© inspire icams 1

Improving

Car Climate Control

using SLS

– An industrial project –

M.Sc. ETH Mat. Sc. Marc Vetterli inspire AG, CH-9014 St. Gallen

(vetterli@inspire.ethz.ch)

SFF, Austin (TX), 12.08.2015

© inspire icams 2

Agenda

Introduction – Emission reduction

How – A) Design optimization

B) SLS materials

C) Real condition testing

What – Results

Conclusion – Achievements

Outlook

© inspire icams 3

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

© inspire icams

-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

© inspire icams 5

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

© inspire icams 6

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

© inspire icams 7

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

© inspire icams 8

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

© inspire icams 9

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)

© inspire icams 10

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

© inspire icams 11

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

© inspire icams 12

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

© inspire icams 13

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

© inspire icams 14

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!!!

© inspire icams 15

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

© inspire icams 16

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

© inspire icams 17

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 %

© inspire icams 18

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

© inspire icams 19

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!

© inspire icams 20

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?