True Bond Model of the Thermodynamics of a Compressed Gas Accumulator

摘要

An accumulator with a gas filled flexible bladder is a device often used in hydraulic systems. The paper presents a true bond graph model that accounts for the energy exchange between the hydraulic oil stored in the device and the trapped compressed gas. The model does not rely on one of the usual assumptions that the process is either adiabatic or isothermal and is verified by simulation. Results obtained for the poly-tropic case are compared with those in the adiabatic case. The new true bond graph model accounting for the entropy flow between the oil filled chamber and the gas filled rubber bag easily integrates into bond graph representations of usual hydrostatic models. Thus, it proves useful in practical engineering models of hydraulic systems.