Chemical Heat Transfer

The absorptivity of a grey body at a given temperature _____________ with increasing wavelength of radiation?

Byadmin March 2, 2019August 24, 2021

The absorptivity of a grey body at a given temperature _____________ with increasing wavelength of radiation?

A. Increases
B. Decreases
C. Remain constant
D. May increase or decrease; depends on the material

CHEMICAL ENGINEERING | Chemical Heat Transfer

Maximum heat transfer rate can be expected in case of_________?

Maximum heat transfer rate can be expected in case of_________?A. Laminar flow
B. Co-current flow
C. Turbulent flow
D. Heat flow rate is independent of nature of flow

Read More Maximum heat transfer rate can be expected in case of_________?
Chemical Heat Transfer

At what value of Prandtl number, conduction is negligible in the turbulent core of a fluid flowing through a heated pipe ?

At what value of Prandtl number, conduction is negligible in the turbulent core of a fluid flowing through a heated pipe ?

A. 0.5
B. < 0.5
C. > 0.6
D. < 0.1

Read More At what value of Prandtl number, conduction is negligible in the turbulent core of a fluid flowing through a heated pipe ?
Chemical Heat Transfer

The inner wall of a furnace is at a temperature of 700°C. The composite wall is made of two substances, 10 and 20 cm thick with thermal conductivities of 0.05 and 0.1 W.m-1.°C- 1 respectively. The ambient air is at 30°C and the heat transfer co-efficient between the outer surface of wall and air is 20 W.m-2.°C-1. The rate of heat loss from the outer surface in W.m-2is__________________?

The inner wall of a furnace is at a temperature of 700°C. The composite wall is made of two substances, 10 and 20 cm thick with thermal conductivities of 0.05 and 0.1 W.m-1.°C- 1 respectively. The ambient air is at 30°C and the heat transfer co-efficient between the outer surface of wall and air is 20 W.m-2.°C-1. The rate of heat loss from the outer surface in W.m-2is__________________?

A. 165.4
B. 167.5
C. 172.5
D. 175

Read More The inner wall of a furnace is at a temperature of 700°C. The composite wall is made of two substances, 10 and 20 cm thick with thermal conductivities of 0.05 and 0.1 W.m-1.°C- 1 respectively. The ambient air is at 30°C and the heat transfer co-efficient between the outer surface of wall and air is 20 W.m-2.°C-1. The rate of heat loss from the outer surface in W.m-2is__________________?
Chemical Heat Transfer

Double pipe heat exchangers are used__________________?

Double pipe heat exchangers are used__________________?

A. When heat transfer area required is very high
B. When heat transfer area required is very low, i.e. (100-200 ft2).
C. Because it occupies less floor area
D. Because it is less costly

Read More Double pipe heat exchangers are used__________________?
Chemical Heat Transfer

Which of the following is generally considered as opaque surface towards radiations ?

Which of the following is generally considered as opaque surface towards radiations ?

A. Gases
B. Solids
C. Liquids
D. Both B. and C.

Read More Which of the following is generally considered as opaque surface towards radiations ?
Chemical Heat Transfer

Three materials A, B and C of equal thickness and of thermal conductivity of 20, 40 & 60 kcal/hr. m. °C respectively are joined together. The temperature outside of A and C are 30°C and 100°C respectively. The interface between B and C will be at a temperature of ____________ °C?

Three materials A, B and C of equal thickness and of thermal conductivity of 20, 40 & 60 kcal/hr. m. °C respectively are joined together. The temperature outside of A and C are 30°C and 100°C respectively. The interface between B and C will be at a temperature of ____________ °C?

A. 40
B. 95
C. 70
D. 50

Read More Three materials A, B and C of equal thickness and of thermal conductivity of 20, 40 & 60 kcal/hr. m. °C respectively are joined together. The temperature outside of A and C are 30°C and 100°C respectively. The interface between B and C will be at a temperature of ____________ °C?

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