Circuit process system and method for operating a circuit process system

Abstract

The invention relates to a circuit process system (1), comprising: a main circuit (A) which comprises: a working device (W) which is designed to be driven by a coolant and to perform work; a conveying device (P1) which is designed to convey the coolant to the working device (W); and a condensing portion (K) which is arranged between the working device (W) and conveying device (P1) and is designed to convert gaseous coolant exiting the working device (W) in the direction of the conveying device (P1) into liquid coolant; wherein for the efficient provision of work, the circuit process system (1) further comprises: a branch portion (B) which is designed to branch some of the liquid coolant off from the main circuit (A) downstream of the conveying device (P1) and supply said coolant to the condensing portion (K) with a higher vapour pressure than the pressure of the gaseous coolant exiting the working device (W).

Description

[0001] Cyclic process system and method for operating a cycle process system

[0002] The present invention relates to a cycle system operable with a refrigerant and a method for operating such a cycle system.

[0003] Growing energy demand combined with increasing environmental requirements requires efficient energy systems. Circulation systems powered by refrigerants are already known. These are characterized by the various changes of state the refrigerant undergoes, during which the refrigerant remains in the system and is not lost. US Pat. No. 5,467,600 A shows a thermal cycle system in which a refrigerant is conveyed from a delivery cylinder through an evaporator as the evaporation section, subsequently expands in a movement-providing cylinder, then flows through a condenser as the condensation section, and then flows back into the delivery cylinder, which then conveys it to the evaporator under pressure.

[0004] However, such a cyclic process system with phase transition is not suitable for performing mechanical work on the surroundings. Rather, in the known system, energy is absorbed in the form of heat and released as heat elsewhere.

[0005] The object of the present invention is to provide a cycle system that can efficiently perform work on the environment.

[0006] This object is achieved according to the invention by a cycle process system having the features of claim 1.

[0007] A first aspect provides a cycle system comprising: a main circuit comprising: a working device configured to be driven by a refrigerant and to perform work, preferably mechanically; a conveying device configured to convey the refrigerant to the working device; and a condensing section arranged between the working device and the conveying device and configured to convert gaseous refrigerant exiting the working device into liquid refrigerant toward the conveying device. The cycle system further comprises a branch section configured to branch off a portion of the liquid refrigerant from the main circuit downstream of the conveying device and to supply it to the condensing section at a higher vapor pressure than the pressure of the gaseous refrigerant exiting the working device.

[0008] According to this aspect, the working device can efficiently perform work on the environment. In particular, it can provide kinetic energy, for example for vehicles. In order to make the phase transformation between the liquid and gaseous phases of the refrigerant efficient, a branch section is provided which branches off a portion of the refrigerant downstream of the conveying device. In the branch section, the vapor pressure can be increased so that the vapor pressure is higher than that of the liquid refrigerant downstream of the conveying device in the main circuit and higher than the (static) pressure of the gaseous refrigerant exiting the working device. When the liquid refrigerant from the branch section and the gaseous refrigerant combine, the liquid refrigerant tends to become gaseous due to the relatively high vapor pressure.Due to the Joule-Thomson effect, the liquid refrigerant can transform into cold, frozen refrigerant, thus creating a solid phase. This frozen refrigerant can eventually cause the gaseous refrigerant from the working device to transform into the liquid phase, and in the process, become liquid again, so that after the condensation stage, only the liquid phase remains.

[0009] In particular, the cycle system is characterized by the fact that a cold source can be generated within the cycle system itself via the branch section, in the form of frozen refrigerant, which causes the liquefaction of the gaseous refrigerant escaping from the working equipment. In other words, it is not necessary to release heat to the environment to liquefy the gaseous refrigerant. Instead, an internal heat exchange between the gaseous refrigerant and the cold source generated in the cycle system can be used to generate liquid refrigerant. The cycle system can thus exclusively cool the environment. The fundamental laws of thermodynamics are nevertheless maintained, since heat in the cycle system always flows from hot to cold.

[0010] The vapor pressure of the supplied liquid refrigerant may be at least 5 bar, preferably at least 10 bar, more preferably at least 20 bar higher than the static pressure of the refrigerant exiting the working device (corresponding to the refrigerant flowing to the condensation section).

[0011] This pressure difference occurs particularly at the point where the liquid refrigerant and the gaseous refrigerant come together.

[0012] The vapor pressure can be determined using known methods, for example by measurement or calculation.

[0013] It should be noted that the subject of the present invention can of course be the above cycle system comprising the refrigerant.

[0014] In the above cycle system, the main circuit may include an evaporation section arranged downstream of the conveying device and upstream of the working device and configured to evaporate the liquid refrigerant exiting from the conveying device toward the working device.

[0015] The energy to be supplied to the main circuit can only be provided by means of a heat supply device that supplies heat to the liquid refrigerant in the evaporation section in order to evaporate it.

[0016] Advantageously, said heat supply device is part of a heat exchanger through which a heat transfer fluid flows to supply heat. This allows the heat transfer fluid to be cooled. The heat transfer fluid can be liquid water, such as seawater, for example. With the cycle system, even low temperatures of a maximum of 25°C, preferably a maximum of 20°C, and even more preferably a maximum of 10°C, are sufficient for the refrigerant to evaporate. Thus, cooling performance can be achieved even at low temperatures.

[0017] Preferably, the conveying device is driven by the working device. This allows for further efficiency improvements. In particular, no external energy source needs to be provided. In other words, part of the mechanical energy generated in the working device is used to convey the liquid refrigerant and to generate the cooling source via the branch section.

[0018] The working device and / or conveying device can be linearly acting elements, for example double-acting cylinders.

[0019] Preferably, the branch section has a branch section heat supply device, which is preferably part of a heat exchanger, which is designed to increase the vapor pressure of the refrigerant in the branch section.

[0020] Thus, the vapor pressure can be easily increased, while the static pressure in the branch section can be equal to the pressure of the refrigerant exiting the conveying device. If a heat exchanger is used, the cooling capacity can be further increased using a heat transfer fluid. The heat transfer fluid is preferably the same (from the same source) as that of the above-mentioned heat exchanger for the evaporation section.

[0021] Alternatively or additionally, the condensation section may comprise a condensation heat supply device, preferably part of a heat exchanger, designed to supply heat to a mixture resulting from the addition of the liquid refrigerant to the gaseous refrigerant in order to liquefy it. This can ensure that any remaining frozen refrigerant is liquefied and does not impair operation. Furthermore, when using a heat exchanger, the cooling capacity of a heat transfer fluid can be increased. The heat transfer fluid may be the same as at least one or both of the heat transfer fluids used for the above-mentioned heat exchangers.

[0022] Preferably, the cycle system further comprises an auxiliary heating circuit which provides heat to the liquefaction heat supply device.

[0023] Thus, heat can be provided by a fluid flowing in the auxiliary heating circuit. This fluid can be specifically modified to supply heat.

[0024] Preferably, the auxiliary heating circuit is arranged so that part of the refrigerant can flow through it.

[0025] In other words, the auxiliary heating circuit can be fluidly coupled to the main circuit or the branch section, allowing a portion of the refrigerant to flow through it. This reduces the complexity of the system because the refrigerant can be used as a heat transfer fluid.

[0026] It is preferred that the auxiliary heating circuit (C) is designed to branch off refrigerant from the branch section, preferably downstream of the branch section heat supply device.

[0027] This further reduces the complexity of the system, as the existing branch section can be used. In particular, the heat transfer fluid can be heated by the branch section heat supply device and transfer this heat to the mixture.

[0028] Alternatively, the auxiliary heating circuit can be arranged so that it is fluidly decoupled from the main circuit and the branch section.

[0029] In other words, the auxiliary heating circuit can be fluidly coupled to the main circuit and the branch section. This allows the auxiliary heating circuit to be specifically designed to heat the mixture, reducing pressure losses in the refrigerant and disruptions. The same refrigerant can flow in the auxiliary heating circuit as in the main circuit. However, a different refrigerant can also flow through the auxiliary heating circuit.

[0030] It is advantageous if the branch section and / or the auxiliary heating circuit are energetically coupled to the main circuit. In other words, part of the work performed by the working device can be used to drive the fluid flowing in the branch section and the auxiliary heating circuit, respectively.

[0031] For example, the conveyor system can be mechanically coupled to the work equipment. A heating auxiliary circuit conveyor system can also be mechanically coupled to the work equipment.

[0032] According to yet another aspect, the main circuit downstream of the working device may have a separating device through which only liquid refrigerant can flow towards the conveying device.

[0033] This ensures that only liquid refrigerant is pumped in the pumping system.

[0034] A further aspect provides a method for operating the cycle system according to at least one of the preceding aspects, wherein the cycle system is operated with a refrigerant, and wherein the branch section supplies the liquid refrigerant to the condensation section in such a way that a frozen refrigerant is at least partially produced.

[0035] According to this method, the solid, frozen refrigerant can be provided as a cold source that liquefies the gaseous refrigerant in the condensing section. Thus, the refrigerant can be liquefied efficiently.

[0036] Carbon dioxide is preferably used as a refrigerant.

[0037] With carbon dioxide, frozen carbon dioxide, also known as dry ice, can be reliably produced. It has a low temperature and can therefore serve as a cooling source. Furthermore, relatively low-temperature heat transfer fluids, as described above, are sufficient for evaporation.

[0038] The process can be operated in such a way that the conditions described above are established. For this purpose, the cyclic process system can have an electronic control device that carries out the above process in the cyclic process system.

[0039] The above aspects will now be described in detail with reference to the accompanying drawings.

[0040] Fig. 1 shows an embodiment of a cycle system.

[0041] Fig. 2 shows a modification of the embodiment.

[0042] Fig. 3 shows a pH diagram of the main circuit. The illustrated cycle system 1 has a main circuit, labeled A. Furthermore, the cycle system 1 has a branch section B, which can be considered a first auxiliary circuit, and an auxiliary heating circuit C.

[0043] The cycle system comprises a piping system through which a refrigerant, preferably CO2 (carbon dioxide), can flow. Each of the circuits A, B, and C is formed by piping and other devices described below.

[0044] The main circuit has a conveying device P1 that conveys completely liquid refrigerant under pressure into an evaporation section V. In the evaporation section V, which has an evaporator and a heat supply device as part of a heat exchanger WT1, the liquid refrigerant is evaporated. The pressure can be set to, for example, 45 bar and the temperature to, for example, 10°C.

[0045] The completely gaseous refrigerant exits the evaporation section V and drives a downstream working device W, which can be mechanically coupled to the conveying device P1 for energy transfer. In other words, the working device W can drive the conveying device P1. A pressure regulator R1 is arranged between the evaporation section V and the working device W. This pressure regulator R1 can keep the pressure of the gaseous refrigerant constant at a setpoint, for example, 45 bar.

[0046] The gaseous refrigerant expanded in the working device W flows downstream into the condensing section K at, for example, 20 bar and -20 °C. The condensing section K may include a condenser and a condensing heat supply device as part of a heat exchanger WT3. The condenser may be an adiabatic vessel into which the gaseous refrigerant flows.

[0047] The liquefied refrigerant flows, for example, at 20 bar and -20 °C via a separator R4 into a reservoir R. From there, the liquid refrigerant flows into the delivery device P1. The delivery device delivers the refrigerant to, for example, at least the pressure at the end of the evaporation section V (45 bar), preferably above this pressure, in this case 46 bar.

[0048] Furthermore, branch section B is provided downstream of the conveying device P1 in such a way that it branches off the pressurized liquid refrigerant from the main circuit A. The mass flows of refrigerant in branch section B and the refrigerant flowing on in the main circuit A can be equal. A branch section heat supply device WT2, designed as a heat exchanger, is provided in branch section B. The heat supply device WT2 heats the liquid refrigerant in branch section B, for example, to 10 °C at 45 bar, and thus increases the vapor pressure of the refrigerant. The heated liquid refrigerant is fed to the condensation section K downstream of the heat supply device WT2.A mass flow controller R2 is arranged between the heat supply device WT2 and the point of merging with the gaseous refrigerant in the condensation section K (inlet to the condenser), which controls the amount of liquid refrigerant supplied to the condensation section K.

[0049] The condensation section K further comprises a condensation heat supply device WT3, which is designed as a heat exchanger. It can be provided in the condenser.

[0050] To provide heat to the condensation heat supply device WT3, system 1 includes auxiliary heating circuit C, which branches off the heated liquid refrigerant downstream of the branch section heat supply device WT2 and flows it through the heat exchanger WT3. Downstream of the heat exchanger WT3, the refrigerant is supplied to the main circuit A downstream of the conveying device and upstream of the evaporation section V. To reliably return the refrigerant to the main circuit, auxiliary heating circuit C includes an auxiliary circuit conveying device P3, such as a pump. Furthermore, auxiliary heating circuit C includes an auxiliary circuit mass flow controller R3 downstream of the auxiliary circuit conveying device P3, which regulates a mass flow through the heat exchanger WT3.

[0051] A heat transfer fluid conveying device P2, such as a pump, is provided in system 1. It conveys a heat transfer fluid from the same source through the heat exchangers WT1 and WT2. The heat transfer fluid has a higher temperature than the pressurized liquid refrigerant in the main circuit A.

[0052] A mass flow of the heat transfer fluid through the heat exchanger WT1 can be controlled via a mass flow controller R5.

[0053] Furthermore, a mass flow of the heat transfer fluid through the heat exchanger WT2 can be controlled via a mass flow controller R6.

[0054] It should be noted that in the figures, the index "F" indicates the liquid state, and the index "Gas" indicates the gaseous state. Furthermore, in the figures, not only are the respective sections and circles designated by A, B, and C, but at certain points in the cycle system, the combination of mass flows from the circles and sections is also indicated by the letters at these points.

[0055] According to the present invention, energy can be generated from the pressure difference and volume difference between evaporated gaseous refrigerant and liquid refrigerant, which is used to drive the working device. Furthermore, in the closed system 1, a portion of the energy generated in the thermomechanical working device W enables the integration and operation of the branch section B and the auxiliary heating circuit C to create at least one cold source, so that the working gas, which has been adiabatically expanded after work has been performed in the thermomechanical working device W, can be liquefied again. This is made possible by the physical property of carbon dioxide. This is capable of transforming into a cryogenic state and thus into frozen carbon snow (dry ice), which can exist at a temperature of -78.5°C.

[0056] Through the branch section B, liquid CO2 is introduced via the mass flow controller R2 at high pressure, as prevailing downstream of the conveying device P1, and at high vapor pressure into the condenser filled with the adiabatically expanded, gaseous refrigerant via a suitable spatial distribution system using, for example, spray systems in the form of at least one convergent and / or divergent nozzle, or similar. The cycle system can therefore have at least one nozzle, preferably several, by means of which the liquid refrigerant from the branch section is fed to the condensation section. The at least one nozzle can be an atomizing nozzle. The pressure of the gaseous refrigerant in the condenser is, for example, at least 20 bar, here 25 bar, below the vapor pressure of the liquid refrigerant.

[0057] The liquid refrigerant introduced into the condensation section breaks down into droplets due to the higher static pressure. These droplets evaporate in fractions of a second due to the high vapor pressure or differential pressure. In the process, the refrigerant itself extracts the energy required for this process through the phase transition. This can cause the refrigerant to become very cold, resulting in the formation of carbon dioxide snow (-78.5°C).

[0058] The adiabatic expansion of the refrigerant in the working device W can further result in a relatively low temperature in the condensing section K.

[0059] The generation of the cold source in the system enables continuous cooling of the environment.

[0060] The auxiliary circuit pumping device P3 can compensate for pressure losses in the auxiliary heating circuit C.

[0061] It should be noted that the separator R4 can also serve as a pressure adjustment device, allowing the pressure of the refrigerant flowing into the reservoir to be adjusted. The pressure adjustment device can be integrated with the separator, separately from it, or even completely without the separator. The mass flow controller R2 can control the amount of frozen refrigerant produced. Furthermore, the condensing heat supply device WT3 and the auxiliary circuit mass flow controller can ensure the controlled melting of any remaining frozen refrigerant.

[0062] Alternatively, a spatial separation between the adiabatically expanded refrigerant and the liquid refrigerant from branch section B can be provided in the condensing section (adiabatic vessel), as long as the pressure in the condensing section due to the gaseous refrigerant is lower than the vapor pressure. The liquid refrigerant from the branch section does not have to be, but preferably can, fed directly to the gaseous refrigerant coming from the working device. Instead, the refrigerant from the branch section can also be fed to a separate chamber with a pressure lower than the vapor pressure.

[0063] The condensing section K (condenser) can have a level sensor N2 that can monitor the amount of liquid produced. Likewise, a level sensor N3 can be provided in the reservoir R to monitor the fill level in the reservoir.

[0064] Reservoir R stores the liquid refrigerant. Reservoir R can be used to compensate for fluctuations in the mass flow. Furthermore, reservoir R can be used to initially flood system 1 to start the cycle.

[0065] A level sensor N1 may be provided in the evaporation section V (evaporator) to monitor the amount of liquid.

[0066] All level sensors N1 to N3 can transmit signals to an electronic control unit (control device) which can control the control devices R1 to R6 and the conveyor devices P1 to P3.

[0067] Furthermore, the entire system 1 can be equipped with additional sensors and actuators. If operating parameters change, the electronic control unit can control these actuators.

[0068] Some or all of the conveyor devices P1 to P3 may be mechanically coupled to the working device W in order to be driven thereby.

[0069] In Fig. 2, the auxiliary heating circuit C is not branched off downstream of the branch section heat supply device WT2. Rather, the auxiliary heating circuit C is designed to be fluidly decoupled from the main circuit A and the branch section B.

[0070] The auxiliary heating circuit C can be flowed through by the refrigerant as a heat transfer fluid, or by another fluid. Here, the auxiliary heating circuit C is a closed circuit comprising the auxiliary circuit conveying device P3, which can be mechanically (energetically) coupled to the working device W. The auxiliary circuit mass flow controller R3 can also be provided downstream of the auxiliary circuit conveying device P3 and regulates the flow through the heat exchanger WT3.

[0071] Furthermore, an auxiliary circuit heat supply device WT4 is provided upstream of the auxiliary circuit conveying device P3 as a heat exchanger. The heat exchanger can use the same heat transfer fluid (from the same source) as for the heat exchangers WT1 and WT2 as the heat transfer fluid. This heat transfer fluid can be conveyed from the heat transfer fluid conveying device P2 to the heat exchanger WT4 via a mass flow controller P7.

[0072] The invention also relates to a vehicle, in particular a watercraft, which has the cycle system, wherein the working device is arranged to drive the vehicle.

[0073] Seawater can be used as a heat transfer fluid.

[0074] In the above embodiment and in the modification, the working device and the conveying device (here, the pump cylinder) are designed as double-acting cylinders and thus as linear elements. The cylinder of the working device W has a larger cross-section than that of the conveying device P1. However, single-acting cylinders or rotary elements are also conceivable as the conveying device and / or working device. Thus, the conveying device can be a rotary pump and the working device a rotating turbine.

[0075] Fig. 3 shows the pH diagram for the main circuit of system 1 using CO2 as an example. Between points 1 and 2, the conveying / compression takes place through the conveying device P1. This can, for example, be adiabatical, in particular approximately isentropic. Between points 2 and 3, evaporation takes place in the evaporation section V, in particular isobaric. Between points 3 and 4, expansion takes place in the working device W. This can be adiabatical. For the sake of simplicity, an isenthalpic change of state is shown in Fig. 3. Condensation finally takes place between points 4 and 1. A necessary enthalpy reduction of around 270 kJ / kg K can be assumed for liquefaction. Conversely, the cold source generated in the system requires 200 kJ / kg for melting, and 125 kJ / kg for the additional heating from -78.5 °C to the temperature (here: -20 °C) of the refrigerant fed to the conveying device.Thus, condensation can proceed constantly, even if the change of state between 3 and 4 is not isenthalpic. The condensation heat supply device WT3 can be used to completely condense the refrigerant and thus serves to control / regulate, among other things, the pressure in the condensation section.

[0076] The above values ​​are merely examples. For example, the gaseous refrigerant expanded in the working device W can enter the downstream condensing section K at 25 bar and -12 °C. It can then flow into the reservoir at, for example, 25 bar and -15 °C. The temperature of the liquefied refrigerant can be controlled / regulated via the condensing heat supply device WT3.

[0077] "Gaseous" and "liquid" specifically mean completely gaseous and completely liquid, but can also mean only partially gaseous and partially liquid (wet steam). The conveying device specifically conveys completely liquid refrigerant, which is evaporated in the evaporation section, particularly to completely gaseous refrigerant. In the working device, the refrigerant can also be expanded so that it exits the working device completely or partially in gaseous form and is then completely liquefied.

[0078] In the above disclosure, the term “regulate” and its variations also includes “control.”

Claims

Claims:

1. Cyclic process system (1), comprising: - a main circuit (A) comprising: - a working device (W) which is designed to be driven by a refrigerant and to perform, preferably mechanical, work, - a conveying device (P1) designed to convey the refrigerant to the working device (W), and - a condensation section (K) arranged between the working device (W) and the conveying device (P1) and designed to convert gaseous refrigerant emerging from the working device (W) into liquid refrigerant towards the conveying device (P1); wherein the cycle system (1) further comprises: - a branch section (B) which is designed to branch off a part of the liquid refrigerant downstream of the conveying device (P1) from the main circuit (A) and to supply it to the condensing section (K) with a higher vapor pressure than the pressure of the gaseous refrigerant emerging from the working device (W).

2. Cycle system (1) according to claim 1, wherein the branch section (B) has a branch section heat supply device (WT2), which is preferably part of a heat exchanger, which is designed to increase the vapor pressure of the refrigerant in the branch section (B).

3. Cycle system (1) according to claim 1 or 2, wherein the liquefaction section (K) has a liquefaction heat supply device (WT3), which is preferably part of a heat exchanger, which is designed to supply heat to a mixture resulting from the supply of the liquid refrigerant to the gaseous refrigerant in order to liquefy it.

4. Cycle system (1) according to claim 3, wherein the cycle system (1) further comprises an auxiliary heating circuit (C) which provides heat to the liquefaction heat supply device (WT3).

5. Cycle system (1) according to claim 4, wherein the auxiliary heating circuit (C) is arranged so that a part of the refrigerant can flow through it.

6. Cycle system (1) according to claim 5, wherein the auxiliary heating circuit (C) is designed to branch off refrigerant from the branch section, preferably downstream of the branch section heat supply device (WT2).

7. Cycle system (1) according to claim 4, wherein the auxiliary heating circuit (C) is arranged so that it is fluidly decoupled from the main circuit (A) and the branch section (B).

8. Cycle process system (1) according to at least one of the preceding claims, wherein the main circuit (A) downstream of the working device (W) has a separating device (R4) through which only liquid refrigerant can flow towards the conveying device (P1).

9. A method for operating the cycle system (1) according to at least one of the preceding claims, wherein the cycle system (1) is operated with a refrigerant, and wherein the branch section (B) supplies the liquid refrigerant to the condensation section in such a way that a frozen refrigerant is at least partially produced.

10. The method according to claim 9, wherein carbon dioxide is used as the refrigerant.

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