Experimental Setup and Testing of a Variable Valve Actuation Enabled Cam-Less Natural Gas Engine

Doni Manuel Thomas, Purdue University

Abstract

A Cummins 6.7L natural gas engine enabled with VVA was installed in a research test cell at Purdue’s Ray Herrick Laboratories for experimental testing. The stock engine which was connected to an AC dynameter was mounted on a movable test bed outfitted with numerous sensors, a charge air cooler, and an external heat exchanger. In the engine control room, a few different systems were set up to run the dyno, collect data from the engine sensors, and monitor the safety apparatuses in the test cell. After the test cell setup was completed, an initial baseline testing was performed to compare the stock engine operation with the baseline engine data given in the Cummins fuel map. The testing was used to verify the engines stock functionality and troubleshoot some additional issues before setting the boundary conditions. Once the boundary conditions were set, a final stock engine testing was performed at rated to check for repeatability and verify stock engine operation following the engine modifications made to accommodate the VVA. Following the baseline testing, the VVA system was assembled on the standalone rig to verify its operation before mounting it on the engine. In order to run the natural gas valve profiles received from Cummins, the VVA controller gains were retuned and the LVDT sensors were calibrated so that the desired closing, opening and lift behaviors were achieved. After verifying the VVA’s functionality, the hardware was mounted on the engine for the VVA experimental testing. The initial VVA testing was focused on understanding the impacts of intake valve modulation on the gas exchange process. Based on previous simulation work, reductions in pumping work leading to better fuel economy is one expected outcome. Experimental testing data related to the engine performance and operation was used to compare each IVC case to the stock IVC timing. These results were also compared to the previous GT-Power work to identify any apparent trends. Future work includes using VVA to further improve efficiency in the part load region, and reduce knock at higher loads. Additionally, the incorporation of a laser based in-cylinder sensing system will help to optimize the capability of VVA.

Degree

M.Sc.

Advisors

Shaver, Purdue University.

Subject Area

Energy

COinS