Progress 07/01/18 to 02/29/20

Outputs
Target Audience:ClearFlame has not begun product deployment yet, as R&D is still ongoing, but the team is making good progress towards reaching the target audience. We are pivoting as a company from the "dual fuel fumigatation approach" considered in this USDA Phase I project to a full "ethanol only diesel engine" design. This design is even more relevant for this sector. After finding success in the agriculture sector, the technology can be extended to other Diesel engine applications, including transportation, power generation, mining, construction, marine, and rail. Of these, the heavy-duty transportation sector is likely the best target, since fuel costs are a significant pain point for those users, creating a market opportunity for ClearFlame's value proposition. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project taught the ClearFlame team how to better deliver value to the agriculture sector. The advantages to not needing ANY diesel fuel in our design are now apparent. How have the results been disseminated to communities of interest?Yes, although the company has pivoted to a single-fuel solution due to market interest. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? We were successful in implementing our technology and testing it on a chassis dynomameter without any emissions fault errors. In other words, but product could be used for mass production, although likely as a retrofit-only product. ClearFlame intends to stay more focused on technologies that can be deployed directly through OEM routes.

Publications

Progress 07/01/18 to 06/30/19

Outputs
Target Audience:ClearFlame has not begun product deployment yet, as R&D is still ongoing, but the team is making good progress towards reaching the target audience. ClearFlame will initially deploy this technology into the agriculture sector, given the synergy between farmers and ethanol production. The ClearFlame technology can save farmers money, and also allow them to use a fuel they help to produce, further improving profits by stimulating demand for corn. ClearFlame has been talking with potential farmers for pilot projects (likely in 2020), using either another Ram 3500 truck, or perhaps modifying the retrofit system for a different engine platform. Successful pilot demonstrations will enable large-scale distribution of the system through an agriculture distributor. After finding success in the agriculture sector, the technology can be extended to other Diesel engine applications, including transportation, power generation, mining, construction, marine, and rail. Of these, the heavy-duty transportation sector is likely the best target, since fuel costs are a significant pain point for those users, creating a market opportunity for ClearFlame's value proposition. Changes/Problems:Initial chassis dyno testing demonstrated key attributes of ethanol substitution when integrated into a production engine. Chassis dyno testing enables simultaneous measurement of engine-out emissions (the pre-catalyst emissions levels right as the exhaust leaves the manifold) and tailpipe-out emissions (the post-catalyst emissions levels leaving the vehicle). The first observation was that engine-out NOx emissions were relatively unchanged, but tailpipe-out emissions were significantly elevated for high levels of ethanol substitution. These results indicate that the high ethanol substitution level is causing enough failure in the existing engine aftertreatment that the vehicle would fail an emissions test, which runs afoul of EPA modification rules. Thus, this indicates that the system will need to be limited to a relatively low ethanol substitution (less than ~33%) to remain in compliance with EPA rules. ClearFlame has been able to stay on track regarding budget, although progress has been somewhat slower than initially expected. This was largely the result of the challenging requirements for field testing on the Ram 3500 truck. While ClearFlame did conduct an initial baseline test on a chassis dynamometer at MAHLE Powertrain (allowing careful control of the engine load), the vast majority of testing was conducted during regular road driving. Given that city driving can vary significantly between trips, ClearFlame focused on longer drives to compare system results (given that average operating conditions were more consistent across longer trips). While this strategy yielded better experimental results, it did increase the time between test drives, lengthening the project timeline. Seasonal weather variations also presented challenges for ClearFlame as we designed our system. Many of the factors that limit the ethanol substitution ratio--such as the point at which evaporative charge cooling leads to Diesel misfire--are functions of ambient air temperature, which changes significantly throughout the seasons in the Chicago area (and in most of the farm belt). This means that many tests can only be conducted during the summer, or winter. For example, ClearFlame first discovered the challenge of misfire limits in late March 2018, but the team was not able to adequately test our planned engineering solutions until temperatures cooled again in late fall 2018. Environmental vehicle test chambers can be used to control the engine environment, but use of such facilities would be prohibitively expensive for this project. There has also been some delay due to competition for engine test cell time within Argonne National Laboratory. The SCOTE test engine used for this project is also committed to other projects, so ClearFlame can only operate the SCOTE in its dual-fuel configuration a fraction of the time. Furthermore, the engine test cell that contains the SCOTE also contains another engine, and the two engines cannot be run at the same time. This has limited the test time available, but the work will still be completed in a timely manner. What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?ClearFlame has been sharing the results of our early testing with farmers throughout the Midwest, as we prepare for pilot demonstrations in 2020. What do you plan to do during the next reporting period to accomplish the goals?In the near future, ClearFlame is also looking to integrate real-time emissions measurements using a Semtech-DS mobile exhaust measuring system (made by Sensors, Inc.). This system is currently being installed on the RAM 3500 truck, and will enable ClearFlame to have accurate, real-time emissions data during system operation without expensive chassis dyno testing. This is essential, as it will allow ClearFlame to determine if the retrofit system is remaining in compliance with EPA rules during system testing and tuning, as the design evolves. Before the end of this Phase I project, ClearFlame hopes to perform another round of chassis dynamometer testing, to get very accurate measurements of fuel consumption and emissions levels once the alpha prototype system optimization is complete. This work will include engine oil testing to check for excessive penetration of ethanol into the engine oil. This is one of ClearFlame greatest concerns for the long-term durability of our system. ClearFlame has already confirmed that low ethanol substitution levels do not interfere with the engine combustion and catalyst operation, but tainted oil is one of the few untested pathways for harming the engine. Engineers at lubricant testing and supply companies have theorized that ethanol's high vapor pressure makes it likely to evaporate out of engine oil at steady engine operating temperatures, to be drawn into the intake air from the crank case vent. However, ClearFlame has been periodically taking oil samples from both the SCOTE and the truck, to be tested by a third party at a later date to verify this theory.

Impacts
What was accomplished under these goals? ClearFlame researchers outfitted a single cylinder heavy duty research engine with an ethanol-compatible port fuel injector to collect data on the dual-fuel combustion concept in a controlled environment. The single cylinder engine (the "SCOTE") is equipped with an in-cylinder pressure transducer, thermocouples to measure temperatures, and an exhaust emissions analyzer. The intake air temperature and pressure can be controlled, as can the exhaust back-pressure, to simulate the turbocharged conditions of a multi-cylinder Diesel engine. The data were collected at steady state at 1500rpm, with 5psig intake and exhaust pressures, and warm intake air (simulating turbocharging). For higher load points, the LHV efficiency of dual-fuel combustion is comparable to, or higher than, the baseline Diesel, whereas for lower loads the dual fuel efficiency drops below that of Diesel. The emissions measurements in this case (not shown) shed light on the underlying reason for falling efficiency at low loads, as they point to incomplete combustion of fuel, most likely the ethanol. It is likely that the ethanol/air mixture is too dilute at very low loads to be fully ignited, and any regions not in close contact with the Diesel injection might not fully react. For this reason, the dual fuel system has been designed by ClearFlame to shut off ethanol fueling for low loads, returning the engine to standard Diesel configuration. This allows the system to operate at high efficiency points, combining the best of the different curves for each engine load. In addition to efficiency benefits, the results of dual fuel investigation reveal lower engine-out NOx emissions as well. This could reduce the required dosing of DEF in the engine's SCR system, potentially lowering costs or extending maintenance intervals for the SCR. Further testing of this effect on a production engine with integrated SCR system (like the ClearFlame work truck) will reveal if the anticipated benefit of low engine-out NOx translates to lighter catalyst loading. One area requiring close attention in the optimizing of the dual-fuel system is the engine's soot emissions, which have been challenging in some previous dual-fuel efforts. Under certain conditions, soot emissions for dual fuel combustion are higher than they are for pure Diesel combustion (whereas they are lower for other conditions). The exhaust temperature for the 22% ethanol case is nearly 50°C lower than the pure Diesel case at the same load. Lower temperatures at high load can be very beneficial to longevity of components such as exhaust valves and turbochargers,but if temperatures drop too low at lower loads they can interfere with regeneration of theparticulate filter or operation of the SCR (these results were both observed in later experiments using ClearFlame's work truck). For this reason, in optimizing the dual fuel system, ClearFlame is paying close attention to soot formation and exhaust temperature to ensure proper particulate filter and SCR cycling is maintained. ClearFlame manufactured our ethanol substitution system by integrating stock gasoline/ethanol injectors into the intake elbow of the RAM 3500 truck (with a Cummins 6.7L Diesel engine). An ethanol fuel tank was installed into the truck bed, and fuel lines were routed underneath the vehicle into the engine compartment. The fuel was heated prior to injection via heat exchange with the engine coolant, and fuel flow was regulated with a series of solenoids and check valves (in addition to the injectors). Control of the substitution system was enabled by using a custom PCB board, a stock Arduino controller, and a custom ClearFlame control algorithm (in C++). Engine data was acquired by the system via the truck's existing OBD port and communication protocols. Approximately five times a second, the controller requests engine speed/load data from the vehicle, and makes a calculation of the required substitution ratio based on the inputs (ClearFlame used the results from the SCOTE experiment to better estimate what the ideal substitution fraction should be). This substitution ratio was used to generate an injector firing signal and pump command that were sent to the engine hardware, while also regulating fuel flow with the solenoids. ClearFlame has also conducted on road testing to measure system performance. Initially, this testing has focused on measuring fuel economy. Real-time fuel flow rate data are available from the OBD system, although the accuracy of those data are not well known. To help validate the data, ClearFlame summed the fuel consumption values over a long period of time, and compared the result to the amount of fuel drained from the fuel tank over the same interval. This latter quantity could be determined by filling the tank at a retail station, driving for an extended period of time, and then measuring the quantity of fuel delivered from the pump at the same station when refueling the tank. This measurement method was not particularly accurate either, but when compared to the other measurement technique, the results agreed to within ~3%, giving ClearFlame confidence in the fuel consumption numbers. These results indicate the benefits of using ethanol fuel, even at the relatively low substitution fractions allowed by the SCR system. The results only show a ~4% improvement in fuel costs--the result of using low-cost ethanol in an efficient manner--but this was achieved with relatively little optimization. More research on the SCOTE will allow for even greater improvements, which will drive ClearFlame's reduced fuel cost value proposition to greater levels. That said, even this level of improvement is likely adequate, giving the long payback periods tolerated by farmers (a result of the long equipment lifetimes).

Publications

Progress 07/01/18 to 02/28/19

Outputs
Target Audience:ClearFlame has not begun product deployment yet, as R&D is still ongoing, but the team is making good progress towards reaching the target audience. ClearFlame will initially deploy this technology into the agriculture sector, given the synergy between farmers and ethanol production. The ClearFlame technology can save farmers money, and also allow them to use a fuel they help to produce, further improving profits by stimulating demand for corn. ClearFlame has been talking with potential farmers for pilot projects (likely in 2020), using either another Ram 3500 truck, or perhaps modifying the retrofit system for a different engine platform. Successful pilot demonstrations will enable large-scale distribution of the system through an agriculture distributor. After finding success in the agriculture sector, the technology can be extended to other Diesel engine applications, including transportation, power generation, mining, construction, marine, and rail. Of these, the heavy-duty transportation sector is likely the best target, since fuel costs are a significant pain point for those users, creating a market opportunity for ClearFlame's value proposition. Changes/Problems:Initial chassis dyno testing demonstrated key attributes of ethanol substitution when integrated into a production engine. Chassis dyno testing enables simultaneous measurement of engine-out emissions (the pre-catalyst emissions levels right as the exhaust leaves the manifold) and tailpipe-out emissions (the post-catalyst emissions levels leaving the vehicle). The first observation was that engine-out NOx emissions were relatively unchanged, but tailpipe-out emissions were significantly elevated for high levels of ethanol substitution. These results indicate that the high ethanol substitution level is causing enough failure in the existing engine aftertreatment that the vehicle would fail an emissions test, which runs afoul of EPA modification rules. Thus, this indicates that the system will need to be limited to a relatively low ethanol substitution (less than ~33%) to remain in compliance with EPA rules. ClearFlame has been able to stay on track regarding budget, although progress has been somewhat slower than initially expected. This was largely the result of the challenging requirements for field testing on the Ram 3500 truck. While ClearFlame did conduct an initial baseline test on a chassis dynamometer at MAHLE Powertrain (allowing careful control of the engine load), the vast majority of testing was conducted during regular road driving. Given that city driving can vary significantly between trips, ClearFlame focused on longer drives to compare system results (given that average operating conditions were more consistent across longer trips). While this strategy yielded better experimental results, it did increase the time between test drives, lengthening the project timeline. Seasonal weather variations also presented challenges for ClearFlame as we designed our system. Many of the factors that limit the ethanol substitution ratio--such as the point at which evaporative charge cooling leads to Diesel misfire--are functions of ambient air temperature, which changes significantly throughout the seasons in the Chicago area (and in most of the farm belt). This means that many tests can only be conducted during the summer, or winter. For example, ClearFlame first discovered the challenge of misfire limits in late March 2018, but the team was not able to adequately test our planned engineering solutions until temperatures cooled again in late fall 2018. Environmental vehicle test chambers can be used to control the engine environment, but use of such facilities would be prohibitively expensive for this project. There has also been some delay due to competition for engine test cell time within Argonne National Laboratory. The SCOTE test engine used for this project is also committed to other projects, so ClearFlame can only operate the SCOTE in its dual-fuel configuration a fraction of the time. Furthermore, the engine test cell that contains the SCOTE also contains another engine, and the two engines cannot be run at the same time. This has limited the test time available, but the work will still be completed in a timely manner. What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?ClearFlame has been sharing the results of our early testing with farmers throughout the Midwest, as we prepare for pilot demonstrations in 2020. What do you plan to do during the next reporting period to accomplish the goals?In the near future, ClearFlame is also looking to integrate real-time emissions measurements using a Semtech-DS mobile exhaust measuring system (made by Sensors, Inc.). This system is currently being installed on the RAM 3500 truck, and will enable ClearFlame to have accurate, real-time emissions data during system operation without expensive chassis dyno testing. This is essential, as it will allow ClearFlame to determine if the retrofit system is remaining in compliance with EPA rules during system testing and tuning, as the design evolves. Before the end of this Phase I project, ClearFlame hopes to perform another round of chassis dynamometer testing, to get very accurate measurements of fuel consumption and emissions levels once the alpha prototype system optimization is complete. This work will include engine oil testing to check for excessive penetration of ethanol into the engine oil. This is one of ClearFlame greatest concerns for the long-term durability of our system. ClearFlame has already confirmed that low ethanol substitution levels do not interfere with the engine combustion and catalyst operation, but tainted oil is one of the few untested pathways for harming the engine. Engineers at lubricant testing and supply companies have theorized that ethanol's high vapor pressure makes it likely to evaporate out of engine oil at steady engine operating temperatures, to be drawn into the intake air from the crank case vent. However, ClearFlame has been periodically taking oil samples from both the SCOTE and the truck, to be tested by a third party at a later date to verify this theory.

Impacts
What was accomplished under these goals? ClearFlame researchers outfitted a single cylinder heavy duty research engine with an ethanol-compatible port fuel injector to collect data on the dual-fuel combustion concept in a controlled environment. The single cylinder engine (the "SCOTE") is equipped with an in-cylinder pressure transducer, thermocouples to measure temperatures, and an exhaust emissions analyzer. The intake air temperature and pressure can be controlled, as can the exhaust back-pressure, to simulate the turbocharged conditions of a multi-cylinder Diesel engine. The data were collected at steady state at 1500rpm, with 5psig intake and exhaust pressures, and warm intake air (simulating turbocharging). For higher load points, the LHV efficiency of dual-fuel combustion is comparable to, or higher than, the baseline Diesel, whereas for lower loads the dual fuel efficiency drops below that of Diesel. The emissions measurements in this case (not shown) shed light on the underlying reason for falling efficiency at low loads, as they point to incomplete combustion of fuel, most likely the ethanol. It is likely that the ethanol/air mixture is too dilute at very low loads to be fully ignited, and any regions not in close contact with the Diesel injection might not fully react. For this reason, the dual fuel system has been designed by ClearFlame to shut off ethanol fueling for low loads, returning the engine to standard Diesel configuration. This allows the system to operate at high efficiency points, combining the best of the different curves for each engine load. In addition to efficiency benefits, the results of dual fuel investigation reveal lower engine-out NOx emissions as well. This could reduce the required dosing of DEF in the engine's SCR system, potentially lowering costs or extending maintenance intervals for the SCR. Further testing of this effect on a production engine with integrated SCR system (like the ClearFlame work truck) will reveal if the anticipated benefit of low engine-out NOx translates to lighter catalyst loading. One area requiring close attention in the optimizing of the dual-fuel system is the engine's soot emissions, which have been challenging in some previous dual-fuel efforts. Under certain conditions, soot emissions for dual fuel combustion are higher than they are for pure Diesel combustion (whereas they are lower for other conditions). The exhaust temperature for the 22% ethanol case is nearly 50°C lower than the pure Diesel case at the same load. Lower temperatures at high load can be very beneficial to longevity of components such as exhaust valves and turbochargers,but if temperatures drop too low at lower loads they can interfere with regeneration of theparticulate filter or operation of the SCR (these results were both observed in later experiments using ClearFlame's work truck). For this reason, in optimizing the dual fuel system, ClearFlame is paying close attention to soot formation and exhaust temperature to ensure proper particulate filter and SCR cycling is maintained. ClearFlame manufactured our ethanol substitution system by integrating stock gasoline/ethanol injectors into the intake elbow of the RAM 3500 truck (with a Cummins 6.7L Diesel engine). An ethanol fuel tank was installed into the truck bed, and fuel lines were routed underneath the vehicle into the engine compartment. The fuel was heated prior to injection via heat exchange with the engine coolant, and fuel flow was regulated with a series of solenoids and check valves (in addition to the injectors). Control of the substitution system was enabled by using a custom PCB board, a stock Arduino controller, and a custom ClearFlame control algorithm (in C++). Engine data was acquired by the system via the truck's existing OBD port and communication protocols. Approximately five times a second, the controller requests engine speed/load data from the vehicle, and makes a calculation of the required substitution ratio based on the inputs (ClearFlame used the results from the SCOTE experiment to better estimate what the ideal substitution fraction should be). This substitution ratio was used to generate an injector firing signal and pump command that were sent to the engine hardware, while also regulating fuel flow with the solenoids. ClearFlame has also conducted on road testing to measure system performance. Initially, this testing has focused on measuring fuel economy. Real-time fuel flow rate data are available from the OBD system, although the accuracy of those data are not well known. To help validate the data, ClearFlame summed the fuel consumption values over a long period of time, and compared the result to the amount of fuel drained from the fuel tank over the same interval. This latter quantity could be determined by filling the tank at a retail station, driving for an extended period of time, and then measuring the quantity of fuel delivered from the pump at the same station when refueling the tank. This measurement method was not particularly accurate either, but when compared to the other measurement technique, the results agreed to within ~3%, giving ClearFlame confidence in the fuel consumption numbers. These results indicate the benefits of using ethanol fuel, even at the relatively low substitution fractions allowed by the SCR system. The results only show a ~4% improvement in fuel costs--the result of using low-cost ethanol in an efficient manner--but this was achieved with relatively little optimization. More research on the SCOTE will allow for even greater improvements, which will drive ClearFlame's reduced fuel cost value proposition to greater levels. That said, even this level of improvement is likely adequate, giving the long payback periods tolerated by farmers (a result of the long equipment lifetimes).

Publications