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Automotive manufacturers relentlessly explore engine technology combinations to achieve reduced fuel consumption under continued regulatory, societal and economic pressures. For example, technologies enabling advanced combustion modes, increased expansion to effective compression ratio, and reduced parasitics continue to be developed and integrated within conventional and hybrid propulsion strategies across the industry. A high-efficiency gasoline engine capable for use in conventional or hybrid electric vehicle platforms is highly desirable. This paper is the first to two papers describing the development of a combustion system combining lean-stratified combustion with Miller cycle for downsized boosted applications. The work was completed under a multi-year US DOE project. The goal was to define a light-duty engine package capable of achieving a 35% fuel economy improvement at US Tier 3 emission standards over a naturally aspirated stoichiometric baseline vehicle. A multi-mode combustion system was developed enabling highly efficient lean-stratified operation at light-load and stoichiometric Miller-cycle operation at mid- to high-loads. Some of the unique challenges in synergistically combining the two concepts are highlighted in this paper. A central direct-injection four-valve layout was designed with high-tumble ports and a bowl-in-piston capable of stable operation under highly dilute (lean plus EGR) mixtures when properly matched to fuel spray characteristics, a multiple-injection strategy, and a high-energy ignition system. Other challenges specific to meeting exhaust emissions requirements with a high-efficiency engine are also explored in this study. In this Part 1 of the paper, the single-cylinder combustion system design, analysis, and testing is described. Multi-cylinder engine system design, analysis and development is described in Part 2 of the paper [1].

Automotive manufacturers relentlessly explore engine technology combinations to achieve reduced fuel consumption under continued regulatory, societal and economic pressures. For example, technologies enabling advanced combustion modes, increased expansion to effective compression ratio and reduced parasitics continue to be developed and integrated within conventional and hybrid propulsion strategies across the industry. A high-efficiency gasoline engine capable for use in conventional or hybrid electric vehicle platforms is highly desirable. This paper is the second of two papers describing the multi-cylinder integration of a technology package combining lean-stratified combustion with Miller cycle for downsized boosted applications. The first paper describes the design, analysis and single-cylinder testing conducted to down-select the combustion system deployed to the multi-cylinder engine. This paper defines a light-duty engine package capable of achieving a 35% fuel economy improvement at US Tier 3 emission standards over a naturally aspirated stoichiometric baseline vehicle. A multi-mode combustion system was developed enabling highly efficient lean-stratified operation at light-load and stoichiometric Miller-cycle operation at mid- to high-loads. A central direct-injection four-valve layout was designed with high-tumble ports and a bowl-in-piston capable of stable operation under highly dilute mixtures when properly matched to fuel spray characteristics, injection strategy, and a high-energy ignition system. Boost system layout and base engine architecture were selected to minimize parasitics and maximize aftertreatment effectiveness. A multi-cylinder engine was developed and calibrated over a steady-state map. Results fed vehicle simulations over the EPA city and highway test cycles to predict the fuel economy improvement and tailpipe emissions potential. Fuel economy improvements over the baseline vehicle were projected at 42% and 39% for active-urea and passive-ammonia SCR aftertreatment systems respectively. Controls complexity to achieve regulatory compliance and the cost of the lean aftertreatment system were identified as the primary challenges to commercial viability.

The majority of first-generation Spark Ignition Direct Injection (SIDI) engines use Side-Injection, High Pressure Direct Injection (HPDI) combustion systems. Central-Injection is emerging as an alternative secondgeneration system. Side-Injection systems have an advantage in injector and spark plug packaging and cooling. Emission control systems are available for meeting current Japanese and European regulations. Central-Injection systems require the injector and spark plug to be closely spaced in the hotter and more crowded valve bridge area. This can pose potential development challenges with injector deposits and spark plug fouling. A potential benefit of Central-Injection is improved containment of the charge within the piston bowl, without wall guiding, resulting in lower emissions for future applications. This paper presents results from three different engines used to assess Central-Injection as a second-generation SIDI technology. Specifically, a Spray Jet, Air Pressureassisted DI (APDI) combustion system was used to compare with PFI and Side-Injection HPDI systems. The emission advantages of Central-Injection APDI, along with the fuel consumption, packaging and application issues, are discussed.

The \"PCO\" nozzle is a new design for direct injection diesels. It uses an outward opening poppet valve with orifices similar to those in hole-type nozzles. Hydrocarbons, NOx, light duty particulates and noise can be reduced. The orifices are completely covered when the valve is closed. No \"sac\" or orifice fuel can escape into the cylinder to increase hydrocarbons. The initial injection rate is reduced, lowering emissions and noise. With a near-vertical installation, the PCO can be substituted for hole-type nozzles and use the same combustion system. No fuel leakoff is required. Tests have been conducted in dynamometer engines and vehicles. Performance can be a trade-off, depending on the combustion system match. Remaining development work includes re-optimizing the combustion system for the PCO, enhancing the rate control capability, and demonstrating durability. Nozzle coking has been minimized with design and installation improvements but remains a concern.

Implementation of engine turnoff at idle is desirable to gain improvements in vehicle fuel economy. There are a number of alternatives for implementation of the restarting function, including the existing cranking motor, a 12V or 36V belt-starter, a crankshaft integrated-startergenerator (ISG), and other, more complex hybrid powertrain architectures. Of these options, the 12V beltalternator-starter (BAS) offers strong potential for fast, quiet starting at a lower system cost and complexity than higher-power 36V alternatives. Two challenges are 1) the need to accelerate a large engine to idle speed quickly, and 2) dynamic torque control during the start for smoothness. In the absence of a higher power electrical machine to accomplish these tasks, combustion-assisted starting has been studied as a potential method of aiding a 12V accessory drive belt-alternator-starter in the starting process on larger engines. The combustion-assisted cranking system has been implemented on a 5.3L V-8 engine with automatic transmission in a full-size truck. Integration of the BAS system controls with powertrain fuel and spark management shows the importance of combustionassist within the first several compression events. The use of a cylinder-event-based spark strategy was found to benefit the feel of auto-starts, as measured by passenger seat track vibrations. Introducing fuel into the cylinders during the shutdown showed up to 40% improvement in engine start times. Furthermore, this paper reports the feasibility of auto-starts from shutdown fuel in terms of start consistency and shows the need for a quick synchronization process of the powertrain control module if a 12-volt system is to be successfully used.

Cycle-to-cycle cylinder pressure variation has been observed in a CFR prechamber diesel engine when low ignition quality (low cetane number) fuels are burned. A statistical analysis of this phenomenon for various fuels and blends with cetane numbers as low as zero has been made. Operating conditions used were those specified by the ASTM Cetane Method for rating diesel fuels, in which the inlet air temperature is 150°F. Additional analysis was made at increased inlet air temperatures of 250°F and 350°F. The cycle-to-cycle variation has been characterized by the variation in the ignition (or pressure rise) delay time. It has been found to increase sharply as fuel cetane number is decreased below 20. The variation in dynamic injection timing was also measured and correlated with that for ignition delay. It has been concluded that the observed injection timing irregularities have no significant effect on ignition delay time, and that the autoignition process becomes unstable due to other factors when fuels of low ignition quality are burned.

Lowering the temperature of heating hot water systems is a key step toward decreasing energy used to heat buildings, and toward decarbonization and electrification As buildings move toward decarbonization and electrification, it is increasingly important for engineers to incorporate lower heating water temperatures into the design of building hydronic heating systems to most efficiently apply both natural gas boilers and electric refrigeration machines as heating sources. [...]lowering the mean water temperature in the example finned tube radiator from 170°F to 110°F lowers the heating output by approximately 65% Should the heating demand during extreme winter conditions exceed hydronic heating device capacity with 120°F heating hot water supply temperature, the supply water temperature from the condensing boilers and/or heat recovery chiller can be programmed to increase to accommodate the increased demand, with very modest impact on overall annual efficiency. Lowering the water temperature in hydronic heating systems can increase boiler efficiency to a significant extent when condensing natural gas boilers are installed, thus reducing a building's carbon footprint. Condensing gas boilers, heat recovery chiller aid retrofit A MUSEUM HVAC RETROFIT in a cold climate benefitted from new hydronic heating devices In this existing museum in Southeast Michigan, the original heating, ventilation and air conditioning (HVAC) system design incorporated a comparatively inefficient district steam system as the primary heating source for the building's hydronic heating system, making 180°F heating hot water via a shell and tube heat exchanger.