1. Institute for Governance & Sustainable Development (IGSD)
Efficient & Affordable Secondary Loop Mobile Air Conditioners (SL-MACs)
Presented by
Dr. Stephen O. Andersen
Dr. Nancy J. Sherman
Institute for Governance & Sustainable Development (IGSD)

2. Breaking News! Next-Generation MAC from China
China auto makers, component suppliers, and universities collaborating on GWP <150 MAC refrigerants
Heat pump performance for electric vehicles (EVs); 480 EV companies and counting
SL-MAC at the forefront: Chinese experts highlight SL-MAC to enable affordable, low-GWP flammable refrigerants with “excellent performance” like HC-290
“Promising alternative refrigerant market in China”
Junye Shi, Jiangping Chen, and Dandong Wang Recent Advances on MAC Alternative Refrigerants in China. Presented at SAE International Thermal Management Systems Symposium, San Diego California, October 8 to 11, 2018.
GWP <150 refrigerants in affordable SL-MACs
Heat pump performance for electric vehicles (EVs); 480 EV companies and counting
China has validated adequate cooling and heating performance in HC-290 (propane) SL-MACs and is further investigating safety mitigation

3. GWP<150 Refrigerants Under Consideration in China
Advantages
Concerns
Solution(s)
HFO-1234yf
Near drop-in for current MAC system
Performance decay, high cost refrigerant
IHX, inner condenser compensation, price drops when patents expire
R744 (CO2)
Good heating performance
Poor cooling performance, expensive components
IHX, ejector compensation, cooperation with domestic suppliers
R290 (Propane)
Excellent performance, low cost refrigerant
Safety (highly flammable)
Secondary loop system, safety evaluation
HFC-152a
Mildly flammable
Secondary loop system, following SAE standards
Notes:
HC-290 and HFC-152a require secondary-loop designs (SL-MAC) or active safety systems (detect and safely discharge) to safely exclude flammable refrigerant from the passenger compartment
SAE Standards are under development for HFC-152a
HFO-1234yf and HFC-152a have easy and accurate leak testing; HFC-290 has difficult leak testing; CO2 has nearly impossible leak testing (how to detect small CO2 leaks in 400+ ppm CO2 air?)
Safety of CO2 systems requires discipline in not fabricating or substituting parts unable to safely contain the very high operating pressure
Only HFO-1234yf has trifluoroacetic (TFA) atmospheric by-products; HFC-152a, HFC-290, and R-744 do not form TFA

4. Breaking News! Next-Generation MAC from EU
EU auto maker, component suppliers, and universities collaborating under the EC “OPTEMUS Partnership” on a holistic approach to reduce energy consumption for electric vehicles by thermal management
Like China, the system architecture is SL-MAC and the refrigerant candidates CO2, HC-290, HFC-152a, and HFO-1234yf (all with are GWP <150)
Partners include: Bax & Willems Consulting Venturing, Centro Ricerche FIAT, Continental, Denso Thermal Systems, ESI Group, The Fraunhofer Gesellschaft, IFP Energies Nouvelles, Institut für Kraftfahrzeuge - RWTH Aachen University, Mondragon Goi Eskola Politeknikoa S.Coop, Scuola Superiore Sant’Anna - The BioRobotics Institute, Sistemi Sospensioni, Università degli Studi di Salerno, and The Virtual Vehicle Research Center
Hünemörder, W. and T. Györög Compact Coolant based Heat Pump Unit for Electric Vehicles. DENSO Automotive Deutschland. Presented at SAE International Thermal Management Systems Symposium, San Diego California, October 8 to 11.

5. Breaking News! Success in SL-MAC Demonstration
Redesigned SL-MACs have:
Comparable cooling capacity and cool down
Lower refrigerant charge and leakage
Higher energy efficiency
The combined SL-MAC manufacturing and ownership costs are less than status quo systems
HFC-152a SL-MACS are free from intellectual property restrictions and patents

6. CCAC SL-MAC Demonstration
UNEP CCAC
TATA Motors
MAHLE
IGSD
TATA Aria
baseline direct expansion (DX) dual A/C system
Apply SL-MAC system with improved power train control logic to reduce short-lived climate pollutants (SLCPs) and maximize energy efficiency advantage
TATA Aria 2.2L Dicor is selected vehicle with front and rear A/C system
Financial support by UNEP, a project of the Climate and Clean Air Coalition to Reduce Short- Lived Climate Pollutants (CCAC)
Advisors: California Air Resources Board (CARB), Chemours, Chrysler, Fiat, General Motors, Jaguar Land Rover, Neutronics Refrigerant Analysis, HF Consultancy, Natural Resources Defense Council (NRDC), Mobile Air Conditioning Society Worldwide (MACS), SAE International, Sun Test, TERRE Policy Centre, National Renewable Energy Laboratory (NREL), University of Maryland, and Valeo.

7. Aria SL-MAC in TATA Motors Pune Environment Test Facility

8. Summary of Accomplishments To Date
Target / Parameter
Baseline
Target
SL-MAC R-152a Results
(SL-MAC R-1234yf results pending)
Refrigerant (GWP)
R-134a (1300)
R-152a (138)
HFO-1234yf (<1)
GWP target met
Charge quantity
800 grams (±20 grams)
40% reduction
46% reduction
430 grams
Average Cabin Temperature at 25th min in 350C 40%RH Solar Load 1000W/m2
21.80 C
210 C±1
23.80 C
Needs normal development
Average Cabin Temperature at 25th min in 450C 40%RH Solar Load 1200W/m2
28.90 C
280 C±1
31.50 C
Compressor Power 2400 engine revolutions/minute
5.5 kW
5~8% reduction
9.6% reduction
5.0kW
Rise in Grill temp – City cycle tests
≤ 40 C
≤ 20 C
< 2.00 C
Fuel Economy (FE) - Indian Drive Cycle (ARAI) with AC ON (No Engine IDLE STOP/START strategy used in test)
12.55Kmpl
~3% Improvement
1.9% to 2.6% mix of city and highway condition
FE will slightly be reduced to get back same capacity (same cabin temp)
Engine IDLE STOP/START strategy will increase FE
Test Method (compressor power):
·         Compressor power consumption test is done at a vehicle level on a chassis dynamometer.
·         During the test, AC blowers are at maximum speed
·         Radiator fans are running at high speed (with external power supply).
Calculation (compressor power):
·         Compressor power consumption is a calculated value based on the difference in rear wheel traction power on the chassis dyno (difference between AC OFF to AC ON condition).
·         Pump power consumption is not included while calculating compressor power consumption (coolant pump power has been subtracted in the calculation)
Lower value of compressor power with R152 SL-MAC system can be explained due to lower density of the refrigerant (lower by ~52%) resulting in lower refrigerant mass flow rate in SL-MAC system

9. SL-MAC Manufacturing & Ownership Cost for India (in US Dollars): 2 Cooling Points
Direct Expansion (DX)-MAC
Secondary Loop (SL)-MAC
Refrigerant
charge 
tonnes CO2-eq (initial charge)
HFC-134a
800 g
1.04
HFO-1234yf
750 g
<0.01
HFC-152a
430 g
<0.1
530 g
Added manufacture cost
Baseline
$731
$362
$763
Cost each service estimated frequency
cost over 10 years:
$574
Every 3-5 yrs.
$114-$171
$1335
$266-$400
$546
Every 6-10 yrs.
$54
$1097
$103
Annual fuel savings
Based on 2.6% savings
tonnes CO2 over 10 years9
Not applicable
up to 39 litres8
$39 at $1/litre9
1 tonne
$39 at $1/litre
Additional SL MAC components are more affordable than HFO-1234yf refrigerant.
Significant manufacturer savings by choosing HFC-152a SL over DX HFO-1234yf
Slight manufacturer cost savings possible by applying HFO-1234yf in SL MAC instead of DX MAC
Based on manufacturer refrigerant price of $80 USD per KG of HFO 1234yf
SL MACs save consumers money too
Less leaky systems = fewer service needs
Fuel savings could also be significant
Notes:
Includes added cost of refrigerant plus components (IHX)
Includes added cost of SL MAC components and slight refrigerant savings due to lower charge
Included added cost of SL MAC components and increased refrigerant cost
Equals $50 labor cost plus cost of ½ charge of refrigerant at $16.90 / kg HFC-134a
Equals $50 labor cost plus cost of ½ charge of refrigerant at $222 / kg HFO-1234yf
Equals $50 labor cost plus cost of ½ charge of refrigerant at $16.90 / kg HFC-152a
Assumes km/year, 2.6% improvement over 12km per litre for SL MAC; Diesel price of 68 rupees ($1 USD) per litre
Assumes kg CO2 per litre diesel
Assumptions:
Refrigerant charge size (2 cooling points):
DX HFC-134a: 800 g
DX HFO-1234yf: 750 g (~93.5% of HFC-134a charge)
SL HFO-1234yf: 480 g
SL HFC-152a: 450 g (assumes lower charge than SL 1234yf needed due to refrigerant properties)
Refrigerant prices:
HFC-134a manufacturer price: $6 per kg (various industry sources)
HFC-134a service price: $16.90 per kg (source: O'Reilly Auto Parts, based on 30 pounds at $230)
HFC-152a manufacturer price: same as HFC-134a
HFC-152a service price: same as HFC-134a
HFO-1234yf manufacturer price: $80 / kg (source: Honeywell)
HFO-1234yf service price: $222 / kg (based on 4.5 kg at $1000)
Exchange rate: 1 USD = 68 Rupees
1 litre diesel in India = 68 Rupees
1 litre diesel = kg CO2 emissions

10. SL-MAC System Architecture Details
Vehicle Build
“Extra” content for development
Reservoir bypass valve
Flexibility of flow control
2 pumps
Control for front vs. rear flow is in development
19mm coolant hose
Boundary conditions:
Carryover compressor
Carryover condenser
Only TXV change R-152a to R-1234yf
Internal heat exchanger (IHX) not included
TML Controller
Application notes:
Time to comfort in SL-MAC system is demonstrated to be equivalent to direct expansion (DX) systems despite the need to cool the intermediate coolant
Added components slightly increase vehicle weight and fuel use, but SL advantages like cold storage expected to result in overall fuel economy improvement
Evaluate benefits exclusive to SL-MAC separate for those available to all systems
Unique to SL MACs:
Regenerative cooling, powered cooling controlled for least fuel use, cold storage, low-cost system with multiple (3+) cooling points
Both SL or DX MACs
Compressor preferentially engaged on deceleration, water flow to heater controlled by valve in hot weather, reduced Series Reheat, IHX

11. Significantly Reduced Refrigerant Leakage = Less Frequent Service
J2727
MAHLE Refrigerant Emissions Test Results - Aria System
J2763
Dynamic Test: Secondary loop results in 59% reduction in direct emissions (from 18.9 to 7.7 grams per year)
18.9 grams per year – 7.7 grams per year = a reduction of 11.2 grams per year
11.2 grams per year reduced / 18.9 grams per year baseline = , or 59% reduction
Static Test: Secondary loop results in 58% reduction in direct emissions (from 20.4 grams to 8.5 grams)
20.4 grams per year baseline – 8.5 grams per year SL MAC = a reduction of 11.9 grams/year
11.9 grams per year reduced / 20.4 grams per year baseline = , or 58% reduction
J2727
1 lip on compressor shaft seal: Secondary loop results in 37% reduction in direct emissions (from 25.7 to 16.1 grams per year)
25.7 grams per year – 16.1 grams per year = a reduction of 9.6 grams per year
9.6 grams per year reduced / grams per year baseline = , or 37% reduction
2 lips on compressor shaft seal: Secondary loop results in 48% reduction in direct emissions (from 21.8 to 12.1 grams per year)
21.8 grams per year baseline – 12.1 grams per year SL MAC = a reduction of 9.7 grams/year
9.7 grams per year reduced / 20.4 grams per year baseline = , or 48% reduction
Direct Emissions (Leakage) Cut in Half
% reduction in leakage
Higher reliability
Lower emissions
Less frequent service

12. Aria SL-MAC Test Plan in India: Next StepsSN
Test
Dec ‘17 – May ‘18
June ‘18
July ‘18
Aug. ‘18
Sept. ‘18
Oct. ‘18
Nov ’18
Dec ’18
HFC-152a System 1
Climatic Chamber & Fuel Efficiency Tests 2
Road Tests
HFO-1234yf System
Sept- Oct 2018
Road Tests Oct-Nov 2018
We are here
Final report 12

13. Questions?

14. Contact Information
Stephen O. Andersen
Nancy J. Sherman

15. The Montreal Protocol Protects Stratospheric Ozone; The 2016 Kigali Amendment Will Protect Climate
The Montreal Protocol has slowed and reversed the accumulation of ozone depleting substances (ODSs) in the stratosphere, as measured by effective stratospheric chlorine amounts.
Mitigation from F-gas cuts since 1974 = size of CO2 warming today
MP agreed to cut HFCs in 2016
Kigali Amendment will avoid 80 Gt CO2-e by 2050, up to 0.5C warming by 2100
Phase-down, not phase-out, will allow low-GWP HFCs with superior life-cycle climate performance to continue such as SL-MAC with R152a
MAC has long legacy of continual improvement for comfort and environment
Stephen A Montzka, NOAA/ESRL, 2006

16. All Parties Will Phase Down HFC-134a in MACs
In India, about 25% of total HFC use is MACs and about 20% of motor vehicle fuel powers MACs*
INDIA
India MAC fuel use source is TERI presentation by Sridhar Chidambaram, TERI Associate Fellow on India Policy Workshop on the Status of MAC replacement Technologies presented in New Delhi, India, 7-8 June 2010; it presented findings from an NREL study conducted with the support of TERI and UNEP DTIE with funding by US Environmental Protection Agency. See presentation given slide 14 out of 16: “NREL studies of fuel use of MAC in a vehicle.” The chart shows that in India 19.4% of Fuel is used for MAC in India. The explanation given is “Reason being high temperature and humidity, high cooling hours, smaller cars and road congestion.”
National Cooling Action Plan (NCAP) currently under development.
MAC & low GWP refrigerants to be covered.
CHINA
In May 2014, the State Council of China announced they would strengthen management of HFC emissions and accelerate the destruction and replacement of HFCs as part of the action plan to implement the energy conservation and emission reduction targets of the 12th 5-year plan.
-IGSD HFC Primer
With 24% of global MAC sales in 2015, China remains the largest vehicle market that still permits the indefinite use of HFC-134a.”
-ICCT 2016 report
2016 ICCT study found that a transition to low-GWP refrigerants could reduce fleet-wide GHG emissions of mobile refrigerants by more than 95% compared with an HFC-134a baseline. This reduction applies to operation, service, and end-of-life scrappage.
Cumulative emissions of up to about 1.5 billion metric tons (tonnes) of CO2 equivalent (CO2e) can be avoided through 2050.
Complete phaseout of HFC-134a is achievable by 2035–2040, which would require all new vehicles to stop using HFC-134a between 2020 and 2024.
The costs of transition are generally favorable relative to other available CO2 reduction technologies for motor vehicles. The cost-effectiveness for HFO‑1234yf declines from about 484 yuan per tonne (¥/mt) to about 312 ¥/mt by 2050, while that for CO2 declines from about ¥832 to about 436 ¥/mt over the same period. For HFC-152a, the cost-effectiveness declines from ¥241/mt to ¥179/mt by 2050.
Elsewhere in the world:
“The CCAC is targeting HFCs. Many CCAC have exiting HFC policies. 6 are developing national level inventories of HFCs and identifying policies and measures to avoid growth of high GWP HFCs including Bangladesh, Chile, Colombia, Ghana, Indonesia, Nigeria.”
*Source: U.S. National Renewable Energy Laboratory (NREL-US) and The Energy and Resources Institute (TERI-India)

17. TATA Aria SL-MAC System Bench Testing
Component Level Tests
Evaporator
Condenser
Chiller-Cooler Combination
System Bench Test
Q vs. COP
Per GreenMAC LCCP criteria, CRP-150
Aria SL-MAC Bench Test – MAHLE Lockport

18. Combined Effectiveness for given Cooler/Chiller
Energy and Capacity Considerations: Direct Expansion (DX) vs. Secondary Loop (SL)
P-h Diagram (SI Units)
80 kph, 38 C x 40%, Outside Air
100
1,000
10,000
150
250
350
450
550
650
Enthalpy [kJ/kg]
Absolute pressure [kPa A]
R152a SL
R134a
R152a
1,DX
1,SL
Summary: R-152a is a very good MAC refrigerant and component selection must be matched to it and the SL
Combined Effectiveness for given Cooler/Chiller
Cx = Air or Coolant heat capacity, respectively
Ref.: ‘Compact Heat Exchangers’, Kays and London, 3rd Edition

19. CWT Performance HFC-152a vs. HFC-134a
Transient AC Performance Test: Severe Ambient Condition
45 degrees C x 40%, 1200 W/m2 Max blower, max cool, recirc, chest mode
Tata Aria ITR and Cabin Temperature
Hot Soak + Cooldown
R152a (o) vs. R134a (-)
Driving temps within ~1 deg. C
At end of Idle temps within ~2 deg. C

20. CWT Performance SL-MAC AC-Off Comfort
Boundary Conditions:
Production A/C compressor
Production condenser & fan
Cold Storage:
35C Ambient
Comfort > 2 minutes after compressor off
NA comfort limit

21. R-152a to Replace HFC-134a in MACs in A5 Parties?
SNAP / F-Gas Option
GWP
(AR5)
Cooling Efficiency in High Ambient Temperatures
TFA
Toxicity/
Flammable
Application Patent/Price
HFO-1234yf
< 1
Good
Yes
ASHRAE A2L*
Yes/High
Carbon Dioxide - CO2
= 1
High Ambient No
No/Low
HFC-152a
= 138
Better
ASHRAE A2**
*ASHRAE Standard 34 A2L: lowest toxicity, lower flammability with burning velocity <10 cm/s
**ASHRAE Standard 34 A2: lowest toxicity, lower flammability with burning velocity =10 cm/s or higher
R-152a satisfies US EPA SNAP & EU F-Gas Directive (GWP<150)
More affordable than HFO-1234yf which is covered by application patent and more costly (bulk cost increased by 10~12 times)
Lower pressure, higher efficiency in high ambient temperature than CO2 (R-744)
Expected to remain available due to low GWP and life-cycle climate performance
No TFA