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High Efficiency Combustion Engines – What is the limit?
Prof. Bengt Johansson Lund University
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Outline Introduction Combustion engines Conclusions
The future is hard to predict Options Other combustion engines? Fuel cells? Batteries? Combustion engines What is high efficiency? Combustion, thermodynamic, gas exchange and mechanical efficiencies. All four must be high. What options do we have? Combustion to enable high efficiency Spark Ignition Compression Ignition HCCI Partially Premixed Combustion Can we do something about engine design? Conclusions
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100.0% internal combustion engines Today of all cars and trucks have
The total fleet is about cars and trucks The electric fleet is less an i.e. 0.1%
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“Prediction is very difficult especially if it is about the future”- Niels Bohr
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Newsweek April 28, 1975
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”Den som ser framåt utan att se bakåt får se upp” - Per Gillbrand
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Car of the future 1950-60: Gas turbine
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Car of the future 1950-60: Gas turbine
“Timetable for Next Car Engine : The Gas Turbine and Its Future” Business Week, April 2, 1955, page 134+ THEY ESTIMATE by , ,000 cars , ,900,000 ,500, ,500,000 ,000, ,000,000
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Car of the future 1970: Stirling
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Car of the future 1980: ….
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Car of the future 1990: Battery Electric
GM EV-1
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Car of the future 2000: Fuel Cell
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Car of the future 2000: Fuel Cell
“It is generally accepted that fuel cell vehicle production will follow a timeline as follows: Starting in : • First production FCVs tested on public roads in US, Europe and Japan in demonstration fleets. Around • Second generation fuel cell systems incorporated into FCVs and the expansion of FCV fleets in the US, Europe and Japan. Starting in 2010 • Marketing of commercially viable FCVs at affordable prices - this will be the first step toward ultimately replacing the conventional internal combustion engine models.” August 29, 2002, Bloomberg News : ”Larry Burns, GM’s vice-president for R&D: “GM’s goal is to be the world’s first company to produce one million fuel cell vehicles a year,” and that GM is looking to sell hundreds of thousands of fuel cell vehicles between 2010 and 2020
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Car of the future 2010: Battery Electric
Carlos Ghosn CEO Renault/Nissan 2010: “Nissan Will Sell 500,000 Electric Cars a Year by 2013” He predicted that 10 percent of the world car market would be electric vehicles by “There is no doubt in the minds of anyone in the industry that this is going to be a big factor in the industry,” he said.
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Car of the future 2010: Battery Electric
Reuters news flash Sept : Nissan faces battery plant cuts as electric car hopes fade Ghosn dropped extra battery sites planned for both alliance carmakers, leaving Nissan with the entire production capacity of 220,000 power packs through the NEC joint venture, AESC. But that still far exceeds the 67,000 electric cars Renault-Nissan sold last year, and even the 176,000 registered to date. A pledge to reach 1.5 million by 2016 has been scrapped.
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Toyota: Elbilen behöver Nobelprisbatteri
Tekniken som behövs för att göra elbilar användbara är inte uppfunnen än Körsträckan är så kort med en elbil, och laddtiden är så lång, summerar Kato. Med den tekniknivå vi befinner oss på i dag behöver någon uppfinna ett batteri så bra att det vinner Nobelpris. För att kunna konkurrera med dagens bensindrivna bilar behövs så mycket batterier att det ökar kostnaderna och laddtiderna. - Antalet kunder som är nöjda med elbilens korta räckvidd är begränsad, säger han. Men blir intresset för sådana bilar plötsligt större, då är vi beredda att leverera. Av: Håkan Abrahamson, Ny teknik 10 juli 2014
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Toyota: Elbilen behöver Nobelprisbatteri
I en intervju i Automotive News ger han tummen ner för satsningen på elbilar, och säger att Toyota nu lägger sin tillverkning av elbilar. Företaget tror att alternativet till bensin och diesel heter vätgas. Nästa år lanserar Toyota en bränslecellbil, och även andra tillverkare ligger startgroparna med den sortens drivning. Vid det laget erbjuder Toyota inte längre någon helt eldriven bil, säger Kato. De små serier av elbilar som nu finns på programmet, minibilen eQ och RAV4 EV, läggs ner i slutet av det här året. Av: Håkan Abrahamson, Ny teknik 10 juli 2014
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Battery performance “The active material for the anode and the cathode which are assumed to be a carbon-based anode (~2.7 g/Ah) and a Co-based cathode (~7.3 g /Ah) for the Li-ion cell. The specific capacity of the couple is therefore ~100 Ah/kg which combined with the voltage of 3.85 V for this couple leads to the 385 Wh/kg number” Source: Private communications with Prabhakar Patil, CEO, LG Chem, Battery Div. Nov. 4, 2011
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Li-ion battery performance is now at 52% of theoretical limit
40/250=0,160 55/245=0,225 55/315=0,175 70/370=0,189 80/240=0,333 20/810=0,025 20/135=0,148 70/570=0,123 180/790=0,228 130/459=0,283 200/385=0,519 Source: Private communications with Prabhakar Patil, CEO, LG Chem, Battery Div. Nov. 3, 2011
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Electric Vehicle – Storage capacity
Energy density increased 1 order of magnitude Specific energy increased a factor of 4-5 200 years Even a low efficient ICE will have a better energy density and specific energy under normal running conditions. For the same rated power an electric vehicle is much heavier than a ICE. Cost of batteries! 20 Source: Tarascon and D. Foster Keynote speech at ASME ICES 2009
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Electric Vehicle – Electricity source?
Q: What is the similarity of a steam engine and a battery electric vehicle? A: They both run on coal… 21
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Summary on alternatives
They have all promised much but delivered little! There is today not a viable alternative to the Internal Combustion Engine We must focus our little resources to improve what will be the prime mover of the future, not unrealistic scenarios The ICE can be improved very much in the future
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Car of the future, today Smaller car with small ICE in combination with hybrid system. Fuel consumption of l/100km (<25 g/km CO2) ICE 60% fuel efficient with below zero levels of local emissions like NOx, PM, HC and CO. The 40% heat loss is used for heating the car. At least 100% CO2-neutral with renewable fuel
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Car of the future, in the future
?
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Car of the future, the Crystal Ball?
German architect André Broessel of Rawlemon
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Outline Introduction Combustion engines Conclusions
The future is hard to predict Options Other combustion engines? Fuel cells? Batteries? Combustion engines What is high efficiency? Combustion, thermodynamic, gas exchange and mechanical efficiencies. All four must be high. What options do we have? Combustion to enable high efficiency Spark Ignition Compression Ignition HCCI Partially Premixed Combustion Can we do something about engine design? Conclusions
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Energy flow in an IC engine
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Combustion modes + Clean with 3-way Catalyst
- Poor low & part load efficiency + High efficiency - Emissions of NOx and soot Combustion modes Spark Ignition (SI) engine (Gasoline, Otto) Compression Ignition (CI) engine (Diesel) + High efficiency + Ultra low NOx Combustion control Power density Homogeneous Charge Compression Ignition (HCCI) Spark Assisted Compression Ignition (SACI) Gasoline HCCI Partially premixed combustion (PPC) Diesel HCCI + Injection controlled - Less emissions advantage
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ICE research in Lund vs. time
High eff. themodynamics PPC CCV=Cycle to Cycle Variations in Spark Ignition Engines GDI= Gasoline Direct Injection 2-S= Two Stroke engine VVT=Variable Valve Timing HCCI=Homogeneous Charge Compression Ignition SACI=Spark Assisted Compression Ignition PPC= Partially Premixed Combustion HCCI SACI VVT 2-S GDI GenDiesel CCV Si gas engine Si gas engine 1990 1995 2000 2005 2010 2015
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Emission focus vs. time SOx Particulates NOx CO CO2 HC 1970 1980 1990
2000 2010 2020
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HCCI -Thermodynamic efficiency
Saab SVC variable compression ratio, VCR, HCCI, Rc=10:1-30:1; General Motors L850 “World engine”, HCCI, Rc=18:1, SI, Rc=18:1, SI, Rc=9.5:1 (std) Scania D12 Heavy duty diesel engine, HCCI, Rc=18:1; Fuel: US regular Gasoline SAE
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All four efficiencies SAE keynote Kyoto 2007
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Net indicated efficiency= ηC ηT ηGE
SI std SI high HCCI +100% VCR Scania
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Brake efficiency SI std SI high HCCI VCR Scania
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Net indicated efficiency= ηC ηT ηGE
47% SI std SI high HCCI VCR Scania
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PPC - Diesel engine running on gasoline
HCCI: ηi=47% => PPC: ηi=57%
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Partially Premixed Combustion, PPC
PCCI CI HCCI PPC Def: region between truly homogeneous combustion, HCCI, and diffusion controlled combustion, diesel SAE
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Experimental setup, Scania D12
Bosch Common Rail Prailmax 1600 [bar] Orifices 8 [-] Orifice Diameter 0.18 [mm] Umbrella Angle 120 [deg] Engine / Dyno Spec BMEPmax 15 Vd 1951 [cm3] Swirl ratio 2.9 Fuel: Gasoline or Ethanol 38 38 SAE
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Efficiencies 17.1:1 39 SAE
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Efficiencies 14.3:1 40 100 95 90 85 80 Combustion Efficiency [%] 75
Thermal Efficiency 70 Gas Exchange Efficiency Mechanical Efficiency 65 60 55 50 4 6 8 10 12 14 16 18 Gross IMEP [bar] 40 SAE
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Emissions Better tuned EGR- combination 41
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Emissions – different fuels
SAE
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Stable operational load vs. fuel type
Tested Load Area Stable operational load vs. fuel type 43 43
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Efficiency with Diesel or Gasoline
Average improvement of 16.6% points at high load by replacing diesel fuel with gasoline! D13 Diesel was calibrated by Scania to meet EU V legislation.
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PPC Combustion Summary
PPC has shown very high fuel efficiency Indicated efficiency of 57% at 8 bar IMEP Indicated efficiency of 55% from 5-18 bar IMEP With 70 RON fuel we can operate all the way from idle to 26 bar IMEP Emissions are below US10/Euro 6 without aftertreatment for NOx, PM, HC and CO! The fuel properties are critical for PPC load range
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ICE research in Lund vs. time
High eff. themodynamics PPC CCV=Cycle to Cycle Variations in Spark Ignition Engines GDI= Gasoline Direct Injection 2-S= Two Stroke engine VVT=Variable Valve Timing HCCI=Homogeneous Charge Compression Ignition SACI=Spark Assisted Compression Ignition PPC= Partially Premixed Combustion HCCI SACI VVT 2-S GDI GenDiesel CCV Si gas engine Si gas engine 1990 1995 2000 2005 2010 2015
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Energy flow in an IC engine
✔ ✔ ✖ ✖
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High efficiency thermodynamics: Simulation results from GT-power
Indicated efficiency 64% Brake efficiency 60.4% System layout is confidential
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Outline Introduction Combustion engines Conclusions
The future is hard to predict Options Other combustion engines? Fuel cells? Batteries? Combustion engines What is high efficiency? Combustion, thermodynamic, gas exchange and mechanical efficiencies. All four must be high. What options do we have? Combustion to enable high efficiency Spark Ignition Compression Ignition HCCI Partially Premixed Combustion Can we do something about engine design? Conclusions
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The future ICE Highest possible fuel efficiency
Low enough emissions of NOx, PM, HC, CO Capable of using renewable fuels And the basic requirements of all products: Very high durability Low service requirements High power/mass ratio High power/volume ratio Low cost
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Future Optimize the combustion process Improve the thermodynamics
PPC Diesel Spark Ignition (prechamber) Improve the thermodynamics A compression ratio,Rc of 70:1 and lean mixture (γ=1.38) gives a thermodynamic efficiency of 80%! Work with engine systems, not only details
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What is the long term future?
Active rate shaping What is the best Rate of Heat Release, RoHR, for maximum thermodynamic efficiency? The analog fuel injector with real time control of fuel flow and hence RoHR (with short ignition delay) using FPGA Fuels and engine interactions Best fuel for a combustion process Fuel flexible combustion process Natural gas/Biogas LNG/LBG-intercooler Hybrids The 2, 4, 6 concept Air Hybrid Heat transfer, coatings etc.
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Prof. Bengt Johansson Lund University
High Efficiency Combustion Engines – What is the limit? “It all starts at 40 and ends at 60” ( %engine efficiency that is, not life) Prof. Bengt Johansson Lund University
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Thank you!
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High Efficiency Combustion Engines – What is the limit?
Prof. Bengt Johansson Lund University
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