Design methods in active valve pulse tube refrigerator

The goal of this research is to develop a reliable and scalable design tool for active valve G-M type pulse tube refrigerators. The design tool builds upon a thermodynamic code, is based on given compressor power, and requires a deep understanding of key loss mechanisms. A test of the model has resulted in the fabrication of a single stage G-M type 5-valve pulse tube refrigerator designed to operate at 30K.; The design tool begins by focusing on the limitations imposed by the compressor and maximizes the ideal cooling power that can be produced from a compressor of fixed capacity. The process is illustrated using the specifications for a commercial compressor that draws a maximum electrical power of 5.5kW. The design defines the mass flow and compressor power as a function of the discharge and suction pressures, thereby producing a compressor performance map. The compressor performance map in turn provides a framework from which the pulse tube system geometry can be optimized for maximum cooling power. Various real constraints, such as acceptable pressure drop through the valves and regenerator, a laminar boundary layer along the pulse tube walls, and acceptable conduction losses are included in the design process and are shown to significantly impact the optimized result.; Accounting for the loss mechanisms in the design process is crucial in order to predict the performance of the system accurately and efficiently. A one dimensional, adiabatic numerical analysis has been performed to understand the DC flow and shuttle heat loss mechanisms which can be the main loss mechanisms in the G-M type pulse tube refrigerator. The analysis incorporates valve timing and considers the cold heat exchanger temperature. The combined effects of the DC flow and the shuttle heat loss on the temperature dependent cooling power are predicted by a numerical model of the 5-valve cycle. The analysis provides an improved prediction of the DC flow and the shuttle heat loss and an enhanced ability to scale the design of G-M type pulse tube refrigerators. The comparisons of the numerical model with a series of experimental results display good agreements.