Question Bank - REFRIGERATION SYSTEM AND GAS DYNAMICS

 

QUESTION BANK

 

 

Question No.	Questions	Bloom’s Level
UNIT 1 - AIR and VAPOUR REFRIGERATION SYSTEMS
PART-A (Two Marks Questions)
1	What is meant by refrigeration and air conditioning?	BT2
2	Define the term ‘Unit of refrigeration’.	BT2
3	What is meant by relative COP?	BT2
4	Differentiate between heat engine, refrigerator and heat pump with formula.	BT4
5	What are the various types of refrigerators?	BT2
6	Explain the term “Tonne of refrigeration”.	BT2
7	A machine working on reversed Carnot cycle operates between 300C and     -150C. Determine COP, when it is operated as refrigerator.	BT4
8	A refrigerating machine working on reversed Carnot cycle consumes 6kW for producing refrigerating effect of 1000kJ/min. Determine the COP of machine.	BT4
9	What are the merits and demerits in air refrigeration system?	BT2
10	What are the various methods of air refrigeration system in aircrafts?	BT2
11	Describe the essential components of the refrigeration plant.	BT2
12	Draw the T-S and p-h diagram for vapour compression refrigeration systems.	BT4
13	List the different types of vapour compression refrigeration systems to improving the COP of simple cycle.	BT2
14	How to improve the COP in aqua-ammonia vapour absorption system?	BT3
15	Mention the refrigerant and absorbent in aqua-ammonia vapour absorption system and Li-Br vapour absorption system?	BT2
PART-B (Ten Marks Questions)
1	Derive the expression for air refrigeration system working on reversed Carnot cycle.	BT4
2	Derive the expression for air refrigeration system working on Bell-Coleman cycle.	BT4
3	In refrigerating plant, water at 20.50C is converting to producing as ice at -30C at 450kg per hour. Calculate the power required to drive the compressor for production of ice. Assume, latent heat of ice is 340 kJ/kg, specific heat of ice is 2.1kJ/kg.K.	BT5
4	A cold storage plant is required to store 20T of fish. The fish is supplied at a temperature of 25°C. The specific heat of fish above freezing point is 2.93kJ/kg.K. The specific heat of fish below freezing point is 1.25kJ/kg K. The fish is stored in cold storage which is maintained at -80C. The freezing point of fish is -30C. The latent heat offish is 232 kJ/kg and time taken to achieve cooling is within 8hrs. Find: (i) The capacity of the plant, (ii) Carnot COP between temperature range and (iii) Power required to run the plant, if the  actual C.O.P. of the plant is 0.33 times the Carnot C.O.P.	BT6
5	A refrigerator working on Bell-Coleman cycle operates between pressure limits of 1.05 bar and 8.5 bar. Air is drawn from the cold chamber at 100C, compressed and, then it is cooled to 300C before entering the expansion cylinder. The expansion and compression follows the law     PV1.3 = Constant. Determine the theoretical C.O.P of the system?	BT5
6	A vapour compression refrigerator works between the pressure limits of 60bar and 25bar. The working fluid is just dry at the end of compression and there is no under cooling of the liquid before the expansion valve. Determine: (i) dryness fraction, (ii) C.O.P of the cycle and capacity of the refrigerator, if the fluid is at the rate of 5kg/min. Pressure, bar   Sat. Temp. 0C   Enthalpy, kJ/kg Entropy, kJ/kg K   liquid vapour liquid vapour 60 295 151.96 293.29 0.554 1.0332 25 261 56.32 322.58 0.226 1.2464	BT4
7	A refrigeration plant using CO2 as refrigerant works between 250C and -50C. The dryness of CO2 is 0.6 at the entry of compressor. find the ice formed per day, if the ice is formed at 00C from water at 100C, quantity of CO2 circulated is 10kg/min. Take, Cpw=4.187kJ/kg0C, hfg=335kJ/kg, relative efficiency = 60%. Sat. Temp.0C Liquid heat (kJ/kg) Latent heat (kJ/kg) Liquid entropy (kJ/kg.K) 25 81.25 121.6 0.2513 -5 -7.53 245.8 -0.0419	BT5
8	Explain with a flow diagram, the working of aqua-ammonia vapour absorption refrigeration system and also mention how the COP is improved in it?	BT2
9	With a neat sketch, explain the working principle of Li Br-water absorption refrigeration system.	BT2
10	With a neat sketch, explain the working principle of a three fluid vapour absorption refrigeration system.	BT2

 

Question No.	Questions	Bloom’s Level
UNIT 2 – REFRIGERANTS, SYSTEM COMPONENTS and SPECIAL REFRIGERATION SYSTEMS
PART-A (Two Marks Questions)
1	List out some name of secondary refrigerants used in refrigeration systems.	BT2
2	How the refrigerants are classified?	BT4
3	State the desirable properties of ideal refrigerants.	BT2
4	Write the objectionable property of R717.	BT4
5	Explain the concept of greenhouse effect?	BT2
6	Explain the concept of global warning?	BT2
7	Explain ASHRAE numbering (designation) system for saturated hydro carbon refrigerants.	BT2
8	Explain ASHRAE numbering (designation) system for un-saturated hydro carbon refrigerants.	BT2
9	What is meant by isothermal refrigeration?	BT2
10	What is meant by non-isothermal refrigeration?	BT2
11	What is meant by ‘space refrigeration’?	BT2
12	What is meant by ‘process refrigeration’?	BT2
13	What is the basic principle of steam jet refrigeration system?	BT2
14	What is the basic principle of Hilsch tube refrigeration system?	BT2
15	State the classification of condensers used in refrigeration system?	BT2
PART-B (Ten Marks Questions)
1	Describe the desirable characteristics of ideal refrigerant. Explain how refrigerants are designated.	BT4
2	What is an azeotrope? Give some examples to indicate its importance.	BT4
3	Mention the chemical formula and the refrigerant number for following refrigerants:             (i)      Dichloro difluoro methane,      (ii) Dichloro tetrafluoro ethane, (iii)     Propylene,         (iv) Ethlylene     and       (v) Sulphur dioxide.	BT4
	Mention the chemical formula and the name of the refrigerant for the following refrigerants numbers: a.      (a) R11,     (b)   R30,     (c)   R123,     (d)   R744,    (e)   R729	BT4
4	Explain about physical, safe working and thermodynamic properties of a ideal refrigerant?	BT2
5	Describe the working principle and basic components of steam jet refrigeration system.	BT2
6	Explain the working principle and operation of Hilsch (vortex) tube refrigeration system.	BT2
7	Classify the types of compressor in refrigeration systems based on working principle.	BT4
8	Classify the types of compressor in refrigeration systems based on external drive.	BT4
9	Explain with neat sketch, the working principle of water cooled condenser.	BT4
10	Explain with neat sketch, the working principle of Air cooled condenser.	BT4

 

Question No.	Questions	Bloom’s Level
UNIT 3 –  AIR CONDITIONING SYSTEMS
PART-A (Two Marks Questions)
1	List out the various psychrometric properties of air.	BT2
2	Define the term moist air.	BT2
3	Define the term wet bulb temperature.	BT2
4	Define the term specific humidity.	BT2
5	Define the term sensible and latent heat.	BT2
6	Define the term relative humidity.	BT2
7	List out the various psychrometry processes.	BT2
8	Define the term sensible heat factor.	BT2
9	Define the term bypass factor.	BT2
10	Define the term air conditioning.
11	Classify air conditioning systems.	BT2
12	What are the factors affecting human comfort?	BT2
13	Define room sensible heat factor (RSHF).	BT2
14	Define grand sensible heat factor GSHF.	BT2
15	Define effective room sensible heat factor (ERSHF).	BT2
PART-B (Ten Marks Questions)
1	List out the various psychrometric properties of air and explain each.	BT2
2	Draw the psychrometric chart and explain the properties of psychrometry.	BT2
3	An air conditioning plant is required to supply 60 m of air per minute at a DBT of 21°C and 55% RH. The outside air is at DBT of 28°C and 60% RH. Determine the mass of water drained and capacity of the cooling coil. Assume the air conditioning plant first to dehumidify and then to cool the air.	BT4
4	The amount of air supplied to an air conditioned hall is 300m3/min. The atmospheric conditions are 35°C DBT and 55% RH. The required conditions are 20°C DBT and 60% RH. Find out the sensible heat and latent heat removed from the air per minute. Also find sensible heat factor for the system.	BT4
5	Explain the concept of sensible heat factor and bypass factor with suitable sketches?	BT2
6	Define the term human comfort, and explain the factors affecting the human comfort.	BT2
7	What is an effective temperature? State and explain the factors which govern optimum effective temperature?	BT2
8	Draw a labeled sketch and explain working of window air conditioning system?	BT2
9	Explain with neat sketch of split air conditioning system and what reason the system they split?	BT2
10	What are the equipments used in an air conditioning system and explain each with simple diagrams.	BT2

 

 

Question No.	Questions	Bloom’s Level
UNIT 4 – COMPRESSIBLE FLUID FLOW
PART-A (Two Marks Questions)
1	Define the term “compressible flow”.	BT2
2	Differentiate between compressible and incompressible flows.	BT2
3	What are the problems where compressibility effect has to be considered?	BT2
4	List the basic equations of compressible fluid flow.	BT2
5	Define the term “acoustic or sonic velocity”.	BT2
6	Define the term “Mach number”.	BT2
7	Find the velocity of a bullet fired in standard air if its Mach angle is 40° and take air temperature is 150C.	BT4
8	Define the term “zone of action”.	BT2
9	Define the term “zone of silence”.	BT2
10	Define the term “stagnation point”.	BT2
11	Name the types of shock waves.	BT2
12	When a shock wave is produced?	BT2
13	What are properties changes across a normal shock?	BT2
14	Give the difference between normal shock and oblique shock.	BT2
15	Show the normal shock in h-s diagram with the help of Rayleigh line and  Fanno Line	BT2
PART-B (Ten Marks Questions)
1	Derive the continuity equation, momentum equation for compressible flow and also derive Bernoulli’s equation for compressible flow undergoing isothermal process.	BT2
2	Find the sonic velocity for the following fluids: (i)                 Crude oil of specific gravity 0.8 and bulk modulus 1.5 GN/m2 (ii)               Mercury having a bulk modulus of 27 GN/m2.	BT4
3	An aeroplane is flying at a height of 14 km where temperature is – 45°C.       The speed of the plane is corresponding to M = 2. Find the sonic velocity and the speed of the plane. Take, R = 287 J/kg K and γ = 1.4	BT4
4	How are the disturbances in compressible fluid propagated?	BT2
5	A supersonic aircraft flies at an altitude of 1.8 km where temperature is 4°C. Determine the speed of the aircraft if its sound is heard 4 seconds after its passage over the head of an observer. Take R = 287 J/kg K and γ = 1.4	BT4
6	An aero plane is flying at 1000 km/h through still air having a pressure of 78.5 kN/m2 (abs.) and temperature – 8°C. Calculate on the stagnation point on the nose of the plane: (i) Stagnation pressure, (ii) Stagnation temperature, and (iii) Stagnation density. Take for air: R = 287 J/kg K and γ = 1.4	BT4
7	Air has a velocity of 1000 km/h at a pressure of 9.81kN/m2 in vaccum and a temperature of 47°C. Compute its stagnation properties and the local Mah number. Take atmospheric pressure =98.1kN/m2, R = 287 J/kg K and γ = 1.4.	BT4
8	Air at a pressure of 220 kN/m2 and temperature 27°C is moving at a velocity of 200 m/s. Calculate the stagnation pressure if (i) Compressibility is neglected ; (ii) Compressibility is accounted for. For air take R = 287 J/kg K, γ = 1.4	BT4
9	In aircraft flying at an altitude where the pressure was 35 kPa and temperature –38°C, stagnation pressure measured was 65.4 kPa. Calculate the speed of the aircraft. Take molecular weight of air as 28.	BT4
10	A supersonic nozzle is to be designed for air flow with Mach number 3 at the exit section which is 200 mm in diameter. The pressure and temperature of air at the nozzle exit are to be 7.85 kN/m2 and 200 K respectively. Determine the reservoir pressure, temperature and the throat area. Take: γ = 1.4	BT4

 

 

 

 

 

 

Question No.	Questions	Bloom’s Level
UNIT 5 – JET AND ROCKET PROPULSION
PART-A (Two Marks Questions)
1	Define the term thrust.	BT2
2	Define effective speed ratio.	BT2
3	Define the term specific thrust.	BT2
4	What is Thrust Specific Fuel Consumption (TSFC)?	BT2
5	Define the term propulsive efficiency.	BT2
6	What are the main parts of ramjet engine?	BT2
7	What are the various types of air breathing engine?	BT2
8	Define the term trust power or propulsive power.	BT2
9	Find optimum propulsive efficiency when the jet velocity is 500 m/s and flight velocity is 900 m/s.	BT4
10	Sketch the trust and propulsive efficiency variation against the speed ratio for a turbojet engine.	BT2
11	What is monopropellant? Give some examples for it.	BT2
12	What is meant by bipropellant?	BT1
13	Classify the rocket engines based on source of energy employed.	BT2
14	Define the term characteristic velocity.	BT2
15	Abbreviate the terms JATO and RATO.	BT2
PART-B (Ten Marks Questions)
1	Explain the construction and working of ramjet engine.	BT2
2	Explain the construction and working of pulse jet engine (flying bomb). Mention its merits and demerits.	BT2
3	Explain the construction and working of turbofan jet engine. Mention its merits and demerits.	BT2
4	Explain the construction and working of turbojet engine with indicator diagram. Mention its merits and demerits.	BT2
5	Explain the construction and working of turbo-prop jet engine. Mention its merits and demerits.	BT2
6	How the rocket engines are classified?	BT2
7	Explain the construction and working of liquid propellant rocket engines.	BT2
8	List out the various properties of liquid propellant and explain it.	BT2
9	Explain with neat sketch the working of gas pressure liquid propellant feed system.	BT2
10	Explain the construction and working of solid propellant rocket engines.	BT2

 

Note:                                                         Bloom’s Taxonomy

Bloom’s Level	Descriptions	Bloom’s Level	Descriptions
BT 1	Remember	BT 2	Understand
BT 3	Apply	BT 4	Analyze
BT 5	Evaluate	BT 6	Create

Prepared by Mr. R.Satheesh , Associate Professor

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