Energy Merger Pipe Optimization of Hybrid Pneumatic Power System by Using CFD

Abstract

Outstanding characteristics of the hybrid pneumatic power system (HPPS) are the maintenance of the internal combustion engine (ICE) operation at its sweet spot of maximum efficiency, the recycling of the exhaust energy of the ICE, and the replacement of the battery's electric–chemical energy with flow work. Thus, the HPPS can be considered as a promising solution to increase energy efficiency and improve exhaust emissions. This paper presents study results concerning the flow energy merger capability of an innovative energy merger pipe which has been used in the HPPS. This energy merger pipe plays a major role in the merging process of both the high-temperature exhaust gas flow of an ICE and the high-pressure compressed airflow. This merging process can be significantly improved based on the analysis and evaluation of influences of the dimensions and contraction of the cross-sectional area (CSA) at the merging region of the energy merger pipe on the flow energy merger by using a computational fluid dynamic simulation. The results show that the flow energy merging process not only strongly depends on optimum dimensions of the energy merger pipe but is also significantly influenced by CSA adjustment for the change in the compressed airflow pressure. Under the optimum dimensions and the CSA adjustment for a better merging process, the exhaust gas energy recycling can reach about 80%; therefore, a vehicle equipped with HPPS can achieve efficiency that is approximately 40% higher than that of conventional vehicles.

Keywords:

• Hybrid pneumatic power system
• Energy merger pipe
• Energy efficiency
• Merger flow energy
• Exhaust gas recycling