Unit operations in Dairy and Food engineering - Dairy and Food Engineering - Agricultural Engineering Previous Year Questions

1

2008 · Agricultural Engineering · Dairy and Food Engineering · Unit operations in Dairy and Food engineering

Agricultural Engineering (AG) 2008

The viscosity of milk at 21 °C is 2.1 x 10⁻³ Pa s and its density at this temperature is 1029 kg m⁻³. Milk flows at the rate of 0.12 m³ min⁻¹ in a 2.5 cm diameter pipe. At 21 °C, the flow of milk will be

A

stream line

B

laminar

C

transition

D

turbulent

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2

2011 · Agricultural Engineering · Dairy and Food Engineering · Unit operations in Dairy and Food engineering

Agricultural Engineering (AG) 2011

Milk is agitated in a tank with a rotating impeller. For this system: Let \(X = \frac{P}{\rho N^3 D^5}\), \(Y = \frac{D^2 N \rho}{\mu}\), \(Z = \frac{D N^2}{g}\) where, P = power imparted by the impeller to the fluid, N = rate of rotation of the impeller, D = impeller diameter, g = acceleration due to gravity, \(\rho\) = fluid density, and \(\mu\) = fluid viscosity. The X , Y , Z are

A

X = Grashof number, Y = Power number, Z = Reynolds number

B

X = Power number, Y = Reynolds number, Z = Froude number

C

X = Reynolds number, Y = Froude number, Z = Grashof number

D

X = Froude number, Y = Grashof number, Z = Power number

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3

2013 · Agricultural Engineering · Dairy and Food Engineering · Unit operations in Dairy and Food engineering

Agricultural Engineering (AG) 2013

A milk fat globule of 2 μm diameter is rising in whole milk of density 1030 kg m^-3 and coefficient of viscosity 10^-3 Poise. If the fat density is 950 kg m^-3, the time needed to rise 10 mm for this fat globule in min is

A

0.57

B

34.57

C

35.57

D

95.57

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4

2014 · Agricultural Engineering · Dairy and Food Engineering · Unit operations in Dairy and Food engineering

Agricultural Engineering (AG) 2014

A centrifuge with rotational speed of 1440 rpm is used for separation. The oil from a dispersion in water is present in the form of spherical globules of 4.7 μm diameter. The density of oil is 850 kg m−3. Separation occurs at an effective radius of 4 cm. Viscosity and density of water are 0.705 cP and 1000 kg m−3, respectively. The velocity of oil through water, in mm s−1, is ____.

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5

2016 · Agricultural Engineering · Dairy and Food Engineering · Unit operations in Dairy and Food engineering

Agricultural Engineering (AG) 2016

A high speed tubular ultracentrifuge with bowl radius of 100 mm and height 500 mm rotates at 20000 rpm and settles starch particles (average diameter of 20µm) on the wall. The ratio of centrifugal force to the gravitational force acting on the particle is ______

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6

2018 · Agricultural Engineering · Dairy and Food Engineering · Unit operations in Dairy and Food engineering

Agricultural Engineering (AG) 2018

A single strength fruit juice is concentrated from 6% total solids (TS) to 24% by ultrafiltration. The feed stream has a flow rate of 12 kg min⁻¹. The ultrafiltration membrane tube has an inside diameter of 80 mm and the pressure difference applied across the membrane is 2 MPa. If the permeability constant is 4×10⁻⁵ kg water m⁻² kPa⁻¹ s⁻¹, the length of the membrane tube is ______ m.

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7

2019 · Agricultural Engineering · Dairy and Food Engineering · Unit operations in Dairy and Food engineering

Agricultural Engineering (AG) 2019

A cream separator has discharge radii of 6 cm and 9 cm and the density of cream and skim milk are 860 and 1035 kg m^-3, respectively. The ideal radius (in meter) for placing the feed inlet is

A

0.085

B

0.098

C

0.113

D

0.174

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8

2020 · Agricultural Engineering · Dairy and Food Engineering · Unit operations in Dairy and Food engineering

Agricultural Engineering (AG) 2020

Saturated steam at 121 °C is used to sterilize pineapple juice by direct steam injection. The initial temperature of the juice is 80 °C and after sterilization, the blend of diluted juice exits the sterilizer at 95 °C. The enthalpy values of steam and condensate water are given in Table below. Specific heat capacity of the juice is 3.9 kJ kg⁻¹ °C⁻¹. Assuming no energy loss to the surroundings in the process of sterilization, the ratio of juice sterilized to steam utilized is

A

34.79

B

37.94

C

39.47

D

43.97

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9

2021 · Agricultural Engineering · Dairy and Food Engineering · Unit operations in Dairy and Food engineering

Agricultural Engineering (AG) 2021

Rushton turbine having an impeller diameter of 20 cm and operating at a stirrer speed of 200 rpm is used in a mixing tank. If the tank receives air at a volumetric flow rate of 0.2 m³ min^-1, the non-dimensional Froude Number, \(N_{Fr}\) is ______. [round off to 2 decimal places]

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10

2022 · Agricultural Engineering · Dairy and Food Engineering · Unit operations in Dairy and Food engineering

Agricultural Engineering (AG) 2022

A falling ball viscometer is used to determine the dynamic viscosity of sunflower oil. The viscometer has a tube length of 10 cm with the ball diameter of 0.68 mm. The densities of oil and the ball are 921 kg m⁻³ and 2420 kg m⁻³, respectively. If the ball takes 44.5 s to fall from top of the tube, the viscosity of the oil in Pa s is _______. [round off to three decimal places]
(Take g = 9.81 m s⁻²)

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11

2023 · Agricultural Engineering · Dairy and Food Engineering · Unit operations in Dairy and Food engineering

Agricultural Engineering (AG) 2023

If the diameter of fat globule in a cream separator is reduced to half and the rotational speed of the centrifuge increased to three times, the terminal settling velocity of fat globule is

A

decreased to 0.44 times

B

increased to 0.44 times

C

decreased to 2.25 times

D

increased to 2.25 times

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12

2023 · Agricultural Engineering · Dairy and Food Engineering · Unit operations in Dairy and Food engineering

Agricultural Engineering (AG) 2023

The lighter liquid layer and the interphase layer in a basket centrifuge, rotating at a speed of 1000 rpm, are 0.1025 m and 0.105 m away from the center, respectively. Considering the densities of lighter and heavier liquids as 920 kg m⁻³ and 1015 kg m⁻³, respectively, the differential pressure in horizontal direction required to maintain the interphase layer in kPa is __________ (rounded off to 3 decimal places, Consider π = 3.14).

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13

2023 · Agricultural Engineering · Dairy and Food Engineering · Unit operations in Dairy and Food engineering

Agricultural Engineering (AG) 2023

The upstream and downstream pressures in a homogenizer during homogenization of milk are maintained at 250 bar and 10 bar, respectively. If density of milk is 1030 kg m⁻³, then the velocity at which milk comes out of the homogenizing valve in m s⁻¹ is __________ (rounded off to 3 decimal places).

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