Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
8th Edition
ISBN: 9781305387102
Author: Kreith, Frank; Manglik, Raj M.
Publisher: Cengage Learning
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Chapter 2, Problem 2.16P
To determine
The increase in heat transfer.
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In boiling water at 1 atm pressure outside a stainless-steel tube with a surface temperature of 410F, the heat-transfer coefficient h in the absence of radiation is 32 Btu/h*ft^2*F. If the emissivity of the stainless steel is 0.8, will radiation significantly augment the rate of boiling (e.g., by more than 5 percent)? Assume that the vapor film is transparent to radiation and the boiling liquid is opaque.
Water is to be boiled at atmospheric pressure in a polished copper pan by means of an electric heater. The diameter of the pan is 0.51 m and is kept at 111 deg C. What is the power required to boil the water? Tsat = 100°C; Properties of water at 100°C: Density, ρl= 961 kg/m3; Kinematic viscosity, ν = 0.293x10-6 m2/s; Prandtl Number, Pr = 1.740; Specific heat, Cpl = 4216 J/kg.K; Dynamic viscosity, μ = ρ × ν = 961 × 0.293 × 10-6 = 281.57 x10-6 Ns/m2; hfg = 2256.9 kJ/kg; ρv = 0.597 kg/m3; σ = 0.0588 N/m; Csf=0.013; n=1;
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A copper rod, an aluminum rod, and a brass, each 6.00 m length and 1.00 cm diameter, are placed end to end with the aluminum rod between the other two. The free end of the copper rod is maintained at water’s boiling point, and the free end of the brass rod is maintained at water’s freezing point. If T1 and T2 are steady-state temperature copper-aluminum junction and aluminum-brass junction respectively. Where TC is temp at freezing point of water and TH is temp at boiling point of water. Show that the steady-state temperature for (a) the aluminum-brass junction is:
Chapter 2 Solutions
Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
Ch. 2 - A plane wall, 7.5 cm thick, generates heat...Ch. 2 -
2.2 A small dam, which is idealized by a large...Ch. 2 - 2.3 The shield of a nuclear reactor is idealized...Ch. 2 - A plane wall 15 cm thick has a thermal...Ch. 2 - 2.5 Derive an expression for the temperature...Ch. 2 - A plane wall of thickness 2L has internal heat...Ch. 2 - 2.7 A very thin silicon chip is bonded to a 6-mm...Ch. 2 - 2.9 In a large chemical factory, hot gases at 2273...Ch. 2 - 2.14 Calculate the rate of heat loss per foot and...Ch. 2 - 2.15 Suppose that a pipe carrying a hot fluid with...
Ch. 2 - Prob. 2.16PCh. 2 - Estimate the rate of heat loss per unit length...Ch. 2 - The rate of heat flow per unit length q/L through...Ch. 2 - A 2.5-cm-OD, 2-cm-ID copper pipe carries liquid...Ch. 2 - A cylindrical liquid oxygen (LOX) tank has a...Ch. 2 - Show that the rate of heat conduction per unit...Ch. 2 - Derive an expression for the temperature...Ch. 2 - Heat is generated uniformly in the fuel rod of a...Ch. 2 - 2.29 In a cylindrical fuel rod of a nuclear...Ch. 2 - 2.30 An electrical heater capable of generating...Ch. 2 - A hollow sphere with inner and outer radii of R1...Ch. 2 - 2.34 Show that the temperature distribution in a...Ch. 2 -
2.38 The addition of aluminum fins has been...Ch. 2 - The tip of a soldering iron consists of a 0.6-cm-...Ch. 2 - One end of a 0.3-m-long steel rod is connected to...Ch. 2 - Both ends of a 0.6-cm copper U-shaped rod are...Ch. 2 - 2.42 A circumferential fin of rectangular cross...Ch. 2 - 2.43 A turbine blade 6.3 cm long, with...Ch. 2 - 2.44 To determine the thermal conductivity of a...Ch. 2 - 2.45 Heat is transferred from water to air through...Ch. 2 - 2.46 The wall of a liquid-to-gas heat exchanger...Ch. 2 - Prob. 2.47PCh. 2 - The handle of a ladle used for pouring molten lead...Ch. 2 - 2.50 Compare the rate of heat flow from the bottom...Ch. 2 - 2.51 Determine by means of a flux plot the...Ch. 2 - Prob. 2.52PCh. 2 - Determine the rate of heat transfer per meter...Ch. 2 - Prob. 2.54PCh. 2 - 2.55 A long, 1-cm-diameter electric copper cable...Ch. 2 - Prob. 2.56PCh. 2 - Prob. 2.57PCh. 2 - Prob. 2.58P
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- Kindly answer this question, T= 30 degreesarrow_forwardThe condensation process of vapors on the outside of horizontal tube banks is described by the equation below, NNU = 0.725 (g p² hfg Do³) μ Δt Ν κ At 45 C R-22 properties are: Density, p Dynamic viscosity, μ Latent heat, hfg Thermal conductivity, k where N tubes/row At = hfg AT = difference between wall surface & R-22 NNu Refrigerant - 22 condenser operating at 45 C cooled with water from cooling tower entering at 30 C and leaves at 36 C. The condenser is shell-tube type with copper tubes of 14 mm ID & 16 mm OD arranged with 3 tubes per row (N). a) Compute the convective heat transfer of R-22 in W/m²K. = 1,109 kg/m³ 0.00018 Pa s 160.9 kJ/kg 0.0779 W/m K (*50-45) = 5 C (*from sample problem #2 pipe wall temperature) diff. of temp between wall & fluid latent heat of condensation generally a function of (NR₂. Npr) D/ karrow_forwardAwnserarrow_forward
- Must solve all questions.arrow_forwardThe boiling temp of nitrogen at 1 atm is -196°C. The temp of liquid nitrogen in a tank open to the atmosphere at sea level will remain constant until it is depleted. Any heat transfer to the tank will result in the evaporation of some liquid nitrogen, which has a heat of vaporization of 198 kJ/kg and a density of 810 kg/m² at 1 atm. Consider a 3-m-diameter spherical tank that is initially filled with liquid nitrogen at 1 atm and -196°C. The tank is exposed to ambient air at 15°C, with a convection heat transfer coefficient of 35 W/m?-K. The temperature of the thin-shelled spherical tank is observed to be almost the same as the temperature of the nitrogen inside. Determine the rate of evaporation of the liquid nitrogen in the tank as a result of heat transfer N, vapor from the ambient air if the tank is (a) not insulated, (b) insulated with 5- T= 15°C cm thick fiberglass insulation (k=0.035 W/m-K) and (c) insulated with 2- cm thick super-insulation which has an effective thermal…arrow_forwardThe condensation process of vapors on the outside of horizontal tube banks is described by the equation below, NNU = 0.725 (gp² hfg Do³) μ Δt Ν k where N tubes/row At = hfg Density, p Dynamic viscosity, μ Latent heat, hfg Thermal conductivity, k AT = difference between wall surface & R-22 NNu 3 1,109 kg/m 0.00018 Pa s = Refrigerant - 22 condenser operating at 45 C cooled with water from cooling tower entering at 30 C and leaves at 36 C. The condenser is shell-tube type with copper tubes of 14 mm ID & 16 mm OD arranged with 3 tubes per row (N). a) Considering the results of sample problem #2 (fw = 6,909.4 W/m²K film coefficient at water side), compute the overall heat transfer coefficient based on outer surface area in W/m² K of a water-cooled shell-tube R-22 condenser. At 45 C R-22 properties are: 160.9 kJ/ kg 0.0779 W/m K (*50-45) = 5 C (*from sample problem #2 pipe wall temperature) diff. of temp between wall & fluid latent heat of condensation generally a function of (NR₂. Nor) D/ karrow_forward
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