stirling machine as auxiliary power unit for range...
TRANSCRIPT
Stirling machine as auxiliary power unit for range
extender hybrid electric vehicles
Sylvie BEGOT, Steve DJETEL,
François LANZETTA– Femto st
Wissam BOU NADER – Groupe PSA
30/01/2019
Context and short term solutions
2
Problematic arises for post 2025 due to more stringent
reglementation regarding CO2 emissions
95g CO2/km
80g CO2/km
59g CO2/km
130g CO2/km
-37,5%
Powertrain & EMSEnergetic demands
ICE efficiency
aerodynamic
Rolling
resistancce
weight
Thermal
energetic needs
Auxiliaries
consumption
CO2 emission
≈
fuel consumption
CAFE = Corporate Average Fuel Economy / ICE=Internal Combustion engine / EMS = Energy Management Strategy
Internal Combustion Engine (ICE) powertrains main problematics
3
ICE multi-fuel compatibility
!Confort thermal energetic needs
Stirling
Gas-Turbine
Combined cycle
Split cycle
Solid combution E-fuel Hydrogen Bio-fuel
ICE Max efficiency
On the other hand… ongoing development of Battery Electric Vehicles (BEV)
4
Tesla
Renault Zoe
Citroën C0Benefit of Zero Vehicle Emission
(Tank to wheel emissions !!!)
5
AC
DC
Battery
Vehicle Controller
Driver performance request
APU Controller
SOC
Brake
Hydraulic brake
command
Traction/brake
recovery command
Wheel
>100kW.h
(500km)
(≈600kg)
• Large battery capacities for long autonomy range: Additional weight
However, BEVs present many drawbacks
Ele
ctri
c M
oto
r
• Thermal confort such as heating is not free compared to thermal based powertrains
• CO2 emission (well to wheel analysis) depends on the electricity production
• Geopolitical problematic for European automotive manufacturers
• Cost for the customer
BEV = Battery Electric Vehicle
6
Po
wer
trai
n a
nd
ener
gy
cost
(€
)
(15
.00
0km
/ye
ar/
10
yea
rs)
Tax
Other Energy
Electrical Energy
Engine / APU
Battery
E-motor
Reductor
ICE FCVBEVREX
SHEV
AC
DC
Battery
Vehicle Controller
APU Controller
Ele
ctri
c M
oto
r
Brake
Hydraulic brake
command
Traction/brake
recovery command
Wheel
≈10kW.h
(50km)
(≈150kg)
Ele
ctri
c G
ener
ato
r
Energy
Converter
Auxiliary Power Unit (APU)
BEV = Battery Electric Vehicle, FCV = Fuel Cell Vehicle, REX = Range Extender Vehicle,
SHEV = Series Hybrid Electric Vehicle, ZEV = Zero Emission Vehilce
SOC
Different energy converters with
different thermodynamic
configurations can be envisaged
Driver performance request
Range Extender powertrain seems to be a comprimise
>100kW.h
(500km)
(≈600kg)
• ZEV mode compared to ICE
• Low emission compared to ICE
• Cost compared to BEV and FCV
• Vehicle weight compared to BEV
• Fun to drive (such as BEV)
State of the art – Energy converters for automotive application
7
TA
TEG
PEM Fuel CellICE StirlingRankine
EricssonECGT
Mature technology for
automotive applications
Mature technology for non-
automotive applicationsNon-mature technology
Split Cycle
Gas Turbine
Internal Combustion Electro ChemicalExternal Combustion
CCGT = Combined cycle Gas Turbine
TA = Thermoacoustic
TEG = Thermoelectric Generator
ECGT=External Combustion Gas-Turbine
PEM = Proton Exchange Membrane
SOFC = Solid Oxide Fuel Cell
SOFCCCGT
Conventional Non Conventional
8
Early development of Stirling machine for automotive applications
Ford Torino Chevrolet Celebrity Opel Kadet
Automotive intrinstic benefits: Multi-fuel capability, good thermal efficiency, high
torque at low speed, silent operation, low vibration.
Many reasons hindered their deployments: Leakage, controllability, Investment
costs, and particularly the simplicity and price of the ICE at that time
9
Today with CO2 and emissions topics, Stirling for automotive applications gain interest
• Development of Series Hybrid Electric Vehicles (SHEV) :
o efficiently operation under all driving cycle
o quasi-stable operating state: reduce control complexity
• External combustion machine - Emission reduction through:
o Choice of fuel and continuous combustion
• Development of magnetic coupling systems:
o Complete sealing to avoid working fluid leakages
• Material advancement to reach higher temperature and pressure:
o Higher thermodynamic cycle efficiency and higher power density
10
AC
DC
AC
DC
Battery
Driver performance request
APU Controller
Ele
ctri
c
Gen
erat
or
Ele
ctri
c
Mo
tor
SOC
Brake
Hydraulic brake
command
AP
U O
N/O
FF
Traction/brake
recovery command
Wheel
Auxiliary Power Unit (APU)
Stirling
machine
Vehicle Criteria: fuel consumption
Requirements: Acceleration, Max speed, gradability
Constraints: Weight, Size, Frontal surface
Target of this work
Cabine
heatingAuxiliariesAC
WLTC cycle
Vehicle Controller
0
20
40
60
80
100
120
140
0
1000
2000
3000
4000
Vel
oci
ty (
km
/h)
Ener
get
ic n
eeds
Po
wer
(W)
Time (s)
Cogeneration machine for
automotive applications
11
Stirling cycle - Theory
Ideal Stirling Cycle
• 2 isothermal transformations
• Expansion 3-4
• Compression 1-2
• 2 isochoric transfromations
• Heating 2-3
• Cooling 4-1
Robert Stirling (1816) Hot air engine
Stirling engines
• External heat supply
• Closed cycle
• Regenerative engine
P
V
2
3
4
1
QH
2 QL
1
3 4
QR
QR
TH
TL
T
S
QR
P
V
2
3
4
1
Mechanical configuration : Beta
• One cylinder with 2 pistons
• Work piston : compression and
expansion
• Displacer piston : no work done,
moves the gas from the expansion
space to the compression space
Beta
Configuration
Cycle moteur Cycle frigorifique
Proto Femto 300 W
Designed prototype characteristics
Engine characteristics
Beta type Single cylinder
Working gas Nitrogen
Pressure 60 x 105 Pa
Power 12 kW
Generator 3 phase
Power piston diameter 10-1 m
Compression swept
volume
4.5 x 10-4 m3
Hot temperature 937 K
Cold temperature 337 K
Efficiency (target) 39 %
Frequency 35 Hz
PV Diagram from isothermal
analysis (Schmidt)
First tests :
• engine is driven by an electric drive
asynchronous engine
Inverter
• Reduced pressure 15 bar instead of 60
bar
• Reversed cycle : heat pump or
refrigerating cycle
Designed prototype characteristics
1
2
3
4
5
6
1: hot exchanger, 2: cold exchanger,
3: gas burner, 4: torquemeter,
5: electrical engine,
6: power electronics converter.
Results: pressure, torque, rotational speed for a few cycles
Results: as a refrigerating machine
-30°C dans le volume de détente
Vehicle model including an APU with ICE or Stirling engine
Vehicle specifications
Vehicle mass (+ driver) 1210 kg
Wheel friction coefficient 0.0106
Air density 1.205 kg/m3
Wheel radius 0.307 m
Auxiliaries consumption 750 W
Battery max. power 78 kW
Battery capacity [5, 10, 20] kWh
Battery mass[188, 259, 356]
kg
Battery state of charge [0.4, 0.6, 0.8, 1]
Stirling system 12 kW
Stirling efficiency 39 %
ICE power 97 kW
ICE max. efficiency 36 %
Vehicle specifications
Generator max. power 12 kW
Generator max.
efficiency95 %
Motor max. power 80 kW
Motor max. efficiency 93 %
Transmission ratio 5.4
Transmission efficiency 97 %
Fuel heating value 42.5 MJ/kg
Energy converters operation
• for both Stirling and ICE on plug-In SHEVs
powertrains
• three repeated WLTP
• 10kWh battery capacity
• Stirling engine operates at a lower power
and more continuously than ICE
Model results
Model results
Battery and fuel energy trade-off
for the plug-in configuration on one to
five-repeated WLTP, under the three
investigated battery capacities.
Powertrain efficiency of the
plug-in configuration, on one to
five-repeated WLTP, under the
three investigated battery
capacities.a
Fuel consumption results between
Stirling-system and ICE of the plug-in
on one to five-repeated WLTP, under
the three investigated battery
capacities.
• Alternative automobile powertrains are needed
• Series Hybrid Vehicles including a Stirling engine as APU is a good candidate
• Powertrain efficiencies and fuel consumption present good performances when
compared to a conventional ICE APU
• A 10 kW Stirling engine prototype has been developed and is currently under tests
Conclusion