Assignment-Turbocharging

1. With the help of a p-V diagram of an ideal dual-cycle, explain the availability of the maximum possible work available which could be utilized for the purpose of turbocharging.

2. Explain the concept of turbocharging of an IC engine with the help of a neat diagram.

3. A four stroke, 8-cylinder turbocharged diesel engine has firing order 1-6-2-4-8-3-7-5. Duration of EV opening period=2600.Determine the exhaust pipe arrangement for the most economic and efficient operation.

4. A four stroke, 4-cylinder turbocharged diesel engine has firing order of 1-3-4-2. Duration of EV opening period for each cylinder is 2400. Draw a graph to show the exhaust manifold pressure variation with respect to crank angle. Show clearly on the graph the scavenging period during valve overlap and, the connecting of various exhaust pipes.

5. A four stroke, 12-cylinder turbocharged V-type diesel engine has firing order 1-5-3-6-2-4 and 6-2-4-1-5-3 for the other end. Duration of EV opening period=2400. Determine the exhaust pipe arrangement for the most economic and efficient operation.

6. Explain the principle of operation of Constant Pressure Turbocharging with the help of a diagram and also, the

exhaust pressure diagram. List out the advantages and the disadvantages of this system.

7. Explain the principle of operation of Pulse Turbocharging with the help of a diagram and also, the exhaust pressure diagram. List out the advantages and the disadvantages of this system.

8. Explain the principle of operation of Pulse convertor with the help of a diagram.How does this system exploit the advantages of both the constant pressure and pulse turbocharging?

9. Explain the concept of Free-piston engine (gas generator power plant) with the help of a neat layout diagram and the graph of charge pressure ratio vs. specific power output.

10. Why do we prefer axial/radial compressors over the reciprocating compressors for the purpose of turbocharging? And, why is radial compressor preferred over axial compressor for the same purpose?

11. Make a line diagram to show the construction of a centrifugal compressor. Mark all the parts clearly.

12. Explain the phenomenon of Compressor surge and stall (choking) with the help of a compressor map. Show the safe working range for a steady flow through the compressor.

13. Turbocharging has the adverse effect of increasing the temperature of the charge. What are the three ways in

which this happens? An after-charge cooler brings many benefits. Whar are these?

14. Explain the phenomenon of turbocharger lag. How is this problem solved with the help of a waste gate control valve? Explain with the help of a suitable neat diagram.

15. Figure shows the compressor map and the turbine characteristic (marked “A”) to be used on a turbocharged 4-stroke diesel engine. The following data is given:-

CV = 42000 kJ/kg.Heat loss to radiation and to coolant = 23% of heat supplied.Cpc= 1.05 kJ/kg.KRatio of Cp in turbine to compressor = 0.9Turbine efficiency = 0.7Inlet air = 1 bar, 293 K.K ((γ-1)/γ)= 0.286; R = 287 J/kg.KIndicated thermal efficiency of the engine = 0.42Volumetric efficiency = 0.9Swept volume = 10.3 litre = .0103 m3.Fuel injected per cycle = 0.952 g at full rack. =0.714 g at ¾ rack =0.476 g at ½ rack =0.238 g at ¼ rack

Calculate the matching conditions at full, ¾, 1/2 and ¼ rack and at speeds 2100, 1500, and at 1000 rpm.

16. A 4-stroke 12-cylinder diesel engine with bore = 7.2 cm, stroke = 9.4 cm and operates at 2500 rpm. The Volumetric efficiency = 1.18 and inlet conditions are 1 bar, 293 K. The compressor map and the turbine characteristic (marked “A”) are shown in the figure and a waste gate is fitted to limit the boost pressure to 2.4 bar. Indicated thermal efficiency of the engine is 0.44, Heat loss to radiation and to coolant = 22% of fuel energy.

CV = 42500 kJ/kg; Turbine efficiency = 0.72Cpa= 1.01 kJ/kg.K; Cpg= 1.21 kJ/kg.K; γa=1.4;

γg=1.3R = 287 J/kg.KExhaust gas pressure (p2) = 2 bar Engine fuel supply rate= 0.6 kg/min

Show that Pressure of the exhaust gases (p2) is 2 bar.

Determine the waste gate flow rate, air-fuel ratio and the brake mean effective pressure. Take friction mean effective pressure=1.8 bar