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45 SECTION 9 Problem Statements 9.1 Dependence of HAP Emissions (8 to 35 degrees Celsius [C], 4695 degrees Fahren- from Idling Aircraft heit [F]), and show that HAP emissions increase on Ambient Conditions greatly with decreasing temperatures. The lack of knowledge regarding the temperature dependence of AIRPORT COOPERATIVE RESEARCH HAP emissions, and how it depends on engine tech- PROGRAM PROBLEM STATEMENT nology, currently results in uncertainties of more than a factor of 2 in modeled HAP concentrations and risk. I. PROBLEM TITLE This is especially important for airports located in cold Dependence of HAP emissions from idling aircraft on environments. ambient conditions IV. RESEARCH PROPOSED II. RESEARCH PROBLEM STATEMENT This project would measure the emission rates of var- Frequently, commercial airport operators are asked to ious HAPs compounds from commercial aircraft as a estimate the magnitude of toxic emissions from air- function of thrust level near idle and as a function of port-related sources. These requests may come from environmental variables such as temperature, humid- government officials, courts, or concerned commu- ity and pressure. The project should quantify HAPs nity groups. One of the key categories of potentially emissions from a wide variety of in-service commer- toxic emissions is Hazardous Air Pollutant (HAP) cial aircraft under a wide variety of environmental emissions--and the most important source of airport conditions while operating in idle mode. It is envi- related HAPs compounds at most commercial air- sioned that this will require making measurements ports is idling jet engines. This is because the HAPs during summer and winter to achieve as wide a tem- emissions of modern jet engines are very small at perature range as possible. Measurements at more power settings greater than idle. It is therefore critical than one airport are desirable. It is essential that the to understand the rate of HAPs emissions at low engine type and thrust setting be determined during power settings. These emissions will vary as a function these measurements to separate their effects from of thrust setting, environmental variables (especially those of the environmental variables. temperature), and engine type. In order to properly estimate airport HAP emissions it is necessary to bet- V. ESTIMATE OF THE PROBLEM FUNDING ter understand the aircraft engine emission factors as AND RESEARCH PERIOD a function of these variables. Recommended Funding: $500,000 Research Period: 18 to 24 months III. OBJECTIVE The goal of this project would be to improve our VI. URGENCY AND PAYOFF POTENTIAL quantitative understanding of the largest aviation- This research will provide a detailed and quantitative related HAPs emission source--jet engines operating understanding of jet aircraft HAPs emissions as a at low power. Emissions data for commercial aircraft function of environmental and operational factors. are only available in the narrow temperature range The results will likely be incorporated in the U.S.