Office: 1230 Mayo Phone: (612) 625-7135  praynor@umn.edu   B.S. Chemical Engineering, Cornell University M.S. Environmental Sciences and Engineering, University of North Carolina at Chapel Hill Ph.D. Environmental Sciences and Engineering, University of North Carolina at Chapel Hill

Research and Teaching Interests

Areas of interest include air filtration; air pollution control; measurement of volatile aerosols; metalworking fluids; aerosol physics; biological aerosols; exposure assessment.

Active Research

Supercomputer Modeling of Airborne Particle Filtration: Filter fiber manufacturers can produce fibers with highly irregular cross sections. The purpose of this research is to use a supercomputer to conduct a computational fluid dynamics study of the potential benefits these irregular fibers may offer for improved collection of airborne particles.

Evaporative Losses from Semi-Volatile Mist Samples: When they are sampled, metalworking fluid mists can evaporate, leading to an underestimation of the true workplace concentration. This project investigates the importance of evaporation of semi-volatile liquids sampled on filters using numerical modeling, laboratory experimentation, and field measurements.

Model Development for the Design of Better Mist Filters: The primary goal of this research is to develop improved numerical models for predicting the performance of wetted filters using data obtained from experiments. In particular, the models will be improved by adding information regarding filter dimensions and fiber materials.

Use of Vegetable Oils in Metalworking Fluid Formulations: The objective of this research is to begin a systematic development of emulsions of vegetable oils in water that can be utilized as metalworking fluids. Tests will measure if less mist is formed when these emulsions are used than when existing products are used.

Past Research

Long-Term Filter Performance in a Ventilation System: Some filters are made from fibers carrying electrostatic charges to enhance particle collection. This project compared the long-term efficiency and pressure drop performance of a set of filters with electrostatic enhancement to the long-term performance of standard filters to determine if the electrostatic enhancement was maintained.

Measuring Air Pollutants Near an Urban Ethanol Production Facility: The Gopher State Ethanol plant in St. Paul, MN created an odor problem for residents living near the facility. The purpose of this research was to identify and quantify odor-causing chemicals in the air in neighborhoods surrounding the plant.

Development of Bioaerosol Filtration Standard Test Methods: Bioaerosols are an increasingly important health concern. The goal of this research was to develop a test system for filter manufacturers to measure the efficiency of their filters at collecting airborne microorganisms.

A Virtual Impactor for Improved Mist Sampling Accuracy: Metalworking fluid mists and other volatile aerosols can evaporate when sampled onto filters. The goal of this project was to design and test a virtual impactor that could be used to measure volatile mist concentrations more accurately.

Selected Publications

Gina M. Letts, Peter C. Raynor, and Rebecca L. Schumann, "Selecting Fiber Materials to Improve Mist Filters", Journal of Aerosol Science, in press.

Peter C. Raynor and Soo Jae Chae, "The Long-Term Performance of Electrically Charged Filters in a Ventilation System", submitted to Applied Occupational and Environmental Hygiene

Peter C. Raynor and Soo Jae Chae, "Dust Loading on Electrostatically Charged Filters in a Standard Test and a Real HVAC System", Filtration and Separation, 40(2):35-39 (2003)

Peter C. Raynor, "Flow Field and Drag for Elliptical Filter Fibers", Aerosol Science and Technology, 36(12):1118-1127 (2002)

Peter C. Raynor, John Volckens, and David Leith, "Modeling Evaporative Loss of Oil Mist Collected by Sampling Filters", Applied Occupational and Environmental Hygiene, 15(1):90- 96 (2000)

Peter C. Raynor and David Leith, "The Influence of Accumulated Liquid on Fibrous Filter Performance", Journal of Aerosol Science, 31(1):19-34 (2000)

Jacky Rosati, David Leith, and Peter C. Raynor, "Determinants of Filter Lifetime", Filtration and Separation, 36(10):30-32 (1999)

Peter C. Raynor and David Leith, "Evaporation of Accumulated Multicomponent Liquids from Fibrous Filters", The Annals of Occupational Hygiene, 43(3):181-192 (1999)

Peter C. Raynor, Steven Cooper, and David Leith, "Evaporation of Polydisperse Multicomponent Oil Droplets", American Industrial Hygiene Association Journal, 57:1128- 1136 (1996)

David Leith, Peter C. Raynor, Maryanne G. Boundy, and Steven J. Cooper, "Performance of Industrial Equipment to Collect Coolant Mist", American Industrial Hygiene Association Journal, 57:1142-1148 (1996)

Steven J. Cooper, Peter C. Raynor, and David Leith, "Evaporation of Mineral Oil in a Mist Collector", Applied Occupational and Environmental Hygiene, 11(10):1204-1211 (1996)

G. Ramachandran, P.C. Raynor, and D. Leith, "Collection Efficiency and Pressure Drop for a Rotary-Flow Cyclone", Filtration and Separation, 31:631-636 (1994)