Christopher L. Hagen

Electric Field Measurements in Gases Using Cavity Enhanced Polarimetry

We report a novel form of cavity enhanced polarimetry to make electrical field measurements in gases via the optical Kerr effect. The measurement system uses a distributed feedback laser at 1742 nm as the light source and an optical cavity with finesse of 170,000. Electrical field measurements are made in gases between two parallel plates. The high finesse of the optical cavity provides higher sensitivity as compared to past measurements using single- or multi-pass cells. Measurements are presented for carbon dioxide, nitrogen, oxygen, and air. Experimental results are compared against model predictions based on published Kerr constants. Effects of laser linewidth (phase noise) and the experimental detection limit are discussed.

Development and Analysis of Micro-Channel Heat Exchangers for Natural Gas Cooling

Abundant availability and potential for lower CO2 emissions are drivers for increased utilization of natural gas in automotive engines for transportation applications. However scarce refueling resources for on-road vehicles impose an infrastructure limited barrier on natural gas use in transportation. A novel ‘bimodal’ engine which can operate in a compressor mode has been developed that allows on-board refueling of natural gas where available without the need for any supplemental device. Engine compression of natural gas however results in considerable heating of the gas which is undesirable from a system stand-point. Micro-channel heat exchangers have been developed to absorb heat from the natural gas using engine coolant and compressed air. This work presents the design and development of the micro-channel heat exchangers as well as a preliminary analysis of system performance. Design methodology for the heat exchanger was based on trade-off studies that correlated system performance with component design. Energy flows through the system are analyzed as a function of engine compression ratio, operating speed, charge flow rate, and ambient air and natural gas conditions. These results are further used to estimate heat transfer co-efficient and effectiveness of the micro-channel heat exchanger. Future work involves developing CFD models of the heat exchanger to obtain a detailed understanding of the conjugate heat transfer and fluid flow processes within the micro-channels.Copyright

Self-Regulating System for Natural Gas Cooling in a Bimodal Internal Combustion Engine

Natural gas is an attractive option for transportation applications in the United States due to its abundant availability and potential for reduced emissions. The scarcity of refueling resources imposes a barrier to widespread use of natural gas in internal combustion engines. The development of a novel bi-modal engine capable of operating in a compressor mode provides refueling capabilities without any supplemental devices and attempts to overcome this infrastructure limited barrier. Heat generated in the compression process however results in undesirable effects such as increased work input for compression, pre-heating of natural gas stored in the fuel tank, and thermal loads in the components used in the modified cylinder head. In order to make the system self-contained, heat exchangers that utilize engine coolant as a heat sink are included in the system design to maintain natural gas temperatures at an acceptable level in between compression stages. This is planned to be done in a novel fashion so as to make the system self-regulating permitting the cooling of natural gas while maintaining the coolant temperature in the cylinder head at acceptable levels to maintain combustion efficiency. To this end, an EES model of the system that incorporates elements of the original vehicle coolant system and modifications made to incorporate the heat exchangers is developed and analyzed to ensure satisfactory performance. Parametric studies of system performance as a function of varying heat loads are used to determine the best strategy to maintain acceptable natural gas temperatures without causing a drop in engine performance.Copyright

Simulation of Turbocharged Marine Diesel Engine for Electrical Power System Trainer

This paper presents an application of the mean value combustion model to simulate large bore turbocharged diesel engines, coupled with large electric AC synchronous generators, to mimic power generation within a training simulator for a ship board electrical power system. A mean value engine model has been developed to simulate the most prevalent phenomena occurring in diesel direct injection internal combustion engines. The combustion process is modeled as a mean value system where characteristics of combustion are averaged over the entire cycle. Detailed models of the air intake, fuel delivery, and internal/external cooling systems have been developed using concepts from fluid dynamics and thermodynamics. The engine model has been created in MATLAB® Simulink® to simulate actual hardware signals sent to the power management controller to facilitate the development of the power system trainer. The model has been structured so that it is highly adaptable and is capable of simulating a wide variety of engine bore sizes and cylinder numbers which has significantly increased the utility of the work presented herein.Copyright