After heat treatment, the 2-cm-thick metal plates
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HEAT+MASS TRANSFER:FUND.+APPL.
- 7.43 Liquid sodium is to be heated from 500 K to 600 K by passing it at a flow rate of 5.0 kg/s through a 5-cmID tube whose surface is maintained at 620 K. What length of tube is required?arrow_forwardA 0.5-ampere current is flowing through a long electrically conducting cylindrical rod. The diameter of the rod is 6 mm, the electrical resistance of the rod is R = 2000 /m, and k =0.9 W/m K for the rod. The rod is encased in a 2-mm thick Pyrex tube and a 20°C liquid is flowing over the outer surface of the Pyrex tube. The convection heat transfer coefficient for the liquid h= 800 W/m2 . K. The interfacial conductance (contact resistance) at the interface between the rod and the Pyrex tube is h = 1200 W/m² - K. a) Compute the rate of heat generation in the rod and use it compute the volumetric rate of heat generation. b) Find the temperature drop across the interface between the outer surface of the rod and the inner surface of the Pyrex tube. c) Find the temperature at the center of the rod.arrow_forwardHeat Transfer (Third year) 2020- 2021 Homework 01-03-2021 By Dr. Basil Noori Merzah one-dimensional heat transfer and disregarding radiation, determine the rate of heat transfer through the wall. Q4/ Steam at T01-320°C flows in a cast iron pipe (k=80W/m. C) whose inner and outer diameters are D,=5cm, and D,-5.5cm, respectively. The pipe is covered with 3 cm thick glass wool insulation with k=0.05W/m. C. Heat is lost to the surroundings at T2-5°C by natural convection and radiation, with a combined heat transfer coefficient to be h,=18W/m."C. Taking the heat transfer coefficient inside the pipe to be 2 0 h,-60W/m. C, determine the rate of heat loss from the steam per unit length of the pipe. Also determine the temperature drops across the pipe shell and the insulation. Q5/ Determine the overall heat transfer coefficient U based on the outer surface of a D=2.5cm, and D =3.34 cm steel pipe (k=54.0W/m. C) for the following conditions: inside and outside heat transfer coefficients are…arrow_forward
- 2 (a) A short bronze cylinder of diameter 6 cm and length 12 cm is initially at 40°C and then plunged into a fluid at 200°C. The temperature at the centre of the cylinder is measured by a thermocouple to be 150°C after 5 minutes. What is the convective heat transfer coefficient between the cylinder and the fluid? The following properties of the bronze cylinder may be used: Thermal conductivity k = 26 W/m-K, density p = 8800 kg/m², and specific heat c = 420 J/kg-K. State and justify all assumptions made.arrow_forwardAn ordinary egg can be approximated as a 5.5-cm-diameter sphere whose properties are roughly k=0.6 W/m.oC and a=0.14 x 10-6 m2/s. The egg is initially at a uniform temperature of 8 oC and is dropped into boiling water at 97 oC. Taking the convection heat transfer coefficient to be h=1400 W/m2.oC, determine how long it will take for the center of the egg to reach 70oC.arrow_forwardA steam is flowing through a 5.7 m long of steel tube that has inner and outer radii of r, = 0.015 and r, 0,024 m, and a thermal conductivity of 0.14 W/m.K. The steam and the outer surface of the tube is maintained at constant temperature of 150 °C and the air = 25 °C, h = 0.35 W/m2.k) is surrounding the tube. To prevent the outer surface of the steel from the environmental conditions, a material that has a thermal conductivity of 0.014 W/m.k is wrapped over the outer surface of the steel. What is the maximum heat transfer from the steam to the air (W)? NOTE: Enter your answer. Answer Air Th Steam Steel Tr 111 Toarrow_forward
- (4) Oil with an average temperature of 80°C at an average flow velocity of 0,5 m/s, is flowing by pipeline with an inner diameter of 35 mm and a length of 15 m. Determine the heat transfer coefficient of the oil to the pipe wall, assuming that the average temperature of the pipe wall is 60°C. Oil properties are known, at 80°C: p=840 kg/m³, "c,=1,926 kJ/(kg-K), n=0,233 Pa-s, 2=0,179 W/(m-K).arrow_forward4-38 Carbon steel balls (p = 7833 kg/m2, k = 54 W/m K, c = 0.465 kJ/kg°C, and a 1.474 - 10-6 m2/s) 8 mm in diameter are annealed by heating them first to 900°C in a furnace and then page 300 allowing them to cool slowly to 100°C in ambient air at 35°C. If the average heat transfer coefficient is 75 W/m2-K, determine how long the annealing process will take. If 2500 balls are to be annealed per hour, determine the total rate of heat transfer from the balls to the ambient air. FIGURE P4-38 Air, 35°C Furnace Steel ball 100C 900°Carrow_forwardA 30-cm-radius metallic sphere is having thermal conductivity of k = 100. overall density of W 7 mk p = 1500- kg m² and heat capacity of C₂ = 3000 The sphere is initially at a uniform temperature of kgk CO T₁ = 20°C and is dropped into boiling water at T = 90°C. The convective heat transfer coefficient is assumed to be only h = 50; W m²K Using lump model, compute the temperature of the sphere after t = 1200 seconds. In solving this problem, please use and show the following steps (do not use EES) 1. Compute the volume and surface area 2. Compute the characteristic length Lc = k p Cp h Lc 4. Compute the Biot number Bi k 5. Calculate the Fourier number Fo= (at)/Lc² 6. Calculate the excess temperature using 0 = exp(-Bi * Fo) T-Too 7. Compute the target temperature T using 0 = Ti-Too 3. Compute the diffusivity a = = the sphere Vol Vol As == 3 r³ and А¸ = 4πr²arrow_forward
- What is the physical significance of the Fourier number? Will the Fourier number for a specified heat transfer problem double when the time is doubled?arrow_forwardIn a manufacturing facility, 2-in-diameter brassballs (k = 64.1 Btu/h·ft·°F, r = 532 lbm/ft3, and cp =0.092 Btu/lbm·°F) initially at 250°F are quenched in a waterbath at 120°F for a period of 2 min at a rate of 120 ballsper minute. If the convection heat transfer coefficient is42 Btu/h·ft2·°F, determine (a) the temperature of the balls afterquenching and (b) the rate at which heat needs to be removedfrom the water in order to keep its temperature constant at120°F.arrow_forward43% uo 7:52 * ZAIN IQ I. sheet No.3.pdf Homework 01-03 -2021 one-dimensional heat transfer and disregarding radiation, determine the rate of heat transfer through the wall. Q4/ Steam at Te1-320°C flows in a cast iron pipe (k=80W/m.°C) whose inner and outer diameters are D =5cm, and D=5.5cm, respectively. The pipe is covered with 3 cm thick glass wool insulation with k=0.05W/m.°C. Heat is lost to the surroundings at T02=5°C_by natural convection and radiation, with a combined heat transfer coefficient to be h,=18W/m.C. Taking the heat transfer coefficient inside the pipe to be h,=60W/m.C, determine the rate of heat loss from the steam per unit length of the pipe. Also determine the temperature drops across the pipe shell and the insulation. 05/ Determine the overall heat transfer coefficient U based on the outer surface of a D=2.5cm, and D=3.34 cm steel pipe (k=54.0W/m.°C) for the following conditions: inside and outside heat transfer coefficients are 1200W/m."C. and 2000W/m."C…arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning