A long cylindrical rod has a 20-cm-diameter at a uniform temperature of 600°C. The rod is then allowed to cool slowly in a room at 200°C with a heat transfer coefficient of 80 W/m² °C. Calculate the temperature at the center of the rod 45 min after the start of the cooling process. Also, determine the heat transfer unit length of the rod during this time period. per

A long cylindrical rod has a 20-cm-diameter at a uniform temperature of 600°C. The rod is then allowed to cool slowly in a room at 200°C with a heat transfer coefficient of 80 W/m² °C. Calculate the temperature at the center of the rod 45 min after the start of the cooling process. Also, determine the heat transfer unit length of the rod during this time period. per

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter9: Heat Transfer With Phase Change

Section: Chapter Questions

Problem 9.15P

See similar textbooks

Similar questions

Determine the rate of heat transfer per meter length from a 5-cm-OD pipe at 150C placed eccentrically within a larger cylinder of 85 magnesia wool as shown in the sketch. The outside diameter of the larger cylinder is 15 cm and the surface temperature is 50C.
A slab of aluminium 10 cm thick is originally at a temperature of 500°C. It is suddenly immersed in a liquid at 100°C resulting it a heåt transfer coefficient of 1200. W/m2K. Determine the temperature at the center line and the surface 1 min after the immersion. Also the total thermal energy removal per unit area of slab during this period. The properties of aluminium for the given condition are, a = 8.4 x 10-5 m?/s, k =215 W/mK, p = 2700 kg/m3, C= 0.9.kJ/kgK.
Water hardening process of 2 m long and 0.05 m diameter steel bars will be carried out. The steel bar, which is heated up to 900 °C in the oven, is cooled to an average temperature of 100 °C in a water bath. The water bath is kept at a uniform temperature of 30 °C and the heat transfer coefficient between the water and the rod surface is 325 W/m2K. Accordingly, calculate the time required for the steel bar to cool to 100°C in the water bath. (Steel bar p=7832 kg/m3, cp=434 J/kgK, k=63.9 W/mK)
A thick concrete wall fairly large in size initially at 30 oC has its surface temperatureincreased to 600 oC by an intense fire which lasted for 25 minutes. The material maydisintegrate up to a depth where the temperature reaches 400 oC. Determine thethickness which may disintegrate and the heat flow at this depth and the total heatflow during that time. The thermal diffusivity is 4.92 x 19-7 m2/s and k = 1.28 W/m-K.
A thick brick wall (fired clay) initially at 20°C is exposed to flames at 800°C. Plot the temperature as a function of timefor the first 10 minutes both at the surface and 2 cm into the wall. Assume a film coefficient of 90 W/m2K.
A 6 cm diameter sphere is initially at a temperature of 100C. Later, this sphere was thrown into water at 800C. Calculate how long it will take for the center temperature of the sphere to reach 500C by taking the convection heat transfer coefficient as 80W / m2K.
asap
-3-A piece of copper as shown in figure is initially at 150 C when suddenly immersed in an environment at 38 C. Determine the Biot number and find the piece temperature after 1 minute, a) if the environment is water with h= 50 W/m2 K b) if the environment is air with h= 12 W/m2 K Data: k = 374 W/m K, c, 0.381 kJ/kg K, and p= 8938 kg/m3. Answ(a- Bi=0.0008913 ; T=136.1C b- Bi=0.0002139 ; T=146.5C). 4 cm 4 cm
In a quenching process, a copper plate of 3 mm thick is heated up to 350°C and then suddenly, it is dropped into a water bath at 25°C. (a) Calculate the time required for the plate to reach thetemperature of 50°C. The heat transfer coefficient on the surface of the plate is 28 W/m2 -K. The plate dimensions may be taken as length 40 cm and width 30 cm. (b) Also calculate the time required for infinite long plate to cool to 50°C. Other parameters remain same. (c) Calculate the heat transfer rate loss of the plate when it is at 50°C. Take the properties of copper as: CP = 380 J/kg-K, ρ = 8800 kg/m3 , k = 385 W/m-K
Steel balls (diameter 21 mm,p 1.474x10 m s) are annealed by heating them first to 870°C in a furnace and then allowing them to cool slowly to 85°C in ambient air at 27 C. The average heat transfer coefficient is 51 W/m°C. How long the annealing process will take (in Seconds) 7833 kg/m, k 54 Win C, Cp-0465 Cand
Q2/ A 3-m internal diameter spherical tank made of 2-cm-thick stataless steel (k= 15 W/m 0°C. The tank is located in a room whose %3D C) is used to store iced water at Te temperature is T-22°C. The walls of the room are also at 22°C. The outer surface of the tank is black and heat transfer between the outer surface of the tank and the surroundings is by natural convection and radiation. The convection heat transfer coefficients at the inner and the outer surfaces of the tank are h-80 W/m2 C and h 10 W/m2 C, respectively. Determine (a) the rate of heat transfer to the iced water in the tank and (b) the amount of ice at 0°C that melts during a 24-h period.
Shown below is an insulated copper block that receives energy at a rate of 100 W from anembedded resistor. If the block has a volume of 10-3 m3and an initial temperature of 20oC, howlong would it take, in minutes, for the temperature to reach 60oC? Copper has a specific heatcapacity ccu = 0:385 kJ/ kg.K and a density of cu = 8930 kg/m3.