In a shell and tube heat exchanger, putting a longitudinal baffle across the shell, forces the shell side fluid to pass __________ through the heat exchanger.

The main function of baffles provided in a shell and tube heat exchanger is to

The ratio of kinematic viscosity to thermal diffusivity is called the __________ number.

The Fourier number (defined as a.t/L²) is used in the analysis of problem involving heat transfer by

For condensation of pure vapors, if the heat transfer co-efficients in filmwise and drop-wise condensation are respectively h_f and h_d, then

Overall thermal resistance for conductive heat transfer through a series of flat resistances is equal to the

For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally

Multiple effect evaporation is generally recommended, when the

The statement that "maximum wavelength of radiation is inversly proportional to the temperature" is __________ law.

Steam condensate is recovered by steam traps and recycled for use as boiler feed water, because of its low

When does the heat generated by fluid friction becomes appreciable compared to the heat transferred between the fluids ?

Rate of crystallisation does not depend upon the

Fluid motion in the natural convection heat transfer between a solid surface and a fluid in contact with it, results from the

The average heat transfer co-efficient over the entire length of the plate (h_a) and the local heat transfer co-efficient (h_L), in case of heat transfer over a flat plate in lminar zone is related as

At Pr >conduction in an ordinary fluid flowing through a heated pipe is limited to the

Heat flux, as defined in heat flow is analogous to __________ in electricity flow.

The wavelength at which the maximum monochromatic emissive power occurs for a black body, is (where, T = absolute temperature of the black body)

The film thickness for laminar film condensation on vertical surface __________ from top to bottom.

The equation, N_st = f/is the __________ analogy.

Boiling point elevation for a strong and concentrated solution is found by Duhring's rule, which states that at the same pressure, the boiling point of a solution is a linear function of the __________ of pure water.

What is the emissivity of a black body ?

When the ratio of the Grashoff number and to the square of Reynolds number is one, the dominant mechanism of heat transfer is

The energy radiated from a surface Q at absolute temperature T is related as

Pick out the wrong statement:

Double pipe heat exchangers are preferably useful, when

The inside heat transfer co-efficient in case of turbulent flow of liquid in the tube side in a 1-2 shell and tube heat exchanger is increased by __________ times, when the number of tube passes is increased to 8.

The Sieder-Tate correlation for heat transfer in turbulent flow in pipe gives Nu α Re^0.8, where, Nu is the Nusselt number and Re is the Reynolds number for the flow. Assuming that this relation is valid, the heat transfer co-efficient varies with the pipe diameter (D) as

If a single tube pass heat exchanger is converted to two pass, then for the same flow rate, the pressure drop per unit length in tube side will

Stefen's block body radiation law can also be derived from __________ law.

Evaporator tubes are generally

In a single evaporator system, the steam economy __________ by creating vacuum in the evaporator.

Steam is routed through the tube in case of a __________ evaporator.

The purpose of providing bleed points in the evaporator is to

Removal of __________ heat is involved in the condensation of a vapor under saturated conditions.

__________ heat exchanger is the most suitable, when the temperature of shell side fluid is much higher than that of tube side.

A long iron rod initially at a temperature of 20°C has one end dipped in boiling water (100°C) at time, t =The curved surface of the rod is insulated so that heat conduction is one dimensional in the axial direction. The temperature at a distancemm from the dipped end becomes 40°C at time, t =s. The same temperature is achieved at a distance ofmm from the dipped end at time

A steel sphere of radius 0.1 m at 400°K is immersed in an oil at 300°K. If the centre of the sphere reaches 350°K inminutes, how long will it take for a 0.m radius steel sphere to reach the same temperature (at the centre) under identical conditions ? Assume that the conductive heat transfer co-efficient is infinitely large.

The unit of conductance in SI unit is

__________ heat exchanger is used for chilling oil to be dewaxed.

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

Kg of liquid evaporated per hour in an evaporator is defined as its

Nusselt number is the ratio of the temperature gradient at the wall to

Multipass heat exchangers are used

Which of the following parameters of the fluid is not very important, while deciding its route in a shell and tube heat exchanger?

Maximum heat transfer rate is achieved in __________ flow.

Wavelength corresponding to the maximum energy is inversely proportional to the absolute temperature. This is __________ law.

Dropwise condensation of steam on cooling surface is promoted

Water always boils when its

LMTD for evaporators & condensers for a given terminal parameters & set of conditions for counterflow is equal to that for parallel flow. In such heat exchangers, with one of the fluids condensing or evaporating, the surface area required is the least in the __________ flow.

In a shell and tube heat exchanger, square pitch compared to triangular pitch