Dilution refrigeration device

Abstract

The invention relates to a dilution refrigeration device for obtaining very low temperatures, in particular in the range comprised between one millikelvin and one hundred millikelvins, comprising a looped working circuit containing a cycle fluid comprising a mixture of helium isotope 3 and helium isotope 4, the working circuit comprising a first set of pipes that includes, between a mixing chamber and a boiler, a first portion having a plurality of first pipe branches arranged in parallel, subdividing a cycle flow into a plurality of parallel flows, and in that a second set of pipes comprises, between the boiler and the mixing chamber, a second portion of a plurality of second pipe branches arranged in parallel, subdividing the cycle flow into a plurality of parallel flows, and in that the first heat exchange section comprises a plurality of counterflow heat exchangers each providing heat exchange between a first pipe branch of the first portion and a second pipe branch of the second portion.

1 . A dilution refrigeration device for achieving very low temperatures, in particular in the range between one millikelvin and around one hundred millikelvin, comprising a working circuit ( 20 ) in the form of a loop containing a cycle fluid comprising a mixture of helium-3 (3He) and helium-4 (4He), the working circuit ( 20 ) comprising a mixing chamber ( 3 ), a boiler ( 5 ) and a transfer member ( 6 ), which are arranged in series and fluidically connected via a first set of pipes ( 2 ,  12 ,  4 ), the first set of pipes ( 2 ,  12 ,  4 ) being configured to transfer cycle fluid from an outlet of the mixing chamber ( 3 ) to an inlet of the boiler ( 5 ) and from an outlet of the boiler ( 5 ) to an inlet of the transfer member ( 6 ), the working circuit ( 20 ) comprising a second set of pipes ( 7 ,  17 ) connecting an outlet of the transfer member ( 6 ) to an inlet of the mixing chamber ( 3 ), the working circuit ( 20 ) comprising at least a first section ( 9 ) for heat exchange between at least some of the first set of pipes ( 2 ,  12 ) and the second set of pipes ( 7 ,  17 ), the first heat exchange section ( 9 ) comprising a set of one or more heat exchangers ( 5 ) and being situated between the boiler ( 5 ) and the mixing chamber ( 3 ), characterized in that the first set of pipes comprises, between the mixing chamber ( 3 ) and the boiler ( 5 ), a first portion with a plurality of first pipe branches ( 12 ) that are arranged in parallel and subdivide the cycle flow into a plurality of parallel flows, and in that the second set of pipes comprises, between the boiler ( 5 ) and the mixing chamber ( 3 ), a second portion with a plurality of second pipe branches ( 17 ) that are arranged in parallel and subdivide the cycle flow into a plurality of parallel flows, and in that the first heat exchange section ( 9 ) comprises a plurality of counter-current heat exchangers ( 19 ,  29 ), each ensuring heat exchange between a first pipe branch ( 12 ) of the first portion and a second pipe branch ( 17 ) of the second portion. 
     
     
         2 . The device as claimed in  claim 1 , characterized in that the working circuit ( 20 ) has as many first pipe branches ( 12 ) arranged in parallel as second pipe branches ( 17 ) arranged in parallel. 
     
     
         3 . The device as claimed in  claim 1 or 2 , characterized in that each first pipe branch ( 12 ) is in heat exchange with a second pipe branch ( 17 ) in at least one counter-current heat exchanger ( 19 ,  29 ). 
     
     
         4 . The device as claimed in any one of  claims 1 to 3 , characterized in that each first pipe branch ( 12 ) is in heat exchange with a second pipe branch ( 17 ) in a respective group of a plurality of separate counter-current heat exchangers ( 19 ,  29 ) arranged in series in the circuit ( 20 ). 
     
     
         5 . The device as claimed in any one of  claims 1 to 4 , characterized in that the first portion comprises two, three or more than three first pipe branches ( 12 ) arranged in parallel. 
     
     
         6 . The device as claimed in any one of  claims 1 to 5 , characterized in that the second portion comprises two, three or more than three second pipe branches ( 17 ) arranged in parallel. 
     
     
         7 . The device as claimed in any one of  claims 1 to 6 , characterized in that the first heat exchange section ( 9 ) comprises two, three, four, five or more than five separate counter-current heat exchangers ( 19 ,  29 ) arranged in series in the circuit ( 20 ), each ensuring heat exchange between a first pipe branch and a second pipe branch. 
     
     
         8 . The device as claimed in any one of  claims 1 to 7 , characterized in that the upstream ends of the first pipe branches ( 12 ) of the first portion are connected to the same mixing chamber ( 3 ). 
     
     
         9 . The device as claimed in any one of  claims 1 to 8 , characterized in that the downstream ends of the second pipe branches ( 17 ) of the second portion are connected to the same mixing chamber ( 3 ). 
     
     
         10 . The device as claimed in any one of  claims 1 to 9 , characterized in that it comprises a thermally insulated enclosure ( 30 ) that contains the cryogenic cold parts of the device and in particular the first heat exchange section ( 9 ). 
     
     
         11 . The device as claimed in  claim 10 , characterized in that the enclosure ( 30 ) has a cylindrical overall shape extending in a vertical direction, and in that the counter-current heat exchangers ( 19 ,  29 ) are arranged in horizontal planes and distributed vertically, the heat exchangers ( 19 ,  29 ) being fluidically connected to one another via pipework ( 13 ). 
     
     
         12 . The device as claimed in  claims 4 and 11  considered in combination, characterized in that it comprises a plurality of groups of separate counter-current heat exchangers ( 19 ,  29 ) arranged in series in the circuit ( 20 ). 
     
     
         13 . The device as claimed in  claim 12 , characterized in that at least some of the heat exchangers ( 19 ,  29 ) of each of the groups are arranged substantially horizontally, at least two groups of exchangers being arranged adjacently and extending along separate respective vertical axes. 
     
     
         14 . The device as claimed in  claim 12 , characterized in that the heat exchangers ( 19 ,  29 ) of at least one group are arranged substantially within the same horizontal plane, the exchangers ( 19 ,  29 ) being distributed in a circular arc and fluidically connected to one another via pipework ( 13 ), which is for example curved. 
     
     
         15 . device as claimed in any one of  claims 12 to 14 , characterized in that at least some of the heat exchangers ( 19 ,  29 ) of a first group of heat exchangers are at least partially interposed between the heat exchangers ( 29 ,  19 ) of an adjacent second group of heat exchangers.