A new methodology for the experimental evaluation of organic friction reducers additives in high fuel economy engine oils. M.

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1 A new methodology for the experimental evaluation of organic friction reducers additives in high fuel economy engine oils M. Lattuada

2 Outline CO 2 emission scenario Engine oil: contribution to fuel economy Experimental procedure Laboratory test results Comparison between laboratory and engine tests results Conclusion 2

3 Leading driving force towards fuel economy FUEL ECONOMY lower CO 2 contribution WARMING! resources conservation CO 2 lower costs of car ownership 3

4 CO 2 emission trend in XX century 4

5 CO 2 reduction scenario in EU European Commission set a mandatory emission reduction target for new cars fleet of 130 g/km by 2015 Penalty payments for excess emissions are applied Supercredits for low CO 2 emission cars (less than 50 g/km) are applied A new target for 2021 has been set at 95 g/km (with introduction of a new world wide testing cycle), phased in from 2020 Phases 95% of manufacturer s new fleet must fulfill the limit by 2020 this percentage rises to 100% by 2021, jointly with supercredits reduction a further supercredits reduction is planned for 2022 supercredits will be cancelled by 2023 The 2021 target is fixed to reach a reduction in fuel consumption equal to approximately 4.1 l/100 km (for gasoline) or 3.6 l/100 km (for diesel) compared to 2015 target If the average CO 2 emissions of a manufacturer's fleet exceed its limit value, penalty payments for excess emissions will be applied 5

6 CO 2 reduction scenario in USA Corporate Average Fuel Economy (CAFE) standards are regulations aimed to improve the average fuel economy of cars and light trucks produced for sale in the United States Current CAFE rules consider an average of 35.5 m.p.g. New standard requires to meet annual mileage increases of 5% from 2017 through 2025 The 2025 final target is 54.5 m.p.g (4.3 liters/100km) for passenger cars 6

7 Lubricant contribution to fuel economy Only about 15% of the energy derived from fuel is used to generate vehicle movement on road and to drive accessories: the remaining energy is lost Need of strong improvement in terms of fuel economy by means of use of innovative technologies Lubricant plays an important role in limiting friction losses 7

8 Role of lubricant in friction reduction Friction reducers additives (FR) in engine oils contribute to improve energy efficiency by reducing friction between metal surfaces in contact FR operate mainly in the boundary region 8

9 Purpose of the study Set-up a new methodology for the laboratory evaluation of friction reducers additives in engine oil able to provide acceptable correlation with fuel economy engine test Selection of friction reducers additives Selection of a reference formulation Tribological test Investigate anti-friction behaviour of candidate oil on fresh and aged samples Laboratory test Reproduce ageing of lubricant by severe oxidation test Fuel economy engine test Measurement of fuel economy benefit of candidate oil in a standard engine test included in API specification 9

10 Selection of reference and candidate oils Reference oil: R Eni SAE 0W-20 oil, of API SN RC and ILSAC GF-5 performance level Candidate oils : A1 A2 B1 B2 C D1 D2 D3 Eni SAE 0W-20 oils containing 8 organic friction reducers of 4 different chemical classes at the same percentage 10

11 Tribological and laboratory tests EHL traction measurement system Tribological test developed by Imperial College of London Oxidation test Duration : 168 h Temperature: 160 C Air flow rate : 10 l/h Reflux condenser Fe Catalyst : 100 ppm Investigate friction behaviour of oil in all lubrication regimes by reproducing Stribeck Curve The area under each curve, also known as Stribeck Friction Coefficient (SFC), qualitatively represents the amount of energy loss due to friction Ageing of candidate oil in order to evaluate the retention of antifriction performances 11

12 Fuel economy engine test Sequence VI-D Fuel Economy Test Measurement of fuel consumption of candidate oil vs a standard reference oil 2 phases formed by 6 stages running at different operating conditions 16 hours of aging before starting phase 1 84 hours of aging before starting phase 2 Fuel Economy Improvement after phase 1 (FEI1) Fuel Economy Improvement after phase 2 (FEI2) The sum of both phases (FEI1+FEI2) is also calculated 12

13 Experimental methodology scheme SFC1 SFC1+SFC2 SFC2 EHL traction measurement test EHL traction measurement test COMPARISON COMPARISON Reference + 8 candidate oils COMPARISON Oxidation test Seq. VID Fuel economy FEI1 FEI2 FEI1+FEI2 13

14 Laboratory results Stribeck Calculation Friction of the Coefficient sum : for Fresh Aged oil : SFC2 SFC1 SFC1+SFC2 Boundary lubrication Mixed-film lubrication Hydrodinamic lubrication SFC are calculated in boundary-mixed regimes where FR s contribute is expected to be significative 14

15 Laboratory results: chemical class A All samples present a depletion of antifriction performance after ageing 15

16 Laboratory results: chemical class B B1:best performance after ageing within whole curve 16

17 Laboratory results: chemical class C C: best performance as fresh but a net degradation as aged 17

18 Laboratory results: chemical class D D1 and D2 performances are very high in both fresh and aged phases 18

19 Laboratory vs engine test on fresh oil Fresh D1 and D2 as the best, class B as the worst C has been slightly overestimated in lab test 19

20 Laboratory vs engine test on aged oil Aged D1, D2 and also B1 confirm promising laboratory evidences Ref has been slightly underestimated in lab test 20

21 Laboratory vs engine test: fresh + aged oil Fresh + Aged The whole correlation (fresh + aged phases) between lab and engine test is quite appreciable 21

22 Conclusion A laboratory methodology for the evaluation of friction reducers performances, on both fresh and aged oil, was set-up. An Eni 0W-20 oil, of API SN RC and ILSAC GF-5 performance level, was considered as reference formulation. Eight candidate oils with different organic friction reducers were selected and tested. The same oils were tested in the Sequence VID, fuel economy standard engine test for ILSAC GF-5 specification. Appreciable agreement between laboratory and engine test results emerged. The new methodology may be considered as a valid screening tool of friction reducers, giving useful indications on the fuel economy potential of engine oil without excessive spending in engine tests. 22

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