Heat sensitive materials can be concentrated in an evaporator employing

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.

Pick out the correct statement.

Critical value of the __________ number governs the transition from laminar to turbulent flow in free convection heat transfer.

Kirchoff's law is applicable to

The Stefan-Boltzman constant depends on the

The units of resistance to heat transfer is

A hollow sphere and a solid sphere of the same material and equal radii are heated to the same temperature. In this case,

Corrosiveness of steam condensate is due to the presence of

In a boiling curve, the peak heat flux is called the __________ point.

Three material A, B and C of equal thick-nes and of thermal conductivity of&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.

Conduction occurs in the buffer zone for a fluid flowing through a heated pipe, only when Prandtl number is

A multiple effect evaporator as compared to a single effect evaporator of the same capacity has

Thermal diffusivity of a material

A wall has two layers of materials A and B; each made of a different material. Both the layers have the same thickness. The thermal conductivity of materialA is twice that of B. Under the equilibrium, the temperature difference across the wall is 36°C. The temperature difference across the layer A is __________ °C.

At steady state the temperature variation in a plane wall, made of two different solids I & II is shown below :

The thermal conductivity of material I

In sub-cooled boiling,

A concentric double pipe heat exchanger as compared to the shell and tube heat exchanger for the same heat load requires

Open pan evaporators are preferred to be used, when the solution to be concentrated is

Three material A, B and C of equal thick-nes and of thermal conductivity of&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.

The thermal boundary layer at N_Pr > 1

In a forward feed multiple effect evaporator, the pressure is

Thermal conductivity of a gas at low density, __________ with increase in temperature.

Condensing film co-efficient for steam on horizontal tubes ranges fromtoKcal/hr.m² .°C. Condensation of vapor is carried out inside the tube in a shell and tube heat exchanger, when the

The equation, (N_St x N^2/3_Pr) = f/is the __________ analogy.

Pick out the wrong statement.

The film co-efficient between condensing vapour and metal wall increases with

With increase in temperature, the thermal conductivity of a gas

In a shell and tube heat exchanger, floating head is used for

In the free convection regime of pool boiling, the heat flux is proportional to

In a co-current double pipe heat exchanger used for condensing saturated steam over the inner tube, if the entrance and exit conditions of the coolant are interchanged, then the rate of condensation will

Nusselt number is a function of Prandtl number and __________ number of fluid in natural convection heat transfer.

The driving potential for the crystal growth during crystallisation is the __________ of the solution.

Steam trap is used to

The maximum heat transfer co-efficient from steam heating will be attained when the steam is

With increase in temperature, the thermal conductivity of fresh lubricating oil

Pick out the wrong statement.

Which of the following situations can be approximated to a steady state heat transfer system ?

is called the __________ number

jH factor for heat transfer depends upon the __________ number.

Fresh orange juice contains(by weight) solids and the rest waterof the fresh juice is sent to an evaporator to remove water and subsequently mixed with the remainingof fresh juice. The resultant product containssolids. The kg of water removed from 1 kg fresh juice is

Sensible heat absorbed by 1 lb of water when it is heated fromto 212°F may be around __________ BTU.

The maximum heat transfer co-efficient from steam heating will be attained when the steam is

kg of wet solids are to be dried fromtomoisture (by weight). The mass of moisture removed in kg is

kg of solids (on dry basis) is subjected to a drying process for a period ofseconds. The drying occurs in the constant rate period with the drying rate as, N_c = 0.5 x 10^-3 kg/m².s. The initial moisture content of the solid is 0.2 kg moisture/kg dry solid. The interfacial area available for drying is 4 m²/kg of dry solid. The moisture content at the end of the drying period is (in kg moisture/kg dry solid)

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