Value of Nusselt number [Nu = (hD/k)] for the heat transfer by conduction from a droplet or a spherical particle to a surrounding stagnant film is

At constant temperature, the thermal conductivities of gases __________ with rise in pressure.

Mode of heat transfer involved in the cooling of air cooled internal combustion engine is

For __________ Prandtl number values, the heat conduction will be negligible in the buffer zone.

A __________ evaporator employs an annular downtake.

In Biot number, the characteristic length used is the ratio of the __________ of the solid.

At constant temperature, the thermal conductivities of gases __________ with rise in pressure.

In a heat exchanger with steam outside the tubes, a liquid gets heated to 45°C, when its flow velocity in the tubes is 2 m/s. If the flow velocity is reduced to 1 m/s, other things remaining the same, the temperature of the exit liquid will be

The purpose of providing expansion bellows in the shell of tubular exchanger is to

Pick out the wrong statement.

Steady state one dimensional heat flow by conduction as given by Fourier's low does not assume that

The radiation heat flux from a heating element at a temperature of 800°C, in a furnace maintained at 300°C is 8 kW/m². The flux, when the element temperature is increased to 1000°C for the same furnace temperature is

Radiation heat losses from satisfactorily insulated high pressure boilar may be about __________ percent.

Which of the following is the most widely used heat insulating material for pipelines carrying steam ?

'Duhring's plot' is of use in

The left face of a one dimensional slab of thickness 0.2 m is maintained at 80°C and the right face is exposed to air at 30°C. The thermal conductivity of the slab is 1.2 W/m.K and the heat transfer co-efficient from the right face isW/m².K. At steady state, the temperature of the right face in °C is

Heat exchangers operating, when the asymptotic range is reached,

In natural convection heat transfer, the correlating parameter is the

Heat transfer co-efficient equation for forced convection, Nu = 0.R_e^0.8 . P_rⁿ, is not valid, if the value of

Reason for operating an evaporator in multiple effect is to secure

Which has the lowest Prandtl number ?

Multiple effect evaporation accounts for

In case of a supercooled solution, which is on the verge of crystallisation, the free energy of the solution as compared to that of the solid is

Grashhoff number is given by

Evaporation by thermocompression results in the

In a shell and tube heat exchanger, the shell side fluid velocity can not be changed by changing the

In case of a shell and tube heat exchanger, the minimum and maximum baffle spacing is respectively (where, D = inside diameter of the shell)

Boiling of milk in an open vessel is an example of __________ boiling.

Which is the best tube arrangement (in a shell and tube heat exchanger) if the fluids are clean and non-fouling ?

Evaporation by thermocompression results in the

In a cooling tower, water becomes cool by

Pick out the wrong statement.

Maximum water velocity in tubes of a 1-2 shell and tube heat exchanger may be around __________ metres/second.

The overall heat transfer co-efficient for a shell and tube heat exchanger for clean surfaces is U₀ =W/m².K. The fouling factor after one year of operation is found to be h_d0 =W/m².K. The overall heat transfer co-efficient at this time is

Forced circulation evaporators are normally used for concentrating liquids having

To reduce the tube side pressure drop for the same flow rate, the heat exchanger recomended is

In case of heat transfer by conduction in a hollow cylinder, __________ mean area is used to calculate the heat transfer rate.

Pick out the wrong statement.

In case of a multipass shell and tube heat exchanger, the temperature drop in the fluid

In Fourier's law, the proportionality constant is called the

Prandtl number for most of dry gases is about

In a laboratory test run, the rate of drying was found to be 0.5 x 10^-3 kg/m².s, when the moisture content reduced from 0.4 to 0.1 on dry basis. The critical moisture content of the material is 0.on a dry basis. A tray dryer is used to drykg (dry basis) of the same material under identical conditions. The surface area of the material is 0.m²/kg of dry solid. The time required (in seconds) to reduce the moisture content of the solids from 0.3 to 0.2 (dry basis) is

Steam economy in case of a triple effect evaporator will be

The heat transfer co-efficient in film type condensation is __________ that for dropwise condensation.

Prandtl number is the reciprocal of

Maximum water velocity in tubes of a 1-2 shell and tube heat exchanger may be around __________ metres/second.

Pick out the wrong statement.

In a laboratory test run, the rate of drying was found to be 0.5 x 10^-3 kg/m².s, when the moisture content reduced from 0.4 to 0.1 on dry basis. The critical moisture content of the material is 0.on a dry basis. A tray dryer is used to drykg (dry basis) of the same material under identical conditions. The surface area of the material is 0.m²/kg of dry solid. The time required (in seconds) to reduce the moisture content of the solids from 0.3 to 0.2 (dry basis) is

In a heat exchanger, the rate of heat transfer from the hot fluid to the cold fluid

Intermittant tube cleaning is possible to be done in case of a __________ evaporator.