Hydrogen is a highly flammable gas and will burn at concentrations as low as 4% in air. The lower explosive limit (LEL) and upper explosive limit (UEL) are the two most common terminologies used to indicate the flammable levels for many fuels including hydrogen. Hydrogen is one of the least flammable materials at 4% but has a larger window (4–75% v/v H ) of flammability in comparison to natural gas, gasoline, propane, ethane, methane, propylene, etc. The flammability limit of hydrogen is seven times wider than methane. It is, therefore, critical for a hydrogen sensor to have a wider measurement range (1–99% v/v H2) for safety applications than most common fuels.
Oxygen and fuel combustion produces approximately 75% less flue gas than air fuel combustion and produces exhaust consisting primarily of CO2 and H2O. The justification for using oxy-fuel is to produce a CO2 rich flue gas ready for "The process of removing carbon from the atmosphere and depositing it in a reservoir." This has significant advantages over traditional air-fuel combustion. The mass and volume of the flue gas is reduced, less heat is lost in the flue gas. The size of the flue gas treatment equipment can be reduced.
CHAPTER 1 1.1 Chemical reactions with descriptions of starting raw materials Ethylbenzene will undergo catalytic dehydrogenation to produce styrene. The dehydrogenation reaction of ethylbenzene is an endothermic and reversible reaction. The optimum temperature for the reaction to occur is 590℃ to 650℃ and pressure of 200 mmHg or slightly above atmospheric pressure (Meyers, 2004). The required catalyst is potassium-promoted iron oxide in the presence of steam. The dehydrogenation process can be represented by the following chemical reaction: The main by-products produced from the dehydrogenation of ethylbenzene are benzene and toluene, which can be represented by the following chemical equations: The starting raw materials for
A mixture with a lower lambda value, say 0.97, has proportionately less air than fuel, and the mixture is slightly rich. The exhaust gas oxygen sensor is also called the lambda sensor, since it can be used to maintain the air-fuel ratio at lambda equal to 1, within very close limits. It can be installed in the exhaust manifold, where it measures the percentage of oxygen in the exhaust gases. A high percentage of oxygen may mean too little fuel is entering the engine, the mixture is too lean, and lambda is greater than 1. The sensor delivers this information to the ECU, which adjusts the mixture accordingly.
This drives the electrolysis of the H2O and/or CO2, splitting these oxides by removal of an oxygen atom, which is transported as an oxide ion across the electrolyte to the other electrode where the oxide ions recombine to produce gaseous oxygen. Fuels such as H2 and CO are thus produced, which can be reformed into other fuels such as methane or liquid hydrocarbons.
The substance undergoes a process called supercritical drying where the liquid is removed from the gel leaving the linked silica network without causing the material to collapse. As aerogel is made up of 95% to 99% air, it is very porous. Its pores are exceptionally minuscule preventing air particles from colliding with another and stopping gas phase conduction, and with that heat energy loss. To increase aerogel insulations effectiveness more materials are added, such as carbon. Aerogel insulation significantly reduces convection, conduction and radiation, which are the three procedures of heat transfer ("Low Energy House - What is Aerogel Insulation?").
This process uses to relatively cheap base starting materials benzene and propylene and this creates two much more valuable materials Phenol and Acetone. This is the most popular method to produce Acetone. It is produced by compressing Benzene and Propylene at 30 standard atmospheres at 250 degrees Celsius in the presence of a catalytic lewis acid. This is most likely to be Phosphoric acid as it is usually favoured over aluminium halides. The cumene is then oxidized in air which removes the tertiary benzylic hydrogen which forms a cumene radical.
Sulfur being hydrophobic in nature is removed by froth flotation process. Generally this process is used for the coal particle size less than 0.5mm. The carbonaceous mineral constituents of coal being hydrophilic in nature, can be made to preferentially attach to fine bubbles and float to the surface of a dilute slurry, where they can be removed, while in contrast the low carbonaceous inert minerals of the raw coal do not attach to the bubbles . Flotation reagent cost adds up to the processing cost which makes the flotation method more expensive than other physical methods. Yet, to remove inorganic materials viz.
CHEMISTRY DIGITAL ASSIGNMENT -2 NAME: SANJANAA S REG.NO: 15BIT0010 FACULTY NAME: RAJAGOPAL D SLOT: D1 INTRODUCTION: A Fuel cell is a device that converts the chemical energy into electricity by the chemical process. The chemical reaction majorly consists of the positively charged hydrogen ions with the oxygen and other oxidizing agents. Basically fuel cells are the cells which converts the chemically energy into electricity but it is very different from the batteries. Fuel cell requires a continuous supply of oxygen and the fuels whereas the batteries run over the chemically present or stored in the battery itself and generates an electromotive source. The first fuel cell was invented in the early 17th century and the first fuel cell came
The efficiency of a Peltier modules is only in between one-third and half of the conventional household devices . Thus the application is heavily restricted to area that cost is not important, system reliability and quietness during operation is the dominating factor. For thermoelectric generator, the conversion efficiency is below 20% . As there are more efficient products on the market, the high operating temperature (some require operating at above 700°C), the high material cost (some may cost more than 6000 UDS/kg) and the low output efficiency depending on the material chosen compel the growth of thermoelectric generator market . Consider that waste heat is a costless power source , the low efficiency of the thermoelectric generator  is no longer a significant