Heat capacity combustion gases

Estimate the combustion temperature of an incinerator contaminated with hospital alcohol, 50% ethyl alcohol +50% water and solids (may treat all as water) by weight using 40% EA. To simplify the calculations, assume an average flue gas heat capacity for N2, CO2, and O2 of 0.26 and for H2O vapor of 0.5 Btu/(lb °F). 

Figure 6-17 illustrates a constant-volume calorimeter of a type that is often used to measure q for combustion reactions. A sample of the substance to be burned is placed inside the sealed calorimeter in the presence of excess oxygen gas. When the sample bums, energy flows from the chemicals to the calorimeter. As in a constant-pressure calorimeter, the calorimeter is well insulated from its surroundings, so all the heat released by the chemicals is absorbed by the calorimeter. The temperature change of the calorimeter, with the calorimeter s heat capacity, gives the amount of heat released in the reaction. 

CA 62, 12965(1965). Following is its abstract A criterion for unidimensional instability of detonation of gases is derived, taking into account the thermal effects of the reaction. Instability occurs when [(y -1)/ y](E/RT)[1 /(1 + cg/c) qU>l, where y is the heat capacity ratio, E is the energy of activation, Cg and c are the velocities of sound in the burned and unburned gases, resp, q is the ratio of thermal effect of combustion to the internal energy of the unburned gas, and M is the ratio of the burning rate to the velocity of sound in the unburned gas... 

W. Braker, A.L. Mossman, Matheson Gas Data Book, Matheson Gas Products, East Rutherford 1971, p. 301. Ihave left out some of the less interesting dimensions in this connection heat capacity (20.9°C) 2.625 J g 1 K 1 (Water 4.187 J g 1 K 1) dielectricity constant (20°C) 114 (Water=78.5) evaporation heat 28 kJ mol"1 evaporation entropy 190 J mol"1 K"1 spontaneous combustion temperature 538°C flash point -17.8°C regarding dielectricity constants, see R.C. Weast (ed.), Handbook ofChemistry and Physics, 66th Ed., CRC Press, Boca Raton, Florida 1986, E 40. However, under normal conditions (1 atm, 25°C), hydrogen cyanide is not a gas. 

Combustion products from a burner enter a gas turbine at 7.5 bar and 900°C and discharge at 1.2 bar. The turbine operates adiabatically with an efficiency of 80 percent. Assuming the combustion products to be an ideal-gas mixture with a heat capacity of 30 J mol-1 °C, what is the work output of the turbine per mole of gas, and what is the temperature of the gases discharging from the turbine ... 

Exhaust gas at 375°C and 1 bar from internal-combustion engines flows at the rate of 100 mol s-1 into a waste-heat boiler where saturated steam is generated at a pressure of 1,000 kPa. Water enters the boiler at 20°C (T0), and the exhaust gases leave at 200°C. The heat capacity of the exhaust gases is Cp/R = 3.34 + 1.12 x 10-3T, where T is in kelvins. The steam flows into an adiabatic turbine from which it exhausts at a pressure of 30 kPa. If the turbine efficiency r) is 75 percent,... 

The flammability limits of hydrocarbon-type fuels in oxygen and inert gas atmospheres are a function of the inert gas and any fuel or oxygen in excess of that required by the stoichiometry of the combustion process. In systems where fuel content is fixed, inert material having a high heat capacity will be more effective at flame suppression than inert material having a low heat capacity. 

Whereby y is the ratio of the specific heat capacities of the gas mixture, R is the gas constant, Tc is the temperature (K) in the combustion chamber and M is the average molecular weight (kg mol ) of the formed combustion gases ... 

The retarding effect of HX, X, RX introduced into the flame may be of either physical or chemical nature (in either case, the residue R in RX is an extra fuel source). In the first case, the flame retardant reduces the oxygen concentration in the combustible mixture in the flame reaction zone by mere dilution, in the same way as added carbon dioxide or nitrogen. The heat capacity of the resultant mixture determines the amount of heat drained off for its heating. In the second case, the flame retardant directly participates in the flame reactions and affects the complex combustion process kinetics. The HX molecule is the main inhibiting particle. When RX is released into the gas phase of fuel-rich flames, HX is formed predominantly via RX -b H HX + RX, when Xj is released, HX is formed via X + H HX + X. 

In the theoretical analysis of shock instability, shock waves that are not too strong are presumed to propagate axially back and forth in a cylindrical chamber, bouncing off a planar combustion zone at one end and a short choked nozzle at the other [101], [102]. The one-dimensional, time-dependent conservation equations for an inviscid ideal gas with constant heat capacities are expanded about a uniform state having constant pressure p and constant velocity v in the axial (z) direction. Since nonlinear effects are addressed, the expansion is carried to second order in a small parameter e that measures the shock strength discontinuities are permitted across the normal shock, but the shock remains isentropic to this order of approximation. Boundary conditions at the propellant surface (z = 0) and at the... 

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