Master of Science, The Ohio State University, 2013, Mechanical Engineering

Rising fuel prices and tightening vehicle emission regulations have led to a large demand for fuel efficient passenger vehicles. Among several design improvements and technical solutions, advanced Thermal Management Systems (TMS) have been recently developed to more efficiently manage the thermal loads produced by internal combustion engines and thereby reduce fuel consumption. Advanced TMS include complex networks of coolant, oil and transmission fluid lines, heat exchangers, recuperators, variable speed pumps and fans, as well as active fluid flow control devices that allows for a greatly improved freedom to manage the heat rejection and thermal management of the engine and transmission components. This control authority can be exploited, for instance, to rapidly warm the powertrain fluids during vehicle cold-starts, and then maintain them at elevated temperatures. Increasing the temperatures of the engine oil and transmission fluid decreases their viscosity, ultimately leading to a reduction of the engine and transmission frictional losses, and improved fuel economy. On the other hand, robust and accurate TMS controllers must be developed in order to take full advantage of the additional degrees of freedom provided by the available actuators and system hardware configuration. To this extent, this work focuses on developing model-based TMS controls for a prototype light-duty automotive powertrain during fully warmed-up vehicle operation. The design of the models and control algorithms is conducted in parallel with the development of a prototype TMS, hence realizing a co-design of the TMS hardware and control system. In order to achieve this goal, first-principle models are created to characterize the thermal dynamics of the TMS components, and calibrated on specific components' data. The submodels are then integrated into a complete TMS model predicting the temperature dynamics of the powertrain fluids in response to commands to the available syst (open full item for complete abstract)

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

Master of Science in Mechanical Engineering (MSME), Wright State University, 2023, Mechanical Engineering

This work is investigating a dual mode Rankine cycle for aircraft applications, specifically meeting vehicle thermal and power requirements. This multiconfigurational approach allows the Thermal Management System (TMS) to be controlled based on aircraft needs. In this design, waste heat is removed from critical areas of the aircraft (e.g., propulsion, structure, subsystems) using the fuel as a heat sink. Hot fuel is then forced through a heat exchanger actively boiling water. The vapor byproduct is fed to a turbine coupled to a generator, providing power. The low-pressure steam is then condensed using cold fuel drawn from its tank; however, when additional cooling is needed, this steam is exhausted instead. Methods used are a blend of empirical and theoretical studies where a small-scale experimental rig is used to validate component models. MATLAB/Simulink software is used to capture their individual performance within the steady state and transient reschemes. With model fidelity established, scaling is used to assess the feasibility of the dual mode Rankine cycle. Using steady state results accuracy of modeled components was assessed based on root-mean-squared-error (RMSE). The single-phase heat exchanger showed the least error at 0.8%. Tube-in-tube and corrugated plate evaporators resulted in an RMSE of 14.2% and 1.0%, respectively. Evaporator transients were also analyzed, and predicted time constants led the experimental results showing a mean error of 13.8%, for the tube-in-tube evaporator and 82% for the corrugated plate evaporator. The scroll expanders performance represented the power capabilities of the system. Model results showed a RMSE of 10.1% and second law efficiency RMSE of 0.15%. With increased confidence in component models, a vehicle scaling was performed predicting system performance during two operating modes . During high-heat mode, thermal efficiency was 6.51% and second law efficiencies was 63.7%. During reduced-heat mode, thermal efficien (open full item for complete abstract)

Committee: Mitch Wolff Ph.D. (Advisor); Abdeel Roman Ph.D. (Committee Member); Jose Camberos Ph.D., P.E. (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy (PhD), Wright State University, 2023, Engineering PhD

Icing, or the formation of ice from water via freezing or water vapor via desublimation, is a phenomenon that commonly occurs within air cycle-based refrigeration systems and requires thermal control that limits system performance. In aircraft applications icing frequently occurs in the heat exchangers and turbine(s) that are part of the air cycle machine, the refrigeration unit of the environmental control system. Traditionally, water vapor is removed from an air cycle machine via condensing in a heat exchanger and subsequent high-pressure water separation. This approach is not capable of removing all of the vapor present at low altitude conditions, corresponding to a high risk of icing. To mitigate icing under these conditions, a membrane dehumidifier is considered to separate the water vapor that remains after condensing and liquid water separation. Three distinct investigations are conducted as part of this work. The first is aimed at modeling approaches for desublimation frosting, or frost growth on sufficiently cold flat surfaces. This results in a novel, analytical, and non-restrictive solution well-suited for representing frost growth and densification in moist air heat exchangers. The second investigation concerns membrane dehumidification and module design. A custom component model is developed and verified under aircraft conditions, then the Pareto frontier of volumetrically efficient membrane modules is characterized via a multi-objective optimization study. The final investigation evaluates three two-wheel air cycle subsystem architectures with differing dehumidification approaches: (1) condenser-based, (2) membrane dehumidifier-based, and (3) combined. Steady-state simulations are run for each of these over a range of flow rates and altitudes. The results demonstrate that incorporating a membrane dehumidifier reduces the turbine inlet saturation temperature, which mitigates icing in the turbine and reduces the required bypass fl (open full item for complete abstract)

Committee: Mitch Wolff Ph.D. (Advisor); James Menart Ph.D. (Committee Member); Abdeel Roman Ph.D. (Committee Member); José Camberos Ph.D., P.E. (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2022, Mechanical Engineering

Global regulatory targets for reducing CO2 emissions along with the customer demand is driving the automotive sector towards energy efficient transportation. Powertrain electrification offers great potential to improve the fuel economy due to the extra control flexibility compared to vehicles with a single power source. The benefits of the electrification can be significantly reduced when auxiliaries such as the vehicle climate control system directly competes with the powertrain for battery energy, reducing the range and energy efficiency. Connected and Automated Vehicles (CAVs) can increase the energy savings by allowing to switch from instantaneous optimization to predictive optimization by leveraging information from advanced navigation systems, Vehicle-to-Infrastructure (V2I) and Vehicle-to-Vehicle (V2V) communication. In this work, two energy optimization problems for CAVs are studied. First is to jointly optimize the vehicle and powertrain dynamics and the second is to optimize the vehicle climate control system. The focus of this work is to combine the Dynamic Programming (DP), Approximate Dynamic Programming (ADP) and perturbation theory based approaches to solve the energy optimization problems with variations in external inputs and parameters that affects the plant model, objective function or constraints. To this end, mathematical methods are used to develop two novel algorithms that compensates for mismatches between nominal and estimated parameters. The first approach develops a cost correction scheme to evaluate the sensitivity of the value function to parameters, with the ultimate goal of correcting the original optimization problem online with the observed parameters. Two case-studies are considered with variations in vehicle payload and auxiliary power load. Second, a novel algorithm for solving dynamic optimization problem is developed to apply closed-loop corrections to solution of the original optimization problem without the need to (open full item for complete abstract)

Committee: Marcello Canova (Advisor); Abhishek Gupta (Committee Member); Stephanie Stockar (Committee Member) Subjects: Engineering; Mechanical Engineering

Doctor of Philosophy (PhD), Wright State University, 2022, Engineering PhD

High-power laser systems (HPLS) have wide-ranging applications in many prominent areas. HPLS use laser diodes to pump fiber gain media. Understanding the functionality of both components is critical for achieving effective HPLS operation. System optical efficiency is a function of diode junction temperature. As junction temperature changes, the wavelength spectrum of the diode output shifts causing optical power losses in the fiber gain media. Optical/thermal interactions of the dynamically coupled laser diodes and fiber gain media are not fully understood. A system level modeling approach considering the interactions between optical performance and component temperature is necessary. Four distinct models were created: Diode optical, diode thermal, fiber optical, and fiber thermal. Dynamically coupling these models together provided the capability to demonstrate how HPLS electro-to-optical efficiency changes when the laser diode pump spectrum shifts due to various levels of thermal management. Subsequent studies were done to determine which parameters across all four models had the most significant impact on laser performance from a designer's perspective. Next, a statistical surrogate model was created by varying these parameters to create a parameter space. Response variables of interest were then reduced to a single equation as a function of these important parameters across the parameter space, allowing for quicker exploration of the potential design space. Lastly, laser time to steady state and laser efficiency were employed to determine when a specific diode cooling method should be used to achieve the highest laser efficiency. Understanding the optical/thermal interactions of laser operation and exploring the impact of various thermal capabilities can provide better system design and optimization guidelines. Bridging the gap between the optical and thermal aspects of laser operation in pursuit of such understanding has been made possible by the re (open full item for complete abstract)

Committee: Rory Roberts Ph.D. (Advisor); Mitch Wolff Ph.D. (Committee Member); George Huang Ph.D. (Committee Member); Amir Farajian Ph.D. (Committee Member); Soumya Patnaik Ph.D. (Committee Member) Subjects: Mechanical Engineering; Optics

Master of Science in Mechanical Engineering (MSME), Wright State University, 2021, Mechanical Engineering

Two sub-systems that present a significant challenge in the development of highperformance air vehicle exceeding speeds of Mach 5 are the power generation and thermal management sub-systems. The air friction experienced at high speeds, particularly around the engine, generates large thermal loads that need to be managed. In addition, traditional jet engines do not operate at speeds greater than Mach 3, therefore eliminating the possibility of a rotating power generator. A multi-mode water-based Rankine cycle is an innovative method to address both of these constraints of generating power and providing cooling. Implementing a Rankine cycle-based system allows for the waste heat from the vehicle to be used to meet the onboard power requirements. This application of a Rankine cycle differs from standard power plant applications because the transient system dynamics become important due to rapid changes in thermal loads and electrical power requirements. Both an experimental and computational investigation is presented. An experimental steady state energy balance was used to determine a 5.1% and 11.5% thermal and Second Law efficiency, respectively. Transient testing showed an increase in power generation of 283% in 30.5 seconds when starting from idle, with a steady state power generation of 230 W. In addition to the power generation, the experimental system removed 10.7 kW from the hot oil loop which emulates a typical aircraft cooling fluid. Experimental results were used in the development of dynamic computational models using OpenModelica, an opensource modeling tool. Deviation between model and experimental results was within 5% for component models and 3.5% when analyzing the system energy balance. Testing of the vehicle level model included steady state, transient, and simulated mission, which was used to characterize performance and develop the system controls. During transient testing, the system controls demonstrated the ability to meet b (open full item for complete abstract)

Committee: Mitch Wolff Ph.D. (Advisor); Rory Roberts Ph.D. (Committee Member); José Camberos Ph.D. (Committee Member); Levi Elston M.S. (Other) Subjects: Mechanical 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 in Mechanical Engineering (MSME), Wright State University, 2018, Mechanical Engineering

As technology advances, the abilities of civilian and military vehicles, both air and ground, will undoubtedly increase as well. One of the main areas of improvement is in the electronics area. The new electronics are ever smaller, use ever higher amounts of electrical power, and require ever smaller temperature tolerances. This leads to the problem of effectively managing the increasing thermal loads and temperature tolerances on these systems. One electronic system that causes concern is a high energy pulse system (HEPS). These devices have very high thermal loads (100s of kW). On an air vehicle, where thermal management by legacy methods (i.e. fuel as the heat sink) is already problematic, a HEPS will certainly overload the thermal management system (TMS). HEPS performance must be understood and quantified more accurately to understand the design requirements of a TMS for this device. To aid in this understanding, the HEPS itself and a palletized system to thermally manage the HEPS will be modeled. Previous analysis of a cryogenic palletized HEPS contained a simplified power model for a HEPS that had a set efficiency and always gave a certain amount of optical power out and a certain amount of power dissipated as heat based on that set efficiency. The HEPS model developed and presented takes into account the temperature of internal HEPS components and changes the efficiency accordingly. The HEPS efficiency changes with component temperature to provide a better understanding of the consequences of not thermally managing a HEPS effectively. Along with the HEPS model, a cryogenic-based palletized TMS using Liquefied Natural Gas (LNG) for indirectly cooling the HEPS was modeled. Using LNG as a method of cooling is a possible alternative to using very large legacy systems (fuel as heat sink) to cool a HEPS. The architecture of this palletized system uses LNG to cool the heat loads. The LNG then becomes the fuel for the turbo-generator, which produces electrical po (open full item for complete abstract)

Committee: Rory Roberts Ph.D. (Advisor); Mitch Wolff Ph.D. (Committee Member); Zifeng Yang Ph.D. (Committee Member) Subjects: Aerospace Engineering; 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

MS, University of Cincinnati, 2014, Engineering and Applied Science: Mechanical Engineering

This thesis describes a novel system that is being developed that utilizes latent thermal energy storage (LTES) to shift residential heating and cooling loads, between 2-4 hr. time periods, away from the electrical power grid (during the utilities' peak demand period) for the main purpose of residential demand-side-management. More and more utilities are now offering residential time-of-day rates (and load interrupt programs) to help improve their load factor as a means to curtail the building of new power generating stations, and will only increase in time with greater implementation and the enabling use of smart meters. TES is ideally suited to capitalize on this fact and stands ready in this proposed new system; running the HVAC equipment during the time of excess system capacity and storing the “hot or cold energy created” in the PCM for later use during the peak system demand period will improve the system's load. This thesis describes the proposed system and the equipment layout along with its operating strategy. In addition to being modular in design and thus allowing for all different size homes, another major key feature of the proposed system is that it is of the “plug-in” type which utilizes the current cooling and heating hardware of the existing home, and as such, is equally applicable to new home construction or retrofits. This thesis also presents the economics of the system and potential benefits to the home owner, more specifically, simple calculations are given showing the estimated monthly operating cost savings when using this TES system with residential time-of-day (TD) rates, over that of the home operating without TES and running on the standard residential service (RS) rate structure. This thesis document provides the detailed mathematical formulation for the solution of planar moving boundary problems using enhanced enthalpy method with given fixed temperature and insulated boundary conditions. The solution methodology and results, obt (open full item for complete abstract)

Committee: Michael Kazmierczak Ph.D. (Committee Chair); Ahmed Elgafy Ph.D. (Committee Member); Frank Gerner Ph.D. (Committee Member) Subjects: Mechanics

PhD, University of Cincinnati, 2014, Engineering and Applied Science: Aerospace Engineering

Current industry trends demonstrate aircraft electrification will be part of future platforms in order to achieve higher levels of efficiency in various vehicle level sub-systems. However electrification requires a substantial change in aircraft design that is not suitable for re-winged or re-engined applications as some aircraft manufacturers are opting for today. Thermal limits arise as engine cores progressively get smaller and hotter to improve overall engine efficiency[8], while legacy systems still demand a substantial amount of pneumatic, hydraulic and electric power extraction. The environmental control system (ECS) provides pressurization, ventilation and air conditioning in commercial aircraft[7], making it the main heat sink for all aircraft loads with exception of the engine. To mitigate the architecture thermal limits in an efficient manner, the form in which the ECS interacts with the engine will have to be enhanced as to reduce the overall energy consumed and achieve an energy optimized solution. This study examines a tradeoff analysis of an electric ECS by use of a fully integrated Numerical Propulsion Simulation System (NPSS) model that is capable of studying the interaction between the ECS and the engine cycle deck. It was found that a peak solution lays in a hybrid ECS where it utilizes the correct balance between a traditional pneumatic and a fully electric system. This intermediate architecture offers a substantial improvement in aircraft fuel consumptions due to a reduced amount of waste heat and customer bleed in exchange for partial electrification of the air-conditions pack which is a viable option for re-winged applications.

Committee: Awatef Hamed Ph.D. (Committee Chair); Neil Garrigan (Committee Member); Kelly Cohen Ph.D. (Committee Member); San-Mou Jeng Ph.D. (Committee Member); Mark Turner Sc.D. (Committee Member) Subjects: Aerospace Materials

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, 2011, Mechanical Engineering

A zero-dimensional fluid and thermodynamic model of an engine, cooling system, and exhaust system was developed in order to simulate the operation of an advanced thermal management system. The model was calibrated with experimental data where available. The thermal management system modeled in this work employed waste heat recovery to reduce engine, coolant, and lubricating fluid warm-up times and fuel consumption following a cold-start. The model was used to develop a control strategy for two valves in the exhaust system which control the flow of exhaust through an exhaust-to-coolant heat exchanger. The objective of the controller was to minimize coolant warm-up time without violating any of the system constraints. A model-based open-loop controller was developed that was able to reduce warm-up time by nearly 35% on the FTP city drive cycle while respecting the limitations of the system.

Committee: Marcello Canova Dr. (Advisor); Giorgio Rizzoni Dr. (Committee Member); Timothy Scott Dr. (Committee Member) Subjects: Automotive Engineering

Master of Science (MS), Ohio University, 2007, Mechanical Engineering (Engineering)

Methodology of and details on designing, constructing, and testing an efficient low power electric vehicle for alternative energy testing purposes. Experimental analysis of the drive motor operating temperature to determine feasibility of a thermal management system to preheat ammonia for improved efficiency of an electro-chemical reformer. Description of steps taken in preparation for the eventual inclusion of a hydrogen fuel cell and ammonia electrochemical reformer.

Committee: Gregory Kremer (Advisor) Subjects: Engineering, Mechanical