The heat flux that is applied to one face of a plane wall is
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Introduction to Heat Transfer 6th Edition (Wiley Editor's Choice Edition)
- A plane wall 15 cm thick has a thermal conductivity given by the relation k=2.0+0.0005T[W/mK] where T is in kelvin. If one surface of this wall is maintained at 150C and the other at 50C, determine the rate of heat transfer per square meter. Sketch the temperature distribution through the wall.arrow_forward2.2 A small dam, which is idealized by a large slab 1.2 m thick, is to be completely poured in a short Period of time. The hydration of the concrete results in the equivalent of a distributed source of constant strength of 100 W/m3. If both dam surfaces are at 16°C, determine the maximum temperature to which the concrete will be subjected, assuming steady-state conditions. The thermal conductivity of the wet concrete can be taken as 0.84 W/m K.arrow_forwardA steel tube with a thermal conductivity of 45 W/m.K carries a fluid at 200°C, with a convection heat transfer coefficient of 210 W/m2./K. The tube has an external diameter of 5 cm, a wall thickness of 1 cm and a length of 2 m. The ambient air and surroundings are at 25°C, with a convection heat transfer coefficient of 25 W/m2.K. Neglecting the effects of radiation, determine: 1) resistance by conduction through the pipe wall 2) the convection resistance inside the tube 3) The total heat transfer rate 4) The temperature of the outer surface of the tube Upload resolution images, please.arrow_forward
- The thermal conductivities of human tissues vary greatly. “Fat” and “skin” have conductivities of approximately 0.200 W /m 0K and 0.0200 W /m 0K, respectively, while other “tissues” inside the body have conductivities of approximately 0.500 W /m 0 Assume that between the core region of the body and the skin surface lies a “skin” layer of 1.00mm, a “fat” layer of 0.500 cm., and 3.20 cm. layer of other “tissues”. Find the rate of energy loss when the core temperature is 37.00C and the exterior temperature is 0.000 Assume a body area of 2.00 m2. (Both a protective layer of clothing and an insulating layer of unmoving air are absent).arrow_forwardAn electric cable consists of an inner core and an outer protection layer. The shape of the cable can be approximated as a cylinder. The diameter of the inner core is D1 = 1.6 cm and the total diameter of the cable is D2 = 2 cm. The thermal conductivities for the cable inner core and outer layer are k = 50 W/m·K and k = 0.1 W/m·K, respectively. The electric current in the inner core causes a volumetric thermal energy generation rate of q ̇ = 10^(6) W/(m^(3)) . The cable is placed in an air crossflow of u∞ = 2 m/s and T∞ = 300 K. The air in the film around the cylinder has a kinematiccrossflow of u∞ = 2 m/s and T∞ = 300 K. The air in the film around the cylinder has a kinematic viscosity of ν = 2 × 10^(−5 )(m^2)/s, thermal conductivity of kf = 0.025 W/m · K, and Prandtl number of Pr=0.7. Assume one-dimensional and steady-state conduction heat transfer along the radial direction of the cable cross section. Perform heat transfer analysis for a section of the cable with length L = 10 cm.…arrow_forwardOver the outside part of the room window, the wind is blowing with a speed of 10 m/sec. Due to this wind motion, the temperature on the outer surface of the window is 5 degrees lower than the room temperature. Determine the convective heat flux if the wind temperature is 10 C with a heat transfer coefficient of 10 W/(mK). Accept the temperature inside the room as 25 C. A) 200 W B) 100 W C) 200 W/(m^2) D) 100 W/(m^2) E) Not sufficient informationarrow_forward
- A steel duct whose internal diameter is 5.0 cm, and external diameter is 7.6 cm and thermal conductivity is: k = 15.0 (W/(m ºC)) is covered with an insulating material whose thickness is 2.0 cm and of thermal conductivity k = 0.2 (W/(m ºC)). A hot gas flows through the interior of the duct at a temperature of 330.0 ºC that generates a heat transfer coefficient by forced convection h=400.0 (W/(m^2 · ºC)). The outer surface of the insulating layer is exposed to air whose temperature is 30.0 ºC with forced convection heat transfer surface h = 60.0 (W/(m^2 · °C)). As a process engineer and in charge of company operations, you have been asked to: i. Determine the heat loss experienced by the pipe along 10.0 m.ii. The temperature drops that are generated in the different thermal resistances of the system. That is, on the air side, the duct wall and on the hot gas side.arrow_forwardIndirect Cooling With Liquid Nitrogen. You are designing a system to cool an insulated silver plate of dimensions 2.00 cm × 2.00 cm × 0.60 cm. One end of a thermally insulated copper wire (diameter D = 2.70 mm and length L = 18.0 cm) is dipped into a vat of liquid nitrogen (T = 77.2 K), and the other end is attached to the bottom of the silver plate.(a) If the silver plate starts at room temperature (65.0 °F), what is the initial rate of heat flow between the plate and the liquid nitrogen reservoir?(b) Assuming the rate of heat flow calculated in part (a), estimate the temperature of the silver plate after 30.0 seconds.arrow_forwardIndirect Cooling With Liquid Nitrogen. You are designing a system to cool an insulated silver plate of dimensions 2.00 cm × 2.00 cm x 0.40 cm. One end of a thermally insulated copper wire (diameter D = 2.70 mm and length L = 12.0 cm) is dipped into a vat of liquid nitrogen (T = 77.2 K), and the other end is attached to the bottom of the silver plate. (a) If the silver plate starts at room temperature (73.0°F), what is the initial rate of heat flow between the plate and the liquid nitrogen reservoir? (b) Assuming the rate of heat flow calculated in part (a), estimate the temperature of the silver plate after 30.0 seconds.arrow_forward
- Steam at T∞ 1 = 320°C flows in a cast iron pipe (k = 80 W/m · °C) whose inner and outer diameters are D1 = 5 cm and D2 = 5.5 cm, respectively (Figure Q2b). The pipe is covered with 3-cm-thick glass wool insulation with k = 0.05 W/m · °C. Heat is lost to the surroundings at T2 = 5°C by natural convection and radiation, with a combined heat transfer coefficient of h2 = 18 W/m2 · °C. Taking the heat transfer coefficient inside the pipe to be h1= 60 W/m2 · °C, determine; i) the rate of heat loss from the steam per unit length of the pipe; and ii) the temperature drops across the pipe shell and the insulation.arrow_forward10 hot rods (L = 5 m and d = 2 cm) are buried in the ground parallel to each other each rod is 10 cm apart and at a depth 3 m from the ground surface. The thermal conductivity of the soil is 0.6 W/m K. If the surface temperature of the rods and the ground are 600 K and 30 °C, respectively. Draw the figure and determine the rate of heat transfer from the fuel rods to the atmosphere through the soilarrow_forwardSteam at T1 = 320°C and h1 = 60 W/m2·°C flows in a cast iron pipe (k = 80 W/m·°C). The inner and outer diameters are D1 = 5 cm and D2 = 5.5 cm, respectively. The insulation thickness is 3-cm-glass wool insulation with k= 0.05 W/m · °C. The temp. of the surroundings at T2 = 5°C and heat transfer coefficient of h2=18 W/m2·°C. Determine 1. Heat loss from the steam per unit length of the pipe. 2. Determine the temperature at the surfaces of the pipe and the insulation.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning