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Title:
FLOW BALANCING IN A FLUID COOLING SYSTEM
Document Type and Number:
WIPO Patent Application WO/2020/021278
Kind Code:
A1
Abstract:
A fluid cooling device for cooling in an electronic system is provided. The fluid cooling device comprises a body, the body comprising an inlet port for receiving a flow of cooling fluid. The fluid cooling device also comprises a plurality of outlet ports each for directing a proportion of the flow of cooling fluid to a part of the electronic system. The inlet port is arranged, in use, to direct a flow of cooling fluid to the plurality of outlet ports along respective outlet paths. The system further comprises at least one biased member contained within the body wherein the biased member is configured to automatically adjust a proportion of the flow of cooling fluid directed to each of the outlet ports.

Inventors:
KOZLOWSKI LUKASZ (GB)
Application Number:
PCT/GB2019/052096
Publication Date:
January 30, 2020
Filing Date:
July 26, 2019
Export Citation:
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Assignee:
KOZLOWSKI LUKASZ (GB)
International Classes:
G06F1/20
Foreign References:
GB885256A1961-12-20
GB1040281A1966-08-24
Other References:
MATT OUSTAD: "Blog - A Quick Look at Dual, Parallel, and Serial Loops", 3 October 2017 (2017-10-03), XP055630808, Retrieved from the Internet [retrieved on 20191010]
LUNCHBOX SESSIONS: "Pressure Compensated Flow Divider", 23 December 2016 (2016-12-23), pages 1, XP054979786, Retrieved from the Internet [retrieved on 20191011]
Attorney, Agent or Firm:
WARREN, Caroline (GB)
Download PDF:
Claims:
Claims

1. A fluid cooling device for cooling in an electronic system, the fluid cooling device comprising:

a body, the body comprising:

an inlet port for receiving a flow of cooling fluid; and

a plurality of outlet ports each for directing a proportion of the flow of cooling fluid to a part of the electronic system;

wherein the inlet port is arranged, in use, to direct a flow of cooling fluid to the plurality of outlet ports along respective outlet paths;

the system further comprising at least one biased member contained within the body wherein the biased member is configured to automatically adjust a proportion of the flow of cooling fluid directed to each of the outlet ports.

2. The device of claim 1 wherein the electronic system comprises a computer system, optionally a desktop computer system, network storage device or server.

3. The device of claim 1 or 2 wherein the fluid cooling device is arranged to adjust the flow of cooling fluid to different parts of the electronic system. 4. The device of any preceding claim comprising two outlet ports.

5. The device of any preceding claim comprising a single biased member.

6. The device of any of claims 1 to 4 comprising a plurality of biased members cooperatively connected.

7. The device according to any preceding claim wherein the at least one biased member is arranged between a first outlet path to a first outlet port and a second outlet path to a second outlet port.

8. The device according to any preceding claim wherein the flow of cooling fluid in an outlet path exerts a force on the at least one biased member causing the biased member to move in a direction away from the biased position.

9. The device according to any preceding claim wherein relative pressure in first and second outlet paths exerts a force on the at least one biased member causing the biased member to move to restrict the flow of cooling fluid in one of the first and second outlet paths.

10. The device of claim 9 wherein the biased member restricts the flow of cooling fluid through the outlet port by reducing the cross sectional area of the path.

1 1. The device according to any preceding claim wherein the biased member is biased to a central positon between two outlet paths.

12. The device according to any of claims 1 to 11 wherein the biased member is biased to an off-centre position between two outlet paths.

13. The device according to any preceding claim wherein the biased member is biased using tensioned springs. 14. The device of any preceding claim further comprising a spring attached to each end of the biased member.

15. The device of claim 14 wherein the springs have the same tension. 16. The device of claim 14 wherein the springs have different pre-selected or pre-set tensions.

17. The device of claim 15 or 16 further comprising adjustment screws configured to adjust the tension of the springs.

18. The device according to any preceding claim further comprising sealing means for sealing the biased member against the body.

19. The device according to any preceding claim wherein the cooling fluid comprises a liquid.

20. The device according to any preceding claim wherein the cooling fluid comprises a gas.

21. The device according to any preceding claim wherein the body is made from a transparent material. 22. The device according to any preceding claim further comprising the cooling fluid, the cooling fluid optionally comprising a water-based or oil-based liquid.

23. A fluid cooling system comprising an array of fluid cooling devices according to any of claims 1 to 22 wherein the output ports of one fluid cooling device are connected to the inlet ports of a plurality of further fluid cooling devices so that the array of fluid cooling devices are arranged in a tree structure.

Description:
Flow Balancing in a Fluid Cooling System

The present application relates to a fluid cooling device for cooling an electronic system, for example a computer system including processors such as a central processing unit (CPU) and/or a Graphics Processing Unit (GPU). Embodiments of the apparatus employ a flow balancing valve in a liquid cooled computer system, but systems using other cooling fluids such as gas are also envisaged. The system can be adopted and scaled for other industrial purposes. In a computer system, there are a number of different components including processors, input and output devices such as the monitor and keyboard, and storage devices. Some of these components, in particular the central processing unit (CPU) and graphics processing unit (GPU), generate a substantial amount of heat in use and are susceptible to damage or failure as a result of overheating. Computer cooling is therefore required to remove the unwanted heat produced by these components in order to maintain the performance of the computer system.

There are a number of different ways to cool the components including air cooling, using fans, passive heat sinks and liquid cooling. In liquid cooling, a liquid, usually water, is pumped round in a sealed circuit through waterblocks, which are mounted on the heat generating components. The liquid is heated by conduction from the heat in the computer components as it passes through the waterblock. The heated liquid flows through the loop to a heat exchanger (typically a radiator with fins), where the heat is removed from the system. As the specific heat capacity and thermal conductivity of water is higher than that of air, liquid cooling can be advantageous over air cooling. It is important that the circuit through which the water flows is sealed against leaks as the components can become damaged by contact with the fluid. The flow rate is important in determining the performance of liquid cooling in serial and parallel loops. The resistance in the circuit directly affects the flow rate. In a serial loop, all the components contribute to the resistance in an additive manner, which can become quite large and consequently hinder the flow rate. The resistance of the system can be reduced by introducing parallel loops.

In a serial system, all parts of the system do receive a flow of fluid. However, in a system employing parallel loops, different pressures in the separate parallel loops can direct flow preferentially to certain components, leaving other components insufficiently cooled. For this reason, most current liquid cooled computer systems are limited to the use of serial loops due to the limitations in control over the flow of liquid in parallel systems. Serial loops place a large amount of strain on the pump and also have a great impact on the overall flow that the pump supplies.

More complex systems, with a plurality of components that need to be cooled, require splitting of the cooling into smaller loops and use multiple pumps to be able to supply enough flow to the individual components. In contrast, switching to a parallel loop system helps to reduce the strain on an individual pump, and can reduce the total number of pumps required to achieve cooling in complex systems. However, different resistance of individual components within the system causes the liquid flow to be distributed unequally and/or incorrectly in order to satisfy individual needs of each component. This can result in uneven cooling of the components which can lead to unwanted heating and failure of those components which do not receive enough cooling fluid.

One of the most common scenarios in computer cooling systems comprises CPU and GPU waterblocks. Most CPU coldplates have much denser fins making them far more restrictive than the GPU units and as a result have a high resistance. In this scenario, naturally more liquid flow would be sent to cool the GPU, which has a smaller resistance, and as a result, we could expect an increase in temperature on the CPU due to the unbalanced flow distribution of the coolant. Also, due to more dense fins in the construction of the CPU, these blocks are exposed to much quicker residue build-up, which further increases the resistance creating further decrease in the flow being supplied to the CPU which then requires more frequent maintenance. The method of balancing the flow provided described herein allows the system to fairly distribute the cooling to components with different resistances and will also help it to run for longer periods without maintenance.

Aspects of the invention are set out in the independent claims and preferred features are set out in the dependent claims. Preferred features may be applied in combination to any aspect of the invention.

There is described herein a fluid cooling device for cooling in an electronic system, the fluid cooling device comprising: a body, the body comprising: an inlet port for receiving a flow of cooling fluid; and a plurality of outlet ports each for directing a proportion of the flow of fluid to a part of the electronic system; wherein the inlet port is arranged, in use, to direct a flow of cooling fluid to the plurality of outlet ports along respective outlet paths; the system further comprising at least one biased member contained within the body; wherein the biased member is configured to automatically adjust a proportion of the flow of cooling fluid directed to each of the outlet ports.

By providing a biased member contained within the body of the fluid cooling device, the proportions of the fluid that flows through each of the paths from the inlet port to the plurality of outlet ports can be automatically adjusted. In particular, the biased member moves automatically, under the influence of the fluid flow through each outlet port, to substantially equalise the fluid pressure at each outlet port. That is, feedback caused by fluid flowing through each of the outlet ports causes the biased member to move, which adjusts the relative sizes or cross sectional areas of the outlet flow paths. The feedback can be caused by the relative temperature or pressure of the fluid within each of the outlet paths. Movement of the biased member allows more fluid to flow to the hotter part of the electronic system, thus enabling a larger amount of cooling fluid to flow to this part of the system to equalise the temperature in the different parts of the electronic system.

In this way, the flow can be balanced so that the component parts along each of the outlet paths can receive a proportion of the cooling fluid, and in particular a constant flow of cooling fluid. The biasing of the biased member ensures that the flow is controlled and can act to adjust the flow as the cooling requirements of the system change in use. The flow of the cooling fluid is divided in accordance with the needs of the components in the parallel loops, which often have different resistances which cause problems with flow distribution and resultant cooling. Balancing the flow advantageously supplies cooling fluid among the parallel loops of the cooling system according to each loops needs or requirements.

The balance between the flows in different part of the system is likely to change a little over time. In particular, as the system ages and residues start to clog waterblocks the relative pressures in the different outlet paths are likely to shift. The present device adjusts itself accordingly to compensate for increased resistance. This can increase longevity and performance of the system before the next maintenance is required.

The skilled person will appreciate that the flow does not have to be evenly balanced in order to effectively cool all parts of the system. However, sufficient balance should be achieved such that there is a constant flow of cooling fluid to all parts of the system and so that flow to one part does not dominate.

This device is advantageous over a device that is controlled using apparatus outside the device, for example, to monitor the flow through the outlet ports or the temperatures of the components that are being cooled, since no monitoring or active adjustment is required. The system is designed to react or respond immediately and without user intervention to the cooling needs of the system as they arise or disappear in use.

The present device seeks to provide a flow balancing valve which controls the flow of fluid (also described below as a liquid), and in particular the amount of liquid flowing down a particular outlet path and being sent to each individual component. Balancing the flow aids cooling of the components, for example according to their individual cooling requirements.

Optionally, the electronic system comprises a computer system, in some embodiments a desktop computer system, network storage device or server. Preferably, the fluid cooling device is arranged to adjust the flow of cooling fluid to different parts of the electronic system.

The flow balancing valve is a fully mechanical device and operates by being sensitive to pressure differences between each outlet and automatically adjusting the flow as required in response to the a pressure imbalance. Pressure differences of liquid in the outlet port chambers connected to each loop act on the central piston [(2)FIG.6j, which causes the piston (2) to shift in the direction away from the high pressure, allowing more flow to the outlet port that requires it, whilst reducing the flow accordingly for the other outlet. Thanks to this action, the overall flow supplied by the pump is being distributed according to need in a fully controlled manner, thus allowing more liquid flow to be sent to more restricted parts of the loop. This action will counterbalance the increased restriction on the different components.

In a system without a flow balancer, a higher proportion of the liquid flows along the loop with the lowest resistance (or the less restrictive component), which causes the other component to receive less cooling. The flow rate to the lower resistance loop is greater than that to the higher resistance loop. The flow balancing valve blocks flow to the low resistance loop so that the resistance along the two paths is more equal and a higher proportion of fluid can be directed to the high resistance loop.

The pressure exerted on the piston by the flow in an output port chamber that has a higher flow rate is less than that exerted by a chamber that has a lower flow rate. In response to the potential difference created by the pressure imbalance, the piston moves towards the chamber with the higher flow rate and reduces the volume of the corresponding output port chamber so that a higher proportion of the flow is directed to the output port that has a lower flow rate, which is output to the higher resistance loop.

The body of the fluid cooling device acts as a housing for the components of the device. The inlet port and plurality of outlet ports can be threaded using standardised threads so as to connect the body to the fluid cooling system with ease. The biased member is configured to be contained within the body so that it can act on the paths that the fluid traverses within it. In one embodiment, the biased member is a piston-like member, however, the skilled person will appreciate that other implementations are also possible. For example, the biased member may comprise a membrane arranged between the outlet paths as described in more detail below. In one embodiment, the body has two outlet ports. In systems with a small number of components for cooling, for example one of each of a GPU unit and a CPU unit, there is no need to split the flow into more than two paths. In some situations, the pumping capacity of the pump may be limited and could lead to insufficient supply of cooling fluid to the components if it is distributed amongst too many loops. Therefore splitting the fluid into more than two loops might lead to a dip in performance. In other embodiments, however, an increased number of outlet ports may be possible. For example, when a pump with a higher capacity is used, or in a more complex system with a greater number of components to be cooled. Optionally, there is a single biased member in the device. In this system, the single biased member performs the act of adjusting the proportion of the flow of cooling fluid directed to each of the outlet ports in the body, in particular by moving between two fluid outlet paths to restrict the flow in one or other of the paths. In other embodiments, there may be a plurality of biased members. For example, there may be a biased member associated with each of a number of paths defined between the inlet and outlet ports. Preferably, said biased members are operably/cooperatively connected so that each is configured to move when the other biased members move.

Preferably, a biased member is arranged between a first outlet path to a first outlet port and a second outlet path to a second outlet port. Advantageously, the biased member can react to the balance of the flow of cooling fluid through the first and second paths when it is arranged to be between them. Other arrangements are also possible. For example, biasing members may be arranged external to the paths (rather than between them) and could be configured to act in a similar manner, for example by providing springs of appropriate relative tensions.

In one embodiment, the flow of cooling fluid in an outlet path exerts a force on the at least one biased member causing the biased member to move in a direction away from the biased position. The cooling fluid exerts a force on the biased member through the build-up of pressure of cooling fluid in the outlet paths. The pressure of the cooling fluid, and the resulting force, is increased for a path that experiences a lower flow rate compared to a higher flow rate. Although the biased member is biased to an initial position, it is configured so as to be able to move from said position, when required, in reaction to the force from the flow of cooling fluid in order to act to balance the flow. A force is exerted on the biased member from each direction that the cooling fluid is in contact with it. In preferred embodiments, the number of paths acting on the biased member is two, the resulting force preferably acting along the same axis of the biased member in opposite directions. If the flow is balanced, there will be no resultant force on the biased member and it will remain in place. However, if one force is greater than the others, the biased member will move.

The biased member is further configured such that it can also be moved in a direction towards the biased position if it has been previously moved away from said biased position. The biased member may be able to move in more than one direction, preferably in a reciprocating manner, and is not confined to move in a single direction away from the biased position once said position has been determined. In certain embodiments, it is arranged to reciprocate linearly from an initial biased position between two outlet port paths as required. In certain embodiments, the force exerted on the biased member is a result of the relative pressure applied to the biased member by the flow of cooling fluid in the respective paths between which it is arranged. The direction away from the biased position in which the biased member moves is optionally towards one of the paths associated with a respective outlet port. Preferably, the outlet port path to which the biased member moves towards is connected to a loop of the parallel system having the greater flow rate. In other embodiments, the force exerted on the biased member could be from a source external to the body that acts to move the biased member to a different location. This force could be exerted by an adjustment or calibration process that may take place before the fluid is flowing through the system or during. Manual or automatic forces could be applied to the biasing member in order to move it.

Preferably, the relative pressure in the first and second outlet paths exerts a force on the at least one biased member causing the biased member to move to restrict the flow of cooling fluid in one of the first and second outlet paths.

The movement of the biased member towards one of the outlet port paths can be arranged such that the biased member restricts the flow of cooling fluid through the outlet port by reducing the cross sectional area of the path. The cross-sectional area of the path is preferably taken perpendicular to the direction of the flow of cooling fluid through said path. The biased member may act to impede the flow of fluid by creating a physical barrier or obstacle across the path. This can be achieved by the movement of the biased member into the path, which interferes with the flow. This action simultaneously allows or helps the flow of the fluid through the other paths with which the biased member is connected to without restriction.

In one embodiment, the biased member is biased to a central positon between two outlet paths. The biasing to a central position allows initially equal flow through the paths between which it is arranged. In other embodiments, the biased member is biased to an off-centre position between two paths. This configuration may be preferable when it is known that the outlet ports lead to loops with a large difference in resistance, for example, when one outlet goes to a GPU and the other to a CPU. It can be preferable in this situation because a larger proportion of the cooling fluid will instinctively flow through the outlet port leading to a loop with the least resistance, so the biasing member can be pre-arranged to restrict the flow through this path.

Preferably, the biased member is biased using tensioned springs. The use of tensioned springs advantageously allows the position of the biased member to be easily moveable and instantly reactive to forces applied to it. It also provides ease of adjustment or adaptation of the system, wherein the tension of the strings can be chosen before use or can also be adapted in use. Preferably, the system comprises a spring attached to each end of the biased member, which may be an elongate biased member. In this arrangement, the springs are attached to opposite ends of the biased member, and are arranged such that the biased member reciprocates linearly between outlet port paths and in so doing acts to block or restrict the path which it moves towards and hence impede the flow within that path.

In one embodiment, the springs have the same tension. In another embodiment, the springs have different pre-selected or pre-set tensions. The choice of the spring tension can be selected or set in a calibration process based on the system to be cooled. If the resistance of the loops is likely to be similar, using the same tension in the springs may be preferable. However, if it is known that the flow will be greater through one of the outlet port paths than the other, caused by different resistances in the loops, or that the flow is likely to be very unevenly distributed, it may be preferable to choose springs with different pre-selected tensions, where a lower tension spring requires less force to extend or compress it and thus is more easily manipulated by the force induced by the flow of cooling fluid.

In another embodiment, adjustment screws can be configured to adjust the tension of the springs as part of a calibration process. Adjustment screws can be used to adjust the tension in the springs through rotation or can be used to shift the location of the biasing position between outlet paths. Tightly coiled springs have a higher tension, whereas less tightly coiled springs exhibit lower tension. By increasing or decreasing the extent to which the springs are coiled or turned, the tension can be controlled.

Optionally, the system can be configured further comprising sealing means for sealing the biased member against the body. This may ensure separation of the flow of cooling fluid in the paths adjacent to the biased member. The seals advantageously stop the flow of cooling fluid between the paths that are connected to different outlet ports. The cooling fluid preferably comprises a liquid; however, it can optionally comprise a gas. Preferably, the liquid used in the system is deionised water with inhibitors added to prevent corrosion and/or biological growth in the cooling loop. Other coolants may also be used including, but not limited to, glycol based ready-mix coolants and nano-fluids.

In certain embodiments, the body is made from a transparent material. A preferable material is acrylic, however, acetal or any other thermally and chemically stable plastics can also be used. Advantageously, this allows a user to see the device in action, and allows calibration to be made with ease and precision. Some users may desire a transparent body simply for aesthetic reasons. In other embodiments, the body can be made from any suitable material and is not limited to being transparent. According to another aspect, there is provided a fluid cooling system comprising an array of fluid cooling devices according to the first aspect wherein the output ports of one fluid cooling device are connected to the inlet ports of a plurality of further fluid cooling devices so that the array of fluid cooling devices are arranged in a tree structure. This can enable the fluid flow path to be split multiple times in a nested fashion so that cooling fluid can be directed to multiple different parts of an electronic system.

Also described and illustrated herein are methods of manufacturing, calibrating and operating the fluid cooling device described.

Figures 1 a and 1 b illustrate different views of an example of the flow balancing valve according to one embodiment;

Figure 2 provides an exploded schematic view of the component parts of the flow balancing valve outside the main body housing according to one embodiment; Figure 3 is an assembled schematic view of the component parts of the flow balancing valve outside of the main body according to one embodiment;

Figure 4 is a complete unit view of the component parts inside the main body according to one embodiment; Figure 5 is a sliced, cross-sectional view of the flow balancing valve along the line A-A according to one embodiment;

Figure 6 is a schematic line drawing of a cross-section of an embodiment of the flow balancing valve;

Figure 7a is view of the main body from the outside according to an embodiment; Figure 7b is a schematic cross-sectional view of the inside of the main body with different zones a-g;

Figure 8a is a view of the piston of one embodiment;

Figure 8b is a view of an embodiment of the piston with optional seals;

Figure 9 is view of the tension springs in one embodiment;

Figure 10 is a view of the adjustment screws according to one embodiment;

Figure 1 1 is a view of the primary seals according to one embodiment;

Figure 12a is a view of the plugs of one embodiment;

Figure 12b is a view of the secondary seals of one embodiment;

Figure 13 is a view of an embodiment of the complete unit featuring a clear acrylic body and piston, stainless-steel springs, nickel plated copper adjustment screws and plugs;

Figure 14 is an example showing a basic liquid cooled computer system in parallel configuration with a flow balancing valve installed in which CPU and GPU waterblocks represent two components of different flow restriction, with the flow balancing valve directing more flow towards the more restrictive component; and Figure 15 is a schematic example for scaling of multiple flow balancing valves system in large units. An exemplary embodiment of the flow balancing device will now be described in detail with reference to the figures.

Figures 1 a and 1 b show an embodiment of the flow balancing unit from two different angles. This flow balancing unit is described in more detail below with reference to the subsequent figures. Flaving a piston [(2)FIG.6j suspended between two springs [(3&4)FIG.6j under tension regulated via two adjustment screws [(5 & 6)FIG.6] allows full control over the calibration process. Endless adjustments to suit different types of loops from the most basic ones, to the most complex systems can be performed. Primary seals [(7&8)FIG.6] enable a user to carry out all the necessary calibrations even when the system is filled and running.

Calibration of the piston involves adjusting its initial position within the internal cylinder feature of the main body and pre-setting the tension of the springs based on the desired or predicted flow rates. The position of the piston dictates the amount of flow through the output port chambers and the output ports. Calibration can be performed before the system has been exposed to a liquid flow, or can also be performed whilst the liquid is flowing.

The end user can use the calibration process to determine how the valve should behave in their system. Calibration can be carried out in a number of different ways; for example both springs can be adjusted equally to compensate for higher or lower performance pumps. If required, springs can be replaced entirely with different tension springs providing an even wider range of tension adjustment. Unequal adjustment will force a piston to favour one of the outlet ports, which may be used to advantage if a user wants to prioritize one of the components/parts of the loop. This device allows a user to operate it in automatic mode as well as providing the benefits of manual adjustments thus allowing full recalibration and fine tuning to suit individual needs. Adjustment can also be achieved by installing springs of varying tensions. It will be appreciated that some embodiments are designed to allow re-adjustment of the tension of the springs even during operation, allowing the user to respond reactively if necessary.

Figure 2 provides an exploded schematic view of the component parts of the flow balancing valve outside the main body housing, with components labelled for consistency with FIG.1 a and the other figures. Figure 3 is an assembled schematic view of the component parts of the flow balancing valve outside of the main body according to one embodiment. Flence, FIG. 3 shows the same components as FIG. 2 but in an assembled state. Figure 4 is a complete unit view of the component parts within the main body according to one embodiment, illustrating in particular the closing plugs in situ.

Figure 5 is a sliced, cross-sectional view of the flow balancing valve along the line A-A according to one embodiment, with the components labelling in accordance with the labelling of FIG. 6, which is described in more detail below.

1. The main body

Figure 7a is a view of the main body from the outside according to an embodiment and Figure 7b is a schematic cross-sectional view of the inside of the main body with different zones a-g, as described in more detail below.

Figure 7b shows the main body (1 ) and the different functional sections and features of a particular non-limiting embodiment. The elements shown are listed below.

(a) Internal cylinder cavity feature to provide housing for the piston (2).

(b) Outlet port chambers.

(c) Un-threaded areas internal to the main body (1 ) to provide a good surface for sealing against leakage using the seals (7 & 8).

(d) Inlet port (13) including Y-junction (16) to feed both outlet chambers (b). In the embodiment illustrated, standard BSPP 1/4” (with a major diameter of 13.157mm) parallel thread (also known as G1/4”) is provided to suit most current standards in cooling computer systems equipment.

(e) Outlet ports (14, 15) with BSP 1/4” thread provided to suit most current standards in cooling computer systems equipment.

(f) Threaded part to fit adjustment screws (5 & 6) allowing calibration process as well as installation of plugs (9 & 10)

(g) Recessed ports to provide flash fitment for the plugs (9 & 10) giving neat and modern look to suit most needs.

The main body (1 ), aside from providing a housing for all the other components, also serves a variety of other functions. This includes providing standardised threads for connecting the inlet (16) [(d)FIG.7b] and outlet [(e)FIG.7b] ports (14, 15) to the rest of the system, a built-in internal cylinder feature [(a)FIG.7b] that provides housing for the piston(2) which acts to balance the flow to the components, as well as an inlet port (13), outlet ports (14, 15) and outlet port chambers [(b)FIG.7b] through which the liquid flows. In the outlet port chambers (b), the pressure of the flow builds up in use and acts on the piston (2) itself.

In a preferred embodiment, use of a transparent material such as acrylic to manufacture the main body (1 ) will provide a clear view of the piston [(2)FIG.6], and is especially helpful during the calibration process. Acetal or any other thermo and chemically stable plastics can also be used which helps provide a high stiffness, low friction, and excellent dimensional stability. However, use of opaque materials in manufacture of the main body (1 ) will reduce users’ ability to visually inspect the part during any calibration process. However, the skilled person will appreciate that the main body (1 ) could be made from a number of different materials including metals such as aluminium or opaque plastics. In an embodiment, in which the whole body is not transparent, a transparent visor is built-in into the main body to provide a view on all the vital parts as required.

The main body can be made of many different materials, however, the use of plastics will greatly reduce the weight when compared to use of metals. The compact design and materials used in manufacturing the main body optimises the ease of production.

2 - Piston/ flow balancing valve

The piston [(2)FIG.6] is one of the main components and provides two main roles. Firstly, it acts as a double sided reciprocating piston between the outlet port chambers. Each end of the piston is exposed to the force of the pressure of the liquid in each of the outlet port chambers [(b)FIG.7b]. Secondly, the piston is designed and placed in such a way that in one embodiment, its body can act as a flow balancing valve that restricts or allows flow through the individual outlet ports (14, 15) as required by the system. In a further embodiment, the piston (2) can fully close or open the outlet ports (14, 15). The current design also provides a pocket/guide for each of the springs (3, 4) to be secured in place on the piston ends.

In most liquid cooled computer systems, which operate at significantly low pressures, no seal is required between the main body [(1 )FIG.6] and piston [(2)FIG.6] to separate the outlet chambers. This allows the liquid to fill the cavity and provide lubrication to ensure smooth operation of the piston without compromising performance. In another embodiment, for high flow and high pressure systems as well as most gas filled systems, installation of additional seals (20) I and II on the piston, as shown in example (FIG.8b), is required.

A variety of materials can be used to produce a piston depending on the application of the device. For the purpose of mainstream computer systems acrylic or plastic would be the preferred choice due to its low weight and low cost. The skilled person would understand that other appropriate materials could be used, such as aluminium.

3 & 4 - Tension springs

Tension springs [(3 & 4)FIG.6], which are also illustrated in FIG. 9, provide a necessary support for the piston [(2)FIG.6] and ensure it remains in the correct position at all times. The tension springs can be selected and can be easily replaced within the body to enable the user to design the system according to specific requirements. Use of different tension springs provides greater ability for pre-calibration of the flow balancing valve depending on the requirements, which can include compensating for pumps with different performance levels or for use in prioritising some of the loops. For example, in a particular embodiment, different springs with different tensions can be used on each side of the piston if it is known that there will be an imbalance in the flow, which can therefore mitigate against an imbalance in the force on the piston, alternatively, springs of the same tension can be calibrated as described below. Anti-corrosion stainless steel springs are a preferred choice of material for the tension springs. Other materials are available. In one embodiment, springs with different tensions can be attached to the two ends of the piston. This is beneficial when there is a large difference between the resistances of the cooling components, as it gives greater control over the extent to which the piston can move. For example, if there is a heavy flow through one output port and a weak flow through the other output port, the pressure exerted on the piston on the end that experiences the heavier flow will be larger and the piston could be forced closed on the side with the weak flow. Using a higher tension of the springs could help to maintain the central position of the piston in these situations.

5 & 6 - Adjustment screws

Adjustment screws [(5 & 6)FIG.6, which are also illustrated in Fig. 10, provide the ability to calibrate the flow balancing valve accordingly to the needs of the system. By adjusting the screws [(5 & 6)FIG.6] , the tension of the springs [(3 & 4)FIG.6] can be reduced or increased, and the piston [(2)FIG.6j is moved in the desired direction. This process provides a calibration of the flow balancing valve and provides an excellent tool for controlling the flow to meet the requirements of any system. A variety of materials can be used to produce these parts depending on the application of the device. In one embodiment, for the use in mainstream computer systems, plastic could be used due to it low weight and low cost. In a preferred embodiment, however, use of bare/plated copper or brass and aluminium is the preferred choice. These materials provide much greater resistance to damage during the calibration procedures.

7 & 8 - Primary seals

Seals [(7 & 8)FIG.6], also illustrated in FIG. 11 , prevent the liquid from leaking during the calibration. They enable the user to fine tune their system in working conditions without the worry of the liquid leaking. Chemically stable rubber or silicon based seals are the preferred material of these seals, however, other materials can also be used. 9 & 10 - Plugs

Plugs [(9 & 10)FIG.6], also illustrated in FIG. 12a, provide a permanent seal in normal use during operation of the device, after all the necessary calibration is finished and no further access to the adjustment screws [(5 & 6)FIG.6] is required.

In one embodiment, for the purpose of mainstream computer systems, plastic could be used due to its low weight and low cost. In a preferred embodiment, however, use of bare/plated copper or brass and aluminium is the prefered choice. These materials provide much greater resistance to damage during any calibration procedures or maintenance, however, other materials may be used.

11 & 12 - Secondary seals

The secondary seals [(1 1 & 12)FIG.6], illustrated in FIG. 12b, provide a permanent seal between the main body [(1 )FIG.6] and the plugs [(9 & 10)FIG.6] when access to the unit’s internal components isn’t required. Chemically stable rubber or silicon based seals are the preferred material, however, other materials may be used.

FIG. 13 shows a computer generated picture of a unit according to one embodiment. Featuring clear acrylic body (1 ) and piston (2), stainless-steel springs (3, 4), nickel plated copper adjustment screws (5, 6) and plugs (9, 10).

FIG. 14 shows a schematic diagram of a basic liquid cooled computer system in parallel configuration with a flow balancing valve installed. In this scenario CPU (30) and GPU (40) waterblocks represent two components of different flow restriction. The components are not limited to CPU and GPU units, many other arrangements are possible. The flow balancing valve will direct a greater amount of the flow towards the more restrictive component. The diagram also includes a radiator (50) for radiating heat from the cooling fluid, a reservoir (60) of cooling fluid, and a pump (70) for driving fluid around the system.

In an alternative embodiment, the biased member may comprise a membrane in place of the piston. The membrane would be arranged between the two outlet flow paths and would move, in the same way as the piston, to restrict the flow in one of the paths, depending on the relative pressure in the fluid of the two paths. The membrane could be arranged in a central chamber between the fluid flow paths.

The membrane could have a large surface area and would provide greater sensitivity to pressure changes in the system than the piston embodiment. It would also provide a seal between the two output chambers or paths.

Such an embodiment may be particularly useful where fine-tuning of flow balancing between the output paths is required, particularly where the size of the flow balancing unit is not restricted, since the piston embodiment tends to enable a more compact design than the membrane embodiment.

FIG.15 shows a schematic example for scaling of multiple flow balancing valves system in large units in a tree-like structure. As illustrated in FIG. 10, the whole unit can also be easily scaled up for commercial purposes where big industrial pumps are required and operate at high flow and pressures. In particular, for more complex systems, scaling can be achieved by using multiple flow balancing valves units (200, 300, 400, 500, 600, 700) where each (parent) unit will control next sub units in pattern of 1 -2-4-8... and so on as illustrated in FIG.10. The embodiment of FIG. 15 may be useful for example in large-scale server systems as well as supercomputer arrays where big industrial grade pumps are being used to cool components and harvest waste energy at the same time. The device described above could be scaled up to withstand greater pressures. For example, in a particular embodiment, one large pump could supply liquid to 8 racks/cabinets. Multiple scaled up versions of the device described above would be provided in a tree like configuration to reach eight outputs in total. From there the system would supply each of the eight racks. Inside each rack small compact versions of my device could be used for further control over the flow supplied to multiple CPUs/GPUs. The flow balancing valve can be implemented to reduce the need for multiple pumps in complex systems. This can reduce the initial build cost, as well as future maintenance and cost by not having to replace the physical pumps. The improvement to the efficiency of the system can also decrease running cost.

In other embodiments, the whole unit can be adjusted and adapted to work within non-liquid flow environments, for example using a cooling gas such as air. A cooling fluid comprising a suspension of liquid in gas or a fluid comprising a suspension of solid particles (for example nanoparticles) in a liquid is also envisaged.