Reversible air-conditioners and heat pumps using carbon dioxide (CO2, R744) as working fluid

Session 1

NEW REFRIGERANTS AND PERSPECTIVE ENERGY SAVING

Reversible Air-Conditioners and Heat Pumps

Using Carbon Dioxide (CO ₂ , R744) as Working Fluid

A.HAFNER & P.NEKSÅ

SINTEF Energy Research 7465 Trondheim

Norway

www.sintef.no

CONTENTS

 RAC

 Air Flow Reversing Units

 MAC

 Summary

 Conclusion

R744 RAC split-type unit

Water intercooler Outdoor

HX

Indoor HX Internal HX

Expansion valve

Oil cooler Oil separator

Low- pressure

receiver

Compressor

 R744 RAC Split-type unit

 Two stage compressor + external oil separator

 Internal Heat Exchanger with HP bypass

 Shown in AC-mode

R744 RAC split-type unit

 The results demonstrate that it is possible for a R744 RAC split-type unit to match the energy efficiency of the best R410A unit on the market in heating mode and in cooling mode in colder climates.

RAC System – Calculated SPF Heating Mode Cooling Mode Athens Oslo Athens Oslo

R744 prototype – measured data 4.3 2.7 4.4 6.7

R410A-unit – manufacturer data 4.0 2.6 5.3 6.7

Relative difference in SPF, R744 vs. R410A +7% +4% -17% 0%

 Further development and optimization of the R744 unit, e.g. by

utilizing microchannel heat exchangers, applying a compressor with a

higher isentropic efficiency and/or using an ejector or expander for

Reversible R744 systems

 Refrigerant reversing unit

 Several valves required

 Additional cost

 Heat exchanger mode changes

INDOOR

OUTDOOR

Alternative:

Reverse Air flow!

Set-up (heating)

INDOOR heating OUTDOOR

cooling

Animation

Picture of the R744 turn-table ECU

Results

1 2 3

-20 -10 0 10 20 30 40 50

Umgebungstemperatur [°C]

C OP [- ] & H ei z -/ K ühl lei s tun g [ k W

10 12 14 16 18 20 22 24 26 28 30

Innenr aum tem per at ur [ °C ]

COP Heizen COP Kühlen

Q Heizen Q Kühlen

Innenraumtemperatur

Ambient temperature

heating cooling

Indoor temperature

Indoor t em per at ur e [° C ]

Temperature bin / Climate / Location

0 500 1000 1500 2000 2500

< - 20 to -

15 to -

10

0 to -5 -5 t

o 0 0 t o 5 5 t o 1

0 o 1

5 o 2

0 o 2

5 o 3

0 o 3

5

35 -40

40 -45 >4 5

N um ber of annual hour s

Beijing Baghdad New Delhi

0 1 2 3 4 5 6

MW h/ a

D ie sel gener at or

Koh

lek raf tw er k rgi em

ix C hi na rgi em

ix Indi en

J ähr lic her E ner gi ebedar f [ M W h/ a] .

0 1 2 3 4 5 6

J ähr lic her äqui v . C O 2 A us s toß [m e tr i. to n / a ]

Peking Bagdad Neu Delhi

Office hours

(8 a.m. – 5 p.m.)

 3-3.2 MWh/a

 Dieselgenerator 2.3-2.5 m.ton/a

 Coal power p.

2.8-3 m.ton/a

 China / India

2.25 / 2.7 m.ton/a

Energy Demand & CO2 Emissions

Summary: Air reversing unit

 An air reversing, turn-table ECU was designed and experimentally investigated with promising

results.

 The refrigerant circuit can be unchanged, when directing the air through the designated heat

exchanger by rotating the entire refrigeration unit.

 The function of the heat exchanger does not change, i.e. the gascooler can be optimized for a low temperature approaches.

 No refrigerant charge issues, this can be handled

MAC Mobile Air Conditioning

 Misuse of GreenMACLCCP, when comparing Non-Natural Alternatives with R744 MACs

 Reduction of fuel consumption of R744 MACs

versus NNA’s (= energy saving potential), vehicle

measurements by leading TIER 1 and OEM’s

Phase II Simulation results for energy

Vehicle Mid – size Full Size

Drive cycle NEDC US FTP 75

Cycle duration

1180 sec. 2138

System Demand

Energy/ cycle [kJ] Energy/ cycle [kJ]

R 134a Base Base

R 152a -3% -7%

R 744*

*Optimized Refrigerant Controls

-11% -9%

Based on analysis of the accuracy and repeatability of the

SAE ARCRP II Results

SAE ARCRP II Results, European

Scenario

ARCRP II US Scenario

SAE ARCRP II Results -> LCCP

LCCP CO ₂ -Equivalent Emissions during Vehicle's Lifetime

0 2.000 4.000 6.000 8.000 10.000 12.000 14.000 16.000 18.000

P ho eni

x H ous

ton B os

ton C hi cago F ar go

WD C

Los A nge

les Mi

a mi M ont

real T or ont

o

V an couv

er

M e x ic o C ity ue

nos A ir es

io de J a nei

ro

C . A m e ri ca

C . A M . O

th e r

S . A M . O

th e r C ar ac a s

H e lsi n ki M os

cow S to ck hol

m O sl o

C openh agen

P rague W a rs a w

Lj ubl

jana

E . E U . O

th e r D ubl

in

A m st er dam V ienna

F ra nk fur

t

B rus sel

s A nk

ar a Lond

on D ebr

ec en

G enev a

B ra ti sl a va B uc

har es

t Pa

ri s Po

rt o M adr

id R o me

A th ens J er us

al em M . E . O

th e r T o ky o

K ag os hi m a

S ap por

o

B an gal

or e B om

bay N ew

D el hi S y dney

B ei jing S ha

nghai K w an

gj u T ehr

an T ai pe

i

ua la Lum

pur B an

gk ok A s ia O

ther

ohannes bur

g

CO 2 -E q u ival en t E m issi o n s ( kg )

Baseline - R-134a R744

Indirect Emissions Reduction AC ON

T o ta l F u e l C o n s u m p ti o n l /1 0 0 k m R 134 a F D C R 744 E V D C G ra ms CO 2 em issi o n p er km d ri v en

R 134 a E V D C

~ 35

~1.3

~ 27

~1.0

~ 19

~0.7

0ff 0ff

T o ta l F u e l C o n s u m p ti o n l /1 0 0 k m R 134 a F D C R 744 E V D C G ra ms CO 2 em issi o n p er km d ri v en

R 134 a E V D C

~ 35

~1.3 ~ 35

~1.3

~ 27

~1.0 ~ 27

~1.0

~ 19

~0.7 ~ 19

~0.7

0ff 0ff

Off line for 2008 average Fuel consumption according to 99 / 100 7 EG

Total l/100km: 5,8

CO ₂ -Emission: 140 g/km Values without A/C

R134a with EVDC

+ 0,1l/100km (off mode) R744 with EVDC

+ 0,05l/100km (off mode)

OEM-Result

Vehicle Test Results – Fuel Consumption

NEDC Fuel Consumption Test R134a vs. R744 VW Touran TDI 1,9l; T _ambient =20/28/35 ° C

Additional Fuel Consumption R134a Additional Fuel Cons. R744

T ambient

A ddi ti ona l Fue l C ons um pt ion l/ 1 0 0 k m

Fuel Consumption Test Results

OEM-Result

Small European Vehicle Fuel Consumption

1,5l gasoline engine T _amb = 35 ° C, SunLoad = 850W HVAC setting: Outside Air and Blower Position 6 of 8

F uel c ons um pt ion

General Conclusion

 Efficient R744 RAC split-type units are possible.

 Turn-table residential AC-units, applying

R744 as working fluid, are viable option for many global areas, where both heating and cooling is required during a year.

 R744 MAC systems are the most efficient, sustainable, non-flammable, environ-

mental safe and global solutions for

cooling and heating of vehicles in the future.

Thank you

for your attention!

Questions are welcome!!!

Please ask for a copy of the presentation

Contact:

[email protected]

Acknowledgement:

Many thanks for financial support of this effort from US-Army, and Modine for the ECU project.

Many thanks for the ‘ppt-slides’ support from OE for the MAC

chapter of this presentation.