An insulated steam pipe located where the ambient temperature is 32°C, has an inside diameter of 50mm with 10mm thick wall. The outside diameter of corrugated asbestos insulation is 125mm and the surface coefficient of still air, ho = 12 W/m2-K. Inside the pipe is steam having a temperature of 150°C with film coefficient of 6000 W/m2-K. Thermal conductivity of pipe and asbestos insulation are 45 and 0.12 W/m-K respectively. Determine the heat loss per unit length of pipe.

An insulated steam pipe located where the ambient temperature is 32°C, has an inside diameter of 50mm with 10mm thick wall. The outside diameter of corrugated asbestos insulation is 125mm and the surface coefficient of still air, ho = 12 W/m2-K. Inside the pipe is steam having a temperature of 150°C with film coefficient of 6000 W/m2-K. Thermal conductivity of pipe and asbestos insulation are 45 and 0.12 W/m-K respectively. Determine the heat loss per unit length of 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 1.1P: 1.1 On a cold winter day, the outer surface of a 0.2-m-thick concrete wall of a warehouse is exposed...

See similar textbooks

Similar questions

1.4 To measure thermal conductivity, two similar 1-cm-thick specimens are placed in the apparatus shown in the accompanying sketch. Electric current is supplied to the guard heater, and a wattmeter shows that the power dissipation is 10 W. Thermocouples attached to the warmer and to the cooler surfaces show temperatures of 322 and 300 K, respectively. Calculate the thermal conductivity of the material at the mean temperature in W/m K. Problem 1.4
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.
One end of a 0.3-m-long steel rod is connected to a wall at 204C. The other end is connected to a wall that is maintained at 93C. Air is blown across the rod so that a heat transfer coefficient of 17W/m2 K is maintained over the entire surface. If the diameter of the rod is 5 cm and the temperature of the air is 38C, what is the net rate of heat loss to the air?
2.9 In a large chemical factory, hot gases at 2273 K are cooled by a liquid at 373 K with gas-side and liquid-side convection heat transfer coefficients of 50 and , respectively. The wall that separates the gas and liquid streams is composed of a 2-cm thick oxide layer on the gas side and a 4-cm thick slab of stainless steel on the liquid side. There is a contact resistance between the oxide layer and the steel of . Determine the rate of heat loss from hot gases through the composite wall to the liquid.
J 5 A cylindrical steel tank with a diameter of 1.8m and a height of 2m, is insulated with polyurethane on its lateral faces and its lid. The insulation is 40 mm thick and covered with a thin layer of metal. The tank contains water that is kept warm by an electric heater in such a way as to maintain the inner surface of the tank at a temperature of 55C. The ambient air temperature is 10C and the external skin coefficient is 10 w/m2K. If the energy cost is $0.15/kwh. What is the monthly energy cost for water storage?
A steam pipe 75 mm inside and 90 mm outside diameter is lagged with two successive layers of insulation. The layer in contact with the pipe is 38 mm asbestos and the asbestos layer is covered with 25 mm thick magnesia insulation. The convective film coefficients for the inside and outside surfaces are 227 W/m2-K and 6.8 W/m2-K, respectively. The steam temperature is 375oC and the ambient temperature is 35oC. Thermal conductivities in W/m-oC area as follows: pipe material=45, asbestos= 0.14, and magnesia insulation=0.07. Illustrate and label the schematic layout and the equivalent thermal network and calculate (a) the steady state loss of heat transfer for 60 m length of pipe length, (b) the overall heat transfer coefficient based on the outside and inside surface areas of the lagged steam pipe, and (c) the interface temperature between the two layers of insulations.
Question 1: A glass window of width W = 1 m and height H = 2 m is 5 mm thick and has a thermal conductivity of kg =1.4 W/m.K. If the inner and outer surface temperatures of the glass are 15 oC and -20 oC, respectively, on a cold winter day, what is the rate of heat loss through the glass? To reduce heat loss through windows, it is customary to use a double pane construction in which adjoining panes are separated by an air space. If the spacing is 10 mm and the glass surfaces in contact with the air have temperatures of 20 oC and -15 oC, what is the rate of heat loss from a 1 m x 2 m window? The thermal conductivity of air is ka = 0.024 W/m.K.
The door of a 1 m long by 27.5 cm wide oven is made up of 2 AISI 1010 carbon steel plates of identical thickness and an 8 mm thick mineral fiber board with resin binder (intermediate plate) . the composite plate considering the three plates is 5 cm. The temperature on the inner wall of the oven is 172 ° C and the surface temperature on the oven door (outer wall) is 35 ° C. The oven door is exposed in a room where the ambient air temperature is 30 ° C. Do the following: Estimate the convective heat transfer coefficient associated with ambient air.
Steam at 120°C flows in a cast iron pipe (k = 80 W/m K) whose inner and outer diameters are Di = 5 cm and Do = 5.5 cm respectively. The pipe is covered with 3-cm-thick glass wool insulation with k = 0.05 W/m K. Assuming that the inside surface temperature of the pipe wall is at 120°C and the outer surface of insulation is at 28°C, calculate the heat loss (in watts) for 15 m of pipe.
Hot engine oil is being transported in a horizontal pipe (k = 15 W/m∙K, Di = 5 cm) with a wall thickness of 5 mm. The pipe is covered with a 5-mm-thick layer of insulation (k = 0.15 W/m∙K). A length of 2 m of the outer surface is exposed to cool air at 10°C. If the pipe inner surface temperature is at 90°C, determine the outer surface temperature. Hint: The pipe outer surface temperature has to be found iteratively. Begin the calculations by using a film temperature of 50°C.
Question 1: A glass window of width W = 1 m and height H = 2m is 5 mm thick and has a thermal conductivity of kg =1.4 W/m.K. If the inner and outer surface temperatures of the glass are 15 °C and -20 C, respectively, on a cold winter day, what is the rate of heat loss through the glass? To reduce heat loss through windows, it is customary to use a double pane construction in which adjoining panes are separated by an air space. If the spacing is 10 mm and the glass surfaces in contact with the air have temperatures of (last two digit of your Registration number) °C and -15 °C, what is the rate of heat loss from a 1 mx2mwindow? The thermal conductivity of air is ka = 0.024 W/m.K.
A glass window of width W = 1 m and height H = 2 m is 5 mm thick and has a thermal conductivity of kg =1.4 W/m.K. If the inner and outer surface temperatures of the glass are 15 oC and -20 oC, respectively, on a cold winter day, what is the rate of heat loss through the glass? To reduce heat loss through windows, it is customary to use a double pane construction in which adjoining panes are separated by an air space. If the spacing is 10 mm and the glass surfaces in contact with the air have temperatures of 9oC and -15 oC, what is the rate of heat loss from a 1 m x 2 m window? The thermal conductivity of air is ka = 0.024 W/m.K.