Thermal Engineering - II previous year question paper | 3351901 |

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Studying past papers are a valuable part of exam preparation and help keep revision focused on important themes whilst practicing exam style questions.

One of the simplest ways to prepare for the exams is to manage your study according to a well-defined time table and allot time to every subject. It is a good practice to compare the questions of the examiners because it will give a better idea about what the examiner is looking for in the exam.

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One of the most important part of exam preparation is going through past exams. It is important  to revise your entire syllabus quickly. They can provide you the general idea of the upcoming paper and you could easily guess the important topics of a particular subject. Past exam papers give you the idea of number of questions and the available choices. It is therefore necessary for students to give some time to go through the past paper while revising a subject.

Past exam papers are one of the most helpful tools available to prepare for both internal and external examinations as they provides students with practical insight into how the forthcoming exam paper is likely to look and the key themes or subject areas most likely to be covered. Before starting revision for a subject it is always worth taking time to seek out past papers.

Winter 2014 Thermal Engineering - II Question Paper

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GUJARAT TECHNOLOGICAL UNIVERSITY
Diploma Engineering - SEMESTER–V • Examination – WINTER • 2014
Subject Code: 3351901  Date: 26-11-2014
Subject Name: Thermal Engineering - II
Time: 10:30 am - 01:00 pm  Total Marks: 70

Instructions:
1.  Attempt all questions.
2.  Make suitable assumptions wherever necessary.
3.  Figures to the right indicate full marks.
4.  English version is considered to be Authentic.
5.  Use following table for Q.3 – b

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Q.1    Answer any seven out of ten.  14

1.  Write equation for thermal efficiency in terms of compression ratio with usual notations for CI and SI engine.

2.  Define Mean Effective Pressure (MEP) with mathematical equitation.

3.  Give any two SI unit for Mean Effective Pressure with inter relation.

4.  Draw  PV  and  TS  diagramme  with  name  of  process  (Mechanical  and Thermodynamics) for CI engine.

5.  Draw  PV  and  TS  diagramme  with  name  of  process  (Mechanical  and Thermodynamics) for SI engine.

6.  Define Refrigerant.

7.  Define Ton of refrigeration.  Write down  relation  between TR and  KW  from definition.

8.  Name any Two hello carbon refrigerant with its chemical formula.

9.  State equation of COP for reversed Carnot cycle with usual notations.

10.  Name any four expansion device used in VCRS.

Q.2  (a)  Draw  theoretical  and  actual  valve  timing  diagramme  for  four  stroke  diesel engine.   03

OR

(a)  Draw  theoretical  and  actual  valve  timing  diagramme  for  four  stroke  petrol engine.  03

(b)  Explain  reasons  for  difference  in  actual  and  theoretical  valve  timing diagramme for petrol engine.  03

OR

(b)  Explain  reasons  for  difference  in  actual  and  theoretical  valve  timing diagramme for diesel engine.  03

(c)  List advantage and disadvantage of Liquid Hydrogen as a fuel.  04

OR

(c)  List advantage and disadvantage of LPG as a fuel.  04

(d)  Draw sketch for CNG supply system at gas station.  04

OR

(d)  List and explain various types of Alternative Fuels.  04

Q.3  (a)  A CI engine having break power is 25000 Watt, consume fuel 7.0 Kg/hr. Find Indicated  Thermal  Efficiency,  Break  Thermal  Efficiency,  Break  Power  and Specific Fuel Consumption based Break Power. The calorific value of fuel is  22000 KJ/Kg.   07

OR

(a)  Following observations are available during trial of four stroke single cylinder SI engine.
Diameter of Cylinder: 300mm 
Stroke: 500mm
Pressure Ratio: 6   
Mean Effective Pressure: 8 bar
Speed: 320 rpm     
Calorific Value of fuel: 21000 KJ/M3
Fuel consumption rate: 0.5 M3/min. 
Mechanical Efficiency: 70%
Find (1) Indicated Power (2) Break Power (3) Indicated Thermal Efficiency

(4) Cycle Efficiency (5) Specific Fuel Consumption based Break Power.   07

(b)  An  ammonia  refrigeration  system  (based  on  VCRS)  working  between
temperature  limits  of  -10oC  and  30o   ( 'o' = degree )

C.  The  vapour  is  95%  dry  at the  end  of compression  and  there  is  no  sub  cooling  of  refrigerant.  Using  table  in instruction, find Compressor work, Heat rejected by condenser, Refrigerating effect and COP per Kg of refrigerant.  07

OR

(b)  In a 15 TR Ammonia refrigeration plant, the condensing temperature is 30oC and  evaporating  temperature  is  -10o   ( 'o' = degree )

C.  The  refrigerant  leaving  evaporator  is dry and saturated and there is no sub cooling take place in condenser. Find out COP and power required to drive the system. Use table given in instruction. Take Cp for Ammonia vapor as 2.8 KJ/KgoK.   07

Q.4  (a)  Draw schematic diagramme of VCRS with name of each component.  03

OR

(a)  Explain Reverse Brayton Cycle with PV and TS diagramme.  03

(b)  Draw T-S and P-h chart for standard VCRS with name of thermodynamic and mechanical process.  04

OR

(b)  For  Reverse  Brayton  cycle,  derive  equation  for  cycle  COP  with  usual notations.   04

(c)  Draw Vapour Absorption Refrigeration System. Explain it with working and advantage.   07

Q.5  (a)  Draw Psychometric chart. Indicate all properties on it clearly.  04

(b)  Write down Carriers equation for partial pressure of water vapour in moist air with name and unit of notation used in equation.   04

(c)  Define (1) Humidity Ratio (2) Absolute Humidity (3) Relative Humidity   03

(d)  Draw Window Air Conditioner with name of all components.  03

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Summer 2015 Thermal Engineering - II Question Paper

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GUJARAT TECHNOLOGICAL UNIVERSITY
DIPLOMA ENGINEERING – SEMESTER –  • EXAMINATION – Summer 2015
Subject Code:3351901  Date: 01/05 /2015
Subject Name: THERMAL ENGINEERING-II
Time: 2:30 pm to 5:00 pm  Total Marks: 70

Instructions:
1.  Attempt all questions.
2.  Make Suitable assumptions wherever necessary.
3.  Figures to the right indicate full marks.
4.  Use of programmable & Communication aids are strictly prohibited.
5.  Use of only simple calculator is permitted in Mathematics.
6.  English version is authentic.

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Q.1    Answer any seven out of ten.  14

1.  Classify I C Engine.

2.  List reasons for failing a spark plug.

3.  Write advantages of Air-cooled engine.

4.  List various types of alternative fuels.

5.  Define C O P of refrigeration.

6.  Explain working of capillary tube.

7.  Mention chemical name and chemical formula of refrigerant R-12 and R-22

8.  Define Air-conditioning

9.  Explain Dew point temperature on T-S diagram.

10.  Explain working of condenser.

Q.2  (a)  Define following terms used for I C Engine:
(i)  Top Dead Centre (ii) Clearance Volume (iii) Compression Ratio  03

OR

(a)  Derive the equation for Brake Power from rope brake dynamometer.  03

(b)   Explain the reason for the need of alternative fuels.  03

OR

(b)  Explain Biodiesel as an alternative fuel.  03

(c)  Differentiate between two stroke engine and four stroke engine.  04

OR

(c)  Differentiate between S I Engine and C I Engine.  04

(d)  The following data was recorded during a test run made on a single cylinder, four stroke engines having a compression ratio of 6.
(i)  Bore and stroke = 10 cm and 12.5 cm respectively
(ii)  Dead load and spring balance reading = 60 N and 20 N
(iii)  Effective radius of brake drum = 40 cm
(iv)  Fuel consumption = 1.2 kg/hr
(v)  Calorific value of fuel = 42500 kJ/kg,
If the engine turns 2000 rpm and the indicated mean effective pressure is 0.25 MPa, determine its Indicated Power (I P), Brake Power (B P), Mechanical Efficiency (ηm) and Overall Efficiency (ηo).     04

OR

(d)  In a diesel engine fuel consumption is 6.5 kg/hr. If engine brake power is 22.4 kW and  mechanical efficiency is 75%, calculate the following;  (Take CV=21500kJ/kg)    04
(i)  Indicated Power
(ii) Indicated Thermal Efficiency
(ii) Brake Thermal Efficiency
(iv) Specific Fuel Consumption for B P

Q.3  (a)  “Theoretical valve timing diagram and actual valve timing diagram are different.” Explain with reason.  03

OR

(a)  List the advantages of MPFI system.  03

(b)  Define (i) Flash Point (ii) Fire Point (iii) Pour Point  03

OR

(b)  List the advantages of CNG as an alternative fuel.  03

(c)  Explain the vapor compression cycle on P-V, T-S, and P-h diagram with its 04

OR

(c)  Compare Hermetically sealed compressor with open compressor.   04

(d)  Define following terms;
(i)  Dry bulb temperature
(ii) Wet bulb temperature
(ii)  Humidity ratio
(iv) Relative humidity   04

OR

(d)  Show the following processes on psychometric chart and explain;
(i)  Heating with Humidification
(ii) Cooling with Dehumidification  04

Q.4  (a)  Explain splash lubrication system for IC Engines.  03

OR

(a)  List safety precautions in IC Engine.  03

(b)  Explain Dry Expansion (DX) evaporator in detail.  04

OR

(b)  Explain Automatic Expansion valve in detail.  04

(c)  The temperature limits of an Ammonia refrigerating system are 25°C and −10°C.  If  the  gas  is  dry  at  the  end  of  compression  and  there  is  no  under cooling of the liquid Ammonia. Plot the system on T-S and P-h diagram, and calculate the COP of the cycle. Use the following table for properties of ammonia   07

Q.5  (a)  Explain split Air-conditioning system with neat sketch.  04

(b)   State advantages, limitations and applications of vane type axial fan.  04

(c)  State purpose of governing and write brief note on quality governing.  03

(d)  List the factors affecting the location of cold storage.  03

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Winter 2015 Thermal Engineering - II Question Paper

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GUJARAT TECHNOLOGICAL UNIVERSITY
DIPLOMA ENGINEERING – SEMESTER – V-EXAMINATION – WINTER 2015
Subject Code: 3351901  Date: 19/12/2015
Subject Name: Thermal Engineering II
Time: 10:30 AM TO 1:00 PM  Total Marks: 70

Instructions:
1.  Attempt all questions.
2.  Make Suitable assumptions wherever necessary.
3.  Figures to the right indicate full marks.
4.  Use of programmable & Communication aids are strictly prohibited.
5.  Use of only simple calculator is permitted in Mathematics.
6.  English version is authentic.

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Q.1 Answer any seven out of ten.   14

1.  Define supercharging and scavenging

2.  State the function of crank shaft and flywheel in I.C. Engine.

3.  Define mean effective pressure and brake power of an I.C. Engine.

4.  Write two functions of fuel pump.

5.  Write four advantages of common rail direct injection system for diesel engine.

6.  Why we need alternative fuels?

7.  Define refrigerator and air conditioning.

8.  Define ton of refrigeration and coefficient of performance.

9.  Name any four thermal insulation used in vapor compression refrigeration system?

10.  Define relative humidity and dew point temperature?

Q.2  (a)  What are the different problems to be faced while using alternative fuels?  03

OR

(a)  What is CNG?  State its advantages?  03

(b)  Discuss the safety issue while using CNG and LPG as fuels.  03

OR

(b)  Discuss the effect of emitted gases in atmosphere?  03

(c)  Differentiate between two stroke and four stroke cycle I.C.Engine.  04

OR

(c)  Differentiate between C.I. and S.I. engine.  04

(d)  State the purpose of governing of I.C. Engine and explain any one method of governing of I.C. Engine.  04

OR

(d)  Draw theoretical and actual valve timing diagram for four stroke petrol engine.   04

Q.3  (a)  Give classification of refrigerants.  03

OR

(a)  List properties of refrigerants.  03

(b)  List different evaporator used in VCRS and explain any one?   03

OR

(b)  List different expansion devices used in VCRS and explain any one?   03

(c)  For bell Coleman cycle, derive equation for cycle COP with usual notations?  04

OR

(c)  Draw schematic diagram of VCRS and state function of each component?  04

(d)  Explain the working of water cooler?  04

OR

(d)  Draw schematic diagram of simple vapor absorption system and explain its working?   04

Q.4  (a)  Define following terms. 1] humidity 2] wet bulb temperature 3] degree of saturation   03

OR

(a)  Explain cooling and dehumidification process on psychometric process chart?   03

(b)  Draw diagram of split air conditioner showing all components?  04

OR

(b)  List types of air conditioning fans used in air conditioning?  04

(c)  The following observations were recorded during a test on single cylinder, low speed, four stroke cycle oil engines, having a bore of 30 cm and stroke   07 of 45 cm.
Speed =300 RPM,
Mean effective pressure = 5 bar,
Brake drum diameter = 1.8 m,
Brake rope diameter = 2 cm,
Net brake load = 1.5 KN.
Find 1] Indicated power 2] Brake power 3] Mechanical efficiency.

Q.5  (a)  In a theoretical cycle, condensing temperature is 380C. The refrigerant used is R12. If the evaporation temperature is -70C then calculate C.O.P. of the cycle. Enthalpy of refrigerant leaving the compressor is 407 KJ/Kg.

(b)  A certain air has DBT of 300C and WBT of 200C. Calculate the following using psychometric chart.
1] Relative Humidity 2] Enthalpy 3] Specific humidity 4] Dew point  temperature   04

(c)  Explain the effect of subcooling and superheating on performance of VCRS?  03

(d)  List various systems of an I.C.Engine.  03

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Summer 2016 Thermal Engineering - II Question Paper

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GUJARAT TECHNOLOGICAL UNIVERSITY
DIPLOMA ENGINEERING – SEMESTER – V• EXAMINATION – SUMMER 2016
Subject Code: 3351901  Date:07/05/2016
Subject Name: Thermal Engineering - II
Time: 02:30 PM to 05:00 PM  Total Marks: 70

Instructions:
1.  Attempt all questions.
2.  Make Suitable assumptions wherever necessary.
3.  Figures to the right indicate full marks.
4.  Use of programmable & Communication aids are strictly prohibited.
5.  Use of only simple calculator is permitted in Mathematics.
6.  English version is authentic.

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Q.1 Answer any seven out of ten.   14

1.  State functions of piston ring and fly wheel for I C Engine.

2.  Define (i) stroke volume (ii) compression ratio

3.  What is supercharging?

4.  State properties of CNG.

5.  State reasons for requirements of alternative fuels.

6.  Define (i) C O P of refrigerator (ii) C O P of heat pump

7.  State chemical formula of R-11 and R-12 refrigerant.

8.  State purpose of compressor in refrigeration system.

9.  1 bar = _________Pa = __________N/m2

10.  Define Air-conditioning.

Q.2  (a)  Explain fuel supply system for diesel system  03

OR

(a)  State the purpose of lubrication.  03

(b)  Classify I C Engine in detail.   03

OR

(b)  Define (i)Indicated power(ii) Mechanical efficiency(iii)Efficiency ratio    03

(c)  Differentiate between 2-stroke and 4-stroke engine.  04

OR

(c)  Differentiate between S.I and C.I engine.  04

(d)  The following data was recorded during a test run made on a single cylinder, four stroke engines.
Bore and stroke = 10 cm and 12.5 cm respectively
Dead load and spring balance reading = 60 N and 20 N
Effective radius of brake drum = 40 cm
Speed of engine = 2000 rpm
Indicated mean effective pressure = 0.25 MPa
Determine (i) Indicated Power (ii) Brake power (iii) Mechanical efficiency   04

OR

(d)  The following particulars refer to a 4-cylinder, 4-stroke petrol engine;
Bore and stroke = 65 mm and 95 mm respectively
Torque = 64 Nm, 
Engine speed = 3000 rpm
Determine brake mean effective pressure.   04

Q.3  (a)  Compare the air cooling and water cooling system for I.C. Engine  03

OR

(a)  State the reasons for failing a spark plug.  03

(b)  State safety precautions in I.C Engine.  03

OR

(b)  Draw valve timing diagram of 4-stroke C I engine.   03

(c)  Define (i) Flash point (ii) Fire point (iii) Pour point (iv) Freezing point   04

OR

(c)  Write short note on Biodiesel.  04

(d)  Explain reversed Carnot cycle for vapour medium on P-V and T-S diagram.    04

OR

(d)  Explain vapour compression cycle on P-V, T-S and P-h diagram.  04

Q.4  (a)  Compare between Hermetically sealed compressor and open compressor.   03

OR

(a)  Differentiate between Dry expansion evaporator and Flooded evaporator.   03

(b)  Explain vapour absorption refrigeration system with neat sketch.  04

OR

(b)  State the factors affecting the location of the cold storage.  04

(c)  A refrigerator operates on a reversed Carnot cycle whose C O P is 5.0. The evaporator is maintained at a temperature of  −6°C and the power required to run the refrigerator is 3.5 kW. Determine the refrigerating effect (RE) and the condenser temperature of the refrigerator.   07

Q.5  (a)  Define (i) Psychrometry (ii) Wet bulb temperature (iii) Dew point temperature (iv) Specific humidity   04

(b)  Explain heating with humidification process on psychrometric chart.   04

(c)  Explain the working of window air conditioner.  03

(d)  Differentiate between air conditioner and air cooler.  03

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Winter 2016 Thermal Engineering - II Question Paper

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GUJARAT TECHNOLOGICAL UNIVERSITY
DIPLOMA ENGINEERING – SEMESTER – V • EXAMINATION – WINTER 2016
Subject Code:  3351901     Date: 18- 11- 2016
Subject Name:  Thermal Engineering - II
Time: 10:30 AM TO 01:00 PM  Total Marks: 70

Instructions:
1.  Attempt all questions.
2.  Make Suitable assumptions wherever necessary.
3.  Figures to the right indicate full marks.
4.  English version is authentic.

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Q.1    Answer any seven out of ten.   14

1.  Explain the need of supercharging in IC Engine.

2.  Define mean effective pressure of an engine.

3.  State function of (i) Carburettor (ii) fly wheel

4.  What is CNG ? State four advantages of CNG as fuel.

5.  Name the parts of IC Engine which require lubrication.

6.  Define Net refrigerating effect.

7.  State equation of COP for reversed Joule cycle.

8.  What is Air-conditioning ? Classify it.

9.  What is Bharat Stage ? Explain it.

10.  What is psychometry ? Enlist various psychometric process.

Q.2  (a)Classify Internal Combustion engine.  03

OR

(a)  Differentiate  four stroke and Two stroke engine  03

(b)  State the methods of IC engine cooling and describe the water jacket system of cooling with sketch   03

OR

(b)  Explain battery coil ignition system of SI engine with sketch.  03

(c)Explain the working of fuel pump with neat sketch.   04

OR

(c)Explain the working of two stroke petrol engine with neat sketch.  04

(d)  State different types of scavenging methods and explain cross flow scavenging.   04

OR

(d)Expl ain the working of four stroke diesel engine with sketch.   04

Q.3  (a)  Following observations refer to the test of two stroke single cylinder engine
Mean effective pressure : 550 kpa    Bore : 21cm
Piston Stroke : 28 cm     
Speed : 6 R.P.S.
Braake torque: 628 Nm   
Fuel Consumption: 8.16 kg/h
Caloific value of fuel : 42700 kJ/kg
Find Mechanical Efficiency,Indicated Thermal Efficiency,Brake Thermal Efficiency and Brake specific fuel consumption.    07

OR 

(a)  During trial of four stroke single cylinder engine
Cylinder diameter : 0.3 m 
Stroke : 0.5 m
Compression ratio : 6.23 
mean effective pressure : 8 bar
Speed : 300 R.P.M.   
  Fuel consumption :25 m3/h
Calorific value of fuel : 21500 kJ/ m3
Find Indicated power , Indicated thermal efficiency ,Air standard efficiency  ( ϒ = 1.4) , relative efficiency.   07

(b)  Why need of Alternate fuels is arises ?  03

OR   

(b)  Describe advantages and disadvantages of Natural gas.  03

(c)  Describe working of window air conditioner with neat sketch.  04

OR

(c)  The dry bulb and wet bulb temperature of air are 210C and 180C respectively .Barometric pressure of air is 101.325 kPa.  Find partial pressure of water vapour if saturation pressure at WBT is 2.0643 kPa.  04

Q.4  (a)  Define (i) Dew point temperature (ii) specific humidity (iii) relative humidity  03

OR

(a)Enlist important points for maintenance of Air conditioners.  03

(b)  What is psychometric chart? Draw it and show four air properties lines and label it.   04

OR

(b)  Define any two (i) Refrigerant(ii) COP (iii) Ton of refrigeration  04

(c)  The  temperature  limit  of  an  ammonia  refrigerating  system  are  250C   and -100C  if  the  gas  is dry at the  end of compressor .calculate Net refrigerating effect and COP assuming no under cooling. Use values from Table.

Q.5  (a)  Explain the effect of subcooling of liquid and superheating of vapour on the performance of VCR system. Show the process on p-h diagram.    04

(b)  Expl ain the working of a water coo ler with neat sketch.  04

(c)State the desirable characteristics of refrigerant.   03

(d)Differentiate between wet and dry compression.   03

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