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Show r a, _3 (15) CD = a. + -±- + - V D ' Re Re2 where a,=1.222, a2, =-3.889 and a3=29.17 for Reynolds number less than 100. 2.3.1 Heat and Mass Transfer Calculations The heat and mass transfer from/to the oil droplets are described in a sequence of three laws. The first law accounts for inert heating of the droplet, and the second law accounts for droplet boiling. The third law includes the effects of droplet vaporization. The equations relating to these three governing laws may be viewed directly from the Fluent Users Manual (1999). The heat lost or gained by the particle as it traverses through each computational cell appears as a source or sink of heat in the subsequent calculations of the continuous phase energy equation. 2.4 NOx PRODUCTION MECHANISMS AND TRANSPORT There are four primary sources/mechanisms of NOx production in an oil fired glass melting furnace; viz., fuel NOx (reaction mechanism Eq.18) coming from the chemically bound nitrogen compounds with in the fuel (for details please refer to Smoot et al, 1998; Carvalho et al, 1990), prompt N0X (Eq. 17) is produced by high speed reactions at the flame front, thermal NOx (Eq. 16) from the reaction of nitrogen and oxygen in furnace gases which predominates, and the other source of N O x is from the dissolution of sodium or potassium nitrate which is added to the glass batch to act as a refining or oxidizing agent (Scmalhorst and Ernas, 1995). The production of a predominant source of N O x (thermal N O x), however, can be explained using the Zeldovich mechanism: Thermal NOr N+02-*K20+NO N+OH^Ki H + NO Prompt NOz CH + N:^>HCN + NO N+0:^>0 + NO HCN+OH -+CN + H:0 CN + N:^HCN + NH (17) HCN + N-*N2 + ... |