Types Of Pulse Tube Refrigerators Research Articles

Effect of Thermal Cycling on Operational Characteristics and Lifetime Prediction of Space Pulse Tube Refrigerator

This paper presents the operation status and results of ground thermal cycling test of pulse tube refrigerators (PTRs) for space application. Firstly, a thermal cycling degradation model was proposed by considering two physical mechanisms: contamination and fatigue damage. Then, a thermal cycling test scheme of two types of PTRs was designed and performed to demonstrate their long lifetime and high thermal stability. Two type A PTRs with cooling capacity of 1W@60 K and two type B PTRs with cooling capacity of 5W@80 K were continuously operated for about two years in a simulated vacuum thermal cycling environment. Effects of heat rejection temperature variation on thermal stability and dynamic performance of the PTRs were investigated. Furthermore, the thermal cycling degradation model was validated with the actual thermal cycling test data. Finally, the predicted pseudo-failure lifetime was acquired via experimental data and degradation model. Moreover, the estimated reliability of PTRs was obtained through using the Weibull distribution. The proposed thermal cycling test scheme and innovative lifetime prediction and reliability estimation method provide a quick and accurate approach for the cooler manufacturer to assess the lifetime and reliability of the space PTRs.

Performance analysis and optimization of high capacity pulse tube refrigerator

High capacity pulse tube refrigerator (HCPTR) is a new generation of cryocoolers tailored to provide more than 250 W of cooling power at cryogenic temperatures. The most important characteristics of HCPTR when compared to other types of pulse tube refrigerators are a powerful pressure wave generator, and an accurate design. In this paper the influence of geometrical and operating parameters on the performance of a double inlet pulse tube refrigerator (DIPTR) is studied. The model is validated with the existing experimental data. As a result of this optimization, a new configuration of HCPTR is proposed. This configuration provides 335 W at 80 K cold end temperature with a frequency of 50 Hz and COP of 0.05.

A new computational model for entire pulse tube refrigerators: Model description and numerical validation

In present paper, a new modeling approach for the performance of pulse tube refrigerator is proposed. The new approach combines one-dimensional and two-dimensional models (1-D and 2-DCC model) together, and can be used to simulate the fluid flow and heat transfer processes of the basic type, orifice type and double-inlet type pulse tube refrigerators (PTRs). With the present model, the complicated fluid flow and heat transfer characteristics in the PTR system can be efficiently depicted and the computational time can be greatly reduced. Then based on the approach, the distribution characteristics of the flow and temperature fields of the three types of PTR are numerically analyzed. The complicated fluid flow and heat transfer phenomena in PTR, such as DC flow, velocity and temperature annular effects are presented vividly. The numerical results show that the 1-D and 2-DCC model is reliable and practical, which can be used to explore the physical mechanism of the thermodynamic processes of the PTR system and optimize the design of the PTR system and its components.

First and second law analysis of pulse tube refrigerator

The first and second law of thermodynamics was used to analyze the orifice type and the double-inlet type of pulse tube refrigerator (PTR). Detailed dynamic characteristics of the thermodynamics, flow and heat transfer processes in the PTR were revealed, including the dynamic pressure variations, transient gas temperature, mass flow rate in the PTR. The exergy loss method was used to analyze each component in the PTR for the first time, and the performance coefficients of all components of PTR have been obtained. It was found that the performance coefficient of the double-inlet PTR was 0.108, 9% higher than that of the orifice PTR. The analysis also showed that the exergy efficiency of the double-inlet PTR was 29.95%, significantly higher than that of the orifice PTR (25.04%). In addition, it was found that the exergy losses in the regenerator and orifice were substantially larger than in other components of the PTR system. The optimal design of these two key components is, therefore, essential for the further improvement of the PTR performance.

Analytical treatment of counterflow pulse-tube refrigerators

In our laboratory we work an a new type of pulse-tube refrigerator. A complete set of relations is derived for the operation of counterflow pulse-tube refrigerators. The input parameters depend on the working fluid, the geometries of the pulse tube and the counterflow heat exchanger, and the compressor characteristics. The calculated molar flow in the heat exchanger agree within 5% with the measured value. The calculated and experimental lowest temperature and the temperature difference between the hot and cold gas in the heat exchanger agree within 10%. This larger difference is caused by difference between the modelled and real heat exchanger.

Phase shifting in pulse tube refrigerators

Different types of pulse tube refrigerators are described by alternative phasor diagrams based on the volume flow rates applied at the ambient temperature inlets of the regenerator and of the pulse tube(s). This provides a simple means for finding the optimum phase shift between pressure and flow rate for PTRs operated with different kinds of phase shifters such as the orifice system, the inertance tube, and the double inlet arrangement. The basic features are discussed first for ideal systems with no losses. Then, those results are compared with experimental data of single- and two-stage pulse tube refrigerators and also with more comprehensive numerical calculations which take account of irreversible losses caused by friction as well as heat conduction and heat transfer. It is shown that for the pulse tube, the phase shift can be well estimated from the ideal model, whereas there is more discrepancy for the regenerator. Those phasor diagrams are shown to be helpful tools for the design of multistage systems.

HTS microwave devices and subsystems with pulse tube refrigerators

Two new types of pulse tube refrigerators with optimized cooling power of 6 W at 77 K have been designed and fabricated. Experiments show that vibration of the pulse tube refrigerators is at least an order of magnitude smaller than that of Stirling coolers. Two microwave devices, a HTS cavity and a HTS miniature lumped band-stop filter, were integrated with the refrigerators and operated successfully, which demonstrated the potential application of these integrated devices and the refrigerator as practical HTS sub-systems.

Pulse tube refrigerator with low temperature switching valve: concept and experiments

The concept of a new type of pulse tube refrigerator, termed pulse tube refrigerator with low temperature switching valve, is proposed. It is suitable for industrial applications that require larger refrigeration powers. In this kind of pulse tube refrigerator a recuperative heat exchanger instead of a regenerator is used and a switching valve is installed at the cold end of an orifice pulse tube. The adiabatic expansion efficiency of the orifice pulse tube with low temperature switching valve, which actually works as a new type of expander, has been experimentally investigated. Adiabatic efficiencies higher than 40% have been achieved in the preliminary experiments. Methods for increasing the adiabatic efficiency are discussed.

パルス管冷凍機内の温度振動に及ぼす運転周波数の影響

This paper describes the influence of the driving frequency on the oscillating behavior of gas pressure and temperature inside a pulse tube refrigerator and the ultimate wall temperature at the cold end. Two types of pulse tube refrigerators, basic and orifice pulse tube refrigerators, are investigated. The length of the pulse tube is 300mm and its diameter is 13mm. The oscillation of the gas pressure and temperature at various points along the pulse tube refrigerator and the wall temperature distribution is obtained as a function of the driving frequency in the range from 1 to 18Hz. The gas pressure oscillation is quite similar at all measuring positions through the pulse tube for both types. However, the gas temperature oscillation differs from location to location along the pulse tube. The wall temperature at the cold end depends on the driving frequency and there exists an optimum range of the frequency within which the lowest value of the wall temperature is attained. It is found that typical frequencies in the optimum range are 3Hz for the basic type and 6Hz for the orifice type. The gas temperature oscillation at lower frequencies can be clearly distinguished from that at frequencies higher than the optimum values. Moreover, it is also shown that the differences in the oscillating behavior between both types are more noticeable at the lower driving frequencies.