Question 1: In your own words, write down the differences between thermodynamic and heat transfer. (3 Marks) Question 2: Estimate the heat loss per square metre of surface through a brick wall 0.5 m thick when the inner surface is at 400 K and the outside surface is at 300 K. The thermal conductivity of the brick may be taken as 0.7 W/mK. (2 Marks) Question 3: A furnace is constructed with 0.20 m of firebrick, 0.10 m of insulating brick, and 0.20 m of building brick. The inside temperature is 1200 K and the outside temperature is 330 K. If the thermal conductivities are as shown in the figure below, estimate the heat loss per unit area. (5 Marks) 1200 K 330 K Insulating brick Ordinary brick Fire brick X-0.20 m x-0.10m x-0.20 m k= 1.4 K3D0.21 k= 0.7 (Wimk)

Question 1: In your own words, write down the differences between thermodynamic and heat transfer. (3 Marks) Question 2: Estimate the heat loss per square metre of surface through a brick wall 0.5 m thick when the inner surface is at 400 K and the outside surface is at 300 K. The thermal conductivity of the brick may be taken as 0.7 W/mK. (2 Marks) Question 3: A furnace is constructed with 0.20 m of firebrick, 0.10 m of insulating brick, and 0.20 m of building brick. The inside temperature is 1200 K and the outside temperature is 330 K. If the thermal conductivities are as shown in the figure below, estimate the heat loss per unit area. (5 Marks) 1200 K 330 K Insulating brick Ordinary brick Fire brick X-0.20 m x-0.10m x-0.20 m k= 1.4 K3D0.21 k= 0.7 (Wimk)

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.

Chapter2: Steady Heat Conduction

Section: Chapter Questions

Problem 2.6P: A plane wall of thickness 2L has internal heat sources whose strength varies according to...

See similar textbooks

Similar questions

1.3 A furnace wall is to be constructed of brick having standard dimensions of Two kinds of material are available. One has a maximum usable temperature of 1040°C and a thermal conductivity of 1.7 W/(m K), and the other has a maximum temperature limit of 870°C and a thermal conductivity of 0.85 W/(m K). The bricks have the same cost and are laid in any manner, but we wish to design the most economical wall for a furnace with a temperature of 1040°C on the hot side and 200°C on the cold side. If the maximum amount of heat transfer permissible is 950 , determine the most economical arrangement using the available bricks.
A plane wall of thickness 2L has internal heat sources whose strength varies according to qG=qocos(ax) Where qo is the heat generated per unit volume at the center of the wall (x=0) and a is a constant. If both sides of the wall are maintained at a constant temperature of Tw, derive an expression for the total heat loss from the wall per unit surface area.
Discuss the modes of heat transfer that determine the equilibrium temperature of the space shuttle Endeavour when it is in orbit. What happens when it reenters the earths atmosphere?
1.63 Liquid oxygen (LOX) for the space shuttle is stored at 90 K prior to launch in a spherical container 4 m in diameter. To reduce the loss of oxygen, the sphere is insulated with superinsulation developed at the U.S. National Institute of Standards and Technology's Cryogenic Division; the superinsulation has an effective thermal conductivity of 0.00012 W/m K. If the outside temperature is on the average and the LOX has a heat of vaporization of 213 J/g, calculate the thickness of insulation required to keep the LOX evaporation rate below 200 g/h.
As a designer working for a major electric appliance manufacturer, you are required to estimate the amount of fiberglass insulation packing (k = 0.035 W/m K) that is needed for a kitchen oven shown in the figure below. The fiberglass layer is to be sandwiched between a 2-mm-thick aluminum cladding plate on the outside and a 5-mm-thick stainless steel plate on the inside that forms the core of the oven. The insulation thickness is such that the outside cladding temperature does not exceed 40C when the temperature at the inside surface of the oven is 300C. Also, the air temperature in the kitchen varies from 15Cto33C, and the average heat transfer coefficient between the outer surface of the oven and air is estimated to be 12.0W/m2K. Determine the thickness of the fiberglass insulation that is required for these conditions. What would be the outer surface temperature when the inside surface of the oven is at 475C?
5.10 Experiments have been performed on the temperature distribution in a homogeneous long cylinder (0.1 m diameter, thermal conductivity of 0.2 W/m K) with uniform internal heat generation. By dimensional analysis, determine the relation between the steady-state temperature at the center of the cylinder , the diameter, the thermal conductivity, and the rate of heat generation. Take the temperature at the surface as your datum. What is the equation for the center temperature if the difference between center and surface temperature is when the heat generation is ?
Using Table 1.4 as a guide, prepare a similar table showing the orders of magnitude of the thermal resistances of a unit area for convection between a surface and various fluids.
show schematic drawings, conversions, units and box in your final answers A furnace wall is made up of three layer of thickness 200 mm, 100 mm, and 125 mm with thermal conductivity of 1.65 W/m-K, k2, and 9.2 W/m-K respectively. The inside is exposed to gases at 1200°C with a convection coefficient of 25 W/m²-K and the inside surface temperature is at 1000°C, the outside air temperature is at 30°C with convection coefficient of 12 W/m²-K. Calculate: a. the unknown thermal conductivity; b. the outside surface temperature and mid-plane temperatures in °F.
1/ 1 100% + T7 Heat Transfer & Applications Q1. The heat flux through a wood slab 50 mm thick, whose inner and outer surface temperatures are 40 and 20°C respectively has been determined to be 40 W/m2. What is the thermal conductivity of the wood. (0.1 W/ mK) o uindow 5 mm thick are
A brick wall, 500 mm thick and having a thermal conductivity of 0.75 W/(m K), measures 15 m long by 4 m high, and has a temperature difference between the inside and outside faces of 20 K. What is the rate of heat conduction
1) "Two-by-four" wood studs have actual dimensions of 4. 13 x 9.21 cm and a thermal conductivity of 0.1 W/m. °C. A typical wall for a house is constructed as shown below. Calculate: a) heat transfer rate through the wall, b) temperature of inside wall, outside wall, and insulation material; and (c) temperature drop across common brick. Disregard any contact resistances at interfaces. Outside air convection, h = 15 W/m?. °C Common brick, k= 0.69 8 cm 1.9 cm, k = 0.96 Gypsum sheath 1.9 cm. k= 048 40.6 cm Insulation, k = 0.04 2 x 4 studs Inside air convection, h= 7.5 W/m²• C
2. In determining the thermal conductivity of a plateflat insulator, the temperature was measured on both sides of the 25 mm thick plate and gave the results of 318.4 K and 303.2 K. FluxThe measured heat is 35.1 W.m-2. Illustrate the problem in a simple schematic/drawing, then calculate the thermal conductivity inbtu/h.ft.oF and in W/m.K! (0.033 ; 0.058) 3. A coil-shaped cooling pipe is made of SS-304 material. This pipe is 1 ft long, 0.4 inch outside diameter, and inch inside diameter. This coil cooling pipe is used to cool the water in the bath. The temperature of the inner coil pipe is 40oF while the outer coil in contact with water is 80oF. The thermal conductivity of SS-304 is a function of temperature where k(T) = 7.75 + (7.78 x 10-3).T where k is in Btu/h.ft.oF and T is in oF. Calculate the rate of heat dissipation in watts! (1287.7)