Alain Ravex

Permanent flow in low and high frequency pulse tube coolers – experimental results

This paper describes the experiments performed at CEA/SBT on pulse tube coolers to demonstrate the effects of the permanent flow in the double inlet configuration. This permanent flow affects the wall temperature profiles of the regenerator and the tube. Solutions to minimise it have been tested and have led to a significant gain in performance. Experiments have been performed on different pulse tubes at low and high frequencies.

The 300 W — 1.75 K Tore Supra Refrigerator Cold Centrifugal Compressors Report

The cold centrifugal compressors which are part of the TORE SUPRA refrigerator were designed and manufactured by L’AIR LIQUIDE. They were tested at nominal conditions on a special test rig. The refrigerator is now installed and all acceptance tests have been completed. Other tests were carried out off design conditions with the machines installed in the TORE SUPRA refrigerator.

Performance testing of a large heat lift 40 to 80K pulse tube cooler for space applications

A Large heat lift 40 to 80K Pulse Tube Cooler (LPTC) has been designed, manufactured and tested in partnership between AL/DTA, CEA/SBT and THALES Cryogenics BV. The Engineering Model specification of 2.3 W cooling power at 50 K for 10°C rejection temperature and maximum 160 watts electrical input power has been reached. The as built model weighs 5.13 kg. The thermal and mechanical performances are presented and discussed. This work is funded by the European Space Agency (ESA/ESTEC Contract N°18433/04/NL/AR) in the frame of future Earth Observation instruments development.

Developments on Single and Double Stage GM Type Pulse Tube Cryorefrigerators

Pulse tube (PT) cryocoolers with no moving parts in their cold ends are potentially able to replace conventional Gifford MacMahon (GM) cryocoolers for most applications. Over the past several years, CEA/SBT has undertaken basic research and prototype development of GM driven PT cryocoolers. Systematic studies have been carried out to characterize flow distribution and d.c. flow effects. Based on a good comprehension of these phenomena, several prototypes have been built and optimized for various customised applications. Their performance is presented in this paper.

Closed cycle liquid helium refrigerators

Abstract We have developed closed cycle liquid helium refrigerators using a Joule Thomson circuit precooled by commercially available two staged Gifford Mac Mahon cryocoolers. The Joule Thomson counterflow heat exchangers are modular and have been thermo-hydraulically characterized. Fully automatic cool down and operation are achieved by two pneumatically driven by pass and expansion valves. Several apparatus have been built or are under assembly with cooling power ranging from 100 mW up to 5 Watt, for temperature ranging from 2.8 K up to 4.5 K. A trouble free operation with several warm up and cool down cycles has been proven over 7000 hours.

Cryocoolers Development and Integration for Space Applications at Air Liquide

Publisher Summary This chapter reviews cooling technologies and presents the main characteristics and performances of these coolers. Air Liquide Division Techniques Avancees (AL/DTA) has been involved in space cryogenics since several decades in the framework of the European ARIANE program mainly for the launcher liquid cryogens (LH2 and LOx) tanks development, qualification, and manufacturing but also for the design and implementation of the liquefaction, storage and distribution infrastructures on the launching pad at Kourou, Guyana. More recently AL/DTA has extended its space related business by developing and integrating cryocoolers for use onboard the International Space Station (ISS) or to be flown on scientific or commercial satellites payloads. Several technologies, including Brayton, Joule Thomson, Stirling, Pulse Tube and Dilution refrigeration cycles, have been demonstrated. Some of these coolers have been specifically designed and developed to be integrated within ESA or NASA scientific missions (MELFI, CRYOSYSTEM, PLANCK/HFI) to be flown during the next coming years. Space qualification of these coolers has been already achieved or is going on. Development of miniature Brayton and large cooling capacity pulse tube coolers have also been initiated to prepare the next generation of AL/DTA space coolers.

Large cooling power hybrid Gifford mac Mahon / Joule Thomson refrigerator andliquefier

Abstract In this paper, we present two refrigerators using Joule Thomson cycle providing cooling powers of 4.5 W at 4.4 K and using Gifford Mac Mahon cryocoolers for the precooling. Several smaller machines have been developped in our laboratory with refrigeration capacity ranging from 100 mW up to 1.5 W in the temperature range 3 K to 4.4 K. In the present case, to increase the cooling power, we introduced a three stage precooling scheme using a liquid nitrogen vessel plus the two stages of a Gifford Mac Mahon cryocooler. Cooldown and operation of the system are fully automatic. The first refrigerator is used to cool two Nb 3 Sn superconducting coils having a maximum field of 11.8 T. The second system is an helium liquefier, designed to produce more than 1 liter per hour.