Cairo University Faculty of Engineering Communication and Computer Science Dept. 2nd Semester 2017/2018 Mechanical Engineering INTN125 Internal Heat Generation 1- Heat is generated uniformly in a stainless-steel plate having k = 20 W/m.°C. The thickness of the plate is 1.0 cm and the heat-generation rate is 500 MW/m3. If the two sides of the plate are maintained at 100 and 200°C, respectively, calculate the temperature at the center of the plate. 2- A 3.2-mm-diameter stainless-steel wire 30 cm long has a voltage of 10 V impressed on it. The outer surface temperature of the wire is maintained at 93°C. Calculate the center temperature of the wire. Take the resistivity of the wire as 70 μῼ.cm and the thermal conductivity as 22.5 W/m.°C. 3- A plane wall is a composite of two materials, A and B. The wall of material A has uniform heat generation q’’’=1.5*106 W/m3, kA = 75 W/m.K, and thickness LA = 50 mm. The wall material B has no generation with kB = 150 W/m.K and thickness LB = 20 mm. The inner surface of material A is well insulated, while the outer surface of material B is cooled by a water stream with T∞ = 30°C and h = 1000 W/m2.K. Sketch the temperature distribution that exists in the composite under steady-state conditions and determine the temperature T0 of the insulated surface as well as the temperature T2 of the cooled surface. Cairo University Faculty of Engineering Communication and Computer Science Dept. Heat Transfer Datasheet General Equation of Conduction Cartesian: Cylindrical: Spherical: 2nd Semester 2017/2018 Mechanical Engineering INTN125 Cairo University Faculty of Engineering Communication and Computer Science Dept. Free Convection Parallel flow over a flat plate: Cross flow over a cylinder: Cross flow over a sphere: 2nd Semester 2017/2018 Mechanical Engineering INTN125 Cairo University Faculty of Engineering Communication and Computer Science Dept. 2nd Semester 2017/2018 Mechanical Engineering INTN125 Free Convection Long Horizontal Cylinder: Horizontal Flat Plate: Where the characteristic length (L) equals the area divided by the perimeter of the plate. Vertical Flat Plate: Sphere: Cairo University Faculty of Engineering Communication and Computer Science Dept. 2nd Semester 2017/2018 Mechanical Engineering INTN125 Thermodynamic properties of air at atmospheric pressure: Cairo University Faculty of Engineering Communication and Computer Science Dept. Thermodynamic properties of engine oil: 2nd Semester 2017/2018 Mechanical Engineering INTN125
