4-79 White potatoes (k0.50 W/m-K and 0.13 X 10-6 m/s) that are initially at a uniform temperature of 25°C and have an a...
QUESTION 4 The temperature distribution for a long fin with uniform cross section is cosh[m(L - x)] cosh(ml) where b means base, O = T - To, m= rand A and P are the area and perimeter of the cross- section. K is in air at A long copper rod of diameter D = 1.5 cm, L = 20 cm, and thermal conductivity 380 W/ m 20°C. The temperature at the base is 150°C. If m = 6 m-7, the...
A household oven door of 0.6-m height and 0.7-m width reaches an average surface temperature of 32°C during operation. The temperature of ambient air is 22°C. Assuming the door has an emissivity of 0.8 and the surroundings are also at 22°C, determine the heat transfer by free convection and the heat transfer by radiation. 1) What is the volumetric thermal expansion coefficient of air at the film temperature outside the oven door, in 1/K? 2) What is the Rayleigh number...
An ordinary potato (k = 0.6 W/m.K and α = 0.13 × 10 -6 m2 /s) can be approximated as a 6-cm diameter sphere. The potato is initially at a uniform temperature of 200 C and is to be baked in an oven with air temperature of 1800 C. The average convection coefficient between the potato and the air is experimentally determined to be 15 W/m2 .K. Determine how long it will take for the surface temperature of the potato...
Consider a long solid bar (K=45 W/m*k and ∝=12x10-6 m2/s) of square cross section that is infinity at uniform temperature of 450°C. The cross section of the bar is 20cmx20cm in size. All four sides of the bar are subjected to convection of ambient air at T=20°C with a heat transfer coefficient of (h=40 W/m2*K) Using the explicit finite difference method with a mesh (Δx=Δy = 10 cm), determine the centerline temperature “C” of the bar after 5 minutes. Question...
Question Water at an average temperature of 110°C and an average velocity of 3.5 m/s flows through a 5-m-long Beryllium Copper (k-66 w/m.k) tube merge in a boiling water tank. Do NOT ignore the wall resistance. The inner and outer diameters of the tube are Di 1.0 cm and Do 2 cm, respectively. If the convection heat transfer coefficient at the outer surface of the tube where boiling is taking place is ho- 8400 W/m2.K, a) Determine the overall heat...
Problem 3 (30): Steam at Too,1 340 °C flows in a cast iron pipe [k- 80 W/m.°C] whose inner and outer diameter are Di 6 cm and D2 -8 cm, respectively. The pipe is covered with a 4-cm thick glass wool insulation [k-0.05 W/ m°C]. Heat is lost to the surroundings at Too,2 - 21°C by natural convection and radiation, with a combined heat transfer coefficient of h- 18 W/m2 °C. Taking the heat transfer coefficient inside the pipe to...
[6] A 20-cm thick wall of a house made of brick (k = 0.72W/m. C) is subjected to inside air at 22.C with a convection heat-transfer coefficient of 15 W/m2. C. The inner surface temperature of the wall is 18 C and the outside air temperature is -1 °C. Determine the outer surface temperature of the wall and the heat-transfer coefficient at the outer surface.
Consider a long solid bar (k=30W/m K and α 12X10-6 m /s) ofAare cro s section that is initially at uniform room temperature of 150° C. The cross seftion of the bar is 20 cm X 20 cm in size. All four side of the bar are subjected to donJeation td the ambient air at T-25oC with a heat transfer coefficient of h t45 W/m2K. Using the explicit finite difference method with a mesh Δ x = Δ y-10cm</determine the...
Consider a 4 m high, 6 m wide and 0.17 m thick wall whose thermal conductivity is k = 0.8 W/m.oC. On a certain day, the temperatures of the inner and the outer medium close to the wall are measured to be 14oC and 6oC, respectively. Both inner and outer surfaces are subjected to convection heat transfer. Assume that the convection heat transfer coefficient is the same for the two surfaces h = 5 W/m2 ∙ °C. 1. Draw the...
heat and mass transfer (20 points) Air at 25°C cools a 2170 cylindrical battery (with a diameter of 21 mm and a length of 70 mm) with a cross flow velocity of 6 m/s. a) Determine the average convective heat transfer coefficient. (b) If the battery's internal heat generation is 5W and its thermal conductivity is 0.6 w/m-k, the determine the battery surface temperature and the maximum temperature in battery (20 points) Air at 25°C cools a 2170 cylindrical battery...