Q. According to Nusselt’s film theory, the film thickness decreases as we move from bottom to top. The heat transfer increases.

View solution

Q. Statement 1: Unsteady state heat transfer equation can be used when there is negligible internal resistance.
Statement 2: Unsteady state heat transfer equation can be used for liquid food items which are well stirred, because, temperature gradient within won’t be there.

View solution

Q. Statement 1: In nusselt’s film theory, velocity of the falling film is not affected by the velocity of the vapors.
Statement 2: LMTD can be used provided the overall heat transfer co-efficient is constant over a large range of temperatures.

View solution

Q. Find heat transfer in an agitated jacketed vessel if Nᵣₑᵢ is 1.5 * 105 and Nₚᵣ is 20.

View solution

Q. Which of the following is NOT a real dimensionless number?

View solution

Q. Statement 1: Nₚᵣ= (Cₚm)/kl
Statement 2: Stanton number is a product of Nᵣₑ and Nₚᵣ.

View solution

Q. Statement 1: G is known as the mass flux and it is the product of density and velocity.
Statement 2: Grashof number is associated with forced convection.

View solution

Q. Фᵥ is generally taken as 1 in food processing as generally very high wall temperatures aren’t reached and hence (µ/µw) * 0.14 is 1 as there isn’t much difference in µ and µw.

View solution

Q. Statement 1: Sieder-Tate and Dittus-boelter equations imply only to laminar flow conditions.
Statement 2: Under laminar conditions, the same equation applies both to Newtonian and Non-Newtonian fluids.

View solution

Q. Dittus-boelter equation is applicable for fluids with phase change.

View solution

Q. Statement 1: Radiation is the transfer of heat by electromagnetic waves.
Statement 2: When heat is radiated from a hot source, the amount of heat received by the body depends on the nature of the body.

View solution

Q. Statement 1: Radiation needs a medium to travel.
Statement 2: Thermal radiation takes place at a certain temperature for every body.

View solution

Q. Statement 1: Radiation is NOT heat.
Statement 2: Maximum value of absorptivity is 1.

View solution

Q. The emission of radiation by any body is independent of the radiation by any body next to it.

View solution

Q. A food industry keeps food cool in a very crude manner, by radiation. It paints its walls white and not black, because of _____

View solution

Q. Which of the following reason does NOT affect radiation between two parallel bodies?

View solution

Q. Freezer is at -18 °C. Will will be Radiative heat transfer if meat is at 298k, its emissivity is 0.82 and average area is 0.045m².
Either use Stefan Boltzmann law or take hᵣ (radiative heat transfer co-efficient) as 0.227.

ε = ( Tₐᵥ/100 )³

View solution

Q. Statement 1: Radiation dryers are used to dry grains and reduce their moisture content before storage.
Statement 2: Baking ovens are used both for making the dough and after that’s made, making biscuits by cutting them and baking them further. This entire process uses radiation.

View solution

Q. In deep freezers, the walls absorb heat from food materials by _____ and keep them cool.

View solution

Q. Radiation dryers use _____

View solution