Ten circular fins of uniform cross section, D=15mm, and a length of 75mm, are attached to a 1m2 wall with surface temperature of 375o The fins are made of a material with k=240W/mK. It is exposed to ambient air at 20oC with a convective heat transfer coefficient 75W/m2K. Use the approximation to change a convective tip to an adiabatic tip. Use equations from table 3-3 (p. 177) and equation 3-69 through 3-78 to determine: Temperature at the end of the pin. Heat transfer from the fin. Fin efficiency. Individual fin effectiveness. Overall fin effectiveness.

Ten circular fins of uniform cross section, D=15mm, and a length of 75mm, are attached to a 1m2 wall with surface temperature of 375o The fins are made of a material with k=240W/mK. It is exposed to ambient air at 20oC with a convective heat transfer coefficient 75W/m2K. Use the approximation to change a convective tip to an adiabatic tip. Use equations from table 3-3 (p. 177) and equation 3-69 through 3-78 to determine: Temperature at the end of the pin. Heat transfer from the fin. Fin efficiency. Individual fin effectiveness. Overall fin effectiveness.

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.

Chapter3: Transient Heat Conduction

Section: Chapter Questions

Problem 3.10P: 3.10 A spherical shell satellite (3-m-OD, 1.25-cm-thick stainless steel walls) re-enters the...

See similar textbooks

Similar questions

Determine the rate of heat transfer per meter length to a light oil flowing through a 2.5-cm-ID, 60-cm-long copper tube at a velocity of 0.03 m/s. The oil enters the tube at 16C, and the tube is heated by steam condensing on its outer surface at atmospheric pressure with a heat transfer coefficient of 11.3 kW/m K. The properties of the oil at various temperatures are listed in the following table: Temperature, T(C) 15 30 40 65 100 (kg/m3) 912 912 896 880 864 c(kJ/kgK) 1.80 1.84 1.925 2.0 2.135 k(W/mK) 0.133 0.133 0.131 0.129 0.128 (kg/ms) 0.089 0.0414 0.023 0.00786 0.0033 Pr 1204 573 338 122 55
7.43 Liquid sodium is to be heated from 500 K to 600 K by passing it at a flow rate of 5.0 kg/s through a 5-cmID tube whose surface is maintained at 620 K. What length of tube is required?
You are designing a 3m x 3m floor with radiant heating. The floor has 12 parallel pex pipes (k = 40 W/mK) of L = 3m, OD = 25mm and ID = 20mm. Hot water (TInfintiy 1 = 90oC, h = 200 W/m2K) runs through the pipes continuously. The surface below the pipes is perfectly insulated. Above the pipes, there is a 3mm layer of bonding material (? = 12 W/mK) and a 9mm layer of tile (k = 2 W/mK). Above the tile, there is air (TInfinity 2 = 25oC, h = 20 W/m2K). Properties of Air: k = 0.025 W/mK, Pr = 0.72, v = 1.847 x 10−5, u = 16.84 x 10−6, p = 1.2 kg/m3, B = 1/Tf (ideal gas), Hint: Assume that the “layer” of pipe starts at the center point (e.g. for conduction purposes, the pipe is OD divided by 2 thick). For convection, consider the entire pipe surface. a) What is the total heat rate entering the room above the floor? b) What is the temperature of the top of the tile?
A glass door is used on a fireplace to reduce exfiltration of room air through the chimney. The door, 0.70m high and 1.00m wide, reaches a uniform temperature of 232oC. If the room air temperature is 23oC, estimate the rate of heat transfer to the room air due to convection. Air properties: k=0.0338W/m-K ν=26.4x10-6 m2/s Pr=0.690
Ten circular fins of uniform cross section, D=15mm, and a length of 75mm, are attached to a 1m2 wall with surface temperature of 375o The fins are made of a material with k=240W/mK. It is exposed to ambient air at 20oC with a convective heat transfer coefficient 75W/m2K. Use the approximation to change a convective tip to an adiabatic tip. Use equations from table 3-3 (p. 177) and equation 3-69 through 3-78 to determine: Individual fin effectiveness. Overall fin effectiveness.
ать Tb=250°C 8mm 120mm -L=S = 50mm K-300 W mk h=160W/m²K Too = 32°C Tmm nfin= ? Determine the temperature distrubition of the fin shown in figuere. Tip of the fin is adiabatic Continuous Accept it as an one-dimensional heat transfer. in a regime for the thin-tip air foil with the Shape shown in figure.
i. A very long rod 5 mm in diameter has one end maintained at 100 oC. The surface of the rod is exposed to ambient air at 25 oC with convection heat transfer coefficient of 100 W/m2-K and thermal conductivity is 180 W/m-K. Determine the temperature distribution along the rod and What is the heat loss. ii. Water flows on the inside of a steel pipe with an ID of 2.5 cm. The wall thickness is 2 mm, and the convection coefficient on the inside is 500 W/m2◦C. The convection coefficient on the outside is 12 W/m2 ◦C. Calculate the overall heat-transfer coefficient.
A spherical shaped vessel of 1.4 m diameter is 90 mm thick. Find the rate of heat leakage, if the temperature difference between the inner and outer surfaces is 220oC. Thermal conductivity of the material of the sphere is 0.083 W/m-K.
4.) A 15-cm-diameter steam line carries saturated steam at 6 MPa and is located in a tunnel with stagnant air with a temperature of 50oC. The outside unit convective coefficient is 8.5 W/m2-K. The steam line is covered with 3 cm of 85% magnesia insulation. It is decided to reduce the heat loss by one-half. How much 85% magnesia insulation is required? Neglect thermal resistance of pipe and inside surface.
Solve for this : An engine cover is made from 1 cm thick stainless steel plate (k = 14 W/m K). Air on the inside of the engine cover is heated to 340°C with a heat transfer coefficient of 7 W/m2K. Outside of the engine coverthe ambient air has a temperature of 70°C. If oil was spilled on the outside of the engine cover (ambient side), it could ignite if the surface temperature were to exceed 200°C. In this configuration, would spilled oil ignite? Use calculations to justify your answer. If a 4 mm thermal coating (k = 1.1 W/m K) was applied tothe outside of the engine, what would the outside temperature of the engine cover be reduced to?
a) A turbine blade 6 cm long and having a cross sectional area 4.65 cm and perimeter 12 cm is made of stainless steel (k=23.3 Wim K). The temperature at the root is 500 C. The blade is exposed to a hot gas at 870 °C. The heat transfer coefficient between the blade surface and gas is 442 W/im K. Determine the temperature distribution and rate of beat flow at the root of the blade, Assume the tip of the blade to be insulated. b) The hot combustion gases of a fumace are separated from the ambient air and its surounding, which are at 20°C, by a brick wall 0.5 m thick. The brick has a themal conductivity of 5 W/mk and a surface emissivity of 0.6. Under steady-state conditions an Page no.1 of 1 outer surface temperature of 120°C is measured Free convection heat transter to the air adjoining the surface is characterized by a convection coefficient of 15 Wim K What is the brick inner surface temperature
Hot wastewater of a heat recovery system is flowing through a concrete conduct (k = 1.4 W/m-K) of square cross section. The flow section of the duct is 40 cm x 40 %3D cm, and the thickness of the wall is 10 cm as shown in figure (next page). The average temperature of the hot water in the conduct is T, = 300°C. The conduct is %3D losing heat from its outer surface to the ambient air at T 12°C by convection with a heat transfer coefficient of h = 35 W/m2 K. Using the finite difference %3D method with Ar Ay 5 cm and taking full advantage of symmetry: a) obtain the finite difference formulation of this problem for steady two- dimensional heat transfer. b) determine the temperatures at the nodal points of a cross section. c) evaluate the rate of heat loss for a 1-m-long section of the conduct.