Contents Abstract Nomenclature 1 Introduction 1.1 Motivation 1.2 Literature review 1.3 NOx formation mechanisms...........................................................................3 1.4 NOx reducing techniques..............................................................................5 1.4.1 Staged combustion..............................................................................5 1.4.2 Partially premixed flames...............................................................6 1.4.3 Flue gas recirculation.......................................................................8 1.4.4 Catalytic combustion...................................................................11 1.5 Computational fluid dynamic.........................................................................15 …show more content…
1.5.1 Governing equations of fluid flow and heat transfer.......................15 1.5.2 Generalized conservation equation...............................................17 1.5.3 Computation of turbulent flow.......................................................18 1.5.4 Modeling of swirl flow.................................................................22 1.5.5 Modeling reacting …show more content…
This contrary pressure gradient will create a backflow, referred to as central toroidal recirculation zone (CTRZ). The degree of swirl usually is characterized by a swirl number S, given by [9]: Where Gθ is the axial flux of swirl momentum, x G is the axial flux of the axial momentum and r is a characteristic radius such as the burner radius or the swirler radius. Typical profiles of axial and swirl velocity for a strong swirling flow (S>0.6) are shown in Figure 11 Figure 11: Flow recirculation in a strong swirling flow [3] Catalytic combustion The recent years catalytic combustion has proven to be one of the most promising NOx reducing techniques (see Figure 12). In catalytic combustion the fuel energy is converted into heat at a lower temperature than in ordinary combustion, thus reducing production of thermal NOx. In these systems the fuel reacts on the surface of the catalyst by a heterogeneous mechanism, where the catalyst is a ceramic or metal structure coated with noble metals. Because of the durability of the catalyst it is important to combust ultralean fuel-air mixtures with adiabatic combustion temperature below 1500 ˚C [19]. However, the observed reduction in NOx in catalytic combustors is much greater than that expected from the lower combustion temperature. The reaction on the catalytic surface apparently produces no NOx directly, although some NOx may be produced by homogeneous
Catching Fire: How Coooking Made us Human by Richard Wrangham is a fresh perspective on the evolution of humankind. Wrangham has made a concentrated effort to prove that humans have evolved particular adaptations, like bipedalism, due to the introduction of cooked foods into their diet. In his book, he is legitimately arguing that humans are the way they are because early on in human evolution, early man discovered fire, discovered the joys of cooked foods, and developed all sorts of fascinating traits still being utilized today.
The first thing in a firework is the oxidizing agent. These produce the Oxygen to burn the mixture. Oxidizers are usually nitrates, chlorates or perchlorates. The common oxidizers are nitrates. These are made up of a metal ion and the nitrate ion. I'll use potassium nitrate as an example. Nitrates only give up 1/3 of their oxygen. The resulting equation would look something like this:
...ese dangerously harmful gasses would be released into our atmosphere by all combustion engines. Although the catalytic converter when operating at its optimal temperature can break down over 95% percent of the harmful gasses produced by the engine it does not do a well at all when not at high temperatures. It takes about five miles of driving for most vehicles to reach a temperature at which the reactions will reach near completion, before this temperature the catalytic converter does practically nothing to convert these harmful gases. Some catalytic converters now have coils running from the engine to the catalytic converter to heat the catalytic converter to its optimal temperature soon after the engine has started to produce harmful gasses. With this improvement the catalytic converter can effectively reduce almost all of the carbon monoxide and nitrogen oxide.
This fluid is made up of 32.5% urea in 67.5% de-ionized water. This mixture is then injected into the exhaust stream using an advanced catalyst system. When DEF is released into the exhaust stream the hot exhaust causes the fluid to release ammonia which then breaks down the greenhouse harming gas of NOx into nitrogen and water. This fluid must be refilled at approximately every 10,000 miles (Voelcker).
However, under normal driving conditions an engine will encounter lean conditions when cruising on the highway (better mileage) and rich conditions when accelerating (better power). The lean condition results in oxide and harmful nitrogen production. Rich conditions result in carbon monoxide production. For this reason, catalytic converters are used on an engine’s exhaust. The catalyst material in a cat is a wire mesh or honeycomb.
A propellant is used in the military application and it is consists of oxidizer, fuel, plasticizer, curing agent and cross linkers. The commonly used oxidizer is ammonium perchlorate. But its combustion products are environmentally hazardous. Nowadays, ammonium nitrate is gaining great attraction in the field of propellant as a great oxidizer. Ammonium nitrate is an inorganic compound used as fertilizer, oxidizer and also for other applications. AN combined with fuel can be used in gas generators . The ammonium nitrate extracted from demilitarized rocket motors can be used as an oxidizing agent in the hydrothermal oxidation of organic wastes . It has seven phase transitions3.
The most probable equation to be proved correct is equation 2 because as Oxygen is needed for the reaction and the products are oxides, Oxygen cannot itself be released during combustion reactions, as indicated in the 'Oxford Dictionary of Chemistry'. Oxygen cannot be produced as a product, therefore we can disprove equation 1. Bibliography During my investigation I made use of the following resources: * Chemistry 1, B Ratcliff, H Eccles, D Johnson, J Nicholson, J Raffan * Hazcard references taken from the school network * The website http://dwb.unl.edu/chemistry/microscale/mscale16.html * Personal class notes * The Oxford Dictionary of Chemistry
“It was a pleasure to burn” this quote represents the opposite of our society because our society hates fire and thinks it is very dangerous. Fahrenheit 451 has a different society then our because our society has firefighters who stop fires and not start them, they burn books and our society Allows book and the houses in Fahrenheit 451 are fire proof and ours burn fast once it touches a flame.
...e is of the same sort as the exhaust temperature. Alteration of liquid hydrocarbons into gas must develop the burning process. Several doubts still stay on the expenses and the technical capability of the catalytic cracking process. If a division unit is necessary to separate the unreached part of the product stream from the gaseous hydrocarbons, the system will turn out to be more expensive. Though, if vaporization suffices, no additional apparatus will be needed.
Can be calculated dynamic viscosity ƞ from the kinematic viscosity μ and the density ρ according to equation (2.1.2).
The Olefins II Unit makes hydrocarbons from naphtha or natural gas using furnaces. After distillation, the p...
Equation: AB + CD AD + CB Combustion – Combustion reactions always involve oxygen and organic fuels to release energy. Equation: C_(x )
- the effect of Viscosity on liquid flow (turbulent/laminar) I have consulted my teachers for guidance and I have also looked very carefully into the "the Suggestions papers" which contain many possible investigations which have been done in the past. I opted to choose neither of them but many aspects I will be looking into in my investigation are similar to those in the papers.
Firstly, the gas turbine engine operation begins with the air intake process. As of all internal combustion engine, oxygen is required to support the combustion of the fuel and the source of oxygen is from the fresh air that is taken in. Initially, the fan is rotated by a driving shaft that is powered by the turbine of the engine. A negative or vacuum pressure at the intake side is then created by the rotating fan. Next, the surrounding air is drawn towards the inlet and causes it to flow into the gas turbine engine inlet (Cengel & Boles, 2011). At the same time, the pressure on the other side of the fan is increased as it is compressed at a lower pressure ratio and causes the air in the outlet side of the fan to move fu...
Some of the fluid flow, heat flow and particle flow problems are the most complex problems. It is difficult to find the analytic solution of these problems due to their extra-ordinary complexity. Scientists and engineers are facing this problem from decades and then they turned to the numerical methods. By developing increasingly better numerical schemes, researchers have been able to solve increasingly more complex flow problems [11]. The heat diffusion equations are used to describe the flow of heat. In chapter 2 we use Nodal Integral Method to solve the heat diffusi...