Master of Science, The Ohio State University, 2012, Mechanical Engineering

Reducing vehicle fuel consumption while maintaining same or better performance characteristics has been one of the main focuses of auto car manufacturers. In this sense, OEMs are introducing thermal management system (TMS) in modern vehicles that help attain rapid fluid warm-up during cold-start conditions. This leads to lower fluid viscosities early on in a drive cycle and hence reduced losses in the engine and powertrain components, resulting in lower fuel consumption. Rapid fluid warm-up also helps improve passenger comfort by providing necessary heating or cooling on demand. Through this work, a model characterizing the low frequency energy and power transfer in the engine and powertrain components is formulated. An advanced TMS consisting of components for waste heat energy recovery is proposed and its model is formulated. The combined set of these models is called the Vehicle Energy Simulator (VES). The model is thoroughly calibrated and validated using experimental data from steady state and transient testing; results are included in detail. The validated VES is then used to investigate control strategies for valves that are part of the TMS, used to control fluid flow to the various heat exchangers in order to attain rapid warm-up of coolant, engine oil and transmission fluid. It is seen that, the use of advanced TMS, over a conventional thermal management system, results in 3.4% reduction in fuel consumption. The investigation leads to recommendation of a reasonable first generation for a genetic algorithm optimization to be used to find the “optimal trajectory” for thermal-system-valve actuation during a drive cycle for reducing fuel consumption.

Committee: Marcello Canova PhD (Advisor); Giorgio Rizzoni PhD (Committee Member); Fabio Chiara PhD (Committee Member); Shawn Midlam-Mohler PhD (Committee Member) Subjects: Automotive Engineering; Engineering

Master of Science, The Ohio State University, 2020, Mechanical Engineering

The Ohio State EcoCAR team is a student project team at The Ohio State University providing real-world engineering experience and learning opportunities to engineering students. The EcoCAR Mobility Challenge is sponsored by the U.S. Department of Energy, General Motors, and The Mathworks and challenges twelve universities across the United States and Canada to redesign and reengineer a 2019 Chevrolet Blazer into a hybrid-electric vehicle. The goal of the competition is for students to develop and implement technologies to reduce the vehicle's environmental impact while maintaining performance and to enhance the vehicle with connected and automated technologies for a future in the mobility-as-a-service market. The transition from conventional to hybrid vehicle requires the addition of several hybrid powertrain components, including electric motors, power inverters, and a high voltage battery. These new components have thermal cooling requirements and require the integration of a dedicated thermal management system to prevent components from overheating and to maintain optimal operating temperature. This work models the thermal systems of the internal combustion engine and hybrid powertrain components to provide estimates for component temperatures during steady-state operation and predetermined drive cycles. The GT-Suite modeling software package from Gamma Technologies was chosen to model the two thermal systems because of its extensive library of pre-validated automotive grade component models. This library allowed component models to be built quickly and without extensive data collection. The thermal system models were integrated with a full-vehicle model of the OSU EcoCAR team's vehicle in Simulink. This work seeks to provide a reasonable approximation of the integrated thermal systems in the OSU EcoCAR vehicle, with provisions to update and calibrate the model in the future. The model provides both steady-state and drive cycle feedb (open full item for complete abstract)

Committee: Shawn Midlam-Mohler (Advisor); Giorgio Rizzoni (Committee Member) Subjects: Engineering; Mechanical Engineering

Master of Science, The Ohio State University, 2016, Mechanical Engineering

This research investigates the design and implementation of a light-duty truck's thermal management system control strategy developed from model-based techniques. To give robust durability and improve fuel economy, the control strategy must stabilize the dynamics of the engine operating temperatures, while also minimizing the energy consumed by the system. First, a detailed plant model is obtained by applying first principle physics (conservation laws) to model the thermal management system from its key components. The component models are combined to accurately predict the flow rates and temperatures of the system. The thermal system model is fed by a vehicle drivetrain mechanical model that calculates the heat rejection to the thermal model through a backward-looking approach. The nonlinear model is calibrated on supplier data and validated using experimental data recorded by a vehicle data acquisition system. Information from the engine control unit, flow rates, and temperatures were previously recorded for various driving profiles while the vehicle operated on a chassis dynamometer according to standard test procedure. The model accurately predicts the temperature dynamics of the system during transient operations of fully-warm drive cycles. Specifically, the Environmental Protection Agency's Federal Test Procedure for a highway drive cycle was used to test the model validity. The validated model provides a benchmark for comparing new controllers to the baseline thermal management control. Next, a model-based control strategy is developed to operate the thermal management system for tracking the desired fluid temperatures and limit the usage of the radiator fan, hence saving energy. In order to do so, the full system architecture was simplified using heat transfer analysis before utilizing an order-reduced, physical model that is linearized analytically. The reduced, linear plant models are then used to design a feedback controller by applying the Se (open full item for complete abstract)

Committee: Marcello Canova PhD (Advisor); Lisa Fiorentini PhD (Committee Member) Subjects: Automotive Engineering; Mechanical Engineering

Master of Science (M.S.), University of Dayton, 2022, Aerospace Engineering

Rotating Detonation Engines (RDEs) and pressure gain combustion (PGC) present a pathway to increased performance and fuel savings due to improved thermal efficiency and power density. RDEs utilize detonations to combust reactants, which provides higher thermal efficiencies than deflagration combustion. This increase in efficiency comes from increases in total pressure achieved across the detonation front, whereas deflagrations produce losses in total pressure. However, high thermal loads have limited uncooled and conventionally manufactured RDE test duration. Currently there is a need to develop novel cooling schemes that minimize the associated performance penalty, provide adequate cooling to extend test duration, and characterize changes in RDE performance and operability. This investigation was aimed at quantifying film cooling when applied to the unsteady and adverse pressure gradient of a RDE. Two film cooled outer-body combustion liners were manufactured and tested using a H2-air operated 6-inch RDE with an aerospike plug nozzle, heat sink center-body, and a 0.64 inch detonation channel width. Additionally, a control liner without holes was manufactured and tested. The two film cooled liners varied film pressure drop to characterize changes in RDE operability, temperature response, and cooling manifold pressure unsteadiness. All liners used approximately equivalent total flow area, as well as diameter weighted axial and circumferential spacing to allow comparison. The combustion air injection area ratio was set to 0.33, and the nozzle area ratio set to 1.0 and 0.66 relative to the channel area. Combustion air manifold pressures, cooling air manifold pressures, cooling air temperature, combustion liner temperature, operating mode, detonation stability, and detonation wave speed were analyzed for an array of combustion air mass flow rates, equivalence ratios, cooling air mass flow rates, and liner geometries. A high-speed camera was utilized to confirm operating (open full item for complete abstract)

Committee: Matthew Fotia (Committee Chair); Frederick Schauer (Committee Member); Adam Holley (Committee Member) Subjects: Aerospace Engineering; Mechanical Engineering