| OCR Text |
Show conv (L,, Convective transfer from zone to waterwall WW conv Q Convective transfer from zone to refractory ref Qchem Chemical heat release from fuel consumption within zone mhj Sensible energy carried out of the zone, specified by the zone temperature mhj_j Sensible energy entering the zone from the zone immediately upstream In Case II, Figure 4(b), additional detail is added in the form of recirculation flows and radiative transfer between zones. These new fluxes are described by: Q. Heat carried from zone to the zone upstream of it by J recirculation reci re Q.,. 'j+l Hiemamte dicaatrerliye d dionwtnos trzeoanme by recirculation from the zone ra d Q._ Gas-to-gas net radiative contribution to the zone from J n surrounding zones (n = ±1, ±2, ±3) Thus for Case I, the steady-state energy balance is given by: y Q. = mh . - mh • , + 0 „ - Qrad - Qra? - QCOnV - <£°"v = 0 U) Zrf I J J~l chem vww wref ww vref (2) And for Case II it is: n=-3 The solution algorithm requires in each case that the energy flow terms are all cast in terms of one unknown - the effective temperature of the zone. The form of the set of nonlinear equations for radiative interchange in this system suggested recasting them as an electrical network. The schematic for such a network is shown in Figure 5. The radiosities and blackbody emissive powers are represented by node potentials, while heat transfer rates are analogous to electrical currents. The conductance associated with each resistor in the circuit is specified by an appropriate equation. Summing the currents into each node produces three independent equations. If all but 5.5.6 |
