid and so on, is exhausted from a direct methanol fuel cell (DMFC). The production rates of such intermediates ...are affected by the methanol and water concentrations at the anode, and also the distribution of these products is variable. We investigated the production of the intermediates from a passive DMFC containing a porous carbon plate (PCP), which allows the use of methanol at high concentrations up to 100% due to the high resistivity to the methanol transport through the PCP. The production rates of each intermediate and their distribution were measured not only for a DMFC employing various PCPs with different transportation resistivities, but also for a DMFC without PCP. The results were analyzed in terms of the rate of methanol crossover (MCO) and water flux through the membrane. The detected intermediates were formaldehyde, formic acid, and methylformate, in accordance with previous reports. The production rates of the intermediates were strongly dependent on the flux of the MCO rather than the apparent methanol concentration. When the DMFC was operated under the rate limiting conditions of the methanol transport by the PCP, the production rates of the intermediates were low. However, when it was operated outside of the rate limiting conditions, the production rate increased with the increasing rate of methanol crossover.
With the development of modern technology, high-performance running shoes play a critical role in improving athletes' running performance. Kipchoge (Eliud Kipchoge) first used carbon board running ...shoes in large events in 2017, and achieved remarkable results. In recent years, he has broken the marathon world record many times, among which, the role of carbon board running shoes canbe overlooked. This paper is intended to discuss the optimized design of carbon board running shoes to further improve the running efficiency and reduce energy expenditure in athletes. First, a photomechanical model 1 considering the characteristics of running shoes and athletes, and the genetic algorithm 2 and simulated anneal 3 were developed to find the best sole side profile shape. Through the optimization, the comfort and stability of the sole are significantly improved. Then, we embedded the full-length carbon plates in the sole and built the carbon plate mechanical model 4. The optimization results show that the embedded carbon plate can effectively reduce energy consumption, increase the efficiency of running pace and running shoe performance. Finally, we re-optimized the side profile of the sole and the carbon plate parameters, so that the side profile of the sole showed a more stable curve, the warping of the toe and heel is reduced, and the sole has higher mechanical efficiency.
In situ mass spectroscopy with a capillary probe was conducted for the anode gas layer of a semi-passive direct methanol fuel cell (DMFC) employing a porous carbon plate (PCP) in order to evaluate ...the gas composition in contact with the anode. Different types of PCPs were used for the DMFC, and then the relationship between the gas composition in the gas layer and the current density was investigated. The profiles of the CO
2 gas pressure, methanol and water vapor pressures were discussed on the basis of the current density and the resistance for the methanol and CO
2 transport through the PCP. The current density linearly and identically increased with the increase in the partial pressure of methanol,
P
C
H
3
OH
, in the gas layer up to 7.5
kPa irrespective of the type of the PCP suggesting that the current was a function of
P
C
H
3
OH
and it was rate limited by the methanol transport to the anode. The calculated liquid methanol concentration equivalent to the measured gas mixture in the gas layer was about 5–7
M in the optimum conditions. This confirmed that the actual methanol activity on the anode of the DMFC with the PCP was controlled by the PCP and was similar to that of the usual liquid feed DMFC even when a very high concentration of methanol was in the reservoir.
Abstract Introduction The aim of this study was to compare a carbon plate (CP) and a titanium mandibular reconstruction plate (TMRP) in finite element analysis and an animal model. Materials and ...methods Twelve rabbits were used for this experiment. After a mandible continuity defect was created, either a CP or a TMRP was used for mandibular reconstruction. Postoperatively, daily feed intake amount (DFIA) was measured for 4 weeks. Radiographic images were also acquired to evaluate screw loosening. For the analysis of the stress distribution, a simple continuity defect model was used, and finite element analysis was performed. Results The CP group had 0.80 ± 0.45 lost screws in an animal during the 4 weeks postoperative observation; however, the TMRP group had 1.86 ± 0.69 lost screws ( p = 0.014). Overall, the 5 out of 5 of rabbits in the CP group and 3 out of 7 in the TMRP group exhibited preoperative levels of DFIA during the 4 week observation ( p = 0.038). The finite element analysis showed that the stress was more evenly distributed in the CP than in the TMRP model. Conclusions The CP group showed decreased screw loosening and increased recovery of preoperative DFIA compared to the TMRP group in a rabbit model of mandibular continuity defects. Perfect adaptation of CP during the operation could not be achieved in spite of reshaping to the mandibular curvature. This disadvantage of the CP system can be overcome by the prefabricated technique using a prototype model.
► Power degradation occurred in a direct methanol fuel cell (DMFC) with a plastic tube was investigated. ► Di-(2-ethylhexyl) phthalate (DEHP), a plasticizer, was detected in the circulated methanol ...solution. ► The degradation in performance by DEHP was confirmed. ► DEHP would affect the methanol transport through the PCP.
The cause of the power degradation that occurred in a direct methanol fuel cell (DMFC) with a plastic tube for the connection was investigated. The DMFC had a unique electrode structure with a porous carbon plate in order to control the methanol crossover, and then operated with a 99.8wt% methanol solution. A certain amount of di-(2-ethylhexyl) phthalate (DEHP), a plasticizer, was detected in the circulated methanol solution. The degradation in performance by DEHP was confirmed by comparing the performances with and without DEHP addition in the methanol. It was postulated that the methanol transport through the PCP was significantly affected by the addition of DEHP.
As one of the basic areas of research for the improvement of the electromagnetic environment, this paper has developed a carbon plate having orientation characteristics. To exhibit the orientation ...characteristics in a plane wave, a slit was cut on the surface of a carbon plate. The value of the radio frequency (RF) magnetic shielding degree SD HP when holding the slit in the carbon plate perpendicularly, in the frequency region from 1 MHz to 1 GHz, increased with frequency and had a value of 48 dB at 1 GHz. It was also shown that the value of SD HH when holding the slit horizontally indicated about 15 dB in the frequency region from 1 MHz to 1 GHz. Namely, the difference in the values of shielding degree of the carbon plate versus the orientation of slit indicated the characteristics of the orientation. Experimental results revealed several characteristics of the slit carbon plate that include the influences of the slit length L , slit number N , and slit width w on the characteristics of the orientation. In this paper, the orientation characteristics were improved by the superposition of a slit ferrite plate over a slit carbon plate, termed the compound plate. In addition, important criteria are discussed for the design of a plate for effective RF magnetic shielding having orientation characteristics.
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