000056758 001__ 56758
000056758 005__ 20161006102711.0
000056758 0247_ $$2doi$$ahttp://dx.doi.org/10.1103/PhysRevApplied.6.024017
000056758 0248_ $$2sideral$$a96196
000056758 037__ $$aART-2016-96196
000056758 041__ $$aeng
000056758 100__ $$0(orcid)0000-0002-5022-5094$$aGabal Lanau, Miguel
000056758 245__ $$aHydrogen-free liquid-helium recovery plants: the solution for low-temperature flow impedance blocking
000056758 260__ $$c2016
000056758 5060_ $$aAccess copy available to the general public$$fUnrestricted
000056758 5203_ $$aThe blocking of fine-capillary tubes used as flow impedances in He4 evaporation cryostats to achieve temperatures below 4.2 K is generally attributed to nitrogen or air impurities entering these tubes from the main bath. The failure of even the most rigorous low-temperature laboratory best practices aimed at eliminating the problem by maintaining the cleanliness of the helium bath and preventing impurities from entering the capillary tubes suggests that a different cause is responsible for the inexplicable reduction of impedance flow. Many low-temperature research laboratories around the world have suffered this nuisance at a considerable financial cost due to the fact that the affected systems have to be warmed to room temperature in order to recover their normal low-temperature operation performance. Here, we propose an underlying physical mechanism responsible for the blockages based upon the freezing of molecular H2 traces present in the liquid-helium bath. Solid H2 accumulates at the impedance low-pressure side, and, after some time, it produces a total impedance blockage. The presence of H2 traces is unavoidable due its occurrence in the natural gas wells where helium is harvested, forcing gas suppliers to specify a lower bound for impurity levels at about 100 ppb even in high-grade helium. In this paper, we present a simple apparatus to detect hydrogen traces present in liquid helium and easily check the quality of the liquid. Finally, we propose a solution to eliminate the hydrogen impurities in small- and large-scale helium recovery plants. The solution has been implemented in several laboratories that previously experienced a chronic occurrence of blocking, eliminating similar occurrences for more than one year.
000056758 536__ $$9info:eu-repo/grantAgreement/ES/MINECO/IPT-2012-0442-420000$$9info:eu-repo/grantAgreement/ES/MINECO/MAT2015-64083-R
000056758 540__ $$9info:eu-repo/semantics/openAccess$$aby$$uhttp://creativecommons.org/licenses/by/3.0/es/
000056758 655_4 $$ainfo:eu-repo/semantics/article$$vinfo:eu-repo/semantics/publishedVersion
000056758 700__ $$0(orcid)0000-0002-5999-341X$$aArauzo García, Ana Belén
000056758 700__ $$0(orcid)0000-0001-7289-5649$$aCamón Lasheras, Agustin Hispanico$$uUniversidad de Zaragoza
000056758 700__ $$aCastrillo, Marta
000056758 700__ $$aGuerrero Domínguez, Enrique
000056758 700__ $$aLozano, María Pilar
000056758 700__ $$0(orcid)0000-0001-9897-6527$$aPina Iritia, María Pilar$$uUniversidad de Zaragoza
000056758 700__ $$0(orcid)0000-0002-7742-9329$$aSesé Monclús, Javier$$uUniversidad de Zaragoza
000056758 700__ $$aSpagna, Stefano
000056758 700__ $$aDiederichs, Jost
000056758 700__ $$aRayner, Grant
000056758 700__ $$aSloan, Jeff
000056758 700__ $$aGalli, Federica
000056758 700__ $$avan der Geest, Wilfred
000056758 700__ $$aHaberstroh, Christoph
000056758 700__ $$aDittmar, Nico
000056758 700__ $$aOca, Arancha
000056758 700__ $$aGrau, Fernando
000056758 700__ $$aFernandes, Adelino
000056758 700__ $$0(orcid)0000-0002-5710-5562$$aRillo Millan, Conrado Miguel$$uUniversidad de Zaragoza
000056758 7102_ $$12003$$2395$$aUniversidad de Zaragoza$$bDepartamento de Física de la Materia Condensada$$cFísica de la Materia Condensada
000056758 7102_ $$15005$$2555$$aUniversidad de Zaragoza$$bDepartamento de Ingeniería Química y Tecnologías del Medio Ambiente$$cIngeniería Química
000056758 773__ $$g6, 024017 [11p.] (2016)$$pPhys. rev. appl.$$tPhysical review applied$$x2331-7019
000056758 8564_ $$s2522292$$uhttps://zaguan.unizar.es/record/56758/files/texto_completo.pdf$$yVersión publicada
000056758 8564_ $$s110771$$uhttps://zaguan.unizar.es/record/56758/files/texto_completo.jpg?subformat=icon$$xicon$$yVersión publicada
000056758 909CO $$ooai:zaguan.unizar.es:56758$$particulos$$pdriver
000056758 951__ $$a2016-09-28-14:24:08
000056758 980__ $$aARTICLE