Improved Atomization of Methanol for Low-Temperature Starting in Spark-Ignition Engines

Heating neat (100 percent) methanol fuel (M100) is shown to improve dramatically the atomization of the fuel from a production, automotive, port fuel injector of pintle design. This improvement is particularly noticeable and important when compared with atomization at low fuel temperatures, corresponding to those conditions where cold-start is a significant problem with neat methanol-fueled (M100) vehicles. The improved atomization is demonstrated with photographs and laser-diffraction measurements of the drop-size distributions. Fuel temperatures were varied from -34°C (-29°F to 117°C (243°F), while the boiling point of methanol is 64.7°C (148.5°F). Air temperatures were ambient at about 24°C (75°F). For temperatures above the boiling point, some flash boiling and vaporization were presumably occurring, and these may have contributed to the atomization, but the trends for drop size did not shown any discontinuity near the boiling point. The possible application of this technology to solve the port-injected or throttle-body-injected, methanol-fueled, spark-ignition, low-temperature cold-start problem is discussed. Although the tests were conducted with neat methanol, the results might also be applicable to methanol-gasoline blends (e.g., M85), and the gasoline cold-start emissions problem.