Prediction of Heat Transfer and Visualisation of Temperature Field in Screw Compressors

The heat transfer within a screw compressor is not considered to affect its performance significantly, because thermal energy dissipation represents less than 1% of the compressor power input. However, it can influence the machine reliability because heat transfer, resulting from the compression process, creates a non-uniform three dimensional temperature field leading to local distortions which may be larger than the clearances between the machine parts. This phenomenon is widely known and special control procedures are required to allow for start-up and shut down as well as for steady running operation without seizing. However, these are normally derived only from test data and may result in larger internal clearances than are really necessary, thereby reducing the optimum performance.
This paper describes a method for calculating the heat transferred during screw compressor processes, more precisely and hence how to obtain the temperature fields within the screw machine parts, which are needed to establish the size of the necessary clearances to maintain safe operating conditions.