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Unformatted text preview: ME 324 HW #2 07.03.2011 1. Steam at 320C flows in a case iron pipe (k = 80 W/m C) whose inner and outer diameters are 5 cm and 5.5 cm, respectively. 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 5C by natural convection and radiation, with a combined heat transfer coefficient of h = 18 W/m2 K. Taking the heat transfer coefficient inside the pipe to be h = 60 W/m2 K, determine (1) the rate of heat loss from the steam per unit length of the pipe, and (2) the temperature drop across the insulation. insulation T,o r2 r1 T,i r3 2. A wire of 1.0 mm in diameter is maintained at a temperature of 200C and exposed to a convection environment at 30C with the convective heat transfer coefficient of 60 W/m2 C. (1) What will be the heat loss per unit length (1 m) if there is no insulation on the wire? (2) Now it is planned to use the glass fiber as an insulator for the wire. The glass fiber has the thermal conductivity of 0.04 W/m C. What will be the critical radius of insulation? (3) If the glass fiber of 1 mm in thickness is applied to the wire, what will be the heat loss per unit length? 3. Heat is generated in a 2.5 cm by 2.5 cm copper rod at the rate of 35.3 MW/m3. The rod is exposed to a convection environment at 20C, and the heat transfer coefficient is 4000 W/m 2 C. Calculate the surface temperature of the rod. 4. A triangle fin of stainless steel (18% Cr, 8% Ni), whose thermal conductivity is 16.3 W/m K, is attached to a plane wall maintained at 460C. The fin thickness is 6.4 mm and the length is 2.5 cm. The environment is at 93C, and the convection heat transfer coefficient is 29 W/m2 K. Calculate (1) the fin efficiency, (2) the fin effectiveness, and (3) the heat loss from the fin per unit width. ...
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This note was uploaded on 10/05/2011 for the course ME me352 taught by Professor Koraykadirsafak during the Spring '11 term at Yeditepe Üniversitesi.
- Spring '11