Reducing Mobile Air Conditioner (MAC) Power Consumption Using Active Cabin-Air-Recirculation in A Plug-In Hybrid Electric Vehicle (PHEV)

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.

Fuel Economy of Plug-In Hybrid Electric and Hybrid Electric Vehicles: Effects of Vehicle Weight, Hybridization Ratio and Ambient Temperature

“…conditioner (MAC) system. These reductions of 22% to 25% in fuel economy under UDDS falls between 13% (under on-road) and 35% (SC03 cycle without solar load) reduction reported by Li et al [11] for PHEV when their data are extrapolated for 95 °F (See their Figure 5). Fuel economy of HEV and PHEV reduced by 49%, 22 ± 7%, 39 ± 9% for the winter driving condition for blended CD mode with warm start, CS mode with warm start and CS mode with cold start, respectively.…”

“…The reduction in fuel economy in the summer driving condition is mainly due to the operation of mobile air conditioner (MAC) system. These reductions of 22% to 25% in fuel economy under UDDS falls between 13% (under on-road) and 35% (SC03 cycle without solar load) reduction reported by Li et al [11] for PHEV when their data are extrapolated for 95 • F (See their Figure 5). conditioner (MAC) system.…”

An Unobstructive Sensing Method for Indoor Air Quality Optimization and Metabolic Assessment within Vehicles

“…The aim was to assess energy expenditure during the growth periods of CO 2 buildup, and validate the model (by comparing using EE measurements taken from a reference instrument) at a condition where recirculating cabin air (RC mode) and outside air ventilation were alternated. Since regular, non-RC mode ventilation consumes more of the vehicles fuel in operation in comparison with RC mode [ 37 ], this condition is a practical solution to assure good quality levels in the air inside the car cabins while minimizing the fuel efficiency losses due to car cabin ventilation. In addition, these experimental conditions allow for the assessment of energy expenditure with the added benefit of being able to perform multiple EE measurements within a single trip, which improves the system’s accuracy with respect to assessment of the driver’s average energy expenditure.…”

Development of a Standard Testing Method for Vehicle Cabin Air Quality Index

“…More recently, Toyota has implemented active air recirculation condition to increase fuel economy in their 2017 Prius ECO mode driving [10]. Li et al [11]showed that cabin air recirculation improve not only cabin air quality but also fuel economy with a caveat that constant recirculation over a long period of time can lead to accumulation of CO 2 in the cabin.…”