AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Feasibility of Partial Air Recirculation for Vehicle HVAC System
HEEJUNG S. JUNG, Michael Grady, University of California Riverside
Abstract Number: 17 Working Group: Indoor Aerosols
Abstract On roadways, in-cabin exposures to ultrafine particles have been shown to be 10 times higher than ambient levels and contribute to approximately 50% of total daily ultrafine particle exposure among Los Angeles commuters. These results can apply to most of urban areas where high traffic volume exists. The high exposure at previous studies is because air on the roadway is entrained into the vehicle cabin. Scientists found cabin air-recirculation can reduce particle concentrations in the vehicle cabin significantly and effectively. However, their findings could not be applied to the cars in the market because of simultaneous increase of CO2 concentrations in the cabin. Partial recirculation of cabin air (as opposed to full recirculation and off/off control) suppresses the increase of cabin CO2 concentrations while taking advantages of air recirculation to reduce cabin particle concentrations. The study showed cabin CO2 concentration is determined by the balance between source strength and vehicle body leakage rate. This balance is influenced by multiple parameters: vehicle speed, cabin volume, fan speed, and number of passengers. The study demonstrated to control cabin CO2 concentrations at a certain target level by adjusting openings of the recirculation door angle. This method is a cost effective way of maintaining clean air quality of the cabin and can be applicable to new cars at a minimum cost. The presentation includes results and discussion from 1) feasibility test: proof-of-concept, 2) characterization of vehicle HVAC system, 3) influence of vehicle speed, 4) input parameters to control cabin CO2 concentration, and 5) mathematical modelling.