Chemical Heat Transfer

Stefan’s block body radiation law can also be derived from ______________ law?

Byadmin March 2, 2019August 24, 2021

Stefan’s block body radiation law can also be derived from ______________ law?

A. Kirchoff’s
B. Planck’s
C. Fourier’s
D. None of these

Chemical Heat Transfer

The thermal radiative flux from a surface of emissivity = 0.4 is 22.68 kW/m2. The approximate surface temperature (K) is (Stefan-Boltzmann constant = 5.67 × 10-8 W/m2.K4) ?

The thermal radiative flux from a surface of emissivity = 0.4 is 22.68 kW/m2. The approximate surface temperature (K) is (Stefan-Boltzmann constant = 5.67 × 10-8 W/m2.K4) ?

A. 1000
B. 727
C. 800
D. 1200

Read More The thermal radiative flux from a surface of emissivity = 0.4 is 22.68 kW/m2. The approximate surface temperature (K) is (Stefan-Boltzmann constant = 5.67 × 10-8 W/m2.K4) ?
Chemical Heat Transfer

A metal ball of radius 0.1 m at a uniform temperature of 90°C is left in air at 30°C. The density and the specific heat of the metal are 3000 kg/m3 and 0.4 kJ/kg.K respectively. The heat transfer co-efficient is 50 W/m2.K Neglecting the temperature gradients inside the ball, the time taken (in hours) for the ball to cool to 60°C is_________________?

A metal ball of radius 0.1 m at a uniform temperature of 90°C is left in air at 30°C. The density and the specific heat of the metal are 3000 kg/m3 and 0.4 kJ/kg.K respectively. The heat transfer co-efficient is 50 W/m2.K Neglecting the temperature gradients inside the ball, the time taken (in hours) for the ball to cool to 60°C is_________________?

A. 555
B. 55.5
C. 0.55
D. 0.15

Read More A metal ball of radius 0.1 m at a uniform temperature of 90°C is left in air at 30°C. The density and the specific heat of the metal are 3000 kg/m3 and 0.4 kJ/kg.K respectively. The heat transfer co-efficient is 50 W/m2.K Neglecting the temperature gradients inside the ball, the time taken (in hours) for the ball to cool to 60°C is_________________?
Chemical Heat Transfer

A black body when hot, emits heat radiation of _____________ wavelengths?

A black body when hot, emits heat radiation of _____________ wavelengths?

A. Small
B. Large
C. All
D. One fixed

Read More A black body when hot, emits heat radiation of _____________ wavelengths?
Chemical Heat Transfer

Multiple effect evaporators ar used to___________________?

Multiple effect evaporators ar used to___________________?

A. Increase the steam economy & decrease the capacity
B. Increase the steam economy & the capacity
C. Decrease the steam economy & the capacity
D. Decrease the steam economy & increase the capacity

Read More Multiple effect evaporators ar used to___________________?
Chemical Heat Transfer

Baffles in the shell side of a shell and tube heat exchanger ?

Baffles in the shell side of a shell and tube heat exchanger ?

A. Increase the cross-section of the shell side liquid
B. Force the liquid to flow parallel to the bank
C. Increase the shell side heat transfer co-efficient
D. Decrease the shell side heat transfer co-efficient

Read More Baffles in the shell side of a shell and tube heat exchanger ?
Chemical Heat Transfer

Heat transfer co-efficient equation for forced convection, Nu = 0.023 Re 0.8. Pr n, is not valid, if the value of __________________?

Heat transfer co-efficient equation for forced convection, Nu = 0.023 Re 0.8. Pr n, is not valid, if the value of __________________?

A. n = 0.4 is used for heating
B. n = 0.3 is used for cooling
C. Reynolds number for the flow involved is > 10000
D. Reynolds number for the flow involved is < 2100

Read More Heat transfer co-efficient equation for forced convection, Nu = 0.023 Re 0.8. Pr n, is not valid, if the value of __________________?

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