| Tài liệu tham khảo |
Loại |
Chi tiết |
| 1. American Society of Heating, Refrigeration, and Air Conditioning Engineers, Handbook of Fundamentals, Atlanta, ASHRAE, 1993 |
Sách, tạp chí |
| Tiêu đề: |
Handbook of Fundamentals |
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| 15–10 The speed of light in vacuum is given to be 3.0 10 8 m/s. Determine the speed of light in air (n 1), in water (n 1.33), and in glass (n 1.5) |
Sách, tạp chí |
| Tiêu đề: |
n"1), in water ("n"1.33), and in glass ("n |
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| 15–13 A radio station is broadcasting radio waves at a wave- length of 200 m. Determine the frequency of these waves.Answer: 1.5 10 6 Hz |
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| 15–20 Consider a 20-cm 20-cm 20-cm cubical body at 750 K suspended in the air. Assuming the body closely approximates a blackbody, determine (a) the rate at which the cube emits radiation energy, in W and (b) the spectral black- body emissive power at a wavelength of 4 m |
Sách, tạp chí |
| Tiêu đề: |
a") the rate at which thecube emits radiation energy, in W and ("b |
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| 15–22 The sun can be treated as a blackbody at 5780 K. Using EES (or other) software, calcu- late and plot the spectral blackbody emissive power E bl of the sun versus wavelength in the range of 0.01 m to 1000 m.Discuss the results |
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| 15–27 A 3-mm-thick glass window transmits 90 percent of the radiation between l 0.3 and 3.0 m and is essentially opaque for radiation at other wavelengths. Determine the rate of radiation transmitted through a 2-m 2-m glass window from blackbody sources at (a) 5800 K and (b) 1000 K.Answers: (a) 218,400 kW, (b) 55.8 kWRadiation Properties |
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| Tiêu đề: |
a") 5800 K and ("b") 1000 K."Answers:(a") 218,400 kW, ("b |
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| 15–33 The spectral emissivity function of an opaque sur- face at 1000 K is approximated ase 1 0.4, 0 l 2 m e l e 2 0.7, 2 m l 6 me 3 0.3, 6 m lDetermine the average emissivity of the surface and the rate of radiation emission from the surface, in W/m 2 .Answers: 0.575, 32.6 kW/m 2c |
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| 15–36 The emissivity of a tungsten filament can be approxi- mated to be 0.5 for radiation at wavelengths less than 1 m and 0.15 for radiation at greater than 1 m. Determine the average emissivity of the filament at (a) 2000 K and (b) 3000 K.Also, determine the absorptivity and reflectivity of the fila- ment at both temperatures |
Sách, tạp chí |
| Tiêu đề: |
a") 2000 K and ("b |
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| 15–37 The variations of the spectral emissivity of two sur- faces are as given in Fig. P15–37. Determine the average emissivity of each surface at T 3000 K. Also, determine the average absorptivity and reflectivity of each surface for radiation coming from a source at 3000 K. Which surface is more suitable to serve as a solar absorber |
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| 15–41 The variation of the spectral transmissivity of a 0.6-cm-thick glass window is as given in Fig. P15–41. Deter- mine the average transmissivity of this window for solar radi- ation (T 5800 K) and radiation coming from surfaces at room temperature (T 300 K). Also, determine the amount of solar radiation transmitted through the window for incident solar radiation of 650 W/m 2 . Answers: 0.848, 0.00015, 551.1 W/m 2The View Factor |
Sách, tạp chí |
| Tiêu đề: |
T" 5800 K) and radiation coming from surfaces atroom temperature ("T"300 K). Also, determine the amountof solar radiation transmitted through the window for incidentsolar radiation of 650 W/m2. "Answers |
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| 15–43C How can you determine the view factor F 12 when the view factor F 21 and the surface areas are available |
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| Tiêu đề: |
F"12whenthe view factor "F |
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| 15–11 Electricity is generated and transmitted in power lines at a frequency of 60 Hz (1 Hz 1 cycle per second).Determine the wavelength of the electromagnetic waves gen- erated by the passage of electricity in power lines |
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| 15–12 A microwave oven is designed to operate at a fre- quency of 2.2 10 9 Hz. Determine the wavelength of these microwaves and the energy of each microwave |
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| 15–14 A cordless telephone is designed to operate at a fre- quency of 8.5 10 8 Hz. Determine the wavelength of these telephone waves.Blackbody Radiation |
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| 15–16C Define the total and spectral blackbody emissive powers. How are they related to each other? How do they differ |
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| 15–17C Why did we define the blackbody radiation func- tion? What does it represent? For what is it used |
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| 15–18C Consider two identical bodies, one at 1000 K and the other at 1500 K. Which body emits more radiation in the shorter-wavelength region? Which body emits more radiation at a wavelength of 20 m |
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| 15–19 Consider a surface at a uniform temperature of 800 K.Determine the maximum rate of thermal radiation that can be emitted by this surface, in W/m 2 |
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| 15–21E The sun can be treated as a blackbody at an effec- tive surface temperature of 10,400 R. Determine the rate at which infrared radiation energy (l 0.76–100 m) is emit- ted by the sun, in Btu/h ft 2 |
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| 15–23 The temperature of the filament of an incandescent lightbulb is 3200 K. Treating the filament as a blackbody, determine the fraction of the radiant energy emitted by the filament that falls in the visible range. Also, determine the wavelength at which the emission of radiation from the fila- ment peaks |
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