Open pan evaporators are preferred to be used, when the solution to be concentrated is_________________?
A. Scaling
B. Highly viscous
C. Corrosive
D. Salty
Month: March 2019
When warm and cold liquids are mixed, the heat transfer is mainly by_______________?
When warm and cold liquids are mixed, the heat transfer is mainly by_______________?
A. Conduction
B. Convection
C. Radiation
D. Both A. & C.
At constant temperature, the thermal conductivities of gases _____________ with rise in pressure?
At constant temperature, the thermal conductivities of gases _____________ with rise in pressure?
A. Decrease
B. Increase
C. Remain unchanged
D. May increase or decrease; depends on the pressure
A single pass air heater is connected to a two pass unit. For the air flow rate and other conditions remaining the same, the film heat transfer co-efficient for air will vary in the ratio of__________________?
A single pass air heater is connected to a two pass unit. For the air flow rate and other conditions remaining the same, the film heat transfer co-efficient for air will vary in the ratio of__________________?
A. 2
B. 20.8
C. 20.2
D. 20.5
It is not preferable to use superheated steam in evaporators, because of its very_________________?
It is not preferable to use superheated steam in evaporators, because of its very_________________?
A. High temperature
B. High pressure
C. Low film co-efficient
D. None of these
_____________ heat exchanger is used for chilling oil to be dewaxed?
_____________ heat exchanger is used for chilling oil to be dewaxed?
A. U-tube
B. Double pipe
C. Fixed tube
D. Floating head
If heat transfer rate varies with the time, it is termed as__________________?
If heat transfer rate varies with the time, it is termed as__________________?
A. Forced convection
B. Steady state conduction
C. Monochromatic radiation
D. None of these
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
The absorptivity of a body is equal to its emissivity _________________?
The absorptivity of a body is equal to its emissivity _________________?
A. At a particular temperature
B. For circular bodies
C. Under thermal equilibrium
D. None of these
A perfect black body is a perfect _____________ of radiation?
A perfect black body is a perfect _____________ of radiation?
A. Absorber
B. Emitter
C. Both A. & B.
D. Neither A. nor B.