Download GTU (Gujarat Technological University Ahmedabad) B.Tech/BE (Bachelor of Technology/ Bachelor of Engineering) 2020 Winter 5th Sem 3151404 Food Engineering Operation 1 Previous Question Paper
Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE- SEMESTER?V (NEW) EXAMINATION ? WINTER 2020
Subject Code:3151404 Date:27/01/2021
Subject Name:Food Engineering Operation-1
Time:10:30 AM TO 12:30 PM Total Marks: 56
Instructions:
1. Attempt any FOUR questions out of EIGHT questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1
(a) Write the equations of following non dimensional numbers
03
1. Nusselt Number
2. Grashof Number
3. Prandtl Number
(b) Discuss thermal conductivity of food materials. Also discuss Parallel Model, Series 04
(Perpendicular) Model and Krischer Model for prediction of thermal conductivity.
(c) Write short notes on:
07
a. Pneumatic conveyor
b. Bucket elevators
c. Screw conveyors
Q.2
(a) Differentiate between shallow and deep bin.
03
(b) Write the construction and working of rotary air screen cleaners
04
(c) What are laws of size reduction and energy calculation? In a wheat milling experiment, it 07
was found that to grind 4 mm sized grains to IS sieve 35 (0.351 mm opening), the power
requirement was 10 Kw. Calculate the power requirement for milling wheat by the same
mill to IS sieve 15(0.157 mm opening) using Rittingers' law. Feed rate of milling is 180
kg/h.
Q.3 (a) Describe the importance of shape of food products in food processing. Differentiate 03
between sphericity and roundness.
(b) What do you understand by optical and electrical properties of food materials? Give some 04
of its application in food processing.
(c) A cold store has a wall comprising of 11cm of bricks on the outside then 7.5cm of concrete 07
and then 10cm of cork. The temperature within the store is maintained -180C and outside
temperature of the wall is at 180C. Calculate the rate of heat transfer. The thermal
conductivities are for bricks, concrete and cork 0.69, 0.76 and 0.043 J/ms0C. Also
determine the temperature at interfaces between concrete and cork layers and bricks and
concrete layers.
Q.4 (a) Mention types of idlers used in belt conveyor with diagram.
03
(b) Define rheological properties of food materials. Discuss angle of repose with diagram.
04
(c) Give one design parameters for each of the following factors for designing of air screen
07
cleaners:
a. Feeding Mechnism
b. Size of screen surface
c. Grain bed depth
d. Shape of the screen opening
e. Percentage open (perforated) area
f. Angle of inclination
g. Vibrational amplitude and frequency
Q.5 (a) Write two modern storage structures used for grain storage. Mention three important 03
features of one of them.
(b) Discuss briefly the sources of infestation in grain storage.
04
(c) Explain the method of volume measurement with diagram by
07
1. Gas Displacement method
2. A platform scale method
Q.6 (a) What do you understand by Newton's Law of cooling for convection? Explain specific 03
heat and thermal diffusivity
(b) Differentiate between
04
1. Particle Density and Bulk Density
2. Open pore Porosity and Bulk Porosity
(c) Explain absorbivity, reflectivity, transmissivity and emissivity. What is Kirchhoff's law 07
and Stefan- Boltzmann law?
Q.7 (a) Define the followings
03
1. Closed pore porosity
2. Diffusion in mass transfer
3. Total Porosity
(b) Describe the important features of Pusa bin
04
(c) Describe the working of Specific Gravity Separator with diagram.
07
Q.8 (a) Define (a) screen analysis (b) Mesh (c) Ideal screen
03
(b) Discuss the concept of controlled and modified atmosphere storage in agricultural 04
produce.
(c) What do you understand by Newton's Law of cooling for convection? Explain specific
07
heat and thermal diffusivity
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This post was last modified on 04 March 2021