Precision air conditioning system and methods for its operation

Abstract

The invention relates to a precision air conditioning system and a method for its operation, which enables the recovery of usable heat from the waste heat generated during operation in the coolant circuit of the precision air conditioning system by means of a heat exchanger unit (41) of a heat recovery module (40). The heat recovery module (40) has a control unit (46) by means of which a coolant return main valve (43), a recooler bypass valve (44), and a heat exchanger bypass valve (45) are controlled to provide the usable heat as needed. The precision air conditioning system with the heat recovery module is intended in particular for the air conditioning of data centers.

Description

[0001] The invention relates to a precision air conditioning system with a heat recovery module and a method for operating the precision air conditioning system. The application area of ​​the precision air conditioning system with the heat recovery module is, in particular, the air conditioning of data centers, i.e., the cooling of the IT equipment located in the data centers, for example, servers and other IT components.

[0002] Precision air conditioning systems for data centers are typically operated on the principle of indirect free cooling. This means that the waste heat from the data center is dissipated to the environment via a chiller without any air exchange with the surrounding air or outside air. Such precision air conditioning systems for indirect free cooling in data centers usually consist of precision air conditioning units within the data center, chillers outside the building, and pumps that circulate a refrigerant or heat transfer fluid in a closed loop between the precision air conditioning units and the chiller. The precision air conditioning units are equipped with fans that circulate the air within the data center; they contain a closed refrigeration circuit (with compressors and evaporators) as well as a free cooling coil for free cooling operation.Cooling via the internal refrigeration cycle is only activated when free cooling is no longer sufficient.

[0003] The primary function of precision air conditioning units is to extract heat from the data center, thereby maintaining the temperature of the IT equipment, especially the servers, at a suitable level. The absorbed heat is then transported out of the data center and released into the ambient air via the cooling tower.

[0004] The primary focus in the data center industry is on energy-efficient cooling. Indirect free cooling offers the possibility of cooling the data center—at a suitable ambient temperature—with a cold refrigerant, such as water or a water-glycol mixture. Cooling in the precision air conditioning units then takes place via the respective free cooling coil. Forced cooling via the internal refrigeration circuit—and thus the energy-intensive operation of the compressors in the refrigeration circuit of the precision air conditioning units—is avoided. In this way, the precision air conditioning units operate as energy-efficiently as possible. If the outside temperature rises and the refrigerant is no longer cold enough to cool the data center, the compressors in the refrigeration circuit are switched on, and the temperature in the data center is maintained at a suitable level.

[0005] The heat absorbed by the refrigerant as it passes through the precision air conditioning units is released to the ambient air via the recooler. However, this process of heat release to the ambient air results in a loss of thermal energy. Instead of releasing this energy unused into the outside air, it can also be used for heat recovery.

[0006] US 2022 / 0205686A1 discloses a heating, ventilation, air conditioning, and cooling system comprising a heating fluid circuit, a cooling fluid circuit, and a storage fluid circuit. A cooling fluid absorbs heat energy from a room to be air-conditioned and transfers it to the storage fluid circuit via a heat exchanger.

[0007] Also known from DE 10 2010 003 915 A1 is a refrigeration system with a closed refrigerant circuit, which, in the direction of refrigerant flow, comprises a compressor unit, a heat exchanger of a heat recovery system, a condenser, a receiver, an expansion device, and an evaporator. A control valve, connected to a control device, is arranged between the heat exchanger of the heat recovery system and the condenser.

[0008] The object of the invention is to provide a system or device for heat recovery from the waste heat of a precision air conditioning system, which, when the precision air conditioning system is in operation, makes it possible to ensure the required cooling of the building or room to be air-conditioned, in particular a data center, and at the same time to supply the waste heat as usable heat to a consumer as required.

[0009] This problem is solved by a precision air conditioning system according to claim 1 and a method for operating the precision air conditioning system according to claim 6. Advantageous embodiments of the invention are set out in claims 2 to 5, 7 and 8.

[0010] According to the invention, a heat recovery module is integrated into the precision air conditioning system.

[0011] The precision air conditioning system comprises one or more precision air conditioning units for cooling the building or room to be air-conditioned, i.e., cooled, particularly a data center; a cooling unit with one or more cooling towers; and a pump unit with one or more coolant pumps. The precision air conditioning units are connected to the cooling towers in a closed coolant circuit, with the coolant pumps integrated into the coolant return line leading from the precision air conditioning units to the cooling towers. From the cooling tower, the cooled coolant flows back to the precision air conditioning units via the coolant supply line. Water or water-glycol mixtures serve as the coolant.

[0012] The installation position of the heat recovery module according to the invention is located in the coolant circuit on the return side downstream of the coolant pumps, i.e., a section of the coolant return and a section of the coolant supply are integral parts of the heat recovery module, or the heat recovery module has a coolant return section and a coolant supply section that can be integrated into or are integrated into the coolant circuit of the precision air conditioning system.

[0013] The heat recovery module comprises a heat exchanger bypass connected to the coolant return line. At one end, the bypass branches off from the coolant return line at a first heat exchanger bypass branch point and leads from there to a heat exchanger unit of the heat recovery module, before returning to the coolant return line. At the other end, the heat exchanger bypass branches back into the coolant return line at a second heat exchanger bypass branch point, downstream of the first. The heat exchanger bypass forms the primary side of the heat exchanger unit.

[0014] The secondary side of the heat exchanger unit is connected to the consumer circuit, which is fluidically separated from the heat exchanger bypass and can be connected to a consumer. The heat exchanger unit, which is designed, for example, as a plate heat exchanger, transfers the waste heat from the cooling process from the refrigerant to the consumer circuit, more precisely to a heat transfer fluid, such as water, circulating within the consumer circuit. The consumer can then draw the waste heat from the precision air conditioning system as usable heat from this consumer circuit as needed.

[0015] The heat recovery module also features a coolant return main valve integrated into the coolant return between the first and second heat exchanger bypass branch for controlling the coolant flow in the coolant return, as well as a heat exchanger bypass valve integrated into the heat exchanger bypass for controlling the coolant flow in the heat exchanger bypass.

[0016] Furthermore, the heat recovery module includes a recooler bypass leading from the coolant return to the coolant supply, bypassing the recoolers. This bypass branches off from the coolant return downstream of the second heat exchanger bypass branch at one end and connects to the coolant supply at the other. A recooler bypass valve, designed as a mixing valve, is installed at the point where it connects to the coolant supply. This means that the recooler bypass valve is connected to the coolant supply line from the recoolers, the recooler bypass itself, and the coolant supply line returning to the precision air conditioning units.The recooler bypass valve serves to control the flow of coolant in the recooler bypass, to ensure the correct recirculation of the coolant into the coolant supply line, and to mix the coolant flowing from the recooler-side branch of the coolant supply line with the coolant flowing via the recooler bypass. Therefore, the recooler bypass valve can control both the flow of coolant from the recooler-side branch of the coolant supply line to the air conditioning unit-side branch of the coolant supply line, and the flow of coolant from the recooler bypass to the air conditioning unit-side branch of the coolant supply line.

[0017] The heat recovery module also has a control unit that is connected to the coolant return main valve, the recooler bypass valve, and the heat exchanger bypass valve for their connection and / or adjustment. According to the invention, the control unit is configured to adjust the coolant flow through the heat exchanger unit by means of the coolant return main valve, the recooler bypass valve, and the heat exchanger bypass valve so that the coolant is selectively recooled by means of the heat exchanger unit, with heat being transferred to the consumer circuit. That is, the waste heat generated in the precision air conditioning system, which in prior art air conditioning systems is simply dissipated to the environment via the recooler(s), can be transferred to the consumer as usable heat, particularly for heating purposes, by means of the heat recovery module.For reasons of ease of control, the coolant return main valve, the recooler bypass valve and the heat exchanger bypass valve are preferably designed as motor-driven valves.

[0018] The precision air conditioning system according to the invention comprises the described heat recovery module, the precision air conditioning unit(s) for cooling the room to be air-conditioned, the recooling unit, and the pump unit. These components are interconnected in the closed refrigerant circuit.

[0019] By using the proposed heat recovery module in the precision air conditioning system, or by combining the precision air conditioning system with the heat recovery module, the waste heat from the cooling circuit (which typically uses water as a coolant) is made available to the user as usable heat when needed. For example, the operator of a data center can cool it and simultaneously decouple the resulting waste heat and utilize it for their own purposes. The heat recovery module thus contributes to the sustainable operation of the precision air conditioning system.

[0020] The design of the refrigerant circuit within precision air conditioning units offers a further advantage: These units typically feature a closed, internal refrigeration circuit, separate from the refrigerant of the main circuit, containing at least one compressor and at least one evaporator, as well as a free cooling coil. When cooling the room to be air-conditioned, heat can be transferred from the room to the refrigerant via the free cooling coil, or – if the cooling capacity of the free cooling coil is insufficient – ​​the room can be cooled using the closed internal refrigeration circuit, simultaneously transferring heat to the refrigerant.Since the precision air conditioning units have both the compressors of the internal refrigeration circuit and the free cooling coils, the room to be air-conditioned, e.g., the data center, can continue to be cooled partially or completely via the free cooling coils of the precision air conditioning units in the event of compressor failure. Thus, the invention fulfills not only the benefit of heat recovery but also that of a redundant cooling system.

[0021] To effectively utilize the waste heat, it is recommended to operate the precision air conditioning system with coolant temperatures at the inlet to the heat recovery module of up to 70 °C, preferably in the range of 50 °C to 70 °C.

[0022] In the consumer circuit, the heat transfer fluid, for example water, is circulated between the heat exchanger and the consumer. A storage unit, such as a container or tank filled with the heat transfer fluid and optionally containing other heat storage materials, may be installed on the consumer side of the circuit. The circulation of the heat transfer fluid within the consumer circuit is preferably achieved by a pump integrated into the circuit, which is connected to the control unit for its operation.

[0023] To carry out the inventive method for operating the precision air conditioning system described above, the consumer circuit of the heat recovery module is connected to the consumer. The consumer requests, or can request, a required heat output from the heat recovery module via the control unit.

[0024] The control and regulation unit regulates the flow of coolant through the heat exchanger unit by means of the coolant return main valve, the recooler bypass valve and the heat exchanger bypass valve depending on the required heat output of the consumer and a waste heat output currently provided by the coolant circuit of the precision air conditioning system.

[0025] The coolant return main valve, the recooler bypass valve and the heat exchanger bypass valve are adjusted by the control unit according to the procedure described below for the alternative operating conditions: Unless the consumer demands heat output, the heat exchanger bypass valve remains closed. The recooler bypass valve opens the recooler-side branch of the coolant supply. In this operating condition, the coolant is therefore recooled by the recoolers.

[0026] If the required heat output from the consumer is equal to or greater than the waste heat output currently supplied by the refrigerant circuit of the precision air conditioning system, the heat exchanger bypass valve is fully open, the refrigerant return main valve is closed, and the recooler bypass is fully open via the recooler bypass valve. The recooler bypass valve simultaneously shuts off the recooler-side branch of the refrigerant supply. In this operating condition, the refrigerant is therefore recooled by the heat exchanger unit.

[0027] Provided that the required heat output from the consumer is available and less than the waste heat output currently supplied by the refrigerant circuit of the precision air conditioning system, the heat exchanger bypass valve, the refrigerant return main valve, and the recooler bypass are partially opened or remain partially open via the recooler bypass valve. The recooler bypass valve simultaneously partially opens the recooler-side branch of the recooler supply. In this operating condition, the refrigerant is cooled by both the heat exchanger unit and the recooler(s). The control unit is designed to distribute the refrigerant flow in such a way as to meet the consumer's required heat output.

[0028] According to one embodiment of the heat recovery module, it features a supply temperature sensor connected to the control unit for measuring the coolant supply temperature. The supply temperature sensor is located in the coolant supply line downstream of the recooler bypass valve.

[0029] Using the supply temperature sensor and measuring the coolant supply temperature with the supply temperature sensor, the operating procedure for the described precision air conditioning system can be further implemented such that, provided no heat output is requested by the consumer and the coolant supply temperature measured at the supply temperature sensor is less than or equal to 0 °C, the heat exchanger bypass valve is closed or remains closed, the coolant return main valve is fully opened or remains closed, and the recooler bypass is partially opened or remains closed by means of the recooler bypass valve. The recooler bypass valve simultaneously partially opens the recooler-side branch of the coolant supply. The advantage of this supplementary control is that the coolant-carrying lines in the air-conditioned room are less prone to condensation.Condensation on pipes is largely avoided.

[0030] The invention is explained in more detail below with reference to an exemplary embodiment and to the schematic drawings, wherein identical or similar features are provided with the same reference numerals; to this end, the drawings show... Fig. 1: The precision air conditioning system with heat recovery module in flowchart representation, Fig. 2: The precision air conditioning system with heat recovery module during normal cooling operation in flowchart representation, Fig. 3: The precision air conditioning system with heat recovery module during cooling operation at low outside temperatures in flow diagram representation, Fig. 4: The precision air conditioning system with heat recovery module when heating is requested by the consumer, shown in flowchart form. Fig. 5: The precision air conditioning system with heat recovery module during heating operation with balanced heat demand in flow diagram representation, Fig. 6: the precision air conditioning system with heat recovery module during heating operation with increased heat demand in flow diagram representation, and Fig. 7: The precision air conditioning system with heat recovery module for heating operation with low heat demand in flow diagram representation.

[0031] The general meaning of the refrigeration and air conditioning symbols used in the flow diagrams is given in the legend of the respective figure with reference numbers 50 to 78.

[0032] The room to be air-conditioned, room 10 of the precision air-conditioning system according to Fig. System 1 is a data center in which the required temperature for the operation of the IT equipment located within the data center is set by means of precision air conditioning units 11. The waste heat from the precision air conditioning units 11 is transferred to the coolant (water), which is circulated in a closed coolant circuit between the precision air conditioning units 11 and the recooler 31 located in the cooling unit 30 outside the data center – outdoors. The coolant flows from the recooler 31 via the coolant supply line 1 to the precision air conditioning unit 11 and from there via the coolant return line 2 back to the recooler 31. The coolant is circulated in the coolant circuit by means of the coolant pumps 21 located in the pump unit 20 and integrated into the coolant return line 2.

[0033] The heat recovery module 40 is integrated into the coolant return line 2 between the pump unit 20 and the recooling unit 30. The heat recovery module 40 – without the control unit 46 – is located within the dashed outline, and – with the control unit 46 – within the dotted outline. The coolant supply line 1 and the coolant return line 2 within these outlines are both parts of the precision air conditioning system and parts of the heat recovery module 40.

[0034] The heat recovery module 40 comprises the heat exchanger unit 41 in the form of a plate heat exchanger and three valves: the coolant return main valve 43, the recooler bypass valve 44, and the heat exchanger bypass valve 45. The heat recovery module 40 also includes four shut-off valves, four temperature sensors, and two pressure transducers. The control and regulation of the components of the heat recovery module 40 is implemented via the control and regulation unit 46.

[0035] The heat exchanger unit 41 is positioned in the coolant return line 2 between the coolant outlet of the precision air conditioning units 11 or the coolant pumps 21 and the coolant inlet of the recooler 31. The warm coolant (water) is transferred to the heat recovery module 40 via the coolant pumps 21. The coolant reaches the heat exchanger unit 41 via the heat exchanger bypass 4, which branches off from the coolant return line 2 to the heat exchanger unit 41 at the first heat exchanger bypass branch and from there leads back to the second heat exchanger bypass branch in the coolant return line 2. The coolant return main valve 43 is located centrally in the coolant return line 2 between these two heat exchanger bypass branches. The heat exchanger bypass valve 45 is located in the heat exchanger bypass 4 upstream of the heat exchanger unit 41 in the direction of flow.

[0036] From the coolant return line 2, downstream of the second heat exchanger bypass branch of the heat exchanger bypass 4, the recooler bypass 3 branches off from the coolant return line 2 to the coolant supply line 1. Refrigerant can be routed directly back into the coolant supply line 1, i.e., to the precision air conditioning units 11, via the recooler bypass 3 without recooling. At the branch point of the recooler bypass 3 into the coolant supply line 1 is the recooler bypass valve 44, which is designed as a mixing valve to mix the refrigerant from the incoming lines, i.e., from the recooler bypass 3 and the recooler-side line of the coolant supply line 1, or to close off individual lines.

[0037] By means of the heat exchanger unit 41, heat or waste heat from the coolant in the recooler bypass 3 is transferred to the consumer circuit 5 or the heat transfer fluid circulating in consumer circuit 5; consumer circuit 5 forms the secondary side of the heat exchanger unit 41. When the consumer 47 requests heat output, the coolant is routed through the heat exchanger unit 41 and the extracted heat from the consumer 47 is drawn from consumer circuit 5 as usable heat. On the consumer side, the tank 48, designed as a heat storage tank and heat transfer fluid reservoir, is installed in consumer circuit 5.

[0038] The recooler bypass valve 44 acts as a mixing valve to quickly and efficiently bring the coolant temperature to a suitable level. The recooler bypass valve 44 is controlled by the supply temperature sensor 49, which is located on the coolant inlet side of the precision air conditioning units 11. Monitoring the coolant inlet temperature ensures that the compressors of the precision air conditioning units 11 are not supplied with excessively warm coolant, which could potentially lead to high-pressure faults.

[0039] The heat exchanger bypass valve 45 ensures that the heat exchanger unit 41 is supplied with warm coolant when required. Conversely, the coolant return main valve 43 ensures that the heat exchanger unit 41 is bypassed if no heat output is requested by the consumer. This prevents unnecessary pressure losses that would lead to inefficient pump operation.

[0040] The control and regulation unit 46 is connected to the components of the heat recovery module 40 for measuring temperatures and for controlling and regulating the actuators in the heat recovery module 40. Depending on the temperatures at the in Fig. The coolant return main valve 43, the recooler bypass valve 44, the heat exchanger bypass valve 45, and the feed pump 42 in the consumer circuit are controlled or regulated at the temperature measuring points shown in Figure 1. This allows the temperatures in the Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6 to Fig. The 7 described operating states of the precision air conditioning system can be realized.

[0041] In Fig. Figure 2 illustrates the scenario for normal cooling operation: The operator only wants to cool the room to be air-conditioned, i.e., their data center; there is no need at the consumer 47 to utilize the waste heat generated from the cooling process. The recooler bypass valve 44 and the heat exchanger bypass valve 45 are closed; the coolant return main valve 43 is open. In this case, the waste heat is routed directly to the recooler 31 and released into the ambient air.

[0042] Fig. Figure 3 represents a scenario in which the ambient temperature falls below 0 °C (“sub zero”): The operator only wants to cool the rooms of its data center; there is no need at the consumer 47 to utilize the waste heat generated from the cooling process. The coolant temperature (water temperature) is cold enough to operate the precision air conditioning units 11 in free cooling mode, i.e., via the free cooling coils of the precision air conditioning units 11. Under certain circumstances, the coolant supply temperature (water temperature) measured at the supply temperature sensor 49 is so low that condensation can occur on the pipes within the data center. To warm the coolant (water) slightly, coolant from the coolant return line 2, after exiting the precision air conditioning units 11, is partially fed back into the coolant supply line 1 via the recooler bypass 3.Coolant supplied via coolant supply line 1, cooled in the recooler 31, is mixed with coolant from the recooler bypass 3 in the recooler bypass valve 44 to raise the coolant supply temperature. Since there is no heating demand at consumer 47, the heat exchanger bypass valve 45 is closed. The coolant return main valve 43 is open. The recooler bypass valve 44 (mixing valve) regulates until a suitable coolant supply temperature level is reached. The recooler bypass 3 is partially open. Excess heat is dissipated to the ambient air through partial circulation via the recooler 31.

[0043] In Fig. Figure 4 depicts a scenario in which the consumer 47 requests heat recovery. To bring the refrigerant temperature (water temperature) up to a suitable level of up to 70°C as quickly as possible, the compressors in the precision air conditioning units 11 start up. The refrigerant is fed back from the refrigerant return line 2, after exiting the precision air conditioning units 11, into the refrigerant supply line 1 via the fully open recooler bypass 3; that is, no cooling takes place via the recoolers 31. The heat exchanger bypass valve 45 is closed; the refrigerant return main valve 43 and the recooler bypass valve 44 are open. This operating condition shortens the compressor start-up ramp and brings the refrigerant temperature up to the desired temperature as quickly as possible.

[0044] In Fig. Figure 5 illustrates the scenario in which the waste heat from cooling operation matches the heating demand of consumer 47: If the required heat output, i.e., the consumer demand, corresponds to the waste heat output currently supplied by the refrigerant circuit of the precision air conditioning system, the entire quantity of refrigerant is routed through the heat exchanger unit 41. The refrigerant return main valve 43 is closed; the heat exchanger bypass valve 45 is open. The recooler bypass valve 44 is also open, as all the waste heat has been transferred to the consumer circuit and the refrigerant can be transferred via recooler bypass 3 to the refrigerant supply 1 and thus to the precision air conditioning units 11. Circulation via the recoolers 31 is unnecessary, as this could potentially cause the refrigerant temperature to drop further, leading to inefficient operation of the compressors in the precision air conditioning units 11., the recooler bypass valve 44 blocks the coolant flow via the recooler 31.

[0045] In Fig. Figure 6 illustrates the scenario in which the required heat output exceeds the waste heat output currently provided by the coolant circuit of the precision air conditioning system: If the required heat output is higher than the provided waste heat output, the entire quantity of coolant is circulated through the heat exchanger unit 41 to provide the consumer 47 with maximum output. The coolant return main valve 43 is closed; the heat exchanger bypass valve 45 is open. The recooler bypass valve 44 is also open to return the coolant to the precision air conditioning units 11 as quickly as possible, so that the consumer 47 receives the required heat output. Circulation through the recooler 31 does not occur, as this could potentially lower the water temperature further; i.e., the recooler bypass valve 44 blocks the coolant flow through the recooler 31.

[0046] Fig.Figure 7 illustrates the scenario in which the waste heat currently supplied by the refrigerant circuit of the precision air conditioning system exceeds the required heat output of the consumer 47: If the required heat output is less than the supplied waste heat output, only a portion of the refrigerant is routed through the heat exchanger unit 41. All three valves—namely, the refrigerant return main valve 43, the recooler bypass valve 44, and the heat exchanger bypass valve 45—regulate and adjust the waste heat output discharged through the heat exchanger unit 41 to the required heat output of the consumer 47. The recooler bypass valve 44 ensures that the refrigerant supply temperature in the refrigerant supply line 1, i.e., on the refrigerant inlet side of the precision air conditioning units 11, remains at a suitable level to maximize compressor operation.The coolant return main valve 43 directs the excess waste heat to the recoolers 31. The heat exchanger bypass valve 45 transfers precisely the required heat output via the heat exchanger unit 41, which is needed by the consumer 47. Reference symbol list 1 Coolant supply 2 Coolant return 3 Recooler Bypass 4 Heat exchanger bypass 5 Consumer group 10 rooms to be air-conditioned 11 Precision air conditioner 20 pump units 21 coolant pumps 30 Cooling unit 31 cooling units 40 Heat recovery module 41 Heat exchanger unit 42 Pump in the consumer circuit 43 Coolant return main valve 44 Recooler bypass valve 45 Heat exchanger bypass valve 46 Control and regulation unit 47 consumers 48 Tank 49 Flow temperature sensor 50 pump 51 Climate cabinet 52 Shut-off valve, general 53 Valve with manual actuator 54 Valve with ball valve 55 Balancing valve 56 Overflow valve with spring 57 Compensator 58 regulators 59 manometers 60 heat exchangers 61 Fan coil unit 62 Shut-off valve 63 Valve with motor drive 64 Three-way valve 65 Check valve 66 Safety valve 67 Expansion vessel 68 Thermometer 69 pressure sensors 70 Cooling tower 71 Recoolers 72 Butterfly valve 73 Valve with magnetic drive 74 Cap valve 75 Check valve 76 mud flaps 77 containers (general) 78 temperature sensors

Claims

Precision air conditioning system comprising a heat recovery module (40), wherein the precision air conditioning system comprises one or more precision air conditioning units (11) for cooling a room (10) to be air-conditioned, a recooling unit (30) with one or more recoolers (31), and a pump unit (20) with one or more coolant pumps (21), the precision air conditioning units (11) being connected to the recoolers (31) via a closed coolant circuit carrying a coolant, comprising a coolant supply (1) from the recoolers (31) to the precision air conditioning units (11) and a coolant return (2) from the precision air conditioning units (11) to the recoolers (31), wherein each of the precision air conditioning units (11) has an internal closed refrigeration circuit with at least one compressor and at least one evaporator, as well as a free cooling coil.- the coolant pumps (21) are integrated into the coolant return (2) of the precision air conditioning system, - the installation position of the heat recovery module (40) in the coolant circuit is arranged on the return side downstream of the coolant pumps (21), wherein a section of the coolant return (2) and a section of the coolant supply (1) are parts of the heat recovery module (40), and - the heat recovery module (40), the precision air conditioning unit(s) (11) for cooling the room (10) to be air-conditioned, the recooling unit (30), and the pump unit (20) are connected to each other in the closed coolant circuit, wherein the heat recovery module (40) comprises: - a heat exchanger bypass (4),which branches off at one end from the coolant return (2) at a first heat exchanger bypass branch point and at the other end branches back into the coolant return (2) at a second heat exchanger bypass branch point located downstream of the first heat exchanger bypass branch point; a coolant return main valve (43) integrated into the coolant return (2) between the first and the second heat exchanger bypass branch points for controlling the flow of coolant in the coolant return (2); a heat exchanger unit (41) to which the heat exchanger bypass (4) is connected on the primary side; a heat exchanger bypass valve (45) integrated into the heat exchanger bypass (4) for controlling the flow of coolant in the heat exchanger bypass (4); a consumer circuit (5) connectable to a consumer (47), which is connected on the secondary side to the heat exchanger unit (41).- a recooler bypass (3) leading from the coolant return (2) to the coolant supply (1), branching off at one end downstream of the second heat exchanger bypass branch point from the coolant return (2) and branching off at the other end into the coolant supply (1), - a recooler bypass valve (44) integrated into the recooler bypass (3) at the branch point to the coolant supply (1), designed as a mixing valve, for controlling the flow of coolant in the recooler bypass (3), for introducing the coolant into the coolant supply (1) in a circulating manner and for mixing the coolant flowing from the recooler-side branch of the coolant supply (1) with the coolant flowing via the recooler bypass (3), - a control and regulation unit (46) which is connected to the coolant return main valve (43), the recooler bypass valve (44) and the Heat exchanger bypass valve (45) is connected to its supply and / or adjustment,wherein the control and regulation unit (46) is configured to adjust the flow of the coolant through the heat exchanger unit (41) by means of the coolant return main valve (43), the recooler bypass valve (44) and the heat exchanger bypass valve (45) so that the recooling of the coolant optionally takes place by means of the heat exchanger unit (41) with heat transfer to the consumer circuit (5). Precision air conditioning system according to claim 1, characterized in that the heat recovery module (40) has a supply temperature sensor (49) connected to the control and regulation unit (46) for measuring the coolant supply temperature, wherein the supply temperature sensor (49) is arranged in the coolant supply (1) downstream of the recooler bypass valve (44). Precision air conditioning system according to claim 1 or 2, characterized in that the heat recovery module (40) has a pump (42) integrated into the consumer circuit (5) and connected to the control unit (46) for its control, for pumping a heat transfer fluid circulating in the consumer circuit (5). Precision air conditioning system according to one of claims 1 to 3, characterized in that the heat exchanger unit (41) is a plate heat exchanger. Precision air conditioning system according to one of claims 1 to 4, characterized in that the coolant return main valve (43), the recooler bypass valve (44) and the heat exchanger bypass valve (45) are motor-driven valves. Method for operating a precision air conditioning system according to one of claims 1 to 5, wherein the consumer circuit (5) of the heat recovery module (40) is connected to the consumer (47) through which a required heat output is requested from the heat recovery module (40) via the control unit (46), characterized in that the control unit (46), depending on the required heat output of the consumer (47) and a waste heat output currently provided by the coolant circuit of the precision air conditioning system, regulates the flow of the coolant through the heat exchanger unit (41) by means of the coolant return main valve (43), the recooler bypass valve (44) and the heat exchanger bypass valve (45) such that—if no required heat output is requested by the consumer (47),the heat exchanger bypass valve (45) is closed or remains closed and the recooler bypass valve (44) releases the recooler-side branch of the coolant supply (1), provided that the required heat output requested by the consumer (47) is equal to or greater than the waste heat output currently provided by the coolant circuit of the precision air conditioning system, the heat exchanger bypass valve (45) is fully released or remains closed, the coolant return main valve (43) is closed or remains closed, and the recooler bypass (3) is fully released or remains closed by means of the recooler bypass valve (44), whereby the recooler bypass valve (44) simultaneously blocks the recooler-side branch of the coolant supply (1), provided that the required heat output requested by the consumer (47) is present and less than the waste heat output currently provided by the coolant circuit of the precision air conditioning system.the heat exchanger bypass valve (45) is partially opened or remains open, the coolant return main valve (43) is partially opened or remains open, and the recooler bypass (3) is partially opened or remains open by means of the recooler bypass valve (44), wherein the recooler bypass valve (44) simultaneously partially opens the recooler-side branch of the coolant supply (1). Method according to claim 6 using the heat recovery module (40) according to claim 2, characterized in that, if no heat output is requested by the consumer (47) and the coolant supply temperature measured at the supply temperature sensor is less than or equal to 0 °C, the heat exchanger bypass valve (45) is closed or remains closed, the coolant return main valve (43) is fully opened or remains closed, and the recooler bypass (3) is partially opened or remains closed by means of the recooler bypass valve (44), wherein the recooler bypass valve (44) simultaneously partially opens the recooler-side branch of the coolant supply (1). Method according to claim 6 or 7, characterized in that the room (10) to be air-conditioned is a data center.

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