Two-Phase Fluid Flow Energy Balance

Liquid enters the superheater and begins boiling within a short distance of the entrance. The boiling (or two-phase) regime is where both the vapor and liquid phases are present. The two phases remain at a constant temperature until all the liquid is vaporized. An assumption must be made about this regime. Boiling is a turbulent process, especially in 

A shell balance can be written for the two-phase regime in terms of /, the weight fraction of vapor. It is defined as 

The reference state of the fluid is defined to be saturated liquid. The two-phase energy balance is 

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