Cost Analysis With Improving Efficiency in Mechanical ...ijapie.org/Impdocs/Vol2/IJAPIE-2017-07-316.pdfAbstract : The main objective ... Regenerative braking is the phenomena of storing

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International journal of advanced production and industrial engineering

IJAPIE-2017-07-316, Vol 2 (3), 27-38

IJAPIE Connecting

Science & Technology withManagement.

A Journal for all

Products &Processes.

Cost Analysis With Improving Efficiency in Mechanical Kinetic Energy

Recovery System

Raghvendra Gautam*, Vipin Khandelwal, Vipul Nigam, Vivek Gemini , Vivek Dev

( Delhi Technological University, Delhi, India)

*Email: [email protected]

| IJAPIE | ISSN: 2455–8419 | www.ijapie.org | Vol. 2 | Issue. 3 | 2017 | 27 |

Abstract : The main objective of this paper is to design a Flywheel Based Kinetic Energy Recovery System for storing the kinetic

energy of a vehicle otherwise lost during braking and transmitting this stored energy to the drive train when the vehicle accelerates.

The rising fuel prices along with increased CO2 and NOx emissions prompted us to look into this area of research. This paper

provides a basic structure of the system and a driver program for the whole system. This research also studies the energy feasibility,

improvement in fuel efficiency and cost feasibility of the whole system. DS Solidworks has been used for designing the model.

MATLAB has been used for formulation of plots on Fuel Consumption. The driver program has been formulated on JAVA.

Improvement in fuel efficiency has been calculated for a drive cycle for Pune City.

Keywords : Flywheel Based Kinetic Energy Recovery System, Energy Feasibility, Improvement In Fuel Efficiency, Cost

Feasibility, Drive Cycle, Control System.

List of symbols :

m Mass of flywheel

I Moment of Inertia of Flywheel

r Radius of flywheel

ω Angular Velocity

v Peripheral Velocity

E Energy Stored In Flywheel

ρ Density of material of flywheel

ϭy Yield Strength Of flywheel

ϭh Hoop Stress in flywheel

M Mass of Vehicle

V Speed of Vehicle

Ev Energy of Vehicle

k Energy Coefficient

We Work done by Engine

Cf Calorific Value of fuel

mf Mass of fuel used

η Efficiency of Engine

D Diameter of flywheel

N Rotation Speed

T Thickness of flywheel

We Engine Work

I. MOTIVATION

Fossil fuels are consumed as a primary energy source in

transportation and industry. Currently, India consumes 4.16

million barrels of oil per day. Despite predictions that India

will exhaust its supply of oil in forty years, the demand is on

the increase, and is predicted to continue increasing, because

of the ever increasing population and demand for mobility.

The increasing demand of fuel to meet these needs inevitably

causes a rising of oil price [1].

India continued to increase its CO2 emissions to 2.47 billion

tonnes in 2015, which was 5.1% more than in 2014. This

growth rate is similar to the one observed for 2013 and 2007,

and a little below the average growth rate of 6.8% for the

2006–2015 period [2].

Price hike in fuel along with dwindling natural sources of

fossil fuels along with high Carbon Dioxide emissions are

reasons for adopting systems which save fuel in commercial

vehicles.

II. INTRODUCTION

Flywheel based Kinetic Energy Recovery Systems is a new

avenue in the vast field of Regenerative Braking.

Regenerative braking is the phenomena of storing the energy

(for reuse later) which is otherwise lost to the surrounding (in

the form of heat and sound) when brakes are applied [3].

The concept for the Flybrid flywheel Kinetic Energy

Recovery System (KERS) was originally developed by Jon

Hilton and his team when he was technical director of the

. Raghvendra Gautam et al.,

International Journal of Advanced Production and Industrial Engineering


engine division at Renault F1 in 2006. It is now being

brought to market by Silverstone based Flybrid Systems [4].

Every regenerative braking system requires 4 components.

1. An energy storage unit, i.e. flywheel.

2. A unit for engaging and disengaging the system with

main drive train, i.e. hydraulic clutch.

3. A governing unit to maintain a gradual supply of

energy during extraction, i.e. CVT.

4. A unit to monitor the whole system, i.e. control

system.

When brakes are applied in a car, kinetic energy of the

vehicle is dissipated in the heat energy produced in calipers

while braking. However, this kinetic energy of the vehicle

can be reused if a mechanism is provided to store this energy.

In a flywheel based KERS system, when the brake pedal is

pressed, a clutch engages with the flywheel system via a

CVT. The flywheel starts storing energy till it achieves a

constant rpm, this will reduce the speed of the vehicle and at

this point the flywheel gets disengaged from the drive train.

Now the calipers act and bring the car to rest. Now as the car

is idling, the flywheel rotates at a constant rpm.

When the brake pedal is released now, instead of coupling

with the engine, the drive train gets engaged to the flywheel

with the action of the friction clutch on the CVT.

The flywheel starts dissipating energy now, via the CVT to

clutch to the drive shaft. The flywheel dissipates energy and

its angular velocity keeps on decreasing. This decreasing

velocity can not be transferred to the axle directly. CVT

performs the function of a governor and provides a gradually

increasing energy supply to the drive shaft, hence driving the

car. Engine doesn’t put effort during this time and the

flywheel starts the car. This way engine work is reduced, and

fuel efficiency and mileage of the system increases [5,6].

Flywheel based systems have been used in Formula Cars

since 2009. Recently many transmission and gear box

manufacturers have started looking into this technology.

Torotrak, a UK based company has adopted this technology

and developed a system for buses, ships and other LMVs.

Their variation of this technology is called Flybrid and is now

being used in trucks manufactured by Ashok Leyland [7].

III. WORKING OF KERS MODEL

A suitable flywheel is used to store the Kinetic Energy of the

vehicle and A mechanism is developed for the proper

exchange of energy through the flywheel [8].

The Basic principle of working is,

When the brakes are applied, Flywheel takes a

fraction of the Kinetic energy that is to be wasted in

heat without KERS [9][10].

And during acceleration, the High energy Flywheel

supplies the excess energy required for increasing

the speed of the vehicle [9][10].

Detailed working of the KERS Model is as follows:

Storing Energy

When the brakes are applied, the engine clutch disengages

from the gear input shaft and drive shaft clutch engage with

the pulley of the CVT simultaneously. The obvious motion of

the drive shaft drives the layout shaft through the CVT, thus

driving the flywheel and Storing the Energy [10].

The engagement of clutch to the pulley is operated by a

hydraulic system, which receives a signal from the control

system, causing the movement of the arm attached to the

clutch resulting in the engagement of the clutch to the pulley

till the speed of the flywheel reaches the particular value of

rpm decided by the control system. The control system sends

a signal to the hydraulic system to disengage the clutch from

the pulley. Then the control system sends signal to finally

bring the calipers into action to fully stop the vehicle

[11][12].

Supplying Energy

When the vehicle is accelerating, flywheel clutch engages

with the transmission input shaft and the drive shaft clutch

also engages with CVT so both the engine and the flywheel

cause the vehicle to pick speed, here flywheel supplies the

additional energy to the drive shaft, thus reducing the load on

the engine [10].

The engagement of clutch with the CVT is operated by the

means of a hydraulic system, which works according to the

signals sent by control unit. When the energy of the flywheel

is utilized to the maximum extent, the control system

disengages the clutch from the CVT and then the vehicle is

solely run by the engine [11][12].

Fig 1: WORKING OF KERS MODEL




IV. ANALYSIS

1. The Flywheel is an energy storage device.

2. It stores energy in the form of kinetic energy.

3. It can store this energy without dissipation

because of its large inertia.

Ideally if a flywheel were made of rigid, incompressible,

non-deforming material it could store an infinite amount of

kinetic energy. This cannot be done in the actual case as

stresses are generated in the flywheel on rotation due to the

centrifugal force. These stresses deform the flywheel and

cause permanent failure when the hoop stress of flywheel

exceeds the yield strength of the flywheel.

Hoop Stress

Hoop stress is the circumferential stress induced in the

flywheel rim.

It is given by,

Ϭh=ρω2r

2 (i)

Or

Ϭh=ρv2 (ii)

Energy Stored in the Flywheel

The maximum energy that can be stored in the flywheel is

limited by the hoop stress exceeding beyond the yield

strength of material of flywheel.

Kinetic Energy stored in flywheel is given by,

E=⅟2 Iω2 (iii)

Now, technically speaking, Moment of Inertia I, depends on

moment of inertia of rim, hub and spokes of the flywheel.

Since, mass of flywheel is mostly concentrated on the rim,

the moment of inertia due to hubs and spokes can be

neglected.

Therefore, for the rim,

I=mr2 (iv)

Putting value of I in (iii)

E=⅟2mv2 (v)

And using (ii)

v2=Ϭh/ρ (vi)

E=⅟2mϬh/ρ (vii)

Factor Of Safety

Table 1: Materials

Material Name ρ

(gm/cc)

Ϭy(Mpa) Energy (kJ)

Aluminum 7075

T651

2.8 469 33.5m

Titanium Ti-6Al-4V,

STA

4.43 965 43.6m

Steel 4340, QT 7.7 1500 38.9m

AS4 carbo / epoxy 1.61 2111 262.2m

IM7 carbon / epoxy 1.61 2589 321.6m

IM9 carbon / epoxy 1.62 2993 369.5m

In normal operation and Flybrid Technology developed by

Torotrak, the permissible value of hoop stress is [13],

Ϭh= 0.40Ϭy (ix)

That is the factor of safety is kept 2.5 [13].

This is kept as such because if the factor of safety were to be

kept 1,

1. Flywheel would be on the verge of cracking and

peripheral velocity will be very high.

2. CVT will not be able to provide proper speed

reduction.

Therefore, from (viii) and (ix), Energy Stored in flywheel is

E=⅟2 m(0.40)(Ϭy/ρ) (x)

Now, therefore Energy stored in flywheel depends on the

material of flywheel and mass of flywheel.

Material of Flywheel

As can be seen from the equation for energy stored in the

flywheel, energy stored will be high for high Ϭy and low

density.

Table 1: Flywheel Material Properties [14]

The materials chosen for study are:-

1. Aluminum 7075 T651

2. Steel 4340, QT

3. AS4 carbon / epoxy

Mass Analysis

From (x) it can be seen that energy stored in flywheel is a

linear function with mass of flywheel and is directly

proportional to it, i.e. as mass of flywheel increases, energy

stored in flywheel increases.

E=km (xi)

Where k is a constant depending on the material of the

flywheel.

k=⅟2 (0.40)(Ϭy/ρ) (xii)

Case 1- No KERS used

Vehicle of mass, M reaches velocity, V in time, t.

All the energy of the vehicle is in the form of Kinetic Energy.

Ev=½MV2 (xiii)

There is only one source of energy, the engine.

We=η Cfmf (xiv)

Applying Energy Conservation,

Ev=We (xv)

Now, from (xiii), (xiv), (xv).

½MV2= η Cfmf (xvi)

And

mf=(½MV2)/ η Cf (xvii)

Case 2-KERS used

A vehicle of mass, M with a KERS system of mass, m

reaches velocity V in time, t. It starts from rest with

maximum permissible energy stored in flywheel.

All the energy in the vehicle is in the form of kinetic energy.

Ev=½(M+m)V2 (xviii)

There are 2 sources of energy powering the vehicle, the

engine and the KERS system.

E=km (xix)

We= η Cfmf (xx)

Applying Energy Conservation,

Ev=We+E (xxi)

Now, from (xix), (xx), (xxi)

½(M+m)V2-km= η Cfmf (xxii)




And

mf=[m{(V2/2)-k}+ ½MV

2]/ η Cf (xxiii)

Plots

The functions for mf for Case 1 and Case 2 were plotted

using MATLAB and the following things were studied.

Mass of Vehicle, M= 1100 kg (Average kerb weight of

running sedans)

Calorific Value of fuel, Cf= 43700 kJ/kg (Assuming Petrol

Engine)

Efficiency of Engine, η= 20%

3D surface graphs were plotted between m, V, mf.

The plots were made for different materials of flywheel,


2. Steel 4340, QT

3. AS4 carbon / epoxy

The main equations of the plots (mfvs V vs m) were:-

mf=[m{(V2/2)-k}+ ½MV

2]/ η Cf……with KERS

mf=(½MV2)/ η Cf…………….….without KERS

Fig 2: Plot 1: Aluminium 7075 T651, k=33.5 kJ/kg

Fig 3: Plot 2: Steel 4340, QT, k=38.9 kJ/kg




Fig 4: Plot 3: AS4 Carbon/Epoxy, k=262.2 kJ/kg

The WITH KERS surface for mf has a negative slope with

respect to mass of flywheel.

Hence, as mass of flywheel increases, fuel consumption

decreases, this is because energy stored in flywheel is directly

proportional to its mass.

Mass of flywheel cannot be more than 10kg, as force

required by clutch to press against the CVT will have to be

larger than 50kgwt to make this flywheel move. This is not

possible as the force applied on pedal by human multiplied

by mechanical advantage of a oil ram system, will have to be

larger than 50kgwt. A man can apply maximum force on

pedal equal to half his weight and the average weight of an

Indian driver is 80kg. Hence, he can only apply 40kgwt force

[15].

Hence, the weight of the flywheel is to be so selected such

that, force required to actuate clutch is small for the drivers

comfort, the flywheel energy is also sufficient, axial loads are

small etc.

Our system is closest in design to the Flybrid manufactured

by Torotrak.

The Flybrid system has been successful in foreign markets

and has been safely applied to hybrid vehicles. The mass of

flywheel in the Flybrid was 6kg, which was decided after

taking into account all the above constraints [16].

Hence, the mass of the flywheel decided for our system is

6kg.

m=6kg

Plot 4: mass of fuel v/s speed for m= 6kg

Fig 5: Graph plotted for V

This graph was plotted for

V=19.08-50m/s

That is 68km/hr to 180km/hr

The range was so chosen as the maximum permissible energy

in a flywheel corresponds to 68km/hr vehicle speed and

180km/hr [17] is the top speed of mainstream Indian sedans.

Dimension Calculation

From (ix) and (vi)

v=(0.40Ϭy/ρ)½

(xxiv)

There is an upper limit on ω due to mechanical constraints on

CVT.

Maximum permissible ω for the CVT in place is 20,000rpm

[18].

v= πDN/60 (xxv)

D= 60v/ πN (xxvi)

Given N=20,000rpm

ρ=m/volume (xxvii)

Volume=πD2T/4 (xxviii)




Table 2: Dimensions of Flywheel for materials

Name

of

Materi

al

Periph

eral

Velocit

y,v

(m/s)

Dens

ity

(kg/

m3)

mf

(k

g)

Volu

me of

Flywh

eel

(m3)

Diam

eter

(cm)

Thickn

ess

(cm)

Alumi

num

7075

T651

258.84 2800 6 0.002

14

24.7 4.7

Steel

4340,

QT

278.92 7700 6 0.000

77

26.6 1.3

AS4

carbon

/ epoxy

724.15 1610 6 0.003

72

69.1 0.99

From the table it can be seen that the diameter required for

AS4 Carbon is the largest and equal to about 70cm.

The KERS system to be used needs to be compact, as can be

seen from the design, the flywheel is in very compact

cohesion with the drive shaft, CVT.

Hence, it is not possible to accommodate a flywheel of 70cm

diameter in the KERS system, hence AS4 Carbon cannot be

used.

The materials, we have chosen for our KERS system are-


2. Steel 4340, QT

Energy Analysis

Energy analysis requires a step by step study of energy flow

in the system.

The following things need to be defined before proceeding

further.

Critical Speed, Vc- This is that speed of the vehicle which

gives it a Kinetic Energy equal to maximum kinetic energy

permissible in the flywheel.

½(M+m)Vc2=km (xxix)

Also, putting value of k

½(M+m)(0.20)Vc2=⅟2 m(0.40)(Ϭy/ρ) (xxx)

Therefore,

Vc= [2(Ϭy/ρ)m/(M+m)]0.5

(xxxi)

For Aluminium, it is 153.46 km/hr.

For Steel it is 165.37 km/hr

The KERS system works in the following manner.

Case 1- Vehicle starting from rest, no energy stored in the

flywheel.

The vehicle of mass, (M+m) starts from rest and engine does

work in bringing the vehicle to a velocity V.

Kinetic Energy of the car is given by,

½(M+m)V2 (xxxii)

Case 2- Vehicle undergoes braking and comes to rest.

Now some fraction of energy is stored in flywheel, and other

part is dissipated in the calipers.

This fraction is kept 20% of initial kinetic energy for given

Indian drive cycle for proper braking of the vehicle. This

fraction is altered by altering moment of inertia of drive train.

Hence, energy stored in flywheel due to braking is

0.20½(M+m)V2 (xxxiii)

Case 3-When vehicle starts from rest and reaches velocity V1,

with energy stored in the flywheel.

Energy stored in flywheel due to braking is

0.20½(M+m)V2 (xxxiv)

Now, final energy of vehicle,

½(M+m)V12= 0.20½(M+m)V

2+Engine Work

Engine Work is given by,

½(M+m)V12-0.20½(M+m)V

2 (xxxv)

Case 4-When vehicle is started from 0 and taken to a

velocity, V

And V>153.46 km/hr for Aluminium

And V>165.37 km/hr for Steel,

The energy stored in the flywheel on braking vehicle to 0 is

the maximum permissible energy in the flywheel and is given

by-

⅟2 m(0.40)(Ϭy/ρ) (xxxvi)

And is 201 kJ for Aluminium.

And is 233.4 kJ for Steel.

The rest of the excess energy is dissipated in the calipers,

while the energy in the flywheel is stored for the next

acceleration cycle.

Assumptions

1. There is no drag force.

2. Force due to rolling friction is negligible.

3. Clutch is always on full engagement.

4. No slip condition for clutch and CVT.

5. No mechanical losses.

6. No losses in the form of heat.

7. Engine is never switched off.

V. IMPROVEMENT IN FUEL EFFICIENCY

The main purpose of the Flywheel based KERS system is to

regenerate energy and use this to drive the vehicle. This will

help in improving the fuel efficiency of the vehicle.

Fuel Efficiency in automotive study is defined as how far a

vehicle can travel per unit of fuel. It is also called fuel

economy or mileage.

Fuel Efficiency/Mileage depends on the drive cycle of an

area.

Drive Cycle

Drive Cycle is the plot of vehicle speed vs time.

It gives the behavior of a vehicle in city roads.

A driver moves faster on open roads and has a lot of start

stop cycles in traffic congested areas.

A finite value of fuel efficiency cannot be derived for a given

vehicle. It always depends on the drive cycle [19].

Actual Drive Cycle

The drive cycle used is one given for Pune City. Pune city is

an important urban center in Maharashtra and a rapidly

growing metropolis of the country with highest two-wheelers.

With introduction of thousands of vehicles per month, the

traffic congestion in the city is increasing alarmingly. As a

consequence, average speeds on the city roads are greatly

impaired and range between 15 km/h and 35 km/h.

Extensive, time and speed data from five major roads

measuring approximately about 55 km from Pune city was

collected and the drive cycle plotted [20].




Fig 6:Drive Cycle 1: Drive Cycle For Pune City [21]

Fig 7: Drive Cycle 2: Drive Cycle For Pune City With Area Under Study

The period taken for study of fuel efficiency is taken enclosed in the red area. From 751 to 1151 seconds on the drive cycle

plot.

Fig 8: Area under study




Table 3: Energy in Flywheel

S N

o. Point

Speed

Process

Energy In

Flywheel

Energy Without

KERS (Kj)

Energy With KERS

(Kj) Km/Hr M/S

1 A 0 0

2 B 57 15.8 A-B Dissipated 137.82 138.5

3 C 10 2.77 B-C Stored 0 -26.86

4 D 33 9.16 C-D Dissipated 41.92 42.12

5 E 0 0 D-E Stored 0 -9.26

6 F 25 6.94 E-F Dissipated 26.4 26.53

7 G 0 0 F-G Stored 0 -5.32

8 H 33 9.16 G-H Dissipated 46.14 46.37

9 I 17 4.72 H-I Stored 0 -6.8

10 J 27 7.5 I-J Dissipated 18.68 18.77

11 K 0 0 J-K Stored 0 -6.22

12 L 17 4.72 K-L Dissipated 12.25 12.31

13 M 4 1.11 L-M Stored 0 -2.32

14 N 10 2.77 M-N Dissipated 3.54 3.55

15 O 0 0 N-O Stored 0 -0.84

16 P 51 14.2 O-P Dissipated 110.27 110.82

17 Q 40 11.1 P-Q Stored 0 -8.52

18 R 53 14.7 Q-R Dissipated 51.28 51.53

19 S 0 0 R-S Stored 0 -23.96

20 T 5 1.38 S-T Dissipated 1.04 1.04

Total=449.34 Total=361.44

Improvement In Fuel Efficiency

Fuel efficiency is calculated in a similar manner for this

graph as shown for the theoretical drive cycle.

A table is plotted for energy at all points for both the cases

for with and without KERS for the given drive cycle and the

fuel efficiency is calculated.

Work Done by Engine for no KERS is given by,

½MV2

Energy stored in flywheel for KERS system is given by,

0.20½(M+m)V2

Now fuel consumed without KERS,

Work Done By Engine= 449.34 kJ

Mass of Fuel Used, mf= (Work Done By Engine)/(ηCf)

Putting η=0.20

And Cf=43700 kJ/kg

mf= 51.4 gm

Fuel Efficiency= D/mf=D/51.4 km/gm

Now fuel consumed without KERS

Work done by engine=361.44kJ/kg

Mass of Fuel Used, mf= (Work Done By Engine)/(ηCf)

Putting η=0.20

And Cf=43700 kJ/kg

mf=41.3 gm

Fuel Efficiency= D/mf=D/41.3 km/gm

Percentage increase in Fuel Efficiency is given by-

= {(ηKers- ηNoKers)/ ηNoKers}x100

= {(D/41.3-D/51.4)/ (D/51.4)}x100 (Cutting D

above and below)

= {(51.4-41.3)/41.3}x100

=24.45%

Percentage increase in efficiency for the system comes out to

be 24.45%, when incorporated to mainstream sedan weighing

1100kg in Pune city.

The efficiency is calculated for the actual drive cycle, hence

it is convenient to say that the efficiency value calculated

holds good in practical situations and the incorporation of

this system to cars in the Indian market is a viable option.

VI. CONTROL SYSTEM

The function of the control is to take the input from the

speedometer, transducer and brake pedal and send signals to

the hydraulic system causing the engagement and

disengagement of drive shaft clutch and the brake calipers.

Also, the control system makes the required calculations and

the comparison of velocity during the braking and during the

starting of the vehicle.

Working

The control System is responsible for its work during

following two processes:

During Braking : When the brake is applied the brake pedal

send a signal 1 and the control system sends a signal 1 both

the signal passes through the XNOR gate give the signal 1 to

the control system 2 and program 1 is selected.(Consider the

Circuit Diagram)




During Starting :When the brake pedal is released it give

signal 0 to the control system and control system 1 provide

signal 0 to the XNOR gate and XNOR gate gives signal 1 to

the control system 2 and the program 2 get selected.

Fig 9: Control System Logic Circuit

Diagram

During Braking

Case1: when the 20% of total energy is less than Emax

Fig 10: Control system during braking

Equation to be followed:

½mv2=½Iῳ

2 + energy dissipated in calipers

½Iῳ2 =0.20 ½mv

2

• When speed of the flywheel is less than that of

required speed as calculated by the control system

considering 20% of the total energy to be store in

the flywheel clutch remain engaged to the CVT.

• As the speed of the flywheel becomes equal to the

required speed the clutch get disengaged and

calipers comes into action to bring the vehicle to

rest.

Case2: when the 20% of total energy is more or equal to Emax

Fig 11: Control system during braking

• When the speed of the vehicle is such that the 20%

of the total energy is greater than Emax then flywheel

stored only Emax and remaining energy dissipated in

the calipers.

• So when speed of flywheel is less than the vmax i.e.

speed of flywheel when it stores Emax energy, clutch

remains engaged with CVT

• When the speed of flywheel becomes equals to

vmaxthe clutch gets disengaged from CVT.

During Starting

Fig 12: During release of brake




• The flywheel will provide its energy to drive shaft

so that the vehicle can easily get started

• the clutch will remain engaged to the CVT till the

vehicle reach to required velocity VR which is equal

to the velocity of the vehicle when it utilizes the full

energy of the flywheel in accordance to the given

equation:

½Iῳ2 = ½mvR

2

Hence VR can be calculated.

• When the speed of the vehicle becomes equal to the

required velocity VR the clutch get disengaged from

the CVT and then the vehicle is solely run by the

engine only.

VIII. COST FEASIBILITY STUDY

Cost feasibility study is done to calculate the total cost of

KERS and the amount of money saved by using KERS

system. Cost study has been done into 3 stages-

1. Estimating the cost for the whole KERS system

assembly.

2. Estimating the Annual Saving in running cost of a

mainstream sedan in India.

Calculating the time of return of initial cost and the gain after

recovering initial cost of KERS.

Flywheel power and CO2 produced in an engine is also

studied.

Cost Estimation

Cost of buying and assembling of different parts of KERS

system is calculated. Components considered in cost

calculation are

1. Mechanical Components -Flywheel, linkages,

clutch, drive shaft, CVT/Torque Converter etc.

2. Electronic Components -Control system

components-Microprocessors, green boards,

Internal Circuitry, basic circuit

components(resistances, wires, capacitors, 3 pin

transformers)

3. Mounts and Casings -Steel mounts, flywheel

casing etc.

4. Bearings and Miscellaneous Components Cost-

Bearings, screws etc.

5. Assembly -Welding, Soldering, Logistics and

travel cost.

Table 4: Cost of Components [a,b,c]

S

No.

Component

group

Component Cost

in

rupees

Source

1 Mechanical Flywheel 4000 Instructables

Torque

converter 15075 Ebay

Clutch plate 3600 Amazon

Clutch cable 350 Local

Shaft 4400 Amazon

2 Electonics

Speed sensor 325 India Electricals

Microprocessor 500 Raspberry

3

Bearings Clutch release

bearings 450 Amazon

Shaft bearings 300 Local

4

Miscellaneous

and assembly Miscellaneous 15000 Logistics

Total cost 44000

Here the total cost of Flywheel Based KERS system comes

out to be Rs 44000.

Annual Saving In Running Cost

This data is collected by driving the cars in actual urban and

highway conditions in and around a typical Indian metro city.

This is calculated based on the assumption that the vehicle is

being driven for 1000km a month, 50% on highways and

50% on city roads. The cost of diesel is taken Rs65 and that

of petrol Rs 72 (the current price in Mumbai, Maharashtra)

Table 5: Petrol Cars Performance [d]

S

No.

Petrol cars City

mileage (kpl)

Highway

mileage (kpl)

Cost per

month (in Rs)

1 Tata Nano

15.1 20.6 5144

2 Maruti Alto

13.3 17.8 5177

3 Hyundai Eon

13.7 17.2 5211

4 Datson go

12.8 17.9 5442

5

Maruti

Wagon R 12.4 17 5161

6 Alto k10

14 17 5653

7 Hyundai i10

12 16.3 5460

9

Ford

Ecosport 1.0 11.8 17 5405

10

Maruti Swift

Petrol 12.6 17 4481

Table 6: Diesel Cars Performance [e]

S

No.

Diesel cars City

mileage (kpl)

Highway

mileage (kpl)

Cost per

month (in rs)

1 Hyundai Xcent 16.2 20.3 3561

2 Honda Amaze 15.2 20.8 3611

3 Chevrolet Beat 16 19.1 3703

4

Hyundai

Grand i10

15.4 19.6 3714

5 Tata Indigo 15.3 19.6 3724

6 Tata Indica 15.3 19.3 3757

7 Maruti Suzuki Swift Desire

14.6 19.8 3779

8 Nissan Micra 14.6 19.5 3812

9

Maruti Suzuki

Swift

14.6 19.5 3812

10 Ritz 14.6 19.3 3834

This additional data taken from UNEP concurs with the data

given by Maruti Suzuki India Limited.

Table 7: Average annual mileage of cars in 2 Cities [f]

City Cars (km)

Delhi 12804 +- 349

Vishakhapatnam 12199 +- 435




From the data obtained,

Average running cost per month of petrol cars = Rs 5268.9

Average running cost per month in diesel cars = Rs 3730.7

Net average cost of cars = Rs 8999.6/2 = Rs 4500

So, this is the average monthly cost of a car in India.

Now, fuel efficiency of Car with KERS= 25%

So, amount of cost saved per month = 25% of

4500 = Rs 1125

Therefore by using the Flywheel based KERS system we can

save upto Rs 1125 per month.

Annual saving in running cost = Rs (1125)x(12) = Rs

13500

Return Over The Years

In this phase, the return period and savings on running cost

are calculated for KERS system car.

Graphs have been plotted for Cost versus time and final

difference in costs is calculated.

From cost estimation,

Total cost of assembling the system = Rs 44000

Extra price paid by the customer for a Flywheel KERS car =

Rs 44000

From annual reduction in running cost,

Amount saved annually as calculated above = Rs 13500

Time taken to recover the initial cost = Rs 44000/13500 =

3.25 years In India, a petrol car can be run for only 15 years according

to the Law laid down. This is done keeping in regard the

pollution emissions.

Hence, money saved over 15 years due to addition of KERS

based system is given by

(Total Time-Return Period)x(Annual Saving)

(15-3.25)x13500= Rs 158625

Here we compare the cost of car with time for a car with and

without KERS system

Taking the example of Maruti Suzuki Swift Dzire.

Initial price for petrol car = Rs 5.4 lakh

Fuel cost per month = Rs 4481

Engine oil cost for average of 5000 km = Rs 4000

For 1 month, as the car travel 1000 km, so monthly cost of

engine oil = Rs 4000÷5

Now a plot of graph between the cost and time will have the

equation,

Taking y axis for coat and X axis for months, then

y(X) = 540000 + 4481x + 4000x/5

Now if we install a KERS system in the car, then

Initial fixed cost = Rs 5.4 lakh + 44 thousand

Cost of fuel per month = Rs 3360.75

Now, if we install a KERS system then expenses of gear box

oil will add in the expenses

Therefore, for 1 month expenses of engine oil = Rs 2×

4000÷5

Equation is,

y(X) = 540000 + 44000 + 3360.75x + 2×4000x/5

Plotting a graph for the 2 curves will give the breaking point ,

after which KERS car will give profit to the customer.

Table 8: Flywheel Power v/s CO2 Produced [g] Flybrid Power (kw)

IC Engine Power (kw)

Amount of co2 in Grams per km

15 120 130

45 80 110

60 70 95

80 50 75

100 30 50

Fig 13: Plot 5: Rupees v/s Months plotted on MATLAB

From the car it can be seen that, time taken for return of

initial cost is 39.27 months, that is 3 years 3 months.

Savings in 15 years is 1.576 lakhs.

Amount of Pollutants Reduced By Using Flywheel Based

KERS

Taking the example of MARUTI SUZUKI WAGONR car

Average distance covered by car in 1 month = 1000km

Average mileage of car = 14.7kpl

Amount of petrol used = 1000/14.7 = 69.027 litre

Now fuel saved by using the KERS system = 25%of 68.027 =

17 litre

Now, 1 litre of petrol produce CO2 = 2.3kg

Amount of CO2 in 17 litre of petrol = 2.3 X 17 = 39.1kg

So this is the amount of CO2 that is reduced by using a

flywheel in Wagon R.

CONCLUSION

A lot of areas were studied under this topic. The main

headings were:

1. A model for the system was made on DS Solidworks.

The model was a basic block model, and it helped in

getting an in depth and deep knowledge of the

construction and working of the Flywheel based KERS

system.

2. An energy study and various analyses were done for

the system. Mass of the flywheel was calculated to be

6kgs after graph plot and study using MATLAB.




Dimensioning was also done for the flywheel in this section.

An energy analysis was also done, for the different cases

arising while running this system. Fuel efficiency analysis

was done for a theoretical drive cycle and an actual drive

cycle for Pune City. Improvement in fuel efficiency due to

incorporation of the system came out to be 24.45%, a

substantial amount, advocating the addition of this system to

commercial vehicles in the Indian Subcontinent.

3. A control system was designed for the system for

monitoring the clutch actuation and governing the

whole system. A logic circuit diagram was made for

the control system and a driver program for the control

system was made on JAVA. Two programs were made,

one for the case of braking and the other for

accelerating after braking. The outputs are given and

the code has been attached as well.

4. Finally a cost study was done. In this the cost

feasibility of the system was confirmed. It was found

out that the system has an initial assembly cost of

Rs44000. This cost is gained back in 3.25 years by

saving on the running cost of fuel. Also, at the end of

15 years, the profit obtained was calculated to be

Rs157000, deeming this project a success.

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