Performance Of Pulse Tube Cooler Research Articles

Investigation on a two-stage pulse tube cooler at liquid hydrogen temperature using independent displacer phase shifter

Phase shifter plays an important role in affecting cooling performance of pulse tube cooler (PTC). Warm displacer has been considered a very promising phase shifter due to phase shifting ability and work recovery. Independent displacer phase shifter (IDPS) for two stage PTC is purposed in this paper. Based on a two stage PTC, IDPS and a stepped displacer phase shifter (SDPS) have been comparatively investigated. Firstly, the phase shifting mechanism of two type displacers was studied. Numerical simulation was then conducted to investigated the effect of spring stiffness, moving mass and mechanical damper, and the optimal parameters of SDPS and IDPS were obtained. A cooling power of 1.8 W at 20 K was obtained with 220 W acoustic power input using IDPS, which is 16.9 % higher than that of SDPS. Next, Axial distributions of the phase difference and acoustic power were presented and discussed. In addition, exergy losses in each component were compared. IDPS presented the potential of achieving a higher cooling efficiency at lower temperature stage.

Experimental study of the influence of cold heat exchanger geometry on the performance of a co-axial pulse tube cooler

Improving the performance of the pulse tube cooler is one of the important objectives of the current studies. Besides the phase shifters and regenerators, heat exchangers also play an important role in determining the system efficiency and cooling capacity. A series of experiments on a 10W @ 77K class co-axial type pulse tube cooler with different cold heat exchanger geometries are presented in this paper. The cold heat exchangers are made from a copper block with radial slots, cut through using electrical discharge machining. Different slot widths varying from 0.12mm to 0.4mm and different slot numbers varying from around 20–60 are investigated, while the length of cold heat exchangers are kept the same. The cold heat exchanger geometry is classified into three groups, namely, constant heat transfer area, constant porosity and constant slot width. The study reveals that a large channel width of 0.4mm (about ten times the thermal penetration depth of helium gas at 77K, 100Hz and 3.5MPa) shows poor performance, the other results show complicated interaction effects between slot width and slot number. These systematic comparison experiments provide a useful reference for selecting a cold heat exchanger geometry in a practical cooler.

Regenerator performance improvement of a single-stage pulse tube cooler reached 11.1 K

In order to improve the cooling performance of pulse tube cooler (PTC) at 20–40 K, hybrid regenerators are often employed. In this paper a three-layer regenerator, which consists of woven wire screen, lead sphere and Er 3Ni is optimized to enhance the cooling performance and explore the lowest attainable refrigeration temperature for a single-stage PTC. The efforts focus on the temperature range of 80–300 K, where woven wire screens are used. Theoretical and experimental studies are carried out to study the metal material and the mesh size effect of woven wire screens on the performance of the single-stage G-M type PTC. A lowest no-load refrigeration temperature of 11.1 K was obtained with an input power of 6 kW. The PTC can supply 17.8 W at 20 K and 39.4 W at 30 K, respectively.

Effects of reservoir volume on performance of pulse tube cooler

A pulse tube cooler has the advantages of long-life and low-vibration over conventional cryocoolers such as G-M and Stirling coolers because of the absence of moving parts at low temperature. On the other hand, the combination of a reservoir and orifice is indispensable to optimize the performance of pulse tube coolers. In order to make the pulse tube cooler compact for practical applications, the volume of reservoir should be minimized. This paper analyzes the effects of the reservoir volume on the thermodynamic performance of various components in a simple orifice and a double-inlet pulse tube cooler by combining a linearized model with a thermodynamic analysis. Expressions of entropy production for those components are presented. The results show that the reservoir volume has a significant influence on the entropy production in the various components when the reservoir to pulse tube volume ratio is smaller than about 5. The ratio is important to determine the minimum reservoir volume for a pulse tube cooler. Optimum settings for a double-inlet pulse tube cooler are also discussed.