Heat and Mass Transfer Depending on the radiating properties, a body will be white when(Where a = absorptivity, p = reflectivity, x = transmissivity) X = 0, a + p = 1 P=1, T = 0 and a = 0 P = 0, x = 0 and a = 1 P = 0, x = 1 and a = 0 X = 0, a + p = 1 P=1, T = 0 and a = 0 P = 0, x = 0 and a = 1 P = 0, x = 1 and a = 0 ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The critical thickness of insulation for a sphere is 2k/h₀ h₀/k h₀/2k k/h₀ 2k/h₀ h₀/k h₀/2k k/h₀ 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 Two Three Four One Two Three Four ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Total heat is the heat required to Increase the temperature of a liquid or vapour Change liquid into vapour Convert water into steam and superheat it Change vapour into liquid Increase the temperature of a liquid or vapour Change liquid into vapour Convert water into steam and superheat it Change vapour into liquid ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Film coefficient is defined as Inside diameter of tube Thermal conductivity Equivalent thickness of film Specific heat × Viscosity Thermal conductivity Molecular diffusivity of momentum Thermal diffusivity Film coefficient × Inside diameter Thermal conductivity Equivalent thickness of film Thermal conductivity Equivalent thickness of film Specific heat × Viscosity Thermal conductivity Molecular diffusivity of momentum Thermal diffusivity Film coefficient × Inside diameter Thermal conductivity Equivalent thickness of film ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer According of Kirchhoff's law Radiant heat is proportional to fourth power of absolute temperature Emissive power depends on temperature Emissive power and absorptivity are constant for all bodies Ratio of emissive power to absorptive power for all bodies is same and is equal to the emissive power of a perfectly black body Radiant heat is proportional to fourth power of absolute temperature Emissive power depends on temperature Emissive power and absorptivity are constant for all bodies Ratio of emissive power to absorptive power for all bodies is same and is equal to the emissive power of a perfectly black body ANSWER DOWNLOAD EXAMIANS APP
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