CN108489130A - A kind of screw single machine three stage compression heat pump heating system and control method - Google Patents

Abstract

The invention discloses a screw-type single-unit three-stage compression heat pump heating system and a control method, which is characterized in that it comprises a single-unit three-stage screw compressor, and the single-unit three-stage screw compressor is provided with a refrigerant inlet, a refrigerant outlet, a first The air supply port, the second air supply port and the oil return port, the refrigerant inlet are connected to the gas-liquid separator, and the refrigerant outlet is connected to the oil separator; the first air supply port is connected to the second economizer, and the second air supply port is connected to the first The economizer is now connected, the oil outlet of the oil separator is connected to the oil cooler, and then connected to the oil filter, solenoid valve and oil flow switch in sequence, and finally connected to the oil return port of the single-unit three-stage screw compressor. Solve the problems of existing air source heat pumps that the compression ratio exceeds the limit, the outlet water temperature is low, and the operating environment is narrow. This technical solution can be applied in all heating areas in my country, and will directly replace traditional coal-fired boilers. It is convenient and economical to install and transform. , Energy saving and environmental protection, it is a better heating technology solution.

Description

A screw-type single-unit three-stage compression heat pump heating system and control method

technical field

The invention relates to the technical field of air source heat pumps, in particular to a screw-type single-unit three-stage compression heat pump heating system and a control method.

Background technique

Among the existing heating methods in northern my country, radiator heating is the mainstream method. In recent years, under the "coal to electricity" policy, air source heat pumps combined with radiator heating have been widely used. Air source heat pumps replace coal-fired boilers for my country's environment. The improvement has played a great role, but the existing air source heat pump with radiator heating has the following defects:

1. The outlet water temperature is low, the highest is only 60°C, while the outlet water temperature of traditional coal-fired boilers is above 80°C. Due to the low water temperature, the air source heat pump cannot match the traditional cast iron radiator, so it can only be replaced with an expensive new radiator Appliances, and the comfort is poor, such as the use of floor heating, the transformation workload is relatively large, and the cost is relatively high.

2. It can only be used in areas above -25°C, and cannot be used in cold areas such as northeast and northwest, which limits the promotion of air source heat pumps.

3. Although the single-unit two-stage compressed air source heat pump or cascade air source heat pump that has been initially applied in recent years has increased the temperature of the outlet water and expanded the application range to a certain extent, because the compression ratio exceeds the limit, there are also cases in extremely cold ambient temperatures. The output water temperature is low, the stability and reliability of the mixed refrigerant is poor, and the energy efficiency of the unit is low.

4. The air source heat pump starts and stops frequently during heating, the life of the unit is short, and the stability and comfort of the heating system are poor.

Contents of the invention

The technical problem to be solved by the present invention is how to effectively match the air source heat pump with the existing traditional radiator to realize the use of air source heat pump heating in ultra-low temperature environment and improve the outlet water temperature.

In order to solve the above technical problems, the present invention designs a screw-type single-unit three-stage compression heat pump heating system, which is characterized in that it includes a single-unit three-stage screw compressor, and the single-unit three-stage screw compressor includes a first-stage compressor connected in series , the second-stage compressor and the third-stage compressor. The single-unit three-stage screw compressor is equipped with a refrigerant inlet, a refrigerant outlet, the first air supply port, the second air supply port and the oil return port, the refrigerant inlet and the gas-liquid The separator is connected, the refrigerant outlet is connected to the oil separator; the first air supply port is connected to the second economizer, the second air supply port is connected to the first economizer, the oil outlet of the oil separator is connected to the oil cooler, and then It is connected with the oil filter, solenoid valve and oil flow switch in turn, and finally connected with the oil return port of the single-unit three-stage screw compressor.

The screw-type single-unit three-stage compression heat pump heating system is characterized in that the first economizer and the second economizer are composed of two-stage flash economizers, the first stage is the first economizer, and the second stage is the second economizer. The economizer, the first economizer is connected with the second economizer through the second expansion valve.

The screw-type single-unit three-stage compression heat pump heating system is characterized in that it also includes a shell-and-tube condenser, and the water inlet and water outlet of the oil cooler and the shell-and-tube condenser are connected in parallel.

The screw type single-unit three-stage compression heat pump heating system is characterized in that the air outlet of the oil separator is connected to the D port of the four-way valve, and the C port of the four-way valve is connected to the air inlet of the shell-and-tube condenser , the S port of the four-way valve is connected to the air inlet of the gas-liquid separator, and the E port of the four-way valve is connected to the finned evaporator.

The screw-type single-unit three-stage compression heat pump heating system is characterized in that the air outlet of the shell-and-tube condenser is sequentially connected with the liquid pipe filter and the first electronic expansion valve and then the first economizer.

The screw-type single-unit three-stage compression heat pump heating system is characterized in that the second economizer is connected to the finned evaporator after passing through the third electronic expansion valve.

The screw-type single-unit three-stage compression heat pump heating system is characterized in that it also includes a buffer water tank, and the buffer water tank is connected to the water outlet and the water inlet of the screw-type single-unit three-stage compression heat pump heating system, and the buffer water tank There is also a circulating water pump between the water outlet of the screw type single-unit three-stage compression heat pump heating system.

The screw-type single-unit three-stage compression heat pump heating system is characterized in that it also includes a heating radiator and a second circulating water pump. The water inlet and outlet of the heating radiator are connected to the buffer water tank, and the second circulating water pump is set at Between the water inlet of the heating radiator and the buffer water tank.

A screw-type single-unit three-stage compression heat pump heating method is characterized in that the refrigerant is compressed three times by a single-unit three-stage screw compressor, and the compression becomes a high-temperature and high-pressure gaseous state, and the high-temperature and high-pressure gaseous refrigerant is condensed through a shell-and-tube type The device exchanges heat with the water, completes the heating of the water, and the refrigerant condenses, which is condensed into a liquid state of high temperature and high pressure, passes through the liquid pipe filter, and enters the flash type first after being throttled by the first electronic expansion valve. An economizer, which becomes a gas-liquid mixed state at medium temperature and medium pressure, and the gas in it is filled into the second gas supply port between the third-stage compressor and the second-stage compressor of the single-unit three-stage screw compressor; at the same time, the flash Part of the liquid refrigerant in the first economizer evaporates into a gaseous state and absorbs the heat of the rest of the liquid refrigerant. The rest of the liquid refrigerant is supercooled and enters the The flash type second economizer becomes a gas-liquid mixed state at medium temperature and medium pressure, and the gas in it is filled into the first gas supply port between the second stage compressor and the first stage compressor of the single-unit three-stage screw compressor , at the same time, part of the liquid refrigerant in the flash second economizer evaporates into a gaseous state, and absorbs the heat of the remaining part of the liquid refrigerant, and the remaining part of the liquid refrigerant is supercooled; after two times of supercooling, the liquid refrigerant The refrigerant enters the finned evaporator after being throttled by the third electronic expansion valve, exchanges heat with the outdoor air at -40°C, is evaporated into a low-temperature and low-pressure gas state, and returns to the single unit after passing through the four-way valve and the gas-liquid separator. The three-stage screw compressor enters the next cycle.

The heating method of the screw-type single-unit three-stage compression heat pump is characterized in that it also includes a heating step, the heated high-temperature water enters the buffer water tank through the circulating water pump, and circulates to heat the water in the buffer water tank; The high-temperature water in the buffer water tank is pumped into the heating radiator, and the space is heated through the heating radiator.

The heating method of the screw-type single-unit three-stage compression heat pump is characterized in that the single-unit three-stage screw compressor sucks the low-temperature and low-pressure gaseous refrigerant R134a, and the first-stage compression raises its pressure from less than 0.29 bar to 1-2 bar , The second stage of compression further increases its pressure to 6-8bar, and the third stage of compression further increases to more than 35bar.

The heating method of the screw-type single-unit three-stage compression heat pump is characterized in that it also includes an oil separation process, and the high-temperature and high-pressure gas after the three-stage compression of the single-unit three-stage screw compressor is input to the oil separator, and the oil is separated. The compressor separates the lubricating oil of the compressor carried by the high-temperature and high-pressure gaseous refrigerant R134a. The separated lubricating oil is further cooled by heat exchange between the oil cooler and water, filtered by the oil filter, and then passed through the solenoid valve and the oil flow switch. Finally, it is divided into three routes and returned to the oil return port of the compressor.

The implementation of the present invention has the following beneficial effects: to solve the problems of existing air source heat pumps because the compression ratio exceeds the limit, the outlet water temperature is low and the use environment is narrow. Boilers are convenient for installation and transformation, economical and quick, energy-saving and environmentally friendly, and are a better heating technology solution.

Description of drawings

Figure 1 is a connection block diagram of a screw type single-unit three-stage compression heat pump heating system;

Figure 2 is an explanatory diagram of a single-unit three-stage screw compressor;

Figure 3 is a connection block diagram of the heating part of the subsystems.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

When the air source heat pump system needs to produce 90°C high-temperature hot water in an extremely cold environment of -40°C, it is necessary to compress the R134a refrigerant from an absolute pressure of 0.29 bar to an absolute pressure of 35.9 bar, using single-stage compression with a compression ratio of 120, Two-stage compression is adopted, the compression ratio of each stage is 11, and the compressors have greatly exceeded the limit range. The screw type single-unit three-stage compressed air source heat pump system of the present invention adopts a single-unit three-stage screw compressor, and a single screw compressor can Compress R134a refrigerant three times, through three-stage compression technology, the first stage compression increases its pressure from 0.29bar to 1.44bar, the second stage compression increases its pressure from 1.44bar to 7.2bar, and the third stage compression increases its pressure The pressure is increased from 7.2bar to 35.9bar, and the compression ratio of each stage is evenly distributed. The compression ratio of each stage is less than 5, and the compression ratio is controlled within the ideal range to achieve a high temperature of 90°C in an extremely cold environment of -40°C. hot water function.

Figure 2 is an explanatory diagram of a single-unit three-stage screw compressor. The single-unit three-stage screw compressor A includes a first-stage compressor A1, a second-stage compressor A2, and a third-stage compressor A3 connected in series. The screw compressor is provided with a refrigerant inlet, a refrigerant outlet, a first air supply port A4, a second air supply port A5 and an oil return port.

Figure 1 is a connection block diagram of a screw-type single-unit three-stage compression heat pump heating system. The refrigerant inlet of the single-unit three-stage screw compressor A is connected to the gas-liquid separator 12, and the refrigerant outlet is connected to the oil separator 2; the second air supply port A5 is connected to the first economizer 7, and the first air supply port A4 is connected to the The second economizer 9 is now connected; the first economizer 7 and the second economizer 9 are composed of two-stage flash economizers, the first stage is the first economizer 7, the second stage is the second economizer 9, and the second stage is the second economizer 9. An economizer 7 is connected with a second economizer 9 through a second expansion valve 8 . A two-stage flash economizer is used to supercool the liquid refrigerant coming out of the condenser twice, increasing the enthalpy of the liquid refrigerant, and to replenish the compressor in two stages to reduce the operating temperature of the compressor motor , There is no temperature difference in the heat exchange process of the flash economizer, and the efficiency of the heat pump system is increased by more than 50%.

The oil outlet of the oil separator 2 is connected to the oil cooler 16, and then connected to the oil filter 13, the solenoid valve 14 and the oil flow switch 15 in turn, and finally connected to the oil return port of the single-unit three-stage screw compressor. The gas outlet of the oil separator 2 is connected to the D port of the four-way valve 1, the C port of the four-way valve 1 is connected to the air inlet of the shell-and-tube condenser 4, and the S port of the four-way valve 1 is connected to the gas-liquid separator. The air inlet is connected, and the E port of the four-way valve 1 is connected with the finned evaporator 17 . The gas outlet of the shell-and-tube condenser 4 is sequentially connected with the liquid pipe filter 5 and the first electronic expansion valve 6 and then with the first economizer 7 . The second economizer 9 is connected to the finned evaporator 17 after passing through the third electronic expansion valve 10 .

The water inlet and outlet of the oil cooler and the shell-and-tube condenser are connected in parallel. A water-cooled oil cooler is adopted, and the water inlet and outlet are connected in parallel with the water inlet and outlet of the shell-and-tube condenser, which not only controls the temperature of the lubricating oil reasonably, but also has a reasonable viscosity of the lubricating oil. When it returns to the compressor, the compressor is well lubricated and improves The stability and working efficiency of the compressor, at the same time, the heat of the lubricating oil heats the hot water, recovering the heat of the lubricating oil, and further improving the working efficiency of the heat pump system.

The heating system can also be composed of a screw-type single-unit three-stage compressed air source heat pump unit, a buffer water tank, a radiator, and valves on the waterway. When heating, the unit stores heat in the buffer water tank. When the water temperature reaches 90°C, The unit stops running. At this time, the heating load is provided by the buffer water tank. When the temperature of the buffer water tank drops to 80°C, the unit starts to run, and the heat is stored in the buffer water tank again, and the cycle is repeated. The frequency of starting and stopping of the unit is reduced, which solves the problem. The existing air source heat pump heating frequently starts and stops, the life of the unit is short, and the stability and comfort of the heating system are poor.

The following describes its specific working principle:

One: hot water mode. The single three-stage screw compressor sucks the low-temperature and low-pressure gaseous refrigerant R134a, the first stage compressor increases its pressure from 0.29bar to 1.44bar, the second stage compressor increases its pressure from 1.44bar to 7.2bar, and the second stage compressor increases its pressure from 1.44bar to 7.2bar. The three-stage compressor increases its pressure from 7.2bar to 35.9bar. The low-temperature and low-pressure gaseous refrigerant R134a is compressed three times by the compressor and becomes a high-temperature and high-pressure gaseous state, and enters the oil separator. The high-temperature and high-pressure gaseous refrigerant R134a carries The lubricating oil of the compressor is separated in the oil separator, and the lubricating oil passes through the oil cooler to exchange heat with water to reduce the temperature, is filtered through the oil filter, then passes through the solenoid valve and the oil flow switch, and finally returns to the oil return port of the compressor in three equal ways ;The high-temperature and high-pressure gaseous refrigerant R134a separated from the lubricating oil passes through the four-way valve and enters the shell-and-tube condenser to exchange heat with water, heating the water to 90°C, which is condensed into a high-temperature and high-pressure liquid, and filtered through the liquid pipe After being throttled by the first electronic expansion valve, it enters the flash type first economizer, and becomes a gas-liquid mixed state at medium temperature and pressure, and the gas in it is fed into the third stage and the At the second air supply port in the middle of the second stage, at the same time, part of the liquid refrigerant in the flash first economizer evaporates into a gaseous state, and absorbs the heat of the remaining part of the liquid refrigerant, and the remaining part of the liquid refrigerant is overheated. After being throttled by the second electronic expansion valve, it enters the flash type second economizer, and becomes a gas-liquid mixed state of medium temperature and pressure, and the gas state is filled into the second stage and the second stage of the single-unit three-stage screw compressor. At the first air supply port in the middle of the first stage, at the same time, part of the liquid refrigerant in the flash second economizer evaporates into a gaseous state and absorbs the heat of the remaining part of the liquid refrigerant, and the remaining part of the liquid refrigerant is overheated Cold; the liquid refrigerant that has been subcooled twice enters the finned evaporator after being throttled by the third electronic expansion valve, exchanges heat with the outdoor air at -40°C, is evaporated into a low-temperature and low-pressure gaseous state, and passes through the four-way After the valve and the gas-liquid separator, return to the single-unit three-stage screw compressor to enter the next cycle.

2. Heating mode:

Fig. 3 is a connection block diagram of the sub-systems of the heating part. The screw type single-unit three-stage compression heat pump heating system also includes a buffer water tank 21, and the buffer water tank 21 is connected with the water outlet and the water inlet of the screw type single-unit three-stage compression heat pump heating system. There is also a circulating water pump 22 between the water outlet of the screw type single-unit three-stage compression heat pump heating system, and a filter can also be added to filter the circulating water quality. It also includes a heating radiator 23 and a second circulating water pump 24, the water inlet and outlet of the heating radiator 23 are connected to the buffer water tank 21, and the second circulating water pump 24 is arranged between the water inlet of the heating radiator and the buffer water tank. The circulating water pump sucks the water in the buffer water tank and pumps it to the water inlet of the screw type single-unit three-stage compressed air source heat pump. The circulating water pump is sucked into the next cycle until the hot water in the buffer tank is heated to 90°C; at the same time, the 90°C hot water in the buffer tank is sucked by the second circulating pump, and enters the heating radiator through the ball valve and the diverter valve. The heating radiator dissipates heat and heats the indoor air. After the hot water is cooled, it returns to the buffer water tank through the diverter valve, ball valve, check valve, filter, expansion tank 25, and circulating water pump to enter the next cycle. When the buffer water tank needs to replenish water, open the water replenishment ball valve at the bottom, the replenishment water enters the main circulation pipeline through the ball valve and the one-way valve, mixes with the hot water from the heating radiator, passes through the filter, the expansion tank, and the circulating water pump and enters the buffer water tank . Antifreeze is added to the expansion tank, and necessary ball valves are installed on each water channel as required.

What is disclosed above is only a kind of embodiment of the present invention, certainly can not limit the scope of rights of the present invention with this, those of ordinary skill in the art can understand the whole or part of flow process that realizes above-mentioned embodiment, and make according to the claims of the present invention The equivalent changes still belong to the scope covered by the invention.

Claims (9)

1. A screw-type single-unit three-stage compression heat pump heating system is characterized in that it comprises a single-unit three-stage screw compressor, and the single-unit three-stage screw compressor includes a first-stage compressor, a second-stage compressor and a first-stage compressor connected in series. Three-stage compressor, a single-unit three-stage screw compressor is equipped with a refrigerant inlet, a refrigerant outlet, a first air supply port, a second air supply port and an oil return port, the refrigerant inlet is connected to the gas-liquid separator, and the refrigerant outlet Connected to the oil separator; the first air supply port is connected to the second economizer, the second air supply port is connected to the first economizer, the oil outlet of the oil separator is connected to the oil cooler, and then sequentially connected to the oil filter and solenoid valve It is connected with the oil flow switch, and finally connected with the oil return port of the single-unit three-stage screw compressor. 2. The screw-type single-unit three-stage compression heat pump heating system according to claim 1, characterized in that the first economizer and the second economizer are composed of two-stage flash economizers, the first stage is the first economizer, The second stage is the second economizer, the first economizer is connected to the second economizer through the second expansion valve; it also includes a shell-and-tube condenser, the oil cooler and the water inlet and outlet of the shell-and-tube condenser in parallel. 3. The screw type single-unit three-stage compression heat pump heating system according to claim 2, characterized in that the air outlet of the oil separator is connected to the D port of the four-way valve, and the C port of the four-way valve is connected to the shell-and-tube type The air inlet of the condenser is connected, the S port of the four-way valve is connected with the air inlet of the gas-liquid separator, and the E port of the four-way valve is connected with the finned evaporator; the air outlet of the shell-and-tube condenser is sequentially connected with the liquid pipe filter The first economizer and the first electronic expansion valve are connected to the first economizer; the second economizer is connected to the finned evaporator after passing through the third electronic expansion valve. 4. The screw-type single-unit three-stage compression heat pump heating system according to claim 3, characterized in that it also includes a buffer water tank, and the buffer water tank is connected to the water outlet and the water inlet of the screw-type single-unit three-stage compression heat pump heating system A circulating water pump is also provided between the buffer water tank and the water outlet of the screw-type single-machine three-stage compression heat pump heating system. 5. The screw-type single-unit three-stage compression heat pump heating system according to claim 4, further comprising a heating radiator and a second circulating water pump, the water inlet and outlet of the heating radiator are connected to the buffer water tank, The second circulating water pump is arranged between the water inlet of the heating radiator and the buffer water tank. 6. A heating method for a screw-type single-unit three-stage compression heat pump, which is characterized in that the refrigerant is compressed three times by a single-unit three-stage screw compressor, and the compression becomes a high-temperature and high-pressure gaseous state, and the high-temperature and high-pressure gaseous refrigerant passes through the shell tube The type condenser exchanges heat with the water, completes the heating of the water, and the refrigerant condenses, which is condensed into a high-temperature and high-pressure liquid, passes through the liquid pipe filter, and enters the flash after being throttled by the first electronic expansion valve. The first economizer of the type becomes a gas-liquid mixed state of medium temperature and medium pressure, and the gas state in it is filled into the second air inlet between the third-stage compressor and the second-stage compressor of the single-unit three-stage screw compressor; at the same time , part of the liquid refrigerant in the flash-type first economizer evaporates into a gaseous state, and absorbs the heat of the remaining part of the liquid refrigerant, and the remaining part of the liquid refrigerant is supercooled, and is throttled by the second electronic expansion valve After entering the flash type second economizer, it becomes a gas-liquid mixed state of medium temperature and medium pressure, and the gas state is filled into the second-stage compressor of the single-unit three-stage screw compressor and the first stage between the first-stage compressor. At the same time, part of the liquid refrigerant in the flash second economizer evaporates into a gaseous state and absorbs the heat of the remaining part of the liquid refrigerant, and the remaining part of the liquid refrigerant is supercooled; after two times of supercooling The liquid refrigerant enters the finned evaporator after being throttled by the third electronic expansion valve, exchanges heat with the outdoor air at -40°C, is evaporated into a low-temperature and low-pressure gas state, and returns to the evaporator after passing through the four-way valve and the gas-liquid separator. To the single-unit three-stage screw compressor to enter the next cycle. 7. The method for heating with a screw-type single-unit three-stage compression heat pump according to claim 6, further comprising a heating step, the heated high-temperature water enters the buffer water tank through a circulating water pump, and the water in the buffer water tank is heated by circulation; The high-temperature water in the buffer water tank is pumped into the heating radiator through the second circulating water pump, and the space is heated through the heating radiator. 8. The method for heating with a screw-type single-unit three-stage compression heat pump according to claim 7, characterized in that the single-unit three-stage screw compressor sucks the low-temperature and low-pressure gaseous refrigerant R134a, and the first-stage compression reduces its pressure from less than 0.29 The bar is increased to 1-2 bar, the second-stage compression further increases its pressure to 6-8 bar, and the third-stage compression further increases to more than 35 bar. 9. The method for heating with a screw-type single-unit three-stage compression heat pump according to claim 8, characterized in that it also includes an oil separation process, and the high-temperature and high-pressure gas after the three-stage compression of the single-unit three-stage screw compressor is input into the Oil separator, the oil separator separates the compressor lubricating oil carried by the high-temperature and high-pressure gaseous refrigerant R134a, and the separated lubricating oil is further cooled by heat exchange with water through the oil cooler, filtered through the oil filter, and then passed through the electromagnetic valve and oil flow switch, and finally return to the oil return port of the compressor in three equal ways.