KÜHLKREISLAUF

Description

Technical area

[0001] The present invention relates to a cooling circuit and a method for operating a cooling circuit. Technical background

[0002] It is known from the prior art to use a refrigeration machine based on the compression refrigeration principle for cooling. The basic components of such a refrigeration machine are a compressor, a heat exchanger, such as a condenser (air- or water-cooled), a throttling device (usually an expansion valve), and an evaporator. The compressor draws the gaseous working medium, i.e. the refrigerant, from the evaporator. The refrigerant is brought to a higher pressure in the compressor. This heats up the gas. This compressed gas then enters the heat exchanger or condenser, where it is cooled under almost constant pressure. Due to the heat removal, the refrigerant liquefies or cools down. The refrigerant then reaches the throttling device, where it is expanded to a lower pressure. With the addition of heat in the downstream evaporator, the refrigerant begins to boil, i.e., evaporate.The surroundings cool down. This process continues continuously as long as the compressor is running. The refrigerant is never consumed because it is in a closed circuit.

[0003] Refrigerant compressors, as components in a refrigeration cycle, are often described with the theoretically underlying isentropic change of state. This is because refrigerant compressors are often not actively cooled, and dissipation occurs due to internal friction. In addition, in suction-gas-cooled machines, the motor and possibly also the power electronics are cooled by the refrigerant before it enters the working chamber. This means that the overall consideration must be based on superisentropic compression, with a final compression temperature significantly above the ambient temperature. From a thermodynamic perspective, however, this only makes limited sense. With regard to the optimal thermodynamic cycle according to Carnot, the conclusion is that the aim should be to achieve the most isentropic compression possible below ambient temperature, and above ambient temperature the compression should ideally be isothermal.Furthermore, any heating of the suction gas before entering the working chamber should be avoided. Ideally, the entry occurs directly from the boiling point, although this is technically difficult to achieve.

[0004] Especially with refrigerants with a comparatively low molecular weight, (hyper)isentropic compression at corresponding pressure ratios results in a very high final compression temperature, especially when an internal heat exchanger is also used. This can cause long-term damage to the compressor or severely limit its operating limits.

[0005] Technically, to avoid very high final compression temperatures, either the cylinder head is cooled with a simple fan or vapor injection (liquid and / or gaseous) is used. The latter, in particular, is sometimes used in combination with the economizer circuit. This offers several options for injecting the refrigerant. The refrigerant can be injected or blown into the suction side, or it can be injected or blown directly into the working chamber via ducts at a pressure level between the discharge and suction gases. Water cooling is sometimes also used in process gas compressors or very large industrial refrigerant compressors, as well as in NH3 reciprocating compressors.

[0006] WO 2014 / 100156 A1 discloses a compressor assembly that may include a compression cylinder and a compression piston disposed within the compression cylinder, which compresses vapor disposed within the compression cylinder from a suction pressure to a discharge pressure. The compressor assembly may additionally include a crankshaft that cyclically moves the compression piston within the compression cylinder, and an injection port in fluid communication with the compression cylinder that selectively supplies intermediate-pressure vapor at a pressure between the suction-pressure vapor and the discharge-pressure vapor to the compression cylinder. The injection port may transfer the intermediate-pressure vapor to the compression cylinder when the compression piston exposes the injection port and may be prevented from transferring the intermediate-pressure vapor to the compression cylinder when the compression piston blocks the injection port.

[0007] WO 2015 / 071128 A1 discloses a cooling circuit comprising a refrigerant compressor with a suction port and a pressure chamber having a pressure port, a condenser arranged downstream of the pressure port in the cooling circuit, having a fluid collection chamber in which a refrigerant reservoir is formed, an evaporator located in the cooling circuit between the condenser and the suction port, and a supply unit connected to the refrigerant reservoir on the one hand and to the pressure chamber on the other, for supplying refrigerant from the refrigerant reservoir to the pressure chamber, which supply unit comprises a pump unit for the refrigerant. The pump unit has a pressure-tight housing provided with only an inlet and an outlet as access points, in the pump chamber of which a pump element movable for pumping the refrigerant is arranged.

[0008] US 2015 / 159919 A1 discloses a heat pump unit forming a heat pump cycle in which a reciprocating compressor, a condenser, an expansion valve, and an evaporator are arranged in a refrigerant circuit path. The heat pump unit includes a refrigerant liquid return path for returning a portion of the refrigerant liquid condensed by the condenser to an outlet chamber provided in a cylinder head assembly of the reciprocating compressor, so that a portion of the refrigerant liquid is supplied to the outlet chamber via the refrigerant liquid return path, and an outlet gas passage is cooled by the latent heat of vaporization of the refrigerant liquid. Accordingly, US 2015 / 159919 A1 describes the supply of refrigerant liquid to a pressure chamber of the compressor. US 2015 / 1599919 A1 discloses a refrigeration cycle according to the preamble of claim 1.

[0009] Despite the numerous advantages of state-of-the-art cooling circuits, they still have potential for improvement. For example, cooling using air flow at the cylinder head is a very simple method that can be used to slightly reduce the final compression temperature. However, efficiency advantages or options for influencing part-load operation are not possible. The supply of refrigerant in conjunction with economizer circuits has the fundamental disadvantage that the pressure level is sometimes considerably below the high-pressure level. While these circuits are capable of increasing efficiency and deliberately broadening the part-load range, their range of application is always determined by the pressure level and condition of the injected refrigerant. Furthermore, the injection takes place either in gaseous form or in a more or less well-defined vapor with a corresponding liquid content.Potentially used water cooling circuits for compressors are expensive and require all the components for the water circuit, including its cooling. Furthermore, water as a coolant is not readily available everywhere. Object of the invention

[0010] It would therefore be desirable to provide a cooling circuit and a method for operating a cooling circuit that at least largely avoid the disadvantages of known cooling circuits. In particular, the invention is intended to enable heat dissipation during compression, the targeted lowering of the final compression temperature, and the adjustment of the volumetric efficiency (partial load case) in a particularly efficient manner. General description of the invention

[0011] This problem is addressed by a cooling circuit and a method for operating a cooling circuit having the features of the independent patent claims. Advantageous further developments, which can be implemented individually or in any combination, are presented in the dependent claims.

[0012] In the following, the terms "have," "have," "comprise," or "include," or any grammatical variations thereof, are used non-exclusively. Accordingly, these terms can refer both to situations in which, besides the features introduced by these terms, no further features are present, or to situations in which one or more further features are present. For example, the expression "A has B," "A has B," "A comprises B," or "A includes B" can refer both to the situation in which, apart from B, no further element is present in A (i.e., a situation in which A consists exclusively of B), and to the situation in which, in addition to B, one or more further elements are present in A, for example, element C, elements C and D, or even further elements.

[0013] Furthermore, it should be noted that the terms "at least one" and "one or more," as well as grammatical variations of these terms, when used in connection with one or more elements or features and intended to express that the element or feature may be provided singly or multiple times, are generally used only once, for example, when the feature or element is first introduced. Upon subsequent re-mention of the feature or element, the corresponding term "at least one" or "one or more" is generally no longer used, without limiting the possibility that the feature or element may be provided singly or multiple times.

[0014] Furthermore, the terms "preferably," "in particular," "for example," or similar terms are used below in connection with optional features, without limiting alternative embodiments. Thus, features introduced by these terms are optional features, and these features are not intended to limit the scope of the claims, and in particular the independent claims. Thus, as those skilled in the art will recognize, the invention can also be carried out using other embodiments. Similarly, features introduced by "in one embodiment of the invention" or "in an embodiment of the invention" are understood as optional features, without limiting alternative embodiments or the scope of the independent claims.Furthermore, these introductory expressions are intended to leave untouched all possibilities of combining the features introduced thereby with other features, whether optional or non-optional.

[0015] In a first aspect of the present invention, a refrigeration cycle is therefore proposed. The term "refrigeration cycle," as used herein, is a broad term to which its usual and common meaning should be attributed, as understood by those skilled in the art. The term is not limited to a specific or adapted meaning. The term can refer, without limitation, in particular to a system, preferably a closed system, that uses a compressor to transport thermal energy from a colder location to be cooled to a warmer environment. The refrigeration cycle can be based on a thermodynamic cycle.

[0016] The cooling circuit comprises a refrigerant compressor with at least one working chamber. If the refrigerant compressor is designed as a multi-cylinder machine, for example, the refrigerant compressor has more than one working chamber, for example, one working chamber per cylinder.

[0017] The term "refrigerator compressor," as used herein, is a broad term to which its ordinary and customary meaning should be given, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. The term can refer, without limitation, specifically to a machine (fluid energy machine) that applies mechanical work to an enclosed gas. Compressors are used to compress gases. They increase the pressure and density of the gas.

[0018] The term "working chamber," as used herein, is a broad term to which its ordinary and customary meaning should be given, as understood by one skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, refer in particular to a chamber of a compressor in which the compression of the gas takes place. The working chamber is located between the compressor housing and one or more displacers, such as pistons. From the perspective of the flow of the working medium in a compressor, the working chamber is located between a suction chamber, into which the gas is initially drawn, and a pressure chamber, to which the compressed gas is fed before being expelled from the compressor.For example, in a reciprocating piston compressor, gas in a cylinder is sucked into the suction chamber by a reciprocating piston, compressed in the working chamber, and the compressed gas is expelled from the pressure chamber.

[0019] The cooling circuit further comprises a heat exchanger with a fluid collection chamber. The fluid collection chamber is designed to form a refrigerant reservoir. The term "heat exchanger," as used herein, is a broad term to which its usual and common meaning should be attributed, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, refer in particular to a device that transfers thermal energy from one material stream to another.

[0020] The heat exchanger can be a condenser or gas cooler. The term "condenser," as used herein, is a broad term to which its ordinary and common meaning should be given, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, refer in particular to an apparatus in which a substance is converted from the gaseous state to the liquid state by condensation. The term "condenser" is used synonymously with the term "condenser." In refrigeration systems, condensers serve to liquefy the vaporous refrigerant. This enables a closed cycle in refrigeration systems. The term "gas cooler," as used herein, is a broad term to which its ordinary and common meaning should be given, as understood by those skilled in the art.The term is not limited to a specific or adapted meaning. The term can, without limitation, refer in particular to a device that extracts heat from a gas and thus cools it. For example, in supercritical operation, the refrigerant is not liquefied.

[0021] Within the scope of the present invention, the refrigerant is liquefied in the heat exchanger during subcritical operation, as is the case with the usual commercially used refrigerants (except carbon dioxide - CO 2 ), but during supercritical operation the refrigerant is only cooled without being liquefied.

[0022] The term "fluid collection chamber," as used herein, is a broad term to be given its ordinary and customary meaning as understood by one skilled in the art. The term is not limited to any specific or adapted meaning. The term may, without limitation, refer specifically to a chamber in which refrigerant is temporarily collected and stored. Thus, during subcritical operation, the fluid collection chamber collects liquid refrigerant, but during supercritical operation, cooled, gaseous refrigerant. The fluid collection chamber may be a liquid separator. The purpose of a liquid separator is to continuously supply liquid refrigerant to the expansion device and to store excess refrigerant in the circuit.

[0023] The cooling circuit further comprises a supply unit. The supply unit is connected to the fluid collection chamber and the refrigerant compressor. The supply unit has a high-pressure pump and an injector. The supply unit is designed to supply refrigerant from the refrigerant reservoir to the working chamber via the injector at a pressure above a discharge pressure of the refrigerant compressor.

[0024] The term "supply unit," as used herein, is a broad term to which its ordinary and customary meaning should be given, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. The term may, without limitation, refer in particular to a device configured to withdraw refrigerant from the fluid collection chamber and convey it by means of a high-pressure pump to the compressor, where the refrigerant is injected directly into the working chamber by means of the injector.

[0025] The term "high-pressure pump," as used herein, is a broad term to which its ordinary and common meaning should be given, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, refer in particular to a pump that generates high pressure; the generated pressure is in any case above the discharge pressure of the refrigerant compressor. The operating principle of the pump encompasses both mechanically and thermally driven pressure increase.

[0026] The term "injector," as used herein, is a broad term to which its usual and common meaning should be given, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. The term may, without limitation, refer in particular to a device designed to supply or inject refrigerant into the working chamber of the refrigerant compressor. The injector may include a valve. For example, the injector comprises one or more injection nozzles, each consisting of a nozzle body and a nozzle needle.

[0027] Accordingly, in the cooling circuit according to the invention, the cooling of the compression takes place in a refrigerant compressor with a targeted supply of cooling refrigerant from ambient temperature into the working chamber. The refrigerant is supplied at a pressure significantly above the high pressure in the refrigeration circuit. The necessary high pressure is provided by a pump for liquid or supercritical refrigerant. Injection is ensured by one or more injection nozzles into the working chamber. First, refrigerant in the liquid or supercritical state is taken from a reservoir on the high pressure side after the heat exchanger in the form of a condenser / gas cooler and compressed by a high pressure pump to a pressure level significantly above the high pressure. This pressure level must be selected such that no evaporation occurs due to pressure losses within the downstream lines and components.On the other hand, a sufficient pressure level must be achieved to provide sufficient pre-pressure to the injector. This operating mode increases efficiency.

[0028] As a useful side effect of the freely selectable injection point, the mass present in the working chamber can be adjusted to increase the re-expansion time by selectively injecting high-pressure refrigerant during the expansion phase (piston downward movement). This makes it possible to ensure that only a corresponding, limited amount of fresh suction gas is taken in during the next intake.

[0029] The supply unit can be configured to supply refrigerant from the refrigerant reservoir to the working chamber via the injector at a pressure that is at least 4 bar and preferably at least 5 bar above the discharge pressure of the refrigerant compressor. The pressure can, for example, be up to 200 bar above the discharge pressure of the refrigerant compressor. This pressure level ensures that no evaporation of the refrigerant occurs due to pressure losses within the downstream lines and components. Furthermore, this represents a sufficient pressure level to apply sufficient pre-pressure to the injector.

[0030] The supply unit can be configured to supply essentially single-phase refrigerant from the refrigerant reservoir to the working chamber via the injector. This enables very efficient cooling of the compression process.

[0031] The supply unit can be configured to supply refrigerant from the refrigerant reservoir to the working chamber via the injector in a liquid or supercritical state. Thus, the cooling circuit is suitable for operation in both the subcritical and supercritical refrigerant ranges.

[0032] The injector can have at least one injection nozzle. In particular, several injection nozzles can be provided per working chamber or per compressor if multiple working chambers are present. This allows the refrigerant to be atomized in the working chamber, increasing the cooling effect through rapid evaporation.

[0033] The injector can be configured to distribute the refrigerant within the working chamber and / or to spray the refrigerant onto a refrigerant compressor wall of the refrigerant compressor that defines the working chamber, in particular a cylinder wall. Accordingly, the injection process can preferably be carried out in such a way that the finely atomized refrigerant jet is evenly distributed within the working chamber and / or sprayed in portions onto the cylinder wall.

[0034] The injector can have a valve. The refrigerant compressor can have at least one valve plate. The valve can be integrated into the valve plate or adjacent to the valve plate. In other words, the injector can be installed directly in the valve plate or connected to the working chamber by a thin connecting line. An arrangement as close as possible to the working chamber is preferred. The injector is designed such that the channel from the valve, preferably an electronically controlled valve (e.g. piezo-controlled), is sufficiently short to utilize the effect of boiling delay due to the expansion on the pressure level in the working chamber. The boiling delay during expansion via the injector should lead to targeted evaporation as a spray in the working chamber of the compressor.

[0035] The term "valve plate," as used herein, is a broad term to which its ordinary and common meaning should be given, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. The term can refer, without limitation, in particular to a plate-shaped component that closes the working chamber of a compressor and in which valves are arranged for admitting a fluid medium into and discharging the fluid medium from the working chamber. In a reciprocating piston compressor, the valve plate is usually arranged on the side of the compressor housing facing the top dead center of the piston.

[0036] The cooling circuit can further comprise a control unit configured to time-control the supply of the refrigerant to the working chamber by means of the injector. Accordingly, the injector can inject the refrigerant into the working chamber at a time triggered by the control unit.

[0037] The term "control unit," as used herein, is a broad term to which its ordinary and customary meaning should be given, as understood by those skilled in the art. The term is not limited to any specific or adapted meaning. The term can refer, without limitation, in particular to a central component of a computer in which computational operations are performed and which controls other functions.

[0038] The control unit can be configured to control the supply of refrigerant to the working chamber by means of the injector based on at least one parameter selected from the group consisting of: pressure in the working chamber, temperature in the working chamber, crank angle position of the refrigerant compressor, suction temperature of the refrigerant compressor, suction pressure of the refrigerant compressor, high temperature in the cooling circuit, and high pressure in the cooling circuit. These possible signals can thus be used to specifically adjust the injection sequence.

[0039] The timing control can include a time and / or a length of time the refrigerant is supplied to the working chamber via the injector. Accordingly, the time and / or length of injection of the refrigerant into the working chamber and / or the length of injection, and thus the quantity, can be specifically controlled.

[0040] The control unit can be configured to control the supply of refrigerant to the working chamber by means of the injector as a continuous injection quantity of refrigerant that increases toward a top dead center. Accordingly, the injected quantity of refrigerant is not necessarily constant, but may increase toward the end of compression in order to keep the additional proportion of refrigerant mass introduced into the compressor as low as possible.

[0041] The control unit can be configured to control the supply of refrigerant to the working chamber by means of the injector during an expansion process of the refrigerant compressor, during a compression process of the refrigerant compressor, and / or at multiple times during all working cycles of the refrigerant compressor. Thus, the time can occur both during the compression phase (upward movement of the piston) and during the expansion phase (downward movement of the piston). Likewise, the injection can occur in multiple sequences that extend over the entire working cycle.

[0042] The cooling circuit can further include an optional aftercooler for cooling the refrigerant from the refrigerant reservoir. The aftercooler increases the cooling capacity when cooling the compressor, as additional heat is extracted from the high-pressure refrigerant. The aftercooler can, for example, be designed to cool the refrigerant from the refrigerant reservoir to a temperature that is essentially identical to the ambient temperature of the cooling circuit. The aftercooler can be arranged between the high-pressure pump and the injector.

[0043] The refrigerant compressor may have a refrigerant compressor housing, with the high-pressure pump being integrated into the refrigerant compressor housing. This allows for a compact arrangement of the high-pressure pump and compressor.

[0044] The refrigerant compressor can be a reciprocating piston compressor with at least one valve plate and at least one piston. The injector can be integrated into the valve plate or arranged adjacent to the valve plate on the refrigerant compressor. This allows the reciprocating piston to utilize the full stroke in the cylinder.

[0045] In a further aspect of the present invention, a method for operating a refrigeration circuit is proposed. The refrigeration circuit comprises a refrigerant compressor with at least one working chamber, a heat exchanger with a fluid collection chamber, wherein the fluid collection chamber is designed to form a refrigerant reservoir, and a supply unit. The supply unit is connected to the fluid collection chamber and the refrigerant compressor. The supply unit comprises a high-pressure pump and an injector. The method comprises the following steps, preferably in the specified order: Sucking in a refrigerant by means of the refrigerant compressor, compressing the refrigerant by means of the refrigerant compressor, cooling the refrigerant by means of the heat exchanger, supplying the cooled refrigerant to the fluid collection space, and supplying refrigerant from the refrigerant supply of the fluid collection space to the working space by means of the injector at a pressure above a discharge pressure of the refrigerant compressor.

[0046] Accordingly, in the method according to the invention, the cooling of the compression takes place in a refrigerant compressor with a targeted supply of cooling refrigerant from ambient temperature into the working chamber. The refrigerant is supplied at a pressure significantly above the high pressure in the refrigeration circuit. The necessary high pressure is provided by a pump for liquid or supercritical refrigerant. Injection is ensured by one or more injection nozzles into the working chamber. First, refrigerant in the liquid or supercritical state is taken from a reservoir on the high pressure side after the heat exchanger in the form of a condenser / gas cooler and compressed by a high pressure pump to a pressure level significantly above the high pressure. This pressure level must be selected such that no evaporation occurs due to pressure losses within the downstream lines and components.On the other hand, a sufficient pressure level must be achieved to provide sufficient pre-pressure to the injector. This operating mode increases efficiency.

[0047] As a useful side effect of the freely selectable injection point, the mass present in the working chamber can be adjusted to increase the re-expansion time by selectively injecting high-pressure refrigerant during the expansion phase (piston downward movement). This makes it possible to ensure that only a corresponding, limited amount of fresh suction gas is taken in during the next intake.

[0048] The term "cooling," as used here, is a broad term to which its ordinary and common meaning should be given, as understood by one skilled in the art. The term is not limited to any specific or adapted meaning. The term can, without limitation, refer in particular to a process by which heat or thermal energy is removed from a system or object. Cooling is therefore also referred to as desuperheating. The removal of heat from solids and liquids occurs through heat transfer along a temperature gradient. The processes involved are heat conduction, heat radiation, and convection. Cooling is usually based on the transfer of heat from the body to be cooled to the cooling medium and its transport.

[0049] The refrigerant can be supplied from the refrigerant reservoir to the working chamber via the injector at a pressure that is at least 4 bar and preferably at least 5 bar above the discharge pressure of the refrigerant compressor. For example, the pressure can be up to 200 bar above the discharge pressure of the refrigerant compressor. This pressure level ensures that no evaporation of the refrigerant occurs due to pressure losses within the downstream lines and components. Furthermore, this pressure level provides sufficient pre-pressure to apply sufficient pre-pressure to the injector.

[0050] Cooling the refrigerant using the heat exchanger can involve recooling and / or condensing the refrigerant. This increases the cooling capacity when cooling the refrigerant compressor.

[0051] The refrigerant can be supplied from the refrigerant reservoir to the working chamber by means of the injector in a substantially single-phase state.

[0052] The refrigerant can be supplied from the refrigerant reservoir to the working chamber via the injector in a liquid or supercritical state. This makes the cooling circuit suitable for operation in both the subcritical and supercritical refrigerant range.

[0053] The method may further comprise distributing the refrigerant within the working chamber and / or spraying the refrigerant onto a refrigerant compressor wall of the refrigerant compressor that defines the working chamber by means of the injector. Accordingly, the injection process may preferably be carried out such that the finely atomized refrigerant jet is well distributed within the working chamber and / or sprayed in portions onto the cylinder wall.

[0054] The method may further comprise, by means of a control unit, timing the supply of the refrigerant to the working chamber by means of the injector. Accordingly, the injector can inject the refrigerant into the working chamber at a time triggered by the control unit.

[0055] The method may further comprise controlling the supply of refrigerant to the working chamber by means of the injector based on at least one parameter selected from the group consisting of: pressure in the working chamber, temperature in the working chamber, crank angle position of the refrigerant compressor, suction temperature of the refrigerant compressor, suction pressure of the refrigerant compressor, high temperature in the cooling circuit, and high pressure in the cooling circuit. These possible signals can thus be used to specifically adjust the injection sequence.

[0056] The timing control can include a time and / or a length of time the refrigerant is supplied to the working chamber via the injector. Accordingly, the time and / or length of injection of the refrigerant into the working chamber and / or the length of injection, and thus the quantity, can be specifically controlled.

[0057] The refrigerant can be supplied to the working chamber via the injector as a continuous injection quantity of refrigerant that increases toward top dead center. Accordingly, the injected quantity of refrigerant is not necessarily constant, but can increase toward the end of compression to enhance compressor cooling.

[0058] The method may further comprise controlling the supply of refrigerant to the working chamber by means of the injector during an expansion process of the refrigerant compressor, during a compression process of the refrigerant compressor, and / or at multiple points in time during a working cycle of the refrigerant compressor. Thus, the time can occur both during the compression phase (upward movement of the piston) and during the expansion phase (downward movement of the piston). Likewise, the injection can occur in multiple sequences that extend over the entire working cycle.

[0059] The method may further comprise cooling the refrigerant from the refrigerant reservoir using an aftercooler. The aftercooler increases the cooling capacity when cooling the compressor by removing additional heat from the high-pressure refrigerant.

[0060] The refrigerant can be cooled from the refrigerant reservoir to a temperature that is essentially identical to the ambient temperature of the cooling circuit using the aftercooler. The aftercooler can be located between the high-pressure pump and the injector.

[0061] The refrigerant compressor can be a reciprocating piston compressor with at least one valve plate and at least one piston. The injector can be integrated into the valve plate or arranged adjacent to the valve plate on the refrigerant compressor. This allows the reciprocating piston to utilize the full stroke in the cylinder.

[0062] Furthermore, within the scope of the present invention, a computer program is proposed which, when run on a computer or computer network, executes the method according to the invention in one of its embodiments.

[0063] Furthermore, within the scope of the present invention, a computer program with program code means is proposed for implementing the method according to the invention in one of its embodiments when the program is executed on a computer or computer network. In particular, the program code means can be stored on a computer-readable data carrier and / or a computer-readable storage medium.

[0064] The terms "computer-readable medium" and "computer-readable storage medium," as used herein, may refer in particular to non-transitory data storage devices, such as a hardware data storage medium on which computer-executable instructions are stored. The computer-readable medium or the computer-readable storage medium may, in particular, be or include a storage medium such as a random-access memory (RAM) and / or a read-only memory (ROM).

[0065] Furthermore, within the scope of the present invention, a data carrier is proposed on which a data structure is stored which, after being loaded into a working and / or main memory of a computer or computer network, can execute the method according to the invention in one of its embodiments.

[0066] Also proposed within the scope of the present invention is a computer program product with program code means stored on a machine-readable carrier in order to carry out the method according to the invention in one of its embodiments when the program is executed on a computer or computer network.

[0067] A computer program product is understood as a tradable product. It can, in principle, exist in any form, for example, on paper or a computer-readable data carrier, and can, in particular, be distributed via a data transmission network.

[0068] Finally, within the scope of the present invention, a modulated data signal is proposed which contains instructions executable by a computer system or computer network for carrying out a method according to one of the described embodiments.

[0069] With regard to the computer-implemented aspects of the invention, one, several, or even all method steps of the method according to one or more of the embodiments proposed here can be performed by means of a computer or computer network. Thus, in general, any of the method steps, including the provision and / or manipulation of data, can be performed by means of a computer or computer network. In general, these steps can comprise any of the method steps, excluding the steps that require manual work, for example, the provision of samples and / or certain aspects of performing actual measurements. Short description of the characters

[0070] Further details and features will become apparent from the following description of exemplary embodiments, particularly in conjunction with the subclaims. The respective features can be implemented individually or in combination with one another. The invention is not limited to the exemplary embodiments. The exemplary embodiments are illustrated schematically in the figures. Identical reference numerals in the individual figures designate identical or functionally identical elements, or elements that correspond to one another in terms of their functions.

[0071] In detail: Figure 1 shows a schematic circuit diagram of a cooling circuit according to the invention; and Figure 2 shows a schematic arrangement of the injector on the refrigerant compressor. Description of the embodiments

[0072] Figure 1shows a schematic circuit diagram of a cooling circuit 100 according to the invention. The cooling circuit 100 comprises a refrigerant compressor 102 with at least one working chamber 104. The cooling circuit 100 further comprises a heat exchanger 106. The heat exchanger 106 is connected to a pressure chamber, not shown in detail, of the refrigerant compressor 102, which pressure chamber has a pressure connection. Depending on the refrigerant used, the heat exchanger 106 is a condenser or gas cooler. For example, in the case of NH 3 as the refrigerant, the heat exchanger 106 is designed as a condenser and in the case of CO 2 as the refrigerant, the heat exchanger 106 is designed as a gas cooler. The heat exchanger 106 has a fluid collection chamber 108. The fluid collection chamber 108 is designed to form a refrigerant supply from refrigerant. Depending on the refrigerant used, the fluid collection chamber 108 is a collector or liquid separator.In order to realize a closed cooling circuit 100, the cooling circuit 100 further comprises an expansion element 110 connected to the heat exchanger 106 or the fluid collection chamber 108 and an evaporator 112 which is connected to the expansion element 110 and to a suction chamber of the refrigerant compressor 102, not shown in detail and having a suction connection.

[0073] The cooling circuit 100 further comprises a supply unit 114. The supply unit 114 is connected to the fluid collection chamber 108 and the refrigerant compressor 102. The supply unit 114 has a high-pressure pump 116 and an injector 118. The supply unit 114 is designed to supply refrigerant from the refrigerant supply of the fluid collection chamber 108 to the working chamber 104 by means of the injector 118 at a pressure above a discharge pressure of the refrigerant compressor 102. In particular, the supply unit 114 is designed to supply refrigerant from the refrigerant supply to the working chamber 102 by means of the injector 118 at a pressure that is at least 4 bar and preferably at least 5 bar above the discharge pressure of the refrigerant compressor 102. The pressure of the refrigerant supplied to the working chamber 102 can be up to 200 bar above the discharge pressure of the refrigerant compressor 102.The supply unit 114 is designed to supply essentially single-phase refrigerant from the refrigerant reservoir to the working chamber 104 by means of the injector 118. Thus, the supply unit 114 is further designed to supply refrigerant from the refrigerant reservoir to the working chamber 104 by means of the injector 118 in a liquid or supercritical state of the refrigerant.

[0074] The cooling circuit 100 further comprises a control unit 120. The control unit 120 is configured to temporally control the supply of refrigerant to the working chamber 104 by means of the injector 118. The temporal control comprises a time and / or a length of the supply of refrigerant to the working chamber 104 by means of the injector 118. Thus, the control unit 120 is configured to control the supply of refrigerant to the working chamber 104 by means of the injector 118 based on at least one parameter selected from the group consisting of: pressure in the working chamber 104, temperature in the working chamber 104, crank angle position of the refrigerant compressor 102, suction temperature of the refrigerant compressor 102, suction pressure of the refrigerant compressor 102, high temperature in the cooling circuit 100, and high pressure in the cooling circuit 100.In particular, the control unit 120 is configured to control the supply of refrigerant to the working chamber 104 by means of the injector 118 as a continuous injection quantity of refrigerant that increases toward a top dead center. In principle, the control unit 120 is configured to control the supply of refrigerant to the working chamber 104 by means of the injector 118 during an expansion process of the refrigerant compressor 102, during a compression process of the refrigerant compressor 102, and / or at multiple points in time during all working cycles of the refrigerant compressor 102.

[0075] The cooling circuit 100 further comprises an optional aftercooler 122 for cooling the refrigerant from the refrigerant reservoir. The aftercooler 122 is designed to cool the refrigerant from the refrigerant reservoir to a temperature that is substantially identical to an ambient temperature of the cooling circuit 100. As shown in Figure 1As shown, the aftercooler 122 is arranged between the high-pressure pump 116 and the injector 118. In contrast to the Figure 1 In the embodiment shown, the refrigerant compressor 102 may have a refrigerant compressor housing (not shown in detail) in which the high-pressure pump 116 is integrated.

[0076] Figure 2 shows a schematic arrangement of the injector 118 on the refrigerant compressor 102. In the left part of the Figure 2 the refrigerant compressor 102 is shown during a compression process and is in the right part of the Figure 2 the refrigerant compressor 102 during an expansion process. As shown in Figure 2 As shown, the refrigerant compressor 102 may be a reciprocating compressor having at least one valve plate 124 and at least one piston 126. The injector 118 may be integrated into the valve plate 124 or disposed adjacent to the valve plate 124 on the refrigerant compressor 102. As shown in Figure 2Further shown, the injector 118 may have at least one injection nozzle 128. The injector 118 may have a valve 130 that is integrated into the valve plate 124 or adjacent to the valve plate 124. The valve 130 is an electronically controlled valve, such as a piezo-controlled valve. The valve 130 can be controlled by the control unit 120. The injector 118 is designed to distribute the refrigerant within the working chamber 104 and / or to spray the refrigerant onto a refrigerant compressor wall 132 of the refrigerant compressor 102, such as a cylinder wall, that delimits the working chamber 104.

[0077] The following is based on the Figures 1 and 2A method for operating the cooling circuit 100 is described. The refrigerant coming from the evaporator 112 is sucked in by the refrigerant compressor 102. The sucked-in refrigerant is compressed by the refrigerant compressor 102. In the process, the pressure of the refrigerant increases. The compressed refrigerant is then discharged from the refrigerant compressor 102 and fed to the heat exchanger 106, where it is cooled by the heat exchanger 106. The refrigerant can be recooled in supercritical operation and liquefied in subcritical operation. In either case, heat is extracted from the refrigerant. The cooled refrigerant is then fed to the fluid collection chamber 108. There, it forms a refrigerant reservoir. A portion of the refrigerant from the refrigerant reservoir is then fed to the expansion element 110, where the refrigerant expands.This part of the refrigerant is then fed to the evaporator 112, where it evaporates and is then sucked in again by the refrigerant compressor 102.

[0078] The injector 118 is integrated into the valve plate 124 or arranged adjacent to the valve plate 124 on the refrigerant compressor 102. Another portion of the refrigerant from the refrigerant reservoir of the fluid collection chamber 108 is supplied by the high-pressure pump 116 to the working chamber 104 by means of the injector 118 at a pressure above a discharge pressure of the refrigerant compressor 102. The refrigerant from the refrigerant reservoir is supplied by the injector 118 to the working chamber 104 at a pressure that is at least 4 bar and preferably at least 5 bar above the discharge pressure of the refrigerant compressor 102, such as at least 10 bar above the discharge pressure of the refrigerant compressor 102. For this purpose, the refrigerant from the refrigerant reservoir is pressurized by the high-pressure pump 116 and then injected into the working chamber 104 by the injector 118.In particular, the injector 118 supplies the refrigerant from the refrigerant reservoir to the working chamber 104 in a substantially single-phase state. Thus, the injector supplies the refrigerant from the refrigerant reservoir to the working chamber in a liquid or supercritical state.

[0079] Optionally, the refrigerant from the refrigerant reservoir can be cooled by means of the aftercooler 122. The refrigerant from the refrigerant reservoir can be cooled by means of the aftercooler 122 to a temperature that is substantially identical to an ambient temperature of the cooling circuit 100. For this purpose, the aftercooler 122 can be arranged between the high-pressure pump 116 and the injector 118.

[0080] As in Figure 2As can be seen, the refrigerant is distributed within the working chamber 104 by means of the injector 118. Alternatively or additionally, the refrigerant is sprayed onto a refrigerant compressor wall 132 of the refrigerant compressor 102, which wall borders the working chamber 104, by means of the injector 118. The injector 118 is designed such that the channel from the electronically controlled valve 130 is sufficiently short to utilize the effect of the boiling delay due to the relaxation on the pressure level in the working chamber 104. The boiling delay during expansion via the injector 118 is intended to lead to targeted evaporation as a spray in the working chamber 104 of the refrigerant compressor 102.

[0081] The control unit 120 will time-control the supply of refrigerant to the working chamber 104 by means of the injector 118. The time-control of the supply of refrigerant to the working chamber 104 includes a time and / or a length of the supply of refrigerant to the working chamber 104 by means of the injector 118. The control of the supply of refrigerant to the working chamber 104 by means of the injector 118 is based on at least one parameter selected from the group consisting of: pressure in the working chamber 104, temperature in the working chamber 104, crank angle position of the refrigerant compressor 102, suction temperature of the refrigerant compressor 102, suction pressure of the refrigerant compressor 102, high temperature in the cooling circuit 100, and high pressure in the cooling circuit 100.In principle, the control of the supply of refrigerant to the working chamber 104 by means of the injector 118 can occur during an expansion process of the refrigerant compressor 102, during a compression process of the refrigerant compressor 102, and / or at multiple points in time during a working cycle of the refrigerant compressor 102. For example, the refrigerant is supplied to the working chamber 104 by means of the injector 118 as a continuous injection quantity of refrigerant that increases toward a top dead center. List of reference symbols

[0082] 100 Cooling circuit 102 Refrigerant compressor 104 Working chamber 106 Heat exchanger 108 Fluid collection chamber 110 Expansion element 112 Evaporator 114 Supply unit 116 High-pressure pump 118 Injector 120 Control unit 122 Aftercooler 124 Valve plate 126 Piston 128 Injector nozzle 130 Valve 132 Refrigerant compressor wall

Claims

1. Cooling circuit (100) comprising a refrigerant compressor (102) with at least one working chamber (104), a heat exchanger (106) with a fluid-collecting chamber (108), wherein the fluid-collecting chamber (108) is configured for forming a refrigerant reservoir of refrigerant, and a feed unit (114), wherein the feed unit (114) is connected to the fluid-collecting chamber (108) and the refrigerant compressor (102), wherein the feed unit (114) has a high-pressure pump (116) and an injector (118), characterized in that the feed unit (114) is configured for feeding refrigerant from the refrigerant reservoir to the working chamber (104) by means of the injector (118) at a pressure above a discharge pressure of the refrigerant compressor (102) .

2. Cooling circuit (100) according to the preceding claim, wherein the feed unit (114) is configured for feeding refrigerant from the refrigerant reservoir to the working chamber (104) by means of the injector (118) at a pressure that is at least 4 bar and preferably at least 5 bar above the discharge pressure of the refrigerant compressor (102).

3. Cooling circuit (100) according to either of the preceding claims, wherein the heat exchanger (106) is a condenser or gas cooler.

4. Cooling circuit (100) according to one of the preceding claims, wherein the feed unit (114) is configured for feeding substantially single-phase refrigerant from the refrigerant reservoir to the working chamber (104) by means of the injector (118), and / or wherein the feed unit (114) is configured for feeding refrigerant from the refrigerant reservoir to the working chamber (104) by means of the injector (118) in a liquid or supercritical state.

5. Cooling circuit (100) according to one of the preceding claims, wherein the injector (118) has at least one injection nozzle (128).

6. Cooling circuit (100) according to one of the preceding claims, wherein the injector (118) is configured for distributing the refrigerant within the working chamber (104) and / or for spraying the refrigerant onto a refrigerant-compressor wall (132), delimiting the working chamber (104), of the refrigerant compressor (102), in particular a cylinder wall.

7. Cooling circuit (100) according to one of the preceding claims, wherein the injector (118) has a valve (130), wherein the refrigerant compressor (102) has at least one valve plate (124), wherein the valve (130) is integrated into the valve plate (124) or is adjacent to the valve plate (124).

8. Cooling circuit (100) according to one of the preceding claims, further comprising a control unit (120), wherein the control unit (120) is configured for temporally controlling the feeding of the refrigerant to the working chamber (104) by means of the injector (118), wherein the temporal control involves in particular a time and / or an extent of the feeding of the refrigerant to the working chamber (104) by means of the injector (118).

9. Cooling circuit (100) according to the preceding claim, wherein the control unit (120) is configured for controlling the feeding of the refrigerant to the working chamber (104) by means of the injector (118) on the basis of at least one parameter selected from the group consisting of: pressure in the working chamber (104), temperature in the working chamber (104), crank angle position of the refrigerant compressor (102), suction temperature of the refrigerant compressor (102), suction pressure of the refrigerant compressor (102), high temperature in the cooling circuit (100) and high pressure in the cooling circuit (100), and / or wherein the control unit (120) is configured for controlling the feeding of the refrigerant to the working chamber (104) by means of the injector (118) as a continuous injection quantity, increasing towards a top dead centre, of the refrigerant, and / or wherein the control unit (120) is configured for controlling the feeding of the refrigerant to the working chamber (104) by means of the injector (118) during an expansion operation of the refrigerant compressor (102), during a compression operation of the refrigerant compressor (102) and / or at a plurality of times during all the working cycles of the refrigerant compressor (102).

10. Cooling circuit (100) according to one of the preceding claims, further comprising a post-cooler (122) for cooling the refrigerant from the refrigerant reservoir, in particular for cooling to a temperature which is substantially identical to an ambient temperature of the cooling circuit (100), wherein the post-cooler (122) is preferably arranged between the high-pressure pump (116) and the injector (118).

11. Cooling circuit (100) according to the preceding claim, wherein the refrigerant compressor (102) has a refrigerant-compressor housing, wherein the high-pressure pump (116) is integrated in the refrigerant-compressor housing.

12. Cooling circuit (100) according to one of the preceding claims, wherein the refrigerant compressor (102) is a reciprocating-piston compressor with at least one valve plate (124) and with at least one piston (126), wherein the injector (118) is integrated into the valve plate (124) or is arranged on the refrigerant compressor (102) so as to be adjacent to the valve plate (124).

13. Method for operating a cooling circuit (100), in particular a cooling circuit according to one of the preceding claims, wherein the cooling circuit (100) has a refrigerant compressor (102) with at least one working chamber (104), has a heat exchanger (106) with a fluid-collecting chamber (108), wherein the fluid-collecting chamber (108) is configured for forming a refrigerant reservoir of refrigerant, and has a feed unit (114), wherein the feed unit (114) is connected to the fluid-collecting chamber (108) and the refrigerant compressor (102), wherein the feed unit (114) has a high-pressure pump (116) and an injector (118), wherein the method comprises: - sucking in a refrigerant by means of the refrigerant compressor (102), - compressing the refrigerant by means of the refrigerant compressor (102), - cooling, in particular re-cooling and / or liquefying, the refrigerant by means of the heat exchanger (106), - feeding the cooled refrigerant to the fluid-collecting chamber (108), and - feeding refrigerant from the refrigerant reservoir of the fluid-collecting chamber (108) to the working chamber (104) by means of the injector (118) at a pressure above a discharge pressure of the refrigerant compressor (102).

14. Method according to the preceding claim, wherein the refrigerant from the refrigerant reservoir is fed to the working chamber (104) by means of the injector (118) at a pressure that is at least 4 bar and preferably at least 5 bar above the discharge pressure of the refrigerant compressor (102).

15. Method according to either of the two preceding claims, wherein the refrigerant from the refrigerant reservoir is fed to the working chamber (104) by means of the injector (118) in a substantially single-phase state, and / or wherein the refrigerant from the refrigerant reservoir is fed to the working chamber (104) by means of the injector (118) in a liquid or supercritical state.