Group 1 4ChE B Almazar, Karina Ascalon, Kristine Malana, Rebecca Rozario, Vera Cresta Tancio, Romar
1.) A steam pipe 5 cm outside diameter has an outside surface temperature of 175 °C. The pipe is covered with a coating material 5 cm, thick. The thermal conductivity of the coating varies with the temperature such that, k= 0.89 + 0.0015T where T is in °C and k in W/mK. The outside surface of the coating is at 38 °C. Calculate the heat loss per meter of pipe length.
Given: D= 5cm L= 1m T1= 175°C T2= 38°C
k2= 0.89 + 0.0015T
K2 = 0.89 + 0.0015(38°C) = 0.947 W/mK
Do = 0.05 + 0.05(2) = 0.15 m
Di = 0.05 m
9.) A small electric furnace is 15 by 15 by 30 cm inside dimensions and has fire-brick walls (k= 1.12 W/mK) 2m thick. The front of the furnace is movable wall which permits entry into the furnace. In this section is by a 5 by 5 by 0.6 cm quartz observation windows (k= 0.07 W/mK). The inner temperature for all sides is 1100 °C, and the outer surface temperature is 121°C. Assuming all joints perfectly made and neglecting the influence of the corners on the temperature distribution, what is the heat loss from this furnace?.
Solution 1 2 4 5 3 0.15 m 2m 0.30m GIVEN: q T=1100 0 C T=121 0 C 3 is .05 x .05 x .006
k= 1.12 W/mK
5.2-1. Temperature Response in Cooling a Wire. A small copper wire with a diameter of 0.792 mm and initially at 366.6 K is suddenly immersed in a liquid held constant at 311 K. The convection coefficient h=85.2W/m2. K. The physical properties can be assumed constant and are k=372 W/m.K , Cp=0.389 kJ/kg.K ρ = 8890kg/m 3
a. Determine the time in seconds for the average temperature of the wire to drop to 338.8K (one-half the initial temperature difference).
b. Do the samew but =11.36W/m2.K.
c. For part (b), calculate the total amount of heat removed for a wire 1.0 m long.
4.3-4. Heat Loss from Steam Pipeline. A steel pipeline, 2-in. schedule 40 pipe, contains saturated steam at 121.1 0 C. The line is covered with 25.4 mm of insulation. Assuming that the inside surface temperature of the metal wall is at 121.1 0 C and the outer surface of insulation is at 26.7 0 C , calculate the heat loss for 30.5 m of pipe. Also, calculate the kg of steam condensed per hour in the pipe due to the heat loss. The average k for steel from Appendix A.3 is 45 W/m. K and the k for the insulation is 0.182.
Given: 2” Sch 40 steel pipe L = 30.5m K s = 45W/m.K