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Improving
Car Climate Control
using SLS
– An industrial project –
M.Sc. ETH Mat. Sc. Marc Vetterli inspire AG, CH-9014 St. Gallen
SFF, Austin (TX), 12.08.2015
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Agenda
Introduction – Emission reduction
How – A) Design optimization
B) SLS materials
C) Real condition testing
What – Results
Conclusion – Achievements
Outlook
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Introduction – Emission reduction
Zacharof, N., Tietge, U., and Mock, P., ICCT, 2015
*New European Drive Cycle
Gra
ms C
O2 p
er
kilo
mete
r (n
orm
aliz
ed to
NE
DC
*) L
iters
per 1
00 k
ilom
ete
rs (g
aso
line e
qu
iva
len
t)
2000 2005 2010 2015 2020 2025
220
180
100
60
140
9
5
3
7
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-4
-2
0
2
4
6
8
10
12
14
0 50 100 150
ΔT [°C]
Driving Speed [km/h]
4
Introduction – Air conditioning in summer
NASA, Mercedes-Benz/Wieck Grossman, 2013
Broad air intake
Narrow air intake
Theoretical limit
GOAL
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Introduction – How to prevent the summer heating?
Hot air
(outside + hood)
Air pre-conditioning box:
«Enable a heat-exchange between
cool inner room air and outside hot air»
AC Car
Warm outflow
Cool air
IN flow
OUT flow
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Introduction – Heat exchange at the box wall
Convective Heat Transfer Convective Heat TransferHeat
Conduction
λ
dα1 α2
ΔT
Heat Transfer
Heat flux [W]
A Area of Wall [m2]
d Thickness of Wall [m]
ΔT Temperature Difference [K]
λ Heat Conductivity [W/mK]
U Overall Heat Transfer Coefficient [W/m2K]
α Convective Heat Transfer Coefficient [W/m2K]
Q.
Typical temperature profile
of heat transfer from a fluid
to another fluid through a
wall
Heat flux equation
Overall heat transfer coefficient
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Introduction – Improvement through SLS
Heat flux equation
Overall heat transfer coefficient
DESIGN FREEDOM
Area can be increased
TAILORED MATERIALS
Addition of fillers to enhance
thermal conductivity
SLS ROUGH SURFACES
Improving the convective heat
transfer coefficients by increased
roughness
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How – A) Design optimization
Step 1: Outer + inner box Step 2: Inner box 2X Area Step 3: Inner box 3X Area
Last step: - Box with inserts
- Conductive material where most needed
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How – A) Design optimization
Step 1: Outer + inner box Step 2: Inner box 2X Area Step 3: Inner box 3X Area
Chosen design: - Box with inserts
- Inserts can be made out of different materials
- Big dimension outer box out of polyamide on EOS P760
(525X334x337mm)
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How – B) SLS materials
GOAL of industrial partner: filled polypropylene with λ ≈ 0.35 [W/mK]
Developed powders
A1 – iCoPP, polypropylene copolymer, D50,vol 47.3 µm
A2 – iCoPP + with 20wt% surf. treated calcium carbonate (Omyafilm 753 – FL, Supplier: Omya)
A3 – iCoPP + with 20wt% talcum, D50,vol 15.6 µm (Luzenac 1445,Supplier: Imerys)
B – polypropylene reinforced by talcum, obtained by coextrusion, D50,vol 46.2 µm
Commercial powders
C – Microfol Sinterplast, PP reinforced by glass beads, dry blend, D50,vol 68.1 µm
D – Duraform HST, PA12 reinforced by mineral fibers, dry blend, D50,vol 60.5 µm
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How – B) Investigation methods
Characterization of powder properties:
FLOWABILITY - Revolution powder analyzer (backlit rotating cylinder)
- Information: avalanche angle, surface fractal indication on
powder flow homogeneity
THERMAL B. - Differential Scanning Calorimetry (DSC)
- Information: sintering window indication of process stability
Characterization of processed material properties:
HEAT CONDUCTIVITY - Modulated DSC (ASTM E1952-11)
- Information: effect of fillers on thermal conductivity
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What – Flowability & DSC
0
1
2
3
4
5
6
7
0
10
20
30
40
50
60
70
B A1 C D A2 A3
Surf
ace F
racta
l [-
]
Avala
nche A
ngle
[°]
Avalanche Angle
Surface Fractal
0
5
10
15
20
25
A3 A1 A2 C D B
(Tm
-Tc)o
nset [°
C] Sintering Window
A1 – iCoPP
A2 – iCoPP + CaCO3
A3 – iCoPP + talcum
B – talcum filled coextruded PP
C – Microfol Sinterplast
D – Duraform HST
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What – Thermal conductivity
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0.55
0.60
D A1 C A2 A3 B
Therm
al C
onductivity @
27°C
[W
/mK
]
λ @ 27°C
λ Industry PP
A1 – iCoPP
A2 – iCoPP + CaCO3
A3 – iCoPP + talcum
B – talcum filled coextruded PP
C – Microfol Sinterplast
D – Duraform HST
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What – Materials screening
Material B presents the best results in regard to all investigations:
Talcum-filled coextruded polypropylene
- Low avalanche angle and surface fractal good/homogeneous flowing properties
- High thermal conductivity enabled by talcum inside the particles
Material B Material A3
Same kind of filler (talcum) different behaviour!!!
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What – C) Real condition testing
Inserts:
- PA12
- A1
- B
Inner box: PA12 Under the hood.
In climatic chamber with sunny summer day
conditions in western Europe:
- World Light Duty Test Procedure cycle (WLTP)
- Temperature 30°C
- Relative humidity 65%
- Windshield irradiation 1000 W/m2
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What – Air temperature before AC
0
20
40
60
80
100
120
140
25
27
29
31
33
35
37
39
41
43
45
0 500 1000 1500 2000
Speed [k
m/h
] Tem
pera
ture
at P
art
itio
n W
all
[°C
]
Time [s]
PV1 PV2
Serie C-Class
PA12 A1
B
PV1 - Premium vehicle 1 PA12 Duraform inserts
PV2 - Premium vehicle 2 A1 - iCoPP inserts
Serie C-Class B – coextruded PP inserts
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What – Fuel consumption
15
20
25
30
35
40
45
50
25 27 29 31 33 35 37 39
Fuel C
onsum
ption [
gC
O2/k
m]
Air Temperature at Partition Wall [°C]
Serie C-Class 204
Premium Vehicle (PV1)
A1
B
PV 2
PA12
AC goes from 20%* to 10% of total energy consumption!
* Farrington, 2000
-51 %
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Conclusion – Achievements
- A simple solution to reduce the CO2 emission for cars in Europe of 10%
(or 46 Mtons/year)
- Diminish fuel consumption = increase driving range (electric cars!)
- The combination of
Thermodynamics
Additive manufacturing
Material optimization
Real condition testing
were successfully implemented to confirm this simple yet powerful idea!
- Do not forget to bring your fillers INSIDE your SLS particles
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Outlook – Does it work for heating as well?
The system works for cooling.
Does it work for heating as well?
Electric cars in winter: you either chose confort or driving range.
Would it be possible to have both?
This is the current investigation done by the industrial partner Weidplas
and the first results seem to be positive!
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Acknowledgments
A successful industry-driven project thanks to:
- Stefan Harke, Weidplas in Rapperswil and his team
- Christian Bach, EMPA in Dübendorf and his team
- Manfred Schmid, inspire in St.Gallen and his team
Thank you very much for your attention!
Do you have questions?