Heat and Mass Transfer In regenerator type heat exchanger, heat transfer takes place by Direct mixing of hot and cold fluids Flow of hot and cold fluids alternately over a surface A complete separation between hot and cold fluids Generation of heat again and again Direct mixing of hot and cold fluids Flow of hot and cold fluids alternately over a surface A complete separation between hot and cold fluids Generation of heat again and again ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Kirchhoff's law states that The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body The total radiation from a black body per second per unit area is directly proportional to the fourth power of the absolute temperature None of these The wave length corresponding to the maximum energy is proportional to the absolute temperature The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body The total radiation from a black body per second per unit area is directly proportional to the fourth power of the absolute temperature None of these The wave length corresponding to the maximum energy is proportional to the absolute temperature ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The thermal diffusivities for gases are generally Dependent on the viscosity More than those for liquids Less than those for liquids More than those for solids Dependent on the viscosity More than those for liquids Less than those for liquids More than those for solids ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer In counter flow heat exchangers Both the fluids at exit are in their hottest state One fluid is in hottest state and other in coldest state at inlet Both the fluids at inlet are in their hottest state Both the fluids at inlet (of heat exchanger where hot fluid enters) are in their coldest state Both the fluids at exit are in their hottest state One fluid is in hottest state and other in coldest state at inlet Both the fluids at inlet are in their hottest state Both the fluids at inlet (of heat exchanger where hot fluid enters) are in their coldest state ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Thermal diffusivity of a substance is Directly proportional to the thermal conductivity Inversely proportional to specific heat All of these Inversely proportional to density of substance Directly proportional to the thermal conductivity Inversely proportional to specific heat All of these Inversely proportional to density of substance ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The heat transfer by conduction through a thick sphere is given by Q = 2πkr1 r2 (T1 - T2)/ (r2 - r1) Q = 8πkr1 r2 (T1 - T2)/ (r2 - r1) Q = 4πkr1 r2 (T1 - T2)/ (r2 - r1) Q = 6πkr1 r2 (T1 - T2)/ (r2 - r1) Q = 2πkr1 r2 (T1 - T2)/ (r2 - r1) Q = 8πkr1 r2 (T1 - T2)/ (r2 - r1) Q = 4πkr1 r2 (T1 - T2)/ (r2 - r1) Q = 6πkr1 r2 (T1 - T2)/ (r2 - r1) ANSWER DOWNLOAD EXAMIANS APP
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