###### Fundamentals of Heat and Mass Transfer - Solution Manual

1422 SOLVED PROBLEMS

Question: 10.35

## KNOWN: Copper sphere, 10 mm diameter, initially at a prescribed elevated temperature is quenched in a saturated (1 atm) water bath. FIND: The time for the sphere to cool (a) from Ti = 130 to 110°C and (b) from Ti = 550°C to 220°C . ASSUMPTIONS: (1) Sphere approximates lumped capacitance, (2) Water ...

ANALYSIS: Treating the sphere as a lumped capacita...
Question: 10.34

## KNOWN: Surface temperature and emissivity of strip steel. FIND: Heat flux across vapor blanket. ASSUMPTIONS: (1) Steady-state conditions, (2) Vapor/jet interface is at Tsat for p = 1 atm, (3) Negligible effect of jet and strip motion. PROPERTIES: Table A-6, Saturated water (100°C): ...

ANALYSIS: The heat flux is q_s^{\prime\prim...
Question: 10.31

## KNOWN: Inner and outer diameters, outer surface temperature and thermal conductivity of a tube. Saturation pressure of surrounding water and convection coefficient associated with gas flow through the tube. FIND: (a) Heat rate per unit tube length, (b) Mean temperature of gas flow through tube. ...

ANALYSIS: (a) The heat rate per unit length is [la...
Question: 10.29

## KNOWN: Horizontal, stainless steel bar submerged in water at 25°C. FIND: Heat rate per unit length of the bar. ASSUMPTIONS: (1) Steady-state conditions, (2) Film pool boiling, (3) Water at 1 atm. PROPERTIES: Table A-6, Water, liquid (1 atm, Tsat = 100°C): ρl = 957.9 kg/m3, hfg = 2257 kJ/kg; Table ...

ANALYSIS: The heat rate per unit length is ...
Question: 10.28

## KNOWN: Electrical conductor with prescribed surface temperature immersed in water. FIND: (a) Power dissipation per unit length, q′s and (b) Compute and plot q′s as a function of surface temperature 250 ≤ Ts ≤ 650°C for conductor diameters of 1.5, 2.0, and 2.5 mm; separately plot the percentage ...

ANALYSIS: (a) The heat rate per unit length due to...
Question: 10.32

## KNOWN: Cylinder of 120 mm diameter at 1000K quenched in saturated water at 1 atm FIND: Describe the quenching process and estimate the maximum heat removal rate per unit length during cooling. ASSUMPTIONS: Water exposed to 1 atm pressure, Tsat = 100°C. ...

ANALYSIS: At the start of the quenching process, t...
Question: 10.27

## KNOWN: Steel bar upon removal from a furnace immersed in water bath. FIND: Initial heat transfer rate from bar. ASSUMPTIONS: (1) Uniform bar surface temperature, (2) Film pool boiling conditions. PROPERTIES: Table A-6, Water, liquid (1 atm, Tsat = 100°C): ρl = 957.9 kg/m³, hfg = 2257 kJ/kg; Table ...

ANALYSIS: The total heat transfer rate from the ba...
Question: 10.26

## KNOWN: A sphere (aluminum alloy 2024) with a uniform temperature of 500°C and emissivity of 0.25 is suddenly immersed in a saturated water bath maintained at atmospheric pressure. FIND: (a) The total heat transfer coefficient for the initial condition; fraction of the total coefficient contributed ...

ANALYSIS: (a) For the initial condition with [late...
Question: 10.24

## KNOWN: Operating conditions of apparatus used to determine surface boiling characteristics. FIND: (a) Nucleate boiling coefficient for special coating, (b) Surface temperature as a function of heat flux; apparatus temperatures for a prescribed heat flux; applicability of nucleate boiling ...

ANALYSIS: (a) The coefficient \mathrm C_{\m...