The efficiency increase reachable with more than one compression stage is a well known result of the thermodynamic principles, since this allows the gas cooling between consecutive stages and makes the transformation approach the isothermal limit.In the sliding vane rotary compressors is possible to integrate two stages of compression within a single stator, so to keep down the system dimension and its weight. However, for the specific compressor type at issue, some considerations on the optimization procedure to be followed in the design phase are required. The need of maintaining a fixed pressure level at the discharge port opening, the unavoidable reduction of the swept angle useful for the compression phase in each stage, the necessity of matching vane volumes in the stages with the cooling effect on the gas specific volume and some additional constraints imposed by system design (on the possible stator geometries) offer many theoretical aspect to be deepened, in order to obtain an optimized machine design in terms of thermodynamic efficiency.In the present paper the Authors developed a procedure which permits to define, starting from the choice of free parameters and the ideal performance expected, the optimum design in terms of ideal energy consumption. The procedure is based on a geometric and thermo-fiuid dynamic modeling of the phenomena which occur inside the compressor.
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