An Experimental Thermal Time-Constant Correlation for Hydraulic Accumulators

Abstract

A thermal time-constant correlation based on experimental data is presented for gas-charged hydraulic accumulators. This correlation, along with the thermal timeconstant model, permits accurate prediction of accumulator thermodynamic losses and the gas pressure and temperature history during compression or expansion. The gas is treated as a real gas, and all properties are allowed to vary with both pressure and temperature. The correlation was developed from heat transfer data obtained with a 2.5 liter piston-type accumulator charged with nitrogen gas. Both horizontal and vertical orientations were studied. The experiments covered the range, 2.6×108<Ra*<9.5×1010, 0.77<L/D<1.50, and 0.71<T*<1.0. The gas pressure was varied between 1.0 and 19.5 MPa.