Mechanical refrigeration system

Abstract

The mechanical refrigerating system comprises a compressor, a condenser, a main throttling device and an evaporator which are sequentially communicated, the compressor comprises a low-stage compression part and a high-stage compression part which are connected in series through a grading channel in the fluid flowing direction, the compressor is provided with a cooling loop, and the mechanical refrigerating system further comprises an auxiliary throttling device. An inlet of the auxiliary throttling device is communicated to a channel between the condenser and the main throttling device; and an outlet of the auxiliary throttling device directly or indirectly supplies a refrigerant to the cooling loop and the grading channel. By means of the auxiliary throttling device, cooling of the compressor can be achieved, meanwhile, the suction pressure of the high-grade compression part can be guaranteed, and the compression work is improved; and compared with two throttling devices, the energy consumption can be better reduced. In conclusion, the mechanical refrigeration system can effectively solve the problem that the energy consumption reduction effect is poor.

Description

Technical Field

[0001] The utility model relates to the technical field of temperature control, and more specifically to a mechanical refrigeration system. Background Art

[0002] The existing centrifugal compressor refrigeration system, when having the function of replenishing air and increasing enthalpy, usually has two circuits at the outlet of the condenser, one of which is the main circuit, and the transfer and exchange of the cold and heat of the load is mainly realized by the main circuit, and the other circuit is the branch circuit, which mainly has two functions: on the one hand, it provides subcooling for the condensing end of the main circuit, and on the other hand, it supplements the cold capacity for the suction end of the higher level of the compressor, resulting in less work per unit volume of compression; and the branch circuit usually has an electronic expansion valve, which throttles and cools down the condenser of the main circuit through the electronic expansion valve, so that the condenser of the main circuit is supercooled, and the refrigeration capacity is increased. If for a two-stage compressor, adding air replenishment between the first and second stages will make the originally higher pressure gas of the second stage suction gas combined with the medium pressure gas of the air replenishment, thereby reducing the suction pressure, reducing the compression work, and improving the overall energy efficiency;

[0003] After long-term practice, the inventor of the utility model discovered that during the process of replenishing air and increasing enthalpy, the added electronic expansion valve control brings about power loss in the system, and the greater the throttling of the electronic expansion valve, the greater the loss of its pressure energy in converting into kinetic energy. The centrifugal compressor in the prior art has a high power density due to the high speed and generates a large amount of heat, and also needs to be cooled, that is, a cooling circuit needs to be set up. The above-mentioned branch for replenishing air in the higher-level compression part and the cooling circuit on the centrifugal compressor respectively use electronic expansion valves to achieve throttling to obtain low-temperature fluid. The above-mentioned method does not form an effective regulation within the system and will cause an increase in actual energy consumption.

[0004] In the process of realizing the utility model, the inventor discovered that there are at least the following problems in the prior art: How to effectively solve the problem of poor energy consumption reduction effect is a problem that technical personnel in this field urgently need to solve. Utility Model Content

[0005] In view of this, an object of the present invention is to provide a mechanical refrigeration system, which can effectively solve the problem of poor energy consumption reduction effect.

[0006] In order to achieve the above object, the utility model provides the following technical solutions:

[0007] A mechanical refrigeration system includes a compressor, a condenser, a main throttling device and an evaporator connected in sequence, the compressor includes a low-stage compression part and a high-stage compression part connected in series through a progressive channel along the fluid flow direction, the compressor has a cooling circuit, and also includes a secondary throttling device, the inlet of the secondary throttling device is connected to the channel between the condenser and the main throttling device; the outlet of the secondary throttling device directly or indirectly supplies refrigerant to the cooling circuit and the progressive channel.

[0008] In the above-mentioned mechanical refrigeration system, the cooling circuit and the progressive channel share a sub-throttling device, which can reduce the number of sub-throttling devices. In the process of replenishing air and increasing enthalpy, adding electronic expansion valve control will cause power loss in the system, and the greater the throttling of the electronic expansion valve, the greater the loss of its pressure energy in converting into kinetic energy. A sub-throttling device can not only achieve the cooling of the compressor, but also ensure the suction pressure of the high-stage compression part, thereby improving the compression work; and compared with two throttling devices, it can better reduce energy consumption. In summary, the mechanical refrigeration system can effectively solve the problem of poor energy consumption reduction effect.

[0009] In some technical solutions, an economizer is also included, wherein one channel of the economizer is connected between the condenser and the main throttling device; another channel of the economizer is connected between the auxiliary throttling device and the progressive channel; and the inlet of the auxiliary throttling device is connected to the channel between the condenser and the economizer.

[0010] In some technical solutions, the outlet of the secondary throttling device is connected to the inlet of the cooling circuit and the progressive channel respectively through a three-way structure.

[0011] In some technical solutions, the outlet of the cooling circuit is connected to the channel between the evaporator and the compressor or to the channel between the main throttling device and the evaporator.

[0012] In some technical solutions, a flow control valve is provided between the three-way structure and the progressive channel.

[0013] In some technical schemes, a sensor is further included for obtaining the degree of subcooling at the condenser outlet. The flow control valve is opened by a first opening value when the sensor detection value is less than the target value, and is opened by a second opening value when the sensor detection value is greater than the target value. The second opening value is greater than the first opening value.

[0014] In some technical solutions, the outlet of the secondary throttling device is communicated with the inlet of the cooling circuit, and the outlet of the cooling circuit is communicated with the progressive passage.

[0015] In some technical solutions, a booster pump is provided between the outlet of the cooling circuit and the progressive passage.

[0016] In some technical solutions, the main throttling device and the auxiliary throttling device are both electronic expansion valves.

[0017] In some technical solutions, the auxiliary throttling device is a throttle valve with controllable opening, and the opening can be adjusted according to the temperature of the motor in the compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A schematic diagram of the structure of a mechanical refrigeration system provided by an embodiment of the utility model;

[0020] Figure 2 A schematic structural diagram of another mechanical refrigeration system provided in an embodiment of the utility model.

[0021] The following are marked in the accompanying drawings:

[0022] Compressor 1, condenser 2, main throttling device 3, evaporator 4, progressive passage 5, cooling circuit 6, auxiliary throttling device 7, economizer 8, flow control valve 9, low-stage compression section 11, and high-stage compression section 12. DETAILED DESCRIPTION

[0023] The embodiment of the utility model discloses a mechanical refrigeration system, which can effectively solve the problem of poor energy consumption reduction effect.

[0024] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] See also Figure 1-Figure 2 , Figure 1 A schematic diagram of the structure of a mechanical refrigeration system provided by an embodiment of the utility model; Figure 2 A schematic structural diagram of another mechanical refrigeration system provided in an embodiment of the utility model.

[0026] In some embodiments, this embodiment provides a mechanical refrigeration system, which can also be called an air-conditioning system, mainly including a compressor 1, a condenser 2, a main throttling device 3 and an evaporator 4 connected in sequence, that is, the outlet of the evaporator 4 also needs to be connected to the inlet of the compressor 1 to form a circulation system, called the main path. Heat is released at the condenser 2 and heat is absorbed at the evaporator 4 to achieve temperature control. The compressor 1 compresses the inhaled gas to form high-temperature and high-pressure superheated steam, which releases heat to the outside after flowing into the condenser 2 to form a medium-temperature and high-pressure liquid. Through the throttling process of the main throttling device 3, the liquid becomes a medium-temperature and low-pressure liquid. When it flows through the evaporator from the outlet of the main throttling device 3, the gas pressure drops rapidly and the volume expands rapidly, which absorbs a large amount of heat to achieve temperature transfer.

[0027] The compressor 1 includes at least two compression parts connected in series along the fluid flow direction through the progressive channel 5, which can be a two-stage compression part, a three-stage compression part, or other-stage compression parts. In order to facilitate the description of the present application scheme, the two-stage compression parts are respectively a low-stage compression part 11 and a high-stage compression part 12. The gas compressed by the low-stage compression part 11 flows into the high-stage compression part 12 through the progressive channel 5, and is further compressed by the high-stage compression part 12 to obtain a higher-pressure gas. Of course, in addition to the above-mentioned low-stage compression part 11 and high-stage compression part 12, more stages of compression parts can be set, and even other stages of compression parts can be set between the low-stage compression part 11 and the high-stage compression part 12. At this time, the progressive channel 5 is not directly connected to at least the low-stage compression part 11 and the high-stage compression part 12, but is indirectly connected through other stages of compression parts.

[0028] The compressor 1 is provided with a cooling circuit 6, which is mainly used to cool the power components on the compressor 1. Generally, the power components on the compressor 1 are the motor parts, and the cooling circuit 6 is used to cool the motor parts. The specific arrangement of the cooling circuit 6 on the compressor 1 can be arranged according to the cooling needs of the compressor 1. An inlet and an outlet are formed on the cooling circuit 6. The main part of the cooling circuit 6 can be wound around the power components, or the cavity where the power components are located can be used to form the above-mentioned cooling circuit 6. The specific arrangement can be made according to the needs.

[0029] In addition to the above-mentioned main circuit, a bypass, also known as a branch circuit, is generally required. The bypass has two main purposes: one is to replenish air for the progressive channel 5 to ensure the compression effect of the high-stage compression part 12, and the other is to supply the cooling circuit 6 of the compressor 1 to provide refrigerant to the cooling circuit 6 of the compressor 1.

[0030] In some embodiments, a secondary throttling device 7 is provided, and the inlet of the secondary throttling device 7 is connected to the channel between the condenser 2 and the main throttling device 3, that is, a bypass is opened between the condenser 2 and the main throttling device 3. The outlet of the secondary throttling device 7 directly or indirectly supplies refrigerant to the cooling circuit 6 and the progressive channel 5. There are three main ways to supply refrigerant: one is to supply refrigerant to the cooling circuit 6 and the progressive channel 5 respectively through a three-way structure, at which time the fluid in the cooling circuit 6 will be guided back to the main path from the outlet; the second is to supply refrigerant to the cooling circuit 6, and the refrigerant flowing out of the outlet of the cooling circuit 6 is guided to the progressive channel 5, so as to realize indirect supply to the progressive channel 5; the third is to supply refrigerant to the cooling circuit 6, and the outlet of the cooling circuit 6 is guided to the main path and the progressive channel 5 respectively through a three-way structure, wherein the guide to the main path is connected to the channel between the evaporator 4 and the compressor 1.

[0031] In the above-mentioned mechanical refrigeration system, the cooling circuit 6 and the progressive channel 5 share a sub-throttling device 7, which can reduce the number of sub-throttling devices 7. In the process of replenishing air and increasing enthalpy, adding electronic expansion valve control will cause power loss in the system, and the greater the throttling of the electronic expansion valve, the greater the loss of its pressure energy in converting into kinetic energy. A sub-throttling device 7 can not only achieve the cooling of the compressor 1, but also ensure the suction pressure of the high-stage compression part 12, thereby improving the compression work; and compared with two throttling devices, it can better reduce energy consumption. In summary, the mechanical refrigeration system can effectively solve the problem of poor energy consumption reduction effect.

[0032] In some embodiments, an economizer 8 is generally provided on the main circuit, wherein the economizer 8 is provided between the condenser 2 and the main throttling device 3, so as to cool down the fluid flowing into the main throttling device 3. Specifically, the economizer 8 mainly includes two channels that can exchange heat with each other, wherein one channel is connected to the main circuit, and the other channel introduces a low-temperature refrigerant to absorb heat from the fluid in the main circuit, so as to cool down the fluid in the main circuit.

[0033] Specifically, one channel of the economizer 8 is connected between the condenser 2 and the main throttling device 3, and the other channel of the economizer 8 is connected between the auxiliary throttling device 7 and the progressive channel 5. The low-temperature refrigerant flowing out of the auxiliary throttling device 7 can first pass through the economizer 8 to cool the main fluid, and then flow into the progressive channel 5 after absorbing heat, which can not only reduce the channel usage, but also better replenish the progressive channel 5 with air.

[0034] It should be noted that, at this time, the inlet of the auxiliary throttling device 7 can be connected to the channel between the condenser 2 and the economizer 8 to reduce the working pressure of the economizer 8 while meeting the use requirements. Of course, the inlet of the auxiliary throttling device 7 can also be connected to the channel between the economizer 8 and the main throttling device 3.

[0035] In some embodiments, the outlet of the auxiliary throttling device 7 can be connected to the inlet of the cooling circuit 6 and the progressive channel 5 respectively through a three-way structure, so that the auxiliary throttling device 7 can be split at the three-way structure to supply to the cooling circuit 6 and the progressive channel 5 respectively, avoiding mutual influence on power.

[0036] When the economizer 8 is provided, the corresponding channel of the economizer 8 can be connected between the three-way structure and the progressive channel 5. In this case, the low-temperature fluid flowing through the economizer 8 can be better utilized.

[0037] It should be noted that the three-way structure can further adopt a three-way valve, and the fluid flow direction of the auxiliary throttling device 7 can be controlled by the three-way valve.

[0038] Of course, a flow control valve 9 may be provided between the three-way structure and the cooling circuit 6, and / or a flow control valve 9 may be provided between the three-way structure and the progressive channel 5. If a flow control valve 9 is provided between the three-way structure and the cooling circuit 6, or a flow control valve 9 is provided between the three-way structure and the progressive channel 5, the flow of the corresponding channel can be controlled by adjusting the flow control valve 9, thereby changing the ratio of the fluid entering the cooling circuit 6 and the progressive channel 5. If a flow control valve 9 is provided between the three-way structure and the cooling circuit 6, and a flow control valve 9 is provided between the three-way structure and the progressive channel 5, not only the ratio of the fluid entering the cooling circuit 6 and the progressive channel 5 can be controlled, but also the fluid pressure can be controlled.

[0039] Considering that the progressive channel 5 needs to control the fluid velocity more, a flow control valve 9 is provided between the three-way structure and the progressive channel 5. Even if the economizer 8 is provided, the flow control valve 9 can be directly connected to the progressive channel 5 without passing through the economizer 8.

[0040] In some embodiments, the outlet of the cooling circuit 6 can be connected to the inlet of the compressor 1. However, considering that the fluid flowing out of the outlet of the cooling circuit 6 may contain liquid when the compressor 1 is started for a short time or in other situations, the outlet of the cooling circuit 6 can be connected to the channel between the evaporator 4 and the compressor 1 and be arranged close to the evaporator 4.

[0041] Here, the outlet of the cooling circuit 6 is preferably connected to the channel between the evaporator 4 and the main throttling device 3 to better utilize the evaporator 4 and fully avoid liquid from entering the compressor 1 and affecting the service life of the compressor 1.

[0042] In some embodiments, a sensor for obtaining the degree of subcooling at the outlet of the condenser 2 is also included, wherein the flow control valve 9 can adjust the opening accordingly according to the detection value of the sensor to achieve linkage control between each other. For specific information on how to control the flow valve according to the set rules based on the temperature sensor, reference can be made to the prior art, and the set rules are obtained by obtaining a corresponding data table between the detection value and the opening according to methods such as experiments.

[0043] Specifically, the flow control valve 9 can be made to reduce the opening to a first value when the sensor detection value is less than the target value, and increase the opening to a second value when the sensor detection value is greater than the target value, and the second opening value is greater than the first opening value.

[0044] In some embodiments, the outlet of the sub-throttling device 7 can be connected to the inlet of the above-mentioned cooling circuit 6, and the outlet of the above-mentioned cooling circuit 6 can be connected to the progressive channel 5 to achieve series connection. At this time, the sub-throttling device 7 directly supplies fluid to the cooling circuit 6, and indirectly supplies fluid to the progressive channel 5.

[0045] Further, it is preferred that a booster pump is provided between the cooling circuit 6 and the progressive channel 5, and a fluid pressure detection device for detecting the pressure on the outlet side of the booster pump is provided, and the booster pump is controlled to start when the detection value of the fluid pressure detection device is lower than a preset value, and at this time, the opening of the secondary throttling device 7 can also be adjusted accordingly. It should be noted that the outlet side of the booster pump is, for example, on the channel between the outlet of the booster pump and the progressive channel 5, or on the progressive channel 5.

[0046] In some embodiments, both the main throttling device 3 and the auxiliary throttling device 7 can be electronic expansion valves. Specifically, other throttling devices can also be used, which will not be described in detail here.

[0047] In some embodiments, the secondary throttling device 7 can be a throttle valve with controllable opening, and the opening can be adjusted according to the motor temperature in the compressor 1. When the motor temperature rises and exceeds the set temperature value, the opening of the secondary throttling device 7 is controlled to increase.

[0048] In some examples, in a mechanical refrigeration system, the existing air-supply and heat-increasing electronic expansion valve is eliminated and used in conjunction with the existing motor cooling electronic expansion valve. An electric ball valve can be added to adjust the cooling bypass flow according to temperature changes.

[0049] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0050] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A mechanical refrigeration system, comprising a compressor, a condenser, a main throttling device and an evaporator connected in sequence, characterized in that: The compressor includes a low-stage compression part and a high-stage compression part connected in series through a progressive channel along the fluid flow direction. The compressor is provided with a cooling circuit. The mechanical refrigeration system also includes a secondary throttling device, the inlet of which is connected to the channel between the condenser and the main throttling device; the outlet of the secondary throttling device directly or indirectly supplies refrigerant to the cooling circuit and the progressive channel.

2. The mechanical refrigeration system according to claim 1, characterized in that: It also includes an economizer, one channel of which is connected between the condenser and the main throttling device; another channel of the economizer is connected between the auxiliary throttling device and the progressive channel; the inlet of the auxiliary throttling device is connected to the channel between the condenser and the economizer.

3. The mechanical refrigeration system according to claim 1, characterized in that: The outlet of the secondary throttling device is respectively connected with the inlet of the cooling circuit and the progressive channel through a three-way structure.

4. The mechanical refrigeration system according to claim 3, characterized in that: The outlet of the cooling circuit is connected to the passage between the evaporator and the compressor or to the passage between the main throttling device and the evaporator.

5. The mechanical refrigeration system according to claim 3, characterized in that: A flow control valve is arranged on the channel between the three-way structure and the progressive channel.

6. The mechanical refrigeration system according to claim 5, characterized in that: It also includes a sensor for obtaining the degree of subcooling at the condenser outlet. The flow control valve reduces its opening to a first opening value when the sensor detection value is less than the target value, and increases its opening to a second opening value when the sensor detection value is greater than the target value. The second opening value is greater than the first opening value.

7. The mechanical refrigeration system according to claim 1, characterized in that: The outlet of the secondary throttling device is communicated with the inlet of the cooling circuit, and the outlet of the cooling circuit is communicated with the progressive passage.

8. The mechanical refrigeration system according to claim 7, characterized in that: A booster pump is provided between the outlet of the cooling circuit and the progressive passage.

9. The mechanical refrigeration system according to claim 1, characterized in that: The main throttling device and the auxiliary throttling device are both electronic expansion valves.

10. The mechanical refrigeration system according to claim 9, characterized in that: The auxiliary throttling device is a throttle valve with controllable opening, and the opening can be adjusted according to the temperature of the motor in the compressor.

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