Chris Hogan from University of Minnesota, will give a presentation on his work about “Understanding and Exploiting Heat Transfer in Aerosols”.

About the seminar
A common assumption when analyzing an aerosol is that the particles and droplets are in thermal equilibrium with their surrounding gas. However, this is only true after a sufficiently long time scale; as particles grow via condensation and coagulation reactions, they heat up due to the conversion of latent heat to sensible heat. This talk will overview our group’s work in understanding the extent to which particles heat up in aerosol synthesis systems due to condensation and coagulation reactions, and the rate at which they cool down due to collisions with surrounding gas molecules.  We apply a combination of first principles theory and atomistic simulations to develop a framework to understand the timescales over which particles are not in thermal equilibrium with their surroundings after a coagulation or condensation event and how “hot” they can actually become. Following this, I will present our work in exploiting high heat transfer rates between particles and a liquid nitrogen “aerosol” (liquid nitrogen droplets in liquid nitrogen, at the nitrogen boiling point).  Droplets exposed to this aerosol can be cooled at rates exceeding 10⁴ K min⁻¹. We use this principle to develop aerosol-based cryopreservation systems for biological samples (cells). High cooling rates promote vitrification with minimal ice formation, allowing long-term preservation of cells without cryodamage.

About the presenter
Chris Hogan is the James J. Ryan Professor and Department Head in the Department of Mechanical Engineering at the University of Minnesota, Twin Cities, where has been a faculty member since 2009. His research group focuses largely on fundamental and applied research in aerosols, including the development of theories to describe transport and reactions in aerosols, the design of new measurement principles and instruments for aerosols, and the evaluation of HVAC control technologies. He has published more than 170 peer reviewed papers focusing in these areas, and is the editor-in-chief of the Journal of Aerosol Science.

Fika will be served from 11.00, and the seminar starts at 11.15.

Welcome to join!