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Enschede, Netherlands

Derking J.H.,University of Twente | Holland H.J.,University of Twente | Lerou P.P.P.M.,Kryoz Technologies BV | Tirolien T.,European Space Agency | Ter Brake H.J.M.,University of Twente
International Journal of Refrigeration | Year: 2012

Micromachined Joule-Thomson (JT) coolers can be used for cooling small electronic devices. For this application, two types of micromachined JT cold stages with dimensions of 60.0 × 10.0 × 0.7 mm 3 were developed and tested that were designed for operation with nitrogen at 100 K. A theoretical analysis is developed to investigate the application of these cold stages in the temperature range 80-250 K. This analysis shows that the cold stages can be operated with various working fluids. Experiments of both JT cold stages operating with nitrogen and methane as working fluids were done to validate this analysis. The cooling power and the temperature profile along the length of the counter-flow heat exchanger were measured. In this paper, the theoretical analysis is described and the measuring results are presented and discussed. © 2012 Elsevier Ltd and IIR. All rights reserved. Source

Benthem B.,Dutch Space B V | Doornink J.,Dutch Space B V | Boom E.,Dutch Space B V | Holland H.J.,University of Twente | And 3 more authors.
Cryogenics | Year: 2015

A sorption cooler uses the Joule-Thomson effect for cooling a gas by expanding it through a flow restriction. The flow of gas is sustained by a compressor consisting of one or more sorption cells, which cyclically adsorb and desorb gas according to the fully reversible process of physical sorption. The technology has been shown to provide active cooling in the cryogenic temperature range without exporting vibrations or electromagnetic interference. Due to full reversibility of the process and the absence of moving parts (apart from check valves, which open and close with a very low frequency), such a cooler has the potential for a very long life and high reliability. This paper starts with a recapitulation of the principles of physical sorption cooling followed by an overview of the strengths and weaknesses of the technology in relation to other space cooling technologies, such as pulse-tube cooling and Stirling cooling. Next, the present status of physical sorption cooling technology is presented based on developments previously and currently being performed by the University of Twente, Dutch Space and Kryoz Technologies. A summary will be given of the various existing demonstrator- and lab-models which have been built, along with an overview of the tests which have so far been performed. The central result of this paper is an assessment of the current Technology Readiness Level (TRL) of various sorption cooler configurations, along with their application range in terms of temperatures, heat loads and mission profile. Finally, an outline is given on the way forward currently being pursued by the developers to achieve full maturity of the technology. ©2014 Elsevier Ltd. All rights reserved. Source

Cao H.S.,University of Twente | Holland H.J.,University of Twente | Vermeer C.H.,University of Twente | Vanapalli S.,University of Twente | And 3 more authors.
Journal of Micromechanics and Microengineering | Year: 2013

Micromachined cryocoolers are attractive tools for cooling electronic chips and devices to cryogenic temperatures. A two-stage 30 K microcooler operating with nitrogen and hydrogen gas is fabricated using micromachining technology. The nitrogen and hydrogen stages cool down to about 94 and 30 K, respectively, using Joule-Thomson expansion in a restriction with a height of 1.10 μm. The nitrogen stage is typically operated between 1.1 bar at the low-pressure side and 85.1 bar at the high-pressure side. The hydrogen stage has a low pressure of 5.7 bar, whereas the high pressure is varied between 45.5 and 60.4 bar. In changing the pressure settings, the cooling power can more or less be exchanged between the two stages. These typically range from 21 to 84 mW at 95 K at the nitrogen stage, corresponding to 30 to 5 mW at 31-32 K at the hydrogen stage. This paper discusses the characterization of this two-stage microcooler. Experimental results on cool down and cooling power are compared to dynamic modeling predictions. © 2013 IOP Publishing Ltd. Source

Cao H.S.,University of Twente | Holland H.J.,University of Twente | Vermeer C.H.,University of Twente | Vanapalli S.,University of Twente | And 3 more authors.
Journal of Micromechanics and Microengineering | Year: 2013

Cryogenic temperatures are required for improving the performance of electronic devices and for operating superconducting sensors and circuits. The broad implementation of cooling these devices has long been constrained by the availability of reliable and low cost cryocoolers. After the successful development of single-stage micromachined coolers able to cool to 100 K, we now present a micromachined two-stage microcooler that cools down to 30 K from an ambient temperature of 295 K. The first stage of the microcooler operates at about 94 K with nitrogen gas and pre-cools the second stage operating with hydrogen gas. The microcooler is made from just three glass wafers and operates with modest high-pressure gases and without moving parts facilitating high yield fabrication of these microcoolers. We have successfully cooled a YBCO film through its superconducting transition state to demonstrate a load on the microcooler at cryogenic temperatures. This work could expedite the application of superconducting and electronic sensors and detectors among others in medical and space applications. © 2013 IOP Publishing Ltd. Source

Kryoz Technologies B.V. | Date: 2011-10-03

Micro-cooling device comprising:an elongate body having a first end and an opposite second end;an evaporation chamber arranged at the first end of the elongate body;a feed channel arranged between a feed opening, for feeding a high pressure cooling medium, at the second end of the elongate body and the evaporation chamber;a discharge channel arranged between the evaporation chamber and a discharge opening at the second end of the elongate body;a restriction arranged in the feed channel and adjacent to the evaporation chamber;temperature equalization means for equalizing the temperature over a isothermal zone extending from the first end to a first zone of the feed channel upstream of the restriction.

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