The Effect of Heavy-Duty Diesel Cylinder Deactivation on Exhaust Temperature, Fuel Consumption, and Turbocharger Performance below 3 bar BMEP 2020-01-1407
Diesel Cylinder Deactivation (CDA) has been shown in previous work to increase exhaust temperatures, improve fuel efficiency, and reduce engine-out NOx for engine loads up to 3 or 4 bar BMEP. The purpose of this study is to determine whether or not the turbocharger needs to be altered when implementing CDA on a diesel engine. This study investigates effect of CDA on exhaust temperature, fuel efficiency, and turbocharger performance in a 15L heavy-duty diesel engine under low-load (0-4 bar BMEP) steady-state operating conditions. Two calibration strategies were evaluated. First, a “stay-hot” thermal management strategy in which CDA was used to increase exhaust temperature and reduce fuel consumption. Next, a “get-hot” strategy where CDA and elevated idle speed was used to increase exhaust temperature and exhaust enthalpy for rapid aftertreatment warm-up. The “stay-hot” CDA strategy demonstrated increased exhaust temperatures up to 200°C while simultaneously reducing fuel consumption by 5-40% depending on the operating condition. The “get hot” CDA strategy demonstrated up to 200°C increases in exhaust temperature in addition to 10kW increase in exhaust enthalpy over baseline operation. The effect of CDA on the turbocharger performance was noticeable, but only affected a small part of the engine operating map where CDA was active. Overall, turbocharger efficiency decreased with CDA; however, the reduced pumping work from the deactivated cylinders still provided a fuel efficiency benefit. Examining the individual components, the compressor efficiency decreased with CDA due to the reduced engine air flow while the turbine efficiency increased. The study concluded that the same turbocharger as a non-CDA engine should still be selected for diesel CDA engines.
Andrew Morris, James McCarthy
Southwest Research Institute, Eaton Corporation