Rankine cycle system and pressure reduction control method

Abstract

The application provides a Rankine cycle system and a pressure reduction control method. The Rankine cycle system comprises a circulation pipeline, a liquid storage tank, an evaporator, an expander and a condenser. The liquid storage tank, the evaporator, the expander and the condenser are sequentially arranged on the circulation pipeline. The Rankine cycle system further comprises a fluidic device having a flow inlet, a flow outlet and a suction inlet. The flow inlet is connected with a first communication port of the circulation pipeline. The first communication port is located between an inlet of the expander and an outlet of the liquid storage tank. The flow outlet is connected with a second communication port of the circulation pipeline. The second communication port is located between an outlet of the expander and an inlet of the condenser. The suction inlet is connected with a gas outlet of the liquid storage tank. The Rankine cycle system solves the problem that in the prior art, due to incomplete condensation of working medium after the condenser of the Rankine cycle system, gaseous working medium enters the liquid storage tank, thereby causing the pressure in the liquid storage tank to increase.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and more specifically, to a Rankine cycle system and a pressure reduction control method. Background Technology

[0002] During the Rankine cycle system test, the working fluid after the condenser was not completely condensed, resulting in a small amount of gaseous working fluid remaining in the entire pipeline. This gaseous working fluid entered the liquid storage tank, causing the pressure inside the tank to rise. This resulted in poor exhaust of the expander, greatly reducing the power output of the expander and reducing the system efficiency.

[0003] Currently, the technical means used to stabilize system pressure is to connect the storage tank to compressed air or nitrogen at a certain pressure externally, so as to introduce or output compressed air or nitrogen in real time. In other words, the storage tank needs to be connected to compressed air or nitrogen at a certain pressure during system operation in order to balance the pressure inside the storage tank and achieve the function of pressure stabilization.

[0004] However, using compressed air or nitrogen to balance the pressure of the storage tank requires the real-time supply or output of compressed air or nitrogen, which places certain requirements on the system operation site. It requires that there be compressed air or nitrogen at a certain pressure. Without compressed air or nitrogen, the system will not be able to maintain the normal pressure or the preset pressure cannot be guaranteed. Summary of the Invention

[0005] The main objective of this invention is to provide a Rankine cycle system and a pressure reduction control method to solve the problem in the prior art where incomplete condensation of the working fluid after the condenser in the Rankine cycle system causes gaseous working fluid to enter the liquid storage tank, resulting in increased pressure inside the liquid storage tank.

[0006] To achieve the above objectives, according to one aspect of the present invention, a Rankine circulation system is provided, comprising a circulation pipeline, a liquid storage tank, an evaporator, an expander, and a condenser, wherein the liquid storage tank, evaporator, expander, and condenser are sequentially arranged on the circulation pipeline. The Rankine circulation system further comprises: an ejector having an inlet, an outlet, and a suction port; the inlet being connected to a first connecting port of the circulation pipeline, the first connecting port being located between the inlet of the expander and the outlet of the liquid storage tank; the outlet being connected to a second connecting port of the circulation pipeline, the second connecting port being located between the outlet of the expander and the inlet of the condenser; and the suction port being connected to the gas outlet of the liquid storage tank.

[0007] Furthermore, the Rankine circulation system also includes: a first connecting pipe, the first end of which is connected to a first communication port, and the second end of which is connected to a flow inlet; and a control valve, which is disposed on the first connecting pipe.

[0008] Furthermore, the Rankine circulation system also includes: a second connecting pipe, the first end of which is connected to the outlet and the second end of which is connected to the second communication port; and a first check valve, which is provided on the second connecting pipe to allow fluid to flow from the first end to the second end of the second connecting pipe.

[0009] Furthermore, the Rankine circulation system also includes: a third connecting pipe, the first end of which is connected to the outlet and the second end of which is connected to the inlet; and a second one-way valve, which is installed on the third connecting pipe to allow gas to flow from the first end to the second end of the third connecting pipe.

[0010] Furthermore, the Rankine circulation system also includes: a pump body disposed on the circulation pipeline and located between the liquid storage tank and the evaporator; wherein, the first connection port is located between the pump body and the evaporator; or, the first connection port is located between the evaporator and the expander.

[0011] Furthermore, the Rankine circulation system also includes a pressure sensor, which is installed on the reservoir to detect the pressure value inside the reservoir.

[0012] Furthermore, the inlet of the liquid storage tank is located at the top of the liquid storage tank, and the outlet is located on the side wall of the liquid storage tank and at the top of the side wall.

[0013] According to another aspect of the present invention, a pressure reduction control method is provided, applicable to the above-described Rankine cycle system. The pressure reduction control method includes: acquiring the pressure value in the storage tank; determining the relationship between the pressure value and a pressure threshold P; controlling the ejector to operate when the pressure value is greater than the pressure threshold P; and controlling the ejector to stop operating when the pressure value is less than or equal to the pressure threshold P.

[0014] Furthermore, the pressure reduction control method is applicable to the aforementioned Rankine cycle system. When the pressure value is greater than the pressure threshold P, the ejector is controlled to operate; when the pressure value is less than or equal to the pressure threshold P, the ejector is controlled to stop operating. This method includes: when the pressure value is greater than the pressure threshold P, the control valve is opened; when the pressure value is less than or equal to the pressure threshold P, the control valve is closed.

[0015] Furthermore, the pressure reduction control method also includes: calculating the pressure difference ΔP between the pressure value and the pressure threshold P; adjusting the opening degree of the control valve according to the ratio between the pressure difference ΔP and the pressure threshold P; wherein the opening degree of the control valve is positively correlated with the ratio between the pressure difference ΔP and the pressure threshold P.

[0016] According to the technical solution of this invention, the Rankine cycle system includes a circulation pipeline, a storage tank, an evaporator, an expander, a condenser, and an ejector. The ejector has an inlet, an outlet, and a suction port. The inlet is connected to a first connecting port of the circulation pipeline, the outlet is connected to a second connecting port of the circulation pipeline, and the suction port is connected to the outlet of the storage tank. The high-pressure working fluid flows sequentially through the first connecting port and the inlet into the ejector, creating a negative pressure within the ejector. This negative pressure causes the gaseous working fluid in the storage tank to flow sequentially through the outlet and the suction port and be drawn into the ejector. At this time, the gaseous working fluid and the high-pressure working fluid mix in the ejector and then flow sequentially through the outlet, the second connecting port, and the inlet of the condenser into the condenser. The mixed working fluid undergoes heat exchange and cooling in the condenser before entering the storage tank. The gaseous working fluid in the storage tank is drawn out by the ejector, thereby reducing the pressure inside the storage tank. At the same time, the gaseous working fluid flows out of the ejector and is added back into the entire cycle, avoiding waste caused by the discharge of working fluid. This solves the problem in the existing technology where the working fluid after the condenser of the Rankine cycle system is not completely condensed, causing the gaseous working fluid to enter the storage tank and thus increasing the pressure inside the storage tank. This also avoids a reduction in the power output of the expander and the efficiency of the Rankine cycle system, reduces costs, avoids environmental pollution, saves downtime for venting, and reduces the labor intensity of users. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0018] Figure 1 A schematic diagram of an embodiment of the Rankine cycle system according to the present invention is shown (the first connection port is located between the pump body and the evaporator);

[0019] Figure 2 A schematic diagram of another embodiment of the Rankine cycle system according to the present invention is shown (the first connection port is located between the evaporator and the expander);

[0020] Figure 3 A flowchart of a step-down control method for a Rankine cycle system according to the present invention is shown.

[0021] The above figures include the following reference numerals:

[0022] 10. Circulation pipeline; 20. Liquid storage tank; 21. Gas outlet; 30. Evaporator; 40. Expander; 50. Condenser; 60. Ejector; 61. Inlet; 62. Outlet; 63. Suction port; 70. First connecting pipe; 80. Control valve; 90. Second connecting pipe; 100. First check valve; 110. Third connecting pipe; 120. Second check valve; 130. Pump body; 140. Pressure sensor. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0025] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0026] This invention provides a Rankine cycle system; please refer to [reference needed]. Figure 1 and Figure 2 The system includes a circulation pipeline 10, a liquid storage tank 20, an evaporator 30, an expander 40, and a condenser 50. The liquid storage tank 20, evaporator 30, expander 40, and condenser 50 are sequentially arranged on the circulation pipeline 10. The Rankine circulation system also includes an ejector 60, which has an inlet 61, an outlet 62, and a suction port 63. The inlet 61 is connected to a first connecting port of the circulation pipeline 10, which is located between the inlet of the expander 40 and the outlet of the liquid storage tank 20. The outlet 62 is connected to a second connecting port of the circulation pipeline 10, which is located between the outlet of the expander 40 and the inlet of the condenser 50. The suction port 63 is connected to the air outlet 21 of the liquid storage tank 20.

[0027] The Rankine cycle system of the present invention includes a circulation pipeline 10, a storage tank 20, an evaporator 30, an expander 40, a condenser 50, and an ejector 60. The ejector 60 has an inlet 61, an outlet 62, and a suction inlet 63. The inlet 61 is connected to a first connecting port of the circulation pipeline 10, the outlet 62 is connected to a second connecting port of the circulation pipeline 10, and the suction inlet 63 is connected to the outlet 21 of the storage tank 20. The high-pressure working fluid flows sequentially through the first connecting port and the inlet 61 into the ejector 60, creating a negative pressure within the ejector 60. This negative pressure causes the gaseous working fluid in the storage tank 20 to flow sequentially through the outlet 21 and the suction inlet 63 and be drawn into the ejector 60. At this time, the gaseous working fluid and the high-pressure working fluid mix in the ejector 60 and then flow sequentially through the outlet 62, the second connecting port, and the inlet of the condenser 50 into the condenser 50. The mixed working fluid undergoes heat exchange and cooling in the condenser 50 before entering the storage tank 20. The gaseous working fluid in the storage tank 20 is drawn out by the ejector 60, thereby reducing the pressure inside the storage tank 20. The gaseous working fluid then re-enters the condenser 50 for heat exchange and condensation into liquid. Simultaneously, the gaseous working fluid flows out of the ejector 60 and is added back into the entire cycle, avoiding waste caused by the discharge of working fluid. This solves the problem in the prior art where incomplete condensation of the working fluid after the condenser in the Rankine cycle system leads to the gaseous working fluid entering the storage tank, resulting in increased pressure inside the storage tank. This also avoids a reduction in the expander's power output and the efficiency of the Rankine cycle system, reduces costs, avoids environmental pollution, saves downtime for venting, and reduces the user's workload.

[0028] Specifically, in the Rankine cycle system, the working fluid flows sequentially through the storage tank 20, evaporator 30, expander 40, and condenser 50 before returning to the storage tank 20, completing the entire cycle. The ejector 60 also includes a nozzle, a suction chamber, and a diffuser. The inlet 61, outlet 62, and suction port 63 are all connected to the suction chamber. The high-pressure working fluid flows sequentially into the inlet 61 and nozzle before entering the suction chamber, where a vacuum is created. This allows the low-pressure gaseous working fluid in the storage tank 20 to be drawn in through the suction port 63. The gaseous working fluid and the high-pressure working fluid are mixed in the suction chamber and then flow sequentially through the diffuser and outlet 62 before exiting the ejector 60. This invention uses the ejector 60 to replace the bulky pressure stabilizing device, adjusting the pressure inside the storage tank 20 to ensure pressure stability, thus increasing the integration of the Rankine cycle system.

[0029] Specifically, the main components of a Rankine cycle system include an evaporator 30, an expander 40, a condenser 50, a receiver 20, and corresponding piping connections. The system can also be equipped with a number of sensors, such as temperature sensors, pressure sensors, flow meters, expander speed sensors, and vibration sensors, as well as a number of electric valves, manual valves, filters, and expander bypass branches as needed. The system can use organic refrigerants, including R245fa, R1233zd, and R1234yf, as the circulating refrigerant, or alkanes such as cyclopentane, but is not limited to these. Generally, a Rankine cycle system is an independent, sealed system with no external flow of the refrigerant.

[0030] In this embodiment, the Rankine circulation system further includes: a first connecting pipe 70, the first end of which is connected to a first communication port, and the second end of which is connected to a flow inlet 61; and a control valve 80, which is disposed on the first connecting pipe 70.

[0031] Specifically, the high-pressure working fluid flows through the first connecting port into the first connecting pipe 70, and after flowing out of the first connecting pipe 70, it enters the ejector 60 through the inlet 61. The opening and closing of the control valve 80 can control the on / off of the first connecting pipe 70, and the opening degree of the control valve 80 can be adjusted, so that the user can flexibly adjust the flow rate of the high-pressure working fluid flowing into the ejector 60 according to the pressure in the liquid storage tank 20, thereby adjusting the flow rate of the gaseous working fluid sucked into the liquid storage tank 20 by the ejector 60.

[0032] Optionally, control valve 80 is an electric valve.

[0033] In this embodiment, the Rankine circulation system further includes: a second connecting pipe 90, the first end of which is connected to the outlet 62, and the second end of which is connected to the second communication port; and a first one-way valve 100, which is disposed on the second connecting pipe 90 to allow fluid to flow from the first end to the second end of the second connecting pipe 90.

[0034] Specifically, the mixed working fluid enters the second connecting pipe 90 from the outlet 62, and flows from the second connecting pipe 90 through the second connecting port and the inlet of the condenser 50 into the condenser 50; the first one-way valve 100 can ensure that the working fluid can only flow from the first end to the second end of the second connecting pipe 90, that is, to prevent the working fluid from flowing back from the condenser 50 into the ejector 60, which would affect the system circulation.

[0035] In this embodiment, the Rankine circulation system further includes: a third connecting pipe 110, the first end of which is connected to the air outlet 21, and the second end of which is connected to the air inlet 63; and a second one-way valve 120, which is disposed on the third connecting pipe 110 to allow gas to flow from the first end of the third connecting pipe 110 to the second end.

[0036] Specifically, the gaseous working fluid enters the third connecting pipe 110 from the outlet 21, and flows from the third connecting pipe 110 through the suction port 63 into the ejector 60; the second one-way valve 120 can ensure that the gaseous working fluid can only flow from the first end to the second end of the third connecting pipe 110, that is, to prevent the gaseous working fluid from flowing back into the liquid storage tank 20 from the ejector 60, which would cause the pressure of the liquid storage tank 20 to increase.

[0037] Specifically, to prevent leakage of the working fluid, sealing structures, such as O-rings, are provided between the first connecting port and the first connecting pipe 70, between the second connecting port and the second connecting pipe 90, and between the air outlet 21 and the third connecting pipe 110.

[0038] In this embodiment, the Rankine circulation system further includes: a pump body 130, which is disposed on the circulation pipeline 10 and located between the liquid storage tank 20 and the evaporator 30; wherein, the first connection port is located between the pump body 130 and the evaporator 30.

[0039] Specifically, the pump body 130 is used to pressurize the working medium flowing out of the liquid storage tank 20, so that the working medium flowing into the ejector 60 is a high-pressure working medium. At the same time, since the pressure of the second connection port is relatively small, it is conducive to the smooth flow of the high-pressure working medium into the ejector 60, thereby ensuring that the high-pressure working medium can form a negative pressure in the ejector 60, so that the ejector 60 can smoothly draw out the gaseous working medium in the liquid storage tank 20.

[0040] In another embodiment, the first connection port is located between the evaporator 30 and the expander 40. The working fluid flowing out of the storage tank 20 is heated by the evaporator 30 and pressurized by the pump body 130 to become a high-temperature and high-pressure working fluid. The high-temperature and high-pressure working fluid flows into the ejector 60, so that the gaseous working fluid in the storage tank 20 is successfully drawn out.

[0041] In this embodiment, the Rankine circulation system further includes a pressure sensor 140, which is installed on the liquid storage tank 20 to detect the pressure value inside the liquid storage tank 20.

[0042] Specifically, the pressure sensor 140 is used to detect the pressure value inside the liquid storage tank 20, so that the user can flexibly adjust the flow rate of the high-pressure working fluid flowing into the ejector 60 according to the pressure inside the liquid storage tank 20, thereby adjusting the flow rate of the gaseous working fluid sucked into the liquid storage tank 20 by the ejector 60, and thus accurately adjusting the pressure inside the liquid storage tank 20.

[0043] In this embodiment, the inlet of the liquid storage tank 20 is located at the top of the liquid storage tank 20, and the vent 21 is provided on the side wall of the liquid storage tank 20 and located at the top of the side wall.

[0044] Specifically, the gaseous working fluid, being lighter, floats to the top of the storage tank 20. The outlet 21 is located on the side wall of the storage tank 20 and at the top of the side wall, which helps the ejector 60 to draw out the gaseous working fluid. Furthermore, the inlet and outlet 21 of the storage tank 20 are spaced apart, one located at the top of the storage tank 20 and the other at the side wall of the storage tank 20, to prevent the outlet 21 from drawing in working fluid flowing into the inlet of the storage tank 20.

[0045] In practice, since the Rankine cycle system has a small amount of gaseous working fluid after condensation during operation, the flow rate is also small. Therefore, the pipes used in the first connecting pipe 70, the second connecting pipe 90, and the third connecting pipe 110 in this invention can all be made with small-diameter pipes, that is, pipes with a diameter of less than 8mm. This setting facilitates pipe modification and is easy to implement.

[0046] Specifically, the connections of the first connecting pipe 70, the second connecting pipe 90, and the third connecting pipe 110 to the circulation pipeline 10 are all equipped with sealing structures to prevent fluid leakage. Optionally, the sealing structure is a rubber ring.

[0047] Specifically, the Rankine cycle system is used for waste heat recovery from the exhaust of engines or diesel engines.

[0048] This invention also provides a step-down control method, please refer to [reference needed]. Figure 3 The step-down control method, applicable to the Rankine cycle system in the above embodiments, includes:

[0049] Step S100: Obtain the pressure value inside the storage tank 20;

[0050] Step S200: Determine the relationship between the pressure value and the pressure threshold P. When the pressure value is greater than the pressure threshold P, control the ejector 60 to run; when the pressure value is less than or equal to the pressure threshold P, control the ejector 60 to stop running.

[0051] The pressure reduction control method of the present invention includes: using a pressure sensor 140 to obtain the pressure value inside the liquid storage tank 20; the user determines the relationship between the pressure value and the pressure threshold P; when the pressure value is greater than the pressure threshold P, the ejector 60 is controlled to operate, and the ejector 60 draws in the gaseous working fluid in the liquid storage tank 20, thereby regulating the pressure inside the liquid storage tank 20; when the pressure value is less than or equal to the pressure threshold P, the ejector 60 is controlled to stop operating.

[0052] In this embodiment, the method of controlling the ejector 60 to operate when the pressure value is greater than the pressure threshold P and controlling the ejector 60 to stop operating when the pressure value is less than or equal to the pressure threshold P includes: opening the control valve 80 when the pressure value is greater than the pressure threshold P; and closing the control valve 80 when the pressure value is less than or equal to the pressure threshold P.

[0053] In practice, when the pressure value is greater than the pressure threshold P, the control valve 80 is opened to control the ejector 60 to operate, the first connecting pipe 70 is connected, and the high-pressure working fluid flows into the first connecting pipe 70 through the first connecting port. After flowing out of the first connecting pipe 70, it enters the ejector 60 through the inlet 61. The high-pressure working fluid forms a negative pressure in the ejector 60, so that the ejector 60 can smoothly draw out the gaseous working fluid in the liquid storage tank 20 and regulate the pressure in the liquid storage tank 20. When the pressure value is less than or equal to the pressure threshold P, the control valve 80 is closed to control the ejector 60 to stop operating, and the first connecting pipe 70 is disconnected.

[0054] In this embodiment, the pressure reduction control method further includes: calculating the pressure difference ΔP between the pressure value and the pressure threshold P; adjusting the opening degree of the control valve 80 according to the ratio between the pressure difference ΔP and the pressure threshold P; wherein the opening degree of the control valve 80 is positively correlated with the ratio between the pressure difference ΔP and the pressure threshold P. This setting can accurately regulate the pressure value inside the liquid storage tank.

[0055] In practical implementation, the opening coefficient of control valve 80 is K, and the opening degree of control valve 80 is equal to K*ΔP / P. By adjusting the opening coefficient K, the response speed of ejector 60, i.e., the pressure reduction speed in storage tank 20, can be adjusted. The pressure value in storage tank 20 is obtained using pressure sensor 140. The user calculates the pressure difference ΔP between the pressure value and the pressure threshold P. The opening degree of control valve 80 is adjusted according to the ratio between the pressure difference ΔP and the pressure threshold P. When the ratio between the pressure difference ΔP and the pressure threshold P increases, the opening degree of control valve 80 increases accordingly, and the flow velocity of the gaseous working fluid drawn into ejector 60 in storage tank 20 increases, realizing rapid pressure reduction when the pressure in storage tank 20 is high, thereby accurately regulating the pressure in storage tank 20.

[0056] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0057] The Rankine cycle system of the present invention includes a circulation pipeline 10, a storage tank 20, an evaporator 30, an expander 40, a condenser 50, and an ejector 60. The ejector 60 has an inlet 61, an outlet 62, and a suction inlet 63. The inlet 61 is connected to a first connecting port of the circulation pipeline 10, the outlet 62 is connected to a second connecting port of the circulation pipeline 10, and the suction inlet 63 is connected to the outlet 21 of the storage tank 20. The high-pressure working fluid flows sequentially through the first connecting port and the inlet 61 into the ejector 60, creating a negative pressure within the ejector 60. This negative pressure causes the gaseous working fluid in the storage tank 20 to flow sequentially through the outlet 21 and the suction inlet 63 and be drawn into the ejector 60. At this time, the gaseous working fluid and the high-pressure working fluid mix in the ejector 60 and then flow sequentially through the outlet 62, the second connecting port, and the inlet of the condenser 50 into the condenser 50. The mixed working fluid undergoes heat exchange and cooling in the condenser 50 before entering the storage tank 20. The gaseous working fluid in the storage tank 20 is drawn out by the ejector 60, thereby reducing the pressure inside the storage tank 20. At the same time, the gaseous working fluid flows out of the ejector 60 and is added back into the entire cycle, avoiding waste caused by the discharge of working fluid. This solves the problem in the prior art where the working fluid after the condenser of the Rankine cycle system is not completely condensed, causing the gaseous working fluid to enter the storage tank and thus increasing the pressure inside the storage tank. This also avoids a reduction in the power output of the expander and the efficiency of the Rankine cycle system, reduces costs, avoids environmental pollution, saves downtime for venting, and reduces the labor intensity of users.

[0058] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0059] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A Rankine circulation system, comprising a circulation pipeline (10), a liquid storage tank (20), an evaporator (30), an expander (40), and a condenser (50), wherein the liquid storage tank (20), the evaporator (30), the expander (40), and the condenser (50) are sequentially arranged on the circulation pipeline (10), characterized in that, The Rankine cycle system also includes: The ejector (60) has an inlet (61), an outlet (62), and a suction port (63). The inlet (61) is connected to a first connection port of the circulation pipeline (10), which is located between the inlet of the expander (40) and the outlet of the storage tank (20). The outlet (62) is connected to a second connection port of the circulation pipeline (10), which is located between the outlet of the expander (40) and the inlet of the condenser (50). The suction port (63) is connected to the air outlet (21) of the storage tank (20). The ejector (60) also includes a nozzle, a suction chamber, and a diffuser. The inlet (61), the outlet (62), and the suction port (63) are all connected to the suction chamber. The high-pressure working fluid flows into the inlet (61) and the nozzle in sequence and then enters the suction chamber. A vacuum is formed in the suction chamber, so that the low-pressure gaseous working fluid in the liquid storage tank (20) is sucked in from the suction port (63). The gaseous working fluid and the high-pressure working fluid are mixed in the suction chamber and then flow through the diffuser and the outlet (62) in sequence and out of the ejector (60). A pressure sensor (140) is installed on the liquid storage tank (20) to detect the pressure value inside the liquid storage tank (20); The controller (5) is connected to the pressure sensor (140) and the control valve (80) via communication. When the detection value of the pressure sensor (140) is greater than the pressure threshold P, the controller controls the control valve (80) to open. When the detection value is less than or equal to the pressure threshold P, the controller controls the control valve (80) to close. The controller adjusts the opening degree of the control valve (80) according to the pressure difference ΔP between the pressure value and the pressure threshold P, wherein the opening degree of the control valve (80) is positively correlated with the ratio between the pressure difference ΔP and the pressure threshold P.

2. The Rankine cycle system according to claim 1, characterized in that, The Rankine cycle system also includes: The first connecting pipe (70) has a first end connected to the first communication port and a second end connected to the inlet (61). A control valve (80) is installed on the first connecting pipe (70).

3. The Rankine cycle system according to claim 1, characterized in that, The Rankine cycle system also includes: The second connecting pipe (90) has its first end connected to the outlet (62) and its second end connected to the second communication port. A first check valve (100) is provided on the second connecting pipe (90) to allow fluid to flow from the first end to the second end of the second connecting pipe (90).

4. The Rankine cycle system according to claim 1, characterized in that, The Rankine cycle system also includes: The third connecting pipe (110) has its first end connected to the air outlet (21) and its second end connected to the inlet (63). A second one-way valve (120) is provided on the third connecting pipe (110) to allow gas to flow from the first end to the second end of the third connecting pipe (110).

5. The Rankine cycle system according to claim 1, characterized in that, The Rankine cycle system also includes: The pump body (130) is installed on the circulation pipeline (10) and located between the liquid storage tank (20) and the evaporator (30); The first connection port is located between the pump body (130) and the evaporator (30); or, the first connection port is located between the evaporator (30) and the expander (40).

6. The Rankine cycle system according to claim 1, characterized in that, The inlet of the liquid storage tank (20) is located at the top of the liquid storage tank (20), and the vent (21) is located on the side wall of the liquid storage tank (20) and at the top of the side wall.

7. A voltage reduction control method, characterized in that, The buck control method, applicable to any one of claims 1 to 6, comprises: Obtain the pressure value inside the storage tank (20); Determine the relationship between the pressure value and the pressure threshold P. When the pressure value is greater than the pressure threshold P, control the ejector (60) to run; when the pressure value is less than or equal to the pressure threshold P, control the ejector (60) to stop running.

8. The voltage reduction control method according to claim 7, characterized in that, The pressure reduction control method is applicable to the Rankine cycle system of claim 2, wherein the method of controlling the ejector (60) to operate when the pressure value is greater than the pressure threshold P, and controlling the ejector (60) to stop operating when the pressure value is less than or equal to the pressure threshold P, includes: When the pressure value is greater than the pressure threshold P, the control valve (80) is opened. When the pressure value is less than or equal to the pressure threshold P, the control valve (80) is closed.

9. The voltage reduction control method according to claim 8, characterized in that, The voltage reduction control method further includes: Calculate the pressure difference ΔP between the pressure value and the pressure threshold P; The opening degree of the control valve (80) is adjusted according to the ratio between the differential pressure value ΔP and the pressure threshold P; The opening degree of the control valve (80) is positively correlated with the ratio between the differential pressure value ΔP and the pressure threshold P.

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