1. Phase 2 GHG Rules for Trailers
28-July-2016
Tony Greszler and Thomas Reinhart

2. SwRI Involvement SwRI is an independent, non-profit R&D organization
SwRI has conducted research for EPA and NHTSA to support the development of Phase 2 regulations
Test procedure development and evaluation
GEM model development
Simulation study of engine and vehicle technologies available for compliance
SwRI also supports the efforts of OEMs and suppliers to develop and certify products

3. SwRI Coast-Down Testing for EPA
9 tractors
53’ and 28’ trailers
Skirts and tails
70 – 80 tests in all
Purpose: determine the average effect of trailer aero devices over a range of tractors and trailers
Final report will be published soon on the EPA docket
SwRI also does aero device certification testing for manufacturers

4. Trailer GHG Regulations
Starts with MY requirements can be met with Smartway approved features
Aero and tires for box vans
Only tires for other trailers
Subject to EPA approval and possible revision if new data warrants
Starting with MY 2021, new standard becomes fully applicable
Small business manufacturers provisions
One year delay
Simplified provisions
Covers majority of heavy-duty trailers pulled by tractors
Only applies to new trailers – no retrofit requirements
Excludes pintle hook type trailers (second pup?)
Trailer manufacturers responsible for compliance

5. GEM Calculation for Trailers Establishes Certification for each trailer (grams/ton-mile)
Weight Reduction
Aero
Tires
TRRL units:
Kg/metric ton
CdA units: m2
WR units:
Pounds
; 1.0 otherwise
Otherwise, C5 = 1.0

6. Trailer Aero Method Aero test is based on tractor procedures
Coast down, constant speed, wind tunnel, CFD
CdA represents tested trailer pulled by a “standard” tractor
Long trailer devices to be tested with 53’ trailer
Short trailer devices to be tested with 28’ trailer
Testing compares change in CdA between test trailer and baseline trailer

7. Baseline Trailers
Baseline trailer is a trailer meeting the specifications for a Phase 1 standard trailer in (g)(1)
Box van with no aero devices
For refrigerated box vans, install an HVAC unit on the baseline trailer
For short trailers, use a 28-foot baseline trailer with a single axle
Same specifications as the Phase 1 standard trailer, except as needed to accommodate the reduced trailer length.

8. Trailer Aero Testing Trailer manufacturer selects the test tractor
Must be phase 2, bin III or better for aero
Sleeper for long box trailer; day cab for short box
There is flexibility to pick a tractor that best matches the trailer aero design, but works poorly with the baseline
Unclear how much scope there is for improving numbers with this approach
The draft regulation proposes using only zero yaw data
Aero devices are more effective at yaw
Not clear how coast-down or constant speed can be used for zero yaw assessment, since there are rarely zero wind conditions. CFD or wind tunnel are acceptable (since they can assess zero yaw CdA)

9. Trailer Aero Testing
The default method for measuring CdA is a coastdown procedure
If approved in advance, you may instead use one of the alternative methods
Reduced Scale Wind Tunnel
CFD
Constant speed testing
Note: wind tunnel and CFD tend to yield lower Cd values than coast-down tests
This may not be significant because of A to B comparison process for trailers

10. Coast-down Aero Testing
Requires careful testing with specific instrumentation and data acquisition processes.
Test track requirements
Need ~3 miles without obstructions or other traffic
Flat as possible with corrections for any elevation changes (elevations must be measured)
Wind within test limits, preferably near zero
Most phase 2 tractor data has been acquired either on SwRI test road or Cape Canaveral shuttle landing strip
Data analysis is complex

11. Alternatives to Testing Each Trailer Specification
Aero device manufacturer tests add-on devices on a generic trailer
Device manufacturer submits data to EPA for approval
Trailer manufacturer applies delta CdA to trailers using the tested device
If multiple devices are deployed:
Fully count the technology with largest delta CdA value, discount the second by 10 percent, and discount each of the remaining additional technologies by 20 percent
Alternatively, the device manufacturer can test with multiple devices

12. Aero Audit Process
Confirmatory Audit – applies to trailer used for certification
Selective Enforcement Audit – applies to any production trailer
Purpose: verify that trailer with aero devices falls into claimed bin
Process
Agencies propose to use coast-down regardless of certification method used by manufacturer
Agencies recognize testing is highly variable
Proposed compliance is based on statistical analysis of up to 100 paired high-speed and low-speed runs
Statistics are complicated and unclear for comparison of test trailer vs. baseline
Proposed method is included in NODA memorandum:
“Additional Discussion of Selective Enforcement Audit and Confirmatory Testing for Aerodynamic Parameters for Combination Tractors and for Trailers”

13. Key Questions for Trailer Aero
How/when will you know what tractors meet phase 2 bin III or better?
Which test method will provide largest CdA difference?
Should multiple devices combine using EPA approximation or by testing in combination?
Will generic device tests yield better or worse results than testing on a specific trailer model?
How will coast-down or constant speed data be translated to zero yaw delta CdA?
How will audits be performed and what compliance margin should be applied to assure passing an audit or confirmatory test?
Note variability is doubled due to A-B comparison requirement.
How will the statistical compliance test work with A to B comparison?
Recent EPA memo indicates use of coast-down for audit but lacks clarity
How much will coast-down results deviate from alternative certification methods?
Tire and road surface impacts on coast-down testing?
How much variation in test conditions will be acceptable between A and B test?
Is there industry data to support the proposed bin delta CdA values?
What data is required to approve alternatives to coast-down testing?

14. Certification and Reporting
Manufacturers decide which technologies to offer
Use the equation to determine the GHG performance of the packages they will offer
Provide projected sales data to show capability to comply over the certification year
Maintain records of specifications sold and resulting GHG, with a sales volume based average for the model year
Provide two reports to EPA
Production volumes for each configuration (with confirmation that all trailers applied the technology packages outlined in their application, if not using averaging)
Summary of families and subfamilies, and CO2 emissions and fuel consumption results from the equation for all of the trailer configurations built (only required if using averaging provision)

15. Averaging Provisions
Rather complicated - see section IV.D.6.a of preamble (p 318 of draft rule)
Single MY, no banking, no trading
Only available to dry and refer box trailers
Any deficit can be carried over with three years to resolve (not available for non-box and non-aero trailers)
No averaging for partial aero box trailers or non-box trailers

16. Contact Information
Tom Reinhart – Institute Engineer
Tony Greszler – Consultant