Consider two long, slender rods of the same diameter but different materials. One end of each rodis attached to a base surface maintained at 100 °C, while the surfaces of the rods are exposed toambient air at 20 °C. By traversing the length of each rod with a thermocouple, it was observedthat the temperatures of the rods were equal at the positions xд =0.15 m and x = 0.075 m, wherex is measured from the base surface. If the thermal conductivity of rod A is known to be k₁ = 70W/m*K, determine the value of kg for rod B.ASSUMPTIONS: (1) Steady-state, (2) One-dimensional conduction along rods, (3) Constantproperties, (4) Negligible radiation, (5) Negligible contact resistance at base, (6) Infinitely longrods, (7) Rods are identical except for their thermal conductivity.

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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 8.8P

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The air-conditioning system in a Chevrolet van for use in desert climates is to be sized. The system is to maintain an interior temperature of 20C when the van travels at 100 km/h through dry air at 30C at night. If the top of the van is idealized as a flat plate 6 m long and 2 m wide and the sides as flat plates 3 m tall and 6 m long, estimate the rate at which heat must be removed from the interior to maintain the specified
A horizontal, 3-mm-thick flat-copper plate, 1-m long and 0.5-m wide, is exposed in air at 27C to radiation from the sun. If the total rate of solar radiation absorbed is 300 W and the combined radiation and convection heat transfer coefficients on the upper and lower surfaces are 20 and 15W/m2K, respectively, determine the equilibrium temperature of the plate.
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Indirect Cooling With Liquid Nitrogen. You are designing a system to cool an insulated silver plate of dimensions 2.00 cm × 2.00 cm × 0.60 cm. One end of a thermally insulated copper wire (diameter D = 2.70 mm and length L = 18.0 cm) is dipped into a vat of liquid nitrogen (T = 77.2 K), and the other end is attached to the bottom of the silver plate.(a) If the silver plate starts at room temperature (65.0 °F), what is the initial rate of heat flow between the plate and the liquid nitrogen reservoir?(b) Assuming the rate of heat flow calculated in part (a), estimate the temperature of the silver plate after 30.0 seconds.
A double window called thermopane is one in which two layers of glass are used separated by a layer o dry stagnant air: In a given window, each of the glass layers is 6.35 mm thick separated by a 6.35 mm space of stagnant air. The thermal conductivity of the glass is 0.869 W/m K and that of air is 0.026 over the temperature range used. For temperature drop of 27.8 K over the system, calculate the heat loss for a window 0.914 m 1.83 m.
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In many manufacturing plants, individuals are often working around high temperature surfaces. Exposed hot surfaces that are potential for thermal burns on human skin tissue are considered to be hazards in the workplace. Metallic surface of temperature above 70°C is considered extremely high temperature in the context of thermal burn, where skin tissue damage can occur instantaneously upon contact with the hot surface.. Consider an AISI 1010 carbon steel strip (p = 7832 kg/m3) of 2 mm thick and 3 cm wide that is conveyed into a chamber to be cooled at a constant speed of 1 m/s. The steel strip enters the cooling chamber at 597 C. Determine the amount of heat rate that needed to be removed so that the steel strip exits the chamber at 47°C to avoid instantaneous themal burn upon accidental contact with skin tissue. Discuss how the conveyance speed can affect the neat rate needed to be removed from the steel strip in the cooling chamber. FIGURE P1-25 Cooling chamber Steel strip Im/s =47°C…

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