3. A 2 m long cylindrical shell with variable conductivity (k (T) ko (3+ (T2/2) is...
2-157 A long electrical resistance wire of radius r.-0.25 cm has a thermal conductivity kwire-15 W/m-K. Heat is generated uniformly in the wire as a result of resistance heating at a constant rate of 0.5 W/cm3. The wire is covered with polyethylene insulation with a thickness of 0.25 cm and thermal conductivity of ks 0.4 W/m K. The outer surface of the insulation is subjected to free convection in air at 20°C and a convection heat transfer coefficient of 2...
A long cylindrical rod of diameter 220 mm with thermal conductivity 0.5 W/m-K expe riences uniform volumetric heat generation of 25,000 W/m3. The rod is encapsulated by a circular sleeve having 7 W/m K. The outer surface of the sleeve is exposed to cross flow of air at 25°C with a convection coefficient of 25 W/m2-K. Find the temperature at the interface between the rod and sleeve, and on the outer surface. an outer diameter of 410 mm and thermal...
Problem 1. (25%) The temperature on the inside surface of a CYLINDRICAL tank is T.(11) = 100°C under steady state conditions. The temperature outside the tank, T2(2), needs to be determined. The inner radius is 1 m and the outer radius is 1.3 m, and the tank material has a conductivity of k = 15 W/m. K. ONLY CONVECTION on the outer surface has to be considered. The ambient temperature is To = 25°C and the convection heat transfer coefficient...
Consider a 4 m high, 6 m wide and 0.17 m thick wall whose thermal conductivity is k = 0.8 W/m.oC. On a certain day, the temperatures of the inner and the outer medium close to the wall are measured to be 14oC and 6oC, respectively. Both inner and outer surfaces are subjected to convection heat transfer. Assume that the convection heat transfer coefficient is the same for the two surfaces h = 5 W/m2 ∙ °C. 1. Draw the...
Problem 2: Consider a large plane slab of semi-thickness L = 0.3 m, thermal conductivity k = 2.5 W/m K and surface area A = 20.0 m². Both sides of the slab is maintained at a constant wall temperature of 358°K while it is subjected to a uniform but constant heat flux of 950.0 W/m2 Evaluate the temperature distribution/profile within the wall. Calculate the heat flux and temperature at location x = 0.1m. Problem 3: Consider a 10.0 m long...
Consider a rectangular bar of thermal conductivity k W/m-K and
total length 2L, as shown in the figure, is connected to a hot
surface that is at a temperature T1. The connection between the bar
and the surface is imperfect and results in a thermal contact
resistance of R’’ m2-K/W. The width of the rod into the depth of
the paper is W meters and the thickness of the rod is t meters. The
first section of the rod of...
Question You are studying heat transfer through a spherical shell container with a thermal conductivity k. The inner and outer radii are identified as a and b, respectively. The inside surface of the shell is exposed to a constant heat flux in the outward direction. The outside surface temperature of the container is measured at Note that only the variables values provided in the problem statement are known. Assume steady one-dimensional radial heat transfer a. Give the mathematical formulation of...
Problem 3 (30): Steam at Too,1 340 °C flows in a cast iron pipe [k- 80 W/m.°C] whose inner and outer diameter are Di 6 cm and D2 -8 cm, respectively. The pipe is covered with a 4-cm thick glass wool insulation [k-0.05 W/ m°C]. Heat is lost to the surroundings at Too,2 - 21°C by natural convection and radiation, with a combined heat transfer coefficient of h- 18 W/m2 °C. Taking the heat transfer coefficient inside the pipe to...
Calculate a heat loss co-efficient, U_L (W/m2 K) for a 60 mm cylindrical receiver at 200oC in a parabolic trough collection system. The absorber surface has an emissivity of 0.3. The absorber is covered by a glass tubular cover of 90 mm in outer diameter and 4 mm thick with an emissivity of 0.88 and the cover thermal conductivity of 1.4 W/m K. The space between the absorber and the cover is evaluated. The wind speed is 10 m/s and...
Consider a large plane wall of thickness L= 0.5 m, thermal conductivity k = 2.5 W/m °C, and surface area A = 50 m². The left side of the wall is maintained at constant temperature To = 100 °C, while the right side is maintained at T4 = 10 °C. Taking the nodal spacing to be 4x = 12.5 cm: 1. obtain the finite difference formulation for all internal nodes (1,2,3), 2. determine the internal nodal (1,2,3) temperatures by solving...