Problem set 2: 4CheB grp 3 Gat Granada Angel Salcedo Jamie hendrix Kay Villaflor Jan Rannel Alejandro

1. Problem Set on Conduction Gat Granada Jamie hendrix Angel Salcedo Kay Villaflor Jan Rannel Alejandro Group 3 4ChEB

4. 0.23m 315°C 38°C

5. Solution: k = 0.006T + 1.4 x 10^-6 km = 0.006(T2 +T1)/2 – 1.4 x 10^-6 (T2^2 + T2T1 + T1^2) T2 = 588.15K T1 = 311.15 K Am = 1m^2 km = 2.4059 Wm/K q/(Am) = kmdT/dx = 2.4059 x (588.15-311.15) /(.23-0) q/(Am) = 2897.54 w/m^2

8. Do = 0.0735 Di = 0.0245 Do = 0.1225 Di = 0.0735 Assume k1 = 1W/mK k2 = 4W/mK q = ∆T/∆R R1 = ∆x / KmAm = 0.0245/(1)(0.1401L) = 0.1748/L Am = ∏L (Do – Di) [ln(Do/Di)] R2 = ∆x / KmAm = 0.0245/(4)(0.3014L) = 0.0203/L q = ∆T / [(0.1748/L) + (0.0203/L)] q = ∆T / [(0.1951/L)]

9. Geankoplis: 4.3-2, 5.3-3

10. 5.3-3 Cooling of a Slab of Aluminum. A large piece of aluminum that can be considered a semi-infinite solid initially has a uniform temperature of 505.4K. The surface is suddenly exposed to an environment at 338.8K with a surface convection coefficient of 455W/m 2 -K. Calculate the time in hours (hr) for the temperature to reach 388.8K at a depth of 25.4mm. The average physical properties are α =0.340m 2 /hr and k=208W/m-K.

17. THANK YOU