System and method for transferring heat from a heat producer to a heat consumer and for transferring cooling to the heat producer

Abstract

The present invention relates to a heat-and-cooling system (1) for transferring heat from a heat producer (11) to a heat consumer (21) and for transferring cooling to the heat producer (11), wherein the heat-and-cooling system (1) comprises: - a heat-producing section (10) comprising one or more heat producers (11) configured to provide a first liquid (16) at a first heat-outlet (12) and receive a return-liquid at a return inlet (13); - a heat-consuming section (20) comprising a consumer return (23) and a second heat-outlet (22) wherein the second heat-outlet is configured for transferring a second liquid (26) to a heat consumer (21) and the consumer return is configured for receiving a return-liquid from the heat consumer (21); and - a heat-transferring section (30) arranged between the heat-producing section (10) and the heat-consuming section (20), wherein the heat-transferring section comprises: - a passive liquid-to-liquid heat exchanger (40) comprises at least two inlets (41,43) and outlets (42,44) and is configured to transfer heat from the first liquid (16) to the second liquid (26), wherein the first fluid flows through the first inlet (41) and the first outlet (43) and the second fluid flows through the second inlet (43) and the second outlet (44); and - a series of heat pumps comprising at least one or more heat pumps configured for transferring heat from the first liquid (16) to the second liquid (26), wherein a first heat pump (50) is downstream to the passive liquid-to-liquid heat exchanger (40), wherein the first liquid flows to the return inlet (13) and the second liquid flows to the second heat-outlet (22).

Description

[0001] System and method for transferring heat from a heat producer to a heat consumer and for transferring cooling to the heat producer

[0002] Field of the Invention

[0003] The present invention relates to a system and method for transferring heat from a heat producer to a heat consumer and for transferring cooling to the heat producer.

[0004] Background of the Invention

[0005] Heat consumers may be provided with one or more sources of excess heat from a heat producer, wherein the excess heat is re-used as heating for the heat consumer. The re-use of excess heat is advantageous in terms of being environmentally friendly, because the excess heat may otherwise be exhausted into the atmosphere.

[0006] Heat consumers, such as district heating, generally have strict requirements for temperature of the received heat and the time in which it requires to receive the heat, i.e. the heat should generally be readily available without delay. Delay, or a lack of heat supply entirely, means that expensive back-up solutions are required, which is not feasible when designing e.g., a district heating network.

[0007] A heat producer, such as a data centre, generally also has strict requirements in terms of requiring a stable supply of cooling and / or an ability to off-load excess heat, in order to achieve an energy efficient cooling system where energy spent on cooling is recuperated in some way.

[0008] Many attempts have been made to recuperate the energy spent on cooling industrial processes which produce excess heat, such as data centres, however none of the available solutions achieve a high energy efficiency nor a high degree of flexibility in terms of being able to deliver heat to the heat consumer and cooling to the heat producer within the strict requirements.

[0009] There is yet still an ambition to achieve a sustainable design, wherein the joint production of excess heat from an industrial process and the return flow of liquid from heat consumers are incorporated so that energy consumption for both the industrial process, in terms of cooling, and the heat consumers, in terms of heating, are reduced compared to if the two were to produce cooling and heat, respectively, standalone.

[0010] Object of the Invention One objective of the present disclosure is to achieve a system capable of efficiently transferring excess heat from a heat producer to a heat consumer.

[0011] One further objective is to provide a highly flexible system capable of providing heat and cooling to both a heat consumer and a heat producer on demand. Le. in one instance, only cooling may be transferred to the heat producer; in another instance, only heat may be transferred to the heat consumer; or in another instance, both heat is transferred to the heat consumer and cooling is transferred to the heat producer.

[0012] Description of the Invention

[0013] One objective of the invention is achieved by a heat-and-cooling system for transferring heat from a heat producer to a heat consumer and for transferring cooling to the heat producer, wherein the heat-and-cooling system comprises:

[0014] - a heat-producing section comprising one or more heat producers, configured to provide a first liquid at a first heat-outlet and receive a return-liquid at a return inlet;

[0015] - a heat-consuming section comprising a consumer return and a second heat-outlet, wherein the second heat-outlet is configured for transferring a second liquid to a heat consumer and the consumer return is configured for receiving a return-liquid from the heat consumer; and

[0016] - a heat-transferring section arranged between the heat-producing section and the heatconsuming section, wherein the heat-transferring section comprises:

[0017] - a passive liquid-to-liquid heat exchanger comprises at least two inlets and outlets and is configured to transfer heat from the first liquid to the second liquid, wherein the first fluid flows through the first inlet and the first outlet and the second fluid flows through the second inlet and the second outlet;

[0018] - a series of heat pumps comprising at least one or more heat pumps configured for transferring heat from the first liquid to the second liquid, wherein a first heat pump is downstream to the passive liquid-to-liquid heat exchanger, wherein the first liquid flows to the return inlet and the second liquid flows to the second heat-outlet.

[0019] The flow of liquid generally flows from an upstream position to a downstream position, e.g. the first liquid flows from the heat producer to the passive liquid-to-liquid heat exchanger and the second liquid flows from the liquid-to-liquid heat exchanger to the series of heat pumps.

[0020] In one aspect, the return-liquid may circulate through the heat producer and be used as a cooling liquid or the cooling stored in the return-liquid may be transferred to the heat producer e.g. directly or through a liquid-to-liquid heat exchanger or liquid-to-air heat exchanger pertaining to the heat producer. Eventually, as the return-liquid has circulated by or through the heat producer, it becomes the first liquid which is transferred away from the heat producer, i.e. , in a downstream direction.

[0021] In one aspect, the return-liquid may not need to be a particularly cool temperature to be used as cooling for the heat producer, i.e. a temperature above an ambient temperature (where ambient temperature is e.g. approximately 16 to 26 degrees Celsius) may still be used for cooling purposes. One advantage of providing a warmer temperature for the return-liquid is that the first liquid transferred out of the heat producer is at a higher temperature, which in turn increases the efficiency of the heat-and-cooling system as less energy is required to provide a higher temperature to the second liquid.

[0022] The heat producer may be data center, a hospital or any industrial plants such as a potato flour factory or a sugar factory. In general, the heat producer may be any one or more larger scale buildings and / or industrial processes which produce excess heat and require cooling in return. One advantage of connecting such one or more heat producers to the heat-producing section is that the heat-and-cooling system may utilise the excess heat produced by the heat producers efficiently while also providing cooling to the heat producers in an efficient manner.

[0023] The heat consumer may be district heating, i.e. a network for providing heating to private and public consumers and / or industry, or any other buildings or processes which may require to receive heat and return a return-liquid to the consumer return of the heat-consuming section. Hence, by transferring excess heat from the heat producer to the heat consumer, the heat- and-cooling system provides and efficient and environmentally friendly solution to re-use excess heat and provide cooling.

[0024] A first stage of the heat transfer may be provided by the passive liquid-to-liquid heat exchanger, which is advantageous because the passive liquid-to-liquid heat exchanger efficiently transfers heat from the first liquid to the second liquid. This may be achieved by transferring the first liquid to the first inlet of the passive liquid-to-liquid heat exchanger, wherein the first liquid flows through the passive liquid-to-liquid heat exchanger to a first outlet. Meanwhile, the second liquid is transferred from the consumer return to the second inlet, wherein the second fluid flows through the passive liquid-to-liquid heat-exchanger to the second outlet.

[0025] A second stage of the heat transfer may be provided by the series of heat pumps, which is achieved by transferring the first liquid from the first outlet of the passive liquid-to-liquid heat exchanger downstream to the first heat pump in the series of heat pumps, wherein the first heat pump transfer heat from the first liquid to the second liquid and increases the temperature thereof.

[0026] In a third stage of the heat transfer, the first liquid is transferred from the first heat pump to the return inlet as a return-liquid which may be used for cooling at the heat producer, and the second liquid is transferred to the second heat-outlet where it is utilised by the heat consumer.

[0027] The passive liquid-to-liquid heat exchanger in series with the series of heat pumps may save up to approximately 70% to 80% of electricity consumed compared to a single heat pump which transfers the same amount of heat from one liquid to another liquid.

[0028] One advantage of providing a series of heat pumps configured for transferring heat from the first liquid to the second liquid is that it ensures that the second liquid has a high enough temperature in order to be used by the heat consumer. Although the heat-and-cooling system requires energy in terms of electricity in order to provide heat to the second liquid, the energy consumed by the system is less compared to other heat generators such as e.g., boilers, water heater, electric heaters, etc. The energy efficiency of the heat-and-cooling system may be in the order of approximately eight on the scale of coefficient of power (COP), wherein the COP is the measured energy of the heating divided by the energy of the electricity consumed by the heat-and-cooling system. Compared to individual cooling and heating systems, which are respectively coupled to the heat producer and the heat consumer, respectively, the heat-and-cooling system may reduce energy consumption of cooling and heating by approximately 90%.

[0029] In one aspect, the one or more heat pumps in the series of heat pumps may comprise a valve unit and a recirculation unit configured for recirculating the first liquid from a downstream position relative to the heat pump to an upstream position relative to the heat pump, wherein the valve unit is configured to adjust the amount of recirculation. In a further aspect, a recirculation pump may be provided in the recirculation unit, so that flow of the recirculation may be adjusted. The recirculation unit may be provided as a liquid connection between the downstream position and the upstream position relative to the heat pump.

[0030] The recirculation may enable the heat pumps to transfer more heat from the first liquid to the second liquid. Hence, the recirculation of the first liquid is advantageous in scenarios where the heat production from the heat producer varies, i.e. the heat production is above the capacity of the one or more heat pumps, or the temperature provided to the second liquid is below the target temperature required by the heat consumer. In one aspect, a pump unit may be arranged downstream to each heat pump in the series of heat pumps, wherein the pump unit is configured to increase the flow of the liquid flowing out of the heat pump. In another aspect, a pump unit may also be arranged upstream to the passive liquid-to-liquid heat exchanger, so that the flow of the first liquid between the first heat-outlet of the heat producer and the first inlet of the heat exchanger is increased, and / or the flow of the second liquid between the consumer return and the second inlet of the heat exchanger is increased.

[0031] In a further embodiment of the heat-and-cooling system, the series of heat pumps comprises two or more heat pumps, wherein a second heat pump is downstream to the first heat pump relative to the flow of the first liquid and between the passive liquid-to-liquid heat exchanger and the first heat pump relative to the flow of the second liquid.

[0032] The series of heat pumps may comprise at least two or more heat pumps configured for transferring heat from the first liquid to the second liquid, wherein a first heat pump is downstream to the heat exchanger and upstream to a second heat pump relative to a flow of the first liquid and the second heat pump is downstream to the heat exchanger and upstream to the first heat pump relative to a flow of the second liquid, wherein the second heat pump transfers the first liquid to the return inlet and the first heat pump transfers the second liquid to the second heat-outlet.

[0033] The second stage of the heat transfer may be provided by the series of heat pumps, which is achieved by transferring the first liquid from the first outlet of the passive liquid-to-liquid heat exchanger downstream to the first heat pump in the series of heat pumps, wherein the first heat pump transfer heat from the first liquid to the second liquid and increases the temperature. Then, the first liquid is transferred to the second heat pump, wherein the remaining heat is transferred to the second liquid and the temperature thereof is increased by the second heat pump. When viewed on the side of the second liquid, the second liquid is transferred from the second outlet of the passive liquid-to-liquid heat exchanger downstream to the second heat pump, wherein heat is received from the first liquid by the second heat pump. Finally, the second liquid is transferred downstream to the first heat pump wherein heat from the first liquid is transferred to the second liquid by the first heat pump.

[0034] In a further aspect, the series of heat pumps may comprise three or more heat pumps, wherein the heat pumps are arranged in series in a similar manner to the two heat pumps. For heat producers with a small heat production capacity (e.g. below 200,000 Watts), a single heat pump in the series of heat pumps may be adequate and yields a high efficiency. However, as the heat production capacity is increased (e.g. above 1 ,000,000 Watts) further heat pumps may be required to be arranged in series to maintain an efficient transfer of the heat.

[0035] Based on current available heat pumps and for very larger heat production capacities, a single or even two heat pumps may have lower capacity than the heat producers and hence three or more heat pumps may be required to meet peak excess heat production.

[0036] Using two heat pumps in series is advantageous as it may save approximately 20% to 30% of the electricity consumed compared to a single heat pump. Hence, an advantage of providing at least two or more than two heat pumps in series is that the efficiency of the heat- and-cooling system is increased when the heat production capacity is very high. Another advantage is the serial connection of the heat pumps which is advantageous compared to e.g. arranging the heat pumps in parallel.

[0037] In a further embodiment of the heat-and-cooling system, the heat-producing section comprises a buffer-storage configured to store a medium configured for providing cooling to the heat producer.

[0038] In one aspect, the return liquid or a part of the return liquid may be transferred to the bufferstorage. The buffer-storage may store the return liquid, or it may transfer cooling energy of the return liquid to another medium. The medium of the buffer-storage may be a phasechanging material or a liquid composition, wherein the liquid composition may be a mixture of glycerol and one or more liquids. The cooling energy stored in the buffer-storage may be transferred to the heat producer when the heat producer requires a return liquid and / or cooling.

[0039] In one aspect, the buffer-storage may be capable of storing a large volume of liquid for cooling, e.g. in the range of 100 to 2000 cubic meters or more. The volume of the bufferstorage may be sized according to the capacity of the heat-and-cooling system and / or the heat producer.

[0040] One advantage of providing the buffer-storage is that all of or a part of the cooling energy in the return-liquid may be stored when the one or more heat producers do not require any cooling or only requires a smaller amount of cooling, wherein the stored cooling may be used at a later time. A further advantage is that the buffer-storage may be used to store additional cooling energy which may be produced in excess by the heat-and-cooling system when the price of electricity is low and / or when excess electricity needs to be consumed to balance electricity market demands, e.g. to balance the frequency of the electricity market.

[0041] A further advantage is that the heat-and-cooling system is capable of providing a return-liquid and / or cooling to the heat producer at any time, e.g., even during downtime of the heatconsuming section and / or the heat-transferring section. Hence, the heat-and-cooling system may be able to reliably transfer cooling to one or more data centers regardless of the excess heat being transferred to the heat consumer, wherein the data centers are the heat producers.

[0042] In a further embodiment of the heat-and-cooling system, the heat-consuming section comprises a heat buffer-storage configured to store a heated-medium, wherein the heat buffer-storage is configured to store heat by receiving the second liquid from the first heat pump and to provide the stored heat to the heat consumer.

[0043] In one aspect, the second liquid or a part of the second liquid may be transferred to the heat buffer-storage. The heat buffer-storage may store the second liquid or it may transfer heat energy of the second liquid to another heated-medium. The heated-medium of the heat buffer-storage may be a phase-changing material; solid materials; or a liquid composition. The heat energy stored in the heat buffer-storage may be transferred to the heat consumer when the heat consumer requires a heated liquid.

[0044] In one aspect, the heat buffer-storage may be capable of storing a large volume of liquid for storing heat, e.g. in the range of 100 to 2000 cubic meters or more. The volume of the heat buffer-storage may be sized according to the capacity of the heat-and-cooling system and / or the heat consumer.

[0045] One advantage of providing the heat buffer-storage is that all of or a part of the heat energy in the second liquid may be stored when the one or more heat consumers do not require any heat or only requires a smaller amount of heat, wherein the stored heat may be used at a later time.

[0046] A further advantage is that the heat buffer-storage may be used to store additional heat energy, which may be produced in excess by the heat-and-cooling system when the price of electricity is low and / or when excess electricity needs to be consumed to balance electricity market demands, e.g. to balance the frequency of the electricity market.

[0047] A further advantage is that the heat-and-cooling system is capable of providing the second liquid and / or heat to the heat consumer at any time, e.g., during downtime of the heatproducing section. Hence, the heat-and-cooling system may be able to reliably transfer heat to district heating regardless of the excess heat being produced by the heat producer.

[0048] In a further embodiment of the heat-and-cooling system, the system comprises a closed loop comprising a second passive liquid-to-liquid heat exchanger configured to provide cooling and heat to the first liquid and is connected to the first heat-outlet and the return inlet, wherein a third liquid circulates the closed loop and the closed loop comprises a generator unit configured to provide cooling and / or heat to the third liquid.

[0049] In one aspect, the third liquid may be water, glycerol, or a liquid composition of two or more liquids such as e.g., water and glycol. In one aspect, glycerol may be ethylene glycol or propylene glycol. One advantage of using pure glycerol or a composition comprising part glycerol is that it has a substantially lower freezing point temperature than water.

[0050] In one aspect, the generator unit may comprise a cooling tower, a fan unit, an air-source heat pump, an air-to-liquid heat pump, a dry cooler, and / or an air-to-liquid heat pump.

[0051] Generally, the generator unit may be in a heating mode and a cooling mode. In the heating mode, heat energy may be extracted from outside air and transferred into the third liquid by circulating the third liquid in the closed loop. When the third liquid is heated, the heat may be transferred to the first liquid through the second passive liquid-to-liquid heat exchanger and then further downstream to the heat-transferring section. In the cooling mode, circulation of the third liquid is reversed relative to the heating mode and heat (even if at an ambient or near-ambient temperature) is transferred from the first liquid through the second passive liquid-to-liquid heat exchanger to the third liquid, while cooling is transferred back to the first liquid. One advantage of the generator unit is that it may provide at least two to four times more heat or cooling energy compared to the electrical energy consumed by the generator unit, i.e. a COP of four.

[0052] One advantage of using the generator unit is that transfer of heat to the heat consumer and transfer of cooling to the heat producer becomes fully independent of the corresponding heat producer and heat consumer. Le., the heat-and-cooling system is fully capable of providing heat without a heat producer and is also fully capable of providing cooling without a heat consumer and / or the heat-transferring section. Hence, the heat-and-cooling system meets the flexibility requirements of both the heat consumer (e.g., district heating) and the heat producer (e.g., a data center).

[0053] A further advantage is achieved when the closed loop and generator unit is combined with the buffer-storage and / or the heat buffer-storage, as the heat-and-cooling system becomes capable of producing excess cooling and / or heat which are stored in the respective bufferstorages e.g. when the price of electricity is low and / or when excess electricity needs to be consumed to balance electricity market demands. Thus, these advantages are further advantageous as the flexibility provided may also be beneficial in-terms of cost savings during low electricity prices and / or in terms of being able to balance the electricity market.

[0054] In a further embodiment of the heat-and-cooling system, the system comprises one or more temperature sensors configured to measure a temperature of the first liquid and the second liquid and a controller configured to adjust the operation of the one or more heat pumps as a function of a temperature of the second liquid transferred to the second heat-outlet.

[0055] The temperature sensors may be arranged downstream and / or upstream to the one or more heat pumps.

[0056] In one aspect, the controller may be implemented on a general processing unit, a computer, a microprocessor, a programmable system on chip, or any other suitable processing unit.

[0057] In another aspect, one or more flow sensors may also be arranged downstream and / or upstream to the one or more heat pumps, wherein the flow sensors are configured to measure the flow of the first liquid and / or the second liquid. In a further aspect, the heatproducing section, the heat-consuming section, the heat-transferring section and / or the closed loop may comprise one or more pumps configured to increase and / or decrease the flow of the first liquid, the second liquid and / or the third liquid. The one or more pumps may be controlled as a function of the measured temperatures and / or flow measurements.

[0058] In one aspect, the heat-producing section, the heat-consuming section, the heat-transferring section and / or the closed loop may comprise one or more valves configured to adjust the flow of the first liquid, second liquid and / or third liquid, wherein the valves are controlled by the controller. The controller may use the one or more temperature measurements and / or flow measurements to determine the one or more valve adjustments. In a further embodiment the heat-and-cooling system, the temperature of the second liquid transferred to the second heat-outlet is in the range of 50 to 90 degrees Celsius, or 65 to 85 degrees Celsius, or 70 to 80 degrees Celsius.

[0059] One advantage of ensuring that the temperature of the second liquid transferred to the second heat-outlet is at least 50 degrees and preferably more, is that the second liquid is suitable for being used by the heat consumer, e.g. as heating in district heating.

[0060] In a further embodiment of the heat-and-cooling system, the controller is configured to adjust the operation of the one or more heat pumps as a function of a temperature of the returnliquid returned to the return inlet.

[0061] One advantage of controlling the operation of the one or more heat pumps as a function of the temperature of the return-liquid is that the efficiency of the heat-transferring section may be improved. In one scenario the heat producer may not require a return-liquid with a temperature below ambient temperature, and hence energy may be saved as the returnliquid may be transferred to the heat producer at the required temperature. This is advantageous in a scenario wherein the heat producer is able to produce excess heat to the first liquid flowing out of the heat producer by receiving a warmer return-liquid from the heattransferring section without the warmer return-liquid being detrimental to the heat producer. Such a scenario may e.g., be a heat extraction system coupled to a data center, wherein providing a warmer liquid to a plurality of liquid coolers of the heat extraction system can adequately cool the server hardware.

[0062] In a further embodiment of the heat-and-cooling system, the temperature of the return-liquid returned to the return inlet is in the range of 5 to 45 degrees Celsius, 8-40 degrees Celsius, 30-45 degrees Celsius, or 19 to 23 degrees Celsius, or 20 to 22 degrees Celsius.

[0063] One advantage of providing a low temperature of the return-liquid, e.g. between 5 and 15 degrees Celsius, is that the cooling process of the heat producer may be improved due to the low temperature of the return-liquid.

[0064] Another advantage of the low temperature of the return-liquid is that when the return-liquid may be stored in the buffer-storage, the return-liquid may be stored for a longer period of time before the cooling energy dissipates, thus prolonging the period in which the bufferstorage may be able to provide cooling. One advantage of providing a higher temperature of the return-liquid, e.g. between 30 and 45 degrees Celsius is that the return-liquid is advantageous for a heat producer able to produce warmer excess heat to the first liquid flowing out of the heat producer by receiving a higher temperature return-liquid without the higher temperature return-liquid being detrimental to the heat producer. Such a scenario may be when the heat producer is e.g., a heat extraction system coupled to a data center, wherein providing a higher temperature liquid to a plurality of liquid coolers can adequately cool the server hardware.

[0065] A further objective of the invention is achieved by a method of transferring heat from a heat producer to a heat consumer and for transferring cooling to the heat producer, wherein the method comprises steps of:

[0066] - providing a first liquid configured to conduct heat from the heat producer;

[0067] - transferring heat from the first liquid to a second liquid through a passive liquid-to-liquid heat exchanger, wherein the second liquid is transferred to the heat exchanger from the heat consumer;

[0068] - circulating the first and second liquid from the liquid-to-liquid heat exchanger to a series of heat pumps comprising at least one or more heat pumps; and

[0069] - transferring heat from the first liquid to the second liquid through the series of heat pumps, wherein the second liquid is transferred to a heat consumer and the first liquid is returned to the heat producer.

[0070] In one aspect the first liquid may be transferred from the series of heat pumps to the heat producer after heat from the first liquid has been transferred to the second liquid, so that the first liquid may be heated again by the heat producer.

[0071] In a further embodiment of the method, the method comprises further steps of:

[0072] - storing cooling of the first liquid in a buffer-storage; and

[0073] - transferring cooling from the buffer-storage to the first liquid and transferring the first liquid to the heat producer.

[0074] In one aspect, the first liquid may be the return-liquid as described in the present disclosure.

[0075] The cooling from the first liquid may be transferred from the series of heat pumps or it may be transferred from a second passive liquid-to-liquid heat exchanger to the first liquid and then to the buffer-storage.

[0076] In a further embodiment of the method, the method comprises further steps of:

[0077] - storing thermal energy of the second liquid in a heat buffer-storage; and - transferring thermal energy from the heat buffer-storage to the second liquid and transferring the second liquid to the heat consumer.

[0078] In a further embodiment of the method, the method comprises a further step of providing cooling and / or heat to the first liquid by circulating the first liquid to a second liquid-to-liquid heat exchanger connected to closed loop comprising a generator unit configured to provide cooling and / or heat to a third liquid in the closed loop.

[0079] In one aspect, the closed loop may be thermally coupled to the first liquid through the second passive liquid-to-liquid heat exchanger configured to transfer cooling and / or heat between the third liquid and the second liquid.

[0080] The cooling and / or heat may be transferred to the first liquid from the third liquid through the second passive liquid-to-liquid heat exchanger.

[0081] The heat and / or cooling generated in the closed loop by the generator unit may be used to provide cooling to the heat producer and / or heat to the second liquid through the steps of the method of transferring heat from the heat producer to the heat consumer. This is advantageous as it ensures that the heat producer may receive cooling at any time regardless of whether the heat consumer receives any heat. Furthermore, it is also advantageous in that the heat consumer can receive heat regardless of whether the heat producer provides any heat.

[0082] One objective of the invention is achieved by providing a heat producer suitable for being used in the heat-and-cooling system, wherein the heat producer may be a liquid cooling system for extracting heat from a server arranged in a rack, wherein the liquid cooling system comprises:

[0083] - a circuit comprising a plurality of channels configured to guide a flow of liquid;

[0084] - a first air-to-liquid heat exchanger arranged on a first circuit and configured to absorb heat from air within a cabinet housing the server by circulating the liquid through the first air-to- liquid heat exchanger; and

[0085] - a liquid cold-plate arranged on a second circuit and in thermal communication with a heatintensity device of the server and configured for absorbing heat from the heat-intensity device, wherein the first circuit is serially connected by a liquid channel to the second circuit, wherein the liquid cold-plate is downstream to the air-to-liquid heat exchanger relative to the liquid flow. The rack may comprise a plurality of servers, wherein each server may function as a database server, a web server, media-processing server, a computing server, a game server, email server, proxy server, scientific server, file server. Generally, a server may be contained in a single cabinet. However, a server may also require several cabinets, i.e., a distributed server. Furthermore, a single server cabinet may also house a plurality of server functions, e.g., by being configured to perform server virtualization.

[0086] Each server may comprise one or more heat-intensity devices such as a general processing unit (CPU), a graphics processing unit (GPU), field-programmable gate array (FPGA), neural processing unit (NPU), deep learning processor, accelerated processing unit (APU), chipset, data storage media such as random-access memory (RAM) or solid-state drives (SSD), and network and communication processors, among others.

[0087] The circuit comprising a plurality of channels configured to guide a flow of liquid may comprise a circuit loop, wherein the circuit comprises a heat outlet configured for extracting a heated liquid from the circuit and a cooling inlet configured for transferring a cooled liquid to the circuit. In one aspect, a cooling unit may be connected to the cooling inlet and be configured to extract heat from and cool the liquid flowing through the circuit. The cooling unit may be a liquid-to-liquid heat exchanger configured for extracting heating from the liquid and transfer the heating to an output liquid.

[0088] In one aspect, the liquid cooling system may comprise a single air-to-liquid heat exchanger configured to absorb heating from the air within the one or more cabinets housing the servers. In this aspect, the heat exchanger may cover an entire side of the rack. In a further aspect, an air-to-liquid heat exchanger may be arranged in contact or the vicinity of each cabinet housing a server. In this aspect where multiple servers are arranged in a rack each comprising an air-to-liquid heat exchanger, the liquid flowing through each air-to-liquid heat exchangers may be configured to flow in parallel from a downstream to an upstream position of the first circuit.

[0089] In one aspect, the second circuit may comprise one or more manifolds configured to distribute the flow of liquid to two or more liquid cold-plates in thermal communication with heat-intensity devices. Le., the liquid cold-plates may be arranged in parallel relative to the flow of liquid. Preferably, a plurality of liquid cold-plates is connected to the manifold in order to provide cooling to a plurality of heat-intensity devices in a plurality of servers. In a further aspect, if a server in a cabinet comprises two, three or more heat-intensity devices e.g., two CPUs or two CPUs and a GPU or any other combination thereof, the liquid cold-plates may be serially connected so that only one inlet channel and one outlet channel must be provided to provide a flow of liquid into and out of the cabinet.

[0090] The liquid cold-plate may be a piece of metal configured for being coupled with a heat dissipating surface of the heat-intensity devices and configured to absorb heat from the heatintensity devices. The liquid cold-plate may comprise internal channels and chambers comprising heat sinks configured to efficiently transfer heat to the liquid. In another aspect, the liquid cold-plate may comprise heat pipes configured to transfer the heat efficiently to the liquid.

[0091] One advantage of providing a manifold is that heat may be extracted from a plurality of heatintensity devices at once, and hence the liquid cooling system can provide cooling and heat extraction from a plurality of servers in a rack. A further advantage is that the rack can be built and upgraded in an easy and modular manner simply by plugging further channels into the manifold, so that further liquid cold-plates are connected to the second circuit.

[0092] One advantage of serially connecting the first circuit by a liquid channel to the second circuit, is that the liquid first absorbs heating from the air by being circulated through the first air-to- liquid heat exchanger and then secondly absorbs heating from the liquid cold-plates by being circulated through the second circuit and flowing over the one or more liquid cold-plates, thus obtaining a higher output temperature compared to if the first and second circuit were arranged in parallel or not connected altogether, wherein the output temperature is measured downstream to the second circuit.

[0093] In one example, the first air-to-liquid heat exchanger may be supplied with a liquid at a low initial temperature (e.g., an ambient temperature of 18 to 25 degrees Celsius) and the first air-to-liquid heat exchanger may raise an intermediate temperature of the liquid to a medium level (e.g., 30-35 degrees Celsius) and then further heat absorption at the liquid cold-plates further raises the liquid temperature to a scalding level (e.g., 50-90 degrees Celsius), wherein the initial temperature and intermediate temperature are measured upstream and downstream to the first air-to-liquid heat exchanger, respectively. If the second circuit and consequently the liquid cold-plates were provided with a liquid with a lower input temperature (e.g., 15-25 degrees Celsius) measured upstream to the liquid cold-plates, the output temperature would not consistently reach a scalding or a high level of heating and thus the liquid is not heated sufficiently in order to be re-used as waste heat.

[0094] Hence, an advantage of the liquid cooling system is that the high level of heating being extracted from the server and transferred into the liquid may be used as waste heat for heat demanding processes. The waste heat may be re-used either by transferring the heated liquid to the heat demanding process or by converting the heat stored in the heated liquid to another liquid or another medium such as a gas. Among others, the heat demanding processes may be for heat consumers in district heating, greenhouses, space heating, industrial manufacturing, etc.

[0095] A further advantage of heat extraction from both the air within the cabinets housing the servers and the heat-intensity devices is that the server hardware is cooled so that the server hardware achieves a long lifespan, can operate continuously with minimal downtime, and avoids thermal throttling which reduces performance.

[0096] In a further embodiment of the liquid cooling system, the first circuit comprises a first recirculation channel arranged between an upstream and a downstream position relative to the first air-to-liquid heat exchanger and wherein the first circuit comprises a first valve unit configured to adjust recirculation of the liquid through the first circuit.

[0097] The first valve unit may be configured to adjust the flow of liquid through one or more channels, e.g., a T-shaped joint, wherein the first recirculation channel may form a part of the T-shaped joint. In one aspect, the first valve unit may be a three-way valve. In a further aspect, the first valve unit may be two separate one-way valves arranged on two channels of a T-shaped joint, e.g., the first recirculation channel and a channel upstream to the first air- to-liquid heat exchanger.

[0098] One advantage of providing a gradual liquid recirculation to the flow of liquid through the first circuit is that the recirculated liquid decreases occurrence of cold and / or hot spots / pockets trapped within channels of the first circuit and / or the first air-to-liquid heat exchanger.

[0099] One advantage of providing a greater degree of recirculation of the flow of liquid through the first circuit and the first air-to-liquid heat exchanger is that the intermediate temperature of the liquid measured downstream to the first air-to-liquid heat exchanger may reach an even higher temperature. Thus, if the air within the cabinet housing the servers is at a low temperature, the recirculation may ensure that the intermediate temperature is still high, so that the liquid which is transferred into the second circuit and out of the second circuit is at a high output temperature, so that it may be re-used as waste heat.

[0100] A further advantage of the first valve unit is that it enables the liquid to gradually or completely bypass the first air-to-liquid heat exchanger. In one scenario, the bypass may be favorable if the air within the cabinet does not require cooling; if the intermediate temperature of the liquid downstream to the first air-to-liquid heat exchanger is sufficiently high; and / or if the one or more heat-intensity devices require a higher-than-normal amount of cooling from the liquid cold-plates to e.g., protect the heat-intensity devices from damage due to overheating or prevent thermal throttling.

[0101] In a further embodiment of the liquid cooling system, the second circuit comprises a second recirculation channel arranged between an upstream and a downstream position relative to the liquid cold-plate and wherein the second circuit comprises a second valve unit configured to adjust recirculation of the liquid through the second circuit.

[0102] The second valve unit may be configured to adjust the flow of liquid through one or more channels, e.g., a T-shaped joint, wherein the second recirculation channel may form a part of the T-shaped joint. In one aspect, the second valve unit may be a three-way valve. In a further aspect, the second valve unit may be two separate one-way valves arranged on two channels of a T-shaped joint, e.g., the second recirculation channel and a channel upstream to the liquid cold-plate.

[0103] One advantage of providing a gradual liquid recirculation to the flow of liquid through the second circuit is that the recirculated liquid decreases occurrence of cold and / or hot spots / pockets trapped within channels of the second circuit and / or the one or more liquid cold-plates.

[0104] One advantage of providing a greater degree of recirculation of the flow of liquid through the second circuit and the one or more liquid cold-plates is that the output temperature of the liquid measured downstream to the liquid cold-plates may reach an even higher temperature. Thus, if the one or more heat-intensity devices are running at a lower temperature, the recirculation may ensure that the output temperature is still high so that the heated liquid or the heat which is extracted from the liquid cooling system may be re-used as waste heat.

[0105] A further advantage of the second valve unit is that it enables the liquid to gradually or completely bypass the one or more liquid cold-plates. In one example, the bypass may be favorable if the one or more heat-intensity devices do not require cooling.

[0106] In a further embodiment of the liquid cooling system, the first circuit and / or the second circuit comprises one or more pumps configured to adjust and / or maintain the flow of liquid through the circuit. In one aspect, the one or more pumps may be arranged upstream to the first air-to-liquid heat exchanger and / or upstream to the one or more liquid cold-plates.

[0107] In one aspect, one or more pressure sensors may be arranged upstream and / or downstream to each pump, wherein the pressure sensors are configured to measure the pressure of the liquid and wherein the pressure of the liquid may be used to control a pumping speed of the one or more pumps. In a further aspect, pressure sensors arranged upstream and downstream to a pump may be used to determine a differential pressure, wherein the differential pressure may be used to control the pump.

[0108] One advantage of increasing the flow of liquid through the first circuit and / or the second circuit is that the heat absorption in the first air-to-liquid heat exchanger and / or the one or more liquid cold-plates is decreased for a given volume of liquid, respectively. Consequently, one advantage of decreasing the flow of liquid through the first circuit and / or the second circuit is that the heat absorption in the first air-to-liquid heat exchanger and / or the one or more liquid cold-plates is increased for a given volume of liquid, respectively.

[0109] A further advantage of increasing the flow of liquid is that the occurrence of cold and / or hot spots / pockets trapped within channels of the first and second circuits, the first air-to-liquid heat exchanger, and the one or more liquid cold-plates may be reduced.

[0110] In a further embodiment of the liquid cooling system, the system comprises one or more temperature sensors configured for measuring a temperature of the liquid, one or more flow sensors configured for measuring a flow of the liquid, and a controller configured to adjust the first and / or second valve units and / or the one or more pumps, so that an output temperature of the liquid downstream to the liquid cold-plate is maximised while the heatintensity device is sufficiently cooled.

[0111] In one aspect, the temperature sensors and / or the flow sensors may be arranged upstream and / or downstream to the one or more liquid cold-plates and / or the first air-to-liquid heat exchanger. Thus, the temperature sensors provide a measurement of the output temperature, measured downstream to the liquid cold plates; an intermediate temperature, measured downstream to the first air-to-liquid heat exchanger or upstream to the liquid coldplates; or an initial temperature, measured upstream to the first air-to-liquid heat exchanger. Similarly, the flow sensors provide a measurement of the flow of the liquid at various positions along the circuit, the first circuit, and / or the second circuit. The one or more flow sensors may be used to adjust the speed of the one or more pumps to achieve an accurate control of the flow of liquid and in turn an optimal cooling of the server and / or optimal heat extraction.

[0112] In a further aspect, an air temperature sensor may be arranged inside the one or more cabinets housing the servers, wherein the air temperature sensor is configured to measure an air temperature. The cooling capacity of the first air-to-liquid heat exchanger may be controlled as a function of the air temperature, by e.g., increasing or decreasing the flow of liquid through the first air-to-liquid heat exchanger and / or increasing an airflow through the cabinet.

[0113] In one aspect, the controller may be implemented on a general processing unit, a computer, a microprocessor, a programmable system on a chip, or any other suitable processing unit.

[0114] The controller may implement a control loop to adjust the valve units and / or the one or more pumps based on a proportional, integral and / or derivative control algorithm or a combination thereof, e.g. a proportional-integral control algorithm or a proportional-integra-derivative control algorithm.

[0115] One advantage of providing a controller and adjusting the one or more valve units and / or the one or more pumps is that the intermediate temperature and / or the output temperature may be very precisely controlled, hence ensuring that the air within the cabinet and / or the heatintensity devices are sufficiently cooled while an optimal amount of heat is extracted from the air and the heat-intensity devices. Thus, by being able to extract a great amount of heat from the servers, the heat can be re-used e.g., to deliver heating for an industrial plant, warm water supply, and / or district heating.

[0116] In one scenario, where one or more servers are not running at full capacity, the pumps may be adjusted to provide a lower flow of liquid so that the intermediate temperature and / or output temperature are still at a high level required in order to use the heated liquid as waste heat.

[0117] In a further embodiment of the liquid cooling system, the output temperature is in the range of 50 to 90 degrees Celsius, or 60 to 80 degrees Celsius, or 65 to 75 degrees Celsius.

[0118] One advantage of ensuring that the output temperature of the liquid is at least 50 degrees Celsius is that the liquid is warm enough to be re-used in an efficient manner. More preferably, if the output temperature is at least 60 degrees Celsius and up to 90 degrees Celsius, the re-use of the heated liquid may be very efficient and the re-use entails that the energy consumed on the heat extraction from the servers, essentially the server cooling, is more environmentally friendly because the extracted heat is not rejected into the atmosphere as waste heat.

[0119] In a further embodiment of the liquid cooling system, a second air-to-liquid heat exchanger is arranged on a circuit in parallel with the first air-to-liquid heat exchanger and is configured to cool a second rack.

[0120] In one aspect, the second air-to-liquid heat exchanger may be an in-row cooler arranged between two server racks and configured to absorb heating from the two adjacent racks.

[0121] The second air-to-liquid heat exchanger may be arranged in parallel to the first circuit or the first air-to-liquid heat exchanger by a cold liquid input and a warm liquid output of the second air-to-liquid heat exchanger being connected to an upstream position and a downstream position of the first circuit or the first air-to-liquid heat exchanger. In one aspect, the warm liquid output of the air-to-liquid heat exchanger may be connected to the one or more liquid cold-plates and / or it may be connected to the output liquid or the heat outlet, wherein this connection may be controlled by a valve unit, e.g., a three-way valve.

[0122] One advantage of arranging the first and second air-to-liquid heat exchangers in parallel is that an intermediate temperature of the liquid measured downstream to the two or more air- to-liquid heat exchangers is at a higher temperature compared to a single air-to-liquid heat exchanger.

[0123] In a further embodiment of the liquid cooling system, the first and / or second air-to-liquid heat exchanger is a rear-door cooler or computer room air-conditioning or in-row cooler or in-rack cooler or an aisle containment system, wherein the first and / or second air-to-liquid heat exchangers are configured to absorb heating from a plurality of servers arranged in a rack.

[0124] A further objective of the invention is achieved by a method for extracting heat from a rack with a server, wherein the method comprises the steps of:

[0125] - providing a rack with a server, the rack comprising an air-to-liquid heat exchanger and the server comprising a heat-intensity device with a liquid cold-plate;

[0126] - generating a liquid flow from the air-to-liquid heat exchanger through the liquid cold-plate; and

[0127] - adjusting the liquid flow to have a liquid temperature exiting the liquid cold-plate above 50 degrees Celsius. The method for extracting heat from a rack with a server may be in relation to the liquid cooling system and hence also the heat producer suitable for being used in the heat-and- cooling system and the related method of transferring heat from a heat producer to a heat consumer and for transferring cooling to the heat producer.

[0128] The air-to-liquid heat exchanger may be configured to absorb heat from air within the rack and transfer the heat into a liquid. The liquid cold-plate may be configured to absorb heat from the heat-intensity device and transfer the heat into a liquid.

[0129] One advantage of generating the liquid flow from the air-to-liquid heat exchanger through the liquid cold-plate is that the temperature of the liquid exiting the liquid cold-plate is higher compared to if the air-to-liquid heat exchanger is arranged parallel to the liquid cold-plate or if the liquid does not flow through the air-to-liquid heat exchanger before flowing through the liquid cold-plate.

[0130] A further advantage of extracting heat from a server and the heat-intensity devices is that the server and the heat-intensity devices are cooled and thus may yield a higher computational performance, or a longer lifespan of the computer components may entail.

[0131] In one aspect, the liquid flow may be adjusted by decreasing or increasing the flowrate of the liquid flow so that a volume of the liquid absorbs heat over a longer or shorter period of time, respectively.

[0132] One advantage of adjusting the liquid flow to obtain a liquid temperature above 50 degrees Celsius is that heat energy in the liquid may be re-used for a variety of heating purposes, e.g., district heating or for industrial applications. Hence, an environmental impact of the heat extraction is lessened.

[0133] In a further embodiment of the method, the method comprises a further step of:

[0134] - recirculating part of the liquid through the air-to-liquid heat exchanger and / or the liquid coldplate.

[0135] Recirculation of a part of the liquid through the air-to-liquid heat exchanger and / or the liquid cold-plate may be achieved by providing at least one valve unit configured to recirculate a part of the liquid from a downstream position to an upstream position relative to the air-to- liquid heat exchanger and / or the liquid cold-plate, respectively. One advantage of providing recirculation of a part of the liquid through the air-to-liquid heat exchanger and / or the liquid cold-plate is that the recirculated liquid decreases occurrence of cold and / or hot spots / pockets trapped in the air-to-liquid heat exchanger and / or the liquid cold-plate.

[0136] One further advantage of providing the recirculation of the liquid flow through the air-to-liquid heat exchanger and / or the liquid cold-plate is that the liquid temperature exiting the liquid cold-plate may reach an even higher temperature. Thus, if the one or more heat-intensity devices are running at a lower temperature, the recirculation may ensure that the liquid temperature is still high so that the liquid may be re-used as waste heat.

[0137] A further advantage of the recirculation of the liquid is that the recirculation may enable the flow of the liquid to be at a higher flow, while still ensuring that as much heat as possible is absorbed from the air within the rack and / or from the heat-intensity device.

[0138] In a further embodiment of the method, the method comprises a further step of:

[0139] - utilising the liquid flow with the liquid temperature above 50 degrees Celsius for heating such as for heat consumers in district heating or industrial greenhouses or swimming pools or office installation or other industrial applications.

[0140] One advantage of utilising the heated liquid flow for heating is that an environmental impact of the heat extraction is lessened, and hence also the energy consumed on cooling the servers is lessened.

[0141] Description of the Drawing

[0142] Various examples are described hereinafter with reference to the figures. The reference numerals refer to the elements throughout. The elements will, thus, not be described in detail with respect to the description of each figure. It should also be noted that the figures are only intended to facilitate the description of the examples. They are not intended as an exhaustive description of the claimed invention or as a limitation on the scope of the claimed invention. In addition, an illustrated example need not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular example is not necessarily limited to that example and can be practiced in any other examples even if not so illustrated, or if not so explicitly described.

[0143] Exemplary embodiments of the invention are described in the figures, whereon:

[0144] Fig. 1a illustrates one embodiment of a heat-and-cooling system. Fig. 1b illustrates one embodiment of a heat-and-cooling system.

[0145] Fig. 2a illustrates one embodiment of a heat-and-cooling system.

[0146] Fig. 2b illustrates one embodiment of a heat-and-cooling system.

[0147] Fig. 3a illustrates one embodiment of a method of transferring heat from a heat producer to a heat consumer.

[0148] Fig. 3b illustrates one embodiment of a method of transferring heat from a heat producer to a heat consumer.

[0149] Fig. 4a illustrates one embodiment of a rack.

[0150] Fig. 4b illustrates one embodiment of a liquid-cooler unit.

[0151] Fig. 5a illustrates one embodiment of a liquid cooling system.

[0152] Fig. 5b illustrates one further embodiment of a liquid cooling system.

[0153] Fig. 5c illustrates one further embodiment of a liquid cooling system.

[0154] Fig. 5d illustrates one further embodiment of a liquid cooling system.

[0155] Fig. 6a illustrates one embodiment of a method for extracting heat.

[0156] Fig. 6b illustrates one further embodiment of a method for extracting heat.

[0157] Detailed Description of the Invention

[0158] Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings. In this regard, the present examples may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the examples are merely described below, by referring to the figures, to explain aspects.

[0159] Throughout the specification, when an element is referred to as being “connected” to another element, the element is “directly connected” to the other element, “electrically connected”, “f luidically connected”, or “communicatively connected” to the other element with one or more intervening elements interposed there between.

[0160] The terminology used herein is for the purpose of describing particular examples only and is not intended to be limiting. As used herein, the terms “comprises", "comprising", "includes", and / or "including" when used in this specification specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0161] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which this invention pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealised or overly formal sense unless expressly so defined in the present specification.

[0162]

[0163] Figure 1 a illustrates one embodiment of a heat-and-cooling system 1 for transferring heat from a heat producer 11 to a heat consumer 21 and for transferring cooling to the heat producer 11. The heat-and-cooling system 1 comprises three sections: a heat-producing section 10, a heat-consuming section 20, and a heat-transferring section 30 arranged between the heat-producing section 10 and the heat-consuming section 20.

[0164] The heat-producing section 10 comprises one or more heat producers 11 configured to provide a first liquid 16 at a first heat-outlet 12 and receive a return-liquid at a return inlet 13. The heat producer 11 may also be configured to provide heat to the first liquid 16 circulating through the heat producer 11. The return-liquid may be a cooled liquid or a liquid at an ambient temperature or a temperature above ambient.

[0165] The heat-consuming section 20 comprises a consumer return 23 and a second heat-outlet 22, wherein the second heat-outlet 22 is configured for transferring a second liquid 26 to one or more heat consumers 21 and the consumer return 23 is configured for receiving a returnliquid from the heat consumer 21 . The second liquid 26 is the liquid which receives heat from the first liquid through the heat-transferring section 30. The return-liquid is a liquid returned from the heat consumer 21 which may be re-heated again before being transferred back to the heat consumer. The heat-transferring section 30 comprises a passive liquid-to-liquid heat exchanger 40 configured to transfer heat from the first liquid to the second liquid. The passive liquid-to- liquid heat exchanger 40 comprises a first inlet 41 configured to receive the first liquid 16 from the first heat-outlet 12 and the heat exchanger 40 comprises a first outlet 42 configured to transfer the first liquid 16 downstream and away from the heat exchanger 40. After the first outlet 42, the first liquid 16 is transferred downstream to a first heat pump 50. On an adjacent side of the passive liquid-to-liquid heat exchanger 40, the heat exchanger 40 comprises a second inlet 43 configured to receive the return-liquid from the consumer-return 23 and the heat exchanger 40 comprises a second outlet 44 configured to transfer the second liquid 26 downstream to the first heat pump 50.

[0166] Figure 1 b illustrates one further embodiment of the heat-and-cooling system 1 , wherein the embodiment comprises the same aspects as in fig. 1 a. In this embodiment, the heatproducing section 10 comprises a buffer-storage 14 and the heat-consuming section 20 comprises a heat-buffer storage 24.

[0167] The buffer-storage 14 is configured to store a medium 15 configured to store cooling and provide cooling to the heat producer 11. The buffer-storage 14 may have such a large capacity that it can provide cooling to the heat producer 11 in the absence of return-liquid from the heat-transferring section 30. Furthermore, the buffer-storage 14 may be used to store excess cooling, e.g. when the heat producer 11 does not require cooling.

[0168] The heat buffer-storage 24 is configured to store a heated-medium 25 configured to store heat and provide heat to the heat consumer 21 . The heat buffer-storage 24 may have such a large capacity that it can store substantially all of the heat transferred to the second liquid 26 in scenarios where e.g. the heat producer 21 does not require any heated liquid or when excess heat is produced and transferred to the second liquid 26 by the heat-and-cooling system 1 during periods with low electricity prices.

[0169] Figure 2a illustrates one embodiment of the heat-and-cooling system 1 similar to the illustrations in fig. 1 b. This embodiment differs in how the heat-transferring section 30 is provided. This difference of the illustrated embodiment may also be applied to the embodiment illustrated in fig. 1a, wherein the heat-and-cooling system 1 does not comprise the buffer-storage 14 and the heat buffer-storage 24.

[0170] The heat-transferring section 30 is provided with a series of heat pumps comprising a first heat pump 50 and a second heat pump 60 arranged downstream to the first heat pump 50 relative to the flow of the first liquid 16 and upstream to the first heat pump 50 relative to the flow of the second liquid 26. Le. the first heat pump 50 and second heat pump 60 are serially connected, in another aspect further heat pumps may be provided in the same way to further increase the heat-transferring capacity.

[0171] The first heat pump 50 receives the first liquid 16 from the first outlet 42 of the passive liquid- to-liquid heat exchanger 40, and as heat form the first liquid 16 is transferred to the second liquid 26 through the first heat pump 50 the first liquid 16 flows to the second heat pump 60 wherein remaining heat is transferred to the second liquid 26. Downstream to the second heat pump 60, the first liquid flows as the return-liquid to the heat producer 11 and / or the buffer-storage 14.

[0172] The second heat pump 60 receives the second liquid 26 from the second outlet 44 of the passive liquid-to-liquid heat exchanger 40, and as heat from the first liquid 16 is transferred to the second liquid 26 through the second heat pump 60, the second liquid 26 flows downstream to the first heat pump 50, wherein heat is transferred to the second liquid 26 thereby increasing the total heat accumulation of the second liquid 26. Downstream from the first heat pump 50, the second liquid flows to the heat consumer 21 and / or the heat bufferstorage 24.

[0173] Figure 2b illustrates one embodiment of the heat-and-cooling system 1 similar to the embodiment illustrated in fig. 2a, wherein the heat-producing section 10 comprises a second passive liquid-to-liquid heat exchanger 70 configured to provide cooling and / or heat to the first liquid 16. The second passive liquid-to-liquid heat exchanger 70 is connected to the first heat-outlet 12 and the return inlet 13 and comprises a closed loop 71 wherein a third liquid circulates the closed loop 71. The closed loop 71 further comprises a generator unit 72 configured to provide cooling and / or heat to the third liquid, so that the cooling and / or heat may be transferred from the third liquid to the first liquid 16 through the second passive liquid-to-liquid heat exchanger 70. The heat and / or cooling provided by the generator unit 72 in the closed loop 71 is advantageous as it enables the heat-producing section 10 to produce heat in the absence of heat production from the heat producer 11 or in scenarios where the electricity price is low. Furthermore, the production of cooling is advantageous in scenarios where the heat-transferring section 30 is unable to produce a return-liquid to the heat producer 11 and / or the electricity prices are low and the cooling produced may be stored in the buffer-storage 14.

[0174] The second passive liquid-to-liquid heat exchanger 70, the closed loop 71 and generator unit 72 may also be adapted to the embodiment of the heat-and-cooling system 1 illustrated in fig. 1a and 1b. Figure 3a illustrates one embodiment of a method 100 of transferring heat from a heat producer to a heat consumer and for transferring cooling to the heat producer, wherein the method comprises steps of:

[0175] - providing 110 a first liquid configured to conduct heat from the heat producer;

[0176] - transferring 120 heat from the first liquid to a second liquid through a passive liquid-to-liquid heat exchanger, wherein the second liquid is transferred to the heat exchanger from the heat consumer;

[0177] - circulating 130 the first and second liquid from the liquid-to-liquid heat exchanger to a series of heat pumps comprising at least two or more heat pumps; and

[0178] - transferring 140 heat from the first liquid to the second liquid through the series of heat pumps, wherein the second liquid is transferred to a heat consumer and the first liquid is returned to the heat producer.

[0179] Figure 3b illustrates further embodiments of the method 100, wherein the method comprises further steps of:

[0180] - storing 150 cooling of the first liquid in a buffer-storage; and

[0181] - transferring 160 cooling from the buffer-storage to the first liquid and transferring the first liquid to the heat producer.

[0182] And wherein a further embodiment of the method comprises further steps of:

[0183] - storing 155 thermal energy of the second liquid in a heat buffer-storage; and

[0184] - transferring 165 thermal energy from the heat buffer-storage to the second liquid and transferring the second liquid to the heat consumer.

[0185] And wherein a further embodiment of the method comprises a further step of providing 170 cooling and / or heat to the first liquid by circulating the first liquid to a second liquid-to-liquid heat exchanger connected to closed loop comprising a generator unit configured to provide cooling and / or heat to a third liquid in the closed loop.

[0186] Figure 4a illustrates one embodiment of a rack 1010 comprising a plurality of servers 1011 housed in individual cabinets 1014 in the rack 1010. The air 1013 within the cabinets 1014 may be moved out of the cabinets 1014 by fans 1015 arranged in the cabinets 1014. In another aspect, the one or more fans 1015 may be arranged inside the one or more cabinets 1014 so that a set of one or more fans each move air out of the cabinet 1014 housing a server 1011.

[0187] The heating in the air 1013 is absorbed into a liquid by a first air-to-liquid heat exchanger 1030 arranged on the rack 1010. The air-to-liquid heat exchanger 1030 receives the liquid from a first circuit 1031 connected to the liquid cooling system according to the present disclosure and transfers the heated liquid back to the first circuit 1031. The first air-to-liquid heat exchanger may also comprise a plurality of fans 1015 configured to move air from the cabinets 1014 to pass over the heat exchanger. In another aspect, two or more air-to-liquid heat exchangers 1030 may be arranged on the rack 1010.

[0188] Figure 4b illustrates one embodiment of a liquid-cooler unit 1045, the top illustration illustrates the unit as it is illustrated in the following figures and the bottom illustration illustrates the components of the unit.

[0189] The liquid-cooler unit 1045 is connected to a second circuit 1041 , wherein liquid is transferred to and away from the liquid-cooler unit 1045 through the second circuit 1041. The respective inlet and outlet to the liquid-cooler unit 1045 may be provided with shut-off valves 1045a enabling the liquid-cooler unit 1045 to be easily serviced and / or replaced without requiring a drain of all liquid from the circuits.

[0190] The liquid-cooler unit 1045 comprises one or more liquid cold-plates 1040 configured to be in thermal communication with heat-intensity devices of the servers and configured to absorb heat from the heat-intensity devices. Each liquid cold-plate 1040 may be connected via quick couplers 1045c to a manifold 1045b. The manifold 1045b is configured to enable a plurality of liquid cold-plates 1040 to be connected in parallel. The quick couplers 1045c are configured to enable quick connection and disconnection of channels or tubes connecting the liquid cold-plates 1040 to the manifold 1045b. In one aspect, two or more liquid cold-plates 1040 may be connected in series between two quick couplers 1045c, so that a single pair of channels or tubing is provided into a cabinet in order to cool two or more heat-intensity devices.

[0191] Figure 5a illustrates one embodiment of a liquid cooling system 1001 for extracting heat from a server 1011 arranged in a rack 1010 (as illustrated in fig. 4a), wherein the liquid cooling system comprises a circuit 1020 comprising a plurality of channels configured to guide a flow of liquid. The circuit 1020 comprises a liquid inlet 1022 wherein liquid may be received into the circuit 1020, and a liquid outlet 1023 wherein liquid may be transferred out of the circuit 1020. The circuit 1020 may comprise a circuit pump 1024 configured to maintain the flow of the liquid through the circuit 1020.

[0192] The liquid cooling system 1001 comprises a first air-to-liquid heat exchanger 1030 arranged on a first circuit 1031 and configured to absorb heat from air 1013 within the cabinet 1014 housing the server 11 (as illustrated in fig. 4a). The first circuit 1031 is connected to the circuit 1020.

[0193] The liquid cooling system 1001 comprises a liquid cooling unit 1045 comprising one or more liquid-cold plates 1040 (as illustrated in fig. 4b) arranged on a second circuit 1041 and configured to absorb heat from one or more heat-intensity devices arranged in the one or more servers 1011. The first circuit 1031 is serially connected by a liquid channel 1021 to the second circuit 1041 , so that the one or more liquid cold-plates 1040 are downstream to the air-to-liquid heat exchanger 1030 relative to the flow of the liquid.

[0194] Figure 5b illustrates one further embodiment of the liquid cooling system 1001 , wherein the first circuit 1031 and / or the second circuit 1041 comprises a pump 1034, 1044 configured to control the flow of the liquid through the respective circuits. Furthermore, the first circuit 1031 comprises a first recirculation channel 1032 and a first valve unit 1033 configured to adjust an amount of liquid being recirculated from a downstream position to an upstream position relative to the air-to-liquid heat exchanger 1030. The second circuit 1041 may comprise a second recirculation channel 1042 and a second valve unit 1043 configured to adjust an amount of liquid being recirculated from a downstream position to an upstream position relative to the liquid cold-plates 1040. The pumps 1034, 1044 may be configured to increase and / or decrease the flow of the recirculated liquid.

[0195] Figure 5c illustrates one further embodiment of the liquid cooling system 1001 , wherein the circuit 1020 comprises one or more temperature sensors 1026, flow sensors 1027 and / or pressure sensors 1028 configured to measure the temperature, flow and pressure of the liquid flowing through the channels of the circuit 1020.

[0196] The one or more sensors may be arranged to measure the temperature, flow and / or pressure of the liquid being received at the liquid inlet 1022 and the liquid outlet 1023. Furthermore, the sensors may also measure the flow and / or pressure upstream and downstream relative to the circuit pump 1024 and / or the pumps 1034, 1044 in order to determine a differential pressure across the pumps, wherein the differential pressure may be used to control the pumps efficiently. Measurement of the flow of the liquid at two independent and spaced apart positions may be used to determine if a leak is occurring in the one or more circuits.

[0197] The first circuit 1031 and the second circuit 1041 may also comprise one or more temperature sensors 1036, 1046; flow sensors 1037, 1047 and / or pressure sensors 1038, 1048 configured to measure the temperature, flow and / or pressure of the liquid, respectively. Sensor measurements may be used to control the amount of recirculation through the first and / or second valve units 1033, 1043. Furthermore, the temperature measurements may be used to control the pumps 1034, 1044 so that the liquid flows at a slower speed which increases the heat absorption in the air-to-liquid heat exchanger 1030 and / or the liquid coldplates 1040 and thus yields a higher temperature of the liquid which is transferred to the liquid outlet 1023.

[0198] The liquid cooling system 1001 may also comprise a bypass channel 1051 configured to connect to a downstream position relative to the air-to-liquid heat exchanger 1030 and an upstream position relative to the liquid cold-plates 1040 so that the bypass channel 1051 provides a flow of liquid from the air-to-liquid heat exchanger 1030 directly to the liquid outlet 1023. The bypass channel 1051 comprises a bypass valve 1053 configured to adjust the flow of liquid through the bypass channel 1051 . The bypass channel 1051 may be used to bypass the liquid cold-plate 1040 and / or to mix the higher temperature liquid flowing downstream from the liquid cold-plate 1040 with a slightly lower temperature liquid flowing downstream from the air-to-liquid heat exchanger 1030. One advantage of providing a bypass channel 1051 is that the liquid cooling system 1001 may be used for one or more racks 1010 which do not comprise servers 1011 with one or more heat-intensity devices.

[0199] A further advantage of the bypass channel 1051 is that the liquid cooling system 1001 may continue to circulate liquid for cooling and heat extraction through the one or more air-to- liquid heat exchangers 1030, 1035. This may be useful in scenarios where the second circuit 1041 is being serviced or the heat-intensity devices are not running and therefore do not require cooling by the liquid cold-plates 1040.

[0200] A further advantage of providing a bypass channel 1051 enabling an amount of the liquid flowing from the air-to-liquid heat exchanger 1030 to be bypassed while a remaining amount flows to the liquid cold-plates is that the liquid cooling system 1001 is more flexible. In one scenario, the air-to-liquid heat exchangers 1030 may require a larger flow of liquid than the liquid cold-plates 1040 require, then a part of the excess liquid flow from the air-to-liquid heat exchanger 1030 may flow through the bypass channel 1051 .

[0201] Figure 5d illustrates one further embodiment of the liquid cooling system 1001 , wherein the system comprises a second air-to-liquid heat exchanger 1035 configured to absorb heating from a second rack. The second air-to-liquid heat exchanger 1035 is arranged on an additional circuit 1031a arranged in parallel to the first air-to-liquid heat exchanger 1030, i.e., the two heat exchangers 1030, 1035 are connected to the same upstream position of the circuit 1020 and the same downstream position of the liquid channel 1021 wherein the upstream and downstream positions are relative to the heat exchangers 1030, 1035.

[0202] One advantage of providing a second air-to-liquid heat exchanger 1035 in parallel to the first air-to-liquid heat exchanger is that the temperature of the liquid provided to the one or more liquid cold-plates 1040 may be at a higher temperature and thus enabling the temperature of the liquid being transferred out of the liquid cold-plates 1040 to be at a higher temperature. A further advantage is that a larger volume of liquid flows to the liquid cooling unit 1045, ensuring that the flow of liquid may be as high as possible.

[0203] The flow of the liquid from the second air-to-liquid heat exchanger 1035 may flow through the bypass channel 1051 or the liquid channel 1021 , the flow through one or both channels 1021 , 1051 is controlled by the bypass valve 1053.

[0204] The one or more circuits 1020, 1031 , 1031a, 1041 may comprise check valves 1039, 1049, 1059 configured to block liquid from flowing from a downstream position to an upstream position. Le., the check valves 1039, 1049, 1059 ensure that the liquid only flows in the intended direction. E.g., a third check valve 1059 ensures that liquid downstream to the first air-to-liquid heat exchanger does not flow backwards to the second air-to-liquid heat exchanger 1035; the first check valve 1029 ensures that recirculated liquid does not flow into the liquid channel 1021 and backwards from the liquid cold-plate to the first air-to-liquid heat exchanger 1030 and / or the bypass channel 1051 ; and a second check valve 1049 ensures that liquid flowing from the bypass channel 1051 to the liquid outlet 1023 does not flow backwards to the liquid cold-plate 1040 and / or the second valve unit.

[0205] Figure 6a illustrates one embodiment of a method 1000 for extracting heat from a rack with a server, wherein the method comprises the steps of:

[0206] - providing 1100 a rack with a server, the rack comprising an air-to-liquid heat exchanger and the server comprising a heat-intensity device with a liquid cold-plate;

[0207] - generating 1200 a liquid flow from the air-to-liquid heat exchanger through the liquid coldplate; and

[0208] - adjusting 1300 the liquid flow to have a liquid temperature exiting the liquid cold-plate above 50 degrees Celsius.

[0209] Figure 6b illustrates further embodiments of the method 1000, wherein the method comprises a further step of:

[0210] - recirculating 1400 part of the liquid through the air-to-liquid heat exchanger and / or the liquid cold-plate. Furthermore, the method 1000 may comprise a further step of:

[0211] - utilising 1500 the liquid flow with the liquid temperature above 50 degrees Celsius for heating such as for heat consumers in district heating or industrial greenhouses or swimming pools or office installation or other industrial applications.

Claims

CLAIMS1. A heat-and-cooling system (1) for transferring heat from a heat producer (11 ) to a heat consumer (21) and for transferring cooling to the heat producer (11), wherein the heat-and- cooling system (1) comprises:- a heat-producing section (10) comprising one or more heat producers (11 ) configured to provide a first liquid (16) at a first heat-outlet (12) and receive a return-liquid at a return inlet (13);- a heat-consuming section (20) comprising a consumer return (23) and a second heat-outlet (22) wherein the second heat-outlet is configured for transferring a second liquid (26) to a heat consumer (21 ) and the consumer return is configured for receiving a return-liquid from the heat consumer (21); and- a heat-transferring section (30) arranged between the heat-producing section (10) and the heat-consuming section (20), wherein the heat-transferring section comprises:- a passive liquid-to-liquid heat exchanger (40) comprises at least two inlets (41 ,43) and outlets (42,44) and is configured to transfer heat from the first liquid (16) to the second liquid (26), wherein the first fluid flows through the first inlet (41) and the first outlet (43) and the second fluid flows through the second inlet (43) and the second outlet (44); and- a series of heat pumps comprising at least one or more heat pumps (50,60) configured for transferring heat from the first liquid (16) to the second liquid (26), wherein a first heat pump (50) is downstream to the passive liquid-to-liquid heat exchanger (40), wherein the first liquid flows to the return inlet (13) and the second liquid flows to the second heat-outlet (22).

2. The heat-and-cooling system (1) according to claim 1 , wherein the series of heat pumps comprises two or more heat pumps (50,60), wherein a second heat pump (60) is downstream to the first heat pump (50) relative to the flow of the first liquid (16) and between the passive liquid-to-liquid heat exchanger (40) and the flow of the first heat pump relative to the second liquid (26).

3. The heat-and-cooling system (1 ) according to claim 1 or 2, wherein the heat-producing section (10) comprises a buffer-storage (14) configured to store a medium (15) configured for providing cooling to the heat producer (11).

4. The heat-and-cooling system (1) according to any one of the preceding claims, wherein the heat-consuming section (20) comprises a heat buffer-storage (24) configured to store a heated-medium (25), wherein the heat buffer-storage is configured to store heat by receivingthe second liquid (26) from the first heat pump (50) and to provide the stored heat to the heat consumer (21 ).

5. The heat-and-cooling system (1) according to any one of the preceding claims, wherein the system (1) comprises a closed loop (71) comprising a second passive liquid-to-liquid heat exchanger (70) configured to provide cooling and / or heat to the first liquid (16) and is connected to the first heat-outlet (12) and the return inlet (13), wherein a third liquid circulates the closed loop (71) and the closed loop comprises a generator unit (72) configured to provide cooling and / or heat to the third liquid.

6. The heat-and-cooling system (1) according to any one of the preceding claims, wherein the system (1) comprises one or more temperature sensors configured to measure a temperature of the first liquid (16) and the second liquid (26) and a controller configured to adjust the operation of the one or more heat pumps (50,60) as a function of a temperature of the second liquid (26) transferred to the second heat-outlet (22).

7. The heat-and-cooling system (1 ) according to claim 6, wherein the temperature of the second liquid (26) transferred to the second heat-outlet (22) is in the range of 50 to 90 degrees Celsius, or 65 to 85 degrees Celsius, or 70 to 80 degrees Celsius.

8. The heat-and-cooling system (1 ) according to any one of claims 6 or 7, wherein the controller is configured to adjust the operation of the one or more heat pumps (50,60) as a function of a temperature of the return-liquid returned to the return inlet (13).

9. The heat-and-cooling system (1 ) according to claim 8, wherein the temperature of the return-liquid returned to the return inlet (13) is in the range of 5 to 45 degrees Celsius, 8-40 degrees Celsius, 30-45 degrees Celsius, or 19 to 23 degrees Celsius, or 20 to 22 degrees Celsius.

10. A method (100) of transferring heat from a heat producer (11) to a heat consumer (21) and for transferring cooling to the heat producer (11 ), wherein the method comprises steps of:- providing (110) a first liquid (16) configured to conduct heat from the heat producer (11);- transferring (120) heat from the first liquid (16) to a second liquid (26) through a passive liquid-to-liquid heat exchanger (40), wherein the second liquid is transferred to the heat exchanger (40) from the heat consumer (21);- circulating (130) the first and second liquid (16,26) from the liquid-to-liquid heat exchanger (40) to a series of heat pumps comprising at least two or more heat pumps (50,60); and- transferring (140) heat from the first liquid (16) to the second liquid (26) through the series of heat pumps (50,60), wherein the second liquid (26) is transferred to a heat consumer (21) and the first liquid (16) is returned to the heat producer (11 ).

11. The method (100) according to claim 10, wherein the method comprises further steps of:- storing (150) cooling of the first liquid (16) in a buffer-storage (14); and- transferring (160) cooling from the buffer-storage (14) to the first liquid (16) and transferring the first liquid to the heat producer (11).

12. The method (100) according to claim 10 or 11 , wherein the method comprises further steps of:- storing (155) thermal energy of the second liquid (26) in a heat buffer-storage (24); and- transferring (165) thermal energy from the heat buffer-storage (24) to the second liquid (26) and transferring the second liquid to the heat consumer (21).

13. The method (100) according to any one of claims 10-12, wherein the method comprises a further step of providing (170) cooling and / or heat to the first liquid (16) by circulating the first liquid to a second liquid-to-liquid heat exchanger (70) connected to closed loop (71) comprising a generator unit (72) configured to provide cooling and / or heat to a third liquid in the closed loop.

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