(1 point) A large cylinder with diameter D = 55 cm is at uniform temperature of T, = 450° C. A fan that blows air at temperature T㎡ = 25°C to cool the cylinder down. The convection coefficient is estimated to be h 110W/m2. K. The safe temperature for handling is Tsafe 55'C. The properties of the cylinder are p 2700 kg/m3,c975 J/kg.K and k 20 W/m.K. A conservative measure imposes that the entire object has to reach to the...
Problem 2. A long 6.5 cm diameter solid cylinder steel (K 16.3 W/m. K,p 7817 kg/m3, Cp 460 J/kg.k). It's initially at a uniform temperature of T 150°C. It is suddenly exposed to a convection environment with h-285 W/m2 K and Too 50°C. Calculate the temperature at 1.) the axis of the cylinder, and 2.) a 2.5 cm radial distance after 5 min of exposure to the cooling flow. (20%)
Problem 3 (50 points). A long stainless steel cylinder with diameter of d=55cm is heated up to 450°C. The cylinder is then cooled slowly in a chamber at 150°C with an average convection heat transfer coefficient of h = 70 W/m2.°C. (a) Find the temperature at the center of the cylinder after 25 min. (b) Find the heat transfer per unit length of the cylinder during this time period. Cylinder properties: k=15 W/m•°C, p=8000 kg/m², c=477 J/kg•°C, a=3.95x10-6 m²/s.
Q3. A very long horizontal cylinder of Unobtainium, of diameter 100 mm, is initially at a uniform temperature of 500 K. The cylinder is cooled by a fan. The fan blow airs, with a temperature of 300 K, over the cylinder at a velocity of 6 m/s in a direction perpendicular to the axis of the cylinder. Calculate a) the average convective heat transfer coefficient at the beginning of the cooling process when the initial temperature of the cylinder is...
4. (25 pts) Water is flowing inside a thin wall, smooth pipe of diameter 0.05 m at a mass flowrate of 0.3 kg/s. The water enters the pipe at a mean temperature Tm,i= 80 °C and exits at Tm,o= 80 °C while the pipe surface temperature is maintained at Ts= 20 °C along its entire length. a. Is the flow turbulent or laminar? b. Calculate the average convection heat transfer coefficient inside the tube. c. Calculate the length of the...
2. A nuclear fuel rod with diameter of D=40 mm and length L=1m, has properties of k=1 W/mK, c=1600J/kg.K, and p=400 kg/m3. (a)Heat is generated uniformly in the rod with q'"' = 2 x 106 W/m?. The rod is first cooled in oil with constant temperature To= 400 K and average heat transfer coefficient h=50 W/m².K. Under steady state, determine the surface temperature of the rod Ts. (10 pts) (b)Now the heat generation in the rod is stopped, where q'"...
2. A nuclear fuel rod with diameter of D=40 mm and length L=1m, has properties of k=1 W/mK, c=1600J/kg.K, and p=400 kg/m3. (a)Heat is generated uniformly in the rod with q'"' = 2 x 106 W/m?. The rod is first cooled in oil with constant temperature To= 400 K and average heat transfer coefficient h=50 W/m².K. Under steady state, determine the surface temperature of the rod Ts. (10 pts) (b)Now the heat generation in the rod is stopped, where q'"...
2. A nuclear fuel rod with diameter of D=40 mm and length L=1m, has properties of k=1 W/mK, c=1600J/kg.K, and p=400 kg/m3. (a)Heat is generated uniformly in the rod with q'"' = 2 x 106 W/m3. The rod is first cooled in oil with constant temperature To= 400 K and average heat transfer coefficient h=50 W/m2K. Under steady state, determine the surface temperature of the rod Ts. (10 pts) (b)Now the heat generation in the rod is stopped, where q'''...
A long cylinder of diameter D 0.012 m, thermal conductivity k 358 W/(mK), density p - 7614 kg/m3, specific heat c 418 J/(kgK) is initially at a uniform temperature of Ti-74°C. The cylinder is suddenly exposed to a gas at T,-18 ℃ The convection coefficient is h -17 W/(m2K). Verify that a lumped capacitance analysis can be used for the transient response of the cylinder temperature. What is the time t in seconds for the cylinder temperature to become Tf-32...
2. A nuclear fuel rod with diameter of D=40 mm and length L=1m, has properties of k=1 W/mK, c=1600J/kg-K, and p=400 kg/m² (a)Heat is generated uniformly in the rod with q'"' = 2 x 106 W/m. The rod is first cooled in oil with constant temperature To= 400 K and average heat transfer coefficient h=50 W/m2K. Under steady state, determine the surface temperature of the rod Ts. (10 pts) (b)Now the heat generation in the rod is stopped, where q"'...