Heat transfer is one of the largest causes of exergy destruction in modern engines. In this paper, exergy distribution modeling was used to determine the potential of reduced engine heat transfer to provide significant gains in engine efficiency. As known from prior work, of itself, reducing heat transfer creates only a small increase in efficiency-most of the exergy is redirected into the exhaust stream-requiring both mechanical and thermal recovery of the exhaust exergy. Mechanical regeneration, through turbocharging and over-expansion, can lead to efficiencies exceeding 50%. Adding thermal regeneration, through high enthalpy steam injection or a bottoming cycle, can increase the efficiency potential to approximately 60%. With implementation of both mechanical and thermal regeneration, the only remaining cause of substantial exergy destruction is the combustion process. Thus, efficiency gains significantly beyond 60% are only possible by reducing the entropy generated in the fuel conversion process.
The use of neat alcohols, namely methanol and ethanol, in direct-injection, compression-ignited engines is difficult, most notably due to their poor ignitability. By employing a high-temperature combustion strategy, this challenge may be overcome, thus creating the opportunity for using these oxygenated and inherently low-sooting fuels for heavy-load applications.Experimental data are provided from a single-cylinder research engine that shows particulate matter (PM) emissions for Diesel-style combustion of both methanol and ethanol that are below the current US Government regulation limit. The level of particulates remained low up to stoichiometric ratios of fuel and air. A complete emissions analysis indicates a high combustion efficiency of ∼ 96% at stoichiometric conditions.In order to achieve reliable combustion, some form of intake-air preheating was required. The issue of ignitability is addressed with modeling which indicates that highly turbocharged, non-intercooled air into a cylinder with low heat rejection (LHR) surfaces can achieve conditions that satisfy acceptable ignition delay requirements. With increased exhaust enthalpy, opportunities exist to use thermal or mechanical exhaust regeneration strategies. All of these features contribute to a clean, high-efficiency Diesel engine with heavy-load capability.To explore the nature of soot formation within alcohol spray jets, images are provided from another single-cylinder device with optical access. The images show single-plume combustion for both methanol and ethanol into an air environment similar to that of an engine. Broadband luminosity is observable for both fuels within the interior of each jet. This indicates that a balance exists between soot formation and oxidation, the difference of which is responsible for engine-out emissions.
This Tech Assist/Fire Safety Assessment provides a comprehensive assessment of the lOOK Area Facilities at the U. S. Department of Energy's Hanford Site for fire protection upgrades that may be needed given the limited remaining service life of these facilities. This assessment considers the relative nature of observed fire risks and whether the installed fire protection systems adequately control this risk. The analysis is based on compliance with DOE Orders, NFPA Codes and Standards, and recognized industry practice. Limited remaining service life (i.e., 6 to 12 years), current value of each facility, comparison to the best protected class of industrial risk, and the potential for exemptions from DOE requirements are key factors for recommendations presented in this report.
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