Graphene Oxide-Hydrogen Membrane Fuel Cell

Md Shahjahan Kabir Chowdury,박성범,박용일 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.7 No.3

Proton exchange membrane fuel cell (PEMFC) utilizes polymer electrolyte membrane, e.g., Nafi on™, which is a perfl uorosulfonic acid (PFSA) membrane with many disadvantages such as expensive, low mechanical strength, low chemical stability at high temperatures. Meanwhile, graphene oxide membrane (GOM) is an excellent proton conductor at room temperature under humidifi ed conditions. However, graphene oxide membrane fuel cells (GOMFCs) exhibit low maximum power density compared to Nafi on due to fuel gas crossover, membrane degradation and loss of surface functionalities. In this study, bilayer membrane consisting of GOM and hydrogen permeable metal thin fi lm was investigated as electrolyte membrane for hydrogen membrane fuel cell (HMFC). In this fuel cell, the graphene oxide-hydrogen membrane (GOHM) simultaneously plays two roles, an anode catalyst and an electrolyte. A hydrogen permeable metal thin fi lm of about 40 nm was deposited by DC magnetron sputtering at a suitable pressure and deposition time on a 12 μm-thick GOM using a Pd or Ni 64 Zr 36 target to complete the bilayer GOHM electrolyte. The fuel cell performance of the GOHMFC using with Pt-free anode was compared with the GOHMFC with conventional Pt/C electrodes and conventional PEMFC.

Ridge and field tile aerodynamics for a low-rise building: a full-scale study

Tecle, Amanuel,Bitsuamlak, Girma T.,Suskawang, Nakin,Chowdury, Arindam Gan,Fuez, Serge Techno-Press 2013 Wind and Structures, An International Journal (WAS Vol.16 No.4

Recent major post-hurricane damage assessments in the United States have reported that the most common damages result from the loss of building roof coverings and subsequent wind driven rain intrusion. In an effort to look further into this problem, this paper presents a full-scale (Wall of Wind --WoW--) investigation of external and underneath wind pressures on roof tiles installed on a low-rise building model with various gable roofs. The optimal dimensions for the low-rise building that was tested with the WOW are 2.74 m (9 ft) long, 2.13 m (7 ft) wide, and 2.13 m (7 ft) high. The building is tested with interchangeable gable roofs at three different slopes (2:12; 5:12 and 7:12). The field tiles of these gable roofs are considered with three different tile profiles namely high (HP), medium (MP), and low profiles (LP) in accordance with Florida practice. For the ridge, two different types namely rounded and three-sided tiles were considered. The effect of weather block on the "underneath" pressure that develops between the tiles and the roof deck was also examined. These tests revealed the following: high pressure coefficients for the ridge tile compared to the field tiles, including those located at the corners; considerably higher pressure on the gable end ridge tiles compared to ridge tiles at the middle of the ridge line; and marginally higher pressure on barrel type tiles compared to the three-sided ridge tiles. The weather blocking of clay tiles, while useful in preventing water intrusion, it doesn't have significant effect on the wind loads of the field tiles. The case with weather blocking produces positive mean underneath pressure on the field tiles on the windward side thus reducing the net pressures on the windward surface of the roof. On the leeward side, reductions in net pressure to a non-significant level were observed due to the opposite direction of the internal and external pressures. The effect of the weather blocking on the external pressure on the ridge tile was negligible.

Sources of Carbonaceous Materials in the Airborne Particulate Matter of Dhaka

Begum, Bilkis A.,Hossain, Anwar,Saroar, Golam,Biswas, Swapan K.,Nasiruddin, Md.,Nahar, Nurun,Chowdury, Zohir,Hopke, Philip K. Korean Society for Atmospheric Environment 2011 Asian Journal of Atmospheric Environment (AJAE) Vol.5 No.4

To explore the sources of carbonaceous material in the airborne particulate matter (PM), comprehensive PM sampling was performed (3 to 14 January 2010) at a traffic hot spot site (HS), Farm Gate, Dhaka using several samplers: AirMetrics MiniVol (for $PM_{10}$ and $PM_{2.5}$) and MOUDI (for size fractionated submicron PM). Long-term PM data (April 2000 to March 2006 and April 2000 to March 2010 in two size fractions ($PM_{2.2}$ and $PM_{2.2-10}$) obtained from two air quality-monitoring stations, one at Farm Gate (HS) and another at a semi-residential (SR) area (Atomic Energy Centre, Dhaka Campus, (AECD)), respectively were also analyzed. The long-term PM trend shows that fine particulate matter concentrations have decreased over time as a result of government policy interventions even with increasing vehicles on the road. The ratio of $PM_{2.5}/PM_{10}$ showed that the average $PM_{2.5}$ mass was about 78% of the $PM_{10}$ mass. It was also found that about 63% of $PM_{2.5}$ mass is $PM_1$. The total contribution of BC to $PM_{2.5}$ is about 16% and showed a decreasing trend over the years. It was observed that $PM_1$ fractions contained the major amount of carbonaceous materials, which mainly originated from high temperature combustion process in the $PM_{2.5}$. From the IMPROVE TOR protocol carbon fraction analysis, it was observed that emissions from gasoline vehicles contributed to $PM_1$ given the high abundance of EC1 and OC2 and the contribution of diesel to $PM_1$ is minimal as indicated by the low abundance of OC1 and EC2. Source apportionment results also show that vehicular exhaust is the largest contributors to PM in Dhaka. There is also transported $PM_{2.2}$from regional sources. With the increasing economic activities and recent GDP growth, the number of vehicles and brick kilns has significantly increased in and around Dhaka. Further action will be required to further reduce PM-related air pollution in Dhaka.

Sources of Carbonaceous Materials in the Airborne Particulate Matter of Dhaka

Bilkis A. Begum,Philip K. Hopke,Anwar Hossain,Golam Saroar,Swapan K. Biswas,Md. Nasiruddin,Nurun Nahar,Zohir Chowdury 한국대기환경학회 2011 Asian Journal of Atmospheric Environment (AJAE) Vol.5 No.4

To explore the sources of carbonaceous material in the airborne particulate matter (PM), comprehensive PM sampling was performed (3 to 14 January 2010)at a traffic hot spot site (HS), Farm Gate, Dhaka using several samplers: AirMetrics MiniVol (for PM_10and PM_2.5) and MOUDI (for size fractionated submicron PM). Long-term PM data (April 2000 to March 2006 and April 2000 to March 2010 in two size fractions (PM2.2 and PM_2.2-10) obtained from two air quality-monitoring stations, one at Farm Gate (HS) and another at a semi-residential (SR) area (Atomic Energy Centre, Dhaka Campus, (AECD)), respectively were also analyzed. The long-term PM trend shows that fine particulate matter concentrations have decreased over time as a result of government policy interventions even with increasing vehicles on the road. The ratio of PM_2.5/PM_10 showed that the average PM_2.5 mass was about 78% of the PM10 mass. It was also found that about 63% of PM_2.5 mass is PM_1. The total contribution of BC to PM_2.5 is about 16%and showed a decreasing trend over the years. It was observed that PM_1 fractions contained the major amount of carbonaceous materials, which mainly originated from high temperature combustion process in the PM_2.5. From the IMPROVE TOR protocol carbon fraction analysis, it was observed that emissions from gasoline vehicles contributed to PM_1 given the high abundance of EC1 and OC2 and the contribution of diesel to PM_1 is minimal as indicated by the low abundance of OC1 and EC2. Source apportionment results also show that vehicular exhaust is the largest contributors to PM in Dhaka. There is also transported PM_2.2 from regional sources. With the increasing economic activities and recent GDP growth,the number of vehicles and brick kilns has significantly increased in and around Dhaka. Further action will be required to further reduce PM-related air pollution in Dhaka.