## NIFTEM-FOOD ENGINEERING-II-ENG 221- midterm + End Semester Question Paper Dec 2017- 4th Sem

*The information shared below is only to get a rough idea of NIFTEM’s end semester question paper pattern. However, questions proportion from the syllabus topics may vary every semester.*

# MIDTERM

**Important points-**

- Time- 1:30 hours
- Total Marks- 50
- Three parts A, B & C, in which Part A is compulsory of (15 marks) having Objective questions, MCQs, Fill in the blanks and matching type questions. Students have to answer the questions from Part-A on the paper itself. Time allotted for Part-A is 25 minutes
- Part B & part C consists of 25 marks and 10 marks respectively. Have to attempt -Part B- 5 questions of 5 marks each & Part C- 1 Questions of 10 marks. Time for Part-B and C is total of 01:05 hours.

**PART B **

**PART B**

### Answer any 8 questions from the following-

**1.** Discuss the following

*a) Critical Radius of insulation*

*(b) emissivity*

*(c) absorptivity*

*(d) LMTD *

*(e) steady-state heat transfer*

**2.** Draw the block diagram for forward feed and backward feed evaporator. Mention the applications of both.

**3.** Discuss falling film and rising film evaporator with their application in the food industry.

**4.** Discuss combined convection and conduction and overall coefficients with neat sketch and equations.

**5.** What are the objectives of drying?

**6.** Fresh carrots having 80% of moisture content (wb) are dried and water equal to twice the weight of the solid material present in fresh carrots is removed. The dried carrot thus produced is 240kg and has 200% moisture content (db). Calculate the quantity of fresh carrots dried.

**7.** Milk of 18.5 % TS is dried to 3.8 % moisture on a drum dryer at a rate of 10.5 kg of dried product/hr. The diameter of the drum is 60 cm and length 90 cm and the product is scrapped at 1/2 of a revolution. The steam temperature is 160°C and the vaporization point of the moisture is 104 °C. Find out the overall heat transfer coefficient. The latent heat at 104°C is 2260 kJ/kg.

.

**PART C**

### Answer any 1 question from the following-

**1.** A metal steam pipe having an outside diameter of 30mm has a surface temperature of 400 K and is to be insulated with an insulation having a thickness of 20 mm and a k of 0.08W/mK. The pipe is exposed to air at 300 K and a convection coefficient of 30 W/m^{2}K.

(a) Calculate the critical radius and the heat loss per m of length for the bare pipe.

(b) Calculate the heat loss of the insulated pipe assuming that the surface temperature of the pipe remains constant.

**2. **A triple effect evaporator is designed to reduce moisture from an incoming brine (NaCl + H_{2}0) stream from 70% (wt) to 5% (wt). If the evaporator unit is to produce 14670 kg/h of (NaCl +H_{2}O). The consumption of steam required is 355kg/h and the composition of NaCl in the solution leaving from the 1st and 2nd evaporator are 30% and 45% respectively. Draw a block diagram and determine the following:

(a) feed rate of brine in kg/h

(b) amount of moisture removed from each evaporator.

(c) amount of condensate produced

(d) steam economy.

# END SEM

**Important points-**

- Time- 3:00 hours
- Total Marks- 100
- Three parts A, B & C, in which Part A is compulsory of (30 marks) having Objective questions, MCQs, Fill in the blanks and matching type questions. Students have to answer the questions from Part-A on the paper itself. Time allotted for Part-A is 40 minutes
- Part B & part C consists of 40 marks and 30 marks respectively. Part B- 8 questions of 5 marks each & Part C- 3 Questions of 10 marks each. Time for Part-B and C is total of 2:20 hours.

**PART B **

### Answer any 8 questions from the following-

**1.** What is Fourier’s Law of heat conduction” What are its assumptions? Also, mention the explain features of Fourier’s law of heat conduction.

**2.** What is thermal conductivity, thermal resistance, overall heat transfer coefficient, and thermal diffusivity?

**3.** Describe with neat diagrams any two types of heat exchangers.

**4.** Derive an expression for Log Mean Temperature Difference for Counter Flow Heat Exchangers.

**5.** Define and distinguish Pasteurization and Sterilization.

**6.** With the help of the TDT curve describe the kinetics of microbial death.

**7.** With the help of a neat diagram describe the material and energy balance in a single effect evaporator.

**8. **With the help of a labeled diagram explain the working of twin drum dryers.

**9.** What is the Effectiveness of heat exchangers? Derive an expression for the effectiveness of parallel flow heat exchanger.

**10. **With the help of a neat sketch explain the working of Rising film evaporator.

**PART C**

### Answer any 3 questions from the following-

**1. **Describe the Critical thickness of insulation for cylindrical conductors, derive an expression for it, also discuss the dependence of heat flow on critical thickness for cylindrical conductors.

**2.** A cold storage room has walls made of 220 mm of brick on the outside, 90 mm of plastic foam, and finally 16mm of wood on the inside.

The outside and inside air temperatures are 25°C and -3°C respectively. If the inside and outside heat transfer coefficients are respectively 30 W/m^{2}°C and 11 W/m^{2}°C, the thermal conductivities of brick, foam and wood are 0.99, 0.022 and 0.17 W/m°C respectively, determine:

(a) The rate of heat removal by refrigeration, if the total wall area is 85m^{2}

(b) The temperature of the inside surface of the brick

**3. **Derive an expression for Log Mean Temperature Difference (LMTD) for counter-flow heat exchanger.

**4. **A steam pipe exposed to the atmosphere is to be covered with two layers of insulation each 3 cm thick. The average thermal conductivity of one of the insulation is 4 times that of the other.

Show that for a given temperature difference between steam and atmosphere, the location of better insulation should be next to the pipe surface.

**5.** **Define and distinguish:-**

1. Thin Layer drying and deep bed drying.

2. Constant rate period and falling rate period of drying.

3. Equilibrium Moisture Content and Critical Moisture content.

4. Absolute Humidity and Relative Humidity.

*Best of Luck !!*

See other papers

NIFTEM-Basic Chemistry- End Semester Question Paper Dec 2019- 1st year

NIFTEM-Basic Electrical Engineering- End Semester Question Paper Dec 2019- 1st year

NIFTEM-Physics- End Semester Question Paper Dec 2019- 1st year

*Source- Question Papers collected and provided by Soumen Roy*