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Cooling strategy for effective automotive power trains: 3D thermal modeling and multi-faceted approach for integrating thermoelectric modules into proton exchange membrane fuel cell stack

Description

Current hybrid vehicle and/or Fuel Cell Vehicle (FCV) use both FC and an electric system. The sequence of the electric power train with the FC system is intended to achieve both better fuel economies than the conventional vehicles and higher

Current hybrid vehicle and/or Fuel Cell Vehicle (FCV) use both FC and an electric system. The sequence of the electric power train with the FC system is intended to achieve both better fuel economies than the conventional vehicles and higher performance. Current hybrids use regenerative braking technology, which converts the vehicles kinetic energy into electric energy instead of wasting it. A hybrid vehicle is much more fuel efficient than conventional Internal Combustion (IC) engine and has less environmental impact The new hybrid vehicle technology with it's advanced with configurations (i.e. Mechanical intricacy, advanced driving modes etc) inflict an intrusion with the existing Thermal Management System (TMS) of the conventional vehicles. This leaves for the opportunity for now thermal management issues which needed to be addressed. Till date, there has not been complete literature on thermal management issued of FC vehicles. The primary focus of this dissertation is on providing better cooling strategy for the advanced power trains. One of the cooling strategies discussed here is the thermo-electric modules.

The 3D Thermal modeling of the FC stack utilizes a Finite Differencing heat approach method augmented with empirical boundary conditions is employed to develop 3D thermal model for the integration of thermoelectric modules with Proton Exchange Membrane fuel cell stack. Hardware-in-Loop was designed under pre-defined drive cycle to obtain fuel cell performance parameters along with anode and cathode gas flow-rates and surface temperatures. The FC model, combined experimental and finite differencing nodal net work simulation modeling approach which implemented heat generation across the stack to depict the chemical composition process. The structural and temporal temperature contours obtained from this model are in compliance with the actual recordings obtained from the infrared detector and thermocouples. The Thermography detectors were set-up through dual band thermography to neutralize the emissivity and to give several dynamic ranges to achieve accurate temperature measurements. The thermocouples network was installed to provide a reference signal.

The model is harmonized with thermo-electric modules with a modeling strategy, which enables optimize better temporal profile across the stack. This study presents the improvement of a 3D thermal model for proton exchange membrane fuel cell stack along with the interfaced thermo-electric module. The model provided a virtual environment using a model-based design approach to assist the design engineers to manipulate the design correction earlier in the process and eliminate the need for costly and time consuming prototypes.

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2014

A study of heating and degradation of acrylonitrile-butadiene-styrene/polycarbonate polymer due to ultraviolet lasers illumination during localized pre-deposition heating for fused filament fabrication 3D printing

Description

With the growing popularity of 3d printing in recreational, research, and commercial enterprises new techniques and processes are being developed to improve the quality of parts created. Even so, the anisotropic properties is still a major hindrance of parts manufactured

With the growing popularity of 3d printing in recreational, research, and commercial enterprises new techniques and processes are being developed to improve the quality of parts created. Even so, the anisotropic properties is still a major hindrance of parts manufactured in this method. The goal is to produce parts that mimic the strength characteristics of a comparable part of the same design and materials created using injection molding. In achieving this goal the production cost can be reduced by eliminating the initial investment needed for the creation of expensive tooling. This initial investment reduction will allow for a wider variant of products in smaller batch runs to be made available. This thesis implements the use of ultraviolet (UV) illumination for an in-process laser local pre-deposition heating (LLPH). By comparing samples with and without the LLPH process it is determined that applied energy that is absorbed by the polymer is converted to an increase in the interlayer temperature, and resulting in an observed increase in tensile strength over the baseline test samples. The increase in interlayer bonding thus can be considered the dominating factor over polymer degradation.

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2017

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Low cost system for test of thru-plane thermal transfer coefficient

Description

Determining the thermal conductivity of carbon gas diffusion layers used in hydrogen fuel cells is a very active topic of research. The primary driver behind this research is due to the need for development of proton exchange membrane fuels with

Determining the thermal conductivity of carbon gas diffusion layers used in hydrogen fuel cells is a very active topic of research. The primary driver behind this research is due to the need for development of proton exchange membrane fuels with longer usable life cycles before failure. As heat is a byproduct of the oxygen-hydrogen reaction an optimized pathway to remove the excess heat is needed to prevent thermal damage to the fuel cell as both mechanical and chemical degradation is accelerated under elevated temperatures. Commercial systems used for testing thermal conductivity are readily available, but are prohibitively expensive, ranging from just over $10,000 to $80,000 for high-end systems. As this cost can exclude some research labs from experimenting with thermal conductivity, a low cost alternative system is a desirable product. The development of a low cost system that maintained typical accuracy levels of commercials systems was carried out successfully at a significant cost reduction. The end product was capable of obtaining comparable accuracy to commercial systems at a cost reduction of more than 600% when compared to entry level commercial models. Combined with a system design that only required some basic fabrication equipment, this design will allow many research labs to expand their testing capabilities without straining departmental budgets. As expected with the development of low cost solutions, the reduction in cost came at the loss in other aspects of system performance, mainly run time. While the developed system requires a significate time investment to obtain useable results, the system can be improved by the used of RTDs in place of thermocouples or incorporation of an isothermal cold plate. These improvements would reduce the runtime to less than that of a standard work day while maintaining an approximate reduction in cost of 350%.

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Date Created
2016

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Investigation of chip production rate as an indicator of micromilling tool wear

Description

The demand for miniaturized components with feature sizes as small as tens of microns and tolerances as small as 0.1 microns is on the rise in the fields of aerospace, electronics, optics and biomedical engineering. Micromilling has proven to be

The demand for miniaturized components with feature sizes as small as tens of microns and tolerances as small as 0.1 microns is on the rise in the fields of aerospace, electronics, optics and biomedical engineering. Micromilling has proven to be a process capable of generating the required accuracy for these features and is an alternative to various non-mechanical micro-manufacturing processes which are limited in terms of cost and productivity, especially at the micro-meso scale. The micromilling process is on the surface, a miniaturized version of conventional milling, hence inheriting its benefits. However, the reduction in scale by a few magnitudes makes the process peculiar and unique; and the macro-scale theories have failed to successfully explain the micromilling process and its machining parameters. One such characteristic is the unpredictable nature of tool wear and breakage. There is a large cost benefit that can be realized by improving tool life. Workpiece rejection can also be reduced by successfully monitoring the condition of the tool to avoid issues. Many researchers have developed Tool Condition Monitoring and Tool Wear Modeling systems to address the issue of tool wear, and to obtain new knowledge. In this research, a tool wear modeling effort is undertaken with a new approach. A new tool wear signature is used for real-time data collection and modeling of tool wear. A theoretical correlation between the number of metal chips produced during machining and the condition of the tool is introduced. Experimentally, it is found that the number of chips produced drops with respect to the feedrate of the cutting process i.e. when the uncut chip thickness is below the theoretical minimum chip thickness.

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Date Created
2015