System Dynamics
3rd Edition
ISBN: 9780077509125
Author: Palm
Publisher: MCG
expand_more
expand_more
format_list_bulleted
Concept explainers
Textbook Question
Chapter 7, Problem 7.49P
A certain wall section is composed of a 12 in. by 12 in. brick area 4 in. thick. Surrounding the brick is a 36 in. by 36 in. concrete section, which is also 4 in. thick. The thermal conductivity of the brick is k = 0.086 lb/sec-°F.
For the concrete, k — 0.02 lb/sec-°F. (a) Determine the thermal resistance of the wall section, (b) Compute the heat flowr rate through (1) the concrete,
(2) the brick, and (3) the wall section if the temperature difference across the wall is 40°F.
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solutionStudents have asked these similar questions
The walls of the flat furnace are connected by two insulating layers A and B. The temperature of the insulating layer A facing the inside of the Furnace is 800°C and the temperature of the outside air is 60°C. Find the temperature of the interface between the two insulation layers when the thickness of insulation layer A is 150 mm, its thermal conductivity is 0.05 W/m℃, the thickness of insulation layer B is 240 mm, and its thermal conductivity is 0.15 W/m℃
5. A 10-in nominal pipe (outside diameter = 10.75in) is covered with a composite pipe insulation consisting of 2.0 in of insulation I placed next to the pipe and 1.5 in of insulation II placed upon insulation I. Assume that the inner and outer surface temperatures of the composite insulation are 900F and 150F respectively, and that the thermal conductivity of material I is 0.05 BTU/hr-ft-F and for material II is 0.039 BTU/hr-ft-F. What is the individual thermal resistance of insulation I?
A 1 in. o.d. (outer diameter) tube reactor is insulated with a 3 inch layer of asbestos. If the temperature of the outer surface of the insulation is 100 °F and the rate of heat loss per foot of reactor length is 50 BTU/hr, what must the temperature of the inside of the reactor be? [for asbestos, k = 0.105 BTU/hr ft °F]
Chapter 7 Solutions
System Dynamics
Ch. 7 - Prob. 7.1PCh. 7 - Refer to the water storage and supply system shown...Ch. 7 - Prob. 7.3PCh. 7 - In Figure P7.4 the piston of area A is connected...Ch. 7 - Refer to Figure 7.1.4a. and suppose that p\ — p2=...Ch. 7 - Pure water flows into a mixing tank of volume V =...Ch. 7 - Consider the mixing tank treated in Problem 7.6....Ch. 7 - Derive the expression for the fluid capacitance of...Ch. 7 - Prob. 7.9PCh. 7 - Prob. 7.10P
Ch. 7 - 7.11 Derive the expression for the capacitance of...Ch. 7 - Air flows in a certain cylindrical pipe 1 m long...Ch. 7 - Derive the expression for the linearized...Ch. 7 - Consider the cylindrical container treated in...Ch. 7 - A certain tank has a bottom area A = 20 m2. The...Ch. 7 - A certain tank has a circular bottom area A = 20...Ch. 7 - The water inflow rate to a certain tank was kept...Ch. 7 - Prob. 7.18PCh. 7 - Prob. 7.19PCh. 7 - In the liquid level system shown in Figure P7.20,...Ch. 7 - The water height in a certain tank was measured at...Ch. 7 - Derive the model for the system shown in Figure...Ch. 7 - (a) Develop a model of the two liquid heights in...Ch. 7 - Prob. 7.24PCh. 7 - Design a piston-type damper using an oil with a...Ch. 7 - Prob. 7.26PCh. 7 - 7.27 An electric motor is sometimes used to move...Ch. 7 - Prob. 7.28PCh. 7 - Prob. 7.29PCh. 7 - Figure P7.3O shows an example of a hydraulic...Ch. 7 - Prob. 7.31PCh. 7 - Prob. 7.32PCh. 7 - Prob. 7.33PCh. 7 - Prob. 7.34PCh. 7 - Prob. 7.35PCh. 7 - Prob. 7.36PCh. 7 - Prob. 7.37PCh. 7 - (a) Determine the capacitance of a spherical tank...Ch. 7 - Obtain the dynamic model of the liquid height It...Ch. 7 - Prob. 7.40PCh. 7 - Prob. 7.41PCh. 7 - Prob. 7.42PCh. 7 - Prob. 7.43PCh. 7 - Prob. 7.44PCh. 7 - Prob. 7.45PCh. 7 - The copper shaft shown in Figure P7.46 consists of...Ch. 7 - A certain radiator wall is made of copper with a...Ch. 7 - A particular house wall consists of three layers...Ch. 7 - A certain wall section is composed of a 12 in. by...Ch. 7 - Prob. 7.50PCh. 7 - Prob. 7.51PCh. 7 - A steel tank filled with water has a volume of...Ch. 7 - Prob. 7.53PCh. 7 - Prob. 7.54PCh. 7 - Prob. 7.55P
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.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.arrow_forward1.10 A heat flux meter at the outer (cold) wall of a concrete building indicates that the heat loss through a wall of 10-cm thickness is . If a thermocouple at the inner surface of the wall indicates a temperature of 22°C while another at the outer surface shows 6°C, calculate the thermal conductivity of the concrete and compare your result with the value in Appendix 2, Table 11.arrow_forward1.37 Mild steel nails were driven through a solid wood wall consisting of two layers, each 2.5-cm thick, for reinforcement. If the total cross-sectional area of the nails is 0.5% of the wall area, determine the unit thermal conductance of the composite wall and the percent of the total heat flow that passes through the nails when the temperature difference across the wall is 25°C. Neglect contact resistance between the wood layers.arrow_forward
- 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 1.4arrow_forwardAnswer within 10 minutes : The temperature at the inside surface of an oven is 460 oF. The inside wall of the oven is made of brick and is 8 inch thick. The thermal conductivity of the brick is 2.2 Btu/hr.ft2.(oF/ft). The outside of the oven is covered with a 3-inch layer of asbestos as insulation, which has a thermal conductivity of 0.11 Btu/hr.ft2.(oF/ft). If the outer surface of the insulation has a temperature of 100 oF , calculate the amount of heat lost through 2 ft2 of wall area in 3 hours.arrow_forwardA hollow cylindrical insulation of inside diameter 0.2 m and outside diameter 0.4 m conducts heat radially. If another layer of insulation of the same material of thickness of 0.4 m is added, the heat flow will be changed by what ratio?arrow_forward
- Calculate the heat loss per foot from a 10 in. nominal pipe ( outside diameter = 10.75 in.) covered with a composite pipe insulation consisting of 1 ½ in of insulation A placed next to the pipe and 2 in. of insulation B placed upon insulation A. Assume that the inner and outer surface temperature of the composite insulation are 700°F and 110°F respectively , and that the thermal conductivity of material I is 0.05 Btu/ hr-ft-°F and for material II is 0.039 Btu/hr-ft-°F (Include illustration/Figure)arrow_forwardAn exterior wall of a house may be approximated by a 4-in layer of common brick [k =0.7 W/m · ◦C] followed by a 1.5-in layer of gypsum plaster [k = 0.48 W/m · ◦C]. What thickness of loosely packed rock-wool insulation [k = 0.065 W/m · ◦C] should be added to reduce the heat loss (or gain) through the wall by 80 percent?arrow_forwardTwo plates, one of aluminum with a tickness of 14mm and one of brass with thickness of 9mm were attached to each other. Determine the thickness of a board of another metallic material with thermal conductivity λ= 79W / mK so that it conducts an equal heat flow as together fasten the boards at the same total temperature drop across the structure. The thermal conductivity for aluminium is λAI = 238W / mK and for brass λm = 111W / mK.arrow_forward
- A flat wall is exposed to the environment. The wall is covered with a layer of insulation 1.0 inches thick whose thermal conductivity is 0.8 Btu/h*ft²*°F. The temperature of the wall on the inside of the insulation is 600°F. The wall loses heat to the environment by convection on the surface of the insulation. The average value of the convection heat transfer coefficient on the insulation surface is 950 Btu/h*ft²*°F. Compute the bulk temperature of the environment (Tb) if the outer surface of the insulation does not exceed 105°F.arrow_forwardA steel pipe (outside diameter 100 mm) is covered with two layers of insulation. The inside layer, 40 mm thick, has a thermal conductivity of 0.07 W/(m K). The outside layer, 20 mm thick, has a thermal conductivity of 0.15 W/(m K). The pipe is used to convey steam at a pressure of 600 kPa. The outside temperature of insulation is 24°C. If the pipe is 10 m long, determine the following, assuming the resistance to conductive heat transfer in steel pipe and convective resistance on the steam side are negligible: a. The heat loss per hour. b. The interface temperature of insulation.arrow_forwardIn a glass plant in Cavite, a furnace has fire-brick walls made up of the following two materials in series : Non-corrosive brick as inner layer (material 1) Clay brick as outer layer (material 2) Thickness 4.5 inches 8 inches Thermal conductivity k1 k2 The temperature inside the furnace (inside wall surface of the non-corrosive brick) is found to be 1105 oF while the outside temperature (outside wall surface of clay brick) is 365 oF. This is not the desired temperature inside the furnace so engineers thought of lagging the furnace walls with another material to reduce heat loss. The additional lagging material consists of magnesia layer which is 2 inches thick and has a thermal conductivity of 0.04 Btu /h.ft.oF. During a test run on the furnace with the magnesia lagging material now, new temperature readings were recorded : Point of measurement Temperature reading Inside furnace (inside wall surface of non-corrosive brick 1355 oF Interface between…arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning
Principles of Heat Transfer (Activate Learning wi...
Mechanical Engineering
ISBN:9781305387102
Author:Kreith, Frank; Manglik, Raj M.
Publisher:Cengage Learning
Understanding Conduction and the Heat Equation; Author: The Efficient Engineer;https://www.youtube.com/watch?v=6jQsLAqrZGQ;License: Standard youtube license