In this rapidly developing world, the main threat that is being faced is on fossil fuel. As every year pass by, the amount of fuels used are going up the mark of the previous years. If this rate keeps increasing, the fossil fuels will be completely depleted to a state that these fossil fuels will only be known in names and due to the increased use of these fuels have led to the all kinds of pollution. In the recent study, it was proved that automotive fields are one with the greater consumption and polluting rate compared to other fields using fossil fuels. And, one of those pollution hazards is increase in carbon footprint, which is the total amount greenhouse gases produced. In order to face the upcoming threat, a new concept has been developed which would reduce the consumption of fossil fuels and pollution hazards. A concept of an electric car with minimum or zero emission and eco friendly features suiting to the nature protection is to be developed.
To develop, a concept on a family hatch back vehicle with low carbon emission which is powered by electricity and designed for an urban drive cycle with help of quality function deployment (QFD)
To do technical research in order to become aware of current developments in the market;
To prepare a specification for a low carbon vehicle;
To develop several concepts;
To select one concept using QFD;
To prepare a Gantt chart for the concept development phase of the project.
1.3 SPECIFICATIONS OF THE VEHICLE:
Table 1.3.1 is the Final specification of the LCV. Further report will explain how these specifications were finalised.
Minimum ground clearance
Max laden weight
Lithium ion, 1000 cycles
120 miles minimum under normal urban conditions
Aluminium honey comb
1.0 Conceptual Approach:
QFD for Electric Vehicle:
Table 1.1.1 is the QFD of the whole vehicle. The relation between Controllable parameters and Customers & Stake holders requirements has be rated accordingly, where 9-strongest, 3-moderate, 1-weak, and 0-no relation. This gives an idea on which controllable parameter we will have to work more.
Table 1.1.1 QFD of the Electric vehicle
The parameters Battery (342), Energy Storage Capacity (268), Drive Motor (231), Wear Resistance (239), Price (303) shows maximum absolute importance, hence, selection procedure will be carried on, while giving maximum priority to these parameters.
1.2 Fish Bone:
The Fish Bone diagram shows a manner in which over objectives will be achieved.
Diagram 1.2.1 Fish Bone Diagram
Gantt chart of Concept Phase:
Practically speaking, Concept phase may take 2 to 3 years to complete. Chart 1.2.1 is our basic Concept Phase Gantt Chart showing how a concept of a project is developed; if we were suppose to create a real prototype.
1.4 Gantt chart of the Group Time Plan:
Chart 1.4.1 shows time planning of the group to perform different tasks by group members.
Chart 1.4.1 Group time Plan Gantt Chart
Thus, from the Gantt chart now we know that which tasks are over lapping the other tasks( blue in colour ), and which tasks start at the end of particular tasks ( red in colour ).
Batteries are one of the most important things, when it comes to an electric vehicle, as they are only source of energy. Hence, selection of proper batteries plays an important role for the functioning of all the systems in an electric vehicle. This section will cover some ideas, which were used for selection of our batteries.
2.1 Selection Procedure:
Basic thing to start with was to look into the requirements, according to the market needs. Table 2.1.1 shows requirements of EV batteries depending on different characteristics and parameters, adopted by USABC (United States Advanced Battery Consortium).
Battery Requirements as per USABC:
Table 2.1.1 (Anderman, Fritz, & MacArthur, 2000)
In our case we will be considering requirements related to long term. Further selection procedure will be more or less based on these requirements.
2.2 Available Electric Vehicle Batteries:
A. Nickel Metal Hydride:
Nickel Metal Hydride batteries passed various bench tests and were best among other candidates for electric vehicle batteries. They were almost capable of giving a calendar life of about 10 years. But disadvantages of using Nickel Metal Hydride was that they are having very low specific energy 60 to 80Wh/kg and thus a lower range for the vehicle to run in single charge. For getting higher driving range the size of the batteries will have to be increased and eventually the weight also increases.
B. Lithium ion:
And where the Nickel Metal Hydride batteries were failing Lithium ion passed, hence they were with every good properties of Nickel Metal Hydride and some more advantages. Lithium ion became more suitable option to be used for electric vehicle batteries and as they have specific energy ranging up to 450Wh/kg and better specific power. Most of the present and upcoming electric vehicles are using Lithium ion technology.
C. Lithium Polymer:
Lithium polymer shows the potential of being cheaper than Lithium ion and Nickel Metal Hydrides batteries as cost of active materials is low in its case. Also having higher specific energy about 650Wh/kg. But, still the process of manufacturing these batteries is very complicated along with high cost electrolyte. Also the working temperatures of these batteries restrict them from being a better option (Delucchi & Lipman, 2001).
Hence, the most feasible option is the Lithium ion (Table 2.2.1).
Nickel Metal Hydride
Specific Energy (Wh/kg)
60 to 80
150 to 450
Up to 650
Specific Power (W/kg)
150 to 200
150 to 800
Cycles (100% DoD to 80% of initial capacity)
600 to 1000
200 to 600
Nominal Capacity (Ah)
100 to 180
50 to 120
Table 2.2.1 Characteristics Table (Anderman, Fritz, & MacArthur, 2000)
2.3 Selected Lithium Ion:
QFD chart for batteries:
Chart 2.3.1 Battery QFD
Our battery Requirements and QFD chart gives a clear idea that Lithium ion battery is better than Nickel metal Hydride and Lithium polymer. Also, from the QFD chart it is very much clear that, Battery Size (291), Product Life (156), Price (116), Durability (115), and Charging Speed (105), have maximum absolute importance and relative importance. Hence, for deciding the final specifications of the batteries these parameters will be given more importance as compared to others.
2.4 Trade Offs Among Different Lithium Ion Battery Technologies:
Lithium ion itself has many different types of variants or different battery technologies in it, hence, further approach is working on more specific constraints of the batteries.
Table 2.4.1 (Dinger & Martin, 2010)
Most important factor for EV batteries is the safety. Chemical reactions taking place inside the batteries, while they are working or because of overcharging results in high temperatures, which may result in fire. Table 2.4.1 shows, Lithium Nickel Cobalt Aluminium (NCA) has least safety characteristics, whereas Lithium Nickel Manganese Cobalt (NMC) and Lithium Manganese Spinel (LMO) have moderate safety characteristics and, Lithium Titanate (LTO) and Lithium Iron Phosphate (LFP) have highest safety characters.
Life span can be considered in two ways one number of times batteries being fully charged and discharge till it is degraded to 80% of its fully charged original capacity and second number of years battery can be used.
Performance in case of battery is basically how well the battery will perform in different climatic conditions.
Specific Energy is capacity for storing energy per kilogram of weight. Gasoline has almost 100 times more than that of the batteries. Hence, specific energy can also be deciding factor for size and weight of the batteries. Higher specific energy can result in low weight and smaller size of the batteries.
Specific Power is the amount of power delivered per kilogram of mass. Specific is less important as compared to specific energy in electric vehicles.
As for now, the lithium ion battery packs has cost estimates is between £700 to £850 per KWh, but with increase in technological development and competition among different manufacturers, the manufacturing costs of the batteries may decrease. The target shown by USABC is £250 per KWh by 2020, but somehow Nissan is already claiming of providing battery packs at same figures with Nissan Leaf. So cost factor is likely to down very soon.
Which is better?
LTO and LFP do have very less safety problems, but when it comes to specific energy they fall behind. And NCA is cost effective, with higher specific energy, specific power and life span, but lags very much behind in safety. LMO has all the factors average as compared to others and short life span. Therefore, considering the requirements (Table 2.1.1), Characteristics Table (Table 2.2.1), QFD (chart 2.3.1) and all the factors, NMC is the most suitable Lithium ion battery technology. They have moderate safety features, but this can be overcome by using proper battery casing, cooling system and temperature monitoring devices, in reasonable cost range (Anderman, Fritz, & MacArthur, 2000) (Dinger & Martin, 2010) (Delucchi & Lipman, 2001).
2.5 Battery Manufacturers:
Before defining our final battery specifications looking for Battery manufacturers and battery configurations these manufacturers have, is a good idea. Manufactures have their own R&D sectors, and they welcome the needs of the customer. Below are some manufacturers who can provide us with Lithium-ion batteries for our Electric Vehicle.
J & A
Automotive Energy Supply Corporation
GS Yuasa Corporation
(Momentum Technologies LLC, 1995-2010)
2.6 Battery Specifications:
Our selection procedure thus, leads us to battery specifications which will fulfil our requirements. Table 2.6.1 shows our approximate battery specifications. This may change in terms of size, weight and cost, or even chemical properties depending on the manufacturers.
3 to 6 hours and 30 mins for rapid charging
£250 to £300 per kWh / £7500 to £9000 per battery pack
2.7 High Voltage Electrical Distribution System:
Electrical Loads in an automobile can divided into two categories - propulsion and non-propulsion. Propulsion load mainly consists of motor and/or generator and Non-propulsion loads include heaters, lamps, power windows etc. Maximum power is required for the propulsion loads which can be up to 100KW. Table 2.7.1 gives an approximate idea for power distribution in our case.
Power Input (kW)
Table 2.7.1 (Automotive Handbook, 2007)
The electric vehicle has power buses at different voltages ranging from lower to higher values and can be as high as 300 volts. Hence, proper power management and distribution system will be adopted in order to meet the needs of our vehicle components (Fig 2.7.2).
Generic Automotive Power/Energy Management and Distribution system (Shen, Masrur, Garg, & Monroe, 2003)
3.0 MOTORS AND POWER ELECTRONICS
3.1 Working principle of motors (Leitman & Brant, 2009):
When electric potential is applied, the windings generate the magnetic fields which cause the armature to rotate and thereby, generate power. The efficiency of the electric motor ranges from 85 to 98%.
3.2 Present day EV's:
TYPE OF MOTOR
AC permanent magnet synchronous motor
AC permanent magnet synchronous motor
AC permanent magnet synchronous motor
3.3 Propulsion system design (Larminie & John, 2003):
Maximum percentage grade
Aerodynamic drag co-efficient
Rated velocity on a given slope
3.4 Advantages of electric motors over IC engines:
Full torque at low speeds
Instantaneous power rating is approximately 2 to 3 times the rated power of motor
Excellent acceleration with a nominally rated motor
3.5 Types of motors (Larminie & John, 2003):
Motors are basically categorized into DC motors and AC motors.
3.51 DC motors:
Extensively used till 1990's
Has 2 sets of windings- stator and rotor
The torque is maintained by commutator brushes
Winding in the rotor is called armature and winding in stator is called field winding
Ease of control due to linearity
Capability for independent torque and flux control
Established manufacturing technology
Brush wear that leads to high maintenance
Low maximum speed
EMI due to commutator action
Low power to weight ratio
3.52 AC motors:
Armature circuit is on stator which eliminates the need for commutator and brushes
Synchronous - permanent magnet type, electromagnet type
Asynchronous - squirrel cage, wound rotor.
3.53 Permanent magnet type AC motors (Hussain, 2003):
They use magnets to produce air-gap magnetic flux instead of field coils.
Permanent magnet synchronous motors
Sinusoidal brushless DC motor
Trapezoidal or square wave motor
Provide a loss-free excitation in a compact way without complications of connections to the external stationary electric circuits
High power to weight ratio
High torque to inertia ratio
Excellent field weakening characteristics
Sensitive to temperature and load variations
3.54 Switched reluctance motors:
Doubly salient, singly excited reluctance motor with independent phase windings on the stator. Generally stator and rotor are magnetic steel laminations with rotor having no magnets or windings.
Simple and low cost machine construction
Wider constant power region
Bidirectional currents are not necessary, hence lesser number of power switches
Most of the losses appear in stator, which is easier to cool
High torque to inertia ratio
Torque-speed characteristics of the motor can be tailored as per requirement
Maximum permissible rotor temperature is high
Torque ripple and accoustic noise observed
Special converter and higher terminal connections required, hence not economical.
Torque to inertia ratio
Power to weight ratio
Price and maintenance cost
Î£ motor definition criterion
PM Synchronous motors
Î£ Parameters importance
0 - Not Preferred
3 - Poor
6 - Good
9 - Excellent
Hence it is better to incorporate PM synchronous motor or Switched reluctance motor in the electric car. After referring the above chart, its evident that PM synchronous AC motors are more suitable for moderate power requirements.
3.6 Power electronics in electric car (Hussain, 2003):
Electric motor drive converts stiff DC battery voltage to DC/ AC voltage with a RMS value and frequency that can be adjusted according to the control command.
Electric motor drive: Its typically is a combination of,
POWER ELECTRONIC CONVERTER + ASSOCIATED CONTROLLER
Power electronic controller: It is made up of solid state devices and handles flow of bulk power from the source to motor input terminals. It functions as ON/OFF switch to convert fixed supply voltage into variable voltage and variable frequency supply. They constitute of high-power and rapid response semiconductor devices.
Drive controller: It accepts command and feedback signals, processes it and generates gate switching signals for the power devices of the converter. It is made up of microprocessors and digital signal processors.
Figure : Block diagram of motor drive (Hussain, 2003)
Figure : DC-DC and DC-AC converters (Hussain, 2003)
3.61 Power electronic switches (Hussain, 2003):
BJT: Bi-polar junction transistors have better power ratings and excellent conductivity, but their drive circuit is complicated as they are current-driven.
MOSFET: Metal oxide semiconductor field effect transistor has simpler drive circuits and higher switching frequency, but their maximum available power ratings are lesser than BJT.
IGBT: Insulated gate bipolar transistor incorporates the advantaged of both BJT and MOSFET and are extensively used in modern day electric cars.
SCR: Silicon controlled thyristor have higher power ratings but requires a commutation circuit to switch them Off.
GTO: Gate turn-off SCR is a type of improvised SCR that can be switched off through a gate signal but their current consumption is typically 4 to 5 times the current required to switch them on.
MCT: MOS controlled thyristor combines the conduction characteristics of SCR and gating characteristics of MOSFET.
Diodes: They are two-terminal semiconductor devices and are used in conjunction with other controller devices. Their function is to block the reverse voltage flow and provide current path for inductive circuits.
3.7 A typical PM synchronous motor drive structure: (Hussain, 2003)
LIGHT WEIGHT STRUCTURES
4.1 INTRODUCTION TO STEELS
Sheet steel has remained the main material used for the construction of the body of a motor vehicle ever since mass production began earlier this century. Steel is relatively is cheap and can be economically formed to make parts with complicated shapes and has a high degree of rigidity, higher crash impact resistance and high elastic modulus. In the recent days, aluminium alloys have been extensively used for automobile components. The alloy has aluminium as base metal with traces of chromium, copper, iron, magnesium, manganese, silicon, titanium and zinc added to it. The proportions are differed according to the requirement of the end product and these alloys are almost replacing the steels in automobile sector. The essential factors behind this development have been the needs to reduce fuel consumption by reducing the weight of car and increased passenger safety (C.Dasarathy, 2010).
4.2 STEEL USED IN AUTOMOBILEÂÂÂ
As forged sections
As wire products
Hot rolled sheet t=1.5-7.00mm for body panels, closures,biw parts , sumps, fuel tanks , exhaust parts.
Crank shafts, connecting roads, axle parts, tie rods, valves.
For tyre reinforcement, springs , etc
For body, under body structural parts cold rolled -annealed -coated sheet=0.5-1.5mm
Aluminium is a metallic element, and its structure is similar to most other metals. It is malleable and ductile due to its polycrystalline structure. Aluminium is made of grains which interlock when the metal is cooled from molten. Each grain comprises of rows of atoms in ordered lattice arrangement, giving each grain an isotropic structure. Although the different grains are somewhat randomly arranged with in grain boundaries forming during the cooling process, the atoms within each crystal are normally aligned which makes the metal isotropic, like the individual grains. (Sam Davyson)
4.4 ALLOYING ADDITIONS FOR AUTOMOBILES
A small quantity of other elements added to aluminium in order to modify its basic properties. They are chromium, copper, iron, magnesium, manganese, silicon, titanium and zinc. These elements can be grouped into those with high solid solubility and those with low solid solubility.
4.5 PROPERTIES SPECIAL STEEL & ALUMINIUM ALLOYS
Heavier in weight with density of 7.85gm/cu.cm
Lighter in weight with density approx 1/3rdof that of steel. The density is about 2.72gm/cu.cm
Elastic modulus &bending specific stiffness
Elastic modulus of 210 Gpa longitudinal i.e. young's modulus which 3times more than that of aluminium. But bending stiffness is more than aluminium which provide more advantage for using in structures like front crash rails, b-pillars etc.
Elastic modulus of 70 Gpa. It has got shock absorption tendency so mostly used in automobile bumpers. It is used as outer skin surface in automobile it has greater specific bending stiffness for flat products.
Less thermal conductive than aluminium
3 times more thermal conductive than steel making it a choice in heat exchange applications.
Fatigue performance of steel is more than twice that of aluminium. Steels such as DUAL PHASE 600 AND TRIP 600 have endurance limits of 307 Mpa &336 Mpa respectively.
Structural aluminium grade of 5XXX series does not reach an endurance limit and continue degrading at higher cycles. Aluminium grade 5052-0 reaches 124 Mpa at 500 million cycles.
High formable range than aluminium making it suitable for vehicles styling and overall manufacturing robustness.
Formability is approximately 2/3rdof that of steel.
Nowhere near aluminium electrical conductor in power transmission.
High electrical conductivity for use as lines, transformers, bus bars etc.
Lesser reflective than aluminium.
Excellent reflector of radiant energy throughout entire range of wave lengths. Light reflecting capacity of over 80% making it suitable for light fixtures. In roofing , it reflect high amount of sun heat promoting cool interior atmosphere in summer.
Steels in general are magnetic. Austenitic stainless steels are non magnetic with AISI 304LN, 316LN some steel grades possessing very low magnetic permeability for use in structures close to sensitive electronic devices or medical equipment.
It is highly nonmagnetic and hence finding extensive use for electrical shielding such as bus bar, magnetic compass housings, computer disc manufacturing ,parabolic antennas etc.
High temperature resistance
Steels like T-11,T-22, martens tic stainless and austenitic stainless steel like AISI 310 are highly creep resistant with ability to resist deformation at high temperatures. Steels containing 8% aluminium.
Poor high temperature resistance
Low temperature toughness
Steels in general posses poor low temperature toughness.
Shows excellent toughness at low temperatures finding use in refrigeration.
Much higher than aluminium and its alloys.
Tensile strength of pure aluminium is very much lower but, the property can be improved by additions of Mn, Si, Cu &Mg and through tempering aluminium alloys has a tensile strength of 295 Mpa.
Very much higher than aluminium alloy
The mechanical properties are improved by additions of Mn, Si, Cu, &Mg and through tempering.
Shows good machinability in high sulphur steels and lead bearing steels.
Show excellent machinability
Harder than aluminium denting tendency less than aluminium
Lower hardness than steel.
Ability to attenuate air bone noise due to its huge mass over aluminium.
Inability to attenuate air borne noise compared to steel
Strain rate sensitivity
High strain rate sensitive displaying positive strain rate performance.
Not strain rate sensitive and has poor crash worthiness.
Corrosion &weather resistance
Austenitic stainless steel like AISI 304 &316 shows excellent corrosion resistance. Shows good gal vanic, pit and inter-granular corrosion resistance
Good corrosion resistance and the rate of corrosion is 1/25thof high resistance steels. It is excellent weather resistant.
Austenitic stainless steels 300 series are known for their non -toxic nature. Tin plate steels are used for preserving food, edible oils etc.
Highly non-toxic. Aluminium foil wrapping d foil of 0.007mm thickness is completely impermeable.
Excellent for austenitic stainless steels with low maintenance costs.
Attractive appearance with low maintenance costs. Finds use in cladding, hardware etc.
TABLE 4.4.1 (B.V.R Raja)
There is lot of skill and technology behind the development and use of honeycomb chassis. The typical part of aluminium skin in honeycomb panel is good in certain areas. Honeycomb chassis can take great significant loads on edge. But this can't take much load in 90 degrees to that great extent. The design panel is resistant to all weather conditions although they are not designed to expose to atmosphere. The bonding between the honeycomb and the aluminium skin is very strong to water resistant but the bonding is not water proof. So when designing the chassis we must take effective steps to prevent to keep road water and salts out off the panels and joints to avoid corrosion and damage to chassis. More technical skill is required while fixing the panels. To the specific needs, you needed to attach the panels without affecting their physical property. We can't rivet or screw the panels together for perfect bonding. (Cliffbeer, 2007)
4.7 RACK AND PINION SYSTEM
In rack and pinion type, the gear on the steering column's end is similar to the pinion gear in the differential cut on an angle, and meshed with a steel bar (the rack) toothed on one side.
The rack is mounted parallel to the front axle and as the steering wheel turns, it operates directly on the tie rods without the use of a pitman arm, idler or intermediate (or relay) rod.
Adding a power assist to this type of steering is quite simple. The power piston is actually part of the rack, and the rack housing acts as the cylinder.
The control valve is located in the pinion housing. Rotation of the steering shaft and pinion turns the valve to direct hydraulic pressure to either end of the rack piston.
4.8 MACPHERSON STRUT FRONT SUSPENSION
The most widely used front suspension system in cars of European origin .The system comprises of a strut-type spring and shock absorber combo, which pivots on
a ball joint on the single, lower arm The strut itself is the load-bearing member in
this assembly, with the spring and shock absorber merely performing their duty as
oppose to actually holding the car up.
4.9 MULTI-LINK REAR SUSPENSION
This is the latest incarnation of the double wishbone system. The basic principle of it is the same, but instead of solid upper and lower wishbones, each 'arm' of the wishbone is a separate item. These are joined at the top and bottom of the spindle thus forming the wishbone shape. The super-weird thing about this is that as the spindle turns for steering, it alters the geometry of the suspension by torquing all four suspension arms. (Chris Longhurst, 1994-2004)
Aerodynamics encompass all the air flows that pass over, around, and through a vehicle they can be subdivided in those affecting performance/ fuel consumption , comfort ,cooling, vehicle dynamics, directional stability and perceptibility safety. (Automotive Handbook, 2007)
4.11 PRODUCT SPECIFICATION
Exterior panels, Bumpers
5.0 Energy Recovery and System
In a Low Carbon Vehicle, the energy lost or used, if recovered, could make the system more efficient. In order to recover the energy, two types of system are applied.
Solar Energy Panels
Regenerative Braking System
5.1 Solar Energy Panels (Darrell D. Ebbing, 2007) (SPI, 2005-2010) (Inventables, 2007)
Solar energy is the mostly available energy in the world. Taking this into knowledge, we introduce solar panels which convert solar energy into electric energy and are stored in the battery. There are two kind of solar panels used:-
Transparent and flexible solar panels
Plate type solar panels
The Semi transparent and flexible solar panels will be placed on each windows of the vehicle. So that the both the side of solar panel can be utilized accordingly and with the help of the green house effect, it helps in charging the battery from both the sides.
The Plate type solar panels will be placed on the roof of the vehicle and for the utilization of maximum solar energy
All the charges obtained from the solar panel will be stored in the battery using a control unit.
20W (Plate type solar panels)
10-14W (Semi transparent and flexible solar panels)
6-8 hrs (45% - 60%)
Maximum Power Voltage
Maximum Power Current
Open Circuit Voltage
Short Circuit Current
Table 5.1.1 Specification of the solar panels used. (navitron, 2004)
5.2 Regenerative Braking System (Boxwell, 2010 ) (Brain, 1998)
Regenerative braking system is an alternative way used to produce electrical energy from kinetic energy produced through braking. This energy is produced by the reverse rotation of the motor used in the vehicle. As vehicle go down the hill or into stopping point by braking, the electronic circuit or controller would make the motor rotate backward with the help of the tires and in this case, the motor which rotates the wheel would act as a generator to produce the electricity. This charge produced will be stored in the battery using a control unit. By this system, the energy lost would be recovered and stored, hence increasing the efficiency of the vehicle
(Automotive components and parts, 2008)
6.0 Parasitic Losses (Vehicle Technologies Program, 2009)
Parasitic loss is mainly known as the loss of the energy in the system. For electric cars, the parasitic loss is mainly due to the wind resistance and drag, braking and rolling resistance. It even includes the friction and wears in the vehicle, thermal (heat) loads, operation of auxiliary loads (air conditioning, heaters, refrigeration, etc.). (Inventables, 2007)This parasitic loss can immensely affect the efficiency of the vehicle.
Average power output
Side marker lamps
Low beam (dipped beam)
License - plate lamp, tail lamps
Indicator lamp, instruments
Heated rear window
Interior heating, fan
Electrical radiator ventilator
Turn signal lamps
Rear fog warning lamp
Installed electrical load requirements
Average electrical load requirements
Table 6.1 showing the consumption of components of an Electric vehicle
(Automotive Handbook, 2007)
Hence the parasitic losses occurred in the electrical components =
Hence there is an approximate parasitic loss of 5kW and more in this system.
7.0 HVAC (Heating, Ventilating and Air Conditioning)
HVAC (Heating, Ventilating and Air Conditioning) is a technology that deals with the indoor or automotive environment control with the principles of Thermodynamics, Fluid Mechanics and Heat transfer. Heating, Ventilating and Air Conditioning are closely interrelated in order to provide a thermal comfort in the indoors. Since it is used to control the quality of air it is also referred to as Climate control. HVAC is not only important in the design of medium to large industrial and office buildings and in marine environments but also in automobiles such as cars and trucks where safe andÂ healthyÂ conditions are regulated with temperature and humidity. Since, HVAC systems account for so much electric energy use, the efficiency of the system has to be improved through proper design, installation and scheduled maintenance.
HAVAC Systems perform conditioning the air in the following ways
Removing and adding heat.
Adding and removing moisture.
Volume of airflow.
Velocity of airflow.
Removing Impurities in air.
Fig 7.1 Ventilation System. (National Research Council Canada)
Providing an acceptable level of occupancy comfort
Maintenance of good air quality
Minimum energy requirements
Proper air flow, heating and cooling.
7.1 HVAC TYPES
The move to battery powered electric cars poses several challenges when it comes to climate control inside the vehicle. The hugely inefficient internal combustion engine's coolant system can easily be tapped for cabin heating are now gone while powering a 3 - 5 kw air conditioning compressor in an EV consumes only 200 wh/mile atÂ highway speeds. There are different types of HVACs used in Electric Vehicles.
THERMOELECTRIC DEVICES FOR AIR CONDITIONING
The thermoelectric HVAC will be optimised to provide the occupant comfort while reducing fuel consumption and greenhouse gas emissions. To maximize energy efficiency, the thermoelectric HVAC system will use a distributed heating or cooling design that targets individual occupants and reduces temperature conditioning to unoccupied passenger seating.
Tetrafluoroethane (R-134a) refrigerant gas is the most common working fluid in vehicular air conditioners since 1995.
R-134a has 1300 times greater greenhouse gas impact than CO2.
Car air conditioners leak 10 to 70 g/year.
Thermoelectric HVAC systems significantly reduce man's contribution to greenhouse gases while improving fuel economy.
7-8 billion gallons/year of fuel use for automotive A/C.
Approximately 6% of our national duty fuel use (ELECTRIC VEHICLE NEWS, 2009).
CLIMATE CONTROLLED SEATS (CCS)
This HVAC technology heats and cools surrounding structures such as the headliner, windows, flooring, and seat backs. These systems consume between 3.5-5 KW. To reduce this load, heating or cooling can be plumbed directly into the seats. These seats are called Climate Controlled Seats (CCS).
Since the seat has direct contact with the occupant it has much higher thermal conductivity compared to air which is a poor conductor. With direct contact cooling or heating load per person could be reduced to less than 700 Watts compared to 5,000 W to heat/cool the entire cabin (Fairbanks, THERMOELECTRIC DEVELOPMENTS FOR VEHICULAR APPLICATION, 2006).
Fig. 7.1.1 Climate Control Seats. (Fairbanks, 2006)
Fig 7.1.2 HVAC System in Electric Car. (ELECTRIC VEHICLE NEWS, 2009)
This plan presents scenarios for increased use of alternate fuels and vehicle technology efficiency improvements in order to reduce power consumption and greenhouse gas emissions. This system will demonstrate a minimum of 33% improvement in the energy consumed by a vehicle air conditioning system.
ZT (figure of merit) ~ 1; COP ~ 0.9-1.0; Distributed HVAC System; P ~ 2 kW; Power Off Alternator
Decreases ~ 0.8 mpg/vehicle (0.8/27.5 ~ 0.029) low Alternator Efficiency
ZT ~ 2; COP ~ 2; Distributed HVAC System; P ~ 1 KW; Power Off Alternator
Increases ~ 1.1 mpg/vehicle (1.1/27.5 ~ 0.04)
Either ZT Case; Power From Thermoelectric Generator Converting Engine Exhaust Heat to Electricity
Increases ~ 3 mpg/vehicle (3/27.5 ~ 0.11) (Fairbanks, THERMOELECTRIC DEVELOPMENTS FOR VEHICULAR APPLICATION, 2006)
PELTIER EFFECT THERMOELECTRIC
Peltier modules can be used to generate electricity, to provide air conditioning or they can be used to provide heating. In fact, Peltier modules make it possible to build versatile heating and cooling devices for applications that require an energy efficiency solution.
Peltier modules are thermoelectric (TE) devices that can be used to provide cooling or to generate electricity, depending on the application. The modules work according to the Peltier/Seebeck effect, which provides cooling by passing a current across two dissimilar materials, that's on opposite sides of the device. The current flow causes one side of the device to become hot and the other to become very cold.
A Peltier air conditioning solution can be built by configuring the Peltier modules to accept a current, which will cool one side of the module and heat the other. In this configuration, Peltier modules are often referred to as TEC or thermoelectric coolers. The hot side of the Peltier module will require a heat sink and a cooling fan to prevent overheating. The cool side of the Peltier module can then provide cooling by causing the ac fan to blow air across them. The same modules can also provide heating by changing the direction of the current flow. This will cause the hot side to become cold and the cold side to become hot, which makes Peltier modules an all round heating and air conditioning solution (Fairbanks, CAR and Vehicle Technologies Energy Efficiency and Renewable Energy US Department of Energy Washington, D.C).
7.2 AUXILIARY POWER UNIT
An Auxiliary Power Unit (APU) is used in the motor and electric vehicles in-order to provide energy for the vehicle other than starting up of engines. It is used for operating the power windows and Cabin light even before starting up of engine. The traditional APU is powered by fuel, which is less efficient and causes more pollution than the emerging battery powered APU's. Fuel cell APU is a typical type which uses fuel cell as a source of energy but involves no combustion and so is clean and efficient.
AUXILIARY POWER UNIT IN ELECTRIC VEHICLES
A battery electric vehicle has a relatively small fuel cell auxiliary power unit (APU) to recharge the battery pack during driving. The attraction of this configuration is the use of a relatively small battery pack (to allow 65 - 110 km of ZEV range) while increasing vehicle range and functionality to be equivalent to conventional vehicles (400 - 650km). Another key attraction is that a majority of km could be efficiently refueled from the grid allowing low or zero CO2 power generating technology to be deployed in private transportation without the enormous cost and inefficiency of the H2 infrastructure (Zizelman, 2000).
FUNCTIONS OF APU
APU in a car is responsible for and provides power to the
Air conditioning compressor
SOLID OXIDE FUEL CELL APU
The combination of Solid Oxide Fuel Cell (SOFC) APU and advanced Lithium Ion battery systems appears to make the fuel cell range extender EV an attractive system in terms of efficiency, weight and cost. The addition of the APU on the vehicle enhances the value of the vehicle to the electric grid by allowing the vehicle to operate as a back-up generator for the building next to which it is parked.
Delphi has been doing R&D on fuel reforming and fuel cells since 1990. The SOFC program began in 1999 with a customer-linked program to develop a 3-5 kW APU product for luxury passenger cars running on gasoline. The SOFC APU is a practical first step for introduction of fuel cells in transportation. But its linkage to luxury functions (like electric air conditioning) instead of propulsion and its use of conventional fuels, instead of direct H2, may make it seem like a timid first step. However a variety of future integration strategies for combined cycle SOFC/ICE, SOFC hybrid vehicles and the SOFC/Li-Ion range extender EV offer a wide spectrum of future "green" applications. In addition, SOFC is capable of burning H2 or other renewable fuels very efficiently. The SOFC system will inherently have extremely low emissions. No NOx will be formed in the reforming process and the post-combustor will operate at temperatures where no NOx and hydrocarbons are formed. But, the SOFC was assumed to achieve a 40% efficiency level for the generation of electricity ((Delphi), 2002).
8.0 Final Selection & Comments
Table 8.1.1 DFMEA
Design Failure Mode Effect Analysis is a systematic analysis of potential failure modes aimed at preventing those failures. It is an intended preventive action process carried out before implementing new or changes in products or processes. Table 8.1.1 shows Design Failure Mode Effect Analysis of our concept.
8.2 Risk Assessment:
Who is at risk?
Existing control measures
Battery explosion during crash and acid spillage
Passengers and people in the vicinity
Fire extinguisher in car, insulation
Remote alarm, acid spillage solidifier
Light weight structure. Aluminium alloy body
Fibre reinforced parts, impact bars, proximity sensors
HVAC working fluid spillage
Fluid flow &circuit breaker
Less noise during motion
Pedestrians and cyclists
Electric shocks due to short circuits
Electric insulation, shock preventer modules
8.3 Work Packages:
Batteries, High Voltage Electrical Distribution Systems
Drive Motors, Power Electronics
Manjunath T. R
Lightweight Structures, Vehicle Dynamics
Auxiliary Power Units, HVAC and System Cooling, Aerodynamic Performance
Energy Recovery and Storage, Parasitic Losses
Table 8.3 showing the distribution of work among the group
8.4 Project Plan Cost Report:
Overview of the project plan Cost report is shown in Table 8.41
Energy Recovery System
HVAC and Auxiliary Power Unit
Testing of Components
Table 8.41 Cost Report (Hamster Internet, Inc., 2011) (Resciniti, Peshkess, & Leonard, 2003) (Cost Variance Stoplights, 2010)
Chart 8.4.2 Pie Chart of Baseline Cost
Deliverables are the report, data or even products which are to be delivered. This is divided in two parts Internal Deliverable and External Deliverables. Internal Deliverables are things which are to be delivered within the people working on the project and external deliverables are those which the people working in the project deliver to the higher authorities or users i.e. outside of the project working environment. Table 8.5.1 and Table 8.5.2 show Internal and External deliverables related to our project.
Project and Development Planning Details
This includes Individual Section Time plan, Group Time Plan, QFD of the Project.
Status of the project
This includes report how a particular component was selected and/or implemented
Required Specifications of the vehicle
This includes the final specifications
Whole Project Report
Report on in what manner the project will be carried out.
Cost Report of the project
Project Requirement Details
Requirements details includes Machinery and/or Labour, Space required
Final Concept and/or Prototypes
Working prototype or Final concept
(Neville Turbit, 2011)
8.6 SWOT Analysis:
Better performance and lesser emissions
Futuristic design with lesser cabin noise and vibrations
High standards of safety
High specific power and specific energy batteries incorporated
Solar energy panels
Robust and eco-friendly
Overhauling and replacement are costlier
Charging points are inadequate at the moment
Use of paramagnets
Better marketing strategies
Cost of materials and components
Relaxation of laws
Higher subsidies and discounts
Rapid change in consumer expectations
Carbon footprint standards
Table 8.6.1 SWOT
Complete Study of the Project tells about the feasibility of the project, which are strengths, Weaknesses, Opportunities and Threats. Table 8.6.1 gives use details on feasibility of our concept.
Use of selection tools like Quality Function Deployment (QFD) helped in the concept development, and planning phase, including Fish Bone diagram, Concept Phase Gantt chart, and Gantt chart of Group Time Plan helped us in getting the final specifications of the concept vehicle. And hence, the concept of the vehicle is developed with carbon reduction technologies such as lithium ion batteries, and energy recovery methods which use of solar energy and regenerative braking system. SWOT analysis shows the strength, weakness, opportunities and threats of the concept and hence, making the scope of research and development much broader. Thus, we have a never ending chain of concept development and planning, to develop more economic and eco-friendly vehicles.