Patent Publication Number: US-2023161391-A1

Title: Modular Liquid Cooling Architecture For Liquid Cooling

Description:
BACKGROUND 
     Computer hardware, such as dual in-line memory modules (“DIMMs”) and central processing units (“CPUs”), generates heat during operation, and tends to operate better and fail at lower rates when cooled. For this reason, liquid cooling systems have been developed to cool computer hardware. Some motherboards, server assemblies, and other apparatus in which heat-generating computer hardware can operate are modular in design. That is, some devices may be configured to allow the addition and removal of a variable quantity of DIMMs, CPUs, or other heat generating hardware. Moreover, hardware of a given type, such as individual DIMMs, may have variable cooling needs depending on the model and use case. Cooling systems for these devices are therefore typically designed for the maximum-use case of a specific apparatus in which computer hardware may be installed so that, when a maximum amount of computer hardware is installed and running, all of the hardware will be cooled adequately. As a result, when less than the maximum amount of hardware is installed and in operation, more coolant than necessary may flow through the cooling system. Cooling efficiency may be improved by systems that could be dynamically adapted to various arrangements of computer hardware. 
     BRIEF SUMMARY 
     Aspects of this disclosure are directed to a liquid cooling system that can independently adjust or shut off flow at certain points in the system. In this regard, the cooling system may include multiple conduits or cold plates connected in parallel flow between a first manifold and a second manifold. The first manifold may be, for example, an inlet manifold and the second manifold may be an outlet manifold. Either or both of the inlet manifold and the outlet manifold may include one or more valves located between points where different conduits connect to the manifold. The one or more valves may be operable to adjust or shut off liquid flow across certain points in the manifold. The one or more valves may therefore be operable to change a flow pattern or sequence through the cooling system. For example, the valves may be operable to change the fluid connection among the conduits between parallel and series flow. The valves may be able to place some conduits in series flow and other conduits in parallel flow. The valves may further be operable to change an order of the series connection between the conduits and, as a result, the relative temperature of the cooling fluid as it passes certain components. The cooling system overall may therefore be operable to prioritize cooling of components that require more cooling by directing the cooling liquid to flow past those components before it flows past components that need less cooling. Likewise, the cooling system may be operable to direct the liquid such that components with lower cooling needs, or empty sockets in which no component is installed, are passed by the liquid last. The cooling system may therefore be configurable to adjust an amount of cooling fluid used to suit a given arrangement of computer hardware. 
     In some arrangements, cooling systems may include an inlet and an outlet manifold positioned on opposite ends of one or more groups of parallel DIMM slots. Liquid conduits may extend in cold plates positioned adjacent the DIMM slots to fluidly connect the manifolds. Each DIMM slot may be positioned between two cold plates such that a DIMM in any slot will be in contact with two cold plates. Both the inlet manifold and the outlet manifold may have valves between some of the respective points of connection with the conduits in a single group of conduits. When all of the valves in the inlet manifold and the outlet manifold positioned between the conduits that flow across a single group of DIMM slots are open, the cooling liquid may flow in parallel from the inlet manifold, through the cold plates associated with the group of conduits, and into the outlet manifold. The valves in the inlet manifold may be staggered relative to the valves in the outlet manifold such that, when all of the valves in both manifolds positioned between the conduits that flow across a single group of DIMM slots are closed, the cooling liquid will flow through the conduits in series in a serpentine pattern that travels from the inlet manifold to the outlet manifold and back again at least once. For example, in a group of five conduits spaced to run alongside four DIMMs, with the first through fifth conduits in the group being connected to each manifold in numerical order, one of the manifolds may include a valve between points of connection for the first and second conduit and another valve between points of connection for the third and fourth conduit while the other manifold includes a valve between points of connection for the second and third conduit and another valve between points of connection for the fourth and fifth conduit. 
     In another aspect, a heat exchanger may comprise a first manifold having an inlet opening, a second manifold having an outlet opening, and a group of conduits fluidly connecting the first manifold and the second manifold to one another such that a flow path is established for liquid to flow from the inlet opening to the outlet opening. The flow path may include a select portion that extends through all conduits within the group of conduits. The heat exchanger may also comprise valves located in the first manifold and the second manifold. The valves may be operable to change the select portion of the flow path between a first state, wherein the conduits within group of conduits are fluidly connected in parallel with one another, and a second state, wherein the conduits within the group of conduits are fluidly connected in series with one another. 
     In some arrangements according to any of the foregoing, the group of conduits may be a first group of conduits and the select portion may be a first select portion. The heat exchanger may also comprise a second group of conduits fluidly connecting the first manifold and the second manifold to one another such that a second select portion of the flow path between the inlet opening. The outlet opening may extend through all conduits within the second group of conduits. The valves may be operable to change the first select portion of the flow path between the first state and the second state without changing the second select portion of the flow path. 
     In some arrangements according to any of the foregoing, the valves may be operable to change the second select portion of the flow path between a first state, wherein the conduits within the second group of conduits are connected in parallel with one another, and a second state, wherein the conduits within the second group of conduits are connected in series with one another, without changing the first select portion of the flow path. 
     In some arrangements according to any of the foregoing, the heat exchanger may comprise an independent conduit fluidly connecting the first manifold and the second manifold in parallel with the first group of conduits and the second group of conduits. 
     In some arrangements according to any of the foregoing, the first select portion and second select portion may be in parallel with one another when the first select portion is in the first state. The second select portion may follow the first select portion in series when the first select portion is in the second state. 
     In some arrangements according to any of the foregoing, every conduit within the first group of conduits may be fluidly connected to a portion of the first manifold nearer to the inlet opening than a portion of the first inlet manifold to which every conduit in the second group of conduits is connected. 
     In some arrangements according to any of the foregoing, the first select portion and the second select portion may be in parallel with one another when the first select portion is in the first state and when the first select portion is in the second state. 
     In some arrangements according to any of the foregoing, every conduit within the first group of conduits may be fluidly connected to a portion of the first manifold on an opposite side of the inlet opening from a portion of the first inlet manifold to which every conduit in the second group of conduits is connected. 
     In some arrangements according to any of the foregoing, the inlet opening may be a first inlet opening. The heat exchanger may also comprise a third manifold having a second inlet opening. The heat exchanger may also comprise a third group of conduits fluidly connecting the third manifold to the second manifold. 
     In some arrangements according to any of the foregoing, the outlet opening may be a first outlet opening. The heat exchanger may also comprise a third manifold having a second outlet opening. The heat exchanger may also comprise a third group of conduits fluidly connecting the first manifold to the third manifold. 
     In some arrangements according to any of the foregoing, the group of conduits may comprise a first conduit fluidly connected to the first manifold at a first point and fluidly connected to the second inlet manifold at a second point, a second conduit fluidly connected to the first manifold at a third point and fluidly connected to the second inlet manifold at a fourth point, and a third conduit fluidly connected to the first manifold at a fifth point and fluidly connected to the second inlet manifold at a sixth point, the third point being between the first and fifth points and the fourth point being between the second and sixth point. The valves comprise a first valve operable to open and close fluid connection between the first and third points, and a second valve operable to open and close fluid connection between the fourth and sixth points. In some arrangements according to any of the foregoing, the group of conduits may further comprise a fourth conduit fluidly connected to the first manifold at a seventh point and fluidly connected to the second manifold at an eighth point. The seventh point may be on an opposite side of the fifth point from the third point and the eighth point may be on an opposite side of the sixth point from the fourth point. The valves may further comprise a third valve operable to open and close fluid connection between the fifth and seventh points. In some arrangements according to any of the foregoing, the group of conduits may further comprise a fifth conduit fluidly connected to the first manifold at a ninth point and fluidly connected to the second manifold at a tenth point. The ninth point may be on an opposite side of the seventh point from the fifth point and the tenth point may be on an opposite side of the eight point from the sixth point. The valves may further comprise a fourth valve operable to open and close fluid connection between the eighth and tenth points. 
     In some arrangements according to any of the foregoing, the valves may be operable to change the select portion of the flow path to a third state wherein at least one conduit within the group of conduits is fluidly connected in parallel with at least one other conduit within the group of conduits and at least one conduit within the group of conduits is fluidly connected in series with at least one other conduit within the group of conduits. 
     In another aspect, a liquid cooling system for a computer hardware arrangement may comprise a first manifold having an inlet opening, a second manifold having an outlet opening, and a group of cold plates extending between the first and second manifolds. Each of the cold plates within the group of cold plates may have a conduit extending therethrough and fluidly connecting the first manifold to the second manifold to define a portion of a flow path between the inlet and outlet openings. The system may be convertible between a first state wherein the conduits in the cold plates are fluidly connected in parallel and a second state wherein the conduits in the cold plates are fluidly connected in series. 
     In some arrangements according to any of the foregoing, the cold plates within the group of cold plates may be evenly spaced from one another. 
     In some arrangements according to any of the foregoing, the group of cold plates may be a first group of cold plates and comprising a second group of cold plates. The cold plates within the second group of cold plates may be evenly spaced from one another. Each of the cold plates within the second group of cold plates may have a conduit extending therethrough and fluidly connecting the first manifold to the second manifold to define a portion of the flow path. The system may be convertible between a third state wherein the conduits in the cold plates are fluidly connected in parallel and a fourth state wherein the conduits in the cold plates are fluidly connected in series. Each of the first state and the second state may be independent from and capable of coexisting with both the third state and the fourth state. 
     In some arrangements according to any of the foregoing, the system may comprise an independent cold plate having a conduit extending therethrough and fluidly connecting the first manifold and the second manifold to define a portion of the flow path. The independent cold plate may be equally spaced from the first group and the second group by a distance greater than a distance between adjacent cold plates in the first group and a distance between adjacent cold plates in the second group. 
     In some arrangements according to any of the foregoing, the system may comprise either or both of an independent cold plate fluidly connected upstream of the inlet opening relative to the flow path and an independent cold plate fluidly connected downstream of the outlet opening relative to the flow path. 
     In another aspect, a method of adjusting a cooling capacity of a computer hardware cooling system may include actuating valves in the system to change a fluid connection among cold plates extending between DIMM slots between parallel and series flow. 
     In some, though not all, implementations of the foregoing method, the fluid connection among the cold plates may be provided by conduits extending along the cold plates and between two manifolds, and the valves may be located within the manifolds. Each of the valves may be located at a point within its respective manifold between two fluid connection points, wherein each of the fluid connection points is a location where the manifold is fluidly connected to a respective one of the conduits. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic illustration of a computer hardware cooling system in a first state. 
         FIG.  2    is a schematic illustration of the computer hardware cooling system of  FIG.  1    in a second state. 
         FIG.  3    is a schematic illustration of a computer hardware cooling system in a multiple load type arrangement. 
         FIG.  4    is a schematic illustration of a computer hardware cooling system in a double inlet manifold arrangement. 
         FIG.  5    is a schematic illustration of a computer hardware cooling system in a double outlet manifold arrangement. 
         FIG.  6    is a schematic illustration of a computer hardware cooling system in a multi-inlet manifold and multi-outlet manifold arrangement. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    illustrates a cooling system  100  for cooling a computer hardware arrangement  150 . Cooling system  100  is a heat exchanger that includes a cold or inlet manifold  110 , a hot or outlet manifold  120 , and cold plates  144   a ,  144   b ,  144   c ,  144   d ,  144   e . First cold plate  144   a , second cold plate  144   b , third cold plate  144   c , fourth cold plate  144   d , and fifth cold plate  144   e  are arranged in order from first through fifth and left to right from the perspective of  FIG.  1    and may be referred to collectively as cold plates  144  that together constitute a cold plate group  140 . The illustrated example of system  100  includes five cold plates  144 , but various arrangements of system  100  can include any plural number of cold plates  144 . 
     Each cold plate  144  has a respective point of connection to both inlet manifold  110  and outlet manifold  120 . Thus, first cold plate  144   a  connects to inlet manifold  110  at a first inlet manifold connection point  141   a  and connects to outlet manifold  120  at a first outlet manifold connection point  142   a , second cold plate  144   b  connects to inlet manifold  110  at a first inlet manifold connection point  141   b  and connects to outlet manifold  120  at a second outlet manifold connection point  142   b , third cold plate  144   c  connects to inlet manifold  110  at a third inlet manifold connection point  141   c  and connects to outlet manifold  120  at a third outlet manifold connection point  142   c , fourth cold plate  141   d  connects to inlet manifold  110  at a fourth inlet manifold connection point  141   d  and connects to outlet manifold  120  at a fourth outlet manifold connection point  142   d , and fifth cold plate  144   e  connects to inlet manifold  110  at a fifth inlet manifold connection point  141   e  and connects to outlet manifold  120  at a fifth outlet manifold connection point  142   e.    
     Each cold plate  144  includes a contact element, such as a plate of thermally conductive material, and a conduit extending through the contact element and fluidly connecting inlet manifold  110  to outlet manifold  120 . Cooling of any object with any cold plate  144  may be therefore achieved by placing the contact element of any cold plate  144  in contact with a with the object and running liquid below the target temperature for the object through the cold plate&#39;s  144  conduit. The contact element will conduct heat from the object to the fluid in the conduit, and the heated fluid will be carried away by the continuing flow of fluid. Suitable thermally conductive materials include, for example, certain ceramics, polymers, metals, etc., with some specific examples of suitable metals being copper or aluminum. Cold plate  144  may optionally be constructed of one of the foregoing materials or any combination of the foregoing materials. For example, the contact element may be monolithically formed, and the conduit may simply be a space provided within the contact element. In another example, a tube, which may be round, fattened, or in any other shape of a first material may define the conduit, and a spreader of a second material and surrounding the tube may define an outer surface of the contact element. In some examples, the tube may be a flattened copper tube, and the spreader may be constructed of aluminum. 
     Inlet manifold  110  includes an inlet opening  111  that receives relatively cool supply fluid  131  from a fluid source  130 . Similarly, outlet manifold  120  includes an outlet opening  122  from which return fluid  132  carrying heat received from the cooled hardware returns to the fluid source  130 . Inlet opening  111  is on an opposite side of first inlet manifold connection point  141   a  from second inlet manifold connection point  141   b , third inlet manifold connection point  141   c , fourth inlet manifold connection point  141   d , and fifth inlet manifold connection point  141   e . Outlet opening  122  is on an opposite side of fifth outlet manifold connection point  142   e  from fourth outlet manifold connection point  142   d , third outlet manifold connection point  142   c , second outlet manifold connection point  142   b , and first outlet manifold connection point  142   a . A flow path from inlet opening  111  to outlet opening  122  carries the fluid through inlet manifold  110 , cold plates  144 , and outlet manifold  120  as indicated by the lines extending through inlet manifold  110 , cold plates  144 , and outlet manifold  120  and in the direction shown by the arrows drawn on cold plates  144 . Fluid source  130  may be any system that can provide fluid at a suitable temperature and cool or dispose of fluid returned at an unsuitable temperature. For example, fluid source  130  may be a coolant supply system of a building in which cooling system  100  is installed, such as the coolant supply systems commonly found in commercial data centers. The cooling fluid can be liquid, such as, for example, water, glycol and water solutions, or dielectric fluids such as fluorocarbons, or certain other liquids, or gas such as, for example, air, carbon dioxide, or certain other gases. 
     In the illustrated example, cold plates  144  extend along dual in-line memory modules (“DIMMs”)  155   a ,  155   b ,  155   c ,  155   d . First DIMM  155   a , second DIMM  155   b , third DIMM  155   c , and fourth DIMM  155   d  are arranged in order from first through fourth and from left to right from the perspective of  FIG.  1    and may be referred to collectively as DIMMs  155  that together constitute a DIMM group  150 . Each DIMM  155  is located between and in contact with two adjacent cold plates  144 . DIMMs  155  may contact cold plates  144  directly or through a thermal interface material pad. In DIMMs  155  of typical construction, and in the illustrated example, each DIMM  155  includes a printed circuit board (“PCB”) running along a length thereof and multiple dynamic random-access memory (“DRAM”) chips on either side of the PCB. In the illustrated example, the DRAM chips contact cold plates  144  while the PCB is spaced from cold plates  144 . Each pair of adjacent cold plates  144  within cold plate group  140  may be equally spaced from each other such that equally sized DIMMs  155  may each be contacted by a cold plate  144  on both sides. Thus, in the illustrated example, system  100  is installed to extend over four parallel DIMM slots, with each DIMM slot being located between a pair of adjacent cold plates  144 . However, DIMMs  144  are shown and described by way of example only, and system  100  and any other systems in this disclosure may be adapted for cooling other hardware. Thus, for any reference to an interaction between any particular cooling system and DIMMs throughout this description, it should be understood that the cooling system could interact with other hardware in a similar manner Moreover, though four DIMMs  144  are shown in the illustrated example, system  100  may be adapted for any number of DIMMs or hardware elements to be cooled. 
     Inlet manifold  110  contains a first inlet manifold valve  116   a  and a second inlet manifold valve  116   b  numbered according to increasing distance along the flow path from inlet opening  111  and which may collectively be referred to as inlet manifold valves  116 . First inlet manifold valve  116   a  is located between first inlet manifold connection point  141   a  and second inlet manifold connection point  141   b . Thus, when first inlet manifold valve  116   a  is closed, fluid is prevented from flowing between first inlet manifold connection point  141   a  and second inlet manifold connection point  141   b  within inlet manifold  110 , and when first inlet manifold valve  116   a  is open, fluid may flow between first inlet manifold connection point  141   a  and second inlet manifold connection point  141   b  within inlet manifold  110 . First inlet manifold valve  116   a  is therefore operable to open and close fluid connection between first inlet manifold connection point  141   a  and second inlet manifold connection point  141   b  within inlet manifold  110 . Second inlet manifold valve  116   b  is similarly located within inlet manifold  110  between third inlet manifold connection point  141   c  and fourth inlet manifold connection point  141   d . Second inlet manifold valve  116   b  is therefore similarly operable to open and close fluid connection between third inlet manifold connection point  141   c  and fourth inlet manifold connection point  141   d.    
     Outlet manifold  120  similarly contains a first outlet manifold valve  126   a  and a second outlet manifold valve  126   b  numbered according to increasing distance along the flow path from inlet opening  111  and which may collectively be referred to as outlet manifold valves  126 . First outlet manifold valve  126   a  is located within outlet manifold  120  between second outlet manifold connection point  142   b  and third outlet manifold connection point  142   c , and second outlet manifold valve  126   b  is located within outlet manifold  120  between fourth outlet manifold connection point  142   d  and fifth outlet manifold connection point  142   e . First outlet manifold valve  126   a  is therefore operable to open and close fluid connection between second outlet manifold connection point  142   b  and third outlet manifold connection point  142   c  within outlet manifold  120 , and second outlet manifold valve  126   b  is operable to open and close fluid connection between fourth outlet manifold connection point  142   d  and fifth outlet manifold connection point  142   e  within outlet manifold  120 . 
     Valves  116 ,  126  may be any type of valve operable to selectively either permit fluid flow across a point or seal off and prevent fluid flow across the same point. Valves  116 ,  126  may therefore be manually or mechanically operated valves in some examples, and in other examples valves  116 ,  126  may be electrically operated and controlled valves. Valves  116 ,  126  in some arrangements may therefore be electronically controllable by a control circuit, programmable controller, or computer, etc. The mechanism of the valves may be in the style of, for example, ball valves, butterfly valves, check valves, gate valves, globe valves, needle valves, pinch valves, plug valves, or any other type of valve that can selectively permit or prevent flow across a point in a fluid flow path. 
     The above described positions of the valves  116 ,  126  means that inlet manifold valves  116  and outlet manifold valves  126  are staggered relative to each other. That is, inlet manifold valves  116  are offset within inlet manifold  110  relative to outlet manifold valves&#39;  126  positions within outlet manifold  120  such that the cold plates  144  that inlet manifold valves  116  stand between within inlet manifold  110  alternate with the cold plates  144  between which outlet manifold valves  126  stand within outlet manifold  120 . Inlet manifold valves  116  are therefore offset from outlet manifold valves  126  in at least two dimensions, one dimension being a location along the flow path within the respective manifolds  110 ,  120 , the other dimension being along the manifolds  144 . Both first outlet manifold valve  126   a  and second outlet manifold valve  126   b  are operable to open or close fluid connection within outlet manifold  120  between a respective pair of cold plates  144  that neither inlet manifold valve  116  can close the connection between within inlet manifold  110 . Similarly, both first inlet manifold valve  116   a  and second inlet manifold valve  116   b  are operable to open or close fluid connection within inlet manifold  110  between a respective pair of cold plates  144  that neither outlet manifold valve  126  can close the connection between within outlet manifold  120 . The staggered pattern of valves and connection points may be continued to accommodate any number or size of cold plates, wherein valves  116  within the manifold into which fluid is supplied, such as inlet manifold  110 , are located immediately following each odd numbered supply side connection point  141  and immediately preceding each even numbered supply side connection point  141 , and valves  126  in the opposite manifold, such as outlet manifold  110 , are located immediately following each even numbered non-supply side connection point  142  and immediately preceding each odd numbered non-supply side connection point  142 , except that no valve needs to precede the connection points for the first cold plate or follow the connection points for the last cold plate. 
       FIG.  1    illustrates the flow path of the cooling fluid when system  100  is in a first or parallel state in which all inlet manifold valves  116  and all outlet manifold valves  126  are open. As shown by the arrows on the flow lines within manifolds  144  in  FIG.  1   , the flow path of the cooling fluid extends through each cold plate  144  in parallel from inlet manifold  110  to outlet manifold  120 . Thus, each cold plate  144  receives the cooling fluid from inlet manifold  110  at an approximately equal temperature when system  100  is in the parallel state. First cold plate  144   a  and fifth cold plate  144   e  each contact only one DIMM  155 , meaning system has somewhat greater cooling capacity for first DIMM  155   a  and fourth DIMM  155   d  than for second DIMM  155   b  and third DIMM  155   c , but system  100  otherwise has approximately equal cooling capacity for each DIMM  155  in DIMM group  150  in the parallel state. 
       FIG.  2    illustrates the flow path of the cooling fluid when system  100  is in a second or series state in which all inlet manifold valves  116  and all outlet manifold valves  126  are closed. Because inlet manifold valves  116  are staggered from outlet manifold valves  126 , connection between any pair of adjacent cold plates  144  is closed only within one of the manifolds  110 ,  120 , while connection between the same pair of adjacent cold plates  144  remains open in the opposite manifold  110 ,  120 , and the manifold  110 ,  120  within which the connection remains open alternates among adjacent pairs. Thus, no cold plate  144  is shut off entirely in the series state of system  100 . 
     Because inlet opening  111  is on an opposite side of first inlet manifold connection point  141   a  from cold plate group  140  as a whole while outlet opening  122  is on an opposite side of fifth outlet manifold connection point  142   e  from cold plate group  140  as a whole, the cooling fluid must travel in a serpentine pattern from inlet manifold  110  to outlet manifold  120  and back again, through each cold plate  144  in cold plate group  140 , to reach outlet opening  122  when system  100  is in the series state. As shown by the arrows on the flow lines within manifolds  144  in  FIG.  2   , the flow path of the cooling fluid therefore extends through each cold plate  144  in series from inlet opening  111  to outlet opening  122 . Thus, assuming all DIMMs  155  exceed the temperature of return fluid  132 , each cold plate  144  other than first cold plate  144   a  receives the cooling fluid at a greater temperature than the temperature at which the cooling fluid was received by the preceding cold plate  144  when system  100  is in the series state. 
     The series state of system  100  as shown in  FIG.  2    prioritizes cooling to hardware nearer along the flow path to inlet opening  111 . First cold plate  144   a  receives the cooling fluid at the lowest temperature, second cold plate  144   b  receives the cooling fluid at a slightly higher temperature, and so on to fifth cold plate  144   e , when cold plates  144  are connected in series. System  100  therefore has the greatest cooling capacity at the location of first DIMM  155   a  and the least cooling capacity at the location of fourth DIMM  155   d  in the series state. For this reason, the series state may be more efficient than the parallel state for applications where hardware further along the flow path from inlet opening  111  needs less cooling than other hardware, or when one or more downstream DIMMs  155  are deactivated or removed. As such, the operability of valves  116 ,  126  to change system  100  between the parallel state and the series state enables system  100  to be dynamically adapted to various arrangements of hardware having different cooling needs. 
     Though not specifically illustrated, flow paths that are partially in parallel and partially in series can be achieved by operating like numbered pairs of one inlet manifold valve  116  and one outlet manifold valve  126  independently from one another. For example, if first inlet manifold valve  116   a  and first outlet manifold valve  126   a  are left open while second inlet manifold valve  116   b  and second outlet manifold valve  126   b  are closed, the cooling fluid will flow in parallel through first cold plate  144   a , second cold plate  144   b , and third cold plate  144   c , then in series through fourth cold plate  144   d  followed by fifth cold plate  144   e  Similarly, if first inlet manifold valve  116   a  and first outlet manifold valve  126   a  are closed while second inlet manifold valve  116   b  and second outlet manifold valve  126   b  are left open, the cooling fluid will flow in series through first cold plate  144   a  followed by second cold plate  144   b  before flowing in parallel through third cold plate  144   c , fourth cold plate  144   d , and fifth cold plate  144   e.    
       FIG.  3    shows a system  200  including an inlet manifold  210  and an outlet manifold  220  having multiple distinct cold plate groups  240  and independent cold plates  264  connected, when all valves  216 ,  226  are open, in parallel between inlet manifold  210  and outlet manifold  220 . System  200  also includes a first cold plate group  240   a , a second cold plate group  240   b , a third cold plate group  240   c , and a fourth cold plate group  240   d , which are numbered according to increasing distance along inlet manifold  210  from an inlet opening  211  of inlet manifold  210  and may be referred to collectively as cold plate groups  240 . In system  200 , elements are generally alike to like numbered elements of system  100  except for specifically stated or illustrated differences. As such, inlet manifold  210  receives supply fluid  231  from a fluid system  230  through inlet opening  211  and outlet manifold  220  releases return fluid  232  through an outlet opening  222  in a manner similar to the receipt of supply fluid  131  by inlet manifold  110  through inlet opening  111  and release of return fluid  132  from outlet manifold  120  through outlet opening  122 . Likewise, each cold plate group  240  includes multiple cold plates  244 , and each cold plate  244  includes a thermally conductive contact element and a conduit that extends through the contact element and provides fluid connection between inlet manifold  210  and outlet manifold  220 . The four cold plate groups  240  shown in  FIG.  3    are presented as an example, and systems  200  according to other arrangements and having any plural number of cold plate groups  240  connected to inlet manifold  210  on a common side of inlet opening  211  and connected in an opposite order to outlet manifold  220  on a common side of outlet opening  222  may operate in a similar manner 
     Inlet manifold  210  contains a first inlet manifold valve  216   a , a second inlet manifold valve  216   b , a third inlet manifold valve  216   c , a fourth inlet manifold valve  216   d , a fifth inlet manifold valve  216   e , a sixth inlet manifold valve  216   f , a seventh inlet manifold valve  216   g , and an eighth inlet manifold valve  216   h  numbered according to increasing distance along the flow path from inlet opening  211  and which may collectively be referred to as inlet manifold valves  216 . Outlet manifold  220  similarly contains a first outlet manifold valve  226   a , a second outlet manifold valve  226   b , a third outlet manifold valve  226   c , a fourth outlet manifold valve  226   d , a fifth outlet manifold valve  226   e , a sixth outlet manifold valve  226   f , a seventh outlet manifold valve  226   g , and an eighth outlet manifold valve  226   h  numbered according to increasing distance along the flow path from inlet opening  211  and which may collectively be referred to as outlet manifold valves  226 . Two inlet manifold valves  216  and two outlet manifold valves  226  are associated with each manifold group  240  in numerical sequence such that first inlet manifold valve  216   a , first outlet manifold valve  226   a , second inlet manifold valve  216   b , and second outlet manifold valve  226   b  are associated with first cold plate group  240   a , while third inlet manifold valve  216   c , third outlet manifold valve  226   c , fourth inlet manifold valve  216   d , and fourth outlet manifold valve  226   d  are associated with second cold plate group  240   b  and so on. 
     The inlet manifold valves  216  associated with any cold plate group  240  are staggered relative to the outlet manifold valves  226  associated with the same cold plate group  240  in the same manner as described above with regard to valves  116 ,  126  and cold plate group  140  of  FIGS.  1  and  2   . As such, valves  216 ,  226  are operable to change the portion of system&#39;s  200  flow path through each cold plate group  240  between parallel flow and series flow. Valves  216 ,  226  associated with any cold plate group  240  may optionally be operable independently from valves  216 ,  226  associated with other cold plate groups  240  such that parallel or series flow may be chosen individually for each cold plate group  240 . As noted above with regard to cold plate group  140 , the illustrated arrangement of four cold plates  244 , two inlet manifold valves  216 , and two outlet manifold valves  226  is merely an example, and cold plate groups  240  according to other arrangements may have other numbers of cold plates  244  and valves  216 ,  226 . A group of cold plates having any odd number of at least three cold plates and having a number of staggered, paired, associated valves equal to one less than the number of cold plates may function in the same way as described with regard to cold plate groups  140 ,  240 . 
     Because cold plate groups  240  are connected to manifolds  210 ,  220  sequentially, inlet opening  211  is on an opposite side of the connections of first cold plate group  240   a  to inlet manifold  210  from the connection points of all other cold plate groups  240 , and outlet opening  222  is on an opposite side of the connection point of fourth cold plate group  240   d , which is the last cold plate group  240 , from the connection points of all other cold plate groups  240  to outlet manifold  220 , the flow path from inlet opening  211  to outlet opening  222  must pass through each cold plate group  240 . When all valves  216 ,  226  are open, the flow path from inlet opening  211  to outlet opening  222  will flow through the cold plate groups  240  in parallel such that each cold plate group  240  will receive fluid at an equal or nearly equal temperature. However, operating valves  216 ,  226  to create a series connection between two cold plates  244  within any cold plate group  240  will cause cooling fluid to reach any higher numbered cold plate groups  240  only after passing through the series-connected cold plates  244 . For example, if third inlet manifold valve  216   c , third outlet manifold valve  226   c , fourth inlet manifold valve  216   d , and fourth outlet manifold valve  216   d  are closed to put second cold plate group  240  in the series flow state, cooling fluid will only reach third cold plate group  240   c  and fourth cold plate group  240   d  after having passed both first cold plate group  240   a  and second cold plate group  240   b . Thus, placing any cold plate group  240  into the series state will create a series flow relationship between that cold plate group  240  and some of the other cold plate groups  240 . 
     Each cold plate group  240  is arranged to cool DIMMs  255  within a respective and like numbered one of first DIMM group  250   a , second DIMM group  250   b , third DIMM group  250   c , and fourth DIMM group  250   d , which can be referred to collectively as DIMM groups  250 . Like cold plate groups  240 , DIMM groups  250  may differ in number in arrangements other than the illustrated example. The connection of multiple cold plate groups  240  along a common flow path, and the above described capability to operate valves  216 ,  226  to create series or parallel connection among different cold plate groups  240  as well as among different cold plates  244  within any cold plate group  240  enables system  200  to be dynamically reconfigured among several different flow paths. System  200  can therefore be adapted to efficiently cool a wide variety of differing combination and quantities of DIMMs  255 . For example, if any cold plate group  240  is placed into the series state, DIMMs  255  having greater cooling needs may be placed in a lower-numbered DIMM group  250  to be cooled by fluid that has not passed through any higher numbered cold plate groups  240 . Likewise, if a total number of DIMMs  255  to be cooled is less than the maximum number of DIMMs  255  that can fit between cold plates  244  in system  200 , DIMM slots located among cold plates  244  of higher numbered cold plate groups  240  may be left empty such that the cooling fluid will pass the empty DIMM slots only after having cooled at least one installed and operating DIMM  255 . 
     In addition to cold plate groups  240 , system  200  may optionally be also include one or more independent cold plates  264 , such as first independent cold plate  264   a  and second independent cold plate  264   b  as shown in the illustrated example. Independent cold plates  264  are not among any cold plate group  240  and are therefore not necessarily associate with any particular valve  216 ,  226 . However, the flow path across independent cold plates  264  may also be affected by the operation of valves  216 ,  226  nonetheless. For example, because independent cold plates  264  are connected to inlet manifold  210  on the same side of inlet opening  211  as cold plate groups  240  and independent cold plates  264  are connected to outlet manifold  220  on the same side of outlet opening as cold plate groups  240 , if all valves  216 ,  226  are open as shown in  FIG.  3   , the flow path from inlet opening  211  to outlet opening  222  will extend through independent cold plates  264  in parallel with the cold plate groups  240 . If third cold plate group  240   c  is converted to the series state while all other cold plate groups  240  remain in the parallel state, cooling fluid will flow through first independent cold plate  264   a  in parallel with first cold plate group  240   a  and second cold plate group  240   b  before flowing through third cold plate group  240   c , and the cooling fluid will flow through second independent cold plate  264   b  in parallel with fourth cold plate group  240   d  after flowing through third cold plate group  240   c.    
     Independent cold plates  264  may optionally be spaced shorter or farther from cold plate groups  240  than adjacent cold plates  244  within cold plate groups  240  are spaced from each other. Independent cold plates  264  may optionally be spaced equally between two cold plate groups  240  as shown in the illustrated example. The possibility to space independent cold plates  264  away from cold plate groups  240  by a different distance than adjacent cold plates  244  are spaced from each other suits independent cold plates  264  for cooling hardware having a different shape and size than the DIMMs  255  cooled by cold plate groups  240  as shown in the illustrated example, though in other examples independent cold plates  264  may be used to cool the same type of hardware as cooled by cold plate groups  240 . 
     In the illustrated example, each independent cold plate  264  is arranged in contact with, directly or through a thermally conductive medium, a respective and like numbered one of first central processing unit (“CPU”)  260   a  and second CPU  260   b , which may be referred to collectively as CPUs  260 . As noted above with regard to DIMMs, CPUs are presented herein by way of example only, so any interaction described between the systems of the present disclosure and CPUs may be equally accurate for components other than CPUs. CPUs  260  are frequently installed near DIMMs  255 , but CPUs  260  have differing form-factors and cooling needs than DIMMs  255 , making the illustrated implementation of system  200  to cool DIMMs  255  and CPUs  260  an example of where system&#39;s  200  combination of cold plate groups  240  and independent cold plates  264  can provide an efficient cooling solution. The above described interaction of valves  216 ,  226  with the flow path among cold plate groups  240  and independent cold plates  264  also enables system  200  to be dynamically adaptable to the wide range of heat load combinations that DIMMs  255  and CPUs  260  together may present. 
       FIG.  4    shows a system  300  wherein multiple inlet manifolds  310  are connected to a single outlet manifold  320 , and independent conduits  364  act as inlet openings. In  FIG.  4    and system  300 , elements, such as outlet manifold  320 , cold plate groups  340  etc., are generally alike to like numbered elements of system  100 , such as outlet manifold  120 , cold plate group  140 , etc., and of system  200 , such as outlet manifold  220 , cold plate groups  240 , etc. except for specifically stated or illustrated differences. As such, certain numerals may be shown in the figures without specific mention herein. 
     System  300  includes a first inlet manifold  310   a  and a second inlet manifold  310   b . First independent cold plate  364   a  carries supply fluid  331  from fluid source  330  into first inlet manifold  310   a , and second independent cold plate  364   b  carries supply fluid  331  into second inlet manifold  310   b . First independent cold plate  364   a  therefore acts as an inlet opening for first inlet manifold  310   a  and second independent cold plate  364   b  therefore acts as an inlet opening for second inlet manifold  310   b.    
     First inlet manifold  310   a  is fluidly connected to outlet manifold  320  by first cold plate group  340   a  and second cold plate group  340   b , and second inlet manifold  310   b  is fluidly connected to second outlet manifold  310  by third cold plate group  340   c  and fourth cold plate group  340   d.    
     First inlet manifold  310   a  includes two distinct portions, and second inlet manifold  310   b  includes two distinct portions. First cold plate group  340   a  and second cold plate group  340   b  connect to different portions of first inlet manifold  310   a  on opposite sides of first independent cold plate  364   a . First cold plate group  340   a  and second cold plate group  340   b  will therefore always receive some fluid directly from first independent cold plate  364   a  in parallel with one another regardless of whether either cold plate group  340   a ,  340   b  is in a series state or a parallel state. Likewise, third cold plate group  340   c  and fourth cold plate group  340   d  are connected to different portions of second inlet manifold  310   b  on opposite sides of second independent cold plate  364   b , so third cold plate group  340   c  and fourth cold plate group  340   d  will always receive some fluid directly from second independent cold plate  364   b  in parallel with one another regardless of whether either cold plate group  340   c ,  340   d  is in a series state or in a parallel state. 
     First cold plate group  340   a , second cold plate group  340   b , third cold plate group  340   c , and fourth cold plate group  340   d  all connected to outlet manifold  320  on a common side of outlet opening  322  and are numbered according to increasing proximity to outlet opening  322 . As such, any cold plate group  340  in the series state, other than first cold plate group  340   a , will receive cooling fluid that has already passed through any lower numbered cold plate groups  340  into outlet manifold  320  in addition to cooling fluid from the corresponding inlet manifold  310 . However, independent cold plates  364  will always receive only supply fluid  331 . System  300  therefore tends to be suitable for applications wherein cooling of CPUs  360  needs to be prioritized over cooling of DIMMs  355 . 
       FIG.  5    shows a system  400  wherein one inlet manifold  410  connects to multiple outlet manifold  420  and independent cold plates  464  act as outlet openings. In  FIG.  5    and system  400 , elements are generally alike to like numbered elements of any of the above described systems  100 ,  200 ,  300 . For example, inlet manifold  410  is generally alike to inlet manifolds  110 ,  210 ,  310 , and cold plate groups  440  are generally alike to cold plate groups  140 ,  240 ,  340 , etc., except for specifically stated or illustrated differences. As such, certain numerals may be shown in the figures without specific mention herein. 
     System  400  includes a first outlet manifold  420   a  and a second outlet manifold  420   b . Inlet manifold  410  is connected to first outlet manifold  420   a  by first cold plate group  440   a  and second cold plate group  440   b  and inlet manifold  410  is connected to second outlet manifold  420   b  by third cold plate group  440   c  and fourth cold plate group  440   d . Inlet manifold  410  receives supply fluid  431  through inlet opening  411 . First independent cold plate  464   a  carries return fluid  432  out of first outlet manifold  410   a  and thereby acts as an outlet opening for first outlet manifold  410   a . Similarly, second independent cold plate  464   b  carries return fluid  432  out of second outlet manifold and thereby acts as an outlet opening for second outlet manifold  410   b.    
     First outlet manifold  420   a  includes two distinct portions, and second outlet manifold  420   b  includes two distinct portions. First cold plate group  440   a  and second cold plate group  440   b  connect to different portions of first outlet manifold  410   a  on opposite sides of first independent cold plate  464   a . First cold plate group  440   a  and second cold plate group  440   b  will therefore always deliver some fluid to first independent cold plate  464   a  in parallel with one another regardless of whether either cold plate group  440   a ,  440   b  is in a series state or a parallel state. Likewise, third cold plate group  440   c  and fourth cold plate group  440   d  are connected to different portions of second outlet manifold  410   b  on opposite sides of second independent cold plate  464   b , so third cold plate group  440   c  and fourth cold plate group  440   d  will always deliver some fluid to second independent cold plate  464   b  in parallel with one another regardless of whether either cold plate group  340   c ,  340   d  is in a series state or in a parallel state. 
     First cold plate group  440   a , second cold plate group  440   b , third cold plate group  440   c , and fourth cold plate group  440   d  are all connected to inlet manifold  410  on a common side of inlet opening  411  and are numbered according to increasing proximity to inlet opening  411 . As such, placing any cold plate group  440  into a series flow state will cause cooling fluid to flow through that cold plate group  440  before reaching any lower numbered cold plate groups  440 . System  400  therefore tends to be suitable for applications wherein cooling of DIMMs  455  needs to be prioritized over cooling of CPUs  460 . 
       FIG.  6    shows a system  500  including multiple subsystems that each include a respective inlet manifold  510  and outlet manifold  520 . In  FIG.  6    and system  500 , elements are generally alike to like numbered elements of any of the above described systems  100 ,  200 ,  300 ,  400 . For example, inlet manifolds  510   a ,  510   b  are generally alike to inlet manifolds  110 ,  210 ,  310 ,  410 , and cold plate groups  540  are generally alike to cold plate groups  140 ,  240 ,  340 ,  440 , etc., except for specifically stated or illustrated differences. As such, certain numerals may be shown in the figures without specific mention herein. 
     System  500  includes two subsystems, with one subsystem being provided by first inlet manifold  510   a , second outlet manifold  520   b , first cold plate group  540   a , second cold plate group  540   b , and first independent cold plate  564 , and the other subsystem being provided by second inlet manifold  510   b , second outlet manifold  520   b , third cold plate group  640   c , fourth cold plate group  540   d , and second independent cold plate  564   b . First inlet manifold  510   a  is not fluidly connected to second inlet manifold  510   b  and first outlet manifold  520   a  is not fluidly connected to second outlet manifold  520   b . A first flow path extending from first inlet opening  511   a  to first outlet opening  522   a  through first and second cold plate groups  540   a ,  540   b  and first independent cold plate  564   a  therefore does not cross a second flow path extending from second inlet opening  511   b  to second outlet opening  522   b  through third and fourth cold plate groups  540   c ,  540   d  and second independent cold plate  564   b . System  500  therefore tends to be suitable for applications wherein cooling of certain hardware should remain entirely unaffected by changes to cooling of other hardware. 
     Systems  200 ,  300 ,  400 ,  500  all present variations of the concept shown in system  100 . The variations within each system  100 ,  200 ,  300 ,  400 ,  500  may all be combined or interchanged in any manner For example, system  200  may be modified by adapting either or both of inlet opening  211  or outlet opening  222  into an independent cold plate. System  200  may also or alternatively by modified by including cold plate groups  240  connected to inlet manifold  210  on opposite sides of inlet opening  211  or connected to outlet manifold  220  on opposite sides of outlet opening  222 . Generally, any system  100 ,  200 ,  300 ,  400 ,  500  may be modified to have any number of cold plate groups and independent cold plates connecting to inlet manifolds on either side of an inlet opening connecting to outlet manifolds on either side of an outlet opening. Further, any system or subsystem within systems  100 ,  200 ,  300 ,  400 ,  500  may include any number of inlet manifolds feeding into any number of outlet manifolds. For example, an inlet may feed into multiple outlet manifolds that, in turn, receive fluid from other inlet manifolds. Moreover, the foregoing examples and variations are equally applicable in conductive heating arrangements, wherein supply fluid enters an inlet manifold at a temperature above the target temperature for objects to be heated by the system and return fluid exits an outlet manifold at a lower temperature. 
     Although the concept herein has been described with reference to particular examples, it is to be understood that these examples are merely illustrative of the principles and applications of the present concept. It is therefore to be understood that numerous modifications may be made to the illustrative examples and that other arrangements may be devised without departing from the spirit and scope of the present concept as defined by the appended claims.