Q. __________ is when nucleate boiling transforms to film boiling.

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Q. Statement 1: Nucleate Boiling is when a layer of film is formed in the beginning.
Statement 2: Boiling starts with the bottom layer which heats up, becomes light and goes up. That way everything becomes hot and there is not temperature difference and hence no heat transfer.

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Q. Statement 1: When heat transfer takes between a solid surface and a fluid, an insulating film layer is formed. More is the agitation; more is the thickness of the film.
Statement 2: Within the film, the temperature varies from the wall to the temperature of the bulk.

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Q. Statement 1: Nₚᵣ= (Cₚμ)/k
Statement 2: If Nₚᵣ is lesser than 1, Thermal Boundary layer is thinner than Hydrodynamic Boundary layer.

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Q. Why is better to use a Jacketed vessel in the dairy industry than a stainless steel container directly?

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Q. Statement 1: hd/k is _____
Statement 2: _____ is the ratio of convective heat transfer to conductive heat transfer.

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Q. The reciprocal of heat transfer co-efficient is _____

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Q. Statement 1: Film-type condensation has a higher heat transfer co-efficient than drop-wise condensation.
Statement 2: Drop-wise condensation is easier to maintain than Film-type condensation

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Q. Statement 1: Drop-wise condensation takes place on a smooth surface.
Statement 2: All the resistance to heat transfer lies in the film formed during Film-type condensation.

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

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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.

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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.

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

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

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

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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.

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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.

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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.

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

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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.

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