Molecular and micromechanical energy analysis

From the chemical mechanisms governing hydrocarbon combustion to the micromechanics of efficiently delivering fuels, the Daily group investigates several aspects of energy and propulsion systems using methods both experimental (molecular beam spectrometry and laser spectroscopy) and theoretical (ab initio quantum mechanics, molecular dynamics). Specific projects include:

• Biomass thermochemical processing
• High pressure kinetics of syngas and nearly pure hydrogen fuels
• Actively controlled self-aspirating MEMS fuel injector

Fig: Modeling the expulsion stroke of a 1mm micropump.

Aerosol Particle Characterization and Health Effects

Aerosol particles span a range of sizes, from ultrafine nanoparticles (0.01 - 0.1 um) to coarse particles (2.5 - 10 um). Across this range, aerosols have a wide variety of sources and chemical makeup, from biological microbia to air blown dust particles; similarly, they can have a wide range of consequences on air quality and human health. Activities at CAQR investigate the content, origin and health impacts of aerosols using , laboratory experiments, field measurements, chemical transport models, time series analysis and source factorization. Current and ongoing projects are:

• Identification and classification of ultrafine particles (Miller, Hannigan)
• Health effects and characterization of urban and rural coarse particulate matter in northeastern Colorado (Miller, Hannigan, Milford)
• Denver Air pollution Sources and Health (DASH) study - a source-oriented approach to air pollution health effects (Miller, Hannigan)

Fig: Sources of sampled course particulate matter determined by factor analysis in Weld County (left) and Denver County (right).

Fig: Time series of nitrate aerosol concentrations outside (top), in the control lab (middle) and indoors (bottom).

Air pollution control and exposure

Linking ambient and indoor concentrations to actual personal exposure levels is a key step towards establishing causality of air quality on health. Application of existing and new control technologies to known air pollutant sources is often a balance between costs and benefits. The following activities at CAQR explore the extent of human exposure to air pollution under a wide range of conditions and address optimization challenges associated with implementing effective control strategies.

• Ultraviolet germicidal irradiation (Miller)
• Evaluation of crankcase filters and diesel oxidation catalysts for reducing children's exposure in school buses (Hannigan, Milford)
• Correlation of indoor airborne particulate matter with outdoor values (Miller, Hannigan)
• An assessment of indoor air quality in hispanic immigrant housing in Commerce City, Colorado (Miller)
• Carbon monoxide exposure in residences from unvented combustion appliances (Miller, Hannigan)
• Understanding air toxics and carbonyl pollutant sources at the urban/mountain interface (Milford, Hannigan)
• Cost effective emissions mitigation strategies for control of secondary inorganic aerosol in the U.S. (Henze)

Fig: Prof. Hannigan modeling the Personal Particle Speciation Sampler (PPSS).

Source Evaluations and Emissions Estimates

Air quality regulations require accurate knowledge of current pollutant concentrations and robust models for estimating how these concentrations will adjust in response to emissions regulations and global change. A key uncertainty in this process is specification of the emissions that give rise to pollutants such as aerosols, NO_x and O₃. The extent to which local concentrations are governed by emissions from abroad is important for establishing baseline targets. Specific projects related to source evaluations and model uncertainty are:

• Constraining trace gas emissions using satellite observations (Henze)
• Bayesian and adjoint model sensitivity analysis (Milford, Henze)
• Long-range pollution transport (Henze)

Energy Policies and Climate Impacts

Climate change and air quality are intrinsically linked owing to the commonality of the atmospheric constituents that drive both these aspects of the environment. Hence, energy strategies in response to climate change will inadvertently affect air quality and vice versa. The following efforts assess the impacts of current and future emissions from man made and natural sources on both air quality and climate:

• Air quality impacts of plug-in hybrid electric vehicles (Hannigan, Milford)
• Secondary organic aerosols from anthropogenic and biogenic hydrocarbon oxidation (Henze, Milford)
• Estimating the radiative forcing of emissions from specific source sectors and locations under present and future IPCC scenarios (Henze)