International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 8, August 2014)
Analysis of Effect of Physical Parameters on Energy Balance
for Energy Conservation for Vehicle in Motion
Shivraj Pawar1, Prof. N. N. Shinde2, Prof. M. M. Wagh3
1, 2, 3
Department of Energy Technology, Shivaji University, Kolhapur, India
In a vehicle several forces act on it and the net or
resultant force governs the motion according to the
Newton's second law. The propulsion unit of the vehicle
delivers the force necessary to move the vehicle forward.
This force of the propulsion unit helps the vehicle to
overcome the resisting forces due to gravity, air and tire
resistance. The acceleration of the vehicle depends on:
1. the power delivered by the propulsion unit
2. the road conditions
3. the aerodynamics of the vehicle
4. the composite mass of the vehicle
When the vehicle moves, it encounters a resistive force
that tries to retard its motion. The resistive forces are
1. Rolling resistance
2. Aerodynamic drag
3. Uphill resistance
Abstract— Fossil fuels will continue to play a dominant role
in the energy scenario in the next few decades. The number of
vehicles on road increased tremendously in last decades. The
light duty vehicles are increased faster than other category.
Thus it is necessary to conserve this energy in this
transportation sector. This paper reveals the analysis of the
effect of physical parameters of vehicle in motion for the
energy conservation. The effect of these parameters such as
mass of vehicle, air resistance, rolling resistance and braking
resistance is studied. The power ad energy balance is further
done and simulation is done through sankey diagram with ESankey software.
Keywords— energy balance, road resistance, rolling
resistance, air resistance, grade resistance
I. INTRODUCTION
In case of automobile vehicles energy balance can be
written on the basis of energy used per kg or litre of fuel
used. This energy is utilized to overcoming the forces
acting on the vehicle in the opposite direction of the
motion. The effort is made to write the energy balance
considering the fundamental parameters that take part in
forming the forces like drag, friction etc. while work is
being done by the vehicle. The energy is involved when it
is in motion
A. Rolling resistance:
Moment can be equivalently replaced by horizontal
force acting on the wheel centre in the direction opposite to
the movement of the wheel. This equivalent force is called
the rolling resistance and its magnitude is given by [1],
-------------------------------------- (2)
When a vehicle is moving up a gradient, the normal
force (P), in equation, is replaced by the component that is
perpendicular to the road surface. Hence, equation is
rewritten as,
II. FACTORS AFFECTING THE ENERGY BALANCE
Total fuel energy available is given by,
---------------------------------- (1)
--------------- (3)
Where,
In vehicle performance calculation, it is sufficient to
consider the rolling resistance coefficient as a linear
function of speed. For most common range of inflation
pressure, the following equation can be used for a
passenger car on a concrete road,
= rate of energy of power in kw
= net heating value in kJ/kg
m= mass flow rate of fuel in kg
The fundamentals of vehicle design involve the basic
principles of physics, specially the Newton's second law of
motion. According to Newton's second law the acceleration
of an object is proportional to the net force exerted on it.
Hence, an object accelerates when the net force acting on it
is not zero.
--------------- (4)
Where V is vehicle speed in km/h
268
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 8, August 2014)
B. Air resistance:
A vehicle travelling at a particular speed in air
encounters a force resisting its motion. This force is known
as aerodynamic drag. The main causes of aerodynamic drag
are:
1. Shape drag
2. Skin effect
The aerodynamic drag is expressed as [1]
-------------------------- (8)
Where
= rotational inertia constant
M = mass of the vehicle in kg
V = speed of the vehicle m/s
is Rotational Inertia factor, considering the equivalent
mass increase due to the angular moments of the rotating
components. The mass factor can be written as[4]
------------------------------- (5)
Where
= density of air in kg/m2
= vehicle frontal area in m2
V = vehicle speed m/s
The dynamic equations of the vehicle are used to
analyze the impact of drive cycle on the performance .The
dynamic equations of the vehicle give the force required to
move vehicle give the force required to move the vehicle
and this force is given by
= drag coefficient
C. Grade resistance:
When a vehicle goes up or down a slope its weight
produces a component of force that is always directed
downwards. This force component opposes the forward
motion, i.e. the grade climbing.
------------------ (9)
--------------------------- (6)
Where
w = total weight of vehicle in N
----------------- (10)
The power can be determined as
= inclination of the slope to the horizontal
----------------- (11)
D. Transmission system
In addition to the driving resistance occurring in steady
state motion, inertial forces also occur during acceleration
and braking. The total mass of the vehicle and the inertial
mass of those rotating parts of the drive accelerated or
braked are the factors influencing the resistance to
acceleration.
Where,
Therefore equation (11) can be converted as
=
}
-------------------------------- (12)
------------------------ (7)
The energy at given time at velocity V, is therefore
M = mass of vehicle in kg
Jrot = inertia of rotational components
V = vehicle speed in m/s
=
-------------------------------- (13)
= dynamic radius of the tyre
Rotational component is a function of the gear ratio. The
moment of inertia of the rotating drive elements of engine,
clutch, gearbox, drive shaft, etc., including all the road
wheels are reduced to the driving axle. The acceleration
resistance can be expressed as
Eq.13 is called the fundamental energy equation as it is
written in terms of fundamental design parameters like
mass and vehicle speed, area, road angle etc..
269
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 8, August 2014)
The factors like gravity, drag coefficient, friction factor,
density, rotational inertia etc are constant and derivatives of
dependent parameters. The energy required for the vehicle
to attain the velocity V1 from V2 is therefore given by the
following equation,
=
------------------------- (14)
=
------------------------- (15)
In practice the total energy generated by the fuel in
engine is used for above basic resistances plus auxiliary
consumptions like lighting, space conditioning, automation
equipments and devices. Each of utilization has its own
conversation efficiencies called losses. The energy
conservation can be achieved by improving efficiencies or
reducing the losses.
The energy balance at steady state, thus can be written as
under
Where,
Fig.1 Example energy flows for vehicle
Similarly for electric vehicles,
270
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 8, August 2014)
As these constants can be found out for different vehicle
types the availability of the power can be determined using
these equations as per the urban and highway conditions.
Efficiency dependence:
The efficiencies of various components from the energy
flows for a car are classified as
1. Engines efficiency
2. Accessories efficiency
3. Driveline Efficiency
Efficiency improvement opportunities:
1. Increase in efficiency can be achieved by reduction in
engine losses including friction losses by various means.
2. Accessories losses are reduced by providing separate
battery system for supplying electricity to accessories.
3. Reduction in rolling resistance:
It will lead to increase in fuel economy and a
proportional reduction in fuel consumption thus increasing
efficiency. This can be attained by using low resistance
tires.
4. Reduction in vehicle mass:
This may lead to increase in efficiency. This can be done
by usage of lightweight material for the vehicle body, tire
materials and other components.
5. Enhancement in aerodynamics of vehicle:
The reduction of aerodynamics resistance by better
shape and reduction of vehicle frontal area result in decline
in power loss due to air resistance hence results in increase
in efficiency.
Fig.2 Sankey diagram for overall energy flow for vehicle
III. CONCLUSION
The analysis of effect of physical parameters is done in
case of vehicle in motion by considering energy balance
and power balance. The energy conservation in vehicle has
been targeted to achieve, improve energy efficiencies by
analyzing base parameters such as mass of vehicle, friction
factor, moment of inertia etc. The sankey diagram obtained
by simulating each of the process parameters for urban and
highway road conditions as per FTP-75. It is interestingly
to note that the maximum power loss is in engine. The
motion of the vehicle concluded only through aerodynamic
design (air resistance), rolling resistance (friction factor)
and brake resistance which range 16-20%. Nowadays for
automobile vehicles energy conservation has been
increased for standby and accessories energy kept idle as
per their requirements. This concludes almost 60-65% of
losses are in fuel to utility energy consumption. It is
consciously derived that IC engines can be replaced by
suitable electric drive which does have maximum loss of
10% for its conversion from electric to utility consumption.
Fig.3 Sankey diagram for energy flow in driveline
In sankey diagram the size of the arrow represents the
percentage energy efficiencies in corresponding areas of
application like engine loss, standby and accessories power
consumption and driveline efficiency. The energy and
power balance are first time derived in terms of
dimensionless efficiency constants. This will help for
energy conservation and finding control over base
parameters as indicated below.
271
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 8, August 2014)
[12] S.M. Ferdous, Walid Bin Khaled, Benozir Ahmed, Sayedus Salehin,
Enaiyat Ghani Ovy. (2011). Electric Vehicle with Charging Facility
in Motion using Wind Energy. Sustainable transport World
Renewable energy Congress . 13 (8), p1-8.
[13] Santiangeli Adrianoa, Fiori Chiara, Zuccari Fabrizio, Dell’Era
Alessandro., Orecchini Fabio, D’Orazio Annalisa. (2013).
Experimental analysis of the auxiliaries consumption in the energy
balance of a pre-series plug-in hybrid-electric vehicle. Energy
Procedia ELSEVIER. 45 , p779-788.
[14] Max Ahman. (2001). Primary energy efficiency of alternative
powertrains in vehicles. Pergamon ELSEVIER . 26 , p983-989.
[15] A. Irimescu, L. Mihon And G. Pãdure (2011). Automotive
Transmission Efficiency measurement using a Chassis
dynamometer. International Journal of Automotive Technology. 12 ,
p555-559.
[16] Tires and Passenger vehicle fuel economy.(2006) Transportation
research board special report.p63-65.
[17] James D. Halderman (2012). Automotive Technology
Principles,Diagnosis and Service. 4th ed. New Jersey: PEARSON.
p1-1665.
[18] Eugene A. Avallone, Theodore Baumeister, Ali M. Sadegh (2012).
Marks' Standard Handbook for mechanical engineers. 11th ed. New
York: McGraw Hill. p11.1-11.128.
Thus there is wide scope for further theoretical and
experimental analysis in this area of energy conservation
by energy balance method.
REFERENCES
[1]
Thomas D. Gillespie (1992). Fundamentals of Vehicle Dynamics.
Warrendale, PA 15096-0001 USA: SAE International. p1-495.
[2] Bureau of Energy Efficiency. General Aspect of Energy
Management and Energy Audit. p1-23
[3] James Larminie, John Lowry (2003). Electric Vehicle Technology
Explained. Antony Rowe Ltd, Chippenham, Wiltshire: John Wiley
& Sons Ltd. p183-236.
[4] M. Ehsani, Modern Electric, Hybrid Electric and Fuel Cell Vehicles:
Fundamentals, Theory and Design, CRC Press, 2005
[5] Richard Stone and Jeffrey K. Ball (2004). Automotive Engineering
Fundamentals. Warrendale, PA 15096-0001 USA: SAE
International. P435-491.
[6] J.Y.Wong (2001). Theory of ground vehicles. 3rd ed. Newyork:
John Wiley & Song. p203-334.
[7] Robert Bosch (2002). Bosch Electronic Automotive Handbook. 1 st
Edition. p1-1301.
[8] Reza N. Jazar (2008). Vehicle Dynamics Theory and Application.
Riverdale, NY: Springer. p39-209.
[9] Jan Danko et.al. (2010). Energy analysis of hybrid power source
during vehicle in motion. Slovak University of technology, p1-6.
[10] Zdzislaw Juda. (2009). Range and acceleration analyze of an electric
driven city car with advanced energy storage. Journal of KONES
Powertrain and Transport. 16 (2), p1-8.
[11] G.Frydrychowicz-Jastrzębska, E. Perez Gomez. (2010).Computer
simulation of power balance of a solar vehicle depending on its
parameters and outside factors. Universidad de Politecnica de
Cartagena 30202 Cartagena, Spain. p1-6
Authors Profile
Mr. Shivraj Pralhad Pawar
B. E. Mechanical
M. Tech Research Student
Energy Technology
Department of Technology,
Shivaji University, Kolhapur.
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