This project covers the design and analysis of a diesel and petrol engine powered car using a backward type of vehicle simulation.In this project 1.2l RITZ is used for gasoline and 1.2l for diesel .This two standard engines are altered to get high performance and low fuel consumption Three driving cycles are used to perform these issues. are FTP-75, NEDC and US 06 .
The diving cycle is programmed in the QQS toolbox which is used under MAT lab software .The optimization is done by changing the gear ratios. For each driving cycle fuel consumption and gear ratio graph is plotted for the 1.2 litre engine for both diesel vehicle and petrol version of vehicle, where the fuel consumption is plotted by the three cycles. For getting better fuel consumption optimization is done by changing the gear ratio for the same vehicle specification and the graphs are plotted for all the driving cycles.
Then the new vehicle and the selected vehicle are compared with the three cycles and according to which the fuel consumption and performance is studied. In the last part of the project the hybrid version of both diesel and petrol engine with in turn, a battery and a super capacitor is developed and analysed on the basis of performance and fuel consumption.
The design and performance of the car depends on fuel consumption, emission, power and torque. To get best possible Fuel consumption, Power & torque simulation is done. Simulation plays very important role in vehicle performance. Any simulation relies on the availability of accurate sub-models or good-quality test data from the components and on accurate portrayal of the physical and control linkages between the components.
Vehicle Simulation is also helpful in reducing the fuel consumption of the vehicle and reduces emission. Now a days there is strict norms of local emission commission due to increase in air pollution, each vehicle manufacturing company set their car according to the current drive cycle. These limits are calculated by the study of the standard engine performance over a complete driving cycle of a car.
There are several standard driving cycles which act as a benchmark for newly developed or developing cars in their regional areas of origin and performance. Various drive cycles such as ECE-15, FTP75, NEDC and US06 test cycle etc
Drive cycles have been developed by many country at present according to there respective driving. The widely used cycles were developed by United States, European community and Japan. FTP75 cycle is used in United states the "FTP-75" is a transient test cycle used for emission certification testing of cars and light duty trucks.
The "SC03" Supplemental Federal Test Procedure (SFTP) has been introduced to represent the engine load and emissions associated with the use of air conditioning units in vehicles certified over the FTP-75 test cycle.
The "US06" Supplemental Federal Test was developed to overcome the shortcomings with the FTP-75 test cycle in the representation of aggressive, high speed and/or high acceleration driving behaviour, rapid speed fluctuations, and driving behaviour following start up.
In European countries, the ECE+EUDC test cycle is performed on a chassis dynamometer. The cycle is used for emission certification of light duty vehicles in Europe. It is also known as the MVEG-A cycle.
In Japan the 10-15 mode cycle is currently used for emission certification and fuel economy for light duty vehicles and the 13-mode cycle for the testing of heavy duty engines.
1.2 New European Driving Cycle (NEDC)
The NEDC is the based on the approved official fig of cars. These values are compared with one specific car with the homologation values to ensure the indisputable condition of the vehicle.
The first part of the graph represents urban condition of driving, in which a vehicle is started in the morning and driven in stop-and-go rush hour time traffic. The second phase represents extra-urban driving with a max speed of 120 km/h
Figure 1: New European Driving Cycle
THERE ARE TWO NEDC Test:
COLD TEST AND HOT TEST
Cold test includes pollutants ,CO2 emission and fuel consumption
Hot test includes CO2 and fuel consumption.
1.3 FTP -75 driving cycle : The FTP-75 (Federal Test Procedure) has been used for emission certification of light duty vehicles in the U.S. The entire FTP-75 cycle consists of the following segments:
cold start phase
hot start phase
The following are basic parameters of the cycle:
Distance traveled: 11.04 miles (17.77 km)
Average speed: 21.2 mph (34.1 km/h).
Figure 2. FTP-75 Cycle
1.4 American US-06 driving cycle :
US06 driving cycle was made due to shortcomings of FTP75 test cycle, in the representation of aggressive, high speed and/or high acceleration driving behaviour , rapid speed fluctuations, and driving behaviour r following start up.
The cycle represents an 8.01 mile (12.8 km) route with an average speed of 48.4 miles/h (77.9 km/h), maximum speed 80.3 miles/h (129.2 km/h), and a duration of 596 seconds.
Figure 3. SFTP US06 Cycle
2. QUASI STATIC SIMULATION TOOLBOX
Quasi static simulation [QSS] toolbox is used to calculate the fuel consumption of the power train system. QSS toolbox allows the fast consumption estimation for most of the power train system.
Fig 4 QSS toolbox driving cycle program
In this QSS toolbox the program is designed as driving cycle, vehicle, manual gear, combustion engine tank, there is display in which the calculated value of fuel consumption is displayed . Each simulink have its calculation where we have to alter for it according to our vehicle specification. Three cycles US06,FTP75 and NEDC respectively are loaded in this QSS toolbox in which the where we can select the driving cycle according to the system.
2.1SELECTION OF CAR :
I have selected the 1.2L SKODA FABIA KOMBI for petrol engine and VW POLO 1.2 DIESEL engine for simulation
Skoda Fabia Kombi 1.2l petrol
VW POLO 1.2 DIESEL
GEAR RATIO FOR PETROL AND DIESEL ENGINE
Gear ratio Petrol
Gear ratio Diesel
3. Simulation of NEDC FOR PETROL ENGINE
The simulation of NEDC driving cycle is done for both PETROL and diesel engine. In this matlab the QSS tool box is selected. From that toolbox cycle NEDC cycle is selected. Then the values are input to vehicle box , manual gear box and combustion engine .
FIG 5 QSS block diagram petrol engine NEDC
After running the NEDC cycle We got output on display as 7.123 L/100 km fuel consumption. Input to each block was given based on the vehicle specifications selected for the standard car. Optimization for the same engine was done to get high performance for that engine. The main result of gear optimization is to minimize the fuel consumption of the engine.
3.1 OPTIMIZATION OF PETROL ENGINE WITH NEDC CYCLE:
FIG6 QSS block diagram petrol engine optimized NEDC
Fig7 Gear Ratio Vs Iteration NEDC
As from the above fig see that there is lots of fluctuation in value of gear ratio between 0-100 after that there is less fluctuation between 100-300 after that there is constant values from 320 an above.
FIG8 FIG 8 TORQUE Vs ANGULAR SPEED OF NEDC
In this graph we can see as the torque significantly increased at 90Nm and dips down at 85Nm then it again increase .
3.2. Explanation of gear optimization:
After completing gear optimization the fuel efficiency increased from 7.123 to 5.786 litre/100km.The performance of the car is improved. The gear ratio changed:
Old gear ratio
New gear ratio
4.Simulation of FTP 75
The simulation of FTP- 75 driving cycle is done for both gasoline and diesel engine. In this matlab the QSS tool box is selected. From that toolbox cycle American FTP- 75 is selected. Then the vehicle specification are put in the toolbox of vehicle, manual gear box and combustion engine. After putting the car gear values we get 7.123 l/100km efficiency.
FIG 9 QSS block diagram petrol engine FTP 65
4.1.OPTIMIZATION OF PETROL ENGINE WITH FTP 75 CYCLE:
After optimization of the cycle it was found increase in fuel efficiency and decrease in fuel consumption. Before the optimization fuel consumption was 5.69 litre/100km. As we can see there is significant increase in efficiency.
Fig10 torque vs angular speed of FTP75 PETROL
In this above graph there is increase in torque from 10Nm to 60 Nm after that at 80Nm the value of torque first increase and then decrease.
FIG11.Gear ratio Vs Iteration for FTP-75 PETROL
The gear ratio increases with 0 to 50 iteration which is 4 ,2.1, 1.4 ,1, 0.8 after that it gradually decrease and after 150 iterations the gear ratio is constant .
The new gear ratios after the optimization is
1st gear 2.5908,2nd gear 1.2429,3rd 1.0791,4th 1.10125,5th 1.0124.
5.Simulation of NEDC ON DIESEL ENGINE
The simulation of NEDC driving cycle is done for diesel engine. In this matlab the QSS tool box is selected. From that toolbox cycle NEDC cycle is selected. Then the values are input to vehicle box , manual gear box and combustion engine
After running the NEDC cycle We get output on display 6.315 litre /100km fuel consumption
5.1 OPTIMIZATION OF DIESEL ENGINE WITH NEDC CYCLE:
After optimization of the cycle, I found increase in fuel efficiency and decrease in fuel consumption.Before the optimization fuel consumption was 4.913lits/100km ,As we can see there is significant increase in efficiency from 6.315 litre/100KM to 4.913litre/100km.
Fig12 Torque vs angular speed of NEDC DIESEL
As from the above fig the value of torque decreases from 19Nm to 79Nm ,after that it the torque rapidely increase at 79Nm.
AFTER Gear Optimization NEW GEAR RATIOS ARE:
1ST GEAR 2.0556
2ND GEAR 0.9800
FIG13 Gear ratio Vs Iteration for NEDC DISEL
Trend in graph shows that all the gear ratio are decreased during the first 40 iterations than it slightly increases for 25 iteration and then it is constant for rest of the period.
Similarly Optimization of Diesel engine is done by using FTP-75 cycle.
We get following results.
Fuel consumption before optimisation 7.135lits /100km
Fuel consumption after optimization 5.539lits /100km
6. US 06 CYCLE
H:\GM engine testing\My question\us06\blck petrol us-06.jpg
FIG 14 QSS block diagram petrol engine US 06
For using US 06 cycle continuously variable transmission (CVT) is used . Continuously variable transmission (CVT) is a transmission which can change steplessly through an infinite number of effective gear ratios between maximum and minimum values. This contrasts with other mechanical transmissions that offer a fixed number of gear ratios. The flexibility of a CVT allows the driving shaft to maintain a constant angular velocity over a range of output velocities. This can provide better fuel efficiency than other transmissions by enabling the engine to run at its most efficient revolutions per minute (RPM) for a range of vehicle speeds
H:\GM engine testing\My question\us06\fuel comsumption.jpg
Fig15 fuel consumption
From the simulation results we found the fuel consumption value is 5.577lits/100Km .the above graph shows the overall fuel consumption over the cycle .The initial peak value is ignored because it represents the fuel consumption during the cold start of the vehicle. The value of the fuel consumption gets back to the normalised value after a few seconds of the operation of the vehicle. So, for this reason we take the mean value of the fuel consumption.
H:\GM engine testing\My question\us06\velocity.jpg
Fig16 velocity Vs time
The velocity graph is also plotted using a scope. The velocity graph above when compared to the standard US-06 driving cycle, shows similarities. Since, the results obtained from the simulation assures that the value of the fuel consumption complies with the real time fuel consumption values.
A hybrid vehicle is one that uses more than one type of propulsion. Today's hybrid vehicle incorporates the use of both petroleum based engine and an electric motor.
Series-hybrid system : In a series-hybrid system, the combustion engine drives an electric generator instead of directly driving the wheels. The generator provides power for the driving electric motors.
In series transmission batteries are most commonly used but these days super capacitors are replacing batteries because super capacitors have many advantages over conventional car batteries like they have Long life improved safety,environmental friendly ,high output power ,low cost Simple charge methods.
Super capacitors are still not widely used in place of battreries because of following drawbacks
amount of energy stored per unit weight is considerably lower,voltage varies with the energy stored High self-discharge
In hybrid vehicle simulation ,a series hybrid vehicle is selected as per required.
FIG 17 SERIES HYBRID
The series hybrid vehicle cycle is modelled by using QSS tool box by using both; a battery and a super capacitor one by one and simulation is done for both cases.
H:\GM engine testing\My question\nedc\diesel\hybrid.png
FIGURE 18.QSS BLOCK DIAGRAM OF HYBRID CAR USING BATTERY
The hybrid version of the diesel car as shown above and the results where obtained.Fuel efficiency of diesel car after optimization was 5.539lits/100km(NEDC).The fuel efficiency of hybrid car came to be 2.363lits/100km.The results shows there is significant increase in fuel efficiency of hybrid car than diesel car.
By the simulation of the three driving cycle done on the petrol and the diesel engine on the selected vehicle, it is shown that the diesel has a better fuel consumption than the petrol engine. The US 06 cycles show that CVT is suitable for the heavy loaded vehicle for both the engines, which is done at matlab. The new assumed petrol engine vehicle is also proved that it is equally better to the diesel engine of the selected vehicle. The optimized gear ratios selection proved to be more reliable and results from the real world. But the disadvantage of the new vehicle will be reduced in the acceleration power. Even though the acceleration power is reduced the fuel consumption is high which results in the low emission. In the hybrid vehicle battery is more efficient and fuel consumption than the super capacitor.
3.G. Cole, "Simple electric vehicle simulation (SIMPLEV) v3.1,"DOE Idaho National Eng. Lab.
4.W. W. Marr and W. J. Walsh, "Life-cycle cost evaluations of electric/hybrid vehicles," Energy Conversion Management, vol.33, no. 9
5.http://www.carfolio.com/specifications/models/car/?car=221133, pp. 849-853, 1992. 6.http://www.dieselnet.com/standards/cycles/ftp75.html