Performance prediction of PTR for different pressure waveforms

Many researchers have shown that pulse tube refrigerator (PTR) performance depends significantly on the pressure waveforms generated by the rotary valve in a Gifford McMahon (GM) type PTR. Some literature has shown this effect experimentally for various waveforms. The design of the rotary valve therefore is very critical in order to generate an optimum pressure waveform. However, if the optimum waveform for obtaining maximum cooling power is known, it will help the valve design significantly. In view of this, the valve design would be improved significantly if the performance of the PTR could be predicted with reasonable accuracy for any pressure waveform. The present paper aims at developing a procedure to generate such predictions of the PTR performance for different pressure waveforms. This will help to determine an optimum pressure waveform for a given PTR configuration and will be useful in a significant way for the design of the rotary valve. An isothermal model of the PTR has been developed for various operational modes viz, Basic, Orifice pulse tube refrigerator (OPTR), double inlet pulse tube refrigerator (DIPTR), and has been validated with experimental results. The model is then extended to predict the PTR performance for various pressure waveforms. The experimental data, available in literature in the form of different pressure waves for a given PTR configuration, has then been analyzed. A comparison between the experimental results and the model predictions has been presented.