Assignment 6

AIM :- To setup the turbocharger by using turbine and compressor data.

OBJECTIVES :-

Following are the objectives of this project are-

• To explore different Turbocharger with example from GT power.
• Compressor and Turbine plot
• Benifit of variable geometry turbine (VGT).
• Explore the Diesel VGT EGR modelling.

THEORY & INTRODUCTIONS :-

Advantage of Turbocharger :-

1. We can send compress air and we can achieve more power from the engine.
2. As we used exhaust kinetic energy to run turbine, this turbine rotate the compressor and we get more power.
3. It helps to reduce the BSFC I.e. Brake specific fuel consumption
4. As turbocharger compare with other engine in case of BSFC then obviously turbocharger is better with BSFC because of turbocharger use exhaust kinetic energy.

Naturally aspirated engine :-

Here is no force induction, the ambient air is sucked by the engine cylinder when piston travels towards the BDC it creates the vaccume that suck air from the ambient that air is burn and there is a exhaust which goes back the ambient and therefore it is called as the naturally aspirated engine. As this is the bigger engine, which causes entering more ambient air and required more fuels. As we know bigger engine have more power and torque while smaller engine have less power and torque. But for comparing the engine power and torque is not the right terminologies. It always compare with BMEP I.e. brake mean effective pressure. In case of naturally aspirated engine, we can use bigger size of engine but, it is not right approach then for right approach we need more air and for more air we need compressore which as follows-

Supercharger :-

Where engine directly suck the air from ambient there we put compressor to suck the air from ambient and compress it and it more denser and more air pass to the engine. Here more air enter into the engine so that more power we need and we get more power Let us say 200KW but, compressor has negative work and engine have positive work and for compressor working need some power let us say 25KW and so that get net power is 175KW.Still it is higher than natural aspirated engine because there we get only 100KW of power. Here we can not use exhaust kinetic energy. It is highly use in passanger car. The advantage of supercharger is only to produce instantaneous power at the time of engine start. In supercharger gasoline fuel generaly used.

Turbocharger engine :-

Here use turbine with compressor and use exhaust kinetic energy because turbine is work on the exhaust kinetic energy and produce kinetic energy.

Here ambient air goes to the compressor and compress air goes to the cylinder and it converts exhaust gas and this exhaust gas enter into the turbine and here air is expanded and goes to the atmosphere this is the turbine and this turbine is coupled to the compressor. Here for run the compressor we don’t need extra power and this compressor taken this power from turbine. This turbine run on exhaust kinetic energy on the principle of “Pulse”. In cylinder blow down air produces this blow down air goes to the turbine and turbine run the compressor. So here we get total power I.e. 200KW. The application of this engine is very widely I. e. in tractor engine, passanger car …etc.

The turbocharger is the only benifit that it taken the energy from engine and never gives power in the term of BSFC. It means it gives the benifit in case of BSFC as well.

Cut section of turbocharger :-

Turbocharger rotor runs at the very high speed I.e. 50,000 to 2,50,000 rpm in case of passanger car. It has two main components which are compressor and turbine. Compressor and turbine attach with shaft and for rotating this shaft we need oil or any coolant which dissipate the heat and goes to oil outlet. Here for single turbocharger has two turbine inlet and this type of configurations is called twins scroll turbine. The benifit of this turbine inlet that if we have more number of cylinders then half of them pass through each inlet and no interference occur.

Impeller :-

Blade have aerodynamic shape and such design is very critical. The main problem is here that durability because of due blade run at very high speed and chances of failure is very high. This components are very costly because of there have limited resources. Performance of turbocharger is directly proportional to exhaust kinetic energy. At the start of engine the engine speed is very low and if accelerator is press then exhaust kinetic energy is not available and this cause the turbolag.

Turbolag is nothing but the when we press the accelerator, exhaust kinetic energy is stop and no torque is available. This type of issue occre in passanger car. This type of error not occure in tractor engine.

Turbocharger technology trends :-

Major regions of a compressor map :-

Magneta lines represents the efficiency of the turbocharger and blue lines is called compressor wheel speed. Plot is in the middle have good but it have limitations to other sides. From this plot we can conclude that selection of compressor in suitable range is very benificial otherwise, there will be the chances of failure of compression and so that all the observation given out from that compression will fail. Here engine speed can not go above particular speed.

Fixed geometry :-

Energy comes in the exhaust and it goes to the turbine and turbine generates the power. It can not adjust the amount of kinetic energy. Here turbine can not change the kinetic energy once hardware is manufacture it.

Waste gate :-

Here, access amount of the energy bypass from the turbine. Here have arrangment called as pneumatic PID controller there is one end is compressor out and compressor pressure is going to the diaphragm on which we can set the pressure. When diaphragm activates then it open the wedge gate. Here we can control the amount of kinetic energy and therefore pressure remains constant. Here have the provision of bypassing some energy which going to the Turbine.

Compressor and Turbine MAP :-

If there have no compressor and turbine files then we can created by using compressor turbine map by pre-processing. These files are extension of *.trb and *.cmp. After creating these files we can use them anywhere to importing into the model. These files created by using designer data.

1. Compressor MAP :-

Here plot has pressure ratio vs mass flow rate. Inside the plot there have given points and thats points are called as Efficiency fraction. All range of efficiency are given here. In case of passenger car we can choose middle range of the efficiency but for that the quantity of pressure ratio and mass flow rate is very well as shown in above plot.

2. Turbine MAP :-

Here have different map which are according to engine speed and exhaust gassses. Here shown that at 3200 engine speed we get 2.8 pressure ratio. Also the turbine efficiency range varies from 10% to 80%. Mass ratio also in the range of 0 to 1.

Tutorial No. 6 geometry :-

1. Geometry :-

Here have twin entries I.e. 40 & 51, so it’s called “twins scrolled turbine”. First three cylinder enter into the first entry while another three cylinder have second entry as shown in the model. Every 120 degree turbocharger gives one pulse.

2. Engine cylinder geometry :-

Here always put default setting. Because here only we need to showing the model output by using turbocharger.

3. End enviornment Inlet boundary condition :-

This is the inlet boundary conditions, where default composition is air.

Absolute pressure = 2.4 bar Temperature = 400k

4. End enviornment outlet boundary condition :-

This is the outlet boundary conditions where pressure and temperature both quantities are increases as above. I.e.

Absolute pressure = 2.5 bar Temperature = 800k.

5. Case setup :-

The case setup run for only single case by taking engine speed = 3600rpm.

6. Engine geometry :-

Here, given different geometry which used to the engine I.e. bore, stroke, connecting rod length, no. Of cylinders, compression ratio…etc.

7. Engine operating conditions :-

Different data required for engine operating, that are given here.

8. Engine performance predictions :-

Here given basic output which need to analyse at the time of designing any components.

Brake power = 292 HP Air flow rate = 1093.3 kg/h Fuel flow rate = 51.8 kg/h BSFC = 238.1g/KW-h

9. Engine performance (Fuel energy basis) :-

Here given some basic energy like Fuel energy, Friction energy and Exhaust energy …etc.

10. Key cylinder predictions :-

Here given most important quantities I.e.

Burned residual mass = 2.7% EGR = 0% F/A ratio = 0.047 Lambda = 1.489 Fuel mass = 80 mg Maximum pressure = 118 bar Maximum temperature = 2005k

11. Fuel proparties :-

Here given values after diesel combustion and diesel vapourization-

Carbon atoms per molecules = 13.5 Hydrogen atoms per molecules = 23.6

Fuel heating value = 43.

12. Engine MEP, TOrque & power :-

Engine MEP = 17.6 bar Torque = 659.8 Nm Power = 248.7 KW

13. Pressure plot :-

Pressure is highest at combustion stroke I.e. power stroke or expansion stroke at TDC.

14. Temperature plot :-

Temperature also higher at power stroke because temperature is directly proportional to the pressure. Temperature increases from BDC to TDC and thereafter it decreases from TDC to BDC due to expansion and at intake valve it completely decreases as shown in above plot.

15. Burned fuel plot :-

Fuel is burned from compression stroke to power stroke from 0 degree to 60 deg upto 120 degree as shown in above plot.

Tutorial No. 7 geometry :-

1. Geometry :-

Here have one turbine and one compressor they are coupled by using shaft. Here two entries to the single turbine therefore it is called as “twin scroll turbine”. When there have more number of cylinders let us say more than four then this type of configuration always prefer in case of diesel engines. Sometime turbine energy is fixed, we can not change the turbine energy. Sometime kinetic energy of turbine also so high as we seen.

2. Turbine map :-

Here, we can modify turbine MAP values like,

Gas consant = 289 J/Kg-k Ratio of specific heat = 1.35 Maximum pressure ratio = 4

Maximum speed = 3600 rpm

3. Engine cylinder geometry :-

Here have given some basic input values which design the piston.

4. Shaft moment of inertia :-

Initial speed = 96000 rpm Shaft MI = 0.0005 Kg-m^2.

5. End enviornment inlet BC :-

Here inlet temperaturre and pressure are given here.

Absolute pressure = 1 bar Temperature = 298 k

6. End enviornment outlet BC :-

The boundary condition is same as that of inlet.

7. Case setup :-

Here created three different cases according to RPM, Altitude and mass fraction as shown above.

8. Compressor Plot :-

The black mark is shown on the plot that is the safest point on compressor. On that place compressor gives maximum output I.e. power but later on pressure increases and chances of compressor failure is increases.At different level different RPM quantities given so, by checking that We can understood the range of compressor.

9. Turbine plot :-

Here also shown turbine range from 0 to 3600. Turbine is best suitable for this engine speed within the range of pressure ratio 0 to 4. Turbine is more compactable for this range.

10. Engine geometry :-

Here given some basic geometries required to design piston, I.e. Bore, stroke, IVC, EVO, IVO and EVC…etc. All the geometry is in standerd format.

11. Engine operating conditions :-

Here given engine speed and according to that pressure, velocity, temperature …etc quantities are given.

12. Engine performance predictions :-

Here I decreases the mass of fuel in case set up then we get decreasing air flow rate and fuel flow rate. As altitude height increases, Brake power also decreases because, to go high altitude pressure & speed also decreases and thats why brake power also decreases.

13. Engine performance (Fuel energy basis) :-

Here given different engine speed on the basis of energy. Fuel, friction and Exhaust …etc different quantities are given here.

14. Key cylinder predictions :-

Here given different quantities like-

Burned residual mass = 2.5 % F/A ratio = 0.033 Lambda = 2.134

Fuel mass = 80 mg Maximum pressure = 174.62 bar Maximum temp = 1705k

15. Engine MEP, Torque and Power :-

MEP = 18.1 bar Torque = 678.4 Nm Power = 255.7 KW

16. Compressor/Turbine/Pump/Fan :-

Here given different turbine & compressor values are-

Speed is same for both but pressure ratio is varry, Compressor has maximum pressure ratio while Turbine has lower pressure ratio because of turbine doing the work while compressor not. Hence power and efficiency for turbine is more.

Variable geometry Turbocharger:-

Here have turbine wheels. When kinetic energy enters into the turbine so that turbine is ‘radialy in’ and ‘axialy out’. It means exhaust gasses enters radialy and before entering into the turbine there have some guiding vanes which we can see here that are moving and hence it is called as variable geometry turbocharger. Here vanes position changes contineously from zero to one. Here, zero means completely closed and 1 means completely open. Here obviously vanes never be closed some area must be required that’s why when it is zero then it never be zero. It depend upon the kinetic energy and pressure ratio we can change the amount of kinetic energy enter into the turbine.

1. Model selection :-

It is the example of Variable geometry turbine (VGT), the selection way as follows-

“File -> Example -> Engine 1D gas exchange combustion -> Diesel -> Diesel VGT EGR -> Diesel VGT EGR.gtm”

2. Geometry :-

Here turbine is coupled to the compressor with the help of shaft. How turbocharger will understand which rack position so for that we have this controller and VGT has electronic controller. Here recieve boost is used to sense the signals from different different parts. Setting of different different pressure at diferent different load conditions is not possible in fixed geometry so that, variable geometry turbocharger s used. Therefore this geometry is used in passanger car applications because of passanger car has main important is driving comfort zone there should not need lag therefore variable geometry turbocharger plays important role there. When we start the engine, maximum amount of kinetic energy pass into the turbine and it is the use of variable geometry turbocharger.

3. Output signal selector :-

4. Case setup :-

Here have multiple number of casses but I run only first 6 casses. This six casses for different engine speed, different target BMEP.

5. Engine geometry :-

Bore = 86 mm Stroke = 86 mm Connecting rod length = 129 mm

Compression ratio = 17.

6. Engine operating conditions :-

RPM = 4500, 4000, 3000, 2000, 1500 & 1000. According to this combustion start angle also varries.

Mean piston velocity = 42.3, 37.6, 28.2, 18.8 and 14.1 ft/sec.

7. Engine performance predictions :-

Here has different brake power, different torque, air flow rate and mass flow rate ..etc. According to that Brake efficiency also increases.

8. Engine performance (fuel energy basis) :-

Here given different engine speed on the basis of energy and %of fuel energy as given above. Fuel, brake, friction, exhaust …etc quantities are given.

9. Key cylinder predictions :-

Different Burned residual mass, EGR, Lambda, Fuel mass, Maximum temperature & pressure quantities are given here.

10. Engine MEP, Torque & power :-

For indicated RPM and crankshaft RPM,

MEP = 16 bar Torque = 254 Nm Power = 119.7 KW

11. Compressor/Turbine/Pump/Fan :-

Engine speed is same for both turbine & compressor. Pressure ratio higher for compressor due to no work output and pressure ratio for turbine is smaller because of work output is done. Mass flow rate, power and eficiency is smaller for compressor and higher for turbine as shown above. It also depends on engine speed.

12. PID controller plot :-

From above plot shows that PID output is 90% it means most of the part of variable geometry turbocharger is open and more air enters into the geometry.

13. Controller Dinject plot :-

Here fuel rate is 50%. Target BMEP and Actual BMEP is same here. Maximum fuel rate is more than target fuel rate.

14. Controller EGR plot :-

Here maximum throttle angle is very high. Actual EGR is in middle of the opening.

Actual EGR = 50 Max throttle angle = 90 Min throttle angle = 50

15. Controller turbo rack plot :-

Target and Actual boost pressure = 0.82 Maximum rack position = 1

Minimum rack position = 0.12

( 1 means full open valve and 0 means fully closed valve).

16. Compressor plot :-

The black point showing on the plot and that plot is in yielding zone it means that, data provided by manufacturer is somewhat outside the limit. For within the range of compressor it means its life is commenly high.

17. Turbine plot :-

Mass flow rate according to pressure ratio is good here. Our active turbine is within the range and providing the datails very suitable. The range of pressure ratio is 1 to 4 and reduced mass flow rate is 0 to 0.01395. This plot gives turbine efficiency which changes with respect to RPM.

CONCLUSIONS :-

From above challenge we can conclude that--

1. Naturally aspirated engine gives lower power because there are not use exhaust gasses.
2. Supercharger gives moderate power, but here is not available turbine so that compressor gives power from engine that’s why it reduces somewhat power.
3. Turbocharger has turbine so that, compressor gives power from turbine so that engine does not loose its power and we get maximum I.e. full power.
4. Fixed geometry turbocharger is used in passenger car so that we get maximum power because in this model we can use multiple number of supercharger and turbocharger.
5. Turbine and compressor’s efficiency depends on the mass fuel rate and engine speed.
6. As altitude height increases, Brake power and brake torque decreases but BSFC value increases.
7. In case of VGT, Turbine and compressor efficiency is in safer zone.
8. Turbocharger is superior than supercharger because of in turbocharger turbine is available to provide the power to compressor, and loading & engine speed capacity also higher in turbocharger.
9. Supercharger is used when start thrust is more and supercahrger is used when there have more loading conditions.
10. Turbocharger have only turbine lag problem, otherwise it’s suitable for any engine.

In this way I complete this challenge by providing all data and supercharger, turbocharger applications.