Theoretical simulation of steady flowing manifold in hybrid pneumatic power system

Abstract

Improving the energy efficiency of existing power systems is part of energy conservation and carbon reduction efforts. Internal combustion engines (ICEs) are currently the most commonly used power source in transportation, and they can be combined with gas power sources to form hybrid power systems for enhanced energy efficiency and potential commercialization. This study introduces hybrid pneumatic systems that integrate energy from ICEs and exhaust gas through a manifold to reuse waste heat. However, the turbulence caused by compressed air in the manifold can prevent the smooth transfer and mixing of thermal energy, leading to reduced power at the final outlet. We use ANSYS Fluent software to conduct heat flow streamline analysis of the three-dimensional flow field in the manifold structure, with key parameters including throttle valve opening, manifold geometry, pressure, and temperature. Through this analysis, we explore the flow situation and heat transfer phenomenon inside the pipe, observe the flow field changes in the pipe, and adjust the diameter of the compressed air end channel for effective thermal energy. A backflow with velocity magnitude up to 72 m/s in high pressure case can be solved by compressing pipe and temperature increases from 349.9 K to 682.5 K with more efficient heat transfer and gas mixing. Thermal power, enthalpy, and mass flow rate of the hybrid power system are also investigated, enabling the ICE to operate at its optimal point. The waste heat from the ICE can also be recycled and converted into effective mechanical energy through flow work.