Food Engineering Operations - I — Summer 2019

What is screening? Write the purpose of screen motion.

Describe the different types of idlers used for belt conveyor.

What is Fourier’s law of heat conduction? Derive an expression for heat conductance when the walls are in series (composite wall).

State the principles of diffusion when two fluids are miscible.

Define plane of rupture. How shallow and deep bins are differentiated on basis of plane of rupture and angle of rupture?

Enlist the traditional and improved storage structures used in India. Describe in detail cover and plinth storage structure with suitable diagram.

Discuss the stepwise design procedure to calculate the convective heat transfer coefficient. Acomposite wall of a furnace has 2 layers of equal thickness having thermal conductivities in the ratio of 3:2. What is the ratio of the temperature drop across the two layers?

Show diagrammatically the vertical and lateral pressure variation in a bin.

Define the followings 1. Open pore porosity and Closed pore porosity 2. Thermal diffusivity and Thermal conductivity

Derive an expression of conduction heat transfer when the pipes of different materials are in series.

Calculate Prandtl Number when air at 1000C   1 . 4 61 x1 0 -6  .T T 3 / Kg / m s03 C 0.917 2.58x104T3.98x108T2 kJ/kg K (where Tis the absolute temperature p in Kelvin), k = 0.03186 w/mK

Derive an expression of terminal velocity for spherical body.

Asteel pipe with 50 mm outer diameter is covered with a 6.4 mm asbestos insulation (k = 0.166 W/mK) followed by a 25 mm layer of fiber glass insulation ( k = 0.0485 W/mK). The pipe wall temperature is 393K and outside insulation temperature is 311K. Calculate the interface temperature between the asbestos and the fiber glass.

What are the different sources of infestation for stored grain?

Discuss variety of pores are available in food grains with diagram.

(i) Write Bond’s law for size reduction. (ii) In a wheat milling experiment, it 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 (1) Rittingers’ law (2) Kicks’ law. Feed rate of milling is 180 kg/h.

Write a procedure to measure angle of repose of a grain with help of a labeled diagram and formula.

Differentiate between continuous phase and dispersed phase. List out the application of diffusion in food industry.

(i) Define belt tension. (ii) The capacity of toughened belt conveyor of 70 m length is 60 m3/hr. Width of the belt is 61 cm and cross sectional area of the belt is 0.0309 m2. Calculate belt speed and horse power for given belt conveyor. Given the constant Aand Bfor the belt is 0.36 and 0.00298 respectively.

Describe the process of mass transfer in gas-liquid system with graph.

Define the followings and represents with graph 1. Shear thinning 2. Shear thickening 3. Newtonian fluid 4. Non-Newtonian fluid

List out the importance of engineering properties of food materials. Give the description of following shapes with diagram

Round, (b) Oblate, (c) Oblong, (d) Conic, (e) Ovate, (f) Truncate

Draw the flow pattern of grain while emptying through a vertical silo.

Discuss the importance of angle of repose, internal and external friction in design of modern silo.

(i) Define effectiveness of screen. (ii) Wheat is milled in burr mill. The ground product was later on analysed in as set of IS sieve. The screen analysis data is given below in table. Calculate the screen effectiveness of (i) IS 40 mesh (ii) IS 20 mesh IS screen number 100 70 50 40 30 20 15 Pan % Feed -- material 2 10 29 36 16 4 retained Overflow -- -- over each Underflow -- -- screen 5 9 51 20 7 82