Heat and Mass Transfer: Fundamentals and Applications
5th Edition
ISBN: 9780073398181
Author: Yunus A. Cengel Dr., Afshin J. Ghajar
Publisher: McGraw-Hill Education
expand_more
expand_more
format_list_bulleted
Concept explainers
Videos
Textbook Question
Chapter 3, Problem 100CP
A pipe is insulated such that the outer radius of the insulation is less than the critical radius. Now the insulation is taken off. Will the rate of heat transfer from the pipe increase or decrease for the same pipe surface temperature?
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
A steam pipe, made of copper, has an inside diameter of 5 cm and an outside diameter of 6.2 cm. To reduce thermal loss to the surroundings, the pipe is insulated with 2.55 cm thick fiberglass. An aluminum foil of a thickness of 0.2 mm covers the insulation. Find the rate of heat loss from the pipe using the following data: hi = 142 W/m K, Ti = 150 C, ho = 68 W/m K, To = 27C, Lpipe = 98.5 m. [Ans.: 0.43 kW].
A metal furnace with a 1.25 m x 0.75 m metal door is placed in a room and set to 400K. A 0.3 m x 0.3 m glass window is located in the furnace door. The thickness of the metal alloy and the glass window are 3 mm and 2 mm, respectively. The glass window has a thermal conductivity (k) of 0.7 W/m .K and the metal door has a thermal conductivity (k) of 3.5 W/m.K. The convective heat coefficient hi and ho on each site of the furnace door is estimated as 10W/m2.K. Assuming the room temperature is held constant at 297 K, calculate the total heat loss from the furnace door.
P.S Could you write the solution clearly to better understanding? Step by step using formulas. Another page with detailed steps would be better. Thanks in advance.
The oven of a stove must have a sufficient insulation so that the surface temperature of the stove is not greater than 50 oC. To accomplish this, insulation, k = 0.11 W/m-K, is used between the inside and outside metal surfaces. The room temperature is 20 oC, and the outside unit convective coefficient is 8 W/m2-K. Neglecting the resistance of the metal, what is the minimum thickness of insulation required, if the outside temperature reaches 315 oC?
Chapter 3 Solutions
Heat and Mass Transfer: Fundamentals and Applications
Ch. 3 - Consider heat conduction through a wall of...Ch. 3 - Consider heat conduction through a plane wall....Ch. 3 - What does the thermal resistance of a medium...Ch. 3 - Can we defme the convection resistance for a unit...Ch. 3 - Consider steady heat transfer through the wall of...Ch. 3 - How is the combined heat transfer coefficient...Ch. 3 - Why are the convection and the radiation...Ch. 3 - Consider steady one-dimensional heat transfer...Ch. 3 - Someone comments that a microwave oven can be...Ch. 3 - Consider two cold canned drinks, one wrapped in a...
Ch. 3 - The bottom of a pan is made of a 4-mm-thick...Ch. 3 - Consider a surface of area A at which the...Ch. 3 - How does the thermal resistance network associated...Ch. 3 - Consider steady one-dimensional heat transfer...Ch. 3 - Consider a window glass consisting of two...Ch. 3 - Prob. 16PCh. 3 - Consider a person standing in a room at 20C with...Ch. 3 - Consider an electrically heated brick house...Ch. 3 - A12-cm18-cm circuit board houses on its surface...Ch. 3 - Water is boiling in a 25-cm-diameter aluminum pan...Ch. 3 - A cylindrical resistor element on a circuit board...Ch. 3 - Prob. 22PCh. 3 - A1.0m1.5m double-pane window consists of two...Ch. 3 - Prob. 24PCh. 3 - Prob. 25PCh. 3 - Prob. 26PCh. 3 - Prob. 27PCh. 3 - Prob. 28EPCh. 3 - To defog the rear window of an automobile, a very...Ch. 3 - A transparent film is to be bonded onto the top...Ch. 3 - To defrost ice accumulated on the outer surface of...Ch. 3 - Prob. 32PCh. 3 - Prob. 33PCh. 3 - Prob. 34PCh. 3 - Prob. 35PCh. 3 - Prob. 36PCh. 3 - Heat is to be conducted along a circuit board that...Ch. 3 - Prob. 38EPCh. 3 - Consider a house that has a 10m20-m base and a...Ch. 3 - Prob. 40EPCh. 3 - Prob. 41PCh. 3 - Prob. 42PCh. 3 - What is thermal contact resistance? How is it...Ch. 3 - Will the thermal contact resistance be greater for...Ch. 3 - Explain how the thermal contact resistance can be...Ch. 3 - A waII consists of two layers of insulation...Ch. 3 - Prob. 47CPCh. 3 - Consider two surfaces pressed against each other....Ch. 3 - Prob. 49PCh. 3 - Two 5-cm-diameter, 15-cm-long aluminum bars...Ch. 3 - Prob. 51PCh. 3 - Two identical aluminum plates with thickness of 30...Ch. 3 - A tvolayer wall is made of two metal plates, with...Ch. 3 - An aluminum plate and a stainless steel plate are...Ch. 3 - Prob. 55PCh. 3 - Prob. 56PCh. 3 - Prob. 57PCh. 3 - What are the two approaches used in the...Ch. 3 - The thermal resistance networks can also be used...Ch. 3 - When plotting the thermal resistance network...Ch. 3 - A 10-cm-thick vall is to be constructed with...Ch. 3 - Prob. 62EPCh. 3 - Prob. 63PCh. 3 - Prob. 64PCh. 3 - Prob. 65PCh. 3 - Prob. 66PCh. 3 - Prob. 67PCh. 3 - Prob. 68PCh. 3 - A 12-m-long and 5-m-high wall is constructed of...Ch. 3 - Prob. 70EPCh. 3 - Prob. 71PCh. 3 - Prob. 72PCh. 3 - What is an infinitely long cylinder? When is it...Ch. 3 - Can the thermal resistance concept be used for a...Ch. 3 - Consider a short cylinder whose top and bottom...Ch. 3 - Prob. 76PCh. 3 - Prob. 77PCh. 3 - Prob. 78PCh. 3 - Superheated steam at an average temperature 20C is...Ch. 3 - Prob. 80EPCh. 3 - Prob. 81EPCh. 3 - Prob. 82PCh. 3 - Prob. 83PCh. 3 - Prob. 84PCh. 3 - Prob. 85PCh. 3 - Prob. 86EPCh. 3 - Prob. 87PCh. 3 - Prob. 88PCh. 3 - Liquid hydrogen is flowing through an insulated...Ch. 3 - Exposure to high concentrations of gaseous ammonia...Ch. 3 - A mixture of chemicals is flowing in a pipe...Ch. 3 - Ice slurry is being transported in a pipe...Ch. 3 - Prob. 93PCh. 3 - Prob. 94PCh. 3 - Prob. 95PCh. 3 - What is the critical radius of insulation? How is...Ch. 3 - Prob. 97CPCh. 3 - Prob. 98CPCh. 3 - Prob. 99CPCh. 3 - A pipe is insulated such that the outer radius of...Ch. 3 - A 0.083-in-diameter electrical wire at 90F is...Ch. 3 - Repeat Prob. 3-109E, assuming a thermal contact...Ch. 3 - Prob. 103PCh. 3 - Prob. 104PCh. 3 - Hot air is to be cooled as it is forced to flow...Ch. 3 - Prob. 106CPCh. 3 - Prob. 107CPCh. 3 - The fins attached to a surface are determined to...Ch. 3 - Explain how the fins enhance heat transfer from a...Ch. 3 - How does the overall effectiveness of a finned...Ch. 3 - Hot water is to be cooled as it flows through the...Ch. 3 - Consider two finned surfaces that are identical...Ch. 3 - The heat transfer surface area of a fin is equal...Ch. 3 - Does the (a) efficiency and (b) effectiveness of a...Ch. 3 - Two pin fins are identical, except that the...Ch. 3 - Two plate fins of constant rectangular cross...Ch. 3 - Two finned surfaces are identical, except that the...Ch. 3 - Obtain a relation for the fin efficiency for a fin...Ch. 3 - Prob. 119PCh. 3 - Consider a very long rectangular fin attached to a...Ch. 3 - Prob. 121PCh. 3 - Prob. 122EPCh. 3 - Prob. 123EPCh. 3 - Prob. 124PCh. 3 - Prob. 125PCh. 3 - Prob. 126PCh. 3 - Prob. 127PCh. 3 - Prob. 128PCh. 3 - Prob. 129PCh. 3 - Prob. 130PCh. 3 - Prob. 131PCh. 3 - Prob. 132PCh. 3 - Prob. 133PCh. 3 - Prob. 134PCh. 3 - The human body is adaptable to extreme climatic...Ch. 3 - Consider the conditions of Example 3-14 in the...Ch. 3 - Consider the conditions of Example 3-14 in the...Ch. 3 - Prob. 138PCh. 3 - What is a conduction shape factor? How is it...Ch. 3 - What is the value of conduction shape factors in...Ch. 3 - Prob. 141PCh. 3 - A thin-walled cylindrical container is placed...Ch. 3 - Prob. 143PCh. 3 - Prob. 144PCh. 3 - Prob. 145PCh. 3 - Prob. 146EPCh. 3 - Prob. 147PCh. 3 - Prob. 148PCh. 3 - Prob. 149PCh. 3 - Prob. 150PCh. 3 - Prob. 151PCh. 3 - Prob. 152PCh. 3 - Consider a house with a flat roof whose outer...Ch. 3 - Prob. 154PCh. 3 - Radioactive material, stored in a spherical vessel...Ch. 3 - What is the R-value of a wall? How does it differ...Ch. 3 - What is effective emissivity for a plane-parallel...Ch. 3 - Prob. 158CPCh. 3 - What is a radiant barrier? What kinds of materials...Ch. 3 - Consider a house whose attic space is ventilated...Ch. 3 - Prob. 161PCh. 3 - Prob. 162PCh. 3 - Prob. 163PCh. 3 - Prob. 164PCh. 3 - Prob. 165PCh. 3 - Prob. 166PCh. 3 - Determine the winter R-value and the U-factor of a...Ch. 3 - The overall heat transfer coefficient (the...Ch. 3 - Prob. 169EPCh. 3 - Determine the summer and winter R-values. in m2 ....Ch. 3 - The overall heat transfer coefficient of a wall is...Ch. 3 - Two homes are identical, except that the walls of...Ch. 3 - Prob. 173PCh. 3 - Consider two identical people each generating 60 V...Ch. 3 - Cold conditioned air at 12C is flowing inside a...Ch. 3 - Hot water is flowing at an average velocity of 1.5...Ch. 3 - Prob. 177PCh. 3 - Prob. 178PCh. 3 - Prob. 179PCh. 3 - Prob. 180PCh. 3 - Prob. 181PCh. 3 - Prob. 182PCh. 3 - Prob. 183PCh. 3 - Prob. 184PCh. 3 - Prob. 185PCh. 3 - A total of 10 rectangular aluminum fins...Ch. 3 - Prob. 187PCh. 3 - A plane wall surface at 200C is to be cooled with...Ch. 3 - Prob. 189PCh. 3 - Prob. 190PCh. 3 - Prob. 191PCh. 3 - Prob. 192PCh. 3 - A 0.6-rn-diameter, 1.9-rn-long cylindrical tank...Ch. 3 - Prob. 194PCh. 3 - Prob. 195PCh. 3 - A thin-walled spherical tank is buried in the...Ch. 3 - Heat is lost at a rate of 275 W per m2 area of a 1...Ch. 3 - Prob. 198PCh. 3 - Heat is generated steadily in a 3-cm-diameter...Ch. 3 - Prob. 200PCh. 3 - Prob. 201PCh. 3 - Prob. 202PCh. 3 - Prob. 203PCh. 3 - Prob. 204PCh. 3 - Consider two walls. A and B, with the same surface...Ch. 3 - Prob. 206PCh. 3 - A room at 20C air temperature is losing heat to...Ch. 3 - Prob. 208PCh. 3 - A 1-cm-diameter, 30cm-long fin made of aluminum...Ch. 3 - A hot surface at 80C in air at 20C is to be cooled...Ch. 3 - A cylindrical pin fin of diameter 0.6 cm and...Ch. 3 - A 3-cm-long. 2-nuti x 2-mm rectangular...Ch. 3 - Two finned surfaces with long fins are identical,...Ch. 3 - A 20-cm-diameter hot sphere at 120C is buried in...Ch. 3 - A 25-cm-diameter, 2.4-rn-long vertical cylinder...Ch. 3 - Prob. 216PCh. 3 - The walls of a food storage facility are made of a...Ch. 3 - The equivalent thermal resistance for the thermal...Ch. 3 - Prob. 219PCh. 3 - Prob. 220PCh. 3 - Prob. 221PCh. 3 - The fin efficiency is defined as the ratio of the...Ch. 3 - Prob. 223PCh. 3 - In the United States, building insulation is...Ch. 3 - Prob. 225PCh. 3 - A plane brick wall (k=0.7W/m.K) and is 10 cm...Ch. 3 - The temperature in deep space is close to absolute...Ch. 3 - In the design of electronic components, it is...Ch. 3 - Using cylindrical samples of the same material,...Ch. 3 - Find out about the wall construction of the cabins...Ch. 3 - Prob. 231PCh. 3 - A house with 200-m2 floor space is to be heated...
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
- (b) A hydrogen gas cylinder is situated in the cylinder cage. The cylinder wall is constructed from 15.5 mm carbon fiber (kcp = 0.75 W mK-¹). The outside of the cylinder is lagged with an inner 10 mm layer of ceramic insulation (kc = 0.08 W mK-¹) and an outer 80 mm layer of fiberglass insulation (kp = 0.15 W mK-¹). The temperature on the hydrogen gas is 150 °C and the temperature of the cylinder cage is 45 °C. Given that the walls of the cylinder can be assumed to be flat and neglecting the contribution of radiation, calculate: (i) the heat flux per square meter of the gas cylinder wall (ii) the temperature at the interface between the fibreglass and the ceramic insulation. 1.1arrow_forwardIt is designed in such a way that the internal temperature of a commercial heat treatment furnace can reach up to 165 oC. All surfaces of the furnace consist of firebrick (10 cm), insulation material and sheet metal (3mm) from the inside out. Given that the outdoor temperature is 22 oC, the outer sheet will be allowed to go up to 35 oC, which is a temperature that will not be disturbed by hand contact. In this case, determine the insulation material thickness to be used. Insulation material thermal conductivity coefficient is 0.066 insulation W / m oC, 60 W / m oC for sheet metal and 115 W / m oC for firebrick. Indoor heat transfer coefficient will be accepted as 25 W / m2 oC and 12 W / m2 oC for outdoor environment.arrow_forwardTwo long rods of the same diameter, one of brass(k= 85 W/mK) and the other of copper (k=375 W/mK) have one of their ends inserted in a furnace and the other ends exposed to the same atmosphere. At a distance of 105mm away from the furnace, the temperature of the brass rod is 120 C. Find the distance form the furnace in which the copper rod have the same temperaturearrow_forward
- A silicon wafer with thickness of 925 µm is being heated with a uniform heat flux at the lower surface. The silicon wafer has a thermal conductivity that varies with temperature and can be expressed as k(T) = (a + bT + cT2) W/m·K, where a = 450, b = -1.29, and c = 0.00111. To avoid warping, the temperature difference across the wafer thickness cannot exceed 2°C. If the upper surface of the silicon wafer is at a uniform temperature of 600 K, determine the maximum allowable heat flux. (Round your answer up to 2 decimal places.)arrow_forwardCalculate the heat loss through a 100-ft² wall with an inside temperature of 65°F and an outside temperature of 35°F. Assume the exterior wall is composed of 2- in. of material having a 'k' factor of 0.80, and 2-in. of insulation having a conductance of 0.16. RTotal = 8.75 & Q = 342-Btu/hr RTotal = 9.2 & Q = 399-Btu/hr RTotal = 8.75 & Q = 399-Btu/hr RTotal = 9.2 & Q = 342-Btu/hr Hide hint for Question 3 Utilize the (RTotal = 1/C + x1/k1) equation.arrow_forwardQuestion 4 The window of a room is made of 5 mm thick glass which has a thermal conductivity of 1.4 W/m-K. A heater is used to maintain the room temperature at 22 °C. Take the convection heat transfer coefficients on the outer surface of the window to be 12 W/m²-K. Take appropriate assumptions while solving this problem. (a) T₁=15°C TA -A- 1m x 3m = 3m², k=1.4W/m-K -T₂=5°C L=0.005m Figure Q2 Determine the heater thermal load to maintain the room temperature?arrow_forward
- Two large stainless steel plates at temperatures of 90°C and 70°C are separated by a stainless steel rod0.3 m long and 2.5 cm in diameter. The thermal conductivity of type 304 stainless steel is k = 16.2W/m K. The rod is welded to each plate. The space between the plates is filled with insulation so thatno heat is lost from the circumference of the rod. Because of a voltage difference between the twoplates, current flows through the rod, resulting in a uniform heat generation rate of 1.5 x 105 W/m3.a) Solve for the temperature distribution in the rod as a function of position x analytically (integratethe equation).b) Determine the maximum temperature in the rod. Where does it occur?c) Solve for the temperature distribution in the rod as a function of position x using the finitedifference method. Assume a ∆x of 0.05 m. How does this compare to the exact solution?arrow_forwarddetermine the rate of heat transfer through the wall in Watts and the temperature at the inner and outer surfaces and at the interfaces. k = 0.20 W/m-°C for the 2.5 cm thick plaster wall on the inside k = 0.038 W/m-ºC for the 9.0 cm thick fiberglass insulation layer k = 0.12 W/m-°C for the 1.25 cm plywood layer on the outside. Assume: -the inside room air is 20 °C with convection coefficient of 10 W/m²- ºC, and - the outside air at -20 °C with convection coefficient of 20 W/m²-°C. Plaster Wall Insulation 12 2.5 cm 9 cm Plywood outside 34 k -1.25 cmarrow_forwardVariation of the surface temperature of a pin fin is shown in the Figure. According to the figure, the following statements are made. 1-Fin is insulated perfectly. 2-The fin is in an environment with a temperature of 80 °C. 3-The efficiency of the fin is 1. 4-The heat conduction at the base of the fin is not higher than that of the tip. 5-The heat conduction at the middle of the pin is zero. Choose the correct option. 80°C 80 80 80 80°C O a. 3, 4 and 5 are correct, the rest are wrong O b. 4 and 5 are wrong, the rest are true O c. All statements are correct O d. 1 and 2 are correct, the rest are wrong O e. 4 is wrong, the rest are correctarrow_forward
- a pipe with an outside diameter of 2.5 inches is insulated with 2 inches layer of asbestos ( K= 0.396(btu-in)/(hr-ft-F) followed by a layer of cork 1.5 inches thick ( K= 0.30 (btu-in)/ft (hr-ft-F). if the temperature of the outer surface of the cork and pipe is 90 F and 290 F RESPECTIVELY, calculate the heat loss per 100 ft of insulated pipe in btu/hrarrow_forwardWhy does heat transfer increase initially with radius of insulation and then decrease beyond critical radius? Explain in details.arrow_forwardA composite wall layer consists of layer A covered by layer B. The thermal resistance of layer A is 0.75 °C/W and the thermal resistance of layer B is 2.50 °C/W. The exposed surface of layer A is at a temperature of 60°C. If the heat transfer per unit area across the composite wall is 30 W/m?, what is the temperature at the interface between layer A and layer B? Express your answer in °C.arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Elements Of ElectromagneticsMechanical EngineeringISBN:9780190698614Author:Sadiku, Matthew N. O.Publisher:Oxford University Press
Mechanics of Materials (10th Edition)Mechanical EngineeringISBN:9780134319650Author:Russell C. HibbelerPublisher:PEARSON
Thermodynamics: An Engineering ApproachMechanical EngineeringISBN:9781259822674Author:Yunus A. Cengel Dr., Michael A. BolesPublisher:McGraw-Hill Education
Control Systems EngineeringMechanical EngineeringISBN:9781118170519Author:Norman S. NisePublisher:WILEY
Mechanics of Materials (MindTap Course List)Mechanical EngineeringISBN:9781337093347Author:Barry J. Goodno, James M. GerePublisher:Cengage Learning
Engineering Mechanics: StaticsMechanical EngineeringISBN:9781118807330Author:James L. Meriam, L. G. Kraige, J. N. BoltonPublisher:WILEY
Elements Of Electromagnetics
Mechanical Engineering
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Oxford University Press
Mechanics of Materials (10th Edition)
Mechanical Engineering
ISBN:9780134319650
Author:Russell C. Hibbeler
Publisher:PEARSON
Thermodynamics: An Engineering Approach
Mechanical Engineering
ISBN:9781259822674
Author:Yunus A. Cengel Dr., Michael A. Boles
Publisher:McGraw-Hill Education
Control Systems Engineering
Mechanical Engineering
ISBN:9781118170519
Author:Norman S. Nise
Publisher:WILEY
Mechanics of Materials (MindTap Course List)
Mechanical Engineering
ISBN:9781337093347
Author:Barry J. Goodno, James M. Gere
Publisher:Cengage Learning
Engineering Mechanics: Statics
Mechanical Engineering
ISBN:9781118807330
Author:James L. Meriam, L. G. Kraige, J. N. Bolton
Publisher:WILEY
Understanding Conduction and the Heat Equation; Author: The Efficient Engineer;https://www.youtube.com/watch?v=6jQsLAqrZGQ;License: Standard youtube license