Super-efficient Methanol Engines Using Spark Ignition and Exhaust Heat Recovery +

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1 Super-efficient Methanol Engines Using Spark Ignition and Exhaust Heat Recovery + Daniel R. Cohn + + MIT Energy Initiative PROMSUS Workshop Gothenburg, Sweden +Supported by Arthur Samberg Energy Innovation Fund ++ In collaboration with Leslie Bromberg

2 Objectives Engine efficiency up to 25 % greater than diesel engine in heavy duty vehicles and ships Engine size ~ 40 % smaller that of diesel for same torque Lower emissions of nitrogen oxides and particulates than diesel

3 Diesel-Like High Efficiency Using High Octane of Methanol High octane of methanol prevents knock (unwanted detonation) that limits performance of spark ignition engine Allows high compression ratio and high level of turbocharging / downsizing Provides 30 % efficiency gain over standard spark ignition engine Demonstrated in engine tests (EPA Ann Arbor)

4 Emissions and Cost Diesel engine uses complex and expensive exhaust gas treatment system (urea SCR + particulate filter) In contrast spark ignition engine uses simple and highly effective three way catalyst Spark ignition methanol engine + exhaust treatment system cost could be 30 to 50 % less than diesel for truck ; and also have lower emissions

5 Efficiency gain relative to standard gasoline engine Super -efficient Spark Ignition Methanol Engines 55%- 50%- 40%- exhaust heat recovery 30%- Diesel engine 20%- 10%- Turbocharging and downsizing High compression ratio Removal of knock limit (higher octane) Exhaust heat recovery

6 Waste Heat ~ 55% of energy produced by combustion is lost as heat ( half to exhaust, half to coolant) With optimized heat recovery in spark ignition methanol engine ~ 80 % of exhaust heat energy can be recovered Around 25 % of heat energy produced by combustion can be recovered and then converted into mechanical power

7 Optimized Waste Heat Recovery 1. Spark ignition engine ( Stoichiometric fuel/air ratio provides higher exhaust temperature and better heat transfer than diesel) 2. Reform methanol into hydrogen-rich gas that has more chemical energy and is then combusted in engine 3. Open Rankine cycle: further increase heat recovery 4. Metallic foam heat exchanger

8 Waste Heat Recovery Using Reformation Of Methanol Low temperature catalytic reforming CH 3 0H 2H 2 + CO (hydrogen- rich gas)endothermic decomposition H 2 rich gas has more energy than methanol

9 Alcohol Rankine Cycle Rankine cycle uses heat to convert pressurized liquid into hot gas that does mechanical work Gas has energy from both chemical conversion of methanol to H2 rich gas and increased heat energy Hot gas is used to do mechanical work Gas is introduced into engine ( open Rankine cycle) rather than being condensed into liquid

10 Open Alcohol Rankine Cycle Temperature and heat rejection limit conventional Rankine cycle performance For alcohols, energy recovery increased by reforming alcohol Use fuel as working fluid Low temperature, endothermic reformation to hydrogen-rich gas Methanol and hydrous ethanol can recover > 80% of the exhaust heat Absorbs heat from engine coolant, reducing radiator design, as opposed to conventional Rankine cycle that increases load to radiator 20-25% fuel efficiency increase energy recovery with turbine and/or injection into engine Option 1: Turbo-generators Option 2: Fuel injection energy recovery

11 Open Alcohol Rankine cycles Turbine recovery Engine recovery

12 Metallic Foam Heat Exchanger New compact heat exchanger increases reformer effectiveness Use of metallic foams improves exhaust heat transfer to gas - great thermal contact with gas (lots of surface area) However, because of very high porosity, foams have poor thermal conductivity This drawback is removed by combining foam with fins that have high thermal conductivity

13 porous metal foams

14 Foam on Fins Heat exchanger For Exhaust Heat Recovery Need efficient, compact heat exchanger design for vehicular applications Foam metals are very attractive High surface heat transfer coefficient, However, have low thermal conductivity Solution: Foam on fins

15 Cryogenic heat exchanger current lead for superconducting applications

16 Use of Alcohol Rankine Cycle with Diesel Compression Ignition Use compression ignition of a small amount of diesel to initiate flame front combustion of hydrogen-rich gas Dual fuel engine: diesel and hydrogen-rich gas (generated by reforming of methanol) Could obtain similar efficiency gain to spark ignited engine

17 Summary Methanol offers potential for very effective waste heat recovery Recover heat from engine exhaust (major) and coolant (minor) Avoid expander and condenser needed in conventional Rankine cylce Potential engine efficiency ~ 55-60% Rivals fuel cells Considerably exceeds diesel Very low pollutant emissions that are easily controlled Cost attractive Could significantly increase attractiveness of using renewable methanol for heavy vehicles and ship propulsion