Design, Implementation and Testing of a Hydrogen-Assisted Combustion System for a Light Duty Diesel Vehicle
Open Access
- Author:
- Shirk, Matthew Glenn
- Graduate Program:
- Mechanical Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- None
- Committee Members:
- Daniel Connell Haworth, Thesis Advisor/Co-Advisor
- Keywords:
- hydrogen diesel
dual-fuel
hydrogen
diesel
challenge x - Abstract:
- Two experiments were conducted to investigate the effects and feasibility of the addition of gaseous hydrogen to the intake air of two similar, production compression-ignition (CI) engines fueled primarily with a biodiesel fuel blend. In the first experiment, a 1.3L, 52 kW CI engine coupled to an eddy-current dynamometer was tested at eight steady-state operating modes of fixed speed and load. The operating points for steady-state dynamometer testing were chosen based on those most prevalent in a computer-simulated urban drive cycle. The drive cycle was simulated in the Matlab-based Powertrain Systems Analytical Toolkit (PSAT) program using the specifications of the engine to be tested along with those of a 2005 Chevrolet Equinox that has been modified for further testing of a hydrogen-assisted diesel combustion system. During the tests, data were collected on engine operating parameters, fuel consumption, and the concentration of total oxides of nitrogen (NOX) in the exhaust stream. Each steady-state point was baseline tested, without the addition of hydrogen to the intake air. Each mode was then tested with hydrogen being fumigated into the intake air at flow rates equivalent to both five and ten percent of the total fuel energy flow into the engine. For the second experiment, the drivetrain of a 2005 Chevrolet Equinox was stripped was removed and replaced with a 1.3L, 67kW CI engine, an improved version of the engine used in the first experiment. The engine was mated to a five-speed automatic transmission utilizing a modified torque converter calibrated for the CI engine and vehicle mass. A gaseous hydrogen storage system was installed in the vehicle along with fueling, fuel delivery, leak detection, and hydrogen fuel injection systems developed as part of this experiment. The gaseous fuel injector used to deliver hydrogen to the engine intake was calibrated to correlate hydrogen flow rate to duty cycle, and a control strategy was developed to inject the hydrogen as a function of real-time diesel fuel energy flow into the engine. The fuel injection system was controlled by code embedded in a master vehicle controller (MVC) via the vehicle’s controller area network (CAN) bus. After months of extensive road and track testing of the vehicle operating in the hydrogen-assisted combustion mode, chassis dynamometer testing was used to run repeatable drive cycles while logging data. On the dynamometer, the vehicle was operated through a portion of the urban drive cycle simulated for the first experiment, while engine data were logged along with diesel and hydrogen fuel flows, and temperature and NOX concentration of the exhaust stream. The drive cycle was repeated, with different hydrogen quantities commanded, and the same data were logged. NOX emissions and engine data recorded during the baseline testing were compared with those results obtained while injecting hydrogen during the drive cycles. The results of the experiments indicated a slight rise in exhaust temperatures, little change in NOX concentration, and minimal changes in efficiency as the engine was operated with five and ten percent hydrogen during steady state and cycle testing. An increase in thermal NOX was expected due to elevated exhaust temperature, along with slightly lower efficiency due to the increased premixed combustion of the pilot injection and hydrogen mixture before top dead center. This effect was expected to be exacerbated by the decrease in the amount of working fluid in the cylinder, as air was displaced by aspirated hydrogen. The onboard dual-fuel hydrogen-biodiesel system was shown to be feasible through operation, both during dynamometer and road testing.