This project is suggested by Nidec Global Appliance Germany GmbH. The company is interested in using CFD models to boost their development phase of hermetically sealed reciprocating compressors. In this thesis both a lumped model and a 2-D planar CFD/FSI model is set up in order to determine the dynamic response of a suction valve. The lumped model is based on non-steady valve flow equations. The lumped model is set up in MATLAB and is compared to data from computer simulation program KV-DYN due to lack of experimental data. The 2-D planar CFD/FSI model of a compressor is set up in ANSYS Fluent. The dynamic mesh method is used to account for the movement of the piston and the valve displacement. The CFD/FSI model is also compared to the data from KVDYN. The CFD/FSI model and the lumped is not directly compared given the lumped model is simplified to such an extended a comparison is difficult. The lumped is able to capture some features of a compressor cycle, among them, to a lesser extent the dynamic response of the suction valve. The CFD/FSI model is able to describe the non-steady flow phenomena in valve channels and the compressor cycle. It is expected the models can be used in the design phase of compressors if they are improved.