Thermodynamics HW Solutions 801

Thermodynamics HW Solutions 801 - Chapter 10 Boiling and...

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Chapter 10 Boiling and Condensation 10-20 Water is boiled at a saturation (or boiling) temperature of T sat = 120 ° C by a brass heating element whose temperature is not to exceed T s = 125 ° C. The highest rate of steam production is 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 125 120 5 which is in the nucleate boiling range of 5 to 30 ° C for water. Properties The properties of water at the saturation temperature of 120 ° C are (Tables 10-1 and A-9) ρ σ l v l = = = = 9434 112 0 0550 144 . . . . kg / m kg / m N/m Pr 3 3 h fg l pl =⋅ ° 2203 10 0 232 10 4244 3 3 J/kg kg m / s C J / k g C μ . T s =125 ° C Water 120 ° C Heating element Also, 0.0060 and n = 1.0 for the boiling of water on a brass surface (Table 10-3). Note that we expressed the properties in units specified under Eq. 10-2 in connection with their definitions in order to avoid unit manipulations. C sf = Analysis Assuming nucleate boiling, the heat flux in this case can be determined from Rohsenow relation
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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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