J. Ray Smith

HCCI Engine Control by Thermal Management

This work investigates a control system for HCCI engines, where thermal energy from exhaust gas recirculation (EGR) and compression work in the supercharger are either recycled or rejected as needed. HCCI engine operation is analyzed with a detailed chemical kinetics code, HCT (Hydrodynamics, Chemistry and Transport), that has been extensively modified for application to engines. HCT is linked to an optimizer that determines the operating conditions that result in maximum brake thermal efficiency, while meeting the restrictions of low NO{sub x} and peak cylinder pressure. The results show the values of the operating conditions that yield optimum efficiency as a function of torque and RPM. For zero torque (idle), the optimizer determines operating conditions that result in minimum fuel consumption. The optimizer is also used for determining the maximum torque that can be obtained within the operating restrictions of NO{sub x} and peak cylinder pressure. The results show that a thermally controlled HCCI engine can successfully operate over a wide range of conditions at high efficiency and low emissions.

Hydrogen as a future transportation fuel

A smooth transition from a petroleum-driven transportation system to clean-burning automobiles with the performance and range of todays gasoline cars is plausible using high-efficiency hydrogen-fueled hybrid-electric vehicles. The introduction of hydrogen (H2) vehicles will reduce U.S. dependence on oil imports, virtually eliminate automotive urban air pollution, accelerate the development of cost-effective renewable energy, and help stabilize greenhouse-gas emissions. Based on an economic and technical analysis, H2 vehicles, when first introduced, can be cost-competitive with battery-powered electric vehicles. As market penetration increases, H2-vehicle fueling costs would become competitive with the fueling costs of todays gasoline vehicles (5 ¢/mi). Hydrogen production at filling stations, vehicle fleets, and homes would circumvent many start-up issues and would use existing natural gas and/or electricity energy infrastructures to begin the transition towards a clean, flexible, sustainable, and secure transportation fuel.

Remote power systems with advanced storage technologies for Alaskan villages

This paper presents an analytical optimization of a remote power system for a hypothetical Alaskan village. The analysis considers the potential of generating renewable energy (e.g., wind and solar), along with the possibility of using energy storage to take full advantage of the intermittent renewable sources available to these villages. Storage in the form of either compressed hydrogen or zinc pellets can then provide electricity from hydrogen or zinc–air fuel cells whenever wind or sunlight are low. The renewable system is added on to the existing generation system, which is based on diesel engines. Results indicate that significant reductions in fossil fuel consumption in these remote communities are cost effective using renewable energy combined with advanced energy storage devices. A hybrid energy system for the hypothetical village can reduce consumption of diesel fuel by about 50% with annual cost savings of about 30% by adding wind turbines to the existing diesel generators. Adding energy storage devices can further reduce fuel use, and depending on the economic conditions potentially reduce life-cycle costs. With optimized energy storage, use of the diesel gensets can be reduced to almost zero, with the existing equipment only maintained for added reliability. However, about one quarter of the original fuel is still used for heating purposes.

Equivalence Ratio-EGR Control of HCCI Engine Operation and the Potential for Transition to Spark-Ignited Operation

This research investigates a control system for HCCI engines, where equivalence ratio, fraction of EGR and intake pressure are adjusted as needed to obtain satisfactory combustion. HCCI engine operation is analyzed with a detailed chemical kinetics code, HCT (Hydrodynamics, Chemistry and Transport), that has been extensively modified for application to engines. HCT is linked to an optimizer that determines the operating conditions that result in maximum brake thermal efficiency, while meeting the peak cylinder pressure restriction. The results show the values of the operating conditions that yield optimum efficiency as a function of torque and rpm. The engine has high NO{sub x} emissions for high power operation, so the possibility of switching to stoichiometric operation for high torque conditions is considered. Stoichiometric operation would allow the use of a three-way catalyst to reduce NO{sub x} emissions to acceptable levels. Finally, the paper discusses the possibility of transitioning from HCCI operation to SI operation to achieve high power output.

A Hybrid Vehicle Evaluation Code and Its Application to Vehicle Design

This paper describes a hybrid vehicle simulation model which can be applied to many of the vehicles currently being considered for low pollution and high fuel economy. The code operates in batch mode with all the vehicle information stored in data files. The code calculates fuel economy for three driving schedules, time for 0--96 km/h at maximum acceleration, hill climbing performance, power train dimensions, and pollution generation rates. This paper also documents the application of the code to a hybrid vehicle that utilizes a hydrogen internal combustion engine. The simulation model is used for parametric studies of the vehicle. The results show the fuel economy of the vehicle as a function of vehicle mass, aerodynamic drag, engine efficiency, accessory load, and flywheel efficiency. The code also calculates the minimum flywheel energy and power to obtain a desired performance. The hydrogen hybrid vehicle analyzed in the paper has a predicted range of 480 km (300 miles), with a gasoline equivalent fuel efficiency of 34.2 km/liter (80.9 mpg).

Thermal Charge Conditioning for Optimal HCCI Engine Operation

This work investigates a purely thermal control system for HCCI engines, where thermal energy from exhaust gas recirculation (EGR) and compression work in the supercharger are either recycled or rejected as needed. HCCI engine operation is analyzed with a detailed chemical kinetics code, HCT (Hydrodynamics, Chemistry and Transport), which has been extensively modified for application to engines. HCT is linked to an optimizer that determines the operating conditions that result in maximum brake thermal efficiency, while meeting the restrictions of low NO x and peak cylinder pressure. The results show the values of the operating conditions that yield optimum efficiency as a function of torque for a constant engine speed (1800 rpm). For zero torque (idle), the optimizer determines operating conditions that result in minimum fuel consumption. The optimizer is also used for determining the maximum torque that can be obtained within the operating restrictions of NO x and peak cylinder pressure. The results show that a thermally controlled HCCI engine can successfully operate over a wide range of conditions at high efficiency and low emissions.

Optimization of a CNG Series Hybrid Concept Vehicle

Compressed Natural Gas (CNG) has favorable characteristics as a vehicular fuel, in terms of fuel economy as well as emissions. Using CNG as a fuel in a series hybrid vehicle has the potential of resulting in very high fuel economy (between 26 and 30 km/liter, 60 to 70 mpg) and very low emissions (substantially lower than Federal Tier II or CARB ULEV). This paper uses a vehicle evaluation code and an optimizer to find a set of vehicle parameters that result in optimum vehicle fuel economy. The vehicle evaluation code used in this analysis estimates vehicle power performance, including engine efficiency and power, generator efficiency, energy storage device efficiency and state-of-charge, and motor and transmission efficiencies. Eight vehicle parameters are selected as free variables for the optimization. The optimum vehicle must also meet two perfect requirements: accelerate to 97 km/h in less than 10 s, and climb an infinitely long hill with a 6% slope at 97 km/h with a 272 kg (600 lb.) payload. The optimizer used in this work was originally developed in the magnetic fusion energy program, and has been used to optimize complex systems, such as magnetic and inertial fusion devices, neutron sources, and mil guns. The optimizer consists of two parts: an optimization package for minimizing non-linear functions of many variables subject to several non-linear equality and/or inequality constraints and a programmable shell that allows interactive configuration and execution of the optimizer. The results of the analysis indicate that the CNG series hybrid vehicle has a high efficiency and low emissions. These results emphasize the advantages of CNG as a near-term alternative fuel for vehicles.

Thermodynamic Analysis of Zero-Atmospheric Emissions Power Plant

This paper presents a thermodynamic analysis of a natural gas zero-atmospheric emissions power plant with a net electrical output of 400 MW. In this power plant, methane is combusted with oxygen in a gas generator to produce the working fluid for the turbines. The combustion produces a gas mixture composed of steam and carbon dioxide. These gases drive multiple turbines to produce electricity. The turbine discharge gases pass to a condenser where water is captured as liquid and gaseous carbon dioxide is pumped from the system. The carbon dioxide can be economically conditioned for enhanced recovery of oil, or coal-bed methane, or for sequestration in a subterranean formation. The analysis considers a complete power plant layout, including an air separation unit, compressors and intercoolers for oxygen and methane compression, a gas generator, three steam turbines, a reheater, a preheater, a condenser, and a carbon dioxide pumping system to pump the carbon dioxide to the pressure required for sequestration. The computer code is a powerful tool for estimating the efficiency of the plant, given different configurations and technologies. The efficiency of the power plant has been calculated over a wide range of conditions as a function of the two important power plant parameters of turbine inlet temperature and turbine isentropic efficiency. This simulation is based on a 400 MW electric power generating plant that uses turbines that are currently under development by a U.S. turbine manufacturer. The high-pressure turbine would operate at a temperature of 1089 K (1500 °F) with uncooled blades, the intermediate-pressure turbine would operate at 1478 K (2200 °F) with cooled blades and the low-pressure turbine would operate at 998 K (1336 °F). The corresponding turbine isentropic efficiencies for these three turbines were taken as 90, 91 and 93 percent. With these operating conditions, the zero-atmospheric emissions electric power plant has a net thermal efficiency of 46.5%. This net thermal efficiency is based on the lower heating value of methane, and includes the energy necessary for air separation and for carbon dioxide separation and sequestration.Copyright

A Coal-Fired Power Plant With Zero Atmospheric Emissions

This paper presents the thermodynamic analysis of a coal-based zero-atmospheric emissions electric power plant. The approach involves an oxygen-blown coal gasification unit. The resulting synthetic gas (syngas) is combusted with oxygen in a gas generator to produce the working fluid for the turbines. The combustion produces a gas mixture composed almost entirely of steam and carbon dioxide. These gases drive multiple turbines to produce electricity. The turbine discharge gases pass to a condenser where water is captured. A stream of carbon dioxide then results that can be used for enhanced oil recovery, or for sequestration. This analysis is based on a 400 MW electric power generating plant that uses turbines that are currently under development by a U.S. turbine manufacturer. The power plant has a net thermal efficiency of 42.6%. This efficiency is based on the lower heating value of the coal, and includes the energy necessary for coal gasification, air separation and for carbon dioxide separation and sequestration. The paper also presents an analysis of the cost of electricity (COE) and the cost of conditioning carbon dioxide for sequestration for the 400 MW power plant. Electricity cost is compared for three different gasification processes (Texaco, Shell, and Koppers-Totzek) and two types of coals (Illinois #6 and Wyodak). Cost of electricity ranges from 5.16 ¢/kWhr to 5.42 ¢/kWhr, indicating very little sensitivity to the gasification processes considered and the coal types used.Copyright