A number of plants, engines and equipments require heat energy or other similar forms of energy in their operations and processes. Such facilities depend on a means of generating the required amount of energy on a continuous basis. For such systems, the heat is mostly generated by combusting or burning liquid or gaseous fuel in the presence of oxygen (in air). Such combustion or conversion of chemical energy to heat energy occurs in thermal units generally referred to as combustion chambers (Bonnick 2008). The energy of the fuel (mainly hydrocarbons) is released by igniting the fuel in the presence of air.
The released energy will then be used to achieve the required purposes. In gas turbines, for instance, the released energy is used in driving the blades of the generators (Stocker and Tertilt 2007). For automobiles, the energy is used in driving the engines (Bonnick 2008) and in water heaters, the fuel energy produces the energy required for heating (Derek 2007). One major consideration in the design, installation and operation of combustion chambers is efficiency in the conversion from chemical energy to the needed form of energy (Schock 1984, Derek 2007).
This is necessary in the view of the fact that system performance is an important index in the rating of systems. One way of determining performance or combustion efficiency is to examine and analyse the products of the combustion process vis-a-vis the amounts of the combustion air and fuel supplied (Derek 2007). This report is an attempt at presenting the efforts at determining the efficiency of a typical combustion chamber with a predetermined amount of fuel and combustion air (that is, air/fuel ratio). In particular, using a typical combustion chamber, this work intends to
? investigate the characteristic property of a stoichiometric and a fuel lean combustion ? determine the amount of the constituents of the flue gases (combustion products) with given amounts of air/fuel ratio. Principal among these by-products are oxygen and carbon dioxide. ? conduct an input-output heat balance on the combustion system ? to calculate, for the predetermined air/fuel ratios, the percentages of excess air and sensible heat loss due to combustion using the amount of the carbon dioxide present in the flue gases ? to compare the result of this experiment with the theoretical result predicted using the computer program FLAME
? to assess the efficiency of the combustion unit as a water heater and conclude on the effect of air factor on the unit’s efficiency Literature Review Combustion chamber works on the principles of thermodynamics(Rolle 2004). The law of conservation of energy becomes applicable in the conversion of the fuel energy to the desired heat energy (Derek 2007; Bonnick 2008). Based on this principle, the input-output heat balance can be easily computed for the combustion unit. Besides this, the principle of conservation of mass also holds (Rolle 2004).
This helps in establishing the mass input-mass output balance of the whole combustion process. Theoretically, once the stoichiometric compositions of the reacting chemicals are ascertained, the respective masses of the by products can easily be established using the balanced equation of the combustion reaction. Experimentally, the mass flow rates of the reacting chemicals can be determined. Using this as the total mass of the output products (based on the law of conservation of mass), the percentage compositions of the flue gas constituents especially, oxygen and carbon dioxide, can be determined (Derek 2007; Bonnick 2008).
Moreover, Derek (2007) made a case for a fuel-lean combustion in order to maintain a relatively high level of efficiency with combustion products that have a low tendency of causing environmental hazards. In other words, combustions whose amount of fuel is limited will give products that are rich in excess air and low in carbon monoxide (which constitutes environmental hazards). This is presented as an acceptable approach in combustion in the light of the recent ‘global climate change‘. References
Bonnick, A, 2008, Automotive Science and Mathematics, Elsevier Science and Technology Publishing, US. Derek, D, 2007, Lean combustion: technology and control, Academic Press, US. Rolle, KC, 2004, Thermodynamics and heat power, Pearson Education, US Schock, AHAJ, 1984, ‘A review of internal combustion engine combustion chamber process studies at NASA Lewis Research Center’, Joint Propulsion Conference, June 11-13, 1984. Stocker, B, & Tertilt, M, 2007, ‘Combustion Chamber’, United States Patent 7299634 available at www. FreePatentsOnline. com.Sample Essay of StudyFaq.com