Uma metodologia para otimização geométrica de serpentinas de compressores herméticos

Abstract

This paper aims to reduce the noise levels generated by reciprocating hermetic compressors. In these compressors, the noise is emitted mainly by sound radiation due to vibration of the housing. To minimize transmission of vibration energy through the discharge tube, a methodology of optimization the geometric shape of the discharge tube was used. Geometric modifications were made using the Genetic Algorithms optimization method. The discharge tube model was developed using commercial finite element software ANSYS®. Three forms of modeling were used: line (PIPE16), shell (SHELL63) and solid (SOLID45) elements. The results showed that the model which uses line elements is the most appropriate to represent the dynamics of the discharge tube. In order to generalize the geometrical modifications, the method calculates possible physics interference between the discharge tube and other parts of the compressors. To evaluate experimentally the effectiveness of the methodology a two-dimensional problem, analogous of the original threedimensional problem, was defined. The validation was successful, and the experimental results showed a reduction of 7.4 dB of mean square velocity of the optimized geometry with respect to the non-optimized geometry in the 500 1000 Hz frequency band. The spring, installed downstream of the muffle, were also evaluated. The spring acts as a vibrational energy dissipator of the discharge tube, thereby reducing the overall energy transmitted to the housing. The three-dimensional geometry of the discharge tube was optimized for three different frequency bands. Could be conclude that, as the width of the frequency band to be optimized increases, the reduction in energy transmitted decreases and the computational time increases.