Cryogenic refrigeration installation and method

Abstract

The invention provides a cryogenic refrigeration installation comprising an enclosure with thermally conductive trays (thermal stages) and plates. A cooling system uses a refrigerator with a helium-based cycle fluid. The cycle circuit incorporates a first storage vessel for liquefied cycle fluid. After initial tray/plate cooling, a first bypass line with an expansion member diverts some cycle fluid to this vessel. Subsequently, the main cycle fluid is cooled by heat exchange with the liquefied fluid in said first vessel before further tray/plate cooling. A key feature is a second bypass line within the enclosure, which further expands a portion of this pre-cooled cycle fluid. This expansion generates an even colder flow (e.g., 1 K to 2 K) to cool an additional tray or plate, facilitating efficient multi-temperature cryogenic cooling.

1 . A cryogenic refrigeration installation comprising:
 an enclosure delimiting a sealed volume closed by a cover, the enclosure accommodating at least two thermally conductive trays distributed in a distribution direction in the enclosure and forming thermal stages, at least one of the two thermally conductive trays being connected to a heat shield forming a thermal insulation volume;   a cooling system configured to cool to a cryogenic temperature by cooling at least some of the thermally conductive trays and/or one or more plate(s) connected to the thermally conductive trays and forming a support for a set of cable(s) or samples to be cooled,   wherein the cooling system comprises a refrigerator that is configured to perform a refrigeration cycle on a cycle fluid, said refrigerator comprising a cycle circuit containing a cycle fluid comprising helium, the cycle circuit being configured to subject the cycle fluid to a thermodynamic cycle bringing the cycle fluid at at least a cold end of the cycle circuit to a determined cold temperature, the cycle circuit placing a flow of cycle fluid at the cold end in heat exchange with at least some of the thermally conductive trays and/or plates,   wherein the cycle circuit further comprises a compression mechanism configured to compress the cycle fluid, a cooling member configured to cool the cycle fluid, an expansion mechanism configured to expand the cycle fluid and a heating member configured to heat the expanded cycle fluid,   wherein the cycle circuit further comprises:
 a first storage vessel configured to store a reserve of liquefied cycle fluid; 
 downstream of the heat exchange with at least some thermally conductive trays and/or plates; 
 a bypass line configured to divert at least some of the flow of cycle fluid to the first storage vessel, the bypass line comprising a bypass expansion member configured to expand the flow of cycle gas before feeding the first storage vessel; 
 upstream of the heat exchange with at least some thermally conductive trays and/or plates, a portion in heat exchange with the liquefied cycle fluid contained in the first storage vessel; 
 downstream of the passage inside the first storage vessel, at least one first line located in the enclosure exchanging heat with at least some thermally conductive trays and/or plates; and 
 a second bypass line for the first line, the second bypass line being located in the enclosure and provided with a second bypass expansion member configured to expand the cycle fluid in order to produce a colder flow of bypass cycle fluid at a temperature of between 1 and 2 K, said bypass cycle fluid being placed in heat exchange with at least one additional thermally conductive tray or plate of the installation. 
   
     
     
         2 . The installation according to  claim 1 , wherein the cycle circuit comprises, downstream of the heat exchange with the additional tray or plate, a line for returning the bypass cycle fluid to the mechanism for compressing the cycle fluid. 
     
     
         3 . The installation according to  claim 1 , wherein the return line directs the bypass cycle fluid to the inlet of a dedicated compressor of the mechanism for compressing the cycle fluid, which is arranged in series upstream of the mechanism for compressing the rest of the cycle fluid. 
     
     
         4 . The installation according to  claim 2 , wherein the cycle circuit comprises a portion for heat exchange between the return line and a cycle circuit line that feeds some trays and/or plates. 
     
     
         5 . The installation according to  claim 2 , wherein the cycle circuit comprises, downstream of the heat exchange with the additional tray or plate, a line for transferring the bypass cycle fluid to the first storage vessel. 
     
     
         6 . The installation according to  claim 5 , wherein the cycle circuit comprises a portion for heat exchange between the line for transferring the bypass cycle fluid and a cycle circuit line that feeds some trays and/or plates. 
     
     
         7 . The installation according to  claim 1 , wherein the cycle circuit comprises, downstream of the heat exchange with at least some trays and/or plates, a return line that is configured to return, to the compression mechanism, the fraction of the flow of cycle fluid that has not been diverted to the first storage vessel. 
     
     
         8 . The installation according to  claim 1 , wherein the cycle circuit comprises a return line connecting an outlet of the first storage vessel to the compression mechanism. 
     
     
         9 . The installation according to  claim 8 , wherein the return line comprises a cryogenic compressor or pump. 
     
     
         10 . The installation according to  claim 1 , wherein the cycle circuit of the refrigerator comprises a plurality of distinct lines that place different flows of cycle fluid in heat exchange with distinct trays and/or plates. 
     
     
         11 . The installation according to  claim 1 , wherein the cycle circuit comprises at least one line that places the cycle fluid in heat exchange in series with a plurality of distinct trays and/or plates of the same enclosure and/or of a plurality of distinct enclosures. 
     
     
         12 . The installation according to  claim 1 , wherein the cycle circuit is configured to subject the cycle fluid to a thermodynamic cycle bringing the cycle fluid to a plurality of distinct cold temperatures at a plurality of cold ends of the cycle circuit, respectively, the cycle circuit of the refrigerator comprising a plurality of distinct lines that place different flows of cycle fluid at different temperatures in heat exchange in parallel with respective distinct trays and/or plates. 
     
     
         13 . A refrigeration method comprising the steps of:
 providing the installation as claimed in  claim 1 ;   producing a cooling power determined by the refrigerator, using some of this cooling power produced to cool a set of thermally conductive tray(s) and/or plate(s) through heat exchange with a flow of cycle fluid;   recovering this flow of cycle fluid after heat exchange;   expanding a fraction of said flow of cycle fluid recovered to the first storage vessel in order to form a reserve of cold; and   cooling the flow of cycle fluid using the cycle fluid from the first storage vessel.   
     
     
         14 . The method according to  claim 13 , further comprising a step of cooling the cycle fluid through heat exchange with the liquefied cycle fluid contained in the first storage vessel, a step of cooling at least some trays and/or plates to a first temperature using a first fraction of this cooled cycle fluid, the method comprising a step of expanding, in the enclosure, a second fraction of this cooled cycle fluid, this second fraction of cycle fluid being used to cool at least one tray and/or plates to a second temperature that is lower than the first temperature.