2. Scope for Development in I. C. Engine Design P M V Subbarao Professor Mechanical Engineering Department Means to move towards Ideal Cycle Performance Limits !!!

3. Future Targets for LCVs

4. Space for innovation in Conventional Concepts - factor of 2 in efficiency  Ideal Otto cycle engine with CR = 8: 52%  Real engine: 25 - 30%  Differences because of Throttling losses Heat losses Friction losses

5. Space for innovation - infinite in pollutants non-equilibriumPollutants are a non-equilibrium effect Burn: Fuel + O 2 + N 2  H 2 O + CO 2 + N 2 + CO + UHC + NO On A Faster Expansion: CO + UHC + NO “frozen” at high level With slow expansion, no heat loss: CO + UHC + NO  H 2 O + CO 2 + N 2 But how to slow the expansion and eliminate heat loss? Worst problems: cold start, transients, old or out-of-tune vehicles. 90% of pollution generated by 10% of vehicles !!!!

6. Space for innovation - very little in power  IC engines are air processors  Fuel takes up little space  Air flow = power  Limitation on air flow due to  “Choked” flow past intake valves  Friction loss, mechanical strength - limits RPM  Slow burn  Majority of power is used to overcome air resistance  Majority of power is used to overcome air resistance - smaller, more aerodynamic vehicles beneficial

7. Clues for Improvement- alternative fuels : Natural Gas Somewhat cleaner than gasoline, non-toxic High octane without refining or additives (≈ 110) No cold start problem Half the CO 2 emission of EVs charged with coal-generated electricity Dual-fuel (gasoline + natural gas) easily accommodated Lower energy storage density (≈ 1/4 gasoline) Lower power (≈ 7% less) Attractive for fleet vehicles with limited territory Renewable bio-methane could increasingly take the place of fossil-fuel gas. The IC Engine is not addicted to fossil fuels …. WE ARE!

8. Clues for Improvement - alternative fuels – Alcohols/Bio-Diesels  Slightly cleaner than gasoline  High octane (≈ 95)/ varying (48 – 67) Cetane  Not cost-effective without price subsidy  Lower storage density (methanol ≈ 1/2 gasoline)  Toxic combustion products (aldehydes) Attractive to farm states

9. Clues for Improvement- alternative fuels - Hydrogen Ultimate clean fuel Excellent combustion properties Ideal for fuel cells Very low storage density (1/10 gasoline) Need to manufacture - usually from electricity + H 2 O Attractive when we have unlimited cheap clean source of electricity and breakthrough in hydrogen storage technology