[Fins] A straight fin of rectangular cross section fabricated from an aluminum alloy (k =185 W /m · K) has a base thickness of t = 3 mm and a length of L = 15 mm. Its base temperatureis T, = 100°C, and it is exposed to a fluid for which T = 20°C and h = 50 W /m² · K.For the foregoing conditions and a fin unit width, calculate the fin heat rate, efficiency,and effectiveness.b. Compare the foregoing results with those for a fin fabricated from pure copper (k =400 W /m · K). Comment your observation from the contrasting results.

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Answered: [Fins] A straight fin of rectangular…

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.

Chapter8: Natural Convection

Section: Chapter Questions

Problem 8.10P

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A furnace wall is to consist in series of 7 in of kaolin firebrick, 6 in of kaolin insulating brick, and sufficientfireclay brick to reduce the heat loss to 100 Btu/ hr ft2 when the face temperatures are 1500 and 100°F,respectively.a) Show the figure of the systemb) What thickness of fireclay brick should be used?c) If an effective air gap of 1/8 in can be incorporated between the fireclay and insulating brick whenerecting the wall without impairing its structural support, what thickness of insulating brick will berequired?
Example 6: Calculate the critical radius of insulation for asbestos [k = 0.17 W/m · ◦C] surrounding a pipe and exposed to room air at 20◦C with h = 3.0 W/m2 · ◦C. Calculate the heat loss from a 200◦C, .5cm-diameter pipe when covered with the critical radius of insulation and without insulation.
. Estimate the heat-transfer rate per foot of length from a 0.02-in. diameter nichrome wire immersed in water at 240F. The wire temperature is 2200F. 2. Two thousand watts of electrical energy are to be dissipated through copper plates measuring 5 cm by 10 cm by 0.6 cm immersed in water at 390 K. How many plates would you recommend? Substantiate all of the design criteria used.
Industrial pipes One of the ways to keep a pipe warm is by means of a steam tracer, through which an electrical resistance is used around the pipe and in a helical shape throughout its diameter?
To maximize production and minimize pumping costs, crude oil is heated to reduce its viscosity during transportation from a production field. (1) Consider a pipe-in-pipe configuration consisting of concentric steel tubes with an intervening insulating material. The inner tube is used to transport warm crude oil through cold ocean water. The inner steel pipe ( ks = 40 W/m·K) has an inside diameter of Di,1 = 150 mm and wall thickness ti = 20 mm while the outer steel pipe has an inside diameter of Di,1 = 250 mm and wall thickness . Determine the maximum allowable crude oil temperature to ensure the polyurethane foam insulation ( kp = 0.0425 W/m·K) provides an external convection heat transfer coefficient of ho = 500 W/m2·K. The convection coefficient associated with the flowing crude oil is hi = 450 W/m2·K. (2) It is proposed to enhance the performance of the pipe-in-pipe device by replacing a thin ( ta =10 mm) section of polyurethane located at the outside of the inner pipe with an…
Solving Thermal Properties Related Problems Estimate the thermal diffusivity of butter at 20°C.
To maximize production and minimize pumping costs, crude oil is heated to reduce its viscosity during transportation from a production field. (1) Consider a pipe-in-pipe configuration consisting of concentric steel tubes with an intervening insulating material. The inner tube is used to transport warm crude oil through cold ocean water. The inner steel pipe (ks= 40 W/m·K) has an inside diameter of Di, 1= 150 mm and wall thickness ti= 20 mm while the outer steel pipe has an inside diameter of Di, 2= 250 mm and wall thickness to=ti. Determine the maximum allowable crude oil temperature to ensure the polyurethane foam insulation (kp= 0.0675 W/m·K) between the two pipes does not exceed its maximum service temperature of Tp, max= 70°C. The ocean water is at ∞ T∞, o= -5°C and provides an external convection heat transfer coefficient of ho= 500 W/m2·K. The convection coefficient associated with the flowing crude oil is hi= 450 W/m2·K. (2) It is proposed to enhance the performance of the…
To maximize production and minimize pumping costs, crude oil is heated to reduce its viscosity during transportation from a production field. (1) Consider a pipe-in-pipe configuration consisting of concentric steel tubes with an intervening insulating material. The inner tube is used to transport warm crude oil through cold ocean water. The inner steel pipe (ks= 40 W/m·K) has an inside diameter of Di, 1= 150 mm and wall thickness ti= 20 mm while the outer steel pipe has an inside diameter of Di, 2= 250 mm and wall thickness to=ti. Determine the maximum allowable crude oil temperature to ensure the polyurethane foam insulation (kp= 0.0675 W/m·K) between the two pipes does not exceed its maximum service temperature of Tp, max= 70°C. The ocean water is at ∞ T∞, o= -5°C and provides an external convection heat transfer coefficient of ho= 500 W/m2·K. The convection coefficient associated with the flowing crude oil is hi= 450 W/m2·K. (2) It is proposed to enhance the performance of the…
Write the expression for critical radius of insulation for a cylindrical pipe. Consider aninsulated pipe exposed to the atmosphere. Will the critical radius of insulation begreater on calm days or on windy days? Why?
You are designing a PCB laid horizontally on the ground. The PCB surface temperature can’t exceed 85℃ and has a size of 96mm x 90mm. Tinfinity = 45oC. "p" is the perimeter of the plate a) Calculate the Rayleigh number. b) If the PCB is laid hot-side UP, what is the Nusselt number and heat transfer coefficient? c) If the PCB is laid hot-side DOWN, what is the Nusselt number and heat transfer coefficient? d) Given your results from b and c, which one has better heat transfer? In that case, what is the maximum power dissipation the board can put out? Properties of Air:k = 0.025 W/mkPr = 0.72v = 1.847 x 10−5u = 16.84 x10−6p = 1.2 kg/m3B =1/ Tf (idwal gass)
Consider two aluminum (k=180 W/mK) pin-fin heat sinks with 1 mm and 2 mm square pins both 25 mm long. Assume that the gap between the pins = side of the pin, ie the one mm pin-fin heat sink has 1 mm gap between its pins. Assuming the module base is 50 mm x 50 mm and the heat sink cannot overhang due to lack of space, and h = 40 W/m?K with jet impingement, calculate: (a) Cooling surface area ratio (1 mm heat sink/ 2 mm heat sink) (b) Heat transfer ratio (1 mm heat sink/2 mm heat sink) Try to fit the maximum number of pins on the 50 mm x 50 mm base.
6. Air flows at 120 o C in a thin-walled tube (k = 18 W/m o C) with h = 65 w/m 2 - o C. The inside diameter of the tube is 2.5 cm tand the thickness is 0.4 mm. The tube is exposed to an environment with h = 6.5 W/m 2 - o C and temperature of 15 o C. Calculate the the heat loss for 1 m length. What thickness of insulation having k = 40 W/m- 0 C should be added to reduce heat loss by 90 %.

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