Numerical And Experimental Analysis Of A Stirling Type Single-stage Pulse Tube Cryocooler With Thermal Non-equilibrium Model

Stirling type single-stage pulse tube refrigerator with simple structure, high efficiency, high reliability, low vibration, has a wide range of applications such as military, superconductivity and medical care. Computational fluid dynamics tools (CFD) are applicable to describe the multi-dimensional flow and heat transfer characteristics, and have been used to investigate the working mechanism of pulse tube refrigerator for almost ten years. Most of researchers use the porous-media model to simulate the regenerator and the heat exchanger. However, the porous-media models available in CFD are equilibrium models, which are far from the practical conditions. Meanwhile, it is difficult to quantitatively investigate the real dynamical variations of parameters and the thermodynamic process of gas parcels for the complicate non-line effect in refrigerator. In addition, three conventional methods of inertance tube design are achieved based on the assumption of 1-D and laminar flow, which neglect the boundary treatment and turbulance effect, and can not describe the behavior of the gas in inertance tube. In view of these, research work is carried out which focuses on the following sections:1. The thermal equilibrium assumption in previous porous-media model is improved, and the thermal non-equilibrium model for simulations of cryogen reciprocating flow inside the cryocooler is developed. The empirical correlations and physical parameters, such as pressure loss, heat transfer coefficient and effective thermal conductivity, are analyzed for constructing more realistic model. The model is imported to the solver to attain the results, such as temperature, pressure and velocity field. Emphases are put on the real dynamical variations of parameters and the thermodynamic process of gas parcels, which is helpful to understand the working mechanism of pulse tube refrigerator.2. Analysis is carried out on the pulsatile turbulent flow in inertance tube and three conventional methods. The reason for poor agreement between computable dates and experimental dates is revealed. Finally, the pulsatile turbulent flow is numerically modeled using CFD method with different near wall treatments and turbulence models. The most suitable model is found out by comparing with experimental results.3. Experimental investigation on the pulse tube cryocooler driven by a linear compressor is carried out. The effect of operating parameters which include operating frequency, average pressure and input power on the performance of Stirling type single-stage pulse tube refrigerator is investigated and compared with the results by Sage. The good agreement is achieved.