Study on Pneumatics Responses of RC Circuits on Vacuum Condition

Abstract

A vacuum is frequently utilized for handling systems in factory automation. Because of the vacuum pressure, the change in state of air may differ from that of positive pressure systems during charge or discharge. However, pressure and temperature responses in the vacuum condition have not been examined up to now. Therefore, in this study the pressure and temperature responses of RC circuit in the vacuum condition is investigated. As a result, the research can be summarized as follows: 1) When the positive and vacuum pressure are compared in the same pressure ratio, it is found that the heat transfer rate is larger in the positive pressure case, because of the larger mixing effect.
2) The temperature responses are determined by the thermal-time constants. Since the vacuum pressure gets smaller thermal-time constants which concern the air density, the temperature responses show a smaller variation than those of positive pressure. Therefore, the pressure response is slower in the case of negative pressure.
The analysis method of pressure responses used in positive pressure conditions is feasible in the vacuum condition. This has been verified by experiment.