Study Of Internal Condensation Of Vapor In Small-Scale Pneumatic System

With the development of pneumatic system towards small scale and high speed, a new problem occurred in mature pneumatic technology, which is the condensation of vapor. The condensation of vapor in pneumatic system, especially internal condensation, affect system's performance and element's life greatly, so it is important to determine the occurrence of condensation and prevent system from it.In previous research, the mathematical model of the pneumatic system was established to get the numerical solution of the pneumatic flow field state during charging and discharging process. With the numerical solution, an internal condensation critical curve can be calculated out by condensation theory and depositing theory, on the curve, the enter water ability equal to the out water ability, which can be used as the basis to determine the occurrence of internal condensation. But the result doesn't coincide with the real completely. In this dissertation, we plan to get the critical curve by practical experiment results, because that the enter water ability only relates to the condensation density and the out water ability only relate to the volume ratio of the pneumatics system. Through the experiment, we can get the critical line denote by condensation density and volume ratio.Firstly, a dew-point control system was established, which can keep the dew-point of the supply air at a constant value range form -10℃~45℃.Secondly, when the supply pressure is constant, experiments were carried out with different supply air dew-point and volume ratio of the system. Then record the system whether occurring internal condensation or not as the experiment result. Then repeat the experiment under other supply pressure.Thirdly, the one-dimensional flow mathematics models of pneumatic charging and discharging system considering heat transfer and friction are established. Then pressure, temperature, velocity, and density of the flow field can be calculated out, according with the calculated results, we can calculate the condensation density of the pneumatic systems in the experiment.Finally, make volume ratio as the abscissa axe and condensation density as...