Q. The main purpose of providing fins on heat transfer surface is to increase the

View solution

Q. A BTU/hr.ft.² °F is equal to

View solution

Q. Which of the following has the lowest Prandtl number ?

View solution

Q. Choose the most important factor on which the heat conducted through a wall in a unit time will depend on ?

View solution

Q. Which of the following has the minimum thermal conductivity ?

View solution

Q. In a heat exchanger, one transfer unit means

View solution

Q. For condensation of pure vapors, if the heat transfer co-efficients in filmwise and drop-wise condensation are respectively hf and hd, then

View solution

Q. Pick out the wrong statement:

View solution

Q. The advantage of backward feed multiple effect evaporators over forward feed units is that

View solution

Q. Which of the following is the most controlling factor for the rate of bubble detachment from the hot solid surface ?

View solution

Q. Which characteristic of a fluid is not important in deciding its route in a shell and tube heat exchanger ?

View solution

Q. Thermal conductivities of most of the liquids __________ with rise in temperature.

View solution

Q. A metal ball of radius 0.1 m at a uniform temperature of 90°C is left in air at 30°C. The density and the specific heat of the metal are 3000 kg/m³ and 0.4 kJ/kg.K respectively. The heat transfer co-efficient is 50 W/m².K Neglecting the temperature gradients inside the ball, the time taken (in hours) for the ball to cool to 60°C is

View solution

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

View solution

Q. Arithmetic mean area can be used in heat transfer problem to calculate the heat flow by conduction through a cylinder which is

View solution

Q. Three solid objects of the same material and of equal mass-a sphere, a cylinder (length = diameter) and a cube are at 500°C initially. These are dropped in a quenching bath containing a large volume of cooling oil each attaining the bath temperature eventually. The time required for 90% change in temperature is the smallest for

View solution

Q. Overall heat transfer co-efficient for cooling of hydrocarbons by water is about

View solution

Q. For concentrating an aqueous solution of a material like anhydrous Na₂SO₄, whose solubility decreases with rise in temperature, the most suitable evaporator is a __________ evaporator.

View solution

Q. Circulation pump is located below the evaporater to

View solution

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

View solution