Thermal Regulation Passive Device with Micro Capillary Pumped Fluid Loop

Abstract

The device includes an evaporator and a condenser connected by an outer tube in which extends at least one inner tube having one end leading into the condenser and another end connected to an end of a central duct for collecting the vapours of a heat-carrier fluid, in a microporous mass provided in the outer tube and pumping by capillarity the liquid-phase fluid flowing in at least one outer duct between the outer and inner tubes from the condenser to the evaporator, while the vapour-phase fluid flows from the evaporator to the condenser in at least one inner duct inside said at least one inner tube. The invention can be used for the thermal energy transfer from an electronic component or circuit in relation with the evaporator to a cold source in relation with the condenser.

1 . A passive thermal regulation device, comprising at least one heat transfer loop with capillary pumping of a heat-carrier fluid, said loop comprising an evaporator having a microporous mass, and a condenser, for being in heat exchange relationship with a heat source and a cold source respectively, and tubing connecting said evaporator to said the condenser and transporting said heat-carrier fluid essentially in vapour phase from said evaporator to said condenser and essentially in liquid phase from said condenser to said evaporator, said tubing comprising an outer tube, housing said microporous mass having a substantially elongated shape and, ensuring a flow of said liquid-phase heat-carrier fluid by capillary pumping, wherein said liquid phase of said fluid is pumped by at least one end of said microporous mass which is facing said condenser, and flows in at least one outer duct delimited between said outer tube and at least one inner tube extending within said outer tube, and said vapour phase of said fluid heated in said microporous mass of said evaporator is collected in a longitudinal central duct made in said microporous mass and discharged by at least one inner duct delimited within said at least one inner tube, said at least one inner tube being connected by one end to an end of said central duct, while said vapour phase is discharged at an other end of said at least one inner tube, at said condenser. 
     
     
         2 . The device according to  claim 1 , wherein said outer tube is closed on itself, forming a continuous loop, two substantially opposite portions of said outer tube, in relation to a centre of said loop, are in heat exchange relationship, one portion with said condenser and the other portion with said evaporator and with said microporous mass housed in said other portion of said outer tube, and passed through over an entire length of said microporous mass by said central duct, two inner tubes extending within said outer tube, each of said two inner tubes being connected, by a first end, with one of two ends of said central duct of said microporous mass respectively, while a second end of each inner tube opens out into said condenser opposite said second end of the other inner tube so as to connect an inner vapour-phase fluid duct delimited within each inner tube to said at least one outer duct of liquid-phase fluid flowing from said condenser towards a corresponding end face of said microporous mass. 
     
     
         3 . The device according to  claim 1 , wherein said outer tube is closed at both ends which are in a heat exchange relationship, one with said condenser, and the other with said evaporator ( 22 ) and with said microporous mass housed in said other end of said outer tube, said liquid phase of said fluid is pumped by said one end of said microporous mass facing said condenser, and flows in said outer duct delimited between said outer tube and said inner tube extending within said outer tube, and said vapour phase of said fluid heated in said microporous mass of said evaporator is collected in a longitudinal central duct made in said microporous mass and discharged by said the inner duct delimited within said inner tube, said inner tube being connected by one end to one end of said central duct, while said vapour phase is discharged at said other end of said inner tube, at said condenser. 
     
     
         4 . The device according to  claim 1 , wherein said other end of said at least one inner tube located at the level of said condenser is fitted into an annular microporous mass filling a space delimited within said condenser between said other end of said inner tube and said outer tube. 
     
     
         5 . The device according to  claim 4 , wherein liquid condensing in said condenser is drained to said annular microporous mass, by at least one of a capillary drain and a microporous mass located along a wall of said outer tube at said condenser. 
     
     
         6 . The device according to  claim 1 , wherein each of said evaporator and condenser comprises at least one outer sleeve made from a good heat conducting material, said at least one sleeve of said evaporator surrounding at least partially, a portion of said outer tube that houses said microporous mass and said at least one sleeve of said condenser surrounding a portion of said outer tube in which said at least one inner duct releases said vapour-phase fluid towards said at least one outer duct. 
     
     
         7 . The device according to  claim 6 , wherein said at least one outer sleeves comprises at least one base plate made from a good heat conducting material whereby said sleeve is intended to be placed in heat exchange relationship with one of a hot and cold source. 
     
     
         8 . The device according to  claim 1 , wherein said at least one inner tube has walls made from at least one thermally insulating material. 
     
     
         9 . The device according to  claim 1 , wherein said at least one inner tube for discharging said vapour extends into said microporous mass. 
     
     
         10 . The device according to  claim 9 , wherein said at least one inner tube has an outer wall comprising at least one capillary drain defined by at least one groove, arranged at least on a portion of said inner tube that extends into said microporous mass, so as to convey said liquid phase deep within said microporous mass by capillarity. 
     
     
         11 . The device according to  claim 1 , wherein said at least one inner tube has an outer wall comprising capillary drains defined for example by grooves, said capillary drains extending over the entire length of said tube. 
     
     
         12 . The device according to  claim 1 , wherein apart from said microporous mass, an outer wall of said at least one inner tube is in contact with an inner wall of said outer tube, except at the level of at least one capillary drain defining at least one outer duct conveying said liquid phase of said fluid. 
     
     
         13 . The device according to  claim 1 , wherein said microporous mass has a substantially cylindrical outer shape, together with a portion of said outer tube that houses said microporous mass without radial play. 
     
     
         14 . The device according to  claim 1 , wherein said evaporator has an area intended to be in heat exchange contact with said heat source and one dimension of said area along an axis of said outer tube is significantly smaller than a length of said microporous mass. 
     
     
         15 . The device according to  claim 14 , wherein said microporous mass has a diameter and a length that is substantially 2 to 15 times greater than said diameter. 
     
     
         16 . The device according to  claim 1 , wherein said outer tube is in heat exchange contact with said microporous mass over an outer surface of said mass apart from at least one of longitudinal end surfaces of said mass. 
     
     
         17 . The device according to  claim 1 , wherein said outer tube has a cross-section with a constant diameter. 
     
     
         18 . The device according to  claim 1 , wherein said outer tube is made from a good heat conducting material, at least in a first portion of said outer tube that is in heat exchange relationship with said microporous mass, and in a second portion of said outer tube in heat exchange relationship with said condenser or constituting said condenser. 
     
     
         19 . The device according to  claim 18 , wherein said outer tube is metal, preferably stainless steel. 
     
     
         20 . The device according to  claim 1 , wherein said outer tube and said at least one inner tube are cylindrical with a circular cross-section, said at least one inner tube having a diameter which is substantially half of a diameter of said outer tube. 
     
     
         21 . The application of a passive thermal regulation device with at least one heat transfer loop according to  claim 1 , to the transfer of thermal energy from a heat source, such as an electronic component or set of components, in heat exchange relationship with the evaporator, to a cold source, in heat exchange relationship with the condenser. 
     
     
         22 . A method for transferring thermal energy from a heat source to a cold source with a passive thermal regulation device having at least one heat transfer loop, including a step of using a heat transfer loop with capillary pumping of a heat-carrier fluid, said loop comprising an evaporator having a microporous mass, and a condenser, and arranging said evaporator and condenser in heat exchange relationship with a heat source and a cold source respectively, and tubing connecting said evaporator to said condenser and transporting said heat-carrier fluid essentially in vapour phase from said evaporator to said condenser and essentially in liquid phase from said condenser to said evaporator, said tubing comprising an outer tube, housing said microporous mass having a substantially elongated shape and, ensuring a flow of said liquid-phase heat-carrier fluid by capillary pumping, wherein said liquid phase of said fluid is pumped by at least one end of said microporous mass which is facing said condenser, and flows in at least one outer duct delimited between said outer tube and at least one inner tube extending within said outer tube, and said vapour phase of said fluid heated in said microporous mass of said evaporator is collected in a longitudinal central duct made in said microporous mass and discharged by at least one inner duct delimited within said at least one inner tube, said at least one inner tube being connected by one end to an end of said central duct, while said vapour phase is discharged at an other end of said at least one inner tube, at said condenser.