DME for Green House Gas and Soot Emissions ReductionEPA Grant Number: SU839289
Title: DME for Green House Gas and Soot Emissions Reduction
Investigators: Boehmann, Andre
Institution: University of Michigan
EPA Project Officer: Page, Angela
Project Period: February 1, 2018 through January 31, 2019
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2017) RFA Text | Recipients Lists
Research Category: Sustainability , P3 Awards , P3 Challenge Area - Energy
Compression ignition (CI) engines play an important role in the transportation sector and many other sectors due to their high thermal efficiency (which results in lower green house gas (GHG) emission) as compared to spark ignition engines. However, the recent emission scandals including the Volkswagen scandal have cast doubts in the public whether the “clean diesel technology” can satisfy emissions standards for both criteria pollutants (e.g., NOx, soot) and GHG emissions. Unfortunately, future emission regulation is now demanding aggressive reduction in both the GHG and pollutant emission: EPA is about to implement a new federal pollutant emission standard, “Tier 3 emission standard”, and California Air Resource Board (CARB) will adopt a progressive carbon emission standard, “Assembly Bill 32”, in 3 years.
There is a need to develop innovative solutions to reduce both the GHG and pollutant emission at the same time. Adoption of a renewable, low carbon fuel for CI engines can enable both needs to be met. Dimethyl ether (DME) has received much attention as a diesel fuel substitute due to its high ignition quality, soot-free combustion character1, and non-toxicity. Furthermore, recent well-to-wheel life cycle assessment conducted by Oberon Fuels2 shows that if DME is produced through their proprietary Bio-DME process, such bio-DME can have a “negative” carbon intensity of -5gCO2/MJ (versus ULSD: +95gCO2/MJ). In spite of these advantages, adoption of DME in CI engines has been taken three decades due to the significantly different physical properties of DME compared to diesel fuels, such as low viscosity and low lubricity. The viscosity of DME is only about 1/12 of that of No.2 diesel fuel, resulting in unintended mechanical wear of the fuel injection system: excessive wear on injector and pump plunger, fuel leakage from injection pump. Also, it is difficult to increase the viscosity of DME by adding chemical species at traditional treat rates for fuel additives (e.g., 100’s or 1000’s of ppm). To overcome these challenges, we developed a blended fuel by mixing DME with other chemical species that are economically attractive and is expected to not undermine the advantages of DME as a clean alternative diesel fuel even at high blending ratio. We blended “glycerol”, a cheap by-product from the biodiesel production process that is anticipated to have soot-free emission character3, in mixtures with DME. The blend is experimentally proven to achieve the same viscosity as diesel fuel, resulting in the submission of an invention disclosure (U.S Provisional patent application number: 62/323,953).
The first objective of the current research project is ensuring that there is no mechanical malfunctioning in a CI engine and its fuel injection system with these DME-glycerol blends while enhancing the durability of the fuel supply system. Second, the overall ignition, combustion, and emissions character of the blend in CI engines will be investigated.
The investigation will be primarily experimental. Engine tests will be conducted with a Yanmar 3.7kW, single cylinder, diesel Genset (YDG 3700). Mechanical wear of the engine components will be checked by continuously running the engine for extended duration, as least as long as reported in the previous research that used neat DME. The depth and diameter of the wear scar on the fuel injector components will be measured and the measured data will, in turn, be used to quantify the durability of the mechanical components of the fuel supply system. Various ignition/combustion related parameters will be measured and be used for understanding the combustion process of the DME-glycerol blends in the CI engine. Emission analysis will be conducted by using gaseous and particulate emissions analyzers. The research is aimed at facilitating the adoption of DME in CI engines in order to satisfy the upcoming, stringent emission standards such as AB32 in California and the federal Tier 3 emissions standard. By creating a new market for glycerol, this research is also expected to provide incentives for the biodiesel companies to purify their waste-glycerine streams.
If the research can demonstrate that DME-glycerol blend can prevent the mechanical wear in the fuel injection system, it can directly benefit various sectors of society. The research can help engine companies developing CI engines for DME to reduce their time and cost used for research to re-design the fuel injection system to accommodate DME. It can also help DME producers to open markets to new customers. Eventually, these steps will help reduce carbon and pollutant emissions by exploiting the environmental benefits of DME. From an educational perspective, the combustion character of the DME-glycerol blends will yield new knowledge about the combustion character of glycerol.