Experiments on Low-Temperature Diesel Combustion | Alternative Engine Fuels | Engine Combustion Modeling | Modeling of Biomass Thermochemical Conversion | Bio-oil Gasification | Biomass Gasification and Syngas Combustion
Experiments on Low-Temperature Diesel Combustion
This research is motivated by the federal emissions mandates, demands for fuel economy and durability, and the desire to explore the complex spray combustion phenomena in engines. We have developed a fully equipped, multi-engine test facility to characterize and optimize diesel engine combustion and emissions.
Low-temperature combustion is a strategy to reduce both NOx and particulate matter (or soot) emissions simultaneously. We strive to optimize engine operating conditions and combustion chamber geometry to achieve low emissions and high efficiency. The present approach is to utilize the advanced fuel injection system, ultra-high injection pressure, non-traditional injector nozzle designs, and exhaust gas recirculation to achieve low temperature combustion. The goal is to reduce exhaust emissions while maintaining high efficiency.
John Deere engine used for experiments (left); Graduate students working in the control room (center); Exhaust emissions analyzers(right).
High-pressure injection system
Effects of injector geometry on engine performance
Injection system characterization
Injection bench for injection rate characterization.
Diesel spray combustion diagnostics
Constant-volume chamber (left); Diesel spray image (center); High-speed, consecutive PLIF images of diesel spray at the same injection event.
Alternative Engine Fuels
In addition to conventional fuels, engine performance of using biorenewable fuels is also of our research interest. We perform engine tests and field studies to characterize engine emissions and fuel efficiency using various blends of biofuels including biodiesel, ethanol, renewable diesel, and pyrolysis oil derived from biomass. The goal is to develop fundamental understanding and strategies to adopt biofuels for engines.
Large diesel engine used for biodiesel combustion testing (left); Measuring exhaust emissions (right).
Energy recovery from waste plastics
Diesel engine used to characterize performance of biodiesel/polystyrene mixtures.
Ammonia engine – a non-carbon fuel
Ammonia engine (left); mixing system of ammonia and dimethyl ether (right).
Engine Combustion Modeling
Our work is among the first of its kind in incorporating detailed chemistry with 3-D computational fluid dynamics for homogeneous charge compression ignition engine simulation, and this approach has been widely adopted to characterize the fundamental low-temperature combustion processes. Overall, the research includes the development of various spray, fuel vaporization, heat transfer, combustion, and soot emissions models.
The four movies below show predicted in-cylinder spray, combustion temperature, flow structure and velocity, soot, and NOx distribution for a Caterpillar diesel engine.
Multicomponent Petroleum-Biofuel Vaporization
Next-generation engine simulation code
Modeling of Biomass Thermochemical Conversion
The code is being developed and validated to simulate the gas-particle flows inside a fast-pyrolysis reactor at Iowa State University laboratory. The code is available to the community upon request. The object-oriented programming strategy enables users to incorporate their own models effectively.
Fast pyrolysis of biomass to produce bio-oil has moved to the forefront of bioenergy research and development. Bio-oil, which is a mixture of complex oxygenated hydrocarbon species, is much easier to transport than bulky solid biomass. A novel approach is to convert biomass to bio-oil at widely distributed small-scale processing plants, transport bio-oil to a centralized location, gasify bio-oil to syngas, and upgrade the syngas to transportation fuels. This research is to investigate this approach through a combination of experimental and analytical studies that can potentially lead to the large-scale commercialization of this technology that has the potential to turn agricultural residues (e.g., corn cobs, corn stover, switchgrass, etc) into valued feedstock. This project is sponsored by Iowa Energy Center. Our group, as a team member of Bioeconomy Institute, will conduct experiments, technoeconomic analysis, reactor simulation, and plant optimization of biorefinery based on bio-oil gasification.
Biomass Gasification and Syngas Combustion
This research is focused on the utilization of biomass energy based on the gasification platform. Thermochemical gasification is a promising technology that is less restricted to the type of biomass. Gasification takes place at moderately high temperature and turns solid biomass into combustible gas mixtures (known as synthesis gas or syngas) through simultaneous occurrence of exothermic oxidation and endothermic pyrolysis under limited oxygen supply. Syngas derived from biomass gasification can be burned to generate heat and power or synthesized to produce liquid fuels.
The research is performed on a pilot-scale gasifier that incorporates a novel gas conditioning system for gas cleanup and an oxygen-enrichment system for gas upgrade. The gasifier consumes 5 tons per day of feedstock. Advanced instrumentation based on gas chromatograph and mass spectrometer (GC-MS) is used for characterizing the syngas composition as well as the exhaust flue gas emissions from the burner. This gasification/combustion system is being facilitated to develop clean burner for syngas combustion.
Gasification of biomass with controlled nitrogen contents
Biomass gasification using oxygen-enriched-air and steam
Low fuel NOx burner development
Burner mesh (left), predicted T and fuel NO(right).
Integration of geothermal energy into biorefinery