Name of the College : G. H. Raisoni College Of Engineering
Subject Code/Name : Energy Conversion –II
Dept : Mechanical Engineering
Degree : B.E
SEM: : VII
Website : raisoni.net
Document Type : Question Bank
Download Model/Sample Question Paper : https://www.pdfquestion.in/uploads/raisoni.net/3294-Document.doc
Raisoni Energy Conversion – II Question Paper
Reciprocating Air Compressors :
Unit – I
1. Describe the effect of intercooler in a two-stage air compressor.
2 A two-stage double acting air compressor operating at 200 r.p.m. Takes air in at bar and 270 C the diameter and stroke of L.P. cylinder are 35 cm & 38cm resp.
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The stroke of H.P. cylinder is same as L.P. cylinder and clearance of both the cylinders is 4% of the stroke .The L.P. cylinder discharges air at 4.052 bar. The air passes through the intercooler so that it enters the H.P. cylinder at 270 C and 3.85 bar. Finally the air is discharged from the compressor at 15.4bar. The compression and re-expansion in both cylinders follow the same law, pv1.3 =constant. Determine
i)Brake power required to run the compressor if mechanical efficiency is 80%
ii)The diameter of H.P. cylinder
iii) Heat rejected in intercooler.
3. Obtain an expression for the minimum work required for a two-stage reciprocating air compressor
4. Explain what is meant by volumetric efficiency of a compressor. Derive an expression for volumetric efficiency of a single stage air compressor.
5 . What do you mean by compressor? How are the compressors classified?
6. Explain why an isothermal process is considered for compressing air.
7. What is a reciprocating compressor? Draw a neat sketch of it.
8. Differentiate between single acting and double acting compressor.
9 Why multistage is done in reciprocating air compressor? Explain the importance of air-cooling in multi stage compressor. Also give advantages of multi stage over single stage compressor.
10. Derive the minimum work per kg of air delivered in two stage compressor with intercooler and without intercooler.
11. A 2-stage single acting reciprocating air compressor drawn 6kg/min 0of air at 1.013 bar and 293 K and the same is delivered at 14.75 bar. Assume perfect intercooling with compression index of 1.25. The clearance factor for low pressure and high pressure cylinder are 0.04 and 0.07. Determine 1. shaft power required with mechanical efficiency 85% 2.Isothermal efficiency 3. volumetric efficiency of each stage. 4. FAD.
12. A 2-stage reciprocating compressor takes air at the rate of 0.2 m3/sec. the intake pressure and temp. of air at 0.1MPa and 160 C. The air compressed to a final pressure of 0.7MPa. The inter-cooling is perfect. The compression index in both the stages is 1.25 and compressor runs at 600 rpm. Neglecting clearance determine 1. Intermediate pressure 2. Volume of each cylinder 3. Power required driving the compressor. Take mechanical efficiency 80% cp=1.005 Kj/kgK R=287 j/kg K.
13. 2-stage compressor delivers air at a rate of 1.5 kg/sec. the suction pressure is 1.013bar. the inter-stage pressure is 7bar and the delivery pressure is 45bar. Air enters the low-pressure cylinder at 280K and is niter cooled to 300K before inlet to the high pressure cylinder and delivers at 420K. The clearance volume of low pressure and high cylinders are 6% and 8% of the stroke volume. Assume law of compression and expansion same for low and high pressure cylinder. Determine 1. Swept volume of cylinder 2. Amount of heat removed in jacket cooling for each cylinder 3. The ideal power required to drive the compressor.
14 . Differentiate between reciprocating and rotary compressor
Unit – II
15. Air at a temperature of 170 C flows into the centrifugal compressor running at 20,000 rpm. Using the following given data:
Slip factor = 0.80
Work input factor = 1
Isentropic efficiency = 70%
Outer diameter of blade tip = 50 cm
Assuming the absolute velocities of air entering and leaving the compressor is same
Find: 1) The temperature rise of air passing through compressor &
2) The static pressure ratio
16. Write short notes on
i) Slip factor & pressure coefficient
ii) Surging and choking of compressor
iii) Degree of reaction in case of axial flow compressor;
iv) Pre-whirl of centrifugal compressor
17. Compare Roots blowers with vane blower in respect to :
i) Working principles
ii) P-V diagram
iii) Efficiency
18. Discuss with a neat sketch the working of a roots blower.
19. Describe with a neat sketch the working principle vane blower. Also give indicator diagram.
20. What do you mean by axial flow compressors? Explain its working principle with neat sketch.
Unit – III
24 Describe in short working of 4stroke and 2stroke petrol and diesel engine.
25 How IC engines are classified? Also how SI engine are classified by valve operation.
26 What do mean by detonation or knocking? What are its effects?
27 Draw a neat sketch of carburetor
28 Write short note on ignition system and spark plug.
29 Describe battery ignition system with a neat sketch.
30 What do you mean by scavenging? Show the process of scavenging of 2 stroke SI engine.
31. Draw a neat sketch of lubrication system used in automobile. Also explain it.
32. Write a short note on emission and pollution control measures in IC engine.
33. What are the factors limiting the performance of an IC engine.
34. What are different methods of finding the frictional power of IC engine? Explain morse test method and Williams line method.
35. Draw performance curve of an IC engine.