"E-Diesel" fuel

[philip]

Cummins terms 'e-diesel' an 'extreme fire hazard'

Jack Peckham
San Diego -- At Society of Automotive Engineers Powertrain & Fluids Conference here, Cummins announced that it views "e-diesel" blends of alcohols and diesel fuel "an extreme fire hazard and under certain circumstances an explosive hazard."

However, if such "e-diesel" blends penetrate the commercial marketplace, then Cummins also wants to know what might happen to engine equipment. So, it launched an investigation of "e-diesel" impact on engine components, heat balance and fuel economy.

The study investigated a blend of 88.7% diesel, 10% ethanol, 1.3% emulsifying additive and 0.001% cetane improver (to overcome the cetane degradation effect of ethanol).

Tests on the non-road, EPA "Tier-i" emissions certified Cummins C8.3 engine found that "a greater than expected volume of E-diesel was required to operate the compression ignition engine at the same torque-speed compared to No. 2 diesel," Cummins researcher Michael Mendoza explained in a paper (SAE 2002-01-2847) here.

This is an engine typically used in agricultural tractors, combines, box trucks and cement trucks, Mendoza said.

Cummins had to "up-fuel" the injector pump by 10% to compensate for the lower energy content of ethanol compared to diesel, he said. "Although unchecked, Bosch pump stress limits were very likely exceeded," Mendoza warns.

* Warranty Issues

"Under no circumstances should the fullload fueling level on Cummins engine be adjusted outside the factory specifications," he said. "Increasing the full-load fueling of emissions certified engines is prohibited by law. On certified and non-certified engines, increasing the fueling will void the engine and/or fuel system manufacturer's warranty."

Thermal efficiency degradation on the ethanol blend resulted in a 9% fuel penalty on a volume basis, Cummins found.

While exhaust seat temperatures increased from "e-diesel" fueling, Cummins found no significant difference in component temperatures elsewhere on the engine. (Gont. p10)

Meantime, a separate investigation of "e-diesel" lubricity effects on fuel system equipment found that bench lubricity tests "do not adequately predict actual pump rig performance," according to a Lubrizol paper (SAE 2002-01-2849).

"While all e-diesel blends tested showed very good bench test performance, not all e-diesel blends passed the Bosch pump rig test," Lubrizol found.

The best-performing "e-diesel" blend in the Bosch pump rig test "used a low level of a low-acid type of lubricity improver," the company found.

While not specifically cited here, an American Society for Testing & Materials diesel lubricity task force earlier raised questions about some acid-type lubricity improvers for negative interactions with other diesel additives and potential filter plugging (see Diesel Fuel News 12/10/01, p5). Refiners and pipelines considering a lubricity standard are especially worried about interactions of various additives in fungible diesel fuels

(see Diesel Fuel News 7/8/02, p5).