Performance of large-scale helium refrigerators subjected to pulsed heat load from fusion devices
by Rohan Dutta
Rohan Dutta, Parthasarathi Ghosh, Kanchan Chowdhury
Cryogenic Engineering Centre, Indian Institute of Technology Kharagpur, India
Presented in 24th International Cryogenic Engineering Conference-International Cryogenic Materials Conference 2012, Fukuoka, Japan, May 14-18, 2012
Immediate effects of pulsed heat load from fusion devices in helium refrigerators are wide variations of mass flow... more Immediate effects of pulsed heat load from fusion devices in helium refrigerators are wide variations of mass flow rate of low pressure stream returning to cold-box of the refrigerators. In this paper, using quasi steady and dynamic simulations in Aspen HYSYS® a four expander based modified Claude cycle has been analyzed to identify the critical equipment that may be affected due to such flow rate fluctuations at the return stream and their transient performance. Suitable techniques for mitigation of fluctuation of return stream have been explored from the open literature in order to find out operability of these plants.
Performance of large-scale helium refrigerators subjected to pulsed heat load from fusion devices
by Rohan Dutta
Rohan Dutta, Parthasarathi Ghosh, Kanchan Chowdhury
Cryogenic Engineering Centre, Indian Institute of Technology Kharagpur, India
Presented in 24th International Cryogenic Engineering Conference-International Cryogenic Materials Conference 2012, Fukuoka, Japan, May 14-18, 2012
Immediate effects of pulsed heat load from fusion devices in helium refrigerators are wide variations of mass flow... more Immediate effects of pulsed heat load from fusion devices in helium refrigerators are wide variations of mass flow rate of low pressure stream returning to cold-box of the refrigerators. In this paper, using quasi steady and dynamic simulations in Aspen HYSYS® a four expander based modified Claude cycle has been analyzed to identify the critical equipment that may be affected due to such flow rate fluctuations at the return stream and their transient performance. Suitable techniques for mitigation of fluctuation of return stream have been explored from the open literature in order to find out operability of these plants.
Experimental analysis of free warm expander pulse tube
published Cryogenics 2001
In this paper we report on the development of a prototype of a miniature free warm expander pulse tube (FWEPT), a... more In this paper we report on the development of a prototype of a miniature free warm expander pulse tube (FWEPT), a novel configuration of the orifice pulse tube cooler with the orifice and the reservoir replaced by a secondary piston. It is shown that the motion of the secondary piston can be driven with the appropriate amplitude and phase by the pneumatic force of the pressure cycle. Investigation of the loss mechanisms has shown that the dominant contributions to the heat leak are heat conduction through the regenerator mesh and regenerator ineffectiveness loss, and are ultimately related to the fact that the mass flow rate in pulse tube coolers is large due to the relatively large void volume.
Thermodynamic Analysis of Collin’s Cycle: Aspects of Designing Large-scale Helium Liquefiers
Rijo J. Thomas, Ghosh P., Chowdhury K.
Proceedings of International Cryogenic Engineering Conference, ICEC 23, Wroclaw, Poland 2010
Large-scale helium liquefiers have evolved out of basic Collin’s cycle. Though simple, Collin’s cycle has all the... more Large-scale helium liquefiers have evolved out of basic Collin’s cycle. Though simple, Collin’s cycle has all the basic characteristics of large-scale helium liquefiers and the results of its performance analysis may give a fair indication of initial design and configuration choices to be made as well as the expected behavior of large-scale liquefiers. This study, using a commercial simulator Aspen Hysys®, identifies the effects of main process parameters viz. operating pressures, mass flow-rates through expanders, and component efficiencies on the overall performance of Collin’s cycle. Conclusions arising out may provide guidelines for the design of larger and more complicated helium liquefaction plants.
Cryogenic transimpedance amplifier for micromechanical capacitive sensors
by Pedro Julian
"published in 'REVIEW OF SCIENTIFIC INSTRUMENTS' 2008"
We developed a cryogenic transimpedance amplifier that works at a broad range of temperatures,
from room... more
We developed a cryogenic transimpedance amplifier that works at a broad range of temperatures,
from room temperature down to 4 K. The device was realized with a standard complementary metal
oxide semiconductor 1.5 m process. Measurements of current-voltage characteristics, open-loop
gain, input referred noise current, and power consumption are presented as a function of
temperature. The transimpedance amplifier has been successfully applied to sense the motion of a
polysilicon micromechanical oscillator at low temperatures. The whole device is intended to serve
as a magnetometer for microscopic superconducting samples. © 2008 American Institute of Physics.
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