# Presentation: 193315

## Designing the Clean and Fuel Efficient Engine for theTwenty-First Century

*Charles L. Gray, Jr.*
*Advanced Technology Support Division*
*USEPA Office of Air & Radiation*
*Office of Mobile Sources*

## Fifty Years Ago...

## The Federal Role in Efficiency & Emissions

- R&D Partnerships
-  ( PNGV )

- Enabling Policy
- ( tax credits )

- Regulatory Policy
- ( CAFE, Tier 2 )

## Defining “Efficient”:

- 80 mpg
- Meets Tier 2 emissions standards
- Meets all Federal safety standards
- Size, performance, cost of ownership comparable to today’s midsize family sedans
- Implies leapfrog technology (engine, drivetrain)

## Defining “Clean”: Tier 2

- Establishes 7 certification emission bins applicable to all light duty vehicles
- Establishes interim & final manufacturer fleet average NOx standards
- Heavier light trucks get longer, but ...
- ...by 2009, eliminates explicitly different standards for car & light truck categories

## Phase-In of the ProposedTier 2 NOx Fleet Averages

- Tier 2
- Final
- 0.07 gpm

## Proposed Tier 2:Maximum NOx Levels 

**Light Trucks > 6000 lb GVWR**

## Proposed Tier 2:Maximum PM Levels 

**Light Trucks > 6000 lb GVWR**

## Ultimately Future Engine Designs Should Help Vehicles Deliver...

## Engine Equivalent Stringency to Tier 2

## HD Engine Goals

## Research Focus:  Achieving Integrated Solutions...

**Combustion System**

**Fuel**

**Aftertreatment**

***High ***
***Efficiency***

***Low***
***Emissions***

## Conventional SI with Premixed Charge + Gasoline = Low Emissions, but Inefficient

- Homogeneous charge, inherently low PM

**Gasoline**

**TWC**
**EGR**

***Low***
***Efficiency***

***Low***
***Emissions***

- High peak temp = high NOx, but stoich operation allows TWC

*Throttling and low compression ratios reduce efficiency*

## Conventional CI Direct Injection + Diesel Fuel = Efficient but has High Emissions

- High compression & unthrottled = high efficiency...

**Diesel**
**Fuel**

**EGR**

***High***
***Efficiency***

***High***
***Emissions***

*...**But stratified charge = high PM*

*High peak combustion temperatures = high NOx; lean operation prevents use of TWC*

## Alternative Fuel Research Engines Already Clear “High Bar” Efficiencies...

- Renewable alcohol research engine
- Two different combustion concepts
- Efficiencies exceed state-of-the-art diesel

## ...While Exhibiting Low Engine-Out NOx

## Approach Employs late DI with Stoichiometry, on Methanol

- Predicted advantage for fuels with no or one carbon bond...

**MeOH**

**TWC**
**EGR**

***High***
***Efficiency***

***Low***
***Emissions***

- Implies additional focus:  similar concept on EtOH, DME

*Raises fuel infrastructure issues*

**EtOH?**
**DME?**

## Research Opportunity: Gasoline/Diesel-Like Fuels at Stoich

- If efficiency is obtained through high compression, high expansion + unthrottled...

**TWC**

***?***
***Emissions***

- How can the engine be operated at stoich, so as to allow TWC?

## Research Opportunity:  Lean Burn on Gasoline/Diesel-Like Fuels

- ?

- If engine is operated with lean burn...

**Gasoline-like?**
**Diesel-like?**

***High***
***Efficiency***

***?***
***Emissions***

**Lean Burn**

- Need more research on NOx adsorbers, plasma cats, PM traps

- Includes issue of achieving intermittant rich operation to purge adsorber

## New Fuels Enable Advanced Aftertreatment

- Low sulfur
- Somewhat dependent on combustion approaches not yet demonstrated
- NOx/PM traps, SCR, plasma cats
- If separate/segregated fuel required, should we ramp up alt fuel focus now?

## Future Prospects for Even Higher Efficiency

- Lower heat rejection
- Cost-effective bottoming cycles
- especially in hybrid applications
- focus on parallel hybrid w/                 load-leveled engine operating			 in high-load, high efficiency 			regime

## Twenty Years from Now...