The main reason why air-conditioner indoor machines can have multiple colors is
A. The difference in emissivity of different colors paints at room temperature is small
B. The emissivity of different colors paints varies greatly at room temperature
C. The absorptance of different colors paints to visible light is quite different at room temperature
D. The difference in the absorptance of different colors paint to visible light at room temperature is small
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The heat dissipation method of exterior surface of indoor radiator in the northern area in winter is
A. Natural convection heat transfer
B. Radiative heat transfer
C. Mixed convection heat transfer (natural convection heat transfer and forced convection heat transfer)
D. Compound heat transfer (natural convection heat transfer and radiation heat transfer)
The reason why the extraction thermocouple with heat shelter can improve the accuracy of temperature measurement is that
A. The extraction thermocouple with heat shelter greatly reduces the radiative heat transfer on the surface of the thermocouple
B. The extraction thermocouple with heat shelter greatly increases the radiation heat transfer on the surface of the thermocouple
C. The extraction thermocouple with heat shelter increases the convective heat transfer coefficient of the thermocouple surface
D. The extraction thermocouple with heat shelter greatly reduces the convection heat transfer on the surface of the thermocouple
Which of the following descriptions about the characteristics of gas radiation is wrong
A. Radiation and absorption of different types of gases may be quite different
B. Radiation and absorption of gas may have obvious selectivity for wavelength
C. The conclusion of Kirchhoff's law is also applicable to most gas radiation
D. Radiation and absorption of gas takes place in the entire volume
Two infinite parallel plates with emissivity of 0.3 and 0.5 respectively, the temperature is maintained at 800℃ and 370℃, a heat shelter with an emissivity ε of 0.05 on both sides of the surface is added in the middle. When the radiation reaches equilibrium, the temperature of the heat shield is
A. 551 ℃
B. 651 ℃
C. 751 ℃
D. 851 ℃
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