ICAR AIEEA-PG: Dairy Science (group 16) and Dairy Technology (group 17) · India · NTA for ICAR
Original practice questions written to the published syllabus · not past papersFluid properties, pumping, thermodynamics and heat transfer worked as dairy plant problems.
In the exams: ICAR AICE subject 38 Units 1 and 4; ICAR AIEEA-PG group 17 Unit III (fluid mechanics, pumps, heat transfer, thermodynamics, dimensional analysis); GATE XL-U Section 4; GATE AG dairy and food engineering
How our questions for ICAR AIEEA-PG spread across the units of Fluid Flow, Thermodynamics & Heat Transfer in Dairy Plants. Difficulty: 12 easy, 64 medium, 3 hard.
| Fluid properties and Bernoulli's equation | 9 | |
| Pipe flow, Reynolds number and friction losses | 9 | |
| Sanitary centrifugal and positive displacement pumps; pump selection | 8 | |
| Laws of thermodynamics; steam tables | 7 | |
| Conduction, convection and radiation | 7 | |
| Heat exchangers: LMTD and effectiveness-NTU | 7 | |
| Dimensionless numbers and dimensional analysis | 7 | |
| Mass and energy balances in dairy processes | 7 | |
| Flow of non-Newtonian dairy fluids | 6 | |
| Fins and insulation | 6 | |
| Diffusion and mass transfer coefficients | 6 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
In Bernoulli's equation written in head form, the term v²/2g represents:
A. Velocity head
p/ρg is pressure head, z elevation head, v²/2g velocity head; friction losses are added for real flow.
Further reading: Singh and Heldman, Introduction to Food Engineering
Pipe flow is generally laminar when the Reynolds number is below about:
B. 2,100
Below about 2,100–2,300 laminar; above about 4,000 turbulent.
Further reading: Singh and Heldman, Introduction to Food Engineering
How much heat is needed to warm 5,000 kg/h of milk (c_p = 3.9 kJ/kg K) from 60 °C to 90 °C?
D. 162.5 kW
Q = ṁc_pΔT = 5,000 × 3.9 × 30 = 585,000 kJ/h = 162.5 kW. Using water's c_p gives 174.2 kW.
Further reading: Singh and Heldman, Introduction to Food Engineering
Air left in a steam sterilising chamber is harmful mainly because:
C. It lowers the temperature at that pressure
The temperature depends on steam partial pressure; air pockets give cold spots.
Further reading: Steam tables
In a counter-current exchanger, hot water enters at 90 °C and leaves at 80 °C; milk enters at 60 °C and leaves at 75 °C. The LMTD is:
C. 17.4 K
ΔT₁ = 90 − 75 = 15 K, ΔT₂ = 80 − 60 = 20 K; LMTD = 5/ln(20/15) = 17.4 K, slightly below the arithmetic mean of 17.5 K.
Further reading: Singh and Heldman, Introduction to Food Engineering
Raw milk enters a pasteuriser at 4 °C and leaves the regenerator at 66 °C; pasteurisation is at 72 °C. The regeneration efficiency is:
A. 91%
η_R = (66 − 4)/(72 − 4) = 62/68 = 91%. Dividing by 72 forgets the inlet temperature.
Further reading: Tetra Pak Dairy Processing Handbook
Halving the thickness of a cheese reduces the time for salt to equalise by diffusion to about:
D. One quarter
Diffusion time scales with distance squared.
Further reading: Geankoplis, Transport Processes and Separation Process Principles
Which dimensionless number is used to characterise natural convection?
B. Grashof
Gr = gβΔTL³/ν² measures buoyancy against viscosity.
Further reading: Incropera et al., Fundamentals of Heat and Mass Transfer
10,000 kg/h of skim milk at 9% total solids is evaporated to 45% TS. How much water is removed?
C. 8,000 kg/h
Solids 900 kg/h; concentrate = 900/0.45 = 2,000 kg/h; water = 10,000 − 2,000 = 8,000 kg/h.
Further reading: Singh and Heldman, Introduction to Food Engineering
Multiple-effect evaporators save energy mainly because:
B. Vapour from one effect heats the next
Reusing latent heat in successive effects raises steam economy roughly in proportion to the number of effects.
Further reading: Singh and Heldman, Introduction to Food Engineering
Ten here, 79 in the app. The Laisha app has every practice question we have written to ICAR AIEEA-PG in this subject, marked as you go, with timed papers, a jump-to-unanswered list and a certificate when you pass at 70 per cent.
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