All Matches

Solution Library

Expert Answer

Textbooks

Search Textbook questions, tutors and Books

Oops, something went wrong!

Change your search query and then try again

Result Not Found

Books FREE
Tutors
Study Help
Ask a Question

Search
Sign In
Register

study help
engineering
heat and mass transfer fundamentals and applications

Questions and Answers of Heat And Mass Transfer Fundamentals And Applications

Consider one-dimensional mass diffusion of species A through a plane wall. Does the species A content of the wall change during steady mass diffusion? How about during transient mass diffusion?
Write down the relations for steady one-dimensional heat conduction and mass diffusion through a plane wall, and identify the quantities in the two equations that correspond to each other.
Consider steady one-dimensional mass diffusion through a wall. Mark these statements as being True or False._____(a) Other things being equal, the higher the density of the wall, the higher the rate
A thin plastic membrane separates hydrogen from air. The molar concentrations of hydrogen in the membrane at the inner and outer surfaces are determined to be 0.045 and 0.002 kmol/m3, respectively.
Exposure to high concentration of gaseous ammonia can cause lung damage. The acceptable shortterm ammonia exposure level set by the Occupational Safety and Health Administration (OSHA) is 35 ppm for
The solubility of hydrogen gas in steel in terms of its mass fraction is given as wH2 = 2.09 × 10-4 exp(-3950/T)P0,5H2 where PH2 is the partial pressure of hydrogen in bars and T is the
Reconsider Prob. 14–54. Using EES (or other) software, plot the highest rate of hydrogen loss as a function of the mole fraction of hydrogen in natural gas as the mole fraction varies from 5 to 15
A small surface of area A1 = 3 cm2 emits radiation as a blackbody, and part of the radiation emitted by A1 strikes another small surface of area A2 = 8 cm2 oriented as shown in the figure. If the
How is the intensity of emitted radiation defined? For a diffusely emitting surface, how is the emissive power related to the intensity of emitted radiation?
A small circular plate has a diameter of 2 cm and can be approximated as a blackbody. To determine the radiation from the plate, a radiometer is placed normal to the direction of viewing from the
A radiometer can be used to determine the position of an approaching hot object by measuring the amount of irradiation it detects. Consider a radiometer placed at a distance H = 0.5 m from the x-axis
Heat dissipated from an engine in operation can cause hot spots on its surface. If the outer surface of an engine is situated in a place where oil leakage is possible, then when the leaked oil comes
Reconsider Prob. 12–58. Using the EES (or other) software, evaluate the effect of the position of the approaching object on the irradiation ratio G2,x/G2,0, where G2,x and G2,0 are the irradiation
A small circular plate with a surface A1 can be approximated as a blackbody. A radiometer with a surface A2 is placed normal to the direction of viewing from the plate at a distance L. Would the
A blackbody plate (A1 = 5 cm2) is subjected to a uniform heat flux of 1000 W/m2 on the bottom, while the top surface is exposed to an ambient surrounding at 5°C. The heat transfer coefficient due to
A long metal sheet that can be approximated as a blackbody is being conveyed through a water bath to be cooled. In order to prevent thermal burn on people handling the sheet, it must exit the water
A radiometer is employed to monitor the temperature of manufactured parts (A1 = 10 cm2) on a conveyor. The radiometer is placed at a distance of 1 m from and normal to the manufactured parts. When a
A long metal bar (cp = 450 J/kg · K, ρ = 7900 kg/m3) is being conveyed through a water bath to be quenched. The metal bar has a cross section of 30 mm × 15 mm, and it enters the water bath at
A small surface of area A1 = 5 cm2 emits radiation as a blackbody at T1 = 1000 K. A radiation sensor of area A2= 3 cm2 is placed normal to the direction of viewing from surface A1 at a distance L. An
We can see the inside of a microwave oven during operation through its glass door, which indicates that visible radiation is escaping the oven. Do you think that the harmful microwave radiation might
Consider an opaque horizontal plate that is well insulated on the edges and the lower surface. The plate is maintained at 500 K, has a total hemispherical absorptivity of 0.51 and the following
A tank is filled with chemicals undergoing an exothermic reaction. The reaction heats up the tank wall, and to prevent thermal burn on individuals, the tank’s outer surface temperature should be
A semi-transparent plate (A1 = 2 cm2) has an irradiation of 500 W/m2, where 30% of the irradiation is reflected away from the plate and 50% of the irradiation is transmitted through the plate. A
When the earth is closest to the sun, we have winter in the northern hemisphere. Explain why. Also explain why we have summer in the northern hemisphere when the earth is farthest away from the sun.
Explain why surfaces usually have quite different absorptivities for solar radiation and for radiation originating from the surrounding bodies.
You have probably noticed warning signs on the highways stating that bridges may be icy even when the roads are not. Explain how this can happen.
What changes would you notice if the sun emitted radiation at an effective temperature of 2000 K instead of 5762 K?
What is the solar constant? How is it used to determine the effective surface temperature of the sun? How would the value of the solar constant change if the distance between the earth and the sun
Explain why the sky is blue and the sunset is yellow-orange.
What is the effective sky temperature?
Solar radiation is incident on the outer surface of a spaceship at a rate of 400 Btu/h · ft2. The surface has an absorptivity of αs = 0.10 for solar radiation and an emissivity of ε = 0.6 at room
The absorber surface of a solar collector is made of aluminum coated with black chrome (αs = 0.87 and ε = 0.09). Solar radiation is incident on the surface at a rate of 600 W/m2. The air and the
The air temperature on a clear night is observed to remain at about 4°C. Yet water is reported to have frozen that night due to radiation effect. Taking the convection heat transfer coefficient to
Determine the equilibrium temperature of the absorber surface in Prob. 12–98 if the back side of the absorber is insulated.Data from problem 98The absorber surface of a solar collector is made of
A surface has an absorptivity of αs = 0.72 for solar radiation and an emissivity of ε = 0.6 at room temperature. The surface temperature is observed to be 350 K when the direct and the diffuse
Reconsider Prob. 12–98. Using EES (or other) software, plot the net rate of solar energy transferred to water as a function of the absorptivity of the absorber plate. Let the absorptivity vary from
Consider a building in New York (40° N latitude) that has 130 m2 of window area on its south wall. The windows are double-pane heat-absorbing type, and are equipped with light-colored venetian
Repeat Prob. 12–108 for a south window.Data from problem 108A typical winter day in Reno, Nevada (39° N latitude), is cold but sunny, and thus the solar heat gain through the windows can be more
Consider a building located near 40° N latitude that has equal window areas on all four sides. The building owner is considering coating the south-facing windows with reflective film to reduce the
A manufacturing facility located at 32° N latitude has a glazing area of 60 m2 facing west that consists of double-pane windows made of clear glass (SHGC = 0.766). To reduce the solar heat gain in
Repeat Prob. 11–113 for double-pane windows that are gray-tinted.Data from problem 113A house located in Boulder, Colorado (40° N latitude), has ordinary double-pane windows with 6-mm-thick
Consider a small black surface of area A = 3.5 cm2 maintained at 600 K. Determine the rate at which radiation energy is emitted by the surface through a ring-shaped opening defined by 0 ≤ ϕ ≤
A radiation sensor and a small surface of area A1 that emits radiation as a blackbody are oriented as shown in the figure. Determine the distance L at which the sensor is measuring two-thirds of the
A small surface of area A = 3 cm2 emits radiation with an intensity of radiation that can be expressed as Ie(θ, ϕ) = 100 ϕ cosθ, where Ie has the units of W/m2 · sr. Determine the emissive power
The surface in Prob. 12–122 receives solar radiation at a rate of 470 W/m2. Determine the solar absorptivity of the surface and the rate of absorption of solar radiation.Data from problem 122The
The spectral transmissivity of a 3-mm-thick regular glass can be expressed asDetermine the transmissivity of this glass for solar radiation. What is the transmissivity of this glass for light? T₁ =
A small surface of area A1 = 3 cm2 and a radiation sensor of area A2 = 1 cm2 are oriented as shown in the figure. Surface A1 is opaque (diffuse emitter and reflector) and maintains a constant
Consider a surface at 25°C in an environment at 25°C. The maximum rate of heat that can be emitted from this surface by radiation is(a) 0 W/m2(b) 155 W/m2(c) 293 W/m2(d) 354 W/m2(e) 567 W/m2
Consider a surface at 500 K. The spectral blackbody emissive power at a wavelength of 50 μm is(a) 1.54 W/m2 · μm(b) 26.3 W/m2 · μm(c) 108.4 W/m2 · μm(d) 2750 W/m2 · μm(e) 8392 W/m2 ·
The wavelength at which the blackbody emissive power reaches its maximum value at 300 K is(a) 5.1 μm(b) 9.7 μm(c) 15.5 μm(d) 38.0 μm(e) 73.1 μm
A surface absorbs 10 percent of radiation at wavelengths less than 3 mm and 50 percent of radiation at wavelengths greater than 3 μm. The average absorptivity of this surface for radiation emitted
A surface at 300°C has an emissivity of 0.7 in the wavelength range of 0–4.4 mm and 0.3 over the rest of the wavelength range. At a temperature of 300°C, 19 percent of the blackbody emissive
Consider a 4-cm-diameter and 6-cm-long cylindrical rod at 1000 K. If the emissivity of the rod surface is 0.75, the total amount of radiation emitted by all surfaces of the rod in 20 min is(a) 43
Solar radiation is incident on a semi-transparent body at a rate of 500 W/m2. If 150 W/m2 of this incident radiation is reflected back and 225 W/m2 is transmitted across the body, the absorptivity of
Solar radiation is incident on an opaque surface at a rate of 400 W/m2. The emissivity of the surface is 0.65 and the absorptivity to solar radiation is 0.85. The convection coefficient between the
A surface is exposed to solar radiation. The direct and diffuse components of solar radiation are 350 and 250 W/m2, and the direct radiation makes a 35° angle with the normal of the surface. The
Consider an enclosure consisting of 12 surfaces. How many view factors does this geometry involve? How many of these view factors can be determined by the application of the reciprocity and the
Consider a cylindrical surface and a disk oriented coaxially as shown in the figure. The cylinder has a diameter D and a length L. The disk of diameter D is placed coaxially with the cylinder at a
Repeat Prob. 13–16 with L = D.Data from problem 16Consider a cylindrical surface and a disk oriented coaxially as shown in the figure. The cylinder has a diameter D and a length L. The disk of
Determine the view factor F12 between the rectangular surfaces shown in Fig. P13–21. I'm H 1 m t I'm I'm 1 -3 m- (a) I I'm Im I'm m 1 (2) 3 m- (b) 2 m I'm I'm (1) (2 2 m- (c) 2m
A row of tubes, equally spaced at a distance that is twice the diameter of the tubes, is positioned between two large parallel plates. The surface temperature of the tubes is constant at 10°C and
This question deals with steady–state radiation heat transfer between a sphere (r1 = 30 cm) and a circular disk (r2 = 120 cm), which are separated by a center-to-center distance h = 60 cm. When the
A solid sphere of 1 m diameter at 600 K is kept in an evacuated equilateral triangular enclosure (a tetrahedron) whose side length is L. Note that for the sphere to touch the tetrahedron’s
Consider a hot cylindrical surface and a disk oriented as shown in the figure. Both the cylindrical surface and the disk behave as blackbody. The cylinder has a diameter D and a length L of 0.2 m.
Reconsider Prob. 13–53. Using EES (or other) software, investigate the effects of the rate of the heat transfer at the base surface and the temperature of the side surfaces on the temperature of
Liquid nitrogen is stored in a spherical tank of 1-m diameter, where tank surface is maintained uniformly at 80 K. The spherical tank is enclosed by a 1.6-m diameter concentric sphere with uniform
A long cylindrical black surface fuel rod of diameter 25 mm is shielded by a surface concentric to the rod. The shield has diameter of 50 mm, and its outer surface is exposed to surrounding air at
Reconsider Prob. 13–60. Using EES (or other) software, investigate the effects of the temperature and the emissivity of the hot plate on the net rate of radiation heat transfer between the plates.
This experiment is conducted to determine the emissivity of a certain material. A long cylindrical rod of diameter D1 = 0.01 m is coated with this new material and is placed in an evacuated long
Repeat Prob. 13–71 by replacing the cubic enclosure by a spherical enclosure whose diameter is 3 m.Data from problem 71A spherical tank of diameter D = 2 m that is filled with liquid nitrogen at
Liquid ammonia is being transported in an insulated tube with an outer diameter of D1 = 4 cm and the outer tube surface temperature is uniform at T1 = 0°C. Exposure to high concentration of gaseous
Reconsider Prob. 13–71. Using EES (or other) software, investigate the effects of the side length and the emissivity of the cubic enclosure, and the emissivity of the spherical tank on the net rate
A hot liquid is being transported inside a long tube with a diameter of 25 mm. The hot liquid causes the tube surface temperature to be 150°C. To prevent thermal burn hazards, the tube is enclosed
A spherical tank, with an inner diameter of D1 = 3 m, is filled with a solution undergoing an exothermic reaction that heats the surface to a uniform temperature of 120°C. To prevent thermal burn
A 3-m spherical tank storing cold fluid has a uniform surface temperature of T1 = 5°C. The lower temperature of the tank surface is causing condensation of moisture in the air at 13°C and a dew
Reconsider Prob. 13–79E. Using EES (or other) software, investigate the effect of base surface emissivity on the net rates of radiation heat transfer between the base and the side surfaces, between
What is a radiation shield? Why is it used?
A thin aluminum sheet with an emissivity of 0.15 on both sides is placed between two very large parallel plates, which are maintained at uniform temperatures T1 = 900 K and T2 = 650 K and have
What is the radiation effect? How does it influence the temperature measurements?
Give examples of radiation effects that affect human comfort.
Reconsider Prob. 13–84. Using EES (or other) software, plot the net rate of radiation heat transfer between the two plates as a function of the emissivity of the aluminum sheet as the emissivity
A radiation shield that has the same emissivity ε3 on both sides is placed between two large parallel plates, which are maintained at uniform temperatures of T1 = 650 K and T2 = 400 K and have
Reconsider Prob. 13–86. Using EES (or other) software, investigate the effect of the percent reduction in the net rate of radiation heat transfer between the plates on the emissivity of the
Two coaxial cylinders of diameters D1 = 0.10 m and D2 = 0.50 m and emissivities ε1 = 0.7 and ε2 = 0.4 are maintained at uniform temperatures of T1 = 750 K and T2 = 500 K, respectively. Now a
Reconsider Prob. 13–88. Using EES (or other) software, investigate the effects of the diameter of the outer cylinder and the emissivity of the radiation shield on the net rate of radiation heat
Two very large parallel plates are maintained at uniform temperatures of T1 = 1000 K and T2 = 800 K and have emissivities of ε1 = ε2 = 0.5, respectively. It is desired to reduce the net rate of
Two thin radiation shields with emissivities of ε3 = 0.10 and ε4 = 0.15 on both sides are placed between two very large parallel plates, which are maintained at uniform temperatures T1 = 600 K and
Five identical thin aluminum sheets with emissivities of 0.1 on both sides are placed between two very large parallel plates, which are maintained at uniform temperatures of T1 = 800 K and T2 = 450 K
Reconsider Prob. 13–91. Using EES (or other) software, investigate the effects of the number of the aluminum sheets and the emissivities of the plates on thenet rate of radiation heat transfer
Heat dissipated from an engine in operation can cause hot spots on its surface. If the outer surface of an engine is situated in a place where oil leakage is possible, then when leaked oil comes in
A thermocouple shielded by aluminum foil of emissivity 0.15 is used to measure the temperature of hot gases flowing in a duct whose walls are maintained at Tw = 380 K. The thermometer shows a
How does radiation transfer through a participating medium differ from that through a nonparticipating medium?
Define spectral transmissivity of a medium of thickness L in terms of(a) Spectral intensities(b) The spectral absorption coefficient.
How does the wavelength distribution of radiation emitted by a gas differ from that of a surface at the same temperature?
Define spectral emissivity of a medium of thickness L in terms of the spectral absorption coefficient.
Consider an equimolar mixture of CO2 and O2 gases at 800 K and a total pressure of 0.5 atm. For a path length of 1.2 m, determine the emissivity of the gas.
A cylindrical container whose height and diameter are 8 m is filled with a mixture of CO2 and N2 gases at 600 K and 1 atm. The partial pressure of CO2 in the mixture is 0.15 atm. If the walls are
Repeat Prob. 13–101 by replacing CO2 by the H2O gas.Data from problem 101A cylindrical container whose height and diameter are 8 m is filled with a mixture of CO2 and N2 gases at 600 K and 1 atm.
A 3-m-diameter spherical furnace contains a mixture of CO2 and N2 gases at 1200 K and 1 atm. The mole fraction of CO2 in the mixture is 0.15. If the furnace wall is black and its temperature is to be
A cubic furnace whose side length is 6 m contains combustion gases at 1000 K and a total pressure of 1 atm. The composition of the combustion gases is 75 percent N2, 9 percent H2O, 6 percent O2, and

Showing 800 - 900 of 2100

First
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Last

Get In Touch

About Us
Contact Us
Career
Jobs
FAQ
Campus Ambassador

Company Info

Security
Copyrights
Privacy Policy
Terms & Condition
SolutionInn Fee
Scholarship

Services

Sitemap
Fun
Definitions
Become Tutor
Study Help Categories
Recent Questions
Expert Questions

Copyright © 2024 SolutionInn All Rights Reserved.

Get the SolutionInn - Study Help App