Cooling system and experimental device comprising cooling system

Abstract

To provide a cooling system capable of being used to cool or temperature-control a device.SOLUTION: The present application relates to a cooling system (10). The cooling system (10) has an evaporator (11), a first compressor (12), a second compressor (14), a cooling component (16), an expansion device (18), and piping systems (20', 21') connecting the evaporator (11), the first compressor (12), the second compressor (14), the cooling component (14) and the expansion device (18) together. The cooling system (10) contains a refrigerant, where the refrigerant is carbon dioxide. The first compressor (12) and the second compressor (14) are arranged in series with each other. The present application also relates to a corresponding experimental device (300).SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to a cooling system that can be used to cool or temperature regulate equipment. In particular, the present invention relates to a cooling system for use with laboratory equipment. Furthermore, the present invention relates to laboratory equipment including, among others, centrifuges, incubators, and biological safety cabinets. [Background technology]

[0002] It is known to cool laboratory equipment, such as for example a centrifuge, by means of a cooling system or to regulate the temperature of laboratory equipment (for example a centrifuge). A corresponding cooling system usually comprises an evaporator, a compressor, a cooling component and an expansion device, which are connected to each other in a circuit via a piping system. Such a cooling system works with a refrigerant, which changes state in a circulation system, thereby removing heat from the surroundings at a process point (typically the evaporator) and releasing heat to the surroundings at another process point (typically the cooling component). That is, in the cooling component, heat is removed from the refrigerant in the system, i.e. the refrigerant is cooled (for example by a ventilator, etc.).

[0003] Although cooling systems, especially for laboratory equipment, have been well documented in the prior art, they suffer from several inadequacies or shortcomings, for example related to safety, environmental compatibility, and ease of use, as well as the scope of application of the cooling systems. Summary of the Invention [Problem to be solved by the invention]

[0004] The object of the present invention is to overcome or at least mitigate the inadequacies or shortcomings of the prior art. It is therefore an object of the present invention to provide a cooling system, for example for laboratory equipment, which is improved in particular with respect to at least one of the following aspects: safety, environmental compatibility, ease of use, and breadth of application range. In particular, the cooling system is improved with respect to several of these aspects. [Means for solving the problem]

[0005] The above problems are solved by the cooling system of the present invention.

[0006] According to a first aspect, the present invention relates to a cooling system, the cooling system comprising an evaporator, a first compressor, a second compressor, a cooling component, an expansion device, and a piping system. The piping system interconnects the evaporator, the first compressor, the second compressor, the cooling component, and the expansion device. The cooling system contains a refrigerant, the refrigerant being carbon dioxide. The first compressor and the second compressor are arranged in series with each other.

[0007] The cooling system may absorb heat in an evaporator and release heat in a cooling component. The cooling system may in particular comprise a closed refrigerant circuit, whereby the refrigerant circulates in the cooling system without any physically coupled exchange with the surrounding atmosphere and / or a secondary refrigerant circuit. The cooling component may be a heat exchanger configured to thermally couple the refrigerant to the surrounding atmosphere in order to achieve efficient cooling of the refrigerant. The refrigerant may be in gaseous form in the cooling component. Furthermore, the cooling component may be a condenser configured to transition the refrigerant to a liquid state.

[0008] By using two compressors, the cooling system is made multi-stage. This has the advantage that particularly high pressures can be achieved or that high pressures can be achieved as energy-efficiently as possible. The refrigerant can be compressed successively from a first pressure through at least one intermediate pressure to a final pressure. For each intermediate compression, a separate compressor can be provided. This allows the compression process to be distributed over several compressors.

[0009] The expansion device can in particular be configured as an expansion valve. In order to achieve a controllable pressure regulation, in particular a pressure drop, the expansion valve can be controllably configured. The expansion valve allows the refrigerant to expand.

[0010] The cooling component may be arranged downstream of the compressor and / or a further compressor in the direction of refrigerant flow.

[0011] The refrigerant is carbon dioxide (hereinafter also abbreviated as CO2 or R744). R744 can have low toxicity. Therefore, CO2 is particularly an alternative to ammonia. When using R744, the refrigeration system can perform a supercritical cycle. The critical point can be exceeded. Thereby, the pressure and / or temperature in the compressor can be increased.

[0012] The use of CO2 as a refrigerant allows for a lower Global Warming Potential (GWP) compared to conventional refrigerants. If the GWP is limited to less than 150, possible refrigerants can be flammable (e.g. A3 and A2L class refrigerants) or non-flammable CO2 can be used. By using CO2, operating pressures up to 140 bar can be achieved. In particular, higher operating pressures, e.g. pressures above 60 bar, can be achieved compared to the use of flammable refrigerants and / or fluorinated and / or halogenated hydrofluorocarbons.

[0013] The use of CO2 as a refrigerant differs from various prior art cooling systems that use flammable refrigerants or hydrocarbons in which at least one hydrogen has been replaced by a halogen (such as the so-called fluorinated and halogenated hydrofluorocarbons or F gases) as refrigerants. CO2 has the advantage of being more reliable in operation compared to flammable refrigerants, and more importantly, CO2 has the advantage of being more environmentally friendly compared to other refrigerants.

[0014] When using CO2 as a refrigerant, the maximum achievable high pressure of a single stage compression with one compressor may be limited. This drawback is overcome by the present invention using two-stage compression, which on the other hand also makes it possible to use a relatively simply designed compressor.

[0015] With regard to the use of cooling systems in laboratory equipment, in particular centrifuges, the permissible ambient temperature for the operation of the laboratory equipment may be up to 40°C. At this temperature, CO2 as a cooling medium may already be in gaseous form in the cooling system. The CO2 may be cooled by heat exchange with the surrounding atmosphere. In this case, the CO2 may remain in gaseous form. Thus, high pressures of at least 60 bar, preferably at least 70 bar, may be achieved in the cooling system. The corresponding compression may be achieved by two-stage compression.

[0016] Thus, generally, embodiments of the present invention provide a new cooling system for efficient use of CO2 as a refrigerant.

[0017] The refrigeration system may be configured to perform a supercritical vapor compression cycle, in which the refrigerant may exceed the critical point of the primary refrigerant, at least temporarily, or for a portion of the cycle. In particular, one portion of the cycle may be performed at a pressure above the critical point, and another portion of the cycle may be performed at a pressure below the critical point. The critical point may indicate an upper limit for heat transfer processes based on evaporation or condensation. At temperatures and pressures above this critical point, it is no longer possible to clearly distinguish between liquid and vapor. All refrigerants have a critical point, but conventional refrigerants may always be below this point in a typical refrigerant circuit.

[0018] The refrigerant circuit may have certain cycle performance characteristics corresponding to a preferred operating state-point where the cooling system operates with optimal cycle efficiency. The cooling system may achieve the advantage that if it deviates from this operating state-point it can be re-controlled accordingly to achieve optimal system efficiency. In this case the control comprises in particular a local adaptation of the refrigerant temperature by internal heat transfer or a secondary refrigerant flow. Internal heat transfer may be defined as the conduction of heat from a first cooling system section to a second cooling system section by thermal coupling of these cooling system sections. A secondary refrigerant flow may be realised by an additional piping section which diverts the refrigerant from the main circuit and returns it to the main circuit at another point. This may realise heat transfer by material coupling.

[0019] By arranging the first compressor and the second compressor in series, the refrigerant compressed to an intermediate pressure is fed to the second compressor, which compresses the refrigerant from the intermediate pressure to the high pressure. Accordingly, the first compressor can be optimized for the first compression from low pressure to the intermediate pressure and the second compressor for the compression from the intermediate pressure to the high pressure. Correspondingly, each compression stage can be realized with a high efficiency. Advantageously, the first compressor and / or the second compressor can be formed as a totally hermetic compressor that prevents the flow of the refrigerant to the surrounding atmosphere.

[0020] The embodiments of the present invention allow the temperature of the cooling medium in various cooling system regions to be adjusted to their respective optimum values ​​by selective heat transfer within the cooling system. Furthermore, the compression process by two-stage compression can be achieved process-efficiently and cost-efficiently. For example, the final temperature of the hot gas can be reduced. Furthermore, the adjustment of the refrigerant temperature can be achieved without the use of a fluidically separated secondary refrigerant circuit. For this purpose, for example, a mixture of refrigerants from various process points of the refrigerant circuit can be utilized. Thus, advantageously, the temperature adjustment of the refrigerant by an external device can be omitted.

[0021] The invention can increase the crash safety of the laboratory equipment, and therefore achieve an improvement in system safety. In particular, by reducing to a single-circuit system, i.e. only one refrigerant conveying circuit is provided, the use of other refrigerants, in particular flammable or toxic refrigerants (propane - R290, ammonia - R717), can be avoided. A non-flammable refrigerant can increase the safety of the device. The rotor of the centrifuge can penetrate the tank wall and thus the evaporator tubes that conduct the refrigerant. In this case, the escaping CO2 can be classified as a low safety risk compared to flammable or toxic refrigerants.

[0022] Due to the high operating pressure, CO2 has a high density when evaporated and a high volumetric cooling capacity when heat is released, which allows the advantage of reduced installation space, especially when the cooling system is integrated in the centrifuge, e.g. the installation space volume of the cooling components or the condenser and / or the evaporator can be reduced.

[0023] Advantageously, the efficiency of the cooling system can be increased. The pressure ratio between the low pressure and the high pressure of the refrigerant can be limited. Furthermore, the pressure ratio can be increased by two-stage compression, which increases the possible operating range, in particular without heat radiation to the outside due to a secondary circuit. The operating range can be determined in relation to a specific ambient temperature range for the operation of the laboratory equipment. In addition, the cooling system, in terms of a cooling system with a secondary circuit (using a cascade process and / or a heat pump), can reduce the complexity of the equipment, thereby reducing the occurrence of malfunctions and / or reducing the maintenance effort.

[0024] The cooling component may include a gas cooler and / or a condenser. A gas cooler may provide the refrigerant in a gaseous state and at a reduced temperature at the outlet of the cooling component. A condenser may provide the refrigerant in a liquid state and at a reduced temperature at the outlet of the cooling component.

[0025] The refrigeration system can be configured to perform a supercritical vapor compression cycle, whereby pressures and temperatures above their respective critical values ​​can be achieved, for example by a second compressor in a second compression stage.

[0026] Additionally, the cooling component may be configured to transition the refrigerant from a gas phase to a liquid phase. Advantageously, the cooling component is also configured to withstand pressures and temperatures above critical points.

[0027] The cooling system can be configured to perform a subcritical vapor compression cycle. The pressure and temperature, especially of the second compressor, can also be adjusted accordingly in some operating conditions so as not to reach or exceed the critical point of CO2. By designing for the subcritical range, lower requirements can be used in terms of the permissible pressure and / or temperature, and accordingly components can be used that meet the lower requirements and would not be suitable for example for supercritical operation. This allows cost savings to be achieved.

[0028] The cooling systems can have cooling capacities of 10 W to 100 kW, in particular 500 W to 10 kW. Accordingly, the cooling circuits can be scaled from small mobile devices and laboratory bench-top equipment to large industrial installations.

[0029] The refrigeration system may have a main circuit including an evaporator, a first compressor, a second compressor, a refrigeration component, an expansion device, and at least a portion of a piping system. Additionally, a refrigerant may be present in the main circuit. A majority of the refrigerant flows through the main circuit. This may be defined as a refrigerant flow that includes more than 50% Gew (weight percent) of the refrigerant that is entirely present in the refrigeration system. A secondary piping section may be provided that includes a correspondingly smaller portion of the refrigerant. In particular, the refrigerant may be routed through the secondary piping section for internal temperature conditioning.

[0030] A cooling component can be disposed downstream of the second compressor and upstream of the expansion device. Accordingly, the cooling component can reduce the temperature of the refrigerant before it is fed to the expansion device. The cooling component can be formed as a heat sink and can remove heat from the refrigerant and reject it to the surrounding atmosphere or to an external cooling system.

[0031] The cooling component can be set to cool the refrigerant downstream of the second compressor, so that the refrigerant flows into the cooling component at the cycle point where the refrigerant temperature is at its maximum. The cooling component can reduce the enthalpy by lowering the refrigerant temperature. This process can be performed isobarically. Advantageously, cooling to temperatures below 30° C., preferably below 31° C., can be achieved.

[0032] The cooling system can be set up in such a way that if the refrigerant leaves the first compressor at the outlet temperature, it is fed to the second compressor at an inlet temperature lower than the outlet temperature. This allows the maximum temperature of the refrigerant at the second compressor or at the outlet of the second compressor to be reduced, and thus the thermal load of the second compressor to be reduced. By reducing the temperature between the compressors, the enthalpy can again be reduced isobarically.

[0033] The inlet and outlet temperatures may differ by a temperature difference of more than 1 K, preferably more than 2 K, more preferably more than 3 K. For example, the temperature difference may be in the range of 3 K to 8 K. Between the compressors, a heat sink may be provided which removes heat from the refrigerant and carries it away from the cooling system. In this case, for example, heat transfer to a central cooling plant and / or to the surrounding atmosphere may be realized.

[0034] The first and / or second compressor can be configured as scroll compressors, reciprocating compressors, screw compressors, rotary piston compressors or combinations thereof, whereby a compressor type optimized for the respective pressure range can be used, in particular a compressor type different from that of the second compressor can be used as the first compressor.

[0035] The cooling system may have a return section fluidly connected with the main circuit at the first and second connection points. The second junction may be located in the main circuit downstream of the first compressor and upstream of the second compressor. Via the return section, in particular the efficiency of the cooling system may be increased. The volumetric efficiency of the cooling system may be increased, so that the hot gas temperature at the outlet of the second compressor is reduced. The cooling capacity may be scaled to the volumetric efficiency of the cooling system. The volumetric efficiency may be the volumetric efficiency of the compressor capacity or of the compressor's actual discharge. High hot gas temperatures may affect, in particular reduce, the durability of the machine oil for lubricating the components. Thus, by reducing the temperature, the durability of the components may be prolonged.

[0036] Via the return section, refrigerant can be injected into the refrigerant flow in the main circuit before the inlet of the second compressor. The injected refrigerant can have a reduced temperature, in particular a lower temperature than the refrigerant in the main circuit at the injection point, here in particular at the second connection point. By mixing the refrigerants at the injection point of the second compressor, a mixed flow with reduced temperature can thus be provided.

[0037] The thermal load of the centrifuge can be dynamic, i.e. the evaporation temperature can change during operation. In this case, different thermal loads can occur depending on the respective operating mode of the centrifuge. For example, different rotors can be used and adjusted to different target speeds and / or target temperatures. By variable after-injection, the hot gas temperature at the compressor outlet or at the outlet of the second compressor can be adjusted to take into account the variable load of the evaporator.

[0038] The cooling system can be set up such that the refrigerant in the return section at the second connection has a lower specific enthalpy than the refrigerant immediately upstream of the second connection in the main circuit. In particular, the enthalpy of the return section can be increased substantially isobarically and / or substantially isothermally. By varying the enthalpy, the vapor content can be varied. Here, the vapor content can be selected such that the formation of liquid droplets is prevented in order to protect the compressor. For example, a vapor with a low liquid fraction can be introduced. In other words, the injection amount can be selected such that the enthalpy inflow allows to achieve a high vapor content.

[0039] The cooling system may include a heat exchanger having a primary side disposed downstream of the cooling component in the main circuit. The heat exchanger may be configured to cool a refrigerant in the main circuit.

[0040] In order to improve the cooling capacity when using CO2 as the refrigerant, an additional cooling of the refrigerant can be realized. Advantageously, the heat exchanger is configured to remove heat from the refrigerant downstream of the cooling component, more preferably at the outlet of the cooling component.

[0041] Heat exchangers can be used for energy optimization of cooling systems. Cooling systems can be used in equipment for analyzing medical samples, in particular in centrifuges, which can be operated up to an ambient temperature of 40°C. Depending on the temperature, the optimum high pressure can also be increased. The optimum high pressure can depend on the coefficient of performance. If the temperature and pressure values ​​exceed the critical point of the refrigerant, the heat release process can be carried out supercritically as gas cooling. Supercritical gas cooling can be carried out isobarically. In contrast, liquefaction can be carried out isobarically and largely isothermally. The pressure increase of supercritical gas cooling allows the driving force of the compressor to be increased.

[0042] The heat exchanger can be configured to bring the refrigerant to a predetermined temperature below an initial temperature of the cooling component at the first connection point and / or the piping section. The piping section can be defined by the first connection point and the inlet of the expansion device. The heat exchanger can remove heat from the refrigerant in the main circuit at constant pressure. The refrigerant can pass through the heat exchanger in a supercritical, gaseous or liquid state.

[0043] A heat exchanger may be located upstream of the expansion device in the main circuit, whereby the heat exchanger may contribute to cooling the refrigerant before it enters the expansion device.

[0044] The heat exchanger may include a secondary side arranged in the return section. Furthermore, the heat exchanger may be configured to absorb heat from the refrigerant by the primary side and release the absorbed heat to the refrigerant by the secondary side to heat the refrigerant in the return section. Due to the heating of the refrigerant in the return section, the refrigerant flow in the direction of the second connection point may still have a lower temperature than the refrigerant flow in the main circuit, in particular the refrigerant flow from the first compressor to the second compressor. By arranging another heat exchanger between the compressors and before the second connection point, the temperature of the main circuit at the second connection point may always be higher than the temperature of the refrigerant flow from the return section to the second connection point.

[0045] The refrigerant temperature between the outlet of the primary side of the heat exchanger and the inlet of the secondary side of the heat exchanger can be substantially the same. Here, heat losses occur through piping and / or other components, which can result in a small temperature difference. The secondary side can increase the enthalpy of the return section isobarically and / or isothermally. In this case, the refrigerant can be in a wet vapor phase. In the return section, the refrigerant can transition from the wet vapor phase to the gas phase at the second connection point. This can be achieved in particular by mixing at the connection point.

[0046] The secondary side can be arranged upstream of the second connection point in the return section. A partial coolant flow can accordingly flow from the first connection point through the secondary side to the second connection point. The heat transfer in the heat exchanger can be substantially internal, i.e. the heat can be transferred here from the main circuit flow to the return section flow. The heat flow and the material flow can be regulated separately.

[0047] The first compressor can be configured to compress the refrigerant from a first pressure range to a second pressure range, the second pressure range having a higher pressure than the first pressure range. Three pressure stages can then be distinguished: a low pressure, in particular upstream of the first compressor, an intermediate pressure, in particular downstream of the first compressor and upstream of the second compressor, and a high pressure, in particular downstream of the second compressor. The temperature of the refrigerant, in particular the enthalpy, can vary between the compression stages. In particular, the first compressor can be used to adjust the intermediate pressure for further compression by the second compressor. In addition, between the first and second compressors, an optimal or at least sufficiently low refrigerant temperature for the second compressor can be adjusted. The refrigerant temperature between the compressors can be achieved by mixing of the refrigerant via the return section and / or by active cooling using a heat sink.

[0048] The second compressor can be configured to compress the refrigerant from a secondary pressure range to a tertiary pressure range, the tertiary pressure range having a higher pressure than the secondary pressure range. In this case, the pressure difference achieved by the first compressor can be smaller than the pressure difference achieved by the second compressor. In particular, the second compressor can be configured for a higher inlet pressure than the first compressor. Correspondingly, a compressor capacity or a compressor type suited to the intended pressure range can be provided.

[0049] The refrigeration system may include an additional expansion device disposed in the return section and configured to reduce the refrigerant from the tertiary pressure range to the secondary pressure range. The pressure reduction may be achieved isenthalpic, thereby reducing both the pressure and temperature of the refrigerant in the return section. As the temperature is reduced, the refrigerant may transition from a gas and / or supercritical phase to a wet vapor phase.

[0050] A further expansion device can be arranged upstream of the secondary side of the heat exchanger and / or downstream of the first connection point. The secondary side can be thermally conductively connected to the primary side. The further expansion device can be configured to control the refrigerant flow to the return section. In particular, the further expansion device can be configured as a valve, the volume flow rate through the expansion device scaling with the opening of the expansion device. The opening of the expansion device can advantageously be controlled as a function of pressure and / or temperature. In particular, the expansion device can be used to control the refrigerant flow through the return section as a function of the temperature at the outlet of the second compressor or the hot gas temperature. The inlet temperature at the inlet of the second compressor can scale with the refrigerant flow through the return section. The refrigerant in the return section can have a lower temperature than the refrigerant between the compressors of the main circuit. The temperature at the inlet of the second compressor, and therefore indirectly also the temperature at the outlet of the second compressor, can be adjusted by the refrigerant flow through the return section.

[0051] The cooling system may comprise a further heat exchanger with a primary side arranged in the main circuit upstream of the expansion device and / or downstream of the cooling component, whereby the refrigerant can take up additional heat before the expansion device, but in particular also before the evaporator, thereby increasing the cooling capacity at the evaporator. On the primary side, the cooling can be performed isobarically, whereby the enthalpy can be reduced. On the secondary side, the heating can likewise be performed isobarically, whereby the enthalpy can be increased. The refrigerant can flow through the further heat exchanger in liquid phase.

[0052] By using post-injection and a heat exchanger, the coefficient of performance can be increased. Furthermore, the refrigerant can be further subcooled upstream of the expansion device by means of another heat exchanger. A higher specific evaporation capacity can thereby be achieved, which allows the refrigerant mass flow rate and thus the resulting compressor speed of the first compressor and / or the second compressor to be reduced. By additional injection via the return section, the evaporation capacity can be adapted and in particular increased.

[0053] The further heat exchanger may be arranged downstream of the primary side of the heat exchanger in the main circuit, and accordingly, the refrigerant in the main circuit may be cooled by the heat exchanger and the further heat exchanger.

[0054] The further heat exchanger may comprise a secondary side, which is arranged in the main circuit downstream of the evaporator and / or upstream of the first compressor. Furthermore, the further heat exchanger may be formed to absorb heat from the refrigerant by means of the primary side and to release the absorbed heat to the refrigerant by means of the secondary side in order to heat the refrigerant upstream of the first compressor. Accordingly, the further heat exchanger may realize a materially decoupled internal heat transfer between different sections of the main circuit. Heating of the refrigerant before the inlet of the first compressor may increase the temperature of the refrigerant, thereby overcoming in particular the wet vapor phase of the refrigerant, which is present in gas phase at the inlet of the first compressor. The refrigerant may already be at least partially present in gas phase downstream of the evaporator. However, at least a part of the refrigerant may still be present in liquid phase. For example, refrigerant droplets may float in the gas flow of the refrigerant. These refrigerant droplets may damage the compressor. Additional heating by another heat exchanger can reduce the volume of the refrigerant droplets or cause the droplets to at least partially evaporate in the refrigerant flow, thus advantageously protecting the first compressor from liquid hammer and / or reducing wear due to the reduced number and / or size of the refrigerant droplets.

[0055] Advantageously, the need for additional energy may be eliminated for heat transfer between the primary and secondary sides of the separate heat exchanger. This heat transfer may accordingly increase the efficiency and / or durability of the cooling system. The separate heat exchanger may cause pressure losses, which may be overcome or compensated for by the compressor.

[0056] The further heat exchanger can be a pipe-pipe heat exchanger, whereby advantageously the primary side is thermally but not materially connected to the secondary side. For example, the primary side can be connected to the secondary side via a thermally conductive material. In particular, a materially metallic connection can be realized in this case.

[0057] The cooling system may comprise a liquid separator configured to separate the refrigerant in a liquid state. Furthermore, the liquid separator may be arranged in the main circuit downstream of the evaporator and / or upstream of the first compressor. In the evaporator, the refrigerant may be present in a wet vapor phase, whereby heat is absorbed by the refrigerant isobarically and isothermally and an enthalpy gain is realized. This heat absorption may be utilized to cool laboratory equipment, in particular the rotor chamber of a centrifuge. At the outlet of the evaporator, the refrigerant may be present in a phase transition between the wet vapor phase and the liquid phase. In this case, a liquid collector may collect the still liquid part of the refrigerant in order to provide a pure gaseous refrigerant flow to the first compressor.

[0058] The liquid separator can be arranged upstream of the secondary side of the further heat exchanger. The secondary side of the further heat exchanger can thereby form a kind of refrigerant droplet filter that removes the refrigerant droplets passing through the liquid separator. With the liquid separator, the heating capacity of the further heat exchanger can be utilized to provide a pure gas phase of the refrigerant. In particular, the further heat exchanger can be formed such that its heating capacity is sufficient to remove the refrigerant droplets. However, the heating capacity can be smaller than the capacity that would allow the entire refrigerant flow to be transferred to the gas phase without the use of a liquid separator. Thus, the refrigerant can be provided to the first compressor in a gaseous state efficiently by the combination of the liquid separator and the further heat exchanger. Furthermore, the enthalpy can be increased isobarically through the secondary side of the further heat exchanger, which moves the refrigerant away from the phase transition between the wet vapor phase and the gas phase.

[0059] The cooling system may comprise a filter dryer which may be configured to remove moisture from the refrigerant. The moisture may advantageously be separated and / or filtered. The filter dryer may be located in the main circuit downstream of the refrigeration component and / or upstream of the expansion device. The filter dryer may advantageously be designed to bind moisture and / or acids present in the refrigerant. Advantageously, the filter dryer may filter dirt and / or other foreign matter present in the refrigerant. The advantage may be achieved that oxidation of the component oil may be inhibited, thereby protecting the compressor.

[0060] The filter-drier can be arranged in the main circuit between the primary side of the heat exchanger and the primary side of the other heat exchanger. Advantageously, the refrigerant can pass through the filter-drier in liquid phase. Filtering, especially before the expansion device, can avoid the formation of frozen water in the piping system, so that the flow of the refrigerant is not impeded. Furthermore, the first compressor can be protected from damage by ice particles.

[0061] The filter-drier can be arranged downstream or upstream of the first connection point, so that a partial flow of the refrigerant is fed to the return section before filtration.

[0062] The cooling system may comprise an intermediate pressure vessel, which may be configured to split the refrigerant into liquid and gas phases, and which may be located in the main circuit downstream of the cooling component and / or upstream of the expansion device. The intermediate pressure vessel may be a liquid separator, where a pressure in the secondary pressure range or an intermediate pressure prevails. The liquid separator separates the liquid and gas phases of the refrigerant at intermediate pressure. The liquid may be used as a vorlage for the expansion device, whereby the refrigerant flow flows in liquid phase from the liquid separator to the expansion device. The gas phase of the refrigerant may be fed to the second compressor via a return section. Advantageously, the second compressor may be configured to draw off the refrigerant in gas phase from the intermediate pressure vessel. This returned refrigerant gas may be mixed with the refrigerant gas from the first compressor. In one embodiment, the returned refrigerant gas may be mixed with the refrigerant of the main circuit in the primary pressure range. Whether the refrigerant is mixed in the secondary pressure range or in the primary pressure range may depend on the type of the first compressor.

[0063] The medium pressure vessel may be configured as a three-way collector and may include the following components: a vessel inlet configured to deliver refrigerant to the medium pressure vessel and disposed downstream of the cooling component; a first vessel outlet configured to deliver liquid refrigerant from the intermediate pressure vessel to the piping section 208 and / or located upstream of the expansion device; a second vessel outlet configured to couple the medium pressure vessel to the return section and to deliver gaseous refrigerant to the return section;

[0064] The vessel inlet can be located in the main circuit downstream of the heat exchanger and / or downstream of the filter-drier. Correspondingly, already filtered and / or cooled refrigerant can be provided to the medium pressure vessel.

[0065] The first connection point can be formed by a medium pressure vessel. The refrigerant in gas phase can be injected into the return section via the second vessel outlet. Due to phase separation, the refrigerant in gas phase can be introduced into the return section and the refrigerant in liquid phase can be fed to the expansion valve accordingly. The refrigerant in gas phase can have a higher enthalpy compared to the refrigerant in liquid phase. The first heat exchanger can provide additional heat input to the refrigerant in order to bring the refrigerant from the wet vapor to gaseous phase transition to a higher temperature and further into the gas phase. Thereby, in particular the liquid content of the refrigerant can be reduced before being injected into the main circuit upstream of the second compressor.

[0066] The intermediate pressure vessel may be configured to provide the refrigerant at the first vessel outlet, advantageously in a liquid phase, at least with a phase transition from the liquid phase to a wet vapor phase. The intermediate pressure vessel may provide for a reduction in enthalpy to such an extent that the refrigerant transitions from the wet vapor phase to the liquid phase. This reduction in enthalpy may be achieved isothermally.

[0067] The cooling system may include a high-pressure controller, which may be configured to reduce the pressure of the refrigerant, in particular to reduce the pressure from a tertiary pressure range to a secondary pressure range or to reduce the pressure within a tertiary pressure range. The temperature of the refrigerant may change, in particular when flowing through the high-pressure controller. The pressure control may be performed isenthalpic. In this case, the refrigerant may transition from a liquid phase to a wet vapor phase. Downstream of the high-pressure controller, the cooling system may have an enthalpy minimum, a pressure minimum, and / or a temperature minimum. Correspondingly, the heat absorption in the evaporator may be maximized.

[0068] The high-pressure control device can be arranged in the main circuit upstream of the intermediate pressure vessel and / or downstream of the cooling component, downstream of the first heat exchanger and / or downstream of the filter-drier. In particular, the high-pressure control device can be arranged at the vessel inlet of the intermediate pressure vessel in order to reduce the inlet pressure of the intermediate pressure vessel. Advantageously, the high-pressure control device is formed to bring about a phase transition of the refrigerant from a liquid or supercritical phase to a wet vapor phase. The pressure change can be realized isenthalpic.

[0069] The high-pressure controller can be controllable on the basis of pressure, in particular on the basis of the pressure of the refrigerant downstream of the cooling component. Alternatively, the pressure drop can also be controlled by the high-pressure controller on the basis of temperature, in particular on the temperature at the outlet of the first heat exchanger. Advantageously, the pressure at the outlet of the first heat exchanger can be used to control the high-pressure controller.

[0070] The high pressure controller may be controllable based on the pressure downstream of the first heat exchanger, based on the pressure upstream of the high pressure controller, and / or based on the pressure upstream of the filter dryer. Advantageously, the high pressure controller may be controlled based on the maximum pressure of the refrigerant.

[0071] The expansion device can be a superheat control device and can be configured to control the superheat of the refrigerant in the evaporator. This can achieve the advantage that the low pressure liquid separator can be omitted, i.e. the liquid separator in the primary pressure range can be omitted. Furthermore, the heating of the refrigerant upstream of the first compressor can be eliminated. Accordingly, by using the high pressure control device and the intermediate pressure vessel, the second heat exchanger can be omitted. Advantageously, the superheat control device can be configured to control the injection temperature in the evaporator to correspond to the saturation temperature.

[0072] The expansion device can be configured to control the pressure of the refrigerant, in particular to reduce the pressure of the refrigerant from a secondary pressure range to a primary pressure range or from a tertiary pressure range to a primary pressure range. By reducing the secondary pressure range to the primary pressure range by the high pressure control device, a pressure reduction from the tertiary pressure range to the secondary pressure range can be achieved upstream. This can be a single stage expansion, with two stage compression achieved by the first compressor and the second compressor.

[0073] The expansion device can be controlled based on the pressure, in particular based on the pressure of the refrigerant downstream of the evaporator and / or upstream of the first compressor. At the outlet of the evaporator, the cooling system can have a maximum enthalpy and the refrigerant can have a minimum pressure. The expansion device can be controlled accordingly depending on the pressure and / or temperature to be achieved at the outlet of the evaporator. Accordingly, the heat absorption in the evaporator can be increased. Advantageously, the inlet pressure and inlet temperature can be adjusted by the expansion device in such a way that the refrigerant can absorb as much heat as possible when flowing through the evaporator or achieve as large an enthalpy increase as possible, so that the cooling capacity of the evaporator is as large as possible. The evaporator can heat the refrigerant up to or beyond the phase transition from the wet vapor phase to the gas phase.

[0074] The expansion device may be controllable based on the pressure upstream of the further heat exchanger. For example, the pressure between the evaporator or expansion element and the first compressor can be sensed in order to control the opening of the expansion device. Thus, control of the expansion device can be realized independently of the heat input upstream of the first compressor, in particular independently of the heat input on the secondary side of the further heat exchanger.

[0075] The expansion devices may be controllable based on parameter values ​​of the intermediate pressure vessels to control the flow of refrigerant from piping section to piping section. The intermediate pressure vessels may be passive elements, and refrigerant flow through the respective vessel outlets may be controlled by a pressure differential downstream in the direction of the expansion device and / or another pressure differential in the return section.

[0076] The parameters may be the fill level, pressure, temperature and / or condensation state of the refrigerant in the intermediate pressure vessel. The fill level may correspond to the volume of refrigerant in liquid phase in the intermediate pressure vessel. Furthermore, the ratio of liquid and gas phases in the intermediate pressure vessel may be controlled by the outflow of refrigerant to the return section and downstream to the expansion device. Advantageously, the ratio of liquid and gas phases of refrigerant in the intermediate pressure vessel may be kept substantially constant.

[0077] The expansion device can be formed to detect the parameter values ​​of the medium pressure vessel. The expansion device can thus regulate the superheat of the refrigerant at the outlet of the evaporator. For example, the superheat can be in the range of 3 K to 10 K. The pressure and / or temperature can preferably be detected in the medium pressure vessel, in the medium pressure vessel or in the piping system in the immediate vicinity of the medium pressure vessel. A combination of pressure and temperature can indicate the proportion of gaseous refrigerant, preferably when only gaseous refrigerant is present. In this case, the pressure, in particular the pressure in the medium pressure vessel, can be controlled in order to obtain at least a portion of the refrigerant in liquid form in the medium pressure vessel. The pressure can be controlled, for example, by a valve connected downstream, in particular an expansion device. The liquid proportion of the refrigerant in the medium pressure vessel can be achieved by reducing the pressure (from the supercritical range). That is, if the refrigerant is in the supercritical state, the pressure can be reduced to transfer the refrigerant to a liquid state or to a wet vapor phase. If the pressure and temperature combination indicates only supercritical refrigerant in the vessel, the pressure can be reduced (opening the valve connected downstream, closing the valve connected upstream) in order to reach liquid or wet vapor in the vessel again, which is good for the capacity of the evaporator. If the state of the gas in the vessel is subcritical, the pressure increase can increase the amount of liquid in the vessel. By controlling accordingly, the cooling capacity of the evaporator can be increased. The control can be performed by combining the evaporator outlet temperature, the measured pressure and the saturation temperature derived therefrom with the pressure difference between the expansion device and the compressor inlet of the first compressor. In this case, the liquid separator between the evaporator and the compressor can be omitted.

[0078] The cooling system may comprise a second cooling component formed to cool the refrigerant and arranged downstream of the first compressor and / or upstream of the second compressor. The second cooling component may form an intercooler. Enthalpy may be removed from the refrigerant at constant pressure with the second cooling component. At the outlet of the first compressor, the cooling system may have a maximum enthalpy. The enthalpy may be reduced by the injection of cooled refrigerant from the intercooler and / or the return section. Advantageously, the enthalpy at the inlet of the second compressor may be a minimum in the gas phase. Accordingly, the enthalpy at the inlet of the first compressor may be higher than the enthalpy at the inlet of the second compressor. After compression by the second compressor, both the pressure and the temperature of the refrigerant may be higher than after compression by the first compressor. However, the enthalpy after the second compression may be lower than after the first compression.

[0079] The second cooling component may be configured to extract heat from the refrigerant and reject it to a central cooling system and / or to the surrounding atmosphere. Alternatively, a secondary cooling circuit may be used to reject the heat.

[0080] Compression of the second compressor may depend on the inlet temperature of the refrigerant at the inlet of the second compressor. Advantageously, cooling the refrigerant can reduce the optimum high pressure of the refrigerant or the high pressure generated by the second compressor. Cooling the refrigerant can prevent the critical operating temperature of the second compressor from being exceeded.

[0081] A second cooling component can be located upstream of the connection point, whereby the refrigerant can be first cooled by the second cooling component and then further cooled by mixing with the refrigerant flow from the return section, providing a two-stage temperature drop between the first and second compressors.

[0082] The second cooling component can be configured to cool the refrigerant when the refrigerant exceeds the ambient temperature to provide a refrigerant in gaseous form, in a secondary pressure range and at a reduced temperature at the outlet of the second cooling component. In particular, the temperature reduction by the second cooling component can be controlled such that the transition to the wet vapor phase is prevented. In particular, the control is also performed such that the combined cooling based on the second cooling component and the refrigerant supply via the return section achieves a temperature of the refrigerant at the inlet of the second compressor that is higher than the wet vapor phase transition.

[0083] The second cooling component can be configured to cool the refrigerant to a predetermined temperature, so that the refrigerant has a temperature below a limit temperature downstream of the second compressor. Here, taking into account the heating of the refrigerant by the second compressor, a limit value for the inlet temperature of the refrigerant in the second compressor can be defined, so that the second compression brings the refrigerant below its maximum temperature. The limit temperature can be determined such that the refrigerant has a subcritical temperature. The subcritical temperature can be adjusted at the inlet or outlet of the second compressor.

[0084] The second cooling component may include a ventilator configured to generate an air flow through the second cooling component to remove heat from the refrigerant, thereby dissipating the heat to the surrounding atmosphere.

[0085] The second vessel outlet can be connected to a second cooling component via a piping section, where the piping connection can include a branch to a second compressor, whereby the mixed refrigerant flows from the second cooling component and the intermediate pressure vessel to the second compressor, where a refrigerant flow from the return section can be added.

[0086] The first refrigerant flow can flow from the second cooling component to another connection point, and the second refrigerant flow can flow from the second vessel outlet to another connection point. Furthermore, the first refrigerant flow and the second refrigerant flow can be mixed at another connection point to form a combined refrigerant flow, and the mixed refrigerant flow can flow via the piping section to the second connection point and / or to the second compressor. This can realize a three-stage temperature regulation of the refrigerant between the first compressor and the second compressor. The first cooling can be achieved by the second cooling component, the second cooling can be achieved by the inflow of the refrigerant from the intermediate pressure vessel, and the third cooling can be achieved by the inflow of the refrigerant via the return section. This is a maximum configuration of internal cooling, and the cooling stages can be formed redundantly.

[0087] In particular, a valve for pressure regulation can be provided before and after the intermediate pressure vessel. Accordingly, a redundant pressure relief from the tertiary pressure range via the secondary pressure range to the primary pressure range can be realized by means of the valve and the intermediate pressure vessel. Overheat control can be realized both in the expansion device and in the high pressure control device. Here, a redundant high pressure control can be provided in order to prevent liquid hammer through the intermediate pressure vessel and the high pressure control device.

[0088] In the secondary pressure range, refrigerant may be allowed to enter the piping 204 from the return section through a second connection point. Refrigerant flow through the return section may be controlled by an intermediate pressure vessel or another expansion device.

[0089] The heat exchanger can be configured to provide a first specific enthalpy to the refrigerant at the second connection point and the second cooling component can be configured to provide a second specific enthalpy to the refrigerant at the second connection point, the first specific enthalpy being smaller than the second specific enthalpy, whereby it can be ensured that the refrigerant is further cooled and cannot be heated upstream of the second compressor by injection via the return section.

[0090] The refrigerant flow in the return section and the other refrigerant flow in the piping can be mixed to a combined refrigerant flow at a second connection point. The mixed refrigerant flow can be provided to a second compressor. At the second connection point, a temperature between the temperature of the refrigerant in the return section and the temperature of the refrigerant upstream of the second connection point in the main circuit can be adjusted by mixing the refrigerant flows according to the volume fractions of the refrigerant flows. Advantageously, at least two stages of temperature reduction can be achieved.

[0091] The second cooling component can be configured to cool the refrigerant based on the ambient temperature and / or based on the limit temperature of the evaporator. Advantageously, the ambient temperature is lower than the temperature of the refrigerant in the second cooling component in order to prevent heat absorption from the ambient air in the second cooling component. The higher the outlet temperature of the evaporator, the higher the ambient temperature at which the second cooling component can release heat to the ambient air. The cooling or enthalpy extraction by the second cooling component can be controlled in such a way that the formation of a liquid phase in the refrigerant flow to the second compressor is prevented.

[0092] In this case, the hot gas temperature, for example the temperature of the refrigerant downstream of the first compressor, can be scaled with the evaporation inlet temperature. The evaporator outlet temperature can correspond to the evaporator inlet temperature, since the enthalpy absorption in the evaporator can be carried out isothermally. At evaporation temperatures above -20°C, advantageously, another cooling component between the compressors can take heat from the refrigerant. In the range from -40°C to -20°C, the temperature at the outlet of the first compressor can correspond to the ambient temperature or be lower than the ambient temperature. For example, the temperature at the outlet of the first compressor can be less than 30°C. The hubvolumen of the first compressor and the pressure of the primary pressure range can be selected such that the temperature at the outlet of the first compressor is always higher than the ambient temperature. In this case, the maximum permissible ambient temperature can be defined as follows: for example, permissible operation of the cooling system at ambient temperatures up to 30°C, up to 35°C or up to 40°C can be defined.

[0093] The cooling system may include a circuit controller configured to control the flow of refrigerant, where, inter alia, heat absorption at the evaporator, heat release at the cooling components, and / or ambient temperature may alter the equilibrium state of the cooling system, such that the circuit controller can adjust the refrigerant flow accordingly to adjust optimal temperature and pressure values.

[0094] The circuit controller can be configured to control the opening of the expansion device depending on the pressure of the refrigerant, in particular the high pressure downstream of the cooling component and / or downstream of the second compressor. Depending on the opening of the expansion device, the decompression of the refrigerant downstream of the expansion device can be controlled. For this purpose, a pressure and / or temperature sensor can be provided at the outlet of the cooling component and / or a pressure and / or temperature sensor can be provided at the outlet of the second compressor.

[0095] The circuit controller can be formed to control the opening of the expansion device based on the pressure of the refrigerant downstream of the heat exchanger. For this purpose, a pressure and / or temperature sensor can be arranged at the outlet of the heat exchanger. Advantageously, the temperature can be detected upstream of the filter dryer. The controlled quantity can thus in this case be the pressure in the tertiary pressure range of the cooling system. The control path can include the piping system and components of the cooling system downstream of the first compressor and / or the second compressor, as well as upstream of the expansion device.

[0096] The expansion device can have a valve and can be configured such that the opening of the valve can be adapted stepwise or continuously from a fully closed state to a fully open state under a control of the circuit controller. By opening the expansion device, the volumetric flow rate of the refrigerant through the expansion device to the evaporator can be adjusted.

[0097] The circuit controller may be configured to control the opening of the expansion device based on the temperature of the refrigerant upstream of the first compressor and / or downstream of the evaporator, in particular the evaporator outlet temperature.

[0098] Depending on the opening of the expansion device, the decompression of the refrigerant downstream of the expansion device can be controlled, in particular the pressure drop, which can also lead to an isenthalpic temperature change.

[0099] The circuit controller can be configured to determine a predetermined temperature value and to control the opening of the expansion device if the predetermined temperature value is exceeded by a detected temperature, in particular the evaporator outlet temperature. The predetermined temperature value can be an empirical and / or calculated medium temperature.

[0100] The circuit controller can be formed to control the opening of the further expansion device depending on the temperature of the refrigerant downstream of the first compressor and / or downstream of the second compressor or the hot gas temperature, and depending on the opening of the further expansion device the decompression of the refrigerant downstream of the further expansion device can be controlled. In this case the compressor outlet temperature or the hot gas temperature can be defined as the controlled variable and the first compressor and / or the second compressor can be defined as the controlled path. In this case the pressure and / or the temperature of the refrigerant at the outlet of the second compressor can be detected. The refrigerant flow through the return section can thus be adapted in order to adjust the optimum hot gas temperature. The heat transfer of the heat exchanger from the main circuit to the return section can be controlled depending on the opening of the further expansion device. The further expansion device can advantageously adjust the pressure in the return device to a secondary pressure range. Depending on the opening of the further expansion device the predefined pressure value can be adjusted.

[0101] The circuit controller may be configured to control the opening of the high pressure controller in response to the pressure of the refrigerant downstream of the second compressor and / or upstream of the high pressure controller. Pressure sensors may be provided at the outlet of the heat exchanger, the outlet of the cooling component, and / or the outlet of the second compressor.

[0102] The circuit controller can be configured to control in response to pressure downstream of the heat exchanger and / or upstream of the filter dryer. The pressure sensed in the tertiary pressure range can be defined as the controlled quantity, and the section of the refrigeration system in the tertiary pressure range can be defined as the controlled path. For example, this could be the refrigerant path from the outlet of the second compressor to the inlet of the high pressure control device, or to the intermediate pressure vessel, or to the expansion device.

[0103] The cooling system may have a compressor drive configured to drive the first compressor and / or the second compressor. Thereby, the advantage of being able to drive and control both the first and the second compressor via a common drive may be achieved. In this case, each of the compressors may be driven separately, i.e. supplied with different drive forces. The first compressor and the second compressor may be arranged in a common housing. Furthermore, the compressor drive may be a motor, which may be configured to drive the first compressor and to drive the second compressor.

[0104] The compressor drive can be configured to control the respective compressor speed of the first compressor and / or the second compressor as a function of the pressure of the refrigerant downstream of the expansion device, in particular the evaporation pressure, and / or the temperature of the refrigerant, in particular the evaporation temperature, and the compression capacity of the first compressor and / or the second compressor can be controlled as a function of the compressor speed. This can provide the advantage that a predefined evaporation temperature, i.e. the temperature during isothermal enthalpy absorption in the evaporator, can be adjusted via the compressor speed. In this case, the evaporation pressure or the evaporation temperature can be defined as the controlled variable, and the compressor power or the speed can be defined as the control path.

[0105] The first compressor, the second compressor and / or the compressor drive may each have a drive and may be configured to adapt the speed of the respective drive in a stepwise or continuous manner within a predefined range from a minimum speed to a maximum speed under the control of the circuit controller, thereby realizing a particularly efficient control of the compressor.

[0106] The circuit controller can be configured to control the compressor speed based on a predetermined evaporating temperature. For example, the compressor speed of the first compressor and / or the second compressor can be increased to decrease the evaporating temperature. The compressor speed of the first compressor and / or the second compressor can be decreased to increase the evaporating temperature. The circuit controller can be configured to increase and / or decrease the compressor speed.

[0107] The cooling component may include a ventilator configured to direct an airflow through the cooling component for cooling, whereby the cooling component may be thermally coupled to the surrounding atmosphere.

[0108] The cooling component may include a refrigerant-brine heat exchanger configured to transfer heat from the refrigerant to the brine (Sole).

[0109] The circuit controller can be configured to control the fan speed of the ventilator as a function of the temperature of the coolant downstream of the cooling component, in particular the cooling component outlet temperature, and the cooling capacity of the cooling component can be controlled as a function of the fan speed. The airflow to the cooling component can be scaled by the fan speed. Advantageously, the cooling capacity of the cooling component can also be scaled, at least in part, by the fan speed.

[0110] The ventilator can be configured such that the ventilator speed is adapted by the circuit controller in a stepwise or continuous manner within a predetermined range from a minimum speed to a maximum speed under control.

[0111] The circuit controller can be configured to control the ventilator in multiple stages depending on the thermal load, where in a first control stage the ventilator rotation speed is zero, in a second control stage the ventilator rotates at a first rotation speed greater than zero, and / or in a third control stage the ventilator rotates at a second rotation speed, the second rotation speed being greater than the first rotation speed.

[0112] The circuit controller can be configured to control the pressure in a tertiary pressure range such that the cooling capacity is maximized. In particular, it can be adjusted to an optimum high pressure. The optimum high pressure can depend on the ambient temperature and, accordingly, on the cooling capacity of the cooling component. The optimum high pressure can vary depending on whether subcritical or supercritical operation is involved. For example, the optimum high pressure can be about 100 bar for a supercritical cycle and about 50-60 bar for a subcritical cycle.

[0113] The circuit controller can be configured to control the superheat of the evaporator by the expansion device so that the superheat is minimized, in particular at least 3 K at the compressor inlet of the first compressor. This can achieve the advantage that the first compressor can be protected from liquid hammer by the refrigerant in the liquid phase. In the evaporator, the process can be carried out substantially isothermally and isobarically up to the structural end of the evaporator tubes of the evaporator. The superheat of the refrigerant can be realized at the structural end of the evaporator. By minimizing the superheat at the outlet of the evaporator, the cooling capacity can be maximized and the temperature at the inlet of the evaporator is advantageously equal to the saturation temperature.

[0114] The circuit controller may be configured to control the compressor outlet temperature of each of the first compressor and / or the second compressor by means of a separate expansion device to maintain the compressor outlet temperature below a predetermined limit temperature.

[0115] To lower the compressor outlet temperature, cooled refrigerant from the return section can be injected at the second connection point.

[0116] The circuit controller can be formed to control the first compressor speed of the first compressor and the second compressor speed of the second compressor in a stepless manner, respectively. Furthermore, the circuit controller can be formed to control the first compressor speed and the second compressor speed, respectively, independently of one another. Thereby, an optimal compression of the refrigerant can be achieved by the respective compressors, in particular an optimal high pressure can be adjusted. Vibrations can be reduced by the independent stepless control of the compressors. Advantageously, if the cooling system is used in a centrifuge, the transmission of vibrations to the sample can be reduced, which can increase the centrifugation quality. Furthermore, the user's perception can be improved by reducing the noise emission or vibrations of the centrifuge. The speed controller allows a soft start to be realized, i.e. the first compressor and / or the second compressor can be driven for a predefined time, for example between 60 and 120 seconds after the start-up process with reduced acceleration. Thus, improved centrifugation quality, improved centrifugation and improved user perception can be achieved. Advantageously, the first and second compressors can be formed by two compression chambers in a compressor module. The first and / or second compressors can each have a predefined starting speed, whereby the compressors only start above a predefined frequency and / or voltage threshold, i.e. the compressors start at a low threshold speed or excitation speed.

[0117] The circuit controller can be configured to accelerate the first compressor and / or the second compressor to a respective predefined target speed with a respective predefined acceleration value during the start-up phase. In particular, the acceleration is 8 revolutions / s 2 or less. In this case, the predetermined target speed may constitute a limit value for distinguishing between reduced and increased acceleration. By reducing the acceleration, a reduction in vibrations in the laboratory equipment can be advantageously achieved. In another advantageous embodiment, the circuit controller is adapted to operate at a reduced acceleration, in particular 8 revolutions / s 2After the first acceleration phase with the following acceleration, in the second acceleration phase, the first compressor and / or the second compressor are operated at 8 revolutions / s 2 The advantage can thereby be achieved that the oil flow, in particular the compressor oil flow, can also be accelerated.

[0118] In an embodiment of the invention, it is also possible to provide that the cooling system is designed to operate the first compressor and / or the second compressor at a first rotational speed and at a second rotational speed greater than the first rotational speed, the cooling system being further designed to assume rotational speeds between the first and second rotational speeds (i.e. only for a moment during speed changes). In other words, operational vibrations can be avoided, which in turn can avoid resonant excitations, especially at such speeds.

[0119] The circuit controller can be designed to control the ventilator speed depending on the acceleration rate of the first compressor and / or the acceleration rate of the second compressor, in particular to control it steplessly. The ventilator speed can be controlled depending on the compressor acceleration rate, so that the ventilator speed can increase with increasing speed of the first compressor and / or the second compressor. The thermal load of the cooling component can be directly proportional to the compressor speed of the first compressor and / or the second compressor.

[0120] The control characteristic curve of the ventilator can precede the control characteristic curve of the first compressor and / or the second compressor. The ventilator can be started with a gently rising characteristic curve. The first compressor and / or the second compressor can also be started with a similarly gently rising characteristic curve. The characteristic curve of the ventilator can precede the characteristic curve of the compressor in order to generate a power reserve, i.e. the ventilator can be accelerated first before the compressor is accelerated, and the compressor can follow. Thereby, the advantage that the load-adaptive control of the ventilator reduces the primary energy consumption can be achieved. Furthermore, the noise emission of the cooling system or of the laboratory equipment can also be reduced.

[0121] The circuit controller can be configured to control the fan speed of the ventilator as a function of the ambient temperature, in particular proportional to the ambient temperature, which can be detected at the air outlet of the laboratory equipment, in particular the cooling component. If the ambient temperature decreases, for example below 22° C., the ventilator of the cooling component can rotate at a reduced fan speed. If the ambient temperature increases, for example above 24° C., the fan speed can be increased compared to operation at a normal temperature, for example 23° C. A temperature window can be defined around the ideal ambient temperature. For a given ambient temperature, for example 23° C., the temperature window can be, for example, 2 K, i.e. 1 K above and 1 K below. The ventilator can rotate at an advantageous optimum speed within the temperature window. Depending on the fluctuations in the ambient temperature, the circuit controller can control this optimum speed steplessly up or down. The performance of the cooling component can thus be increased in order to take high ambient temperatures into account. High ambient temperatures can reduce the temperature difference between the cooling medium, for example the ambient air flow, and the refrigerant, which can then lead to reduced performance. This loss of performance can be compensated for by increasing the ventilator speed.

[0122] The circuit controller can be configured to control the expansion device depending on the outlet temperature of the cooling component and / or the ambient temperature in order to adjust the pressure to a tertiary pressure range, in particular the optimum high pressure. The ambient temperature adapted high pressure control allows for a machine specific increase in cooling capacity, in particular for centrifuge specific, special ambient and even operating conditions.

[0123] The expansion device may include a thermostatic valve or an electronic expansion valve. The electronic expansion valve may be controlled by a circuit controller. The thermostatic valve may be independently operated depending on a temperature value.

[0124] The circuit controller can be configured to detect changes in ambient temperature and control the expansion device, compressor speed, and / or ventilator speed based on the changes in ambient temperature. By controlling the ventilator and linking it to the compressor, changes in ambient temperature can be accommodated. An increase in ambient temperature, and therefore an increase in optimal high pressure, can be accommodated by closing the expansion device, increasing the compressor speed, or reducing the ventilator speed. These measures can increase the high pressure, or pressure at the outlet of the second compressor, and therefore achieve optimal performance.

[0125] According to a second aspect, the invention relates to a laboratory instrument comprising a cooling system. For example, the cooling system can be designed as described above. In particular, the laboratory instrument can be a centrifuge, an incubator and / or a biological safety cabinet. Advantageously, the cooling system can cool parts of the laboratory instrument, such as a cooling chamber, a sample chamber and / or a centrifuge rotor. In this case, temperature regulation can also be realized, whereby the parts can be controlled at a predetermined temperature.

[0126] The laboratory equipment may furthermore be mixing tanks, stirring vessels, reactors and / or general temperature-controlled laboratory equipment, e.g. refrigerators or freezers, especially for biological or chemical samples. For this purpose, a cooling system can be integrated into the respective laboratory equipment or connected to a cooling system via a piping system for heat exchange.

[0127] The laboratory equipment may be a benchtop or floor-standing equipment. Advantageously, the cooling system may be integrated into the housing of the laboratory equipment. In particular, the cooling system may be configured to provide cooling capacity independent of an external cooling circuit in the laboratory equipment.

[0128] The laboratory equipment may comprise a rotor tank in which an evaporator is arranged. The evaporator may be thermally coupled to the rotor tank in order to remove heat from the rotor tank. In this way, cooling of the rotor tank, and in particular of the biological sample arranged in the rotor tank, may be achieved.

[0129] The evaporator may comprise an evaporator winding arranged outside the rotor tank, the evaporator winding being formed by a surrounding wiring. The evaporator winding may extend in a spiral shape around the rotor tank. In particular, the abutment surface of the evaporator winding on the rotor tank may be maximized to achieve a thermal coupling between the evaporator winding and the rotor tank.

[0130] The evaporator winding may have a shape, in particular a D-shape, that is flattened on at least one side to form a flat surface that abuts against the outer surface of the rotor tank to form a surface contact, thereby advantageously increasing the heat flow from the rotor tank to the evaporator winding.

[0131] The evaporator winding can have an outer tube diameter ranging from 5 mm to 20 mm, in particular 10 mm or 16 mm. Furthermore, the evaporator winding can have a wall thickness of 0.5 mm to 5 mm, in particular 1 mm. By reducing the outer tube diameter, the surface contact of the evaporator winding with the rotor tank can be advantageously increased. If a smaller outer tube diameter is used, the number of turns of the evaporator winding on the outer surface of the rotor tank can be increased. Thereby, a larger rotor tank area can be covered by the evaporator winding while the rotor tank area remains the same. The spacing between the turns of the evaporator winding can be reduced. Thereby, advantageously, a smaller temperature difference between the sample in the rotor tank and the evaporation temperature can be obtained. The possibility of using smaller outer tube diameters, in particular 10 mm or 12 mm tubes instead of 16 mm tubes, can be associated with the use of CO2 as the refrigerant. As the tube cross-sectional area decreases, the pressure drop in the evaporator can be increased. Advantageously, the heat transfer area can be maximized and the pressure drop can be minimized.

[0132] The increase in the contact area between the evaporator winding and the rotor tank can result in a change in the temperature difference between the tube inner surface and the tank inner surface. The temperature of the tank inner surface can approach the evaporation temperature due to the area expansion. Thereby, a lower control temperature, especially a lower tank temperature, and therefore better sample cooling can be achieved. Furthermore, the reduction in the tube diameter can realize cost benefits.

[0133] The rotor tank may have a side jacket surface, a bottom jacket surface and a bottom surface, the side jacket surface being formed cylindrically and the bottom jacket surface having a curved contour and being formed to connect the side jacket surface with the bottom surface. Advantageously, the wiring of the evaporator winding is pressed into a D-shape on the side jacket surface.

[0134] The evaporator windings can be disposed on the side jacket surface, the bottom jacket surface, and / or the bottom jacket surface, which advantageously increases the contact area between the evaporator windings and the rotor tank to maximize heat transfer from the rotor tank to the evaporator.

[0135] The evaporator winding can form a surface contact with the lateral jacket surface. The surface contact can be a continuous surface, and the respective contact surfaces of the individual turns of the evaporator winding are arranged next to each other such that the turns abut each other in a form-fitting manner and no empty space is formed. The empty space can have a substantially triangular shape. The surface area of ​​the empty space can scale with the outer tube diameter of the evaporator winding and can accordingly be smaller in proportion to the reduction in the outer tube diameter.

[0136] The laboratory equipment may include a user interface, which is configured to transmit a target temperature and / or a rotor speed of a rotor disposed in a rotor tank to the circuit controller based on a user input. In this case, the target temperature may be a setpoint of a control temperature, in particular a tank temperature. The control temperature may be selected according to the design of the laboratory equipment.

[0137] Based on the rotor speed, the rotor speed change, the target temperature, and the difference between the current control temperature and the target temperature and / or the ambient temperature, the circuit controller can control the compressor speed of each of the first compressor and / or the second compressor, the ventilator speed of the ventilator in the refrigeration component, and / or the opening of the expansion device.

[0138] The circuit controller may be configured to compare the target temperature input with the detected temperature of the rotor tank and determine a temperature difference. The circuit controller may further be configured to adapt the compressor speed, regulate the ventilator, adapt the ventilator speed, and / or adapt the expansion device opening if the temperature difference exceeds a difference threshold. The difference threshold may be in the range of 1 K to 10 K, in particular the difference threshold is 5 K. In particular the compressor speed, the ventilator speed, and / or the expansion device opening may be reduced or increased by 20%, respectively. The percentage change may be with respect to the respective maximum values, i.e. compressor final speed, ventilator final speed, and maximum opening angle.

[0139] The circuit controller can furthermore be configured to detect whether a control triggered by a setpoint temperature input of the expansion device, in particular a corresponding opening, reduces or eliminates superheating in front of the first compressor, and the control can be prevented on the basis of the setpoint temperature input. Correspondingly, the circuit controller can be configured to detect superheating and to discontinue the control if the superheating is less than 1 K. Alternatively, the circuit controller can be configured to control the expansion device or the corresponding valve such that the corresponding valve is completely closed. An optimal high pressure can thereby be advantageously adjusted.

[0140] In particular, the circuit controller can be configured to perform expansion device opening changes with a time delay, advantageously a 30 second offset, to change the compressor speed.

[0141] The circuit controller can furthermore be configured to detect a temperature difference between the cooling component outlet temperature at the cooling component outlet and the ambient temperature and to prevent the adaptation of the ventilator speed based on the changed setpoint temperature input if the temperature difference reaches +3 K. Advantageously, the circuit controller is configured to execute a change in the ventilator speed from a temperature difference of +5 K. If an improvement to the temperature difference range of <5 K is not achieved by changing the ventilator speed by 20%, a new adaptation of the ventilator speed can be executed. Only then is the change made in the next control step. In this case, the circuit controller can be configured to execute an adaptation of the compressor speed as a first control step, an adaptation of the ventilator speed as a second control step and an adaptation of the expansion device opening as a third control step. In this case, the circuit controller can be configured to execute the control steps in the order of the first control step, the second control step and the third control step.

[0142] If the deviation of the control temperature is >3 K, then the circuit controller can execute, along with the control cycle with each 20% step, another control cycle with each 10% step. The 10% steps can also be for the respective maximum values, i.e. compressor final speed, ventilator final speed and maximum opening angle. This can achieve the advantage that the control temperature can be brought closer to the target temperature in stages. The last control cycle can be executed with a control step in the range of 1% to 5%, in particular 2%.

[0143] Various advantages can be achieved by the above-described embodiments.

[0144] For example, the range of application of the corresponding system (and centrifuges with such a system) can be extended. Such an extension can be the result of a special two-stage design in combination with R744 (i.e. CO2). For example, it may be possible to extend the range of application to ambient temperatures up to 40°C. For example, a single-stage fully sealed installation can be combined with R744 and achieve a maximum operating pressure of 75 bar with a vapor pressure in the range of 10 bar to 30 bar, which corresponds to approximately 35°C.

[0145] The upper limit of use for a hermetic, single-stage compressor is the supercritical range. That is, in general, a single-stage compressor can only be used in the subcritical range in the long term due to the limited pressure difference. An embodiment of the present technology overcomes this by using the refrigerant CO2 in combination with two compressors connected in series, which is not limited to the subcritical range and allows the system to operate in the supercritical range as well. In particular, with a single compressor, the achievable pressure difference from the lower stage to the upper stage may be too small for vapor pressures in the range of 10 bar to 30 bar. The high pressure may depend on the ambient temperature. Advantageously, by using at least two compressors, a low low pressure can be achieved even at high ambient temperatures, especially ambient temperatures above 30°C.

[0146] The use of two compressors connected in series can be advantageous compared to the use of a single compressor, especially when using CO2 as the refrigerant, given the following:

[0147] For compressors, the following technical parameters are of particular importance: The geometric volume flow rate, which is determined by the product of the area of ​​the compression cylinder, the height of the compression cylinder, and the number of revolutions per second of the compressor drive; Actual volume flow rate; · Volumetric efficiency, which may depend on pressure ratio (inlet pressure vs. outlet pressure), hazardous space and / or leakage.

[0148] Volumetric efficiency can also be determined by a quality class related to the volumetric flow rate. The quality class related to the volumetric flow rate represents the re-expansion into the hazardous or dead space (e.g. the distance between the piston and the cylinder cover) based on the design. The actual volumetric flow rate is reduced by the re-expansion into the hazardous space. The higher the pressure, the more refrigerant with higher enthalpy expands back into the hazardous or dead space (at the beginning of the downward movement of the piston and the start of the suction cycle). This refrigerant expands as the piston moves downward. The refrigerant sucked in from the low pressure side mixes with the re-expanded refrigerant. Thus, the enthalpy increases at the beginning of compression and the compressor outlet temperature rises. The latter is manifested by a translation of the compression line towards higher enthalpy in the log(p)-h diagram.

[0149] Additionally, the volumetric efficiency can also be determined by the wall quality rating, which describes the extent to which the gas entering from the low pressure side is heated before compression due to secondary effects such as heating at the cylinder walls, steam friction, etc. This warming is preferably kept low, as it reduces the density and therefore the actual volumetric flow rate.

[0150] In addition to this, the volumetric efficiency can be determined together with the leakage loss (Laessigkeitsgrad). The leakage loss (Laessigkeitsverluste) increases with increasing compression end pressure and decreases with increasing compressor speed, since less time is available for steam exchange.

[0151] The quality ratings related to volumetric flow rate and wall quality ratings are negatively correlated with the pressure ratio, while the permeability is correlated with the compression end pressure.

[0152] The increasing pressure ratio with single stage compression reduces the volumetric efficiency to the point where the compression temperature increases very rapidly and the enthalpy increase during polytropic compression far exceeds that of isentropic compression. Compression then takes place under a much increased entropy, which manifests irreversible losses during compression. This reduces the cooling capacity and increases wear. The use of two compressors in series can achieve the following advantages compared to a single compressor: With two compressor stages, the pressure ratio decreases as a function of losses, and cooling can be provided in the intermediate pressure stage, which improves the volumetric efficiency and reduces losses during compression.

[0153] The increase in entropy during compression can also be expressed by the polytropic ratio = dh / dy. Depending on the specific flow behavior, the polytropic ratio can be defined as:

number

[0154] Furthermore, a division into two compressors is also advantageous, since the suction conditions at low and medium pressure can be different. The volume at the compressor outlet is very large, i.e. a large hub volume is required here. Due to the small pressure difference, the driving force can be smaller than would be the case with single-stage compression. The same idea applies to the second stage, only now the volume is smaller and the driving force is greater.

[0155] Furthermore, the embodiment of the present technology allows the optimum cooling capacity to be achieved by adjusting the optimum high pressure. The optimum high pressure in the cooling circuit (high pressure value for the optimum cooling capacity), which depends crucially on the ambient temperature (or the temperature at the outlet of the gas cooler), can only be achieved by two-stage compression at a relatively high ambient temperature. Depending on the given low pressure and the resulting pressure ratio for the optimum high pressure, a single-stage compressor may never economically and efficiently achieve the optimum high pressure, or only temporarily. This means that a two-stage cooling circuit is advantageous to achieve the maximum cooling capacity with the centrifuge and its operating conditions (partially up to 40°C). The maximum stroke between low pressure and high pressure of current single-stage compressors is usually 40-60 bar in a fully hermetic configuration (supercritical range is only temporarily used), and the use of a fully hermetic compressor is advantageous, since in a semi-hermetic compressor, the inner space in which the centrifuge mainly operates may be critical (harmful physiological effects of CO2 on the human body).

[0156] As already explained, the embodiments of the present technology are particularly directed to the cooling system being used in a centrifuge. Such use may also be advantageous in terms of heat load. A centrifuge differs from other applications in terms of heat load, and therefore benefits from two-stage compression. Whereas the heat load in a centrifuge is dynamic (different from other applications of compression pressure relief cooling circuits), a refrigerator or freezer application can be considered to be rather static. In a refrigerator or freezer, the operator can leave the door open to the maximum extent and close the refrigerator with a delay. The evaporating temperature is always in a relatively narrow range. Leaving the door open can cause short-term variations in the required cooling capacity. In contrast, in a centrifuge, the heat load can vary over time due to the different rotors used (types, speeds, target temperature adjustments by the operator, imbalances, loads). Therefore, the use of variable post-injection to control the hot gas temperature at the compressor outlet is advantageously necessary to take into account the variable loads in the evaporator.

[0157] In the embodiments of the above technique, a soft start or separate start can be provided. In the embodiments where the system is part of a centrifuge, this can improve the quality of the centrifugation. In other words, the R744 compressor offers advantages in terms of start behavior. By controlling the two compressors independently of each other in a stepless manner, vibrations that may affect the sample and centrifuge chambers or the user's perception can be reduced. A soft start, i.e. running the two-stage compressor with a small acceleration for 60-120 seconds after the start process, has a positive effect on the centrifugation quality, the centrifuge, and the user's perception (especially if the compressor has two compression chambers). In general, the compressor may have a set start speed that first starts the compressor if a certain frequency or voltage threshold is exceeded. That is, the compressor starts softly (low threshold or excitation speed) and then starts running at a low speed. The speed acceleration should ideally be small (for example less than 8 revolutions / s per 10 seconds, i.e. an acceleration of 8 revolutions / s per second is the threshold acceleration rate for distinguishing between soft and fast acceleration of the compressor). A smaller acceleration rate will cause the device to vibrate less.

[0158] Furthermore, embodiments of this technology allow for increased operator comfort through infinitely variable fan control based on the compressor acceleration rate. Depending on the compressor acceleration rate, the fan speed can be controlled (higher compressor speeds result in higher gas cooler or condenser loads). This means that the fan can be configured as an infinitely variable controllable fan. The fan can be started with the gently rising characteristic curve described above (like the compressor characteristic curve). The fan characteristic curve can precede the compressor characteristic curve to obtain power reserves (i.e. the fan is accelerated first before the compressor is accelerated, and then the compressor follows). The advantage of this type of control is the use of a fan adapted to the load, resulting in less primary energy usage. This control can further achieve the advantage of reducing the upward swings of the high pressure to intermediate pressure ratio. By reducing the fan power, the noise emissions of the fan can be advantageously reduced.

[0159] The described embodiment of the technology also allows the cooling circuit operating conditions to be adjusted as a function of the ambient temperature (depending on the variable thermal load of the rotor and the installation conditions). In other words, in an R744 circuit, the fan speed can be related to the ambient temperature (around the device) measured at the outlet of the gas cooler. The cooling device may in particular include a fan, and the fan speed should be understood to indicate the speed of this fan. If the ambient temperature is low (e.g. below 22°C), the fan of the gas cooler may rotate relatively slowly. If the ambient temperature is high (e.g. above 24°C), the fan may rotate faster than at 23°C. That is to say, the window around the ideal ambient temperature of 23°C may be, for example, 2 Kelvin, one Kelvin above and one Kelvin below, within which the fan rotates at the ideal speed. Depending on the variation of the ambient temperature, deviations from this speed can be made stepwise upwards or downwards. In this way, the power of the gas cooler is increased stepwise to take into account the increase in the ambient temperature. The increase in the ambient temperature reduces the temperature difference between the cooling medium and the refrigerant, thereby reducing the power. This can compensate for the increased fan speed at 23°C deviation.

[0160] Furthermore, by means of an electronic or thermostatic expansion valve in the return section, the optimum high pressure for the cooling capacity at the evaporator can be adjusted depending on the ambient temperature (around the device). This allows for a load-specific and therefore centrifuge-specific performance increase for special ambient and application conditions, i.e. the ambient temperature of the centrifuge also depends on the waste heat (rotor-specific) and on the installation location. Thus, by controlling the fan and linking several compressors or a single compressor, it is possible to react to any changes in the ambient temperature. An increase in the ambient temperature (and therefore an increase in the optimum high pressure) can be countered by closing the valve, increasing the compressor speed or decreasing the fan speed. With these measures, a high pressure and therefore an optimum performance can be achieved.

[0161] In an embodiment of the present technology, the system can be operated with a control system adapted to a two-stage CO2 cooling system. In this case, it should be understood that a two-stage CO2 cooling system refers to a cooling system in which CO2 is used as a refrigerant and two compressors are arranged in series. In particular, the control system can be used in a centrifuge with a corresponding cooling system. This allows a relatively accurate temperature control to be achieved.

[0162] For example, when the rotation speed or the target temperature is changed by the operator on the operation panel during operation, the current tank temperature deviation, the ambient temperature, and the degree of the rotation speed change are -speed of one / several compressors, - the speed of the fan or gas cooler, or - Valve openings involved in recirculation has an impact on.

[0163] In particular, such a system can be operated with the following control scheme: If the new target temperature is >5 Kelvin above or below the currently measured temperature (in this order): The compressor speed is reduced or increased by a certain value (e.g. 20% of the final speed), - The fan speed is reduced or increased by a certain value (e.g., 20% of the final speed), The valve opening is increased or decreased by a certain value (e.g. 20% of the maximum opening angle).

[0164] An increase in temperature (i.e. an increase in the target temperature) can open the valve, and a decrease in temperature (i.e. a decrease in the target temperature) can close the valve. Opening the valve can reduce superheat. Correspondingly, the mass flow rate and therefore the cooling capacity can be increased.

[0165] If the valve opening results in the loss of superheat before the first compression stage, then no valve control process is performed. The valve opening change can be performed with an offset of, for example, 30 seconds, to change the compressor speed.

[0166] If the gas cooler outlet temperature is +3 Kelvin from the ambient temperature, no speed change is made. A change in the fan speed is only made if the deviation in the gas cooler outlet temperature is 5 Kelvin. If a change of 20% does not improve the deviation range to <5, a new change in the fan speed is made. Only then is a change to the next change step made.

[0167] If the control temperature deviation is > 3 Kelvin (after the upper control cycle has finished), the steam process is repeated and adapted by 10% (maximum opening or speed of the part).

[0168] In this way, the target temperature can be approached step by step. The final iteration loop can be lowered to around 5%. If appropriately fast controllers and components are used, this threshold can possibly be set to 2%. In this regard, a balance can be made between switching frequency and control quality, since frequent switching can wear out components.

[0169] Overall, it can also be seen that the two-stage compression according to the invention may potentially result in a relatively high hot gas final temperature or a high temperature at the outlet of the second compression stage, and therefore in an embodiment of the invention means are provided to reduce this temperature, for example a return section or a second cooling component.

[0170] Below, system embodiments are presented. These embodiments are abbreviated by the letter "S" followed by a number. Hereinafter, these embodiments are meant whenever reference is made to "system embodiments."

[0171] S1. A cooling system (10), comprising: Evaporator (11), A first compressor (12), A second compressor (14), Cooling components (16), An expansion device (18), and a piping system (20', 21') connecting the evaporator (11), the first compressor (12), the second compressor (14), the cooling component (14) and the expansion device (18) to each other; The cooling system (10) contains a refrigerant, the refrigerant being carbon dioxide; A refrigeration system comprising a first compressor (12) and a second compressor (14) disposed in series with one another.

[0172] S2. A cooling system (10) according to any of the above embodiments, wherein the cooling component (16) comprises a gas cooler and / or a condenser.

[0173] S3. A refrigeration system (10) according to one of the above embodiments, wherein the refrigeration system is configured to perform a supercritical vapor compression cycle.

[0174] S4. A cooling system (10) according to one of the above embodiments, wherein the cooling system is configured to perform a subcritical vapor compression cycle.

[0175] S5. A cooling system according to one of the above embodiments, wherein the cooling system has a cooling capacity of 10W to 100kW, in particular 500W to 10kW.

[0176] S6. A cooling system (10) according to one of the above embodiments, wherein the cooling system has a main circuit, the main circuit comprising: the compressor includes an evaporator (11), a first compressor (12), a second compressor (14), a refrigeration component (16), an expansion device (18), and at least a portion of a piping system (20', 21'); A cooling system in which the refrigerant is present in the main circuit.

[0177] S7. A cooling system (10) according to one of the above embodiments, wherein the cooling component (16) is disposed downstream of the second compressor (14) and upstream of the expansion device (18).

[0178] S8. A cooling system (10) according to one of the above embodiments, wherein the cooling component (16) is configured to cool a refrigerant downstream of the second compressor (14).

[0179] S9. A cooling system (10) according to one of the above embodiments, comprising: 1. A refrigeration system in which, if refrigerant leaves a first compressor at an outlet temperature, the refrigerant is delivered to a second compressor at an inlet temperature that is lower than the outlet temperature.

[0180] S10. A cooling system (10) according to any of the above embodiments, wherein the inlet and outlet temperatures differ by a temperature difference of more than 1 K, in particular more than 2 K, more particularly more than 3 K.

[0181] S11. In the cooling system (10) according to the above embodiment, the first compressor (12) and / or the second compressor are compressors of the following types: -Scroll compressors, -Reciprocating compressors, -Screw compressors, -Rotary piston compressor The cooling system is formed as one of the

[0182] S12. A cooling system (10) according to one of the above embodiments having the features of embodiment S6, wherein the cooling system (10) has a return section (40) fluidly connected to the main circuit at a first connection point (42) and a second connection point (44), the second connection point (44) being located in the main circuit downstream of the first compressor (12) and upstream of the second compressor (14).

[0183] S13. A cooling system (10) according to one of the above embodiments having the features of embodiments S9 and S12, wherein the cooling system (10) is configured such that at the second connection point (44) the refrigerant in the return section (40) has a lower specific enthalpy than the refrigerant immediately upstream of the second connection point (44) in the main circuit.

[0184] S14. A cooling system (10) according to one of the above embodiments having the features of embodiment S12, comprising a heat exchanger (48), the heat exchanger (48) comprising a primary side arranged downstream of the cooling component (16) in the main circuit, the heat exchanger (48) being configured to cool a refrigerant in the main circuit.

[0185] S15. A cooling system (10) according to one of the above embodiments having the features of embodiment S14, wherein the heat exchanger (48) is configured to bring the refrigerant to a predetermined temperature at the first connection point (42) and / or the piping section (208) that is less than the outlet temperature of the cooling component (16).

[0186] S16. A cooling system (10) according to one of the above embodiments having the features of embodiment S15, wherein the heat exchanger (48) is arranged upstream of the expansion device (18) in the main circuit.

[0187] S17. A cooling system (10) according to one of the above embodiments having the features of embodiment S15, wherein the heat exchanger (48) has a secondary side arranged in the return section (40), and the heat exchanger (48) is configured to absorb heat from the refrigerant by the primary side and to release the absorbed heat to the refrigerant by the secondary side in order to heat the refrigerant in the return section (40).

[0188] S18. A cooling system (10) according to one of the above embodiments having the features of embodiments S12 and S17, wherein the secondary side is arranged upstream of the second connection point (44) in the return section (40).

[0189] S19. A cooling system (10) according to one of the above embodiments, wherein the first compressor (12) is configured to compress a refrigerant from a first pressure range to a second pressure range, the second pressure range having a higher pressure than the first pressure range.

[0190] S20. A cooling system (10) according to one of the above embodiments having the features of embodiment S19, wherein the second compressor (14) is configured to compress the refrigerant from a secondary pressure range to a tertiary pressure range, the tertiary pressure range having a higher pressure than the secondary pressure range.

[0191] S21. A cooling system (10) according to one of the above embodiments having the features of embodiment S12, comprising a further expansion device (46) arranged in the return section, the further expansion device (46) being configured to reduce the refrigerant from the tertiary pressure range to the secondary pressure range.

[0192] S22. A cooling system (10) according to one of the above embodiments having the features of embodiments S12 and S21, wherein a further expansion device (46) is arranged upstream of the secondary side of the heat exchanger (48) and / or downstream of the connection point (42).

[0193] S23. A cooling system (10) according to one of the above embodiments having the features of embodiment S6 with a separate heat exchanger (50), wherein the separate heat exchanger (48) has a primary side arranged in the main circuit upstream of the expansion device (18) and / or downstream of the cooling component (16), the separate heat exchanger (50) being configured to cool a refrigerant.

[0194] S24. A cooling system (10) according to one of the above embodiments having the features of embodiments S14 and S23, wherein another heat exchanger (48) is arranged downstream of the primary side of the heat exchanger (48) in the main circuit.

[0195] S25. A cooling system (10) according to one of the above embodiments having the features of embodiment S23, wherein a further heat exchanger (50) comprises a secondary side arranged downstream of the evaporator (11) and / or upstream of the first compressor (12), the further heat exchanger (50) being configured to absorb heat from the refrigerant by means of the primary side and to release the absorbed heat to the refrigerant by means of the secondary side to heat the refrigerant upstream of the first compressor (12).

[0196] S26. A cooling system (10) according to one of the above embodiments having the features of embodiment S23, wherein the further heat exchanger (50) is a pipe-to-pipe heat exchanger.

[0197] S27. A cooling system (10) according to one of the above embodiments, which may be provided with a liquid separator (30) configured to separate the refrigerant in a liquid state, the liquid separator (30) being arranged in the main circuit downstream of the evaporator (11) and / or upstream of the first compressor (12).

[0198] S28. A cooling system (10) according to one of the above embodiments having the features of embodiment S25, wherein the liquid separator (30) is arranged upstream of the secondary side of the further heat exchanger (50).

[0199] S29. A cooling system (10) according to one of the above embodiments comprising a filter dryer (34) configured to remove moisture from the refrigerant, the filter dryer (34) being positioned in the main circuit downstream of the refrigeration component (16) and / or upstream of the expansion device (18).

[0200] S30. A cooling system (10) according to one of the above embodiments having the features of embodiments S14, S23 and S29, wherein the filter dryer (34) is arranged in the main circuit between the primary side of the heat exchanger (48) and the primary side of the further heat exchanger (50).

[0201] S31. A cooling system (10) according to one of the above embodiments having the features of embodiments S12 and S29, wherein a filter dryer (34) is arranged downstream of the connection point (42).

[0202] S32. A cooling system (10) according to one of the above embodiments comprising an intermediate pressure vessel (70) configured to separate the refrigerant into a liquid phase and a gas phase, the intermediate pressure vessel (70) being arranged in the main circuit downstream of the cooling component (16) and / or upstream of the expansion device (18).

[0203] S33. A cooling system (10) according to one of the above embodiments having the features of embodiments S23 and S32, wherein the intermediate pressure vessel (70) is formed as a three-way collector; and a vessel inlet (71) configured to direct the refrigerant into the intermediate pressure vessel (70) and arranged downstream of the cooling component (16); a first vessel outlet (72) configured to direct liquid refrigerant from the intermediate pressure vessel to the piping section (208) and positioned upstream of the evaporator (11) and / or upstream of the expansion device (18); a second vessel outlet (73) configured to couple the intermediate pressure vessel (70) to the return section (40) and to direct gaseous refrigerant to the return section (40).

[0204] S34. A cooling system (10) according to one of the above embodiments having the features of embodiments S6, S14 and S33, wherein the container inlet (71) is arranged downstream of the heat exchanger (48) in the main circuit.

[0205] S35. A cooling system (10) according to one of the above embodiments having the features of embodiments S29 and S33, wherein the vessel inlet (71) is arranged downstream of the filter dryer (34).

[0206] S36. A cooling system (10) according to one of the above embodiments having the features of embodiments S12 and S32, wherein the first connection point (42) is formed by the intermediate pressure vessel (70).

[0207] S37. A cooling system (10) according to one of the above embodiments comprising a high pressure control device (74), the high pressure control device being configured to reduce the pressure of the refrigerant, in particular to reduce the pressure from a tertiary pressure range to a secondary pressure or to reduce the pressure within the tertiary pressure range.

[0208] S38. A cooling system (10) according to the above embodiments and having the features of embodiment S32, wherein the high pressure control device (74) is disposed upstream of the intermediate pressure vessel (70).

[0209] S39. A cooling system (10) according to one of the two above embodiments and having the features of embodiments S14 and S29, wherein the high-pressure control device (74) is arranged in the main circuit downstream of the cooling component (16), the first heat exchanger (48) and / or the filter-drier (34).

[0210] S40. A cooling system (10) according to one of the above embodiments having the features of embodiment S37, wherein the high pressure control device (74) is controllable based on pressure, in particular based on the pressure of the refrigerant downstream of the cooling component (16).

[0211] S41. A cooling system (10) according to one of the above embodiments having the features of embodiments S12 and S37, wherein the high pressure controller (74) is controllable based on the pressure downstream of the first heat exchanger (48) and / or upstream of the high pressure controller (74).

[0212] S42. A cooling system (10) according to one of the above embodiments having the features of embodiments S29 and S37, wherein the high pressure controller (74) is controllable based on the pressure upstream of the filter dryer (34).

[0213] S43. A cooling system (10) according to one of the above embodiments, wherein the expansion device (18) is a superheat control device and is configured to control the superheat of the refrigerant in the evaporator (11).

[0214] S44. A cooling system (10) according to one of the above embodiments having the features of embodiment S43, wherein the expansion device (18) is configured to regulate the pressure of the refrigerant, in particular to reduce the pressure of the refrigerant from a secondary pressure range to a primary pressure range or from a tertiary pressure range to a primary pressure range.

[0215] S45. A cooling system (10) according to one of the above embodiments, wherein the expansion device (18) is controllable based on pressure, in particular based on the pressure of the refrigerant downstream of the evaporator (11) and / or upstream of the first compressor (12).

[0216] S46. A cooling system (10) according to one of the above embodiments having the features of embodiment S23, wherein the expansion device (18) is adjustable based on the pressure upstream of the further heat exchanger (50).

[0217] S47. A cooling system (10) according to one of the above embodiments having the features of embodiment S32, wherein the expansion device (18) is controllable based on parameter values ​​of the intermediate pressure vessel (70) to control the flow of refrigerant from the piping section (208) to the piping section (210).

[0218] S48. A cooling system (10) according to one of the above embodiments having the features of embodiment S47, wherein the parameter is a filling level, a pressure, a temperature and / or a condensation state of the refrigerant in the medium pressure vessel.

[0219] S49. A cooling system (10) according to one of the above embodiments having the features of embodiment S47, wherein the expansion device (18) is configured to detect a parameter value of the intermediate pressure vessel (70).

[0220] S50. A cooling system (10) according to one of the above embodiments comprising a second cooling component (32), the second cooling component being configured to cool a refrigerant and being positioned downstream of the first compressor (12) and / or upstream of the second compressor (14).

[0221] S51. A cooling system (10) according to one of the above embodiments having the features of embodiments S12 and S50, wherein the second cooling component (32) is arranged upstream of the connection point (44).

[0222] S52. A cooling system (10) according to one of the above embodiments having the features of embodiment S50, wherein the second cooling component (32) is configured to cool the refrigerant to provide the refrigerant at the outlet of the second cooling component (32) in gaseous form, within a secondary pressure range, and at a reduced temperature when the refrigerant exceeds ambient temperature.

[0223] S53. A cooling system (10) according to one of the above embodiments having the features of embodiment S50, wherein the second cooling component (32) is configured to cool the refrigerant to a predetermined temperature, whereby the refrigerant downstream of the second compressor (14) has a temperature below the threshold temperature.

[0224] S54. A cooling system (10) according to one of the above embodiments having the features of embodiment S53, wherein the limit temperature is determined such that the refrigerant has a subcritical temperature.

[0225] S55. A cooling system (10) according to one of the above embodiments having the features of embodiment S50, wherein the second cooling component (32) is configured such that the second cooling component (32) is provided with a ventilator, the ventilator being configured to generate an air flow in the second cooling component (32) to remove heat from the refrigerant.

[0226] S56. A cooling system (10) according to one of the above embodiments having the features of embodiments S32 and S50, wherein the second vessel outlet (73) is connected to the second cooling component (32) via a piping section (216).

[0227] S57. A cooling system (10) according to one of the above embodiments having the features of embodiment S56, wherein a first refrigerant stream flows from the second cooling component (32) to another connection point (52), and a second refrigerant stream flows from the second container outlet (73) to another connection point (52), and the first refrigerant stream and the second refrigerant stream are mixed to form a combined refrigerant stream at the another connection point (52), and the mixed refrigerant stream flows via the piping section (214) to the second connection point (44) and / or the second compressor (14).

[0228] S58. A cooling system (10) according to one of the above embodiments having the features of embodiment S12, wherein the refrigerant from the return section (40) can be injected into the piping (204) via a second connection point (44) in a secondary pressure range.

[0229] S59. A cooling system (10) according to one of the above embodiments having the features of embodiments S14 and S50, wherein the heat exchanger (48) is configured to provide a refrigerant at the second connection point (44) with a first specific enthalpy, and the second cooling component (32) is configured to provide a refrigerant at the second connection point (44) with a second specific enthalpy, the first specific enthalpy being less than the second specific enthalpy.

[0230] S60. A cooling system (10) according to one of the above embodiments having the features of embodiment S12, wherein the refrigerant flow in the return section (40) and another refrigerant flow in the pipe (214) at the second connection point (44) are mixed to form a combined refrigerant flow, and the combined refrigerant flow is provided to the second compressor (14).

[0231] S61. A cooling system (10) according to one of the above embodiments having the features of embodiment S50, wherein the second cooling component (32) is configured to cool the refrigerant based on the ambient temperature and / or based on a limit temperature of the evaporator (11).

[0232] S62. A cooling system (10) according to one of the above embodiments comprising a circuit controller configured to control the flow of refrigerant.

[0233] S63. A cooling system (10) according to one of the above embodiments having the features of embodiment S62, wherein the circuit controller is configured to control the opening of the expansion device (18) based on the pressure of the refrigerant, in particular the high pressure downstream of the cooling component (16) and / or downstream of the second compressor (14), and is capable of controlling the decompression of the refrigerant downstream of the expansion device (18) depending on the opening degree of the expansion device (18).

[0234] S64. A cooling system (10) according to one of the above embodiments having the features of embodiments S14 and S62, wherein the circuit controller is configured to control the opening of the expansion device (18) based on the pressure of the refrigerant downstream of the heat exchanger (48).

[0235] S65. A cooling system (10) according to one of the above embodiments having the features of embodiment S62, wherein the expansion device (18) has a valve and is configured to adapt the opening of the valve in a stepwise or continuous manner in a range from fully closed to fully open under the control of the circuit controller.

[0236] S66. A cooling system (10) according to one of the above embodiments having the features of embodiment S62, wherein the circuit controller is configured to control the opening of the expansion device (18) based on the temperature of the refrigerant upstream of the first compressor (12) and / or downstream of the evaporator (11), in particular the temperature at the evaporator outlet.

[0237] S67. A cooling system (10) according to one of the above embodiments, wherein the pressure relief of the refrigerant downstream of the expansion device (18) is controllable depending on the opening degree of the expansion device (18).

[0238] S68. A cooling system (10) according to one of the above embodiments having the features of embodiment S62, wherein the circuit controller is configured to determine a predetermined temperature value and to control the opening of the expansion device (18) when the detected temperature, in particular the evaporator outlet temperature, exceeds the predetermined temperature value.

[0239] S69. A cooling system (10) according to one of the above embodiments having the features of embodiments S21 and S62, wherein the circuit controller is configured to control the opening of the further expansion device (46) depending on the temperature of the refrigerant downstream of the first compressor (12) and / or downstream of the second compressor (14), in particular the compressor outlet temperature or the hot gas temperature, and is capable of controlling the decompression of the refrigerant downstream of the further expansion device (46) depending on the opening degree of the further expansion device (46).

[0240] S70. A cooling system (10) according to one of the above embodiments having the features of embodiments S37 and S62, wherein the circuit controller is configured to control the opening of the high pressure control device (74) depending on the pressure of the refrigerant downstream of the second compressor (14) and / or upstream of the high pressure control device (74).

[0241] S71. A cooling system (10) according to one of the above embodiments having the features of embodiments S14, S29 and S70, wherein the circuit controller is configured to control the high pressure control device (74) in response to the pressure downstream of the heat exchanger (48) and / or upstream of the filter dryer (34).

[0242] S72. A cooling system (10) according to one of the above embodiments comprising a compressor drive device, the compressor drive device being configured to drive the first compressor (12) and / or the second compressor (14).

[0243] S73. A cooling system (10) according to one of the above embodiments having the features of embodiment S72, wherein the compressor drive device is configured to control a compressor speed of each of the first compressor (12) and / or the second compressor (14) depending on the pressure of the refrigerant downstream of the expansion device (18), in particular the evaporation pressure, and / or the temperature of the refrigerant, in particular the evaporation temperature, and the compression capacity of the first compressor (12) and / or the second compressor (14) is controllable depending on the compressor speed.

[0244] S74. A cooling system (10) according to one of the above embodiments having the features of embodiments S62 and S72, wherein the first compressor (12), the second compressor (14) and / or the compressor drive device each have a drive device and are configured to adapt the rotation speed of each drive device stepwise or continuously within a predetermined range from a minimum rotation speed to a maximum rotation speed under control of the circuit controller.

[0245] S75. A cooling system (10) according to one of the above embodiments having the features of embodiment S62, wherein the circuit controller is configured to control the compressor speed based on a predetermined evaporating temperature.

[0246] S76. A cooling system (10) according to one of the above embodiments having the features of embodiment S62, wherein the circuit controller is configured to increase the compressor speed to reduce the evaporating temperature and / or to decrease the compressor speed to reduce the evaporating temperature.

[0247] S77. A cooling system (10) according to one of the above embodiments, wherein the cooling component (16) comprises a ventilator configured to pass an air flow through the cooling component (16) for cooling.

[0248] S78. A cooling system (10) according to one of the above embodiments, wherein the cooling component (16) comprises a refrigerant bleed pipe heat exchanger configured to transfer heat from the refrigerant to the bleed pipe.

[0249] S79. A cooling system (10) according to one of the above embodiments having the features of embodiments S62 and S77, wherein the circuit controller is configured to control the fan speed of the ventilator depending on the temperature of the refrigerant downstream of the cooling component (16), in particular the cooling component outlet temperature, and is capable of controlling the cooling capacity of the cooling component (16) depending on the fan speed.

[0250] S80. A cooling system (10) according to one of the above embodiments having the features of embodiments S62 and S77, wherein the ventilator is configured to adapt the ventilator speed in a stepwise or continuous manner within a predetermined range from a minimum speed to a maximum speed under control of the circuit controller.

[0251] S81. A cooling system (10) according to one of the above embodiments having the features of embodiments S62 and S77, wherein the circuit controller is configured to control the ventilator in a number of stages depending on the thermal load, where in a first control stage the ventilator rotation speed is zero, in a second control stage the ventilator rotates at a first rotation speed greater than zero, and / or in a third control stage the ventilator rotates at a second rotation speed, the second rotation speed being greater than the first rotation speed.

[0252] S82. A cooling system (10) according to one of the above embodiments having the features of embodiment S62, wherein the circuit controller is configured to control the pressure in a tertiary pressure range so that cooling capacity is maximized.

[0253] S83. A cooling system (10) according to one of the above embodiments having the features of embodiment S62, wherein the circuit controller is configured to control the superheat of the evaporator (11) by the expansion device (18) so as to minimize heating, the superheat being in particular at least 3 K at the compressor inlet.

[0254] S84. A cooling system (10) according to one of the above embodiments having the features of embodiments S21 and S62, wherein the circuit controller is configured to control the compressor outlet temperature in the first compressor (12) and / or the second compressor (14) respectively by means of a separate expansion device (46) so as to be below a predetermined limit temperature at the compressor outlet.

[0255] S85. A cooling system (10) according to one of the above embodiments having the features of embodiment S12, wherein cooled refrigerant from the return section (44) can be injected at the second connection point (44) to reduce the compressor outlet temperature.

[0256] S86. A cooling system (10) according to one of the above embodiments having the features of embodiment S62, wherein the circuit controller is configured to steplessly control the first compressor speed of the first compressor and the second compressor speed of the second compressor, respectively, and the circuit controller is configured to separately control the first compressor speed and the second compressor speed, respectively.

[0257] S87. A cooling system (10) according to one of the above embodiments having the features of embodiment S62, wherein the circuit controller is configured to accelerate the first compressor and / or the second compressor to a respective predefined target speed with a respective predefined acceleration value during the start-up phase, the acceleration being in particular 8 revolutions / s 2 Below is the cooling system.

[0258] S88. A cooling system (10) according to one of the above embodiments having the features of embodiments S77 and S87, wherein the circuit controller is configured to control, in particular to control steplessly, the ventilator speed depending on the acceleration of the first compressor and / or the acceleration of the second compressor.

[0259] S89. A cooling system (10) according to one of the above embodiments having the features of embodiment S88, wherein the control characteristic curve of the ventilator precedes the control characteristic curve of the first compressor and / or the second compressor.

[0260] S90. A cooling system (10) according to one of the above embodiments having the features of embodiments S62 and S77, wherein the circuit controller is configured to control the ventilator speed of the ventilator depending on the ambient temperature, in particular proportional to the ambient temperature, the ambient temperature being detectable at the air outlet of the laboratory equipment, in particular the cooling component.

[0261] S91. A cooling system (10) according to one of the above embodiments having the features of embodiment S62, wherein the circuit controller is configured to control the expansion device depending on the outlet temperature of the cooling component and / or the ambient temperature in order to regulate the pressure in a tertiary pressure range, in particular to an optimal high pressure.

[0262] S92. A cooling system (10) according to one of the above embodiments having the features of embodiment S91, wherein the expansion device comprises a thermostatic valve or an electronic expansion valve.

[0263] S93. A cooling system (10) according to one of the above embodiments having the features of embodiment S62, wherein the circuit controller is configured to detect a change in ambient temperature and to control the expansion device, the compressor speed, and / or the ventilator speed based on the change in ambient temperature.

[0264] Below are listed embodiments of laboratory equipment. These embodiments are abbreviated by the letter "L" followed by a number. Hereinafter, these embodiments are meant whenever reference is made to "laboratory equipment embodiments."

[0265] L1. Laboratory equipment with cooling system (300).

[0266] L2. A laboratory instrument according to the above embodiments, wherein a cooling system according to one of the above system embodiments is formed.

[0267] L3. The laboratory equipment according to the above embodiments, wherein the laboratory equipment is a centrifuge, and / or the laboratory equipment is a benchtop or floor-standing equipment.

[0268] L4. A laboratory equipment according to one of the above embodiments, wherein the laboratory equipment comprises a rotor tank (301), in which one / the aforementioned evaporator (11) is arranged.

[0269] L5. An experimental apparatus according to one of the above embodiments having the features of embodiment L4, wherein the evaporator arranged on the outer surface of the rotor tank comprises an evaporator winding (302), the evaporator winding being formed by a circumferential piping.

[0270] L6. An experimental device according to one of the above embodiments having the features of embodiment L5, wherein the evaporator winding has a shape, in particular a D-shape, flattened on at least one side to form a flat surface, which abuts against the outer surface of the rotor tank to form an area contact.

[0271] L7. An experimental device according to one of the above embodiments having the features of embodiment L6, wherein the evaporator winding has an outer tube diameter in the range of 5 mm to 20 mm, in particular 10 mm or 16 mm, and / or the evaporator winding has a wall thickness of 0.5 mm to 5 mm, in particular 1 mm.

[0272] L8. A laboratory apparatus according to one of the above embodiments having the features of embodiment L4, wherein the rotor tank has a side mantle surface, a bottom mantle surface and a bottom surface, the side mantle surface being formed cylindrically and the bottom mantle surface having a curved contour and being formed to connect the side mantle surfaces with the bottom surface.

[0273] L9. A laboratory device according to one of the above embodiments having the features of embodiments L5 and L8, wherein the evaporator windings are arranged on the side mantle surface, the bottom mantle surface, and / or the bottom surface.

[0274] L10. An experimental device according to one of the above embodiments having the features of embodiments L5 and L8, wherein the evaporator winding forms surface contacts at the lateral mantle surfaces.

[0275] The present invention will now be described with reference to the accompanying drawings, in which embodiments of the invention are shown by way of example and not by way of limitation. [Brief description of the drawings]

[0276] [Figure 1A] 1 shows a schematic diagram of a cooling system according to one embodiment. [Figure 1B] 1B shows an enthalpy-pressure diagram of the cycle of an embodiment of the cooling system according to FIG. 1A. [Figure 2A] 1 shows a schematic diagram of a cooling system according to one embodiment. [Figure 2B] 2B shows an enthalpy-pressure diagram for the cycle of an embodiment of the cooling system according to FIG. 2A. [Figure 3A] 1 shows a schematic diagram of a cooling system according to one embodiment. [Figure 3B] 3B shows an enthalpy-pressure diagram for the cycle of an embodiment of the cooling system according to FIG. 3A. [Figure 4A] 1 shows a schematic diagram of a cooling system according to one embodiment. [Figure 4B] 4B shows an enthalpy-pressure diagram for the cycle of an embodiment of the cooling system according to FIG. 4A. [Figure 5A]1 shows a schematic diagram of a cooling system according to one embodiment. [Figure 5B] 5B shows an enthalpy-pressure diagram for the cycle of an embodiment of the cooling system according to FIG. 5A. [Figure 6A] 1 shows a schematic diagram of a cooling system according to one embodiment. [Figure 6B] 6B shows an enthalpy-pressure diagram for the cycle of an embodiment of the cooling system according to FIG. 6A. [Figure 7] 1 shows a schematic diagram of a cooling system according to one embodiment. [Figure 8] FIG. 2 shows a schematic cross-sectional view of a rotor tank according to one embodiment. [Figure 9A] FIG. 2 illustrates a perspective cross-sectional view of a rotor tank according to one embodiment. [Figure 9B] FIG. 2 illustrates a perspective cross-sectional view of a rotor tank according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0277] It should be noted that not all reference numbers are included in all drawings, and instead, some reference numbers are omitted in some drawings for brevity and ease of illustration. Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0278] An embodiment of the present invention allows for an efficient use of CO2 as a refrigerant in a cooling system, in particular designed for heat dissipation in laboratory equipment 300, especially in centrifuges. In this case, the operating mode of the cooling system can be optimized by the heat flow and / or the refrigerant flow in addition to the main circuit, and the efficiency of the cooling system can be increased accordingly.

[0279] Each of the variants A and B in Figures 1 to 6 forms a unit of a schematic circuit diagram and a corresponding log-p enthalpy diagram, where the process points representing the state of the refrigerant are shown as numbers marked with rectangles in the circuit diagram and the log-p enthalpy diagram.

[0280] The specific enthalpy of the refrigerant used (CO2) is plotted on the x-axis (see for example FIG. 1B) and the pressure is plotted on the y-axis, which is logarithmic. The diagram has a bell-shaped line, the left-hand region of which is labeled 802 and the right-hand region is labeled 804.

[0281] In the region bounded by the bell-shaped lines 802, 804, i.e., as shown, located below the lines 802, 804, the refrigerant exists as a wet vapor, i.e., a mixture of liquid and gaseous states. To the left of the line region 802, the refrigerant is in the liquid phase, and the line region 802 is also referred to as the boiling line. To the right of the line region 804, the refrigerant is in the gas phase, and the line region 804 is also referred to as the dew line.

[0282] The boiling line 802 and the dew line 804 meet at the critical point, above which (i.e., at pressures above the critical pressure) the gas and liquid phases cannot be distinguished, and this region is also called the supercritical region.

[0283] In the diagram of Figure 1B, a line represents a diagram illustrating a cooling process according to an embodiment of the present invention, which can be used in the embodiment of Figure 1a.

[0284] The refrigeration system may have multiple sensors 60 configured to detect pressure and / or temperature, respectively. Accordingly, the temperature and pressure may be determined at different locations within the system 10. In Figures 1A and 1B, a two-stage compression refrigeration system is shown.

[0285] The cooling system 10 is also simply referred to as the system 10. The system 10 comprises the following: an evaporator 11, a first compressor 12, a second compressor 14, a first cooling component 16, and a first expansion device 18, which may be formed, for example, as an expansion valve 18, hereinafter also simply referred to as the expansion valve 18. In one embodiment, the first compressor 12 and the second compressor may be arranged in one housing, in particular in a common housing. For the first compressor 12 and the second compressor 14, a common drive may be provided, which is formed to drive both the first compressor 12 and the second compressor 14.

[0286] Additionally, the cooling system 10 includes a piping system 20 that includes a number of pipings 20', 21' that connect the other components of the system 10 to one another, where the letter ' represents a number.

[0287] The system 10 includes an evaporator 11, a first compressor 12, a second compressor 14, a cooling component 16, and an expansion valve 18 connected to each other in this order, forming a first circuit, also called a main circuit, with the evaporator 11 again connected to the expansion valve 18. In particular, the first compressor 12 and the second compressor 14 are arranged between the evaporator 11 and the cooling component 16 and are arranged in series with each other.

[0288] Additionally, the system 10 includes a filter dryer 34 disposed between the first refrigeration component 16 and the expansion valve 18. The filter dryer 34 may be located upstream of the expansion device 18 in the main circuit.

[0289] The terms "upstream" and "downstream" are used in several places in this document. For example, in view of Figure 1a, it should be apparent that the refrigerant flows counterclockwise, such that the expansion device 18 is located downstream of the filter dryer 34.

[0290] At the same time, it should be noted that the process used is a cyclical process: after the refrigerant leaves the expansion device 18, it passes after a certain time through the compressor 11, the two compressors 12 and 14, the cooling component 16 and then back again to the filter-drier 34.

[0291] However, it should be understood that the process technological connection from the filter dryer 34 to the expansion device 18 is shorter than from the expansion device 18 (via another element) to the filter dryer 34. Therefore, in this document, for the terms "upstream" and "downstream", the shorter process technological connection between the two elements is taken into account. Thus, as mentioned above, for example, the expansion device 18 is arranged downstream of the filter dryer 34 and the evaporator 11 is arranged downstream of the expansion device 18. Another example is a second compressor 14 arranged downstream of the evaporator 11.

[0292] If in this document it is stated that an element is arranged between two other elements, this refers to an arrangement between the process-technically shorter connections of the other elements. In the exemplary embodiment shown in FIG. 1A, in this sense the first compressor 12 is arranged, for example, between the evaporator 11 and the second compressor 14.

[0293] The first compression can be accomplished by the first compressor 12 and the second compression can be accomplished by the second compressor 14 to bring the refrigerant from a low pressure at the outlet of the evaporator 11 to a high pressure at the outlet of the second compressor 14. The cooling component 16 provides enthalpy reduction to remove the heat absorbed in the compressor 11 from the system 10. This cooling can transition the refrigerant from a gas phase to a liquid phase. The expansion device 18 then transitions the refrigerant from the liquid phase to a wet vapor phase through a pressure reduction so that it can be provided to the evaporator for heat absorption.

[0294] With reference to Figures 1A and 1B, the refrigeration circuit can be described as follows: The process points are uniformly indicated by numbers in rectangles in the corresponding Figures A and B, respectively. Process point 1 is located downstream of the evaporator 11 and upstream of the first compressor 12. At this process point 1, the refrigerant is in gaseous form and exists at a relatively low temperature and a relatively small pressure.

[0295] At process point 2, located between first compressor 12 and second compressor 14, the refrigerant is in gaseous form and at medium pressure and temperature.

[0296] At process point 3, located between second compressor 14 and cooling component 16, the refrigerant is at high pressure and high temperature. In the examples shown, the refrigerant is supercritical at this process point 3. However, it should be noted that this is not necessary and that at process point 3 the refrigerant can also be present in gaseous form. Thus, in these embodiments, in the diagram according to FIG. 1B, process point 3 (or generally the process point between second compressor 14 and cooling component 16) is located below the critical pressure in terms of pressure, which also applies to the other examples.

[0297] The refrigerant is cooled by the cooling component 16, so that it is present at high pressure and low temperature at process point 4, which is located between the cooling component 16 and the expansion device 18. In the illustrated exemplary embodiment, the refrigerant is supercritical at process point 4. However, it is also possible in this case for the refrigerant to be present in another phase, in particular as wet vapor, at this process point 4 (or at a process point between the cooling component 16 and the expansion device 18 in general). In such an embodiment, again in the phase diagram according to FIG. 1B, at the corresponding process point (here: process point 4), the pressure is below the critical pressure, which is also possible in the embodiments described below.

[0298] The refrigerant may then be expanded through expansion device 18 so that it exists as a wet vapor at process point 5 between expansion device 18 and evaporator 11 at low pressure and temperature.

[0299] The refrigerant can then be evaporated by the evaporator 11 so that the refrigerant exists at process point 1 at low pressure and low temperature between the evaporator 11 and the first compressor 12. In the example shown, the refrigerant is in gaseous form at process point 1.

[0300] The embodiment shown in Figures 2A and 2B adds (i.e. further comprises) a liquid separator 30 arranged between the evaporator 11 and the first compressor 12 to the cooling system according to Figures 1A and 1B.

[0301] In addition to the circuits described, the system 10 further comprises a return section 40, which is fluidly connected to the circuits at two connections, also referred to simply as connections, 42 and 44. The first connection 42 is provided between the first refrigeration component 16 and the expansion valve 18, and the second connection 44 is provided between the first compressor 12 and the second compressor 14.

[0302] The return section 40 further comprises an expansion device 46 (also called an expansion valve 46) and passes through a heat exchanger 48 through which also passes the piping 208 connecting the above-mentioned circuit, in particular the cooling component 16 with the expansion valve 18.

[0303] The system 10 comprises another heat exchanger 50 which is flowed through on the one hand by a line 208 and on the other hand by a line 202 which connects the evaporator 11 with the first compressor 12 .

[0304] The further expansion device 46 can be adjusted depending in particular on the high pressure and / or the hot gas temperature at the outlet of the second compressor 14. The refrigerant flow rate through the return section 40 can thus be reduced or increased, with the hot gas temperature being reduced or increased accordingly. Furthermore, the further expansion device 46 can realize a post-expansion of the refrigerant in the high pressure region. Thereby, a refrigerant with a lower enthalpy (for example according to process point 8 in FIG. 2A / FIG. 2B) can be mixed with a refrigerant with a higher enthalpy (for example according to process point 2 in FIG. 2A / FIG. 2B). By mixing at the second connection point 44 and / or flowing through the heat exchanger 48, the enthalpy can be increased, and wet suction, i.e. suction of a refrigerant partially in liquid phase and / or in wet vapor phase in front of the second compressor 14, is avoided or at least the possibility of wet suction is reduced.

[0305] The expansion device 18 may be adjusted in response to the pressure and / or temperature at the outlet of the heat exchanger 48. In this case, this pressure at the outlet of the heat exchanger may be substantially the same as the pressure at the inlet of the expansion device 18.

[0306] Looking at the phase diagram in FIG. 2B, one can first basically refer to the description of the phase diagram in FIG. 1B, and it should be understood by those skilled in the art that the process points (taking into account the following supplementary matters) are substantially as follows: [Table 1]

[0307] 2A, 2B has a return section 40 in addition to the main circuit. Furthermore, this embodiment also has, among other things, a heat exchanger 48 arranged downstream of the cooling component 16. The refrigerant downstream of the cooling component 16 is further cooled by the heat exchanger 48, so that the refrigerant downstream (at process point 6) is at an even lower temperature than at process point 5.

[0308] Further downstream in the main circuit is another heat exchanger 50 which further cools the refrigerant so that it exists downstream at process point 9 (FIGS. 2A / 2B) at an even lower temperature.

[0309] The refrigerant can then be expanded again as described above through expansion valve 18 and thus exists as a wet vapor at process point 10.

[0310] The refrigerant can again be evaporated by the evaporator 11. However, the evaporation may not take place completely, so that the refrigerant is close to the dew line just downstream of the evaporator (process point 11, FIG. 2A / FIG. 2B) and liquid components are present in the refrigerant. Such liquid can be separated by a liquid separator 30 arranged downstream of the evaporator 11, and additional energy can be introduced into the refrigerant between the evaporator 11 and the first compressor 12 by the already described heat exchanger 50, so that the refrigerant is in gaseous form at process point 1.

[0311] The return section 40 is arranged between the connection points 42 and 44. In the return section 40 downstream of the connection point 42, an expansion device 46, which may be formed, for example, as an expansion valve, is arranged. Downstream therefrom, at process point 7, the refrigerant is present as wet vapor at medium pressure and at a relatively low temperature. The refrigerant can be heated by means of a heat exchanger 48. In the embodiment shown here, the refrigerant is heated to the dew point, but it is also possible that the refrigerant is present downstream of the heat exchanger 48 (i.e. at process point 8) as wet vapor or in gaseous form. Overall, the system is operated such that the specific enthalpy resulting from the mixing of the refrigerants at the connection 44 (i.e. at process point 3) is suitable for further cycle processes.

[0312] The use of the return section 40 thus provides, overall, a late injection of refrigerant, thereby making it possible to adjust the hot gas temperature at the outlet of the second compressor 14. This allows different heat loads to be taken into account.

[0313] The use of post-injection and one or more internal heat exchangers can increase the Coefficient of Performance (COP), which can be defined as the ratio of cooling capacity to power, specifically to the power consumed.

[0314] Post-injection can shift process point 4 on the log(p)-h diagram (FIGS. 3A / 3B) further to the left, i.e., in the direction of lower enthalpy. Furthermore, it can be seen that the refrigerant passing through heat exchanger 48 at process point 7 has a lower enthalpy than at process point 6, such that after the isenthalpic (i.e., vertical in FIG. 3B) pressure relief between process points 11 and 12, the refrigerant exits at process point 12 at a lower enthalpy than it would if no heat exchanger were provided.

[0315] The heat exchanger 48 can be configured, for example, as an economizer heat exchanger, which is arranged before the valve 18 and thus allows the temperature of the refrigerant to be further subcooled. This can result in a larger specific evaporation capacity q and thus a smaller required mass flow rate and, as a result, a lower compressor speed. It is thus possible to adapt and increase the required evaporation capacity by means of post-injection.

[0316] Another embodiment of the present invention is described with reference to Figures 3A and 3B. The system 10 further includes a second refrigeration component 32 disposed between the first compressor 12 and the second compressor 14.

[0317] The diagram of Figure 3b shows a cooling process that may be used by the cooling system 10 according to the embodiment shown in Figure 3A. The reference numbers 1 to 13 shown in rectangular boxes correspond to each other in Figures 10a and 10b.

[0318] The state of the refrigerant at different points can be summarized as follows: [Table 2]

[0319] In some embodiments, the refrigerant may be in gaseous form at process point 5. Alternatively, or in addition, the refrigerant may be in liquid form at process points 6, 7, 10, and 11.

[0320] Looking at the refrigerant at process point 1 (see Figures 3a and 3b), ie upstream of the first compressor 12, the refrigerant is in gaseous form and exists at low pressure and temperature.

[0321] The refrigerant is compressed in the first compressor 12 so that it is in gaseous form and at intermediate pressure downstream of the first compressor 12 (i.e., at process point 2). The compression also heats the refrigerant so that it is at intermediate temperature.

[0322] In the cooling component 32, the refrigerant is cooled so that downstream thereof (process point 3) it is present in gaseous form, at medium pressure and low temperature (i.e. at a lower temperature than process point 2), for example at about 28° C. The cooling component 32 may be provided especially in the case of relatively high evaporation temperatures.

[0323] This refrigerant is mixed with the refrigerant from the return section 40, which is at an even lower temperature, so that at process point 4, which is between the connection 44 and the second compressor 14, the refrigerant is in gaseous form and is at medium pressure and low temperature, which is even lower than at process point 3.

[0324] In the second compressor 14 the refrigerant is further compressed. In particular, the compression is carried out here in such a way that the refrigerant can be compressed above the critical pressure (see FIG. 3b), i.e. downstream of the second compressor 14 at process point 5 the refrigerant is supercritical and present at high pressure (it is also possible in an embodiment of the invention that the refrigerant at process point 5 is present in gaseous form). Furthermore, the compression also heats the refrigerant, so that it is present at high temperature.

[0325] The refrigerant is cooled by the cooling component 16. Thus, downstream of the cooling component, at process point 6, the refrigerant is supercritical (in another possible embodiment, liquid), at high pressure and at low temperature (which is lower than at process point 5).

[0326] The refrigerant may be further cooled by heat exchanger 48. Thus, downstream of heat exchanger 48, at process point 7, the refrigerant is supercritical (in some embodiments, liquid state), at high pressure and low temperature (which is lower than at process point 6).

[0327] Continuing first along the main circuit, the refrigerant downstream of process point 6 is conducted through a filter dryer 34 which has no or only a negligible effect on the quantities of state of the refrigerant, so that the conditions downstream of the dryer 34, at process point 10, are at least substantially the same as those at process point 7. A minimal pressure loss may occur through the filter dryer 34, but this is negligible relative to the pressure changes through the expansion device 11 and compressors 12, 14. The filter dryer 34 may also be located downstream of another heat exchanger 50 in the main circuit.

[0328] In the illustrated embodiment, the refrigerant is further cooled downstream of the filter dryer 34 by heat exchanger 50, such that it exists downstream of the heat exchanger 50 (process point 11) in a supercritical (in some embodiments, gaseous) state, at a high pressure and low temperature (even lower than process points 7 and 10).

[0329] Further down in the process, the refrigerant passes through expansion valve 18, where it expands and is transformed into a wet vapor. Thus, downstream of expansion valve 18 (i.e., at process point 12), the refrigerant exists as a wet vapor at a reduced pressure and a reduced temperature.

[0330] The refrigerant is then evaporated by the evaporator 11, i.e. ideally, completely transferred to a gaseous state. That is, downstream of the evaporator 11 (i.e., process point 13), the refrigerant is in gaseous state (or in the transition between wet vapor and gaseous state in FIG. 10b) and exists at low pressure and low temperature. Unlike ideal evaporation, the evaporator can bring the refrigerant at least partially close to the dew line 804 or even exactly to the dew point. In this case, the liquid component of the refrigerant can be separated and / or converted to gaseous refrigerant by the liquid separator 30 and / or another heat exchanger 50.

[0331] A liquid separator 30 can be provided downstream of the evaporator 11 to at least partially remove the liquid components and ensure that they do not reach the components arranged downstream, in particular the compressors 12, 14. In this case, for example, the liquid components can be reduced so that the formation of liquid droplets at the compressor inlet is prevented or at least reduced.

[0332] Furthermore, downstream of the evaporator 11 and upstream of the first compressor 12, the refrigerant can pass through the already described heat exchanger 50 and be heated thereby, so that downstream, at process point 1, the refrigerant is in gaseous form and is present at low pressure and low temperature (but warmer than at process point 13), thereby completing the process cycle. This makes it possible to further ensure that no, or as little as possible, refrigerant in liquid state reaches the compressor 12 arranged downstream, especially in the case of incomplete evaporation in the evaporator.

[0333] In the previous paragraphs it has been explained how the refrigerant passes through the main circuit. In addition to this, in an embodiment of the invention, a further return section 40 can also be provided. As can be seen in Fig. 10a, this return section 40 can be connected to the main circuit via connections 42 and 44. In this case, connection 42 is provided downstream of the heat exchanger 48 and upstream of the expansion valve 18, in the embodiment shown upstream of the filter-drier 34. Connection 44 is provided between the first compressor 12 and the second compressor 14.

[0334] That is, the refrigerant is fed to the return section in the state it was in at process point 7, which is supercritical, high pressure and low temperature.

[0335] In the return section 40, the refrigerant passes through an expansion valve 46, which reduces the pressure of the refrigerant to an intermediate pressure. Downstream of the expansion valve 46 (process point 8), the refrigerant exists as a wet vapor and is at an intermediate pressure and low temperature.

[0336] Further downstream, in the return section 40, the refrigerant passes through a heat exchanger 48, which heats it. The heating is carried out so that the refrigerant is thereby evaporated, i.e. transferred to a gaseous state, or at least transferred to the dew point (i.e. the transition between wet steam and gas). It is also possible to heat up to just before the dew line. The mixing enthalpy from process point 3 and process point 9 can ideally be in the gaseous region. For this, the heat exchangers 32, 48 can be designed accordingly, and the opening of the further expansion valve 46 can be adjusted accordingly to adjust the ratio of the mass flow in the return section 40 to the mass flow in the main circuit. That is, since an energy input via the heat exchanger is necessary for the phase transition, downstream of the heat exchanger 48 (i.e. at process point 9) the refrigerant is again in gaseous state (or from wet steam to gas, but possibly as wet steam) and is present at medium pressure and low temperature. In particular, the refrigerant has a lower specific enthalpy at process point 9 than at process point 3, which causes a mixture of this refrigerant (see process point 4) to have a reduced temperature compared to process point 3.

[0337] It should be noted that after the detailed description of the above embodiments, in which the cyclic process shown in each diagram "B" was described in detail, the following embodiments are described more concisely in the sense of simple description, but the above embodiments with respect to the corresponding diagrams and with respect to the corresponding processes apply equally to the embodiments described below, and those skilled in the art will understand them with the aid of the diagrams and in conjunction with the detailed above description.

[0338] According to the embodiment of the cooling system 10 shown in FIG. 4A and the corresponding Mollier diagram according to FIG. 4B, a medium pressure vessel 70 can be added or replaced at the first connection point. In this case, a high pressure control device 74, which can in particular be formed as an expansion valve, can be arranged in the main circuit upstream of the inlet 71 of the medium pressure vessel 70. The high pressure can be reduced to a medium pressure by the high pressure control device 74. In particular, in this case, a transition from a liquid or supercritical phase to a wet vapor phase can be carried out. A liquid refrigerant can be sent to the expansion device 18 via a first outlet 72 of the medium pressure vessel 70 and / or a refrigerant at least partially in a gaseous or wet vapor phase can be introduced into the return section 40 via a second outlet 73 of the medium pressure vessel 70. In this case, the refrigerant can be sucked out of the second compressor 14 via the return section 40. Instead of feeding the refrigerant at medium pressure between the compressors 12 and 14, a low pressure refrigerant can be mixed with the refrigerant in the gaseous phase. For example, the second connection point 44 may couple the return section 40 to the main circuit upstream of the first compressor 12 .

[0339] Use of the intermediate pressure vessel 70 may eliminate the second heat exchanger 50 and / or the separate cooling component 32. The expansion device 18 may be controlled based on the evaporator outlet temperature, for example, as sensed by a sensor in the piping section 202. The expansion device 18 may thereby control the superheat of the refrigerant.

[0340] The embodiment according to Figures 5A and 5B is based on the embodiment according to Figure 4A with the addition of a second cooling component 32. In this case, a first cooling of the refrigerant can be achieved between the compressors 12, 14 by the second cooling component 32. A further cooling of the refrigerant can then be achieved by mixing the refrigerant with cooled refrigerant from the return section at the connection point 44. The second cooling component 32 can be equipped with a ventilator, whereby the cooling capacity of the second cooling component 32 can be controllable via the ventilator speed.

[0341] In another embodiment of the cooling system 10 according to Figures 6A and 6B, the intermediate pressure vessel 70 can be connected to the main circuit downstream of the evaporator 11, advantageously downstream of the liquid separator 30, downstream of the first compressor 12 and / or downstream of the second cooling component 32 via a piping segment 216 connecting the second vessel outlet 73 with the further connection point 52. The first mixed refrigerant flow can flow from the further connection point 52 to the second connection point 44.

[0342] A junction 42 is arranged downstream of the process point 6, where the refrigerant flow splits. In the main circuit, downstream of the junction, a high pressure control device 74 (e.g. an expansion valve) is arranged, and also in the return section, an expansion device 46 is arranged. To simplify the state diagram of Fig. 6B, it is assumed that the devices 74, 46 expand the refrigerant in the same way, so that the process points arranged downstream of these devices are both labeled 8b in Fig. 6B, and the process point downstream of the device 46 in Fig. 6A is called 8b', but in Fig. 6B it corresponds to the process point 8b. However, those skilled in the art will understand that this is only an example, and that the devices 74 and 46 can be of different forms in other embodiments.

[0343] After the refrigerant is decompressed (process point 8b, FIG. 6A), the refrigerant flow may be split into two flows (process points 7 and 8a). The decompressed refrigerant flow at process point 8b′, which is subsequently heated via heat exchanger 48 to process point 8c, may be in wet vapor phase (process point 8c). In particular, the refrigerant is in a completely gaseous state or on the saturation line 804 at process point 8a. The state of the cooling medium may be adjusted by the temperature of the heated refrigerant between process points 5 and 6 and the mass flow ratio between process points 5 and 6 as well as between 8b and 8c. The heat flow to the return section 40 may be proportional to the thermal coupling area of ​​the heat exchanger 48. Process point 8c may be variable and may also coincide with process point 8a, for example.

[0344] Due to the second cooling component 32, the refrigerant can be partially liquid at another connection point. To prevent wet suction, i.e. contact of the second compressor 14 with a liquid phase, a corresponding temperature compensation can be realized via the return section 44, and a completely gaseous refrigerant is provided at the inlet of the second compressor 14.

[0345] In the cooling system, three pressure levels can be distinguished. Figure 7 separates a primary low pressure area from a secondary intermediate pressure area by line AA'. The low pressure area is defined by the outlet of the expansion device 18 and the compressor inlet of the first compressor 12. The tertiary high pressure area starts at the outlet of the second compressor 14 and extends to the respective pressure reducer in the form of the expansion device 18 and / or another expansion device 46. The return section may have an extended piping segment downstream of the secondary side of the heat exchanger 48.

[0346] The cooling system 10 can be used in a centrifuge 300 to cool a centrifuge bowl 301 (FIG. 8). In this case, the evaporator winding 302 of the evaporator 11 can be arranged with a relatively large surface contact on the outer wall of the centrifuge bowl in order to maximize the heat transfer from the rotor interior space to the evaporator winding 302. Advantageously, the windings of the evaporator winding 302 can be at least partially pressed or at least partially flattened pressed against the rotor tank 301. In this case, the flattened windings of the evaporator winding 302 can be arranged flush with each other on a straight part of the centrifuge bowl. When using CO2 as the refrigerant, the tube diameter of the evaporator winding 302 can be reduced, thereby increasing the surface contact between the evaporator winding 302 and the rotor tank 301.

[0347] According to one embodiment, the evaporator winding 302 may have a tube with an outer tube diameter of 16 mm and a wall thickness of 1 mm, each winding having a contact length of 11.6 mm in the x-direction, and the evaporator winding 302 has 10 contact windings in the vertical portion in the X-direction, resulting in a total length in the X-direction of 116 mm ( FIG. 9A ).

[0348] According to another embodiment, the evaporator winding 302 may have a tube with an outer tube diameter of 10 mm and a wall thickness of 1 mm, each winding having a contact length of 8.9 mm in the X direction, and the evaporator winding 302 has 14 contact windings in the vertical part in the X direction, resulting in a total length in the X direction of 124.6 mm (FIG. 9B).

[0349] As shown in Figures 9A and 9B, the increase in contact area is equivalent to a normalized cooling capacity of 2 kW, 40 W / (m 2 This results in a change in the temperature difference between the inner surface of the tube and the inner surface of the tank with the normalized U-value (K) and the evaporation temperature. The temperature of the inner surface of the tank approaches the evaporation temperature with the increase in area. With the above assumptions, the temperature difference with the outer surface of the tube is: 0.216m 2 :9.28K 0.23m 2 :8.7K

[0350] Correspondingly, the temperature at the edge of the tube can be reduced by 0.58 K due to the increased area, which allows the tank temperature to be reduced as well. Lower tank temperatures result in better cooling of the sample. Furthermore, the reduction in the tube diameter also saves material.

[0351] In this document, when relative terms such as "nearly," "substantially," or "about" are used, the terms should also include the exact terms, i.e., "substantially straight" should be interpreted as including "(exactly) straight."

[0352] It should be noted that in this document, where steps are mentioned, the order in which the steps are listed in this document may be random. That is, the order in which the steps are mentioned may be random unless otherwise stated or obvious to the skilled person. That is, in this document, for example, when a method is described as including steps (A) and (B), this does not necessarily mean that step (A) is performed before step (B), but it is also possible that step (A) is performed (at least partially) simultaneously with step (B), or that step (B) is performed before step (A). Furthermore, a step (X) preceding another step (Z) does not mean that there is no step between step (X) and step (Z). That is, a step (X) before a step (Z) includes the situation in which step (X) is performed immediately before step (Z), but also includes the situation in which one or more steps (Y1), ..., followed by (X) are performed before step (Z). The corresponding idea applies when terms such as "after" or "before" are used.

[0353] Although preferred embodiments have been described above with reference to the drawings, those skilled in the art will understand that these embodiments have been described for illustrative purposes only and should not be construed as limiting the scope of the present invention as defined by the claims.

Claims

1. A laboratory instrument (300) comprising a cooling system (10), The cooling system (10) comprises: an evaporator (11); a first compressor (12); a second compressor (14); a cooling component (16); an expansion device (18); a piping system (20', 21') connecting the evaporator (11), the first compressor (12), the second compressor (14), the refrigeration component (14), and the expansion device (18) to one another; and the cooling system (10) contains a refrigerant, the refrigerant being carbon dioxide; the first compressor (12) and the second compressor (14) are arranged in series with each other; the first compressor (12) is configured to compress the refrigerant from a primary pressure range to a secondary pressure range, the secondary pressure range having a higher pressure than the primary pressure range; the second compressor (14) is configured to compress the refrigerant from the secondary pressure range to a tertiary pressure range, the tertiary pressure range having a higher pressure than the secondary pressure range; the expansion device (18) is configured to regulate the pressure of the refrigerant to reduce the pressure of the refrigerant from the secondary pressure range to the primary pressure range; The expansion device (18) is controllable based on the pressure of the refrigerant downstream of the evaporator (11) and upstream of the first compressor (12).

2. The cooling system has a main circuit, the main circuit includes the evaporator (11), the first compressor (12), the second compressor (14), the refrigeration component (16), the expansion device (18), and at least a portion of the piping system (20′, 21′); The laboratory equipment (300) of claim 1, wherein the refrigerant is present in the main circuit.

3. the refrigeration system (10) comprises a high-pressure control device (74) configured to reduce the pressure of the refrigerant, in particular to reduce the pressure from the tertiary pressure range to the secondary pressure range or to reduce the pressure within the tertiary pressure range, The laboratory equipment (300) of claim 1, wherein the high pressure controller (74) is controlled based on the pressure of the refrigerant downstream of the cooling component (16) and upstream of the high pressure controller (74).

4. The refrigeration system (10) includes a circuit controller configured to control the flow of the refrigerant; 2. The laboratory equipment (300) of claim 1, wherein the circuit controller is configured to control the expansion device (18) in response to an outlet temperature of the cooling component and / or an ambient temperature to set a pressure within the tertiary pressure range.

5. The refrigeration system (10) includes a circuit controller configured to control the flow of the refrigerant; 10. The laboratory equipment (300) of claim 1, wherein the circuit controller is configured to control the opening of the expansion device (18) based on an evaporator outlet temperature.

6. The laboratory instrument (300) of claim 1, wherein the laboratory instrument is a centrifuge.

7. 2. The laboratory equipment of claim 1, wherein the cooling system is configured such that when the refrigerant leaves the first compressor at an outlet temperature, the refrigerant is delivered to the second compressor at an inlet temperature that is lower than the outlet temperature.

8. 3. The laboratory equipment of claim 2, wherein the cooling system includes an intermediate pressure vessel configured to separate the refrigerant into a liquid phase and a vapor phase, the intermediate pressure vessel being positioned upstream of the expansion device in the main circuit.

9. The intermediate pressure vessel (70) is formed as a three-way collector, and a vessel inlet (71) configured to direct a refrigerant into said medium pressure vessel (70) and positioned downstream of said refrigeration component (16); a first vessel outlet (72) configured to direct liquid refrigerant from said medium pressure vessel into a piping section (208) and located upstream of said evaporator (11) and / or upstream of said expansion device (18); a second vessel outlet (73) connecting said intermediate pressure vessel (70) to the return section (40) and adapted to direct gaseous refrigerant into said return section (40); The laboratory instrument (300) of claim 8, comprising:

10. 3. The laboratory equipment (300) of claim 2, wherein the cooling system (10) has a return section (40) fluidly connected to the main circuit at a first connection point (42) and a second connection point (44).

11. 11. The laboratory equipment (300) of claim 10, wherein the second connection point (44) is located in the main circuit downstream of the first compressor (12) and upstream of the second compressor (14).

12. The refrigeration system (10) comprises a heat exchanger (48), the heat exchanger (48) having a primary side disposed downstream of the refrigeration component (16) in the main circuit, the heat exchanger (48) configured to cool the refrigerant in the main circuit; the heat exchanger (48) is configured to bring the refrigerant to a predetermined temperature at the first connection point (42) and / or the piping section (208) that is less than an outlet temperature of the refrigeration component (16); The heat exchanger (48) has a secondary side disposed in the return section (40), and the heat exchanger (48) is configured to absorb heat from the refrigerant through the primary side to heat the refrigerant in the return section (40), and to release the absorbed heat to the refrigerant through the secondary side. The laboratory instrument (300) of claim 10.

13. 2. The laboratory equipment (300) of claim 1, wherein the refrigeration system (10) includes a filter dryer (34) configured to remove moisture from the refrigerant, the filter dryer (34) being located in the main circuit downstream of the refrigeration component (16) and / or upstream of the expansion device (18).

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