A fuel cell is mainly used to provide electricity from chemical reactions. It harnesses the chemical energy of hydrogen and oxygen to generate electricity without combustion one of the basic types of fuel cells is the Polymer Electrolyte Membrane Fuel Cell (PEMFC). This section will give a general description of its parts, how do they function and the material they are consisted of. 3.2 Background Polymer electrolyte membrane fuel cells operate at relatively low temperatures, around 80°C (176°F). Low-temperature operation allows them to start fast (less warm-up time) and results in less wear on system components, which result in better durability. However, it requires that a noble-metal catalyst (typically platinum) be used to separate the hydrogen's electrons and protons, adding cost to the system. PEM fuel cells are used primarily for transportation applications and some stationary applications. Due to their fast startup time, low sensitivity to orientation, and favorable power-to-weight ratio, PEM fuel cells are particularly suitable for use in passenger vehicles, such as cars and buses. A significant barrier to using these fuel cells in vehicles is hydrogen storage. Most fuel cell vehicles (FCVs) powered by pure hydrogen must store the hydrogen on-board as a compressed gas in tanks. Due to the low-energy density of hydrogen, it is difficult to store enough hydrogen on-board to allow vehicles to travel the same distance as gasoline-powered vehicles before refueling. This increases costs and maintenance. They deliver high-power density and offer the advantages of low weight and volume, compared with other fuel cells. 3.3 PEMFC structure Figure PEMFC- 1 Polymer ... ... middle of paper ... ...for the fuel cell. [Lister & McLean ] • Electrolyte membrane: The electrolyte membrane is usually made of Nafion because its availability, low cost, low permeability, good chemical stability and strength. However, it is expensive. [Lister & McLean ] • Catalyst: The most widely used catalyst for PEM fuel cells is Platinum. Platinum catalyst layers are rough and porous to give larger surface area for Oxygen and Hydrogen to react with Pt. They can be as particles as well. [Wang 2011] • Current collectors, GDL and bipolar plates: Current collectors are made of graphitic materials due to its good conduction. GDL gas diffusion layers are made of carbon paper, which has low electronic resistance in order to provide maximum electronic contact and prevent water flooding. Bipolar plates are made of either graphite sot thermosets materials. [Lister & McLean ]
Gadolinium and its performance were limited by the use of passive regenerators and heat exchangers in the refrigeration cycle [25]. So, a magnetic refrigeration device must utilize a regenerative process to produce a large enough temperature span to be useful for refrigeration purposes [26].
Catalyst support must have a certain properties in order to enhance the catalytic activity. Thus in order to choose the most suitable support material it must have the certain physical and chemical properties. Among the properties are the catalyst support must be stable under reaction and regeneration condition, have high porosity for the mass and heat transport to be efficient and allow easy diffusion in and out , possess large surface area to increase the activity and distribution of the active components, ability to sustain and retain mechanical stability at high temperatures to prevent abrasion and increase durability of the catalyst on the support, possess high heat capacity and thermal conductivity in order to prevent the heat of adsorption igniting the powdered metal, and must be inert but reactive material.
The catalytic converter is a simple yet fascinating invention that uses precious metals such as platinum palladium, and rhodium as catalyst to cause reduction and oxidation reactions that can reduce dangerous gasses produced by combustion engines by over 95% converting them into less harmful gasses. Even though catalytic converters are quite simple they are still extremely expensive, this is due to the precious metals that are used as catalysts.
The first term that I noted during the movie was Conductive Polymers. Conductive polymers are almost always organic meaning a large class of chemical compounds whose molecules contain carbon. These polymers have extended delocalized bonds which are bonds found in a molecule that do not belong to a single atom or covalent bond. They are conjugated systems of double bonds and in a aromatic systems. The conjugated systems are atoms covalently bonded with alternating single and double bonds. When the electrons are removed or added into the valence bands the electrical conductivity increases. The conductive polymer has a low conductivity until the electron is removed from the valence band called (p-doping) or (n-doping) until it becomes more conductive. The movement of the charges is what is responsible for electrical conductivity. These polymers are plastic which are organic polymers and with mechanical properties such as flexibility and elasticity.
Dialysis tubing is made from regenerated cellulose or cellophane, and is used in clinical circumstances to ensure that molecule have a filtered flow, and that larger solute molecules do not enter the dialysis tubing (Alberts, 2002). Like a cell membrane, dialysis tubing has a semi-permeable membrane, which allows small molecule to permeate through the membrane. Thus, the dialysis tubing mimics the diffusion and osmosis processes of the cell membrane (Alberts, 2002). Although the dialysis tubing has a semi-permeable membrane, which mimics a cell, its structure is different. The me...
All polymer host has some major advantages for which their application in electrochemical devices are still continuing. Also these polymer have some disadvantages and to improve the
Graphene has received great mass media coverage since Geim and Novoselov published their foundlings about monocrystalline graphitic films in 2004, which won them the Nobel Prize in Physics in 2010. (Novoselov et al, 2004) It has been described as the wonder substance or super material by the mass media, not only because it is the thinnest material ever known and the strongest ever measured, but also due to its excellent electrical, thermal, mechanical, electronic, and optical properties. It has high specific surface area, high chemical stability, high optical transmittance, high elasticity, high porosity, tunable band gap, and ease of chemical functionalization which helps in tuning its properties (Geim et al, 2007) Moreover, graphene has a multitude of amazing properties such as half-integer room-temperature quantum Hall effect (Novoselov et al, 2007), long-range ballistic transport with almost ten times greater electron mobility than that of silicon, and availability of charge carriers that behave as massless relativistic quasi particle, known as Dirac fermions. (Geim et al, 2007) The outstanding electrical conductivity and the transparency and flexibility of graphene-based material have led to research and development of some future technologies, such as flexible and wearable electronics. In addition, graphene can also be used for efficient energy storage materials, polymer composites, and transparent electrodes. (Geim et al, 2007) This paper presents a
The electrodialysis operation was carried out on a laboratory stack “PCCell ED 64 002” supplied by PCA-Polymerchemie Altmeier GmbH and PCCell GmbH, Heusweiler, Germany. As shown in Fig 3, ED cell is packed with ion exchange membranes (cation and anion), spacers and a pair of electrodes (anode and cathode). Both electrodes are made of Pt/Ir - coated Titanium. The membranes and spacers are stacked between the two electrode-end blocks. Plastic separators are placed between the membranes to form the flow paths of the dilute and concentrate streams. These spacers are designed to minimize boundary layer effects and are arranged in the stack so that all the dilute and concentrate streams are manifolded separately. In this way a repeating section called a cell pair is formed; it consists of a cation exchange membrane, a dilute flow spacer, an anion-exchange membrane, and a concentrate flow spacer. In this work, experiments were carried out by this stack equipped with three cation exchange membranes (CEM) and two anion exchange membranes (AEM).
In addition, there’s another entrance on the opposite side of the circuit that oxygen flows into, creating a water molecule, or H2O (hydrogenenergy.com). Hydroelectric power comes when water runs through a dam. The floor of the dam rises, taking the water with it. When the water is higher up, it transforms more energy to gravitational, creating falling water. The falling water falls through the turbines and creates electrical energy that runs through transmission lines to buildings and homes. Hydrogen fuel cells are put into battery form through a very simple circuit, which splits the hydrogen atom apart and creates electrical energy from the electron while completing the circuit. Fuel cells are very reliable, and have a high energy efficiency. Sadly, the cost is very high to install circuits, but their very easy and cheap to maintain. It works in all locations, since anywhere on the globe has oxygen and hydrogen atoms in the air(fuelcelltoday.com). While that still costs a lot, it can provide more energy to buildings and houses than fuel cells can. This is because hydroelectric power comes in larger quantities, since it only is sent when the dam rises, taking water with it. While this cannot power cars, it is a lot cheaper to buy, since maintenance is cheap. Some could argue that these two sources are some of most expensive
This quite novel material has progressed rapidly toward scaling up production of 30 in graphene membranes (Bae et al., 2010). The tiny thickness of graphene, i.e. one atomic layer, and its enhanced tensile strength (Lu and Huang, 2009), could allow accelerated water transport, low pressure supplies, and flexible array of operating conditions, and also, could be considered among the potential advantages of graphene compared to current RO membranes.
A microbial fuel cell (MFC) or biological fuel cell is a bio-electrochemical system that drives a current by using bacteria, and mimicking bacterial interactions found in nature. (2)
Advanced materials are classified as completely new materials which have some specific properties and functions. These advance materials have large utility in daily life, hospitality, industries, sports etc. currently scientists and researchers are working and studying their specific functions etc. some great examples of these materials include thin membranes, Composite and hybrid materials, polymers, ceramic and radiation shielding composites; lightweight and nanocomposite, Metals and alloys, Ceramics, Smart materials (Photo-, thermo-, piezo-, tribo- and electro-chromic materials. Thin film coatings. Now a day thermoelectric materials have significant value in scientific world it include temperature measuring devices in furnace, energy harvestings and advance sensor etc. and many more. Here we discuss about thermoelectric and materials used in it.
In an age where our dependence on fossil fuels and other expendable resources is dramatically increasing as our supply is decreasing, it is imperative that new forms of energy arise. Although it is still in very early stages, it is fundamentally plausible that hydrogen could become a major fuel source in cars. For example, Honda has already released five hydrogen fuel cell cars.
Hydrogen would be one of the easiest sources of renewable energy to incorporate into our current energy infrastructure. Since hydrogen is a gas of normal temperature, it is possible to have it be used as a fuel in vehicles similar to current ones. For example, Hydrogen could be introduced into the vehicle as a gas, stored...
. Also, high temperature prevents the electrodes from reacting with carbon monoxide which eventually could lead to corrosion [Fuel Cell ...