CN108131860B - Ultralow temperature air source heat pump based on single-machine double-stage compressor - Google Patents

Abstract

The invention proposes an ultra-low temperature air source heat pump based on a single-machine two-stage compressor, which belongs to the technical field of air source heat pumps and includes a shell and tube heat exchanger, a liquid reservoir, a gas-liquid separator, multiple sets of fin heat exchangers, and a single machine. Two-stage compressor, horizontal oil separator, oil cooler, economizer, pressure maintenance valve, four-way reversing valve, one-way valve, multiple solenoid valves, multiple expansion valves and connecting pipelines. This invention uses a single-machine two-stage compressor and an economizer to cool the superheated refrigerant discharged from the first-stage compressor to a nearly saturated gas state, and then enters the second-stage compressor for compression, thereby reducing the power consumption of the compressor under large pressure ratio conditions. Able to provide stable heating in ultra-low temperature environments. The air source heat pump of the present invention is applicable to a wide range of ambient temperatures; it solves the problem of high power consumption and poor heating effect of the air source heat pump in cold areas, and solves the problem that the air source heat pump cannot be used in severely cold areas.

Description

An ultra-low temperature air source heat pump based on a single-machine two-stage compressor

Technical field

The invention belongs to the technical field of air source heat pumps, and particularly relates to an ultra-low temperature air source heat pump based on a single-machine two-stage compressor.

Background technique

At present, air source heat pump products are mainly single-stage compressor systems. The ambient temperature has a greater impact on the unit during heating, and the lowest operating temperature can only reach -15°C. At the same time, due to the limitations of compressor compression ratio, refrigerant characteristics and other factors, when the ambient temperature is very low, it cannot operate effectively for heating, and it cannot even be started.

The principle diagram of an existing air source heat pump based on a single-stage compressor is shown in Figure 1. The air source heat pump includes a (single-stage) compressor 26, a shell-and-tube heat exchanger 17, a liquid reservoir 12, and a gas-liquid separation system. 21, multiple sets of fin heat exchangers (1, 2, 3, three sets are taken as an example for explanation, the specific number of sets is determined according to actual needs), four-way reversing valve 16, one-way valve 11, multiple solenoid valve and multiple expansion valves and connecting pipelines. The first solenoid valve and the first expansion valve are respectively provided at the first port of each group of fin heat exchangers; the connection relationship between each equipment is: the exhaust of the compressor 26 The port is connected to the D port of the four-way reversing valve 16, the E port of the four-way reversing valve 16 is connected to the first port of the shell and tube heat exchanger 17, and the second port of the shell and tube heat exchanger 17 is connected to the one-way valve. The inlet of 11 and the outlet of the one-way valve 11 are connected to the inlet of the liquid reservoir 12. The outlet pipeline of the liquid reservoir 12 is divided into two lines. The first pipeline is divided into three sub-pipes and connected to each group of fins for heat exchange. The inlet of the expansion valve (5, 7, 9) is set at the first port of the device. The outlet pipeline of each expansion valve (5, 7, 9) is divided into two lines and connected to the inlet and outlet of the corresponding solenoid valve (4, 6, 8). The first port of the fin heat exchanger (1, 2, 3) and the outlets of each solenoid valve (4, 6, 8) are merged into a pipeline and connected between the outlet of the one-way valve 11 and the inlet of the liquid reservoir 12 pipe section, the second ports of each fin heat exchanger (1, 2, 3) are merged into one pipeline and connected to the C port of the four-way reversing valve 16, and the S port of the four-way reversing valve 16 is connected to the air The inlet of the liquid separator 21 and the outlet of the gas-liquid separator 21 are connected to the suction port of the compressor 26. The second pipeline of the outlet pipeline of the liquid accumulator 12 passes through the solenoid valve 19 and the expansion valve 18 in sequence and then is connected to the shell. The pipe section between the second port of the tube heat exchanger 17 and the inlet of the one-way valve 11.

Nowadays, various regions are paying more and more attention to environmental protection, and are gradually phasing out high-pollution and high-energy-consuming equipment. Currently, air source heat pumps are being vigorously promoted for heating. There is a large market space in northern my country, but our country is vast. There are obvious differences in temperature. If we want to promote the use of air source heat pumps in Northeast China and other places, ordinary air source heat pumps will not be able to do the job. To ensure comfortable heating temperatures in severe cold areas, the heat pump refrigeration system needs to have a large high and low pressure span, which requires a multi-stage compression system. However, if the multi-stage compression system uses a cascade system, it will lead to higher equipment costs and difficult control. Wait for problems to arise.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the existing technology and propose an ultra-low temperature air source heat pump based on a single-machine two-stage compressor. The air source heat pump can operate in a wide range of ambient temperatures (-30°C ~ 15°C). Stable heating at low temperatures, low equipment costs, and simple unit control.

In order to achieve the above objects, the present invention adopts the following technical solutions:

An ultra-low temperature air source heat pump based on a single-machine two-stage compressor, including a shell and tube heat exchanger (17), a liquid reservoir (12), a gas-liquid separator (21), and multiple sets of fin heat exchangers (1, 2 , 3), four-way reversing valve (16), one-way valve (11), multiple solenoid valves, multiple expansion valves and connecting pipelines; the first ports of each group of fin heat exchangers are respectively equipped with The first solenoid valve and the first expansion valve; the air source heat pump also includes a single-machine two-stage compressor (22), a horizontal oil separator (23), an oil cooler (24), an economizer (14) and a pressure maintenance valve (20); The connection relationship between each device is:

The exhaust port of the single-machine two-stage compressor (22) is connected to the D port of the four-way reversing valve (16) through the horizontal oil separator (23) and the pressure maintenance valve (20). The four-way reversing valve (16) ) is connected to the first port (a) of the shell and tube heat exchanger (17), and the second port (b) of the shell and tube heat exchanger (17) is connected to the liquid reservoir (11) through the one-way valve (11) The inlet of 12) and the outlet of the liquid reservoir (12) are connected to the third port (c) of the economizer (14);

The pipeline at the fourth port (d) of the economizer (14) is divided into two paths, in which the first pipeline is divided into multiple sub-paths and pass through the first expansion valve at the first port of each group of fin heat exchanger and the corresponding fin exchanger respectively. The heat exchanger is connected, and the second ports of each group of fin heat exchangers are merged into a pipeline and connected to the C port of the four-way reversing valve (16). The S port of the four-way reversing valve (16) is separated by gas-liquid The pipe section (21) is connected to the suction port of the single-machine two-stage compressor (22), and the pipe section between the exhaust port of the single-machine two-stage compressor (22) and the air inlet of the horizontal oil separator (23) The fifth solenoid valve (15) is provided in the pipe section between the suction port of the stage compressor (22) and the outlet of the gas-liquid separator (21), and the first solenoid valve (4) is provided at the first port of each group of fin heat exchangers. , 6, 8) The inlet is connected to the pipe section between the first port of the corresponding fin heat exchanger and the outlet of the first expansion valve, and the outlet pipes of each first solenoid valve (4, 6, 8) are merged into one pipe. The second pipeline of the fourth port (d) of the economizer (14) passes through the second solenoid valve (19) in sequence. ) and the second expansion valve (18) are connected to the pipe section between the second port (b) of the shell and tube heat exchanger (17) and the inlet of the one-way valve (11);

The first port (a) pipeline of the economizer (14) is divided into two lines, which are respectively connected to the economizer port of the single-machine two-stage compressor (22) and the balance pipe of the pressure maintenance valve (20). The second port (b) passes through the third expansion valve (13) and the third solenoid valve (10) in sequence and is connected to the pipe section between the outlet of the liquid reservoir (12) and the third port (c) of the economizer (14). ;

The oil outlet pipeline of the horizontal oil separator (23) is divided into two channels, which are respectively connected to the first port (a) of the oil cooler (24) and the inlet of the fourth solenoid valve (25). The fourth solenoid valve (25) ) and the second port (b) pipeline of the oil cooler (24) merge into one pipeline connected to the oil inlet of the single-machine two-stage compressor (22), and the fourth port of the oil cooler (24) (d) Connect the third port (c) of the shell and tube heat exchanger (17); the air conditioning system water flows in from the third port (c) of the oil cooler (24) and flows from the third port (c) of the shell and tube heat exchanger (17). Four ports (d) flow out.

Further, the fifth solenoid valve (15) is opened for a period of time when the single-machine two-stage compressor (22) is started for pressure balance; the third solenoid valve (10) determines the switch according to the low-pass, high-low pressure difference. , open when the pressure difference between high and low pressure is greater than or equal to the set pressure value, and close when the pressure difference between high and low pressure is less than the set pressure value; the fourth solenoid valve (25) judges the switch according to the oil temperature detected in the pipeline. It closes when the oil temperature is higher than the set temperature and opens when the oil temperature is lower than the set temperature;

When the air source heat pump is in heating mode: the solenoid valves (4, 6, 8) at the first port of each group of fin heat exchangers and the second solenoid valve (19) are normally closed; the four-way reversing valve (16) In the powered state, port D is connected to port E, and port C is connected to port S;

When the air source heat pump is in cooling mode: the solenoid valves (4, 6, 8) of the first ports of each group of fin heat exchangers and the second solenoid valve (19) are normally open; the four-way reversing valve ( 16) In the power-off state, port D is connected to port C, and port E is connected to port S.

Characteristics and beneficial results of the present invention:

The invention uses a single-machine two-stage compressor for air source heat pump products, and uses an economizer in the system design to cool the superheated refrigerant discharged from the first-stage compressor to a nearly saturated gas state, and then enters the second-stage compressor for compression. It reduces the power consumption of the compressor under large pressure ratio conditions and can provide stable heating in ultra-low temperature environments.

The air source heat pump of the present invention is applicable to a wide range of ambient temperatures; it solves the problem of high power consumption and poor heating effect of the air source heat pump in cold areas, and solves the problem that the air source heat pump cannot be used in severely cold areas. It provides one more option for central heating in the north, which is economical and environmentally friendly.

Description of the drawings

Figure 1 is a schematic diagram of the principle of an existing air source heat pump based on a single-stage compressor;

Figure 2 is a schematic diagram of the principle of an air source heat pump according to an embodiment of the present invention.

Detailed ways

An ultra-low temperature air source heat pump based on a single-machine two-stage compressor proposed by the present invention is described in detail below with reference to the drawings and examples:

The schematic diagram of the embodiment of the present invention is shown in Figure 2. The air source heat pump includes a shell and tube heat exchanger 17, a liquid reservoir 12, a gas-liquid separator 21, and multiple sets of fin heat exchangers (1, 2, 3, This embodiment is provided with 3 groups of fin heat exchangers), four-way reversing valves 16, one-way valves 11, multiple solenoid valves, multiple expansion valves and connecting pipelines; in each group of fin heat exchangers, One port is respectively provided with a first solenoid valve (4, 6, 8) and a first expansion valve (5, 7, 9); the air source heat pump also includes a single two-stage compressor 22, a horizontal oil separator 23, Oil cooler 24, economizer 14 and pressure maintenance valve 20; the connection relationship between each equipment is:

The exhaust port of the single-machine two-stage compressor 22 is connected to the air inlet of the horizontal oil separator 23, the air outlet of the horizontal oil separator 23 is connected to the inlet of the pressure maintenance valve 20, and the outlet of the pressure maintenance valve 20 is connected to the four Port D of the four-way reversing valve 16, port E of the four-way reversing valve 16 is connected to port a of the shell and tube heat exchanger 17, port b of the shell and tube heat exchanger 17 is connected to the inlet of the one-way valve 11, and the one-way The outlet of the valve 11 is connected to the inlet of the liquid reservoir 12, and the outlet of the liquid reservoir 12 is connected to port c of the economizer 14;

The d-port pipeline of the economizer 14 is divided into two paths, and the first pipeline is divided into multiple sub-paths and is connected to the corresponding fin heat exchanger through the first expansion valve at the first port of each group of fin heat exchangers respectively (this implementation In the example, the first pipeline is divided into three sub-paths and connected to the first port of fin heat exchanger 1, fin heat exchanger 2 and fin heat exchanger 3 respectively through expansion valve 5, expansion valve 7 and expansion valve 9) , the second ports of each group of fin heat exchangers are merged into a pipeline and connected to the C port of the four-way reversing valve 16. The S port of the four-way reversing valve 16 is connected to the inlet of the gas-liquid separator 21. The gas The outlet of the liquid separator 21 is connected to the suction port of the single-machine two-stage compressor 22. The pipe section between the exhaust port of the single-machine two-stage compressor 22 and the air inlet of the horizontal oil separator 23 and the single-machine two-stage compressor 22 The pipe section between the suction port and the outlet of the gas-liquid separator 21 is provided with a solenoid valve 15. The solenoid valve inlet provided at the first port of each group of fin heat exchangers is connected to the first port of the corresponding fin heat exchanger and the first port of the fin heat exchanger. The pipe section between the expansion valve outlets (in this embodiment, the inlets of solenoid valve 4, solenoid valve 6, and solenoid valve 8 are respectively connected to the first port of fin heat exchanger 1 and the outlet of expansion valve 5 and the second port of fin heat exchanger 2. The pipe section between the first port and the outlet of expansion valve 7, the first port of fin heat exchanger 3 and the outlet of expansion valve 9), the outlet pipes of each solenoid valve (4, 6, 8) are merged into one pipe for access The pipe section between the outlet of the one-way valve 11 and the inlet of the reservoir 12; the second pipeline of the d-port pipeline of the economizer 14 is connected to the inlet of the solenoid valve 19, and the outlet of the solenoid valve 19 is connected to the inlet of the expansion valve 18. The outlet of the expansion valve 18 is connected to the pipe section between port b of the shell and tube heat exchanger 17 and the inlet of the one-way valve 11;

The a-port pipeline of the economizer 14 is divided into two lines, which are respectively connected to the economizer port of the single-machine two-stage compressor 22 and the balance pipe of the pressure maintenance valve 20. The b-port of the economizer 14 is connected to the inlet of the expansion valve 13. The expansion valve 13 The outlet of the solenoid valve 10 is connected to the inlet of the solenoid valve 10, and the outlet of the solenoid valve 10 is connected to the pipe section between the outlet of the liquid reservoir 12 and the c port of the economizer 14;

The oil outlet pipeline of the horizontal oil separator 23 is divided into two pipelines, which are respectively connected to the a port of the oil cooler 24 and the inlet of the solenoid valve 25. The outlet of the solenoid valve 25 and the b port pipeline of the oil cooler 24 are merged into one. The root pipeline is connected to the oil inlet of the single-machine two-stage compressor 22, and the d port of the oil cooler 24 is connected to the c port of the shell and tube heat exchanger 17; the air conditioning system water flows in from the c port of the oil cooler 24 and flows from the shell tube Outflow from port d of heat exchanger 17.

This air source heat pump has two working modes: cooling and heating, which are explained as follows:

When the air source heat pump is in the heating mode, solenoid valve 4, solenoid valve 6, solenoid valve 8, and solenoid valve 19 are normally closed; solenoid valve 10 judges the switch based on the system's high and low pressure difference. When the high and low pressure difference is greater than or equal to 10 bar Open when the pressure difference between high and low pressure is less than 10bar; solenoid valve 15 is opened for 10 seconds when the compressor starts for pressure balance; four-way reversing valve 16 is in the powered state, port D is connected to port E, and port C It is connected to the S port; the solenoid valve 25 judges the switch according to the oil temperature detected in the pipeline. When the oil temperature is higher than 70°C, it is closed and when the oil temperature is lower than 50°C, it is opened. The high-temperature and high-pressure refrigerant and lubricating oil mixed gas in the heat pump system enters the air inlet of the horizontal oil separator 23 from the exhaust port of the single-machine two-stage compressor 22. The high-temperature and high-pressure refrigerant in the horizontal oil separator 23 Gas and lubricating oil are separated; high-temperature and high-pressure refrigerant gas enters the inlet of the pressure maintenance valve 20 from the outlet of the horizontal oil separator 23. The function of the pressure maintenance valve 20 is to ensure that the system exhaust reaches the preset pressure before it can be discharged, maintaining compression. The high-low pressure ratio of the machine 22; the high-temperature and high-pressure refrigerant gas enters the D port of the four-way reversing valve 16 from the outlet of the pressure maintenance valve 20. The function of the four-way reversing valve 16 is to switch the refrigerant flow direction to realize the cooling mode and Switching of the heating mode; in the heating mode, the D port and the E port of the four-way reversing valve 16 are connected, and the high-temperature and high-pressure refrigerant gas entering the D port of the four-way reversing valve from the pressure maintenance valve 20 is switched from the four-way reversing valve 16 to the E port. It comes out to port E of the valve and enters port a of the shell and tube heat exchanger 17; the high-temperature and high-pressure refrigerant exchanges heat with the air-conditioning circulating water in the shell-and-tube heat exchanger 17, and releases the heat to the air-conditioning circulating water. At the same time, the high-temperature and high-pressure refrigerant The gas is condensed into high-temperature and high-pressure refrigerant liquid, and then discharged from port b of the shell-and-tube heat exchanger 17 into the one-way valve 11. The one-way valve 11 can only be opened in one direction, with forward flow and no reverse flow; high-temperature and high-pressure refrigeration The refrigerant liquid enters the liquid reservoir 12 through the one-way valve 11. The liquid reservoir is used to store excess refrigerant in the system and ensure that the refrigerant can be effectively sealed before throttling by the expansion valve to avoid flashing refrigerant vapor from affecting the throttling effect. Impact: The high-temperature and high-pressure refrigerant liquid is discharged from the liquid reservoir 12 and enters the c port of the economizer 14 through the main liquid pipeline. Take a branch pipe from the main liquid pipeline before the liquid reservoir 12 and the economizer 14 and pass through the electromagnetic Valve 10 and expansion valve 13, a small part of the high-temperature and high-pressure refrigerant liquid is throttled into a medium-temperature and medium-pressure gas-liquid two-phase mixture through this branch, and enters port b of the economizer 14. The two refrigerants exchange heat. , the high-temperature and high-pressure refrigerant liquid in the main liquid pipeline passes through the economizer 14 and is cooled into a high-pressure subcooled liquid. The throttled medium-temperature and medium-pressure refrigerant in the branch circuit passes through the economizer 14 and evaporates into a medium-pressure saturated gaseous state. The refrigerant flows out from port a of the economizer 14 and enters the medium-pressure cavity of the single-machine two-stage compressor 22. It mixes with the medium-pressure superheated refrigerant exhaust of the first-stage compressor and cools the exhaust gas temperature after the first-stage compression. After being sent to the secondary compressor for compression, the high-pressure refrigerant liquid that has been supercooled by the economizer 14 is discharged from port d of the economizer 14, and is divided into three branches and passes through the expansion valve 5, expansion valve 7, and expansion valve 9) respectively. The gas-liquid two-phase mixture flows into a low-temperature and low-pressure gas-liquid mixture, and then enters the first, second, and third fin heat exchangers (1, 2, and 3) respectively to exchange heat with the outside air. By absorbing the heat in the air, the low-temperature and low-pressure mixture The refrigerant evaporates into low-pressure superheated gas, and then merges into a pipeline to enter the C port of the four-way reversing valve 16; at this time, the C port and S port of the four-way reversing valve 16 are connected; the low-pressure superheated refrigerant gas It is discharged from the S port of the four-way reversing valve 16 into the gas-liquid separator 21. The function of the gas-liquid separator is to separate the refrigerant liquid that has not completely evaporated and prevent the refrigerant liquid from entering the compressor and causing wet compression. The refrigerant liquid is separated in 21, and the low-pressure refrigerant gas is discharged and then sucked into the suction port of the single-machine two-stage compressor 22 to complete the refrigerant cycle. The flow process of the lubricating oil is that after being separated by the horizontal oil separator 23, it flows out from the oil outlet of the horizontal oil separator 23. In order to prevent the lubricating oil temperature from being too high, the system is equipped with an oil cooler 24 and a horizontal oil separator. The lubricating oil discharged from the oil outlet 23 enters port a of the oil cooler 24. The lubricating oil exchanges heat with the air conditioning circulating water in the oil cooler. After being cooled, the lubricating oil is discharged from port b of the oil cooler 24 and enters the compressor oil inlet. In the system design, when the lubricating oil temperature is not high, an oil circuit bypass is set to avoid unnecessary oil cooling. The solenoid valve 25 plays the role of oil circuit bypass. The above is the flow process of refrigerant and lubricating oil in heating mode.

When the air source heat pump is in cooling mode, solenoid valve 4, solenoid valve 6, solenoid valve 8, and solenoid valve 19 are normally open; solenoid valve 10 determines the switch based on the low-pass high-low pressure difference. When the high-low pressure difference is greater than or equal to 10 bar Open when the pressure difference between high and low pressure is less than 10bar; solenoid valve 15 is opened for 10 seconds when the compressor starts for pressure balance; four-way reversing valve 16 is in a power-off state, and port D is connected to port C, and port E It is connected to the S port; the solenoid valve 25 judges the switch according to the oil temperature detected in the pipeline. When the oil temperature is higher than 70°C, it is closed and when the oil temperature is lower than 50°C, it is opened. The high-temperature and high-pressure refrigerant and lubricating oil mixed gas in the heat pump system enters the air inlet of the horizontal oil separator 23 from the exhaust port of the single-machine two-stage compressor 22. The high-temperature and high-pressure refrigerant gas in the horizontal oil separator 23 Separate from the lubricating oil; the high-temperature and high-pressure refrigerant gas enters the inlet of the pressure maintenance valve 20 from the outlet of the horizontal oil separator 23. The function of the pressure maintenance valve 20 is to ensure that the system exhaust reaches the preset pressure before it can be discharged, maintaining the compressor The high-low pressure ratio; the high-temperature and high-pressure refrigerant gas enters the D port of the four-way reversing valve 16 from the outlet of the pressure maintenance valve 20. The function of the four-way reversing valve 16 is to switch the refrigerant flow direction to achieve cooling mode and heating. Mode switching; in the cooling mode, port D and port C of the four-way reversing valve 16 are connected, and the high-temperature and high-pressure refrigerant gas entering port D of the four-way reversing valve from the pressure maintenance valve 20 passes through the four-way reversing valve C. The outlet is divided into three branches and enters the first, second, and third fin heat exchangers (1, 2, 3) respectively, exchanging heat with the outside air, releasing the heat into the air, and the high-temperature and high-pressure refrigerant condenses into The high-pressure refrigerant liquid passes through solenoid valve 4, solenoid valve 6, and solenoid valve 8) respectively, and then merges into a pipeline and enters the liquid reservoir 12. The liquid reservoir is used to store excess refrigerant in the system and ensure that the refrigerant remains in the system. The expansion valve can effectively seal the liquid before throttling to avoid the impact of flash refrigerant vapor on the throttling effect; the high-temperature and high-pressure refrigerant liquid is discharged from the liquid reservoir 12 and enters the c port of the economizer 14 through the main liquid pipeline. A branch pipe is taken from the main liquid pipeline before the accumulator 12 and the economizer 14 and passes through the solenoid valve 10 and the expansion valve 13. A small part of the high-temperature and high-pressure refrigerant liquid is throttled into medium-temperature and medium-pressure gas through this branch. The liquid two-phase mixture enters port b of the economizer 14. The two refrigerants exchange heat. The high-temperature and high-pressure refrigerant liquid in the main liquid pipeline passes through the economizer 14 and is cooled into a high-pressure supercooled liquid. The throttled medium-temperature and medium-pressure refrigerant passes through the economizer 14 and evaporates into a medium-pressure saturated gaseous refrigerant. It flows out from port a of the economizer 14 and enters the medium-pressure chamber of the single-machine two-stage compressor 22 and the medium pressure chamber of the first-stage compressor. The superheated refrigerant exhaust is mixed, and the exhaust temperature after the first-stage compression is cooled. After mixing, it is sent to the second-stage compressor for compression. The high-pressure refrigerant liquid after being supercooled by the economizer 14 is discharged from the d port of the economizer 14 , through the solenoid valve 19 and the expansion valve 18, the two-phase refrigerant mixture that is throttled into low temperature and low pressure enters port b of the shell and tube heat exchanger 17, and exchanges heat with the air conditioning circulating water. By absorbing the heat in the air conditioning circulating water, the low temperature and low pressure The refrigerant evaporates into low-pressure superheated gas and enters the E port of the four-way reversing valve 16; at this time, the E port and S port of the four-way reversing valve 16 are connected; the low-pressure superheated refrigerant gas flows through the four-way reversing valve 16. The S port is discharged into the gas-liquid separator 21. The function of the gas-liquid separator is to separate the refrigerant liquid that has not completely evaporated, to prevent the refrigerant liquid from entering the compressor and causing wet compression, and to separate the refrigerant liquid in the gas-liquid separator 21. The discharged low-pressure refrigerant gas is then sucked into the suction port of the single-machine two-stage compressor 22 to complete the refrigerant cycle. The flow process of lubricating oil is that after being separated by the horizontal oil separator 23, it flows out from the oil outlet of the horizontal oil separator 23. In order to prevent the lubricating oil temperature from being too high, the system is equipped with an oil cooler 24 and a horizontal oil separator. The lubricating oil discharged from the oil outlet 23 enters port a of the oil cooler 24. The lubricating oil exchanges heat with the air conditioning circulating water in the oil cooler. After being cooled, the lubricating oil is discharged from port b of the oil cooler 24 and enters the compressor oil inlet. In the system design, when the lubricating oil temperature is not high, an oil circuit bypass is set to avoid unnecessary oil cooling. The solenoid valve 25 plays the role of oil circuit bypass. The above is the flow process of refrigerant and lubricating oil in refrigeration mode.

The air source heat pump of the present invention can realize single-compressor two-stage compression, has a large system high-low pressure ratio, can adapt to low-temperature environments, can stably heat in a low-temperature environment of -30°C, and has obvious economic benefits.

The specific implementation of the main components of the present invention is described as follows:

The main components of the invention are a single-machine two-stage compressor, a horizontal oil separator, a four-way reversing valve, a shell and tube heat exchanger, a gas-liquid separator, a liquid reservoir, an economizer, a fin heat exchanger, and an oil cooler. , solenoid valve, expansion valve, pressure maintenance valve, and one-way valve are all commercially available mature products.

Example:

1. For a single-machine two-stage compressor, the compressor displacement is determined based on the mass flow rate of the refrigeration system and the unit load to determine the compressor model. In this embodiment, the compressor selected is the Fusheng brand SRT413 model single-machine two-stage compressor;

2. For horizontal oil separators, the model is selected based on the compressor displacement and the average flow rate in the horizontal oil separator;

3. The four-way reversing valve is selected according to the cooling capacity of the refrigeration system;

4. The shell and tube heat exchanger is calculated and selected based on the heating capacity of the heat pump host, the physical properties of the heat exchange medium on both sides of the heat exchanger, and the heat transfer properties of the heat exchange material;

5. Gas-liquid separator, choose the appropriate model according to the refrigerant filling amount and cooling capacity of the system refrigeration system;

6. Liquid receiver, select the appropriate model according to the refrigerant filling amount of the system refrigeration system and the size of the system pipeline;

7. The economizer is calculated and selected based on the medium-pressure heat transfer amount of the refrigeration system and the temperatures on both sides of the heat exchanger;

8. The fin heat exchanger is calculated and selected based on the cooling capacity of the refrigeration system, the physical properties of the heat exchange medium on both sides of the heat exchanger, the heat exchange material and fin material, and the fin spacing;

9. Oil cooler, calculation and selection based on oil volume, heat exchange temperature difference, water side temperature difference, and heat transfer properties of the heat exchange tube material;

10. Solenoid valves, expansion valves, and one-way valves are selected according to the system load and pipeline structure;

11. The pressure maintenance valve is a compressor accessory and is matched by the manufacturer;

12. Other pipeline valves are determined according to the pipeline and needs.

The above descriptions are only preferred embodiments of the present invention and do not limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the present invention. within the scope of protection.

Claims (2)

1. An ultra-low temperature air source heat pump based on a single-machine two-stage compressor, including a shell and tube heat exchanger (17), a liquid reservoir (12), a gas-liquid separator (21), and multiple sets of fin heat exchangers (1 , 2, 3), four-way reversing valve (16), one-way valve (11), multiple solenoid valves, multiple expansion valves and connecting pipelines; at the first port of each group of fin heat exchangers, It is provided with a first solenoid valve and a first expansion valve; it is characterized in that the air source heat pump also includes a single-machine two-stage compressor (22), a horizontal oil separator (23), an oil cooler (24), an economizer ( 14) and pressure maintenance valve (20); the connection relationship between each equipment is: The exhaust port of the single-machine two-stage compressor (22) is connected to the D port of the four-way reversing valve (16) through the horizontal oil separator (23) and the pressure maintenance valve (20). The four-way reversing valve (16) ) is connected to the first port (a) of the shell and tube heat exchanger (17), and the second port (b) of the shell and tube heat exchanger (17) is connected to the liquid reservoir (11) through the one-way valve (11) The inlet of 12) and the outlet of the liquid reservoir (12) are connected to the third port (c) of the economizer (14); The pipeline at the fourth port (d) of the economizer (14) is divided into two paths, and the first pipeline is divided into multiple sub-paths that pass through the first expansion valve at the first port of each group of fin heat exchangers and the corresponding fin exchanger respectively. The heat exchanger is connected, and the second ports of each group of fin heat exchangers are merged into a pipeline and connected to the C port of the four-way reversing valve (16). The S port of the four-way reversing valve (16) is separated by gas and liquid. The pipe section (21) is connected to the suction port of the single-machine two-stage compressor (22), and the pipe section between the exhaust port of the single-machine two-stage compressor (22) and the air inlet of the horizontal oil separator (23) The fifth solenoid valve (15) is provided in the pipe section between the suction port of the stage compressor (22) and the outlet of the gas-liquid separator (21), and the first solenoid valve (4) is provided at the first port of each group of fin heat exchangers. , 6, 8) The inlet is connected to the pipe section between the first port of the corresponding fin heat exchanger and the outlet of the first expansion valve, and the outlet pipes of each first solenoid valve (4, 6, 8) are merged into one pipe The second pipeline of the fourth port (d) of the economizer (14) passes through the second solenoid valve (19) in sequence. ) and the second expansion valve (18) are connected to the pipe section between the second port (b) of the shell and tube heat exchanger (17) and the inlet of the one-way valve (11); The first port (a) pipeline of the economizer (14) is divided into two lines, which are respectively connected to the economizer port of the single-machine two-stage compressor (22) and the balance pipe of the pressure maintenance valve (20). The second port (b) passes through the third expansion valve (13) and the third solenoid valve (10) in turn and is connected to the pipe section between the outlet of the liquid reservoir (12) and the third port (c) of the economizer (14). ; The oil outlet pipeline of the horizontal oil separator (23) is divided into two channels, which are respectively connected to the first port (a) of the oil cooler (24) and the inlet of the fourth solenoid valve (25). The fourth solenoid valve (25) ) and the second port (b) pipeline of the oil cooler (24) merge into one pipeline connected to the oil inlet of the single-machine two-stage compressor (22) and the fourth port of the oil cooler (24) (d) Connect the third port (c) of the shell and tube heat exchanger (17); the air conditioning system water flows in from the third port (c) of the oil cooler (24) and flows from the third port (c) of the shell and tube heat exchanger (17). Four port (d) outflow. 2. The air source heat pump according to claim 1, characterized in that the fifth solenoid valve (15) is opened for a period of time when the single-machine two-stage compressor (22) is started for pressure balance; the third The solenoid valve (10) judges the switch based on the low-pass high-low pressure difference. It opens when the high-low pressure difference is greater than or equal to the set pressure value, and closes when the high-low pressure difference is less than the set pressure value; the fourth solenoid valve (10) 25) The switch is judged based on the oil temperature detected in the pipeline. When the oil temperature is higher than the set temperature, it is closed and when the oil temperature is lower than the set temperature, it is opened; When the air source heat pump is in heating mode: the first solenoid valves (4, 6, 8) and the second solenoid valve (19) at the first port of each group of fin heat exchangers are normally closed; the four-way exchanger The directional valve (16) is in the powered state, port D is connected to port E, and port C is connected to port S; When the air source heat pump is in cooling mode: the first solenoid valves (4, 6, 8) and the second solenoid valve (19) at the first port of each group of fin heat exchangers are normally open; the four-way reversal Valve (16) is in a power-off state, port D is connected to port C, and port E is connected to port S.