Thermodynamics HW Solutions 809

Thermodynamics HW Solutions 809 - Chapter 10 Boiling and...

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Chapter 10 Boiling and Condensation 10-25 Water is boiled at a temperature of T sat = 150 ° C by hot gases flowing through a mechanically polished stainless steel pipe submerged in water whose outer surface temperature is maintained at T s = 165 ° C. The rate of heat transfer to the water, the rate of evaporation, the ratio of critical heat flux to current heat flux, and the pipe surface temperature at critical heat flux conditions are to be determined. Assumptions 1 Steady operating conditions exist. 2 Heat losses from the boiler are negligible. 3 The boiling regime is nucleate boiling since Δ TTT s = = = ° sat C 165 150 15 which is in the nucleate boiling range of 5 to 30 ° C for water. Properties The properties of water at the saturation temperature of 150 ° C are (Tables 10-1 and A-9) ρ σ l v l = = = = 9166 255 0 0488 116 . . . . kg / m kg / m N/m Pr 3 3 h fg l pl =⋅ ° 2114 10 0183 10 4311 3 3 J/kg kg m / s C J / k g C μ . Also, 0.0130 and n = 1.0 for the boiling of water on a mechanically polished stainless steel surface (Table 10-3). Note that we expressed the properties in units specified under Eq. 10-2 in
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This note was uploaded on 01/24/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.

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