GB2579928A

GB2579928A - Heat pump having closed intermediate cooling and method for pumping heat or method for producing the heat pump

Info

Publication number: GB2579928A
Application number: GB2002457.6A
Authority: GB
Inventors: Kniffler Oliver
Original assignee: Efficient Energy GmbH
Current assignee: Efficient Energy GmbH
Priority date: 2017-08-30
Filing date: 2018-08-28
Publication date: 2020-07-08
Anticipated expiration: 2038-08-28
Also published as: GB202002457D0; GB2579928B; DE102017215198A1; WO2019043009A1

Abstract

The invention relates to a heat pump comprising an evaporator (10) for evaporating working fluid, a condenser (20) for condensing compressed working steam; a compressor (30) having a first compressor stage (31), a second compressor stage (33) and a steam chamber (32) between the first compressor stage (31) and the second compressor stage (33); and an intermediate cooler (40) having a heat exchanger (43), which is arranged in the steam chamber (32), and which has a heat exchanger input (41) and a heat exchanger output (42), wherein the heat exchanger input (41) or the heat exchanger output (42) is connected to a condenser input (21) or a condenser output (22) in order to direct cooling fluid for the condenser (20) in a circuit both through the condenser (20) and through the heat exchanger (43) during operation of the heat pump.

Description

Heat Pump with Closed Intermediate Cooling and Method for Pumping Heat or Method for Producing the Heat Pump

Description

The present invention relates to heat pumps and in particular to heat pumps with a multistage compressor and an intermediate cooler.

Fig. 5 shows a heat pump as it can be used for heating, for example. The heat pump includes an evaporator 100, a compressor 110, a liquefier 120 and an expansion valve 130. In the evaporator, an operating liquid circulating in the circuit is evaporated and supplied to the compressor, here exemplarily configured as a piston compressor, via a suction line 112. Compressed operating vapor is then fed into liquefier 120 via a discharge line 114. In the liquefier 120, the operating vapor compressed by the compressor 110 is liquefied. The circuit is closed by an expansion valve 130, which is used to expand the operating liquid at the liquefier output from the high liquefier pressure to the low evaporator pressure.

A heat exchanger with a closed conduit, shown at 102, is arranged in the evaporator 100, liquid that brings heat from the environment, for example, flows across the same. Due to the heat introduced into the evaporator 100, the operating liquid evaporates in the evaporator, whereby heat is withdrawn from the liquid in the heat exchanger 102 and thus cooled operating liquid is discharged from the evaporator via the heat exchanger.

Similarly, the liquefier also has a heat exchanger 122. In the heat exchanger 122, heat introduced into the liquefier 120 by the liquefaction process is discharged from the liquefier to a cooler, which can be a radiator, for example. The operating liquid cooled in the cooler is then fed back into the heat exchanger 122, which is located in the liquefier 120.

In the scenario shown in Fig. 5, environmental heat is introduced into the evaporator and heating heat is discharged from the liquefier. This application of the heat pump is therefore used for heating a building, for example.

The other application of the heat pump, where the heat pump has the same basic structure, serves to cool a building. For this purpose, the "environmental heat", which is introduced into the evaporator 100 via the heat exchanger 102, is the heat in a room to be cooled, such as a computing center. The "heating heat", on the other hand, is the heat supplied to a cooler, which is located on a roof or on the outside of a building, for example. In general, the region thermally connected to the evaporator forms the region to be cooled and the region thermally connected to the liquefier forms the region to be heated.

European patent EP 2 281 155 discloses a vertically arranged heat pump with an evaporator and a liquefier as well as a gas region extending between the evaporator and the liquefier. In particular, the liquefier is located above the evaporator in an operating installation direction of the heat pump. The compressor comprises a first compressor stage, intermediate cooling and a second compressor stage. Energy extracted by the intermediate cooler from the overheated operating vapor after the first compressor stage is used to heat a service water tank to a temperature above the temperature in the liquefier. A return channel is provided for returning the medium, a first stage of the return channel having nozzle openings in the bottom wall of the liquefier, so that liquefied operating fluid located near such a nozzle opening sprays into the intermediate cooler due to the pressure difference between the floor of the liquefier and the intermediate cooler.

The sprayed-in liquid medium is then collected in a bulge of the intermediate cooler, from where it is transported to the evaporator through a second section of the return channel. A similar spraying technique through nozzle openings can be used here as well, since there is again a pressure difference between the gas channel and the evaporator space in the evaporator.

European patent EP 2 016 349 discloses a heat pump using water as the operating liquid and in which a multistage compressor is present, the multistage compressor comprising a first flow engine and an n-th (last) flow engine. In particular, an intermediate cooler is used, which comprises a heat exchanger for heating service water. The flow engines are configured as radial compressors with a rotating impeller, wherein the impeller can be a low-speed radial impeller, a medium-speed radial impeller, a semi-axial impeller or an axial impeller or propeller. In general, a flow engine with a radial impeller is used. For intermediate cooling, one or more heat exchangers are provided to heat the service water.

These heat exchangers are configured to cool the gas heated (and compressed) by a preceding flow engine. For this purpose, the overheating enthalpy is sensibly used to increase the efficiency of the entire compression process. Thus, heat is extracted from the compressed vapor to heat service water to higher temperatures than, for example, 40 °C.

In open intermediate cooling, a coolant, e.g. water, is evaporated, which must be raised to a higher pressure level with the downstream stage. This involves additional compressor capacity. On the other hand, closed intermediate cooling can only cool the overheated water vapor down to saturated vapor if there are sufficiently undercooled large surfaces for heat transport. If cold water is provided for this purpose, the capacity is unfavorably introduced into the system on the cold water side and must be provided as additional cooling capacity.

JPH 06257890 discloses a heat pump that uses water and wherein cooling and heating are performed with the same apparatus. To produce cooled water or ice, part of the water is evaporated and the remaining part of the water is cooled by this, The vapor produced by the evaporation is compressed in several stages and then reaches a liquefier which is coupled to a cooling tower.

US Patent No. 3,665,724 discloses a heating and cooling apparatus having a multistage radial compressor. The latent heat of a coolant is discharged together with the compression heat via a cooling tower.

The object of the present invention is to provide an improved heat pump concept with intermediate cooling that makes more efficient use of available resources.

This object is solved by a heat pump according to claim 1, a method for pumping heat according to claim 18 or a method for producing a heat pump according to claim 19.

The present invention is based on the finding that reaching the saturated vapor temperature after a compressor stage is abandoned. This increases the compressor capacity of the downstream stage due to the less favorable starting conditions. However, a heat exchanger can use the coolant, i.e. the return flow from the region to be heated, to cool down the overheated operating liquid vapor to near the cooling water temperature, which is provided from the roof or comes from the region to be heated, for example. This does not produce water vapor, which would have to be compressed with the downstream stage, but a large part of the overheating enthalpy is already dissipated as heating capacity to the cooling system, e.g. the waste heat system when using a heat pump as cooling or refrigerating machine or the heating system when using a heat pump as heating device.

If the heat exchanger, which is actually used for intermediate cooling, is configured large enough, single-stage operation can already take place via this part of the heat exchanger.

This eliminates the need for switching between single-stage and multistage operation of the heat pump. The only measure that needs to be taken to switch from two-stage operation to single-stage operation, e.g. when respective heating or cooling requirements are moderate, is to switch off the compressor of the downstream stage. Otherwise, no specific measures are needed.

According to the invention, therefore, in a heat pump comprising an evaporator, a liquefier and a compressor with several stages and a vapor space between two compressor stages, an intermediate cooler with a heat exchanger is used which is arranged in the vapor space and which has a heat exchanger input and a heat exchanger output. The heat exchanger input or the heat exchanger output is connected to a liquefier input or a liquefier output in order to guide cooling liquid for the liquefier through both the liquefier and the heat exchanger in a circuit during operation of the heat pump.

Depending on the implementation, the liquefier is an open liquefier in that the water from the heat exchanger of the intermediate cooler is used directly to condense operating vapor compressed by the second compressor stage into this water. In other embodiments, however, the liquefier is a "closed" liquefier. This means that a closed conduit, i.e. again a heat exchanger, is arranged in the liquefier between the liquefier input and the liquefier output, which ensures that the medium flowing in the heat exchanger does not come into direct contact with the compressed operating vapor to be liquefied in the liquefier, but only in thermal contact. In this implementation, the heat exchanger of the intermediate cooler, which realizes closed intermediate cooling, is continuously configured with the heat exchanger in the liquefier. For this purpose, the heat exchanger conduit passes either first through the intermediate cooling and further through a partition wall into the pressure region of the condenser stage. Alternatively, however, the return from the region to be heated can first be fed into the heat exchanger in the liquefier, from where it then passes into the heat exchanger in the intermediate cooler. Here, it is also preferred that the two heat exchangers, i.e. the heat exchanger for intermediate cooling and the heat exchanger in the liquefier, are configured as a single heat exchanger throughout, so to speak, in such a way that one conduit of this heat exchanger passes through the partition wall between the vapor space of the intermediate cooling area and the liquefier area of the liquefier. Alternatively, however, an implementation can be used in which the heat exchangers in the liquefier and in the intermediate cooler are connected to one another outside the heat pump volume, so that then no passage through the partition wall into the pressure region of the downstream stage is needed.

Preferred embodiments of the present invention will be explained in detail below with reference to the accompanying drawings. They show: Fig. 1a a preferred embodiment of a heat pump with closed intermediate cooling and connection to the return from the region to be heated; Fig. 2 an alternative embodiment of the present invention wherein the return from the region to be heated is first passed through the liquefier and then through the intermediate cooler; Fig. 3 an alternative embodiment of the present invention wherein the return from the region to be heated is first passed through the intermediate cooler and then through the liquefier heat exchanger; Fig. 4 an embodiment of the present invention wherein the heat exchanger in the intermediate cooler inside the heat pump is connected to the heat exchanger in the liquefier so that a conduit of the heat exchanger passes through the partition wall to the stage with higher pressure; Fig. 5 a schematic heat pump according to prior art; Fig. 6 a schematic illustration of a compressor stage with suction port, radial impeller and guide space; and Fig. 7 a tabular overview of different modes in which the heat pump can be operated.

Fig. 1 shows a heat pump with an evaporator 10, a liquefier 20 and a compressor 30. The compressor comprises a first compressor stage 31, a vapor space 32 and a second compressor stage 33. It should be noted that the present invention is not limited to the usage of only two stages, but may also include the usage of three, four, five, or even more stages. In any case, the vapor space 32, in which an intermediate cooler 40 is arranged, is arranged between at least two stages of the plurality of stages of the compressor engine.

In addition, the evaporator can be coupled to a region to be cooled 50 and the liquefier can be coupled to a region to be heated 60. The evaporator 10 is configured to evaporate operating liquid. Operating liquid is provided, for example, via a connection 11 for a return from the region to be cooled. This liquid provided via the connection 11 is warmer than the liquid output by the evaporator via a connection 12 to an inflow to the region to be cooled out of the evaporator. The heat introduced into the evaporator via the connection for the return is guided by the evaporated operating vapor via a suction line 13 into the first stage 31 of the compressor 30. The evaporated operating vapor is compressed in the first stage, and the compressed operating vapor enters the vapor space 32. The compressed operating vapor is cooled therein to reduce its typically occurring overheating. In the second compressor stage 33, the operating vapor, which has in the meantime been cooled by the intermediate cooler 40, is then compressed again and then introduced into the liquefier 20 via a discharge line 24, The liquefier includes a liquefier input 21 and a liquefier output 22. Above that, the intermediate cooler 40 comprises a heat exchanger comprising a heat exchanger input 41 and a heat exchanger output 42. According to the invention, the heat exchanger input 41 or the heat exchanger output 42 is connected to the liquefier input 21 or the liquefier output 22 in order to guide cooling liquid for the liquefier in a circuit through both the liquefier 20 and the heat exchanger in the intermediate cooler 40 during operation of the heat pump.

basically, the liquefier can be an open liquefier, so that the cooling liquid for the liquefier is the liquid into which the compressed operating vapor supplied by the discharge line 24 is condensed directly. Alternatively, the liquefier can be a closed liquefier, so that the liquefier also contains a heat exchanger with a conduit through which the cooling liquid for the liquefier flows, but has only thermal contact with the situation in liquefier 20, but no direct contact with the medium. Nevertheless, in both cases, the liquid fed into the liquefier via its input 21 serves as a cooling liquid for the liquefier, because by this liquid, regardless of whether it is used directly for condensation or whether it is separated from the operating vapor by a conduit, i.e. a closed conduit.

In the embodiment shown in Fig. 1, the heat pump has a connection 61 for connecting the inflow for the region to be heated 60. In addition, the heat pump also has a connection 62 for connecting the return from the region to be heated. The input 41 of the heat exchanger in the intermediate cooler is connected to the connection 62 for the return from the region to be heated. In addition, the output 42 of the heat exchanger is connected to the liquefier input 21. Furthermore, the liquefier output 22 is connected to the connection for the inflow to the region to be heated.

Fig. 1 further shows a heat exchanger 710 and a mixer or switch 720. The heat exchanger 710 and the mixer/switch 720 are optional. The switch can be controlled to bypass the heat exchanger 710 in position 1 and to integrate the heat exchanger 710 fully in position 2. It should be noted that the mixer/switch and the heat exchanger may also be present in the embodiments of the other Fig. 2a to 4, although it is not drawn in. On the "warm side" (1st side), the connection 62 of the region to be heated is connected to a first input of the heat exchanger, and the first output is connected to intermediate cooler input 41. On the "cold" side (2nd side), the 2nd input is connected to the output 2 of the heat exchanger and the 2nd output is connected to the input 11 of evaporator 10. The output 2 of switch 720 is also coupled to the second output.

Fig. 1 further shows an evaporator circuit interface 11, 12 for introducing liquid to be cooled into the heat pump and for discharging cooled liquid from the heat pump, a condenser circuit interface 21, 22 for introducing liquid to be heated into the heat pump and for discharging heated liquid from the heat pump, the condenser circuit interface being coupled to the intermediate cooler (40), a controllable heat exchanger which is implemented, e.g., as the combination of heat exchanger 710 and switch/mixer 720 for controllably coupling the evaporator circuit interface and the condenser circuit interface; and a control 730 for controlling the controllable heat exchanger (710, 720) depending on an evaporator circuit temperature (TV or TWK) in the evaporator circuit interface or a condenser circuit temperature (TK or TWW) in the condenser circuit interface.

Preferably, the heat exchanger 710 is connected between the intermediate cooler input 41 and the connection 62 for the region to be heated. Alternatively, the warm side of the mixer in Fig. 1 is connected between the intermediate cooler output 42 and the liquefier input 21. Alternatively, in the embodiment in Fig. 2, the warm side of the mixer is connected between the intermediate cooler output 42 and the connection 61 for the inflow to the region to be heated, or between the liquefier output 22 and the intermediate cooler input 41.

Preferably, the control 730 is configured to prevent cooling of the liquid to be cooled by the liquid to be heated using the controllable heat exchanger preferably consisting of the heat exchanger 710 and the mixer or switch 720, when a condenser circuit temperature of the liquid to be heated is higher than an evaporator circuit temperature of the liquid to be cooled, or to prevent cooling of the liquid to be cooled by the liquid to be heated using the controllable heat exchanger and, depending on a required cooling capacity, to perform speed control of a radial impeller of a compressor in the heat pump when a condenser circuit temperature of the liquid to be heated is higher than an evaporator circuit temperature of the liquid to be cooled, or to activate cooling of the liquid to be cooled by the liquid to be heated using the controllable heat exchanger, when a condenser circuit temperature of the liquid to be heated is iower than an evaporator circuit temperature of the liquid to be cooled, or to activate cooling of the liquid to be cooled by the liquid to be heated using the controllable heat exchanger and, depending on a required cooling capacity, to increase or decrease a speed of a radial impeller within the compressor of the heat pump device or to deactivate a compressor in the heat pump device, when a condenser circuit temperature of the liquid to be heated is lower than a predetermined temperature of the liquid to be cooled or the cooled liquid, or to throttle a circulation pump arranged in the condenser circuit interface with respect to a set speed when the condenser circuit temperature of the liquid to be heated is equal to or lower than a predetermined temperature of the liquid to be cooled or the cooled liquid.

Fig. 2 and Fig. 3 show an implementation where the heat exchanger 43 in the intermediate cooler 40 is shown in more detail as a continuous conduit. In addition, another heat exchanger 23 is also shown in the liquefier 20 as a closed heat exchanger, which ensures that the cooling liquid runs in the conduit of heat exchanger 23, but that this cooling liquid does not come into contact with the compressed operating vapor, i.e. not into direct contact via the vapor supplied from the line 24, but only into thermal contact with the vapor or with liquefied operating liquid present in the liquefier in order to discharge heat from the liquefier.

Fig. 3 shows an implementation similar to Fig. 1, namely that the cooling liquid supplied via the connection for the return 62 from the region to be heated 60 passes first through the heat exchanger 43 and then through the heat exchanger 23.

On the other hand, Fig. 2 shows an alternative implementation in which the return from the region to be heated 60 is first guided via the connection 62 for the return from the region to be heated into the heat exchanger 23 via its input 21, and then out of the heat exchanger 23 via its output 22 into the input 41 of the heat exchanger 43, which is arranged in the vapor space between the two compressor stages 31, and from there via the connection 61 into the region to be heated 60. It can be seen that in Fig. 2 the flow direction of the coolant, which is cooled in the region to be heated 60, is opposite to the flow direction of the cooling liquid in Fig. 3.

In particular, in the embodiment shown in Fig. 2, the input 41 of the heat exchanger is connected to liquefier return 22. In addition, the output 42 of the heat exchanger 23 of the intermediate cooler 40 is connected to a connection 61 for an inflow to the region to be heated. In addition, the liquefier input 21 of heat exchanger 23 of the liquefier is connected to the connection 62 for the return from the region to be heated 60.

As it has been shown, the liquefier can be an open liquefier where the compressed operating vapor condenses directly into the liquid which also runs in the heat exchanger 43 of the intermediate cooler 40. Alternatively, as shown in particular in Fig. 2 and Fig. 3 and also in Fig. 4, the liquefier input 21 and the liquefier output 22 are connected inside the liquefier by an intermediate conduit, so that a liquid in the conduit is separated from an operating liquid liquefied in the liquefier 20 regarding media, but is in thermal contact.

In the embodiment shown in Fig. 4, a wall 59 is arranged between the liquefier space, i.e. the space into which the discharge line 24 opens, and the vapor space 32. In the embodiment shown in Fig. 4, one conduit of the heat exchanger 43 of the intermediate cooler or one conduit of the heat exchanger in the liquefier passes through this wall 59 within the heat pump. Thereby, both the heat exchanger 43 in the intermediate cooler 40 and the heat exchanger 23 in the liquefier are directly coupled. Depending on the flow direction of the cooling liquid, either the liquefier output 22 or the liquefier input 21 is connected to the heat exchanger output 42 or the heat exchanger input 41. Therefore, in Fig. 4, the corresponding heat exchanger inputs/outputs are each provided with both reference numbers, because the definition of whether the input is an input or an output depends on the flow direction of the cooling liquid flows, i.e. whether the cooling liquid, which communicates with the heat pump from the region to be heated via connections 61, 62, flows either first in the intermediate cooler 40 or through the heat exchanger 43 in the intermediate cooler 40, as shown in Fig. 1 and in Fig. 3, or whether the liquid first flows through the heat exchanger 23 in the evaporator and only then passes through the intermediate cooler, as shown in Fig. 2 For this reason, the connections between the outputs of the heat exchanger cascade of heat exchangers 43 and 23 are shown as dashed lines in Fig. 4. However, it should be noted that typically only one of the two configurations is used in an actual heat pump implementation.

Above that, Fig. 4 shows a first throttle or first expansion valve 61 between the vapor space 32 of the intermediate cooler and the evaporator 10. Above that, a second throttle is schematically shown, which is also shown as an expansion valve at 62 by which the liquefier space of liquefier 20 is connected to the evaporator 10 to obtain return of operating liquid to ensure the complete circuit.

In addition, Fig. 4 at 71 shows a droplet separator arranged between the evaporator 10 and the first compressor stage 31. In addition, a further droplet separator 72 is optionally provided, which is arranged in the vapor space between the first compressor engine 31 and the second compressor engine 33. In addition, a control is shown in Fig. 4 at 80, by which the two-stage compressor can be controlled to run the heat pump in single-stage operation when the requirements are not so high, and to run the heat pump in two-stage operation when the requirements are high.

Fig. 6 shows a schematic illustration of an engine of a compressor stage 31 or 33. In particular, Fig. 6 shows a compressor stage with a suction port 91, a radial impeller 92, an engine 93 and a guide space 94 to compress vapor. When the radial compressor or turbo compressor of Fig. 6 is used in the first stage 31, the vapor sucked in via the suction port 91 comes from the evaporator and the vapor discharged via the guide space 94 runs into the vapor space 32. If, on the other hand, the turbo compressor shown in Fig. 6 is used in the second compressor stage 31, the vapor sucked in via the suction port runs out of the evaporator and has been cooled by the intermediate cooler 40, and if the vapor discharged from the guide space 94, is the vapor which is finally fed into the liquefier 20 and liquefied there to release its energy to the liquefier and finally to the cooling liquid, which can run via the liquefier output 22 into the region 60 to be heated.

According to the invention, a large part of the overheating enthalpy has thus already been discharged to the cooling water system as heating capacity, i.e. to the circuit that runs through the region to be heated 60. If the heat exchanger 43 in the vapor space is configured slightly larger than actually needed for intermediate cooling, single-stage operation can already take place via this heat exchanger 43. There is no need to switch between single-stage and multi-stage operation. This means that there is no need to switch liquid conduits between the two operating modes. In the single-stage case, the compressor of the downstream stage is simply switched off. Only the first compressor 31 and a pump, which is shown at 82 and can be arranged anywhere in the cooling circuit, but preferably at the externally accessible connection of the heat exchanger 23 in the liquefier, are necessary in single-stage operation. This is shown in the top left of Fig. 4. In two-stage operation, however, both compressors K1, K2 and also pump P are switched on.

It should be noted that in certain embodiments, condensation takes place at the heat exchanger 43 in single-stage operation. It is therefore preferable to provide a throttle 63 to bring this condensate into the evaporator. In addition, the second throttle 62 is provided to provide for a closed system in two-stage operation. This means that the system has an open component, since in single-stage operation the condensate is to be fed to throttle 63 via an area and is to be collected first.

The cooling liquid and the condensate of the downstream stage are returned to the evaporator via throttle 64, where the circuit is closed. It is preferred that the water in the second throttle 62 does not touch the heat exchanger 43, as it would otherwise cool the cooling water in the heat exchanger by evaporation. Instead of the throttle 64 or in addition, there may be a further throttle 65 (marked with a dotted line in Fig. 4) between the liquefier 20 and the vapor space 32, which is supplemented by the throttle 63 between the vapor space 32 and the evaporator 10. The throttles are configured in such a way that the intermediate cooler 40 in vapor space 32 does not come into contact with liquid from the throttles.

If, as shown, for example, in Fig. 2, the cooling water first flows through the downstream stage, i.e. through the liquefier, and then through the intermediate cooling of the first stage, the temperature of the same increases and with it the distance to the saturated vapor temperature in the intermediate cooling. In single-stage operation, however, the condensation space after the stage can also be partially used, and thus the heat exchange surface in the intermediate cooling and single-stage operation can again be somewhat reduced.

Depending on the implementation, the droplet separator 72 can also be omitted, as the heat exchanger 43 provides for slight overheating. This means that no drops are produced in this area when the second stage inactive. However, the start-up of the second stage is critical if the water vapor has previously condensed in the intermediate cooling and the same is moist at start-up. Then, water droplets can be created by lowering the suction pressure due to boiling and the droplet separator 72 is necessary at least for a short time, this can be avoided by starting the second stage slowly.

Fig. 7 shows a tabular compilation of different modes, which can be effected e.g. with a two-way switch 720 and the heat exchanger 710, as shown in Fig. 1.

Especially in a cold temperature range where a sample air temperature is less than 10 °C and where the sensor values are such that the TWK (temperature at or in the region to be cooled 50) is greater than TWW (temperature at or in the region to be heated 60), free cooling is active. Furthermore, the controllable heat exchanger is flowed through from both sides, i.e. it is active. Furthermore, the compressor (both stages) is deactivated, i.e. switched off. Temperature control can be achieved, for example, by controlling the liquefier-side pump contained in a condenser circuit interface. If it is determined that the temperature of the cooled liquid becomes lower than a set temperature, the pump can be throttled. If, on the other hand, it is found that the temperature is getting too high, the pump can be turned faster again. Alternatively or additionally, a fan typically present in the region to be heated 60 can be turned faster or slower to achieve more or less cooling capacity.

Free cooling is also active in a medium cold temperature range, for example between 10 °C and 16 °C. In addition, the compressor is also active in a first stage, and possibly in the second stage, and a regulation of the temperature, which is fed into the data center, or into the region to be cooled, can be carried out by controlling the speed of the radial impeller in the first stage of the compressor, switching on the second stage, and/or controlling the speed of the radial impeller in the second stage. If a higher cooling capacity is required, the speed is increased and/or the second stage is switched on. If, on the other hand, less cooling capacity is required, the speed of the radial impeller is reduced and/or the second stage is switched off.

In normal operating mode, which is activated in a warm temperature range, the temperatures are, for example, higher than 16 °C. Then, the controllable heat exchanger is deactivated, i.e. switched to inactive, and cooling capacity can again be controlled via the speed of the radial impeller. However, in this mode, i.e. in the warm temperature range, no free cooling is active.

As a special mode, a controllable short-circuit can be achieved between the output or condenser circuit and the input or evaporator circuit of the heat pump device. Particularly with high outside temperatures on the one hand and relatively low performance requirements of the computer center, because there is only partial load operation, for example, the situation can arise there that the control would switch to on-off cycling without the special mode with controllable short circuit, which is not advantageous for various reasons.

According to the invention, the special mode with controllable short-circuit is therefore activated, which is detected, for example, by a certain clocking frequency. If too high a clocking frequency is determined, the controllable short-circuit is activated, i.e. a typically smaller portion, i.e. a portion less than 50 % of the flow rate, is fed into the corresponding first or second path of the heat exchanger unit and recombined with the other (typically larger) portion at the output of the heat exchanger unit. This mixer effect can be controlled, if necessary, as shown in Fig. 7 in the last line of the table, depending on the implementation, e.g. from a 1%/99% control to a 51%/49% control. In any case, it is preferred that the greater part of the flow bypasses the heat exchanger element 710 and only the smaller part of the flow passes through the heat exchanger element 710, whereby, as already mentioned, the portion of the smaller flow is controllable from 0 to 50%, depending on the configuration of the mixer.

Therefore, in the case of preferred embodiments of Free Cooling Plus, a heat exchanger and a three point switch are installed. The three-point switch can be installed on the cold water side or the hot water side and is intended to enable or block the flow through the heat exchanger. Due to its poor volumetric cooling capacity, water as a coolant offers the advantage for free cooling Plus, that the volume flow and pressure ratio can be adjusted by means of a speed-controlled radial compressor, resulting in an almost ideal operating point for the system in a wide range of applications, wherein this can be achieved already at low cooling capacities below 50 kW. In the implementations shown, water is cooled from e.g. 20°C to 16°C, although other temperatures are also possible, such as cooling to 20°C from a higher temperature of 26°C. In general, it is always obtained that the cooling capacity is brought to a temperature level with the lowest possible energy input in order to discharge the capacity to the environment again, depending on the outside temperature. If a temperature is supplied from the roof, i.e. the region to be heated (recooler), which allows the entire cooling capacity to be transferred from the cold water to the cooling water by the upstream heat exchanger, no compressor work is performed. If the ambient temperatures continue to rise, so that no 20 °C cold water is produced without compressor work, the compression cooling system is switched on at a capacity-controlled rate to provide the missing part, for example 3 °C or 50 % capacity. If the outside temperatures continue to rise and the cooling water reaches temperatures of 25 °C and more, for example, practically no more energy can be transferred through the heat exchanger. The entire cooling capacity must now be provided by the compression refrigeration machine, If the cooling water temperatures continue to rise, in this area above 26 °C, the three-way switch must block the flow through the heat exchanger on at least one side, otherwise the refrigeration system would have to provide even more cooling capacity than required by the application.

In specific alternative embodiments, it is preferred that the control, i.e. whether the heat exchanger is flown through or not, depends merely on the temperatures TWW and TWK; namely, if the temperature TWW is lower than TWK, the heat exchanger unit is flown through. If the temperature in the evaporator is higher than the inlet temperature on the cold water side or customer side, the compressor must operate. If, on the other hand, the temperatures in the free cooling mode are below the required customer temperature, in this case 16 °C, the fan on the roof and finally the pumps can be throttled.

REFERENCE NUMBERS LIST

evaporator 11 connection for return from the region to be cooled 12 connection for inflow to the region to be cooled 13 suction line liquefier 21 liquefier input 22 liquefier output 23 heat exchanger in the liquefier 24 discharge line compressor 31 first compressor stage 32 vapor space 33 second compressor stage intermediate cooler 41 intermediate cooler input 42 intermediate cooler output 43 heat exchanger in the intermediate cooler 50 region to be cooled 59 partition wall region to be heated 61 connection for inflow to the region to be heated 62 connection for return from the region to be heated 63 first throttle 64 second throttle further throttle 71 droplet separator 72 droplet separator 80 control 82 pump 91 suction port 92 radial impeller 93 engine 94 guide space evaporator 102 heat exchanger compressor 112 suction line 114 discharge line 120 liquefier 122 heat exchanger expansion valve 710 Heat exchanger unit 720 Two-way switch

Claims

Claims 1. Heat pump, comprising: an evaporator (10) for evaporating operating liquid; a liquefier (20) for liquefying compressed operating vapor; a compressor (30) with a first compressor stage (31), a second compressor stage (33) and a vapor space (32) between the first compressor stage (31) and the second compressor stage (33); an intermediate cooler (40) with a heat exchanger (43) arranged in the vapor space (32) and comprising a heat exchanger input (41) and a heat exchanger output (42), the heat exchanger input (41) or the heat exchanger output (42) being connected to a liquefier input (21) or a liquefier output (22) in order to guide cooling liquid for the liquefier (20) in a circuit through both the liquefier (20) and the heat exchanger (43) during operation of the heat pump.
Heat pump according to claim 1, wherein the heat exchanger input (41) is connected to a connection (62) for a return from a region to be heated (60), wherein the heat exchanger output (42) is connected to the liquefier input (21), and wherein the liquefier output (22) is connected to a connection (61) for an inflow to the region to be heated (60).
3. Heat pump according to claim 1, wherein the heat exchanger input (41) is connected to the liquefier output (22), wherein the exchanger output (42) is connected to a connection (61) for an inflow to the region to be heated (60), and wherein the liquefier input (21) is connected to a connection (62) for a return from the region to be heated (60).
4. Heat pump according to one of the preceding claims, wherein the liquefier (20) is an open liquefier, wherein the compressed operating vapor condenses directly into a liquid which passes through the heat exchanger (43) of the intermediate cooler during operation of the heat pump.
Heat pump according to one of claims 1 to 3, wherein the liquefier input (21) and the liquefier output (22) are connected to one another by an intermediate conduit, such that a liquid in the conduit is separated from an operating liquid liquefied in the liquefier (20).
6. Heat pump according to claim 5, wherein heat exchanger (43) comprises a heat exchanger conduit, wherein a liquefier conduit is arranged between the liquefier input (21) and the liquefier output (22), wherein a partition wall (59) is arranged between the vapor space (32) and the liquefier (20), and wherein the heat exchanger conduit or the liquefier conduit passes through the partition wall (59).
Heat pump according to one of the preceding claims, further comprising a pump (82) connected to a connection (61) for the inflow to the region to be heated (60) or to a connection (62) for the return to the region to be heated (60).
8. Heat pump according to one of the preceding claims, further comprising a control that is configured to operate the heat pump in a single-stage or in a two-stage operation depending on a parameter, wherein in the single-stage operation the second compressor stage (33) is switched off and the first compressor stage (31) is switched on, and wherein in the single-stage operation the heat exchanger (43) of the intermediate cooling (44) comprises a condenser.
9. Heat pump according to claim 8, wherein the pump (82) is active in both the single-stage operation and the two-stage operation in order to circulate the cooling liquid through both the heat exchanger of the intermediate cooler (40) and the liquefier (20).
10. Heat pump according to one of the preceding claims, further comprising a throttle (63) between the vapor space (32) and the evaporator (10) or a throttle (64) between the liquefier (20) and the evaporator (10), or comprising a throttle (65) between the liquefier (20) and the vapor space (32) and a throttle (63) between the vapor space (32) and the evaporator (10), the throttles being configured such that the intermediate cooler (40) in the vapor space (32) does not come into contact with liquid from the throttles.
11. Heat pump according to claim 10, wherein the throttle between the liquefier (20) and the evaporator (10) comprises a conduit that prevents contact of the liquid in the throttle with the heat exchanger (43).
12. Heat pump according to one of the preceding claims, wherein a droplet separator (71) is arranged between the evaporator (10) and the first compressor stage.
13. Heat pump according to one of the preceding claims, wherein a droplet separator (72) is arranged between the intermediate cooler (40) in the vapor space (32) and the second compressor stage (33).
14. Heat pump according to one of the preceding claims, wherein the first compressor stage (31) or the second compressor stage (33) comprises: a suction port (91); an engine (93) coupled to a radial impeller (92), wherein the engine is configured to suck liquid vapor via the suction port (91) by rotating the radial impeller (92); and a guide space (94) for guiding sucked operating vapor into the vapor space (32) or the liquefier (20).
15. Heat pump according to one of the preceding claims, further comprising: a cooling heat exchanger that can be mounted in the region to be cooled (50) and is connected to the evaporator (10); and a waste heat heat exchanger that can be mounted in the region to be heated (60) and is coupled to the intermediate cooler (40) and the liquefier.
16. Heat pump according to one of the preceding claims, further comprising: an evaporator circuit interface for introducing liquid to be cooled into the heat pump and for discharging cooled liquid from the heat pump; a condenser circuit interface for introducing liquid to be heated into the heat pump and for discharging heated liquid from the heat pump, the condenser circuit interface being coupled to the intermediate cooler (40); a controllable heat exchanger (710, 720) for controllably coupling the evaporator circuit interface and the condenser circuit interface; and a control (730) for controlling the controllable heat exchanger (710, 720) depending on an evaporator circuit temperature in the evaporator circuit interface or a condenser circuit temperature in the condenser circuit interface (300).
17. Heat pump according to one of the preceding claims, wherein the control (730) is configured to prevent cooling of the liquid to be cooled by the liquid to be heated using the controllable heat exchanger (700) when a condenser circuit temperature of the liquid to be heated is higher than an evaporator circuit temperature of the liquid to be cooled or to prevent cooling of the liquid to be cooled by the liquid to be heated using the controllable heat exchanger and to carry out speed control of a radial impeller of a compressor in the heat pump depending on a required cooling capacity when a condenser circuit temperature of the liquid to be heated is higher than an evaporator circuit temperature of the liquid to be cooled or to activate cooling of the liquid to be cooled by the liquid to be heated using the controllable heat exchanger when a condenser circuit temperature of the liquid to be heated is lower than an evaporator circuit temperature of the liquid to be cooled or to activate cooling of the liquid to be cooled by the liquid to be heated using the controllable heat exchanger and, depending on a required cooling capacity, to increase or decrease a speed of a radial impeller within the compressor of the heat pump device or to deactivate a compressor in the heat pump device when a condenser circuit temperature of the liquid to be heated is lower than a predetermined temperature of the liquid to be cooled or the cooled liquid or to throttle a circulation pump disposed in the condenser circuit interface with respect to a set speed when the condenser circuit temperature of the liquid to be heated is equal to or lower than a predetermined temperature of the liquid to be cooled or the cooled liquid.
18. Method for pumping heat with a heat pump comprising: an evaporator (10) for evaporating operating liquid; a liquefier (20) for liquefying compressed operating vapor; a compressor (30) with a first compressor stage (31), a second compressor stage (33) and a vapor space (32) betWeen the first compressor stage (31) and the second compressor stage (33); an intermediate cooler (40) with a heat exchanger (43) arranged in the vapor space (32) and comprising a heat exchanger input (41) and a heat exchanger output (42), the heat exchanger input (41) or the heat exchanger output (42) being connected to a liquefier input (21) or a liquefier output (22), the method comprising the step of guiding cooling liquid for the liquefier (20) in a circuit through both the liquefier (20) and the heat exchanger (43).
19. Method for producing a heat pump comprising an evaporator (10) for evaporating operating liquid; a liquefier (20) for liquefying compressed operating vapor; a compressor (30) with a first compressor stage (31), a second compressor stage (33) and a vapor space (32) between the first compressor stage (31) and the second compressor stage (33); and an intermediate cooler (40) with a heat exchanger (43) arranged in the vapor space (32) and comprising a heat exchanger input (41) and a heat exchanger output (42), comprising the step of: connecting the heat exchanger input (41) or the heat exchanger output (42) to a liquefier input (21) or a liquefier output (22) in order to guide cooling liquid for the liquefier (20) in a circuit through both the liquefier (20) and the heat exchanger (43) during operation of the heat pump.