A new Stirling cryocooler model has been developed that is able to simulate the interactions between the loss mechanisms in the cold finger of the cooler. This one-dimensional, finite difference model can simulate single and two-stage cryocoolers. The model uses the latest friction factor and heat transfer correlations from the literature and simulates turbulence generation and thermal penetration depths. It runs fast enough to be useful for optimisation, thanks to a robust artificial convergence technique. The model includes a full representation of the cold finger, including the displacer motion and the flow past the displacer.

A two-stage Stirling cooler has been developed, and the model has been validated against measurements of its performance. The model predictions have also been compared to the predictions of a commercially available model and to the measured performance of single-stage Stirling coolers. The model is able to accurately predict a variety of measured values, including pressure swings and cooling powers. The model results show that there are significant interactions between the loss mechanisms of the simulated cryocoolers. The model was also used to investigate changes to the cold finger geometry of a single-stage cooler that would be difficult to simulate using other models; the model predicted that significant performance improvements could be made.