油圧用プラダ形アキュムレータのエネルギー収支

第1報熱時定数の実験的検討

抄録

Gas-charged accumulators are being widely used as energy storage devices in hydraulic systems. During the gas compression and expansion process in the accumulator, the gas temperature varies and the heat is transferred between the charged gas and the accumulator wall. Thermodynamic losses occur during these processes. In this paper, a heat transfer model is considered for the energy balance of bladder-type accumulator. A thermal time constant, which is very important factor for this heat transfer model and influenced by a natural convection of charged gas, is experimentally investigated at constant gas volume after the rapid discharge of oil into the accumulator. A simple model for predicting thermal time constants based on the structure of bladder-type accumulators is proposed. The model can explain quantitatively the correlation between nondimensional gas volumes and nondimensional thermal time constants. Nondimensional gas pressure responses using the proposed model are calculated and compared with the experimental results.