Summary

Reed type valves are commonly adopted in small reciprocating compressors due to their simplicity and low cost. In addition to the importance to the compressor volumetric and isentropic efficiencies, their suitable design is also crucial for reliability, since valves may be subjected to severe bending and impact stresses. The present work reports an optimization procedure for reed type valves considering efficiency and bending fatigue, which is attained by coupling a thermodynamic model for the compression cycle and a finite element model for the valve dynamics. Both models are coupled and a genetic algorithm is adopted to find different valve geometries that give the best compromise between efficiency and reliability. As an example, the method is applied to optimize the suction valve of a small reciprocating compressor. The optimal geometries found by the aforementioned procedure are prototyped and their performances verified through measurements in a compressor test bench. The dynamics and bending stress associated with one of the optimal geometries are predicted via a fluid-structure numerical simulation. Both the numerical and experimental results for the valve performance are found to be in good agreement with predictions obtained with the optimization procedure. The new procedure can be seen as an important tool in the initial phase of compressor design, when a first sketch of the valve geometry has to be found in a short period of time.

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