stirling machine as auxiliary power unit for range extender hybrid … · 2019-02-08 ·...
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