Q1. Which Of The Following Is NOT A Real Dimensionless Number?

A) Pectit Number
B) Stanton Number
C) Graetz Number
D) Grashof Number

Answer – A) Pectit Number

• A Number Representing A Property Of A Physical System, But Not Measured On A Scale Of Physical Units, Drag Coefficients And Stress, For Example, Are Measured As Dimensionless Numbers. Pectit Number Is NOT A Real Dimensionless Number.

READ MORE – FOOD TECHNOLOGY (01/02/2021)

Q2. Ф_v Is Generally Taken As 1 In Food Processing As Generally Very High Wall Temperatures Aren’t Reached And Hence (Μ/Μ_w) * 0.14 Is 1 As There Isn’t Much Difference In Μ And Μ_w?

A) True
B) False

Answer – A) True

• Ф_v Is Generally Taken As 1 In Food Processing As Generally Very High Wall Temperatures Aren’t Reached And Hence (Μ/Μ_w) * 0.14 Is 1 As There Isn’t Much Difference In Μ And Μ_w.

Q3. Dittus-Boelter Equation Is Applicable For Fluids With Phase Change?

A) True
B) False

Answer – A) True

• Dittus-Boelter Equation Is Applicable For Fluids Without Phase Change. Dittus-Boelter Correlation (Eq. 1.74) Is The First Heat Transfer Correlation For Turbulent Flow Inside Smooth Pipes, And This Correlation Is Used In Pipes With L D ≥ 60 And Fluid With 0.7–100 Pr Values And Re > 10,000 [5]: (1.74) Where N = 0.4 If The Fluid Is Heated In The Pipe Or N = 0.3 If The Fluid Is Cooled.

READ MORE – FOOD TECHNOLOGY (11/02/2021)

Q4. A Food Industry Keeps Food Cool In A Very Crude Manner, By Radiation. It Paints Its Walls White And Not Black, Because Of _____?

A) Kirchhoff’s Law
B) Stephan-Boltzmann Law
C) None Of The Mentioned
D) Both A And B

Answer – A) Kirchhoff’s Law

• Kirchhoff’s Law States That At Temperature Equilibrium, The Absorptivity Of A Grey Body Is Equal To Its Emissivity. Since White Paint Has Less Emissivity Than That Of Black Paint, The Wall Is Painted White.

Q5. Which Of The Following Reason Does NOT Affect Radiation Between Two Parallel Bodies?

A) Angle Of Vision
B) Orientation Of Surfaces
C) Emissivity Of Both
D) Smoothness And Roughness

Answer – A) Angle Of Vision

• The Angle Of Vision Does Not Affect Radiation Between Two Parallel Bodies. But, It Is An Important Factor When It Comes To Curved Surfaces.

READ MORE – FOOD TECHNOLOGY (30/03/2021)

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