Abstract
Air conditioner power consumption accounts for a large fraction of the total power used by hybrid and electric vehicles. This study examined the effects of three different cabin air ventilation settings on mobile air conditioner (MAC) power consumption, such as fresh mode with air conditioner on (ACF), fresh mode with air conditioner off (ACO), and air recirculation mode with air conditioner on (ACR). Tests were carried out for both indoor chassis dynamometer and on-road tests using a 2012 Toyota Prius plug-in hybrid electric vehicle. Real-time power consumption and fuel economy were calculated from On-Board Diagnostic-II (OBD-II) data and compared with results from the carbon balance method. MAC consumed 28.4% of the total vehicle power in ACR mode when tested with the Supplemental Federal Test Procedure (SFTP) SC03 driving cycle on the dynamometer, which was 6.1% less than in ACF mode. On the other hand, ACR and ACF mode did not show significant differences for the less aggressive on-road tests. This is likely due to the significantly lower driving loads experienced in the local driving route compared to the SC03 driving cycle. On-road and SC03 test results suggested that more aggressive driving tends to magnify the effects of the vehicle HVAC (heating, ventilation, and air conditioning) system settings. ACR conditions improved relative fuel economy (or vehicle energy efficiency) to that of ACO conditions by ~20% and ~8% compared to ACF conditions for SC03 and on-road tests, respectively. Furthermore, vehicle cabin air quality was measured and analyzed for the on-road tests. ACR conditions significantly reduced in-cabin particle concentrations, in terms of aerosol diffusion charger signal, by 92% compared to outside ambient conditions. These results indicate that cabin air recirculation is a promising method to improve vehicle fuel economy and improve cabin air quality.
Highlights
New government regulations have demanded an increase in automotive fuel economy (MPG—miles per gallon) to reduce dependency on imported oil for transportation [1,2]
air conditioner on (ACR) conditions significantly reduced in-cabin particle concentrations by 85% and 92% in comparison to ACF conditions and ambient conditions, respectively. These results suggest that the driver who compared to air conditioner off (ACO) conditions by ~20% and by ~8% compared to ACF conditions for SC03 test and on-road test, respectively
These results suggest that the driver who operates the vehicle with ACR conditions can increase vehicle fuel economy and improve cabin air quality with the caveat that ACR can lead to accumulation of CO2 in the cabin
Summary
New government regulations have demanded an increase in automotive fuel economy (MPG—miles per gallon) to reduce dependency on imported oil for transportation [1,2]. This pushed automotive manufacturers to improve the efficiency of the powertrain design, but they had to consider improving other components and systems in the vehicle. The mobile air conditioner (MAC) is the largest consumer of accessory vehicle power. Reducing MAC power consumption is important for all types of cars, namely ICE (internal combustion engine) vehicles, HEVs (hybrid electric vehicles), PHEVs (plug-in hybrid electric vehicles), and BEVs (battery electric vehicles) to improve vehicle fuel economy and driving range per full fuel tank or charge
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