The effect of discharge areas on the operational performance of a liquid-ring vacuum pump: Numerical simulation and experimental verification

Abstract

To determine the effect of discharge area on the ability of a liquid-ring vacuum pump, the inspiratory capacity and shaft power are numerically investigated for different discharge areas adjusted by the number of discharge ports at different inlet pressures. Besides, the numerical results of these key operating parameters are verified by experiments in a developed testing system with a flexible valve plate on the discharge ports. The result shows that there exists an optimal discharge area of the liquid-ring vacuum pump at each inlet pressure, and good agreements are found between the experimental data and numerical results. For a 2BEC-40 vacuum pump, the maximum isothermal compression efficiencies can reach 39.99%, 46.80%, 49.16% and 40.82% for the inlet pressures of 20 kPa, 40 kPa, 55 kPa and 70 kPa with the optimum number of discharge ports is 1, 5, 12 and 12, respectively. The results suggest that the self-adaptive adjustment of discharge areas by the valve plates is of great importance to practical applications of a liquid-ring vacuum pump.