Q. Which of the following has the minimum absorptivity ?

View solution

Q. A black body when hot, emits heat radiation of __________ wavelengths.

View solution

Q. A composite wall consists of two plates A and B placed in series normal to the flow of heat. The thermal conductivities are kA and kB and the specific heat capacities are CPA and CPB for plates A and B respectively. Plate B has twice the thickness of plate A. At steady state, the temperature difference across plate A is greater than that across plate B, when

View solution

Q. Vibrations in the tubes of a shell and tube heat exchanger is induced due to the

View solution

Q. Heat transfer by conduction in the turbulent core of a fluid flowing through a heated pipe is negligible, if the value of Prandtl number is

View solution

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

View solution

Q. 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

View solution

Q. Heat exchangers operating, when the asymptotic range is reached,

View solution

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

View solution

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

View solution

Q. Multiple effect evaporators are used to

View solution

Q. Small scale evaporation is done in a

View solution

Q. Heat exchanger tubes are never made of

View solution

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

View solution

Q. A __________ evaporator employs an annular downtake.

View solution

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

View solution

Q. In natural convection heat transfer, the correlating parameter is the

View solution

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

View solution

Q. Pick out the wrong statement.

View solution

Q. The value of Stefan-Boltazman constant in SI unit is

View solution