Patent Publication Number: US-2022232735-A1

Title: Heat pipe with multiple stages of cooling

Description:
INTRODUCTION 
     The present disclosure generally relates to electronics cooling, and more particularly relates to a heat pipe with multiple liquids and associated boiling temperatures that are different from one another to provide multiple stages of cooling. 
     Electronics generate heat whenever an electric current flows through them. The amount of heat depends on the power, device characteristics, and circuit design. The resistance of processors, driver circuits, power circuits, and memory contribute to some heat and power losses. To avoid failures or circuit malfunctions, electronics must operate and remain within safe temperature limits. While some circuits will work without additional cooling, there are other circuits that include mechanisms for dissipating heat. 
     Existing heat pipes for electronics include an elongated tube containing a single liquid. The tube has a first end that transfers heat from an electronic component to the liquid, such that the liquid vaporizes into a vapor when the temperature of the liquid reaches its boiling temperature. The heat pipe further includes a second end that transfers heat from the vapor to the surrounding environment for condensing the vapor into the liquid when the temperature of the vapor falls below the boiling temperature. The heat pipe further includes a wick material interconnecting the first and second ends to return the condensed liquid from the second end to the first end. In a dry-out condition when the entire liquid vaporizes into a vapor, the vapor does not move toward the second end to cool and condensate does not form and return to the first end, such that the ability of the heat pipe to cool is adversely affected. 
     Thus, while existing heat pipes achieve their intended purpose, there is a need for a new and improved heat pipe for electronics that addresses these issues. 
     SUMMARY 
     According to several aspects of the present disclosure, a heat pipe is provided for cooling an electronic component of a printed circuit board. The heat pipe includes a tube having an inner diameter surface that defines a bore, with the tube having first and second ends along the bore. The heat pipe further includes a sorbent material coated onto the inner diameter surface of the tube. The heat pipe further includes a first liquid, which is contained within the bore of the tube and has a first boiling temperature. The heat pipe further includes a second liquid, which is adsorbed by the sorbent material and has a second boiling temperature that is higher than the first boiling temperature of the first liquid. The first liquid vaporizes into a first vapor, in response to the tube receiving heat from the electronic component and the first liquid reaching the first boiling temperature. The first vapor flows toward the second end of the tube where the first vapor dissipates heat through the tube and condenses into the first liquid. The second liquid is desorbed from the sorbent material, in response to the second liquid and the sorbent material reaching a predetermined desorption temperature that is less than the second boiling temperature. The second liquid vaporizes into a second vapor, in response to the second liquid reaching the second boiling temperature. 
     In one aspect, the sorbent material is configured to desorb at least a portion of the second liquid into the bore before all of the first liquid vaporizes into the first vapor. 
     In another aspect, the inner diameter surface defines at least one axial groove extending between the first and second ends for drawing the first liquid by capillary action from the second end to the first end. 
     In another aspect, a plurality of axial grooves are spaced circumferentially from one another on the inner diameter surface. 
     In another aspect, the sorbent material is spaced from the second end of the tube, such that the condensed first liquid flows from the bore to the axial grooves. The sorbent material is further spaced from the first end of the tube, such that the first liquid returns from the axial grooves to the bore. 
     In another aspect, the first liquid is water. 
     In another aspect, the second liquid is ethylene glycol. 
     According to several aspects of the present disclosure, an electronics cooling system includes an electronic component that generates heat. The electronics cooling system further includes a heat pipe for cooling the electronic component, and the heat pipe includes a tube having an inner diameter surface that defines a bore. The tube has first and second ends along the bore. The heat pipe further includes a sorbent material coated onto the inner diameter surface of the tube proximal to the first end. The heat pipe further includes a first liquid, which is contained within the bore of the tube and has a first boiling temperature. The heat pipe further includes a second liquid, which is adsorbed by the sorbent material and has a second boiling temperature. The second boiling temperature of the second liquid is higher than the first boiling temperature of the first liquid. The first liquid vaporizes into a first vapor, in response to the first end of the tube receiving heat from the electronic component and the first liquid reaching the first boiling temperature. The first vapor moves toward the second end where the first vapor dissipates heat through the tube and condenses into the first liquid. The second liquid is desorbed from the sorbent material, in response to the second liquid and the sorbent material reaching a predetermined desorption temperature that is less than the second boiling temperature. The second liquid vaporizes into a second vapor, in response to the second liquid reaching the second boiling temperature. The electronics cooling system further includes one or more thermocouples attached to at least one of the electronic component and the heat pipe for generating a first temperature signal associated with a temperature of the first liquid. The electronics cooling system further includes a controller electrically connected to the thermocouple. The controller compares the temperature of the first liquid to a first temperature threshold, in response to the controller receiving the first temperature signal from the thermocouple. The controller generates a first warning notification signal, in response to the controller determining that the temperature of the first liquid is above the first temperature threshold. The controller is electrically coupled to a display device for displaying a first warning indicative of the first liquid approaching the first temperature threshold, in response to the display device receiving the first warning notification signal from the controller. 
     In one aspect, the thermocouple generates a second temperature signal associated with the temperature of the second liquid. The controller compares the temperature of the second liquid to a second temperature threshold, in response to the controller receiving the second temperature signal from the thermocouple. The controller generates a second warning notification signal, in response to the controller determining that the temperature of the second liquid is above the second temperature threshold. The display device displays a second warning indicative of the temperature of the second liquid approaching the second temperature threshold, in response to the display device receiving the second warning notification signal from the controller. 
     In another aspect, the electronics cooling system further includes a fan that generates a flow of air for cooling the second end of the tube and the first vapor within the tube. 
     In another aspect, the electronics cooling system further includes a wick material attached to the inner diameter surface adjacent to the second end of the tube, with the wick material being different from the sorbent material. 
     In another aspect, the wick material is a layer extending from the second end to a portion of the tube that is adjacent to the electronic component. 
     In another aspect, the sorbent material includes a plurality of recesses and the wick material further includes a plurality of protrusions extending from the layer into the recesses of the sorbent material, such that the wick material draws the first liquid from the second end to the first end of the tube. 
     In another aspect, the inner diameter surface defines a plurality of axial grooves extending between the first and second ends for drawing the first liquid by capillary action from the second end to the first end. The axial grooves are spaced circumferentially from one another about the inner diameter surface. 
     In another aspect, the sorbent material is spaced from the second end of the tube, such that the condensed first liquid flows from the bore to the axial grooves. The sorbent material is further spaced from the first end of the tube, such that the first liquid returns from the axial grooves to the bore. 
     In another aspect, the thermocouples include a first thermocouple, which is attached to the electronic component and generates the first temperature signal. The thermocouples further include a second thermocouple, which is attached to the heat pipe and generates the second temperature signal. 
     According to several aspects of the present disclosure, a method of operating an electronics cooling system is provided. The electronics cooling system includes an electronic component and a heat pipe attached to the electronic component. The heat pipe includes a tube having an inner diameter surface defining a bore, a sorbent material coated onto the inner diameter surface, a first liquid contained within the bore, a second liquid adsorbed by the sorbent material, one or more thermocouples attached to at least one of the electronic component and the heat pipe, and a controller. The method includes the step of transferring heat from the electronic component to the first liquid at a first end of the closed ended tube. The first liquid vaporizes into a first vapor, in response to the first liquid receiving heat from the electronic component and the first liquid reaching the first boiling temperature. The first vapor flows from a first end of the closed ended tube to a second end of the closed ended tube where the first vapor dissipates heat through the tube. The first vapor condenses into the first liquid, in response to the first vapor dissipating heat through the tube. The second liquid is desorbed from the sorbent material, in response to the second liquid and the sorbent material reaching a predetermined desorption temperature that is less than the second boiling temperature. The second liquid vaporizes into a second vapor, in response to the second liquid reaching the second boiling temperature. 
     In one aspect, at least a portion of the second liquid is desorbed from the sorbent material and disposed in the bore prior to all of the first liquid vaporizing into the first vapor. 
     In another aspect, the first liquid is drawn by capillary action from the second end to the first end and through at least one axial groove formed in the inner diameter surface. 
     In another aspect, the thermocouple generates a first temperature signal associated with a temperature of the first liquid. The controller compares the temperature of the first liquid to a first temperature threshold, in response to the controller receiving the first temperature signal from the thermocouple. The controller generates a first warning notification signal, in response to the controller determining that the temperature of the first liquid is above the first temperature threshold. A display device displays a first warning indicative of the first liquid approaching the first temperature threshold, in response to the display device receiving the first warning notification signal from the controller. The thermocouple generates a second temperature signal associated with a temperature of the second liquid. The controller compares the temperature of the second liquid to a second temperature threshold, in response to the controller receiving the second temperature signal from the thermocouple. The controller generates a second warning notification signal, in response to the controller determining that the temperature of the second liquid is above the second temperature threshold. The display device displays a second warning indicative of the temperature of the second liquid approaching the second temperature threshold, in response to the display device receiving the second warning notification signal from the controller. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of one example of an electronics cooling system having an electronic component and a heat pipe for cooling the electronic component. 
         FIG. 2  is a cross-sectional view of one example of the heat pipe of  FIG. 1 , as taken along line  2 - 2 . 
         FIG. 3  is a cross-sectional view of the heat pipe of  FIG. 2 , as taken along line  3 - 3 , illustrating the heat pipe having an inner diameter surface defining a plurality of axial grooves for drawing condensed first liquid from a second end of the heat pipe to a first end of the heat pipe. 
         FIG. 4  is a chart illustrating multiple liquids in the heat pipe of  FIG. 1  cooling the electronic component of the printed circuit board. 
         FIG. 5  is a cross-sectional view of another example of the heat pipe of  FIG. 1 , illustrating the heat pipe including wick material with the inner diameter surface being free of axial grooves. 
         FIG. 6  is a cross-sectional view of the heat pipe of  FIG. 5 , as taken along line  6 - 6 , illustrating the sorbent material coated onto the inner diameter surface. 
         FIG. 7  is a cross-sectional view of the heat pipe of  FIG. 5 , as taken along line  7 - 7 , illustrating the wick material coated onto the inner diameter surface. 
         FIG. 8  is a cross-sectional view of yet another example of the heat pipe of  FIG. 1 . 
         FIG. 9  is a cross-sectional view of the heat pipe of  FIG. 8 , as taken along line  9 - 9 , illustrating the wick material coated having multiple protrusions extending from an integral layer of the wick material into associated recesses of the sorbent material. 
         FIG. 10  is a cross-sectional view of the heat pipe of  FIG. 8 , as taken along line  10 - 10 , illustrating the integral layer of the wick material. 
         FIG. 11  is a cross-sectional view of still another example of the heat pipe of  FIG. 1 , illustrating a layer of sorbent material having a thickness that is less than a thickness of a layer of the wick material. 
         FIG. 12  is a flow chart of one example of a method of operating the printed circuit board of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
     An exemplary electronics cooling system includes a heat pipe having a sorbent material to separate and recombine two or more liquids for cooling one or more electronic components. As described in the detailed examples below, the heat pipe includes two liquids having two different boiling temperatures with one liquid stored in a bore of a heat pipe and another liquid stored in a sorbent material. These two liquids provide a dual active thermal region (or a range of working temperatures) within which the heat pipe removes heat from the electronic component. The range of working temperatures can be extend from the lowest freezing point of the two liquids to the highest boiling point of the two liquids. Within this range, the liquids receive heat from the electronic component, which in turn increases the temperature of the liquids. One skilled in the art will understand that heat can be transferred by removing the heat from a heat source and flowing the heat to another substance, such as a liquid with or without causing the liquid to reach its boiling temperature. As but one example, the working temperature of a heat pipe with only water is from 32 degrees Fahrenheit (the freezing point) to 212 degrees Fahrenheit (the boiling point at sea level). Evaporation is vaporization on the water/air surface, and evaporation can happen at any temperature between the freezing point and the boiling point under 1 atmosphere of pressure while keeping the heat pipe functional. It is contemplated that the heat pipe can include more than two working liquids, and the sorbent material can be disposed in any position relative to the electronic components to tune the heat pipe for selecting the percentage of each liquid being used for cooling. Furthermore, the example of the system described in detail below is an open loop passive system with a gravity-fed closed-ended tube having a first closed end adjacent to the electronic component and a second closed end adjacent to a cooling fan. However, it is contemplated that other examples of the system can be a closed loop active system including a tube forming a loop and a pump pumping condensate through the loop to return to the electronic component. In addition, the examples of sorbent material described below are proximal to electronic components, it is contemplated that the sorbent material can be axially spaced from the electronic components and form a layer having any suitable thickness for providing an associated cooling characteristic. In still other examples, different sections of the sorbent material can initially store different liquids having associated boiling temperatures that are different from one another and are desorbed from the associated section of sorbent material at associated temperatures to remove heat from the electronic components. 
     Referring to  FIGS. 1 and 2 , one example of an electronics cooling system  100  includes an electronic component  104  that generates heat, in response to an electric current flowing through the electronic component  104 . The electronic component can be a processor, driver circuits, power circuits, memory, or any other electronic component that generates in response to receiving an electric current. 
     As best shown in  FIGS. 2 and 3 , the system  100  further includes a heat pipe  106  for cooling the electronic component  104 . The heat pipe  106  includes a tube  108  having an inner diameter surface  110  defining a bore  112 , with the tube  108  having first and second ends  114 ,  116  ( FIG. 2 ) along the bore  112 . The inner diameter surface  110  defines one or more axial grooves  118  extending between the first and second ends  114 ,  116  for drawing a first liquid  120  by capillary action from the second end  116  to the first end  114  as described in detail below. As best shown in  FIG. 3 , the axial grooves  118  are spaced circumferentially by a uniform distance from one another about the inner diameter surface  110 . It is contemplated that the grooves can be spaced circumferentially from one another by a variety of uniform or non-uniform distances about the inner diameter surface. 
     The heat pipe  106  further includes a sorbent material  122  coated onto the inner diameter surface  110  of the tube  108  and spaced from the first and second ends  114 ,  116  of the tube  108 . Put another way, the sorbent material  122  is coated onto an entire length of the inner diameter surface  110  except for a portion immediately adjacent to the first end  114  and another portion immediately adjacent to the second end  116 . The sorbent material  122  is configured to desorb at least a portion of a second liquid  124  into the bore  112  before all of the first liquid  120  vaporizes into a first vapor  126 . It is contemplated that the sorbent material can be coated onto any portion of the inner diameter surface. The sorbent material is selected from the group consisting of a zeolite, a silica gel, and a metal organic framework. However, in other examples, the sorbent material can include other suitable materials for desorbing and adsorbing the second liquid. 
     The first liquid  120  is contained within the bore  112  of the tube  108  and has a first boiling temperature. The first liquid  120  vaporizes into a first vapor  126 , in response to the tube  108  and the first liquid  120  receiving heat from the electronic component  104  and the first liquid  120  reaching the first boiling temperature. The first vapor  126  moves from the first end  114  to the second end  116  where the first vapor  126  dissipates heat through the tube  108  and condenses into the first liquid  120 . 
     The heat pipe  106  further includes a second liquid  124  that is adsorbed by the sorbent material  122  and has a second boiling temperature that is higher than the first boiling temperature of the first liquid  120 . The second liquid  124  is desorbed from the sorbent material  122  and vaporizes into a second vapor  128 , in response to the second liquid  124  reaching the second boiling temperature. In this example, the first liquid  120  is water with a boiling temperature of 212 degrees Fahrenheit, and the second liquid  124  is ethylene glycol with a boiling temperature of 387 degrees Fahrenheit. However, it is contemplated that the first and second liquids can be other suitable liquids with associated boiling temperatures. As shown in  FIG. 4 , during a first stage  130  of cooling, the first liquid  120  receives heat, which causes the temperature of the first liquid  120  to increase to the first boiling temperature BT 1  and vaporize. During a second stage  132  of cooling, the sorbent material  122  and the second liquid  124  receives heat from the electronic component  104  until the temperature of the sorbent material  122  and the second liquid  124  increases to a predetermined desorption temperature. The predetermined desorption temperature is lower than the second boiling temperature of the second liquid  124 . More specifically, in this example, the predetermined desorption temperature is lower than both the first boiling temperature of the first liquid  120  and the second boiling temperature of the second liquid  124 . Accordingly, before all of the first liquid  120  vaporizes, the second liquid  124  is released from the sorbent material  122 , in response to the temperature of the sorbent material  122  and the second liquid  124  reaching the predetermined desorption temperature. The second liquid  124  vaporizes, in response to the temperature of the second liquid  124  reaching the second boiling temperature BT 2 . 
     In one example, the sorbent material  122  can release the second liquid  124  to combine with the first liquid  120 , such that the boiling temperature of the resultant mixture can have a boiling temperature depending on the concentration of the mixture. Examples of the boiling temperature and concentration of ethylene glycol in water can include the values in the table below. 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                 Weight % 
                 Boiling Point 
                 Boiling Point 
               
               
                   
                 Ethylene 
                 of Solution 
                 of Solution 
               
               
                   
                 Glycol 
                 (deg F) 
                 (deg C) 
               
               
                   
                   
               
             
            
               
                   
                   0 
                 212 
                 100 
               
               
                   
                  10 
                 215 
                 102 
               
               
                   
                  20 
                 215 
                 102 
               
               
                   
                  30 
                 220 
                 104 
               
               
                   
                  40 
                 220 
                 104 
               
               
                   
                  50 
                 225 
                 107 
               
               
                   
                  60 
                 230 
                 110 
               
               
                   
                  70 
                 240 
                 116 
               
               
                   
                  80 
                 255 
                 124 
               
               
                   
                  90 
                 285 
                 140 
               
               
                   
                 100 
                 387 
                 197 
               
               
                   
                   
               
            
           
         
       
     
     The concentration or weight percentage of the solution can be controlled by at least one of: using predetermined liquids with associated boiling points, positioning sorbent materials holding those liquids at predetermined positions relative to the electronic components, and forming the sorbent material into layers of predetermined thicknesses. 
     Referring back to  FIG. 2 , the system  100  further includes one or more thermocouples  134  attached to at least one of the electronic component  104  and the heat pipe  106 , with the thermocouple  134  generating a first temperature signal associated with a temperature of the first liquid and a second temperature signal associated with the temperature of the second liquid  124 . More specifically, in this example, the at least one thermocouple  134  includes a first thermocouple  136  that is attached to the electronic component  104  and generates the first temperature signal. The at least one thermocouple  134  further includes a second thermocouple  138  that is attached to the heat pipe  106  and generates the second temperature signal. In other examples, the system includes a single thermocouple disposed within the bore of the tube or disposed in any other location and attached to any portion of the heat pipe or the electronic component. 
     The system  100  further includes a controller  140  electrically connected to the thermocouples  134 . The controller  140  compares the temperature of the first liquid  120  to a first temperature threshold, in response to the controller  140  receiving the first temperature signal from the thermocouple  134 . The controller  140  generates a first warning notification signal, in response to the controller  140  determining that the temperature of the first liquid  120  is above the first temperature threshold. In this example, the first temperature threshold is the first boiling temperature of the first liquid, such as 212 degrees Fahrenheit associated with water. The controller  148  compares the temperature of the second liquid  124  to a second temperature threshold, in response to the controller  140  receiving the second temperature signal from the thermocouple  134 . The controller  140  generates a second warning notification signal, in response to the controller  140  determining that the temperature of the second liquid  124  is above the second temperature threshold. Continuing with the previous example, the second temperature threshold is the second boiling temperature of the second liquid  124 , such as 387 degrees Fahrenheit associated with ethylene glycol. 
     The controller  140  is further electrically coupled to a display device  142  for displaying a first warning indicative of the first liquid  120  approaching the first temperature threshold, in response to the display device  142  receiving the first warning notification signal from the controller  140 . The display device  142  further displays a second warning indicative of the temperature of the second liquid  124  approaching the second temperature threshold, in response to the display device  142  receiving the second warning notification signal from the controller  140 . 
     The system  100  further includes a fan  144  that generates a flow of air over the second end  116  of the tube  108  and the fins  117  ( FIG. 2 ) extending from the tube  108  to dissipate heat from the same. 
     Referring to  FIGS. 5-7 , another example of a heat pipe  206  is similar to the heat pipe  106  of  FIG. 2  and includes the same components identified by the same reference numbers increased by  100 . While the heat pipe  106  of  FIGS. 2-3  has the axial grooves  118  for returning the first liquid  120  from the second end  116  to the first end  114 . The heat pipe  206  includes an inner diameter surface  210  free of grooves. The heat pipe  206  includes a wick material  250  that is coated onto the inner diameter surface  210  and is different from the sorbent material  222 . The wick material  250  extends from a portion of the inner diameter surface  210  adjacent to the second end  216  to a portion of the inner diameter surface  210  adjacent to the electronic component  204 . The wick material  250  absorbs the first liquid  220  after the first vapor  226  travels from the first end  214  to the second end  216  where the first vapor  226  dissipates heat through the tube  208  and condenses into the first liquid  220 , such that the wick material  250  draws the first liquid  220  from the second end  216  toward the first end  214 . While the heat pipe  106  of  FIG. 2  includes a tube  108  with sorbent material  122  extending from a portion proximal to the first end  114  to another portion proximal to the second end  116 , the heat pipe  206  includes a sorbent material  222  coated onto only a portion immediately adjacent to the first end  214 . The entire sorbent material  222  and a portion of the electronic component  204  are disposed co-extensive relative to one another along the tube  208 , with another portion of the electronic component  204  extending axially beyond the sorbent material  222 . 
     Referring to  FIGS. 8-10 , another example of a heat pipe  306  is similar to the heat pipe  206  of  FIGS. 5-7  and includes the same components identified by the same reference numbers increased by  100 . While the entire sorbent material  222  and only a portion of the electronic component  204  of  FIGS. 4-6  are disposed co-extensive relative to one another along the tube  208 , the entire electronic component  304  and a portion of the sorbent material  322  are disposed co-extensive relative to one another along the tube  308 , with another portion of the sorbent material  322  extending axially beyond the electronic component  304 . As compared to the heat pipe  206  of  FIGS. 5-7 , the heat pipe  306  includes an arrangement of the sorbent material  322  relative to the electronic component  304  that can transfer heat to more of the second liquid  324  at a faster rate than the heat pipe  206  of  FIGS. 5-7 . Furthermore, the sorbent material  322  includes a plurality of recesses  352 , and the wick material  350  includes a layer  354  extending from the sorbent material  322  to the second end  316  with a plurality of protrusions  358  extending from the layer  354  into the recesses  352  of the sorbent material  322 , such that the first liquid  320  can be drawn from the second end  316  to the first end  314  of the tube  308 . 
     Referring to  FIG. 11 , another example of a heat pipe  406  is similar to the heat pipe  306  of  FIGS. 8-10  and includes the same components identified by the same reference numbers increased by  100 . However, while the entire electronic component  304  and only a portion of the sorbent material  322  of  FIGS. 8-10  are coextensive with one another, the entire electronic component  404  and the entire sorbent material  422  are coextensive with one another. Furthermore, while the sorbent material  322  and wick material  350  of  FIGS. 8-10  form respective layers having thicknesses that are equal with one another, the sorbent material  422  forms a layer  458  having a thickness that is less than the thickness of the layer  454  of wick material  450 . 
     Referring to  FIG. 12 , a method  500  of operating the system  100  of  FIG. 2  is provided. The method  500  begins at block  502  with the electronic component  104  transferring heat through the tube  108  to the first liquid  120 . The electronic component or other portion of the system can generate heat when the electrical component receives an electric current. 
     At block  504 , the first liquid  120  vaporizes into the first vapor  126 , in response to the first liquid  120  receiving heat from the electronic component  104  and the first liquid  120  reaching the first boiling temperature. 
     At block  506 , the first thermocouple  136  generates a first temperature signal associated with a temperature of the first liquid. 
     At block  508 , the controller  140  compares the temperature of the first liquid  120  to a first temperature threshold, in response to the controller receiving the first temperature signal from the first thermocouple  136 . In this example, the first temperature threshold is the first boiling temperature. However, it is contemplated that the first temperature threshold can be above or below the first boiling temperature. For instance, to provide additional warning of the first liquid  120  drying out, the first temperature threshold can be a temperature that is less than the first boiling temperature of the first liquid  120 . If the temperature of the first liquid  120  is below the first temperature threshold, the method repeats block  508 . If the temperature of the first liquid  120  is above the first temperature threshold, the method proceeds to block  510 . 
     At block  510 , the controller  140  generates a first warning notification signal, in response to the controller  140  determining that the temperature of the first liquid  120  is above the first temperature threshold. 
     At block  512 , a display device  142  displays a first warning indicative of the first liquid  120  approaching the first temperature threshold, in response to the display device receiving the first warning notification signal from the controller  140 . 
     At block  514 , the first vapor  126  flows toward the second end  116  and the fins  117  where the first vapor  126  dissipates heat through the tube  108  and the fins  117 . 
     At block  516 , the first vapor  126  condenses into the first liquid  120 , in response to the first vapor  126  dissipating heat through the second end  116  of the tube  108 . 
     At block  518 , the first liquid  120  is drawn by capillary action from the second end  116  to the first end  114  through the axial grooves  118  formed in the inner diameter surface  110 . 
     At block  520 , the second liquid  124  is desorbed from the sorbent material  122  and vaporizes into the second vapor  128 , in response to the second liquid  124  reaching the second boiling temperature. In this example, at least a portion of the second liquid  124  is desorbed from the sorbent material  122  into the bore  112  before all of the first liquid  120  vaporizes into the first vapor  126 . This can be accomplished by providing liquids of predetermined boiling points, sorbent materials disposed in multiple arrangements relative to the electronic components, and layers of sorbent material having any suitable thickness. 
     At block  522 , the second thermocouple  138  generates a second temperature signal associated with a temperature of the second liquid  124 . 
     At block  524 , the controller  140  compares the temperature of the second liquid  124  to a second temperature threshold, in response to the controller  140  receiving the second temperature signal from the second thermocouple  138 . In this example, the second temperature threshold is the second boiling temperature. However, it is contemplated that the second temperature threshold can be above or below the second boiling temperature. For instance, to provide additional warning of the second liquid  124  drying out, the second temperature threshold can be less than the second boiling temperature of the second liquid  124 . If the temperature of the second liquid  124  is below the second temperature threshold, the method repeats block  524 . If the temperature of the second liquid  124  is above the second temperature threshold, the method proceeds to block  526 . 
     At block  526 , the controller  140  generates a second warning notification signal, in response to the controller  140  determining that the temperature of the second liquid  124  is above the second temperature threshold. 
     At block  528 , the display device  142  displays a second warning indicative of the temperature of the second liquid approaching the second temperature threshold, in response to the display device receiving the second warning notification signal from the controller  140 . In this example, the second temperature threshold is the second boiling temperature. However, it is contemplated that the second temperature threshold can be above or below the second boiling temperature. For instance, to provide additional warning of the second liquid  124  drying out, the second temperature threshold can be a temperature that is less than the second boiling temperature. 
     The description of the present disclosure is merely exemplary in nature and variations that do not depart from the general sense of the present disclosure are intended to be within the scope of the present disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the present disclosure.