Sharif Digital Repository

In spite of numerous attempts which have been made during the last decade to optimize pulse tube refrigerators, still theoretical and analytical realization of this device needs to be thoroughly explained. In this paper, in addition to the oscillatory flow analysis in the pulse tube refrigerator through a simple analytical model, the performance of the alternate tube section of this device is analyzed using a generalized efficiency, based on the entropy generation rate. In this model, in order to extract the entropy generation rate and the dissipative terms caused by fluid friction and heat flow in alternate tube, simplified momentum and energy equations are solved analytically and velocity... 

In this article a double-inlet pulse-tube refrigerator (DIPTR) is modeled using the nodal analysis technique. The main complexity of the problem is oscillatory and unsteady characteristics of the flow. Solving the flow field in the regenerator section of the system as a porous medium with nonlocal thermal equilibrium is challenging. Governing equations are developed applying mass, energy, and momentum equations to different finite volumes in each component of DIPTR. A numerical code (SharifPTR), with graphical user interface, has been developed to investigate the influence of geometrical and working parameters on performance. The governing equations are a system of boundary value problems.... 

Double-inlet pulse tube refrigerators are one of the most common types of cryocoolers. There are several advantages of double-inlet pulse tube refrigerators, such as not having moving parts, reliability, and long life. Double-inlet pulse tube refrigerators have been used in several applications such as cooling the semiconductors, infrared sensors, and astronomical detectors. In the recent decade, several research efforts have been performed to investigate double-inlet pulse tube refrigerators. Generally, most of them are experimental or numerical, and the recent literature survey shows there is not an analytical solution for the complete system of a double-inlet pulse tube refrigerator,... 

The objective of the present work is to compare the performance of the regenerator of pulse tube refrigerators at low and high frequencies. The hydrodynamic and thermal behavior of the regenerator is investigated in this respect. To consider the system performance, a system of conservation equations including two energy equations for the regenerator as a porous media is employed. The present model considers one-dimensional, periodic, unsteady, compressible flow in the regenerator. The conservation equations are transformed by implementing the volumetric average scheme. The method of harmonic approximation is employed to derive an analytical solution. To explore the system performance, net... 

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... 

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 with 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 DIPTR is modeled applying the nodal analysis technique, using mass, momentum and energy conservation equations. The model is able to compute instantaneous flow field throughout the system and calculate cooling capacity... 

The objective of the present work is to analyze the performance of the regenerator of pulse tube refrigerators. Hydrodynamic and thermal behavior of the regenerator is investigated in this respect. To consider the system performance, a system of conservation equations including two energy equations for the regenerator as a porous media is employed. The present model considers one dimensional periodic unsteady compressible flow in the regenerator. The conservation equations are transformed by implementing the volumetric average scheme. Method of harmonic approximation is employed to derive an analytical solution. To explore the system performance, net energy flow and entropy generation...