4. METHOD OF SOLUTION
A lumped parameter type of calculation is applied using averaged values for each sub-flow-area or subsurface. The same pressure drop is assumed to exist along each subchannel, and no net cross flow is allowed between them in any one axial step. Turbulent eddy, momentum exchange between adjacent subchannels is, however, calculated.
Four heat transfer modes are considered:
1) Surface to coolant convection.
2) Intersurface radiation exchange.
3) Intersurface conduction.
4) Surface to ambient heat loss.
Axial variation of physical properties and the redistribution of mass flow between subchannels can be accounted for by dividing the problem into a series of axial steps. The outflow properties of one step are used to compute the inflow properties of the next.