Example 2 A cylindrical steam pipe having an inside surface temperature of 250 °C has an inside diameter of 8 cm and a wall thickness of 5,5 mm. It covered with a 9 cm layer of insulation having k= 0.5 W / m °C, followed by a 4 cm layer of insulation having k = 0.25 W/ m °C. Outside temperature of the insulation is 20°C Calculate the heat lost per meter of length. Assume K = 47 W/m°C. for the pipe

Example 2 A cylindrical steam pipe having an inside surface temperature of 250 °C has an inside diameter of 8 cm and a wall thickness of 5,5 mm. It covered with a 9 cm layer of insulation having k= 0.5 W / m °C, followed by a 4 cm layer of insulation having k = 0.25 W/ m °C. Outside temperature of the insulation is 20°C Calculate the heat lost per meter of length. Assume K = 47 W/m°C. for the pipe

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.

Chapter1: Basic Modes Of Heat Transfer

Section: Chapter Questions

Problem 1.4P: 1.4 To measure thermal conductivity, two similar 1-cm-thick specimens are placed in the apparatus...

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3.10 A spherical shell satellite (3-m-OD, 1.25-cm-thick stainless steel walls) re-enters the atmosphere from outer space. If its original temperature is 38°C, the effective average temperature of the atmosphere is 1093°C, and the effective heat transfer coefficient is , estimate the temperature of the shell after reentry, assuming the time of reentry is 10 min and the interior of the shell is evacuated.
1.1 On a cold winter day, the outer surface of a 0.2-m-thick concrete wall of a warehouse is exposed to temperature of –5°C, while the inner surface is kept at 20°C. The thermal conductivity of the concrete is 1.2 W/m K. Determine the heat loss through the wall, which is 10-m long and 3-m high. Problem 1.1
A square silicon chip 7mm7mm in size and 0.5-mm thick is mounted on a plastic substrate as shown in the sketch below. The top surface of the chip is cooled by a synthetic liquid flowing over it. Electronic circuits on the bottom of the chip generate heat at a rate of 5 W that must be transferred through the chip. Estimate the steady-state temperature difference between the front and back surfaces of the chip. The thermal conductivity of silicon is 150 W/m K. Problem 1.6
2.38 The addition of aluminum fins has been suggested to increase the rate of heat dissipation from one side of an electronic device 1 m wide and 1 m tall. The fins are to be rectangular in cross section, 2.5 cm long and 0.25 cm thick, as shown in the figure. There are to be 100 fins per meter. The convection heat transfer coefficient, both for the wall and the fins, is estimated to be K. With this information determine the percent increase in the rate of heat transfer of the finned wall compared to the bare wall.
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A cast iron pipe is used to transfer steam with an inlet temperature of 300 C. Inner radius of the pipe is 15 cm. The thickness of the pipe (k=25 W/(mK)) is 0.7 cm and there is an insulation (k=0.05 W/mK) over the pipe with a thickness of 5 cm. Environmental temperature is -8 C. Determine the steady heat loss from the pipe if the steam convection coefficient is 80 W/(m^2K) and environment convection coefficient is 25 W/(m^2K)? Is insulation thickness enough? a)197 W, yesb)207 W, yesc)147 W, yesd)150 W, noe)none
A cast iron pipe is used to transfer steam with an inlet temperature of 350 C. Inner radius of the pipe is 5 cm. The thickness of the pipe (k=20 W/(mK)) is 0.5 cm and there is an insulation (k=0.07 W/mK) over the pipe with a thickness of 4 cm. Environmental temperature is -5 C. Determine the steady heat loss from the pipe if the steam convection coefficient is 70 W/(m^2K) and environment convection coefficient is 20 W/(m^2K)? Is insulation thickness enough? a)167 W, yes b)187 W, yes c)147 W, yes d)120 W, no e)none
A cast iron pipe is used to transfer steam with an inlet temperature of 300 C. Inner radius of the pipe is 15 cm. The thickness of the pipe (k=25 W/(mK)) is 0.7 cm and there is an insulation (k=0.05 W/mK) over the pipe with a thickness of 5 cm. Environmental temperature is -8 C. Determine the steady heat loss from the pipe if the steam convection coefficient is 80 W/(m^2K) and environment convection coefficient is 25 W/(m^2K)? Is insulation thickness enough?
A hot steam pipe having an inside surface temperature of 250°C has an inside diameter of 8 cm and a wall thickness of 5.5 mm. It is covered with a 9-cm layer of insulation having k =0.5 W/m-°C, followed by a 4-cm layer of insulation having k =0.25W/m-°C. The outside temperature of the insulation is 20°C. Calculate the heat lost per meter of length. Assume k =47 W/m-°C for the pipe.
A 50-cm-diameter pipeline in the Arctic carries hot oil at 30°C and is exposed to a surrounding temperature of −12°C. A special powder insulation 5 cm thick surrounds the pipe and has a thermal conductivity of 7 mW/m°C. The convection heat transfer coefficient on the outside of the pipe is 9 W/m2°C. Estimate the energy loss from the pipe per meter of length.
Consider a closed cylindrical reactor vessel of diameter D= 1 ft, and length L= 1.5 ft. The surface temperature of the vessel, T1, and the surrounding temperature, T2, are 390 deg. F and 50 deg. F, respectively. The convective heat transfer coefficient, h, between the vessel wall and surrounding fluid is 4.0 Btu/h . ft . ⁰F. Calculate the thermal resistance in ⁰F .h/Btu.
A 50-cm-diameter pipeline in the Arctic carries hot oil at 30°C and is exposed to a surrounding temperature of - 20 degrees * C A special powder insulation 5 cm thick surrounds the pipe and has a thermal conductivity of 7 mW/m °C. The convection heat-transfer coefficient on the outside of the pipe is 9 W / (m ^ 2) °C. Estimate the energy loss from the pipe per meter of length.