Select a CourseCourse DetailsReview MaterialsPrint Certificate

Presenter Bio: Mark Ereth

Mark H. Ereth, MD, Physician, Scientist, Inventor, TED speaker. Mark serves as Emeritus Professor, Mayo Clinic College of Medicine and Science, and Chief Medical Officer for SecureAire Technologies, LLC. Dr. Ereth is an internationally known expert in anesthesiology, and blood transfusion, and cardiopulmonary bypass and a frequent speaker at medical schools and hospitals around the world. Dr. Ereth’s career has been marked by innovation and collaboration. In his 25 years at the Mayo Clinic, he provided anesthesia and critical care to over 20,000 patients, directed a multi-disciplinary research group, and authored more than one hundred peer-reviewed journal articles and abstracts. He holds multiple patents for medical devices, and upon retirement from the Mayo Clinic, has focused on Indoor Air Quality. He presented his second TEDx talk entitled 'One Less...' at the U Tulsa TEDx conference focusing on the impact of combustion on pollution and disease. Mark also co-founded Cheetah Development, a non-profit based on a novel method of funding, Micro-Venture Capital.

Presentation Description:

Improved filtration efficiency in HVAC filters is typically associated with increased filter pressure drop and correspondingly, increased energy costs to maintain the same system flow rate.  Here, we show that appreciably enhanced filtration efficiencies without appreciably increased energy costs can be achieved through a combined filter unit wherein a pleated filter is mounted between sets of wire electrodes; with a high potential difference applied across electrodes upstream and downstream of the filter, incoming particles are ionized efficiently and consequently collected with a higher efficiency.  We specifically demonstrate this approach by testing MERV 11 and MERV 15 filters placed between wire electrode arrays with 0-10 kV applied in an ASHRAE 52.2. test duct, at face velocities between 0.64 – 1.91 meters per second.  Size-dependent filtration efficiency is quantified through a combination of an optical particle spectrometer (0.3 – 10 micrometers in diameter) as well as a scanning mobility particle spectrometer (10 nm – 0.3 micrometers in diameter).  With initial charge-neutralized challenge particles, we find without electric field implementation, both the MERV 11 and MERV 15 filters have collection efficiency minimums near 200-300 nm in diameter and for the MERV 11, the collection efficiency for the most penetrating size is below 50%.  However, with 10 kV applied across electrodes, the collection efficiency for the most penetrating size for the MERV 11 filter increases to be above 90% for all tested flow rates and similar performance for both the MERV 11 and MERV 15 filters for submicrometer particles.  To better understand the interplay between pressure drop and electrical energy required for operation, through these tests we also introduce a new figure of merit for HVAC control technologies, which is the product of the filtration efficiency and operating flow rate, divided by the sum of mechanical energy required for blower operation and the electrical power (voltage x current) for electrode operation.  With units of volume of air cleaned per unit of energy expended, the highest figures of merit are obtained for the MERV 11 test filter with 7 kV of applied voltage.  In total, our work demonstrates the synergistic effects of integrated filtration and active particle control.  Enhanced filter performance with active particle control could improve Indoor Air Quality with the resulting health and wellness benefits. 

University of Minnesota, Mayo Clinic College of Medicine and Science, SecureAire Technologies.