Heat and Mass Transfer A grey body is one whose absorptivity Varies with wavelength of the incident ray Is equal to its emissivity Varies with temperature Does not vary with temperature and. wavelength of the incident ray Varies with wavelength of the incident ray Is equal to its emissivity Varies with temperature Does not vary with temperature and. wavelength of the incident ray ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Two long parallel surfaces each of emissivity 0.7 are maintained at different temperatures and accordingly have radiation heat exchange between them. It is desired to reduce 75% of the radiant heat transfer by inserting thin parallel shields of emissivity 1 on both sides. The number of shields should be One Four Three Two One Four Three Two ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer According to Stefan's law, the total radiation from a black body per second per unit area is proportional to Absolute temperature T5 T2 T Absolute temperature T5 T2 T ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The automobile radiator is a heat exchanger of Counter flow type Cross flow type Parallel flow type Regenerator type Counter flow type Cross flow type Parallel flow type Regenerator type ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Which of the following would lead to a reduction in thermal resistance? In radiation, increasing the temperature and reducing the emissivity. All of these In convection, stirring of the fluid and cleaning the heating surface. In conduction, reduction in the thickness of the material and an increase in thermal conductivity. In radiation, increasing the temperature and reducing the emissivity. All of these In convection, stirring of the fluid and cleaning the heating surface. In conduction, reduction in the thickness of the material and an increase in thermal conductivity. ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The logarithmic mean temperature difference (tm) is given by (where Δt1 and Δt2 are temperature differences between the hot and cold fluids at entrance and exit) tm = tm = (Δt1 - Δt2) loge (Δt1/Δt2) tm = loge (Δt1/Δt2)/ (Δt1 - Δt2) tm = loge (Δt1 - Δt2)/ Δt1/Δt2 tm = (Δt1 - Δt2)/ loge (Δt1/Δt2) tm = tm = (Δt1 - Δt2) loge (Δt1/Δt2) tm = loge (Δt1/Δt2)/ (Δt1 - Δt2) tm = loge (Δt1 - Δt2)/ Δt1/Δt2 tm = (Δt1 - Δt2)/ loge (Δt1/Δt2) ANSWER DOWNLOAD EXAMIANS APP
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