Experimental study of exhaust-gas energy recycling efficiency of hybrid pneumatic power system

Abstract

A hybrid pneumatic power system (HPPS) comprises an internal combustion engine (ICE), an air compressor, a high-pressure air storage tank, and a turbine, which stores the flow work instead of a battery's electrochemical energy; moreover, this system can recycle the exhaust-gas energy and make the ICE operate at its optimal point. Therefore, it can be viewed as a promising solution to increase a system's thermal efficiency and greatly improving exhaust emissions. This paper presents experimental study results concerning the operating capabilities of the HPPS and the effect of the contraction of the cross-sectional area (CSA) at the merging region of the energy merger pipe for the change in the compressed airflow pressure (Pair) on the exhaust-gas energy recycling of the HPPS. The experiments were performed on an HPPS that uses an innovative energy merger pipe with a total length of 530 mm, a diameter of 34 mm, and an angle between the two pipes of 30°, and the CSA was adjusted for the change in Pair. The experimental results show that the exhaust-gas energy recycling and the merger flow energy are significantly dependent on the CSA adjustment for the change in Pair. The optimum conditions for the best merging process can be achieved at a CSA of around 5–35% in the full range of Pair. Under these conditions, the exhaust-gas energy recycling efficiency reached approximately 75–81%; therefore, a vehicle equipped with an HPPS can achieve efficiency that is approximately 40% higher than that of conventional vehicles. Copyright © 2009 John Wiley & Sons, Ltd.