Arrangement and method for controlling the flow in a cooling circuit

Abstract

An arrangement for controlling the flow in a cooling circuit (10'), the cooling circuit comprising a first piping (12) allowing a cooling fluid to flow towards to and away from an element to be cooled (14), a second piping (16) in fluid connection with said first piping (12), said second piping (16) allowing cooling fluid to flow towards to and away from a cooling element (18), a bypass line (20) allowing the cooling fluid to bypass the second piping (16) to circulate in the first piping (12), and a first pump (22) for circulating the cooling fluid in the first piping (12), the arrangement further comprising a second pump (26) for circulating the cooling fluid in the second piping (16), and a control device for controlling the power of the second pump (26).

Description

[0001] ARRANGEMENT AND METHOD FOR CONTROLLING THE FLOW IN A COOLING CIRCUIT

[0002] TECHNICAL FIELD

[0003] The invention relates to an arrangement and a method for controlling the flow in a cooling circuit.

[0004] TECHNICAL BACKGROUND

[0005] In a cooling circuit, a cooling fluid, often but not necessarily based on water with or without additives, flows towards to and away from an element to be cooled. In the vicinity of the element to be cooled, heat energy is transferred from the element to be cooled to the cooling fluid, thus reducing the temperature of the element to be cooled. As the cooling fluid flows, it transports the heat energy away from the element to be cooled to an element to be heated, hereinafter called cooling element, which in turn cools down the fluid so that it can flow again towards the element to be cooled.

[0006] An element to be cooled can be almost anything, but a typical example is a mechanical or electrical component, e.g. a part of a projector, that in use must be cooled to prevent damage due to overheating. Likewise, the cooling element can be anything like a heat sink that has litle or no problems with overheating. in a particular type of cooling circuit, the cooling circuit comprises a first piping allowing the cooling fluid to flow towards to and away from the element to be cooled, a second piping in fluid connection with said first piping, said second piping allowing cooling fluid to flow towards to and away from a cooling element, a bypass line allowing the cooling fluid to bypass the second piping to circulate in the first piping, and a pump for circulating the cooling fluid in the first piping. By controlling the amount of cooling fluid flowing through the bypass line and thus bypassing the second piping, it is possible to control the temperature in the cooling circuit. This is required as some elements to be cooled have a preferred range of operating temperatures and should thus neither become too hot nor too cold. On the other hand, for security purposes it shall be ensured that there is a constant flow of cooling fluid during operation of these elements, so that the pump for circulating the cooling fluid in the first piping is always operating with a certain power and / or at a certain flow rate, and the temperature in the cooling circuit is controlled via actuated three-way-valves that direct more or less fluid into the second piping respectively into the bypass line, while keeping the flow in the first piping substantially constant. An example of such cooling circuit is shown in Fig. 1.

[0007] While such arrangements are widely used, it has turned out that using actuable three-way-valves has certain drawbacks. Actuable three-way-valves have a rather slow response time, often in the range of about 30 to 120 s before they reach the intended opening / closing position to adjust the flow in the bypass line and the second piping. Moreover, they need a specific electronic infrastructure, e.g. require a certain supply voltage and a control logic that may not be yet readily available in a mounting situation, e.g. at a projector, where an element shall be cooled. Besides, reliable three-way-valves together with their actuators can be rather expensive compared to other parts of a cooling circuit. Also, some three-valve-valves are sensitive towards their operation orientation, i.e. they may not work properly if used upside down, which can be problematic if the element to be cooled is a mobile component that in principle can be operated in many different mounting positions. DISCLOSURE OF THE INVENTION

[0008] The invention aims solving the problems associated with the use of three-way- valves in a cooling circuit of the aforementioned type comprising a first piping, a second piping, and a pump by providing an arrangement and a method for controlling the flow in such cooling circuit.

[0009] The problems are solved by an arrangement according to claim 1 respectively a method according to claim 8. Advantageous embodiments are defined in the dependent claims.

[0010] A basic concept of the invention is replacing the three-way-valve with a further pump, namely a pump arranged in the second piping before or after the cooling element. As this further pump is arranged in the second piping, it is hereinafter called the second pump, while the pump arranged in first piping is hereinafter called the first pump.

[0011] Using a second pump surprisingly has numerous advantageous effects. Prices of such pumps for a specific cooling circuit are often significantly lower than those of a actuable three-way-valves for the same cooling circuit, in the circuit. A big advantage is the response time: if the second pump is e.g. a centrifugal pump, its response time usually below 10 s, and there are often no restrictions regarding operating orientation.

[0012] Further advantages and details of the invention will become apparent from the following detailed description of preferred embodiments in conjunction with the drawing, which comprises seven figures.

[0013] BRIEF DESCRIPTION OF THE DR WING

[0014] Fig. 1 is a schematic drawing showing an arrangement for controlling the flow in a cooling circuit according to the prior art. Fig. 2 is a schematic drawing showing an arrangement for controlling the flow in a cooling circuit according to one embodiment of the invention.

[0015] Fig. 3 is a diagram showing the relationship between different flow rates.

[0016] Fig. 4 shows a connecting module according to one embodiment of the invention.

[0017] Fig. 5 shows a first element of the connecting module according to Fig. 4.

[0018] Fig. 6 shows a second element of the connecting module according to Fig. 4.

[0019] Fig. 7 shows a sectional view of the connecting module according to Fig. 4.

[0020] DESCRIPTION OF PREFERRED EMBODIMENTS

[0021] Fig. 1 is a schematic drawing showing an arrangement for controlling the flow in a cooling circuit, denoted in its entirety by 10, according to the prior art. The cooling circuit 10 comprises a first piping 12 (for explanatory purposes indicated by a dashed rectangle), which allows the cooling fluid to flow towards to and away from an element 14 to be cooled, a second piping 16 (for explanatory purposes indicated by another dashed rectangle) in fluid connection with said first piping 12, said second piping 16 allowing cooling fluid to flow towards to and away from a cooling element 18, a bypass line 20 allowing the cooling fluid to bypass the second piping 16 to circulate in the first piping 12, and a pump 22 for circulating the cooling fluid is provided in the first piping 12. In this and in the other schematic drawing (Fig. 2), the pipes forming the piping 12, piping 16, and the bypass line 20 are represented by arrows, which also indicate the direction of the flow of cooling fluid.

[0022] To control the amount of fluid flowing through the bypass line 20, thus bypassing the second piping 16, an actuated three-way-valve 24 is provided at a junction between the first piping 12 and the second piping 16. Actuated three-way-valve 24 has three branches, one connected to the first piping 12, one connected to the second piping 16, and one directed to the bypass line 20. Actuated three-way-valve 24 directs more or less fluid into the second piping 16 respectively into the bypass line 20, while keeping the flow in the first piping substantially constant. By controlling the amount of fluid flowing through the bypass line 20, it is possible to control the temperature in the cooling circuit 10 and in particular in the first piping 12. Note that as used herein the term "in fluid connection" denotes the fact that the first piping 12 and the second piping 16 are connected to allow fluid in principle to flow from one piping into the other, while of course no such flow may occur when the branch of the three-way-valve 24 leading to the second piping 16 is closed.

[0023] Fig. 2 is a schematic drawing showing an arrangement for controlling the flow in a cooling circuit, denoted in its entirety by 10', according to the invention. As the cooling circuit 10' has in principle the same structure as the cooling circuit of Fig. 1 , the same reference number have been used to denote elements corresponding to those shown in Fig. 1. Again, for explanatory purposes a first piping 12 and a second piping 16 are indicated by dashed rectangles, and all pipes forming piping 12, piping 16, and a bypass line 20 are represented by arrows, which also indicate the direction of the flow of cooling fluid. The first piping 12 allows a cooling fluid to flow towards to and away from an element 14 to be cooled, and the second piping 16, which is in fluid connection with said first piping 12, allows cooling fluid to flow towards to and away from a cooling element 18. A bypass line 20 allows the cooling fluid to bypass the second piping 16 to circulate in the first piping, and a first pump 22 is provided in the first piping 12 for circulating the cooling fluid in the first piping 12.

[0024] In some embodiments of the present disclosure, in addition to the first pump 22, a second pump 26 for circulating the cooling fluid in the second piping 16, and a control device (not shown in the drawing) for controlling the power of the second pump are provided, rendering an actuated three-way-valve void. By employing a second pump 26 arranged in the second piping 16, it becomes easily possible to control the temperature in the first piping 12 by controlling the second pump 26. Again, "in fluid connection" denotes the fact that the first piping 12 and the second piping 16 are connected to allow fluid in principle to flow from the first piping 12 into the second piping 16, while no such flow will occur when the second pump 26 is turned off.

[0025] In an embodiment of the arrangement, the first pump 22 and the second pump 26 are of the same type, in particular a type of centrifugal pump. This has several advantages. For example, using the same type of pump means that the electric infrastructure for the second pump 26 is already present as it is needed anyway for the first pump 22. Pumps and in particular centrifugal pumps have a fast response time compared to that of actuable three-way-valves, and are generally not sensitive towards their orientation during operation.

[0026] Fig. 3 is a schematic diagram showing the principal relationship between three different flow rates in operation of a cooling circuit according to the invention. The abscissa (x-axis) 28 represents the "power" of the second pump 26, which can be given in any suitable unit such as e.g. the current supplied to the pump or the pump speed, while the ordinate (y-axis) 30 represents the flow rate of cooling fluid. Line 32 indicates the flow of cooling fluid in the first piping, line 34 indicates the flow of cooling fluid in the second piping, and line 36 indicates the flow of cooling fluid in the bypass line. In operation of a cooling circuit according to the invention, the first pump ensures a constant flow of cooling fluid in the first piping, which is hence in principle constant as indicated by line 32. If the second pump is turned off, in principle no fluid flows in the second piping and all the fluid coming from the first piping flows through the bypass line, while with increased power more and more fluid flows in the second piping (as indicated by line 34), and fewer and fewer fluid flows though the bypass line (as indicated by line 36). In some embodiments, the flow diameter of the bypass line may be chosen to be significantly smaller (e.g. three to six times smaller) than the flow diameter of the first and second piping, which may assist ensuring that in case the second pump is provided with sufficient power, basically all cooling fluid coming from the first piping is directed through the second piping and thus cooled. However, in other embodiments the flow diameter of the bypass line may be chosen to substantially or entirely the same as the flow diameter of the first and the second piping, which advantageously allows to use the same tubes for forming the cooling circuit.

[0027] Figs. 4 to 7 show a connecting module, denoted in its entirety by 40 in Fig. 4 and 7, and its main parts according to one embodiment of the invention. The connecting module is designed to establish the fluid connection between the first piping 12 and the second piping 14.

[0028] The connecting module 40 is basically comprised by two elements 42 and 44, in assembled state mounted together by screws 46 (two provided with reference numbers in Fig. 5) and respective threaded bores 48 (two provided with reference numbers in Fig. 6). However, the connecting module 40 may comprise any fastening mechanism capable of fastening elements 42 and 44. The module has four ports 50, 52, 54, and 56. As shown in the sectional view of Fig. 7, ports 42 and 44 are connected via internal conduit 58, and ports 46 and 48 are connected via internal conduit 60. From both conduits 58 resp. 60, a bypass line 62 resp. 64 branches off, forming in the assembled state, i.e. when elements 42 and 44 are atached to each other, a single bypass line (20 in Fig. 2). The flow diameter of the bypass line formed by the bypass lines 62 and 64 is significantly smaller than the flow diameter of the conduits 58 and 60 and the general flow diameter of the first and second piping. In some further embodiments, a sealing material 80 is used in the junction between respective surfaces of elements 42 and 44 to prevent the cooling fluid flowing out between the respective surfaces of elements 42 and 44.

[0029] The connecting module 40 forms the "interface" between the first and the second piping and may for example be integrated in the cooling circuit schematically shown in Fig. 2 such that port 52 forms an inlet for cooling fluid coming from the first piping (12 in Fig. 2) as indicated by arrow 66, port 50 forms an outlet for cooling fluid to the second piping (16 in Fig. 2) as indicated by arrow 68, port 54 forms an inlet for cooling fluid from the second piping as indicated by arrow 70, and port 56 forms an outlet for cooling fluid to first piping as indicated by arrow 72.

[0030] In some embodiment of the arrangement, the control device (not shown) is in communication with at least one temperature sensor (not shown) measuring the temperature of the element (14 in Fig. 2) to be cooled and / or the temperature of the cooling fluid in the first piping (12 in Fig. 2), in particular after the element to be cooled. This allows automatic control of the temperature in the first piping and thus the "cooling power" of the cooling circuit 10'. Another option is a temperature sensor at the connecting module 40, measuring the temperature of the mixed flow. If this sensor is able to communicate with the control device, the cooling power of the cooling circuit can be automatically controlled via the second pump (26 in Fig. 2).

[0031] In some further embodiment of the arrangement, the control device (not shown) is in communication with exactly one temperature sensor (not shown) measuring the temperature of the element (14 in Fig. 2) to be cooled or the temperature of the cooling fluid in the first piping (12 in Fig. 2), in particular after the element to be cooled. This has the advantage that the set-up of the arrangement can be kept very simply and and cost efficient.

[0032] The present disclosure also provides for a method for controlling the flow in a cooling circuit such as the one shown in Fig. 2, said cooling circuit comprising a first piping allowing a cooling fluid to flow towards to and away from an element to be cooled, a second piping in fluid connection with said first piping, said second piping allowing cooling fluid to flow towards to and away from a cooling element, a bypass line allowing the cooling fluid to bypass the second piping to circulate in the first piping, a first pump for circulating the cooling fluid in the first piping, and a second pump for circulating the cooling fluid in the second piping, wherein the method comprises controlling the power of the second pump to adjust the amount of cooling fluid flowing through the bypass line. in some embodiment of the method, the first pump is operated with constant power and / or at constant flow rate and the second pump is operated with variable power depending on the desired temperature of the cooling fluid flowing towards the element to be cooled.

[0033] In some further embodiment of the method, the power of the second pump is controlled in dependence of the temperature of the cooling fluid in the first piping, or of the element to be cooled, or both.

[0034] Generally, when the second pump is off, the resistance of the second piping is much higher than that of the bypass line, so all cooling fluid goes through the bypass. When the pump power is increased, some cooling fluid will start flowing through the second piping and less cooling fluid will flow through the bypass line. When the pump power is increased to the point where the flow in the second piping is equal to the flow in the first piping flow, the flow through the bypass goes towards zero.

[0035] Therefore, the arrangement can have substantially 100% flow through the bypass (pump off), substantially 0% flow through the bypass (pump max), and any value in between (see also Figure 3).

[0036] While at present centrifugal pumps are preferred, alternative pump types such as, e.g., positive displacement pumps, peristaltic pumps, or diaphragm pumps could in certain instances, depending of the overall design an of the cooling circuit and its specific application be used as well.

[0037] To control the pump speed in particular of the second pump (the first pump will in a typical use case be run at constant speed / flow rate), controls such as variable frequency drives (VFDs) or pulse-width modulation (PWM) control, can be used to more precisely manage the flow rate and temperature within the cooling circuit.

[0038] In addition to temperature sensors, flow sensors could be integrated into the cooling circuit to provide real-time data on the flow rate through the first and the second piping, enhancing the ability to maintain desired operating conditions. For certain applications, redundancy features, such as a backup pump or an automatic switchover system, could be employed to ensure continuous operation of the cooling circuit in the event of a pump failure. An integrated control system with a user interface that allows for manual adjustments, preset temperature profiles, or remote monitoring and control could be employed to enhance the functionality of the cooling circuit.

[0039] Depending on the amount of heat absorbed by the cooling element, employing an energy recovery system that captures waste heat from the cooling element and repurposes it for other uses could employed to improve the overall energy efficiency of the cooling circuit.

[0040] LIST OF REFERENCE NUMBERS

[0041] 10 Cooling circuit (prior art)

[0042] 10' Cooling circuit (proposed invention)

[0043] 12 First piping

[0044] 14 Element to be cooled

[0045] 16 Second piping

[0046] 18 Cooling element

[0047] 20 Bypass line

[0048] 22 First pump

[0049] 24 Three-way valve

[0050] 26 Second pump

[0051] 28 Abscissa (x-axis)

[0052] 30 Ordinate (y-axis)

[0053] 32 Flow rate in first circuit

[0054] 34 Flow rate in secondary circuit

[0055] 36 Flow rate in bypass line

[0056] 40 Connecting module

[0057] 42 First element of the connecting module

[0058] 44 Second element of the connecting module 46 Screws for mounting the connecting module elements

[0059] 48 Threaded bores

[0060] 50 Port (outlet port)

[0061] 52 Port (inlet port)

[0062] 54 Port (inlet port)

[0063] 56 Port (outlet port)

[0064] 58 Internal conduit

[0065] 60 Internal conduit

[0066] 62 Bypass line

[0067] 64 Bypass line

[0068] 66 Arrow indicating flow from first piping

[0069] 68 Arrow indicating flow to second piping

[0070] 70 Arrow indicating flow from second piping

[0071] 72 Arrow indicating flow to first piping

Claims

1. Arrangement for controlling the flow in a cooling circuit (10'), the cooling circuit comprising a first piping (12) allowing a cooling fluid to flow towards to and away from an element to be cooled (14), a second piping (16) in fluid connection with said first piping (12), said second piping (16) allowing cooling fluid to flow towards to and away from a cooling element (18), a bypass line (20) allowing the cooling fluid to bypass the second piping (16) to circulate in the first piping (12), and a first pump (22) for circulating the cooling fluid in the first piping (12), characterized by comprising a second pump (26) for circulating the cooling fluid in the second piping (16), and a control device for controlling the power of the second pump (26).

2. The arrangement according to claim 1 , characterized in that the first pump (22) and the second pump (26) are of the same type, in particular a type of centrifugal pump.

3. The arrangement according to claim 1 or 2, characterized in that the flow diameter of the bypass line (20) is substantially the same as the flow diameter of the first (12) and second piping (16).

4. The arrangement according to claim 1 or 2, characterized in that the flow diameter of the bypass line (20) is significantly smaller than the flow diameter of the first (12) and second piping (16).

5. The arrangement according to one of claims 1 to 4, wherein the control device (54) is in communication with at least one temperature sensor (56) measuring the temperature of the element to be cooled (14) and / or the temperature of the cooling fluid in the first piping (12) after the element to be cooled (14).

6. The arrangement according to claim 5, characterized in that the control device (54) is in communication with exactly one temperature sensor (56) measuring the temperature of the element to be cooled (14) or the temperature of the cooling fluid in the first piping (12) after the element to be cooled (14).

7. The arrangement according to one of claims 1 to 6, characterized in that the bypass line (20) and the fluid connection between the first piping (12) and second piping (16) are established via a connecting module (40).

8. The arrangement according to claim 7, characterized in that the connecting module (40) comprises a first element (42) and a second element (44) mountable to each other and defining there between an internal bypass line (62, 64) and internal conduits (58, 60) for establishing fluid communication between the first piping (12) and the second piping (16).

9. A method for controlling the flow in a cooling circuit, said cooling circuit comprising a first piping allowing a cooling fluid to flow towards to and away from an element to be cooled, a second piping in fluid connection with said first piping, said second piping allowing cooling fluid to flow towards to and away from a cooling element, a bypass line allowing the cooling fluid to bypass the second piping to circulate in the first piping, a first pump for circulating the cooling fluid in the first piping, and a second pump for circulating the cooling fluid in the second piping, the method comprising controlling the power of the second pump to adjust the amount of cooling fluid flowing through the bypass line.

10. The method according to claim 9, wherein the first pump is operated with constant power and / or at constant flow rate and wherein the second pump is operated with variable power depending on the desired temperature of the cooling fluid flowing towards the element to be cooled.

11. The method according to claim 9 or 10, wherein the power of the second pump is controlled in dependence of the temperature of the cooling fluid in the first piping, or of the element to be cooled, or both.

12. The method according to one of claims 9 to 11 , wherein the first pump is operated at a constant power and / or at a constant flow rate.

13. The method of according to one of claims 9 to 12, wherein the power of the second pump is varied based on a temperature measurement obtained from at least one temperature sensor.

14. The method of claim 13, wherein the at least one temperature sensor measures at least one of the temperature of the cooling fluid in the first piping after the element to be cooled, and the temperature of the element to be cooled.

15. The method according to one of claims 9 to 14 further comprising controlling the second pump in response to a control signal from a control device, the control device configured to adjust the power of the second pump based on the desired temperature of the cooling fluid flowing towards the element to be cooled.

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