Chapter 10 Boiling and Condensation10-20Water is boiled at a saturation (or boiling) temperature of Tsat= 120°C by a brass heating element whose temperature is not to exceed Ts= 125°C. The highest rate of steam production is to be determined.Assumptions1Steady operating conditions exist. 2Heat losses from the boiler are negligible. 3The boiling regime is nucleate boiling since ΔTTTs=−=−=°satC125 1205which is in the nucleate boiling range of 5 to 30°C for water. PropertiesThe properties of water at the saturation temperature of 120°C are (Tables 10-1 and A-9) ρσlvl====94341120 0550144....kg / mkg / mN/mPr33hfglpl=×⋅=⋅°−2203 100 232 10424433J/kgkg m / sC J/kgCμ.Ts=125°CWater120°CHeating elementAlso, 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. Csf=AnalysisAssuming nucleate boiling, the heat flux in this case can be determined from Rohsenow relation
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