| The need for high-reliability, low cost, low vibration cryocoolers in both the military and commercial markets has spawned and continues to drive the development of pulse tube cryogenic refrigerators. Related to the Stirling cryocooler, the pulse tube cooler has the advantage over the Stirling of having no moving parts in the expander. The moving displacer of the Stirling is replaced in the pulse tube cooler with an orifice-surge tank assembly to achieve the desired phase shift between the mass flow rate and the pressure wave in the cryogenic region of the machine. This simpler expander design yields the potential for great improvements in the areas of reliability, cost, vibration, and resistance to contamination of the working fluid.;Though the fundamental science of pulse tube refrigeration is well understood, more accurate analytic and numerical modeling tools are needed to facilitate the development of higher efficiency pulse tube cryocoolers which can satisfy all of the requirements of the user community. At present one of the primary areas of uncertainty in pulse tube cryocooler modeling is in the calculation of the refrigeration losses occurring in the pulse tube itself. Calculation of these losses requires a thorough understanding and accurate modeling of the oscillatory velocity, pressure, and temperature distributions within the pulse tube gas.;Towards this end, a numerical model was developed to solve the one-dimensional, non-linear governing equations for the heat and mass flows in high-frequency pulse tubes. The model utilizes the method of lines. Dimensional analysis was performed to identify the important dimensionless groups and to facilitate the reduction of the governing system of equations to a dimensionless system. Parametric studies were conducted to analyze the influence of various operating conditions on the solution of the pulse tube equations. |
