Engines and Fuels. Prof. David Kittelson TE Murphy Engine Research Laboratory Department of Mechanical Engineering University of Minnesota

Engines and Fuels Prof. David Kittelson TE Murphy Engine Research Laboratory Department of Mechanical Engineering University of Minnesota 2016 Fluid Power Innovation and Research Conference October 10-12, 2016 Hyatt Regency Hotel Minneapolis, Minnesota

Outline Background Energy use patterns Fuel economy and GHG standards Emission standards Trends in new engine design Projected engine and vehicle performance trends Carbon footprint of some alternative fuels Conclusions

Thermal efficiency of modern Thermal efficiency is defined as: engines ThermalEfficiency WorkOuput FuelEnergyInput It ranges from zero at idle to a maximum value at high load an moderate speed Spark ignition gasoline engine with 3-way catalyst ~ up to mid 30% range Passenger car Diesel ~ up low 40% range Heavy-duty truck Diesel ~ up to high 40% range Large (very) marine Diesel like that shown on right ~ 50% DOE target heavy-duty SuperTruck goal 55% Stringent emission standards must be met Thermal efficiency should not be confused with combustion efficiency, the fraction of fuel burned to CO 2, water. Often Typically greater than 90% spark ignition engines Often greater than 99% diesel engines

Transportation constitutes 28% of U.S. energy use 92% from petroleum which is 72% of petroleum use U.S. Energy Information Administration, Monthly Energy Review (April 2016),

Worldwide trends in fuel economy standards

CO 2 emissions fall as fuel economy increases

Gasoline consumption is expected to fall while diesel use is flat, sharp decrease in imports

We need to meet the challenge of increased efficiency while meeting ever tighter emission standards 0.14 Fleet Average NOx + NMOG (g/mi) 0.12 0.1 0.08 0.06 0.04 0.02 Proposed CA light-duty vehicle emission standards 0 2014 2015 2016 2017 Model Year 2018 2019 2020 2021 2022 S1 Heavy-Duty Light-Duty Source: Heavy Duty Diesels The Road Ahead, Elmar Boeckenhoff, US DOE DEER conference 2010 Source:http://www.arb.ca.gov/msprog/levprog/leviii/meetings/111610 /draft_sftp2_regs_nov2010.pdf

Review of current engine types Source: Diesel Power: Clean Vehicles for the Future - https://www1.eere.energy.gov/informationcenter/

Review of current engine types High efficiency, long life High cost, complex aftertreament lower efficiency, shorter life lower cost, simple aftertreament Source: Diesel Power: Clean Vehicles for the Future - https://www1.eere.energy.gov/informationcenter/

Diesel and spark ignition engines, nearly parallel paths advanced combustion Spark Ignition Direct injection Turbo-supercharging Downsizing Variable valve lift and timing Displacement management Adaptive control with advanced sensors Reduced friction Advanced cycles, Atkinson, Miller LTC modes, HCCI, PCCI, etc. Diesel Higher levels of turbosupercharging two stage High pressure, multiple injections Variable valve timing Adaptive control with advanced sensors Reduced friction Advanced aftertreatment Downsizing Waste heat recovery Turbocompound Organic Rankine Thermoelectric LTC modes, HCCI, PCCI, etc.

A new direction in engines Low Temperature Combustion (LTC) Diesel Diffusion burning of fuel jet High efficiency High compression ratio Lean combustion Very high combustion efficiency > 99% No throttle Low hydrocarbon and CO emissions Soot and NOx must be controlled by expensive exhaust aftertreament Diesel particle filter NOx control by SCR or lean NOx trap Fuel economy penalty Spark ignition Usually premixed Moderate efficiency Moderate compression ratio to avoid knock Chemically correct combustion Poor light load efficiency due to throttling Moderate combustion efficiency ~ 90% High hydrocarbon, CO, and NOx emissions, low soot emissions Hydrocarbon, CO, and NOx emissions easily controlled by relatively inexpensive 3-way catalyst How do we get the high efficiency of a Diesel engine without high NOx and soot emissions that require expensive exhaust aftertreament? A new combustion mode low temperature combustion (LTC) There are many flavors of LTC including, for example, homogeneous charge compression ignition (HCCI), partially premixed combustion (PPC), reaction controlled compression ignition (RCCI) and alphabet soup.

Low Temperature Combustion Alternative modes of engine combustion LTC, HCCI, PCCI etc Advantages: Low soot and NOx emissions Reduced heat loss = higher efficiency Offers opportunity to reduce need for emissions aftertreatment

Diesel LTC Conventional Combustion Diesel LTC High Oxygen Content Charge Air Low Oxygen/High EGR Charge Air Liquid Fuel First-Stage Ignition Soot & Soot Precursors NO x Soot Hydrocarbons High Cooled EGR Rates Increased Fuel Injection Pressure Modified Injection Timing to increase ignition delay, mixing time Early LTC Late LTC

Spark ignition compared to homogeneous charge compression ignition (HCCI) Homogeneous charge, like SI Compression ignition, like diesel Ignition controlled by chemical kinetics No propagating flame Multiple ignition sites Very fast combustion and high rate of pressure rise From: Numerical and Experimental Studies of HCCI combustion, Salvador Aceves, et al., Sixth Diesel Engine Emissions Reduction Workshop August, 2000.

Partially premixed Diesel LTC LTC lowers soot and NOx but increases HC and CO Lucachick, Glenn, Aaron Avenido, David Kittelson, and William Northrop, 2014. Exploration of Semi-Volatile Particulate Matter Emissions from Low Temperature Combustion in a Light-Duty Diesel Engine, SAE paper number 2014-01-1306.

Reaction controlled compression ignition, RCCI, using hydrous ethanol Ethanol in US currently anhydrous (>99% EtOH) Can save production energy up to 30% with 150 proof EtOH Goal: Expand the market for ethanol into diesel engines Hydrous ethanol has advantages for diesel engines when in dual fuel modes No PM and NOx aftertreatment Reduced need for EGR Increase fuel renewability Fang, Wei, David B. Kittelson, William F. Northrop, and Junhua Fang, 2013. An Experimental Investigation of Reactivity-Controlled Compression Ignition Combustion in a Single-Cylinder Diesel Engine Using Hydrous Ethanol, Proceedings of the ASME Internal Combustion Engine Division 2013 Fall Technical Conference, ICEF2013.

Emissions benefits of dual-fuel RCCI Data taken: single cylinder research engine Isuzu medium duty Engine parameters controlled 80% fumigant energy fraction 150 proof hydrous EtOH Results: Meets Tier 4 NOx/soot, engine out Same power range as diesel-only Complete control of engine required (OEM solution) RSM analysis underway to minimize emissions and fuel consumption Aftermarket development underway

Predicted trends in U.S. passenger car consumption By 2030 hybrid gasoline electric vehicles will consume roughly 1/3 the fuel of a current conventional vehicle Source: L. Cheah,J.Heywood/EnergyPolicy39(2011)454 466

One projection by CARB of what will be necessary to reduce passenger car CO2 emissions in California by 80% in 2050 In 2035 we will still as many vehicles relying on engines as today

Is there a quicker path to high mileage? Today s engine and driveline in a vehicle with 1985 acceleration and size would get 39 MPG, a 56% improvement! PSFI = P.S.F.I = (hp/lb). ft 3. MPG Source: L. Cheah,J.Heywood/EnergyPolicy39(2011)454 466

Heavy-duty engine efficiency targets and achievements, DOE Supertruck The long term goal is BTE > 55% Oscar Delgado and Nic Lutsey, The U.S. Supertruck Program, ICCT White Paper June 2014

Future fuels will be judged on carbon intensity Source: California's Low Carbon Fuel Standard Final Regulation Order, April 15, 2010 www.arb.ca.gov/regact/2009/lcfs09/lcfscombofinal.pdf

Conclusions Transportation engines are the main user of liquid petroleum fuels Both gasoline and diesel engines / vehicles are making large gains in efficiency Projected substantial reduction in gasoline consumption Diesel consumption flat due to increasing worldwide use of diesel engines, especially heavy-duty Sharp decreases in emissions have been achieved but challenges remain NOx Cold start Old vehicles Future fuels should be judged on their carbon footprints

Thank you, questions?

Additional materials

NOx emissions from buses in real-world operation The work reported here is part of a wider program on performance, emissions, and fuel economy of modern transit buses Real world NOx emissions Many current reports of real drive emissions exceeding certification standards Due to large differences between certification test cycles and real-world driving Sadly, in some cases, due to cheating, cycle beating by the manufacturer not the case in this work! This program has primarily focused on 2013 technology urban buses 2013 engine MY buses met lab certification but Emitted well above certification levels under real-world driving conditions But complied with Not to Exceed Standards, perfectly legal! Highly transient real-world cycle Never in NTE window long enough for exceedance Cummins has an ongoing program to improve real world emissions and has recalibrated 2015 bus engines Metro transit bought 120 2015 Cummins powered buses We evaluated NOx emission from a randomly selected 2015 MY bus from Metro Transit fleet

Test buses Bus Manufacturer Layout 2013 MY 1503 - Standard Diesel 2013 MY 7290 - Series Hybrid 2013 MY 7327 - Parallel Hybrid 2015 MY 1713 - Standard Diesel GILLIG Low Floor New Flyer Xcelsior TM GILLIG Hybrid GILLIG Low Floor Engine Cummins ISL 8.9L Cummins ISB 6.7L Cummins ISB 6.7L Cummins ISL 8.9L Transmission ZF-Ecolife TM BAE HybriDrive TM Allison Electric Drives TM ZF-Ecolife TM Emissions AC Compressor Thermoking Belt Driven Power Steering Engine Fans Air Compressor Mechanical Engine Coupled Mechanical Engine Coupled 2013 Certified SCR and DPF Thermoking 3-Phase Electric 230VAC 3-Phase Electric 2015 Certified SCR and DPF Thermoking Belt Driven Thermoking Belt Driven Mechanical Engine Coupled EMP - 28VDC Electric 8 or 9 Fan 230VAC 3-Phase Electric Mechanical Engine Coupled Mechanical Engine Coupled Mechanical Engine Coupled On-road Evaluation Of Energy Flows And Emissions From New Technology Conventional And Hybrid Transit Buses, Andrew Kotz, William Northrop and David Kittelson, 26th CRC REAL WORLD EMISSIONS WORKSHOP Newport Beach, California, March 13-16, 2016

Test routes selected normal passenger service Low Speed Route Speed: 17mph KI: 2.4 s -1 Mid Speed Route Speed: 25mph KI: 1.5 s -1 KI = Characteristic Acceleration Aerodynamic Velocity High Speed Route Speed: 28mph KI: 0.6 s -1 On-road Evaluation Of Energy Flows And Emissions From New Technology Conventional And Hybrid Transit Buses, Andrew Kotz, William Northrop and David Kittelson, 26th CRC REAL WORLD EMISSIONS WORKSHOP Newport Beach, California, March 13-16, 2016

Test Matrix wide range of Summer 13 conditions 2013-14 test program testing 1503, 7290, 7337: conventional, series hybrid, parallel hybrid Winter 14 Spring 14 Summer 14 2015-16 test program testing 1503 and 1713 Summer 15 Winter 16 Min. Temperature 58 ºF -17 ºF 39 ºF 42 ºF 58 ºF 6 ºF Max. Temperature 90 ºF 38 ºF 78 ºF 91 ºF 90 ºF 46 ºF Avg. Temperature 71 ºF 10 ºF 56 ºF 71 ºF 77 ºF 26 ºF Good Test Days 9 19 13 16 9 9 Start Date 8/5/2013 1/13/2014 5/5/2014 7/14/2014 8/9/2015 2/8/2016 End Date 8/20/2013 2/13/2014 5/20/2014 8/14/2014 9/5/2015 2/20/2016 On-road Evaluation Of Energy Flows And Emissions From New Technology Conventional And Hybrid Transit Buses, Andrew Kotz, William Northrop and David Kittelson, 26th CRC REAL WORLD EMISSIONS WORKSHOP Newport Beach, California, March 13-16, 2016

Very low real-world NO X emissions from 2013 retro and 2015 buses New study operation over 10 days: 2013 MY 258 Hours 2015 MY 260 Hours 1.8*10 6 Data Entries On-road Evaluation Of Energy Flows And Emissions From New Technology Conventional And Hybrid Transit Buses, Andrew Kotz, William Northrop and David Kittelson, 26th CRC REAL WORLD EMISSIONS WORKSHOP Newport Beach, California, March 13-16, 2016

Real-world operating conditions compared to FTP FTP certification cycle far from bus operating conditions *Kotz, A. J.; Kittelson, D. B.; Northrop, W. F. Lagrangian Hotspots of In-Use NOx Emissions from Transit Buses. Environ. Sci. Technol. 2016 DOI: 10.1021/acs.est.6b00550.

Particle Emissions from Gasoline Spark Ignition Engines (SI) Why do gasoline engines produce less PM that diesel? Simply stated combustion is much more premixed Two major classes of gasoline SI engines Port fuel injection, PFI Until recently the most common design Stoichiometric operation, 3-way catalyst Low particle emissions except during cold start and high load Small, semi-volatile particles under cruise conditions Gasoline direct injection GDI, DISI Better fuel economy than PFI Mainly stoichiometric operation, 3-way catalyst Particle emissions intermediate between PFI and Diesel Low semi-volatile fraction Lean burn, better fuel economy but higher PM and PN emissions Likely to need filters to meet PN

Passenger car particle standards, mass, number, size Trend line based on Maricq, 2010, shaded areas based on data from Giechaskiel, et al., 2012

Passenger car particle standards, mass, number, size Will filters be needed? Trend line based on Maricq, 2010, shaded areas based on data from Giechaskiel, et al., 2012