Abstract
A supersonic gas ejector in conjunction with a liquid ring vacuum pump is used for creating and maintaining vacuum in a chamber for technological purposes. In this paper the authors submit an overview about the problematics of suction pressure reduction with a supersonic gas ejector used as a pre-stage of a liquid ring vacuum pump. This system has also the function of a cavitation protection due to the higher pressure present at the suction throat of the vacuum pump. A part of this paper is devoted to the governing equations used at the definition of the flow through an ejector. The experimental studies are then carried out in or own laboratory for verification purposes.
Highlights
The vacuum pumps are technological devices used to create and maintain vacuum for technological purposes
The required compression ratio (CR) of an ejector determines the ratio of the static pressures on the ejector exit to the pressure measured at the secondary suction throat of the ejector
The motion of the working fluid is given by the pressure difference between the atmospheric air at the primary inlet and the minimal suction pressure given by the vacuum pump
Summary
The vacuum pumps are technological devices used to create and maintain vacuum for technological purposes. The relatively low efficiency and the high minimal suction pressure can be considered as a disadvantage This minimal pressure is limited by the used working fluid inside the vacuum pump. The barrier of the minimal suction pressure, at which the vacuum pump can be used, is depending on the fluid properties, construction type, number of stages etc. This pressure is according to the following authors stated as: Bannwarth 5 kPa, Faragallah 15 kPa, Szabó 414 kPa. In the practice is a common requirement to reach a suction pressure, which is much lower than the listed values. This arrangement can reduce the pressure up to 1/5 of the initial pressure
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