CN121089203A - Precise air conditioner energy-saving refrigerating system based on double-cold-source switching - Google Patents

Abstract

This invention relates to a precision air conditioning energy-saving refrigeration system based on dual-source switching, belonging to the field of air conditioning and refrigeration technology. It includes: an indoor unit with a dual-source evaporator coil; a first refrigeration circuit comprising a compressor, an outdoor condenser, a throttling valve, and a first coil circuit of the dual-source evaporator coil connected in sequence; a second refrigeration circuit comprising an external cold source interface, a circulating water pump, a first switching valve, a second coil circuit of the dual-source evaporator coil, and a second switching valve connected in sequence; and a control unit including a PLC controller and several sensors installed indoors and outdoors. This invention features intelligent and precise mode switching and collaborative control strategies, intelligently switching between direct evaporative refrigeration and natural cooling/chilled water refrigeration dual cold sources to adapt to changes in the external environment, always selecting the lowest energy consumption operating mode to avoid significant energy waste, thereby achieving excellent energy-saving effects and high operational reliability, preventing the risk of downtime.

Description

Precise air conditioner energy-saving refrigerating system based on double-cold-source switching

Technical Field

The invention relates to a precise air conditioner energy-saving refrigeration system based on double-cold-source switching, and belongs to the technical field of air conditioner refrigeration.

Background

In life, a vertical air conditioner and a hanging air conditioner are used at home, and air conditioners, precision air conditioners, also called constant temperature and humidity air conditioners, are also used on automobiles and large-scale equipment which needs manual control outdoors, and are air conditioning equipment specially designed for meeting the high-precision temperature and humidity control requirements of specific environments. They are widely used in data centers, communication base stations, medical equipment rooms, laboratories, and other critical environments. Conventional precision air conditioning systems mostly employ a single direct evaporative (DX) refrigeration scheme, i.e., refrigeration is achieved by a compressor performing a compression-condensation-expansion-evaporation cycle on a refrigerant.

The single cold source system can basically meet the normal use, but has the following main problems that the compressor is a core energy consumption component of the refrigeration system, the compressor needs to be started for refrigeration in the whole year operation no matter the outdoor environment temperature, the energy efficiency ratio COP of the system is limited, particularly, the compressor is continuously used for refrigeration in the period of low outdoor temperature such as spring and autumn or night, and huge energy waste is caused, the reliability is low, the refrigeration capacity of the whole system is completely dependent on the refrigeration loop of the compressor, and once the compressor or related key components thereof are in failure, such as a condenser and an expansion valve, the whole precision air conditioning system is at risk of shutdown.

Based on the above, the invention provides a precise air conditioner energy-saving refrigeration system based on double-cold-source switching.

Disclosure of Invention

The invention aims to solve the technical problems of high energy consumption, huge energy waste caused by the fact that a compressor needs to be started for refrigeration, low reliability and complete dependence on the refrigeration of the compressor, and the risk of shutdown is faced once the critical part fails.

The invention provides a precise air conditioner energy-saving refrigeration system based on double-cold-source switching, which adopts the technical proposal that:

The indoor unit is internally provided with a double-source evaporation coil pipe for heat exchange with indoor air;

The first refrigeration loop is used as a direct evaporation type refrigeration cold source and comprises a compressor, an outdoor condenser, a throttle valve and a first coil loop of the double-source evaporation coil which are sequentially connected;

The second refrigeration loop is used as a natural cooling or chilled water refrigeration cold source and comprises an external cold source interface, a circulating water pump, a first switching valve, a second coil loop of the double-source evaporation coil and a second switching valve which are connected in sequence;

The control unit comprises a PLC controller and a plurality of sensors arranged inside and outside a room, wherein the PLC controller is electrically connected with the compressor, the circulating water pump, the first switching valve, the second switching valve and the plurality of sensors respectively, and the control unit is used for automatically switching between at least three operation modes according to collected indoor and outdoor parameters and system operation states:

A direct evaporation refrigeration mode, in which the first refrigeration loop is started and the second refrigeration loop is closed;

a natural cooling mode, namely starting the second refrigeration loop and closing the first refrigeration loop;

And in a mixed refrigeration mode, the first refrigeration loop and the second refrigeration loop are started simultaneously.

Furthermore, the dual-source evaporation coil is of an integrated structure, the first coil loop is used for circulating a refrigerant, the second coil loop is used for circulating cooling water or glycol solution, and the first coil loop and the second coil loop share closely contacted fins for efficient heat exchange.

Further, the plurality of sensors comprise an indoor return air temperature sensor, an indoor air supply temperature sensor, an outdoor environment temperature sensor, a second refrigeration loop water inlet temperature sensor and a second refrigeration loop water outlet temperature sensor.

Further, the throttle valve is an electronic expansion valve, and the control unit accurately adjusts the opening of the electronic expansion valve according to the superheat degree of the outlet of the second coil loop through a PID or fuzzy PID control algorithm so as to optimize the refrigeration efficiency.

Further, the first refrigeration circuit further includes a dry filter between the outdoor condenser and the throttle valve for filtering moisture and impurities in the refrigerant.

Further, the external cold source interface can be connected to a cooling tower, a main cooler or a central chilled water system of a building, and the first switching valve and the second switching valve are electric three-way valves for controlling cooling water to flow into or bypass the second coil loop.

Further, the second refrigeration loop also comprises a cold accumulation tank, wherein the cold accumulation tank is positioned between the circulating water pump and the first switching valve and is used for storing cold energy in the electricity price valley period or when the natural cold source is sufficient, and releasing the cold energy when needed so as to realize peak clipping and valley filling and further energy saving.

The invention has the beneficial effects that:

The intelligent switching system can intelligently and finely switch modes and cooperatively control strategies, the intelligent switching of direct evaporative refrigeration and natural cooling/chilled water refrigeration double cold sources is suitable for external environment changes, and the working mode with the lowest energy consumption is always selected, so that huge energy waste is avoided, and therefore excellent energy-saving effect and high operation reliability are realized, and the occurrence of shutdown risk is prevented.

Drawings

Fig. 1 is a block diagram of the structure of the present invention.

FIG. 2 is a schematic diagram of several sensors according to the present invention.

Fig. 3 is a schematic diagram of the refrigerant flow of the first refrigeration circuit of the present invention.

Fig. 4 is a schematic diagram of the cooling water flow of the second refrigeration circuit of the present invention.

Fig. 5 is a schematic diagram of the operation mode of the control unit according to the present invention.

1. The system comprises an indoor unit, a double-source evaporation coil, a first refrigerating loop, a second refrigerating loop, a control unit and a control unit, wherein the indoor unit is provided with the double-source evaporation coil;

30. the device comprises a compressor, 31, an outdoor condenser, 32, a throttle valve, 33, a first coil loop, 34, a dry filter, 40, an external cold source interface, 41, a circulating water pump, 42, a first switching valve, 43, a second coil loop, 44, a second switching valve, 45, a cold storage tank, 50, a PLC controller, 51, a sensor, 510, an indoor return air temperature sensor, 511, an indoor air supply temperature sensor, 512, an outdoor environment temperature sensor, 513, a second refrigerating loop water inlet temperature sensor, 514 and a second refrigerating loop water outlet temperature sensor.

Detailed Description

Preferred embodiments of the present invention will be described in detail below.

According to the invention, as shown in figures 1-5, the invention provides a precise air conditioner energy-saving refrigeration system based on double-cold-source switching, which comprises:

The indoor unit 1, the indoor unit 1 is internally provided with a double-source evaporation coil 2, the indoor unit 1 is installed in a machine room needing to be subjected to environment control, and mainly comprises a machine case and an EC frequency conversion centrifugal fan, the EC fan is responsible for driving indoor air circulation, air is sucked from a front return grid of the machine room and is sent out through an underfloor or upper air supply opening after being cooled and cooled by the double-source evaporation coil 2, the double-source evaporation coil 2 integrates two independent fluid channels and is used for carrying out heat exchange with indoor air, the double-source evaporation coil 2 is of an integrated structure, and a first coil loop 33 and a second coil loop 43 share closely contacted fins for carrying out efficient heat exchange;

The first refrigeration loop 3 is a complete vapor compression refrigeration cycle as a main direct evaporation type refrigeration cold source, and comprises a compressor 30, an outdoor condenser 31, a throttle valve 32 and a first coil loop 33 of a double-source evaporation coil 2 which are sequentially connected, wherein the first coil loop 33 is used for circulating refrigerant, the first refrigeration loop 3 also comprises a dry filter 34 positioned between the outdoor condenser 31 and the throttle valve 32 and is used for filtering moisture and impurities in the refrigerant, the throttle valve 32 is an electronic expansion valve, the control unit 5 precisely adjusts the opening degree of the electronic expansion valve according to the superheat degree of the outlet of the second coil loop 43 through a PID or fuzzy PID control algorithm so as to optimize the refrigeration efficiency, the first refrigeration loop 3 is formed by sequentially connecting refrigerant pipelines in series, the loop is responsible for providing strong refrigeration capacity when the ambient temperature is higher or the indoor load is higher, the compressor 30 adopts a high-efficiency fully-closed scroll variable frequency compressor, is responsible for compressing low-temperature low-pressure gas refrigerant, the outdoor condenser 31 is arranged outdoors, a V-shaped coil and an axial-flow variable-frequency fan is adopted for discharging high-pressure gas refrigerant from the high-pressure condenser 31 to the first coil loop 30, and the high-pressure air compressor is responsible for compressing the high-pressure air compressor 33, and the high-pressure refrigerant is in the closed-pressure circulation loop 30.

The second refrigeration loop 4 is a water/glycol solution circulation system as a natural cooling or chilled water refrigeration cold source, and comprises an external cold source interface 40, a circulating water pump 41, a first switching valve 42, a second coil loop 43 of the double-source evaporation coil 2 and a second switching valve 44 which are sequentially connected, wherein the second coil loop 43 is used for circulating cooling water or glycol solution, the external cold source interface 40 comprises a water inlet 4a and a water outlet 4b, and can be connected to an external cooling water system such as a cooling tower, a closed type drier or a building central chilled water main pipe, so that low-temperature cooling water is utilized for direct refrigeration, the first switching valve 42 and the second switching valve 44 are electric three-way valves for controlling the cooling water to flow into or bypass the second coil loop 43, the second refrigeration loop 4 also comprises a cold storage tank 45, the cold storage tank 45 is positioned between the circulating water pump 41 and the first switching valve 42 and used for storing cold energy when the electric price valley period or the natural cooling source is sufficient, and is released when needed so as to realize valley filling and further energy saving, the circulating water pump 41 adopts variable frequency driving peak to provide power for cooling water circulation, and the cooling water flows to the first switching valve 4a and the second switching valve 44 and the first switching valve 41 and the second switching valve 4b.

The control unit 5, including the PLC controller 50, a plurality of sensors 51 disposed inside and outside the room, the plurality of sensors 51 include indoor return air temperature sensor 510, indoor supply air temperature sensor 511, outdoor environment temperature sensor 512, second refrigeration circuit inlet water temperature sensor 513 and second refrigeration circuit outlet water temperature sensor 514, the PLC controller 50 is respectively with the compressor 30, the circulating water pump 41, the first switching valve 42, the second switching valve 44 and the plurality of sensors 51 electric connection, the control unit is the brain of the whole system, the PLC controller 50 is generally the siemens, schneider brand PLC, etc., the PLC controller 50 gathers the key parameters inside and outside the system in real time through the plurality of sensors 51, based on these data, the control unit 5 is used for carrying out automatic switching between at least three kinds of operation modes according to the indoor and outdoor environment parameters and the system operation state gathered:

a direct evaporation refrigeration mode, namely starting the first refrigeration loop 3 and closing the second refrigeration loop 4;

A natural cooling mode, namely starting the second refrigeration loop 4 and closing the first refrigeration loop 3;

And in the mixed refrigeration mode, the first refrigeration circuit 3 and the second refrigeration circuit 4 are started simultaneously.

The switching control logic built in the control unit 5 includes:

The outdoor environment temperature sensor 512 monitors outdoor temperature in real time, when the outdoor environment temperature is higher than a first preset temperature threshold (for example, 25 ℃), the system is switched to a direct evaporation refrigeration mode, the control unit 5 starts fans of the compressor 30 and the outdoor condenser 31, the frequency of the compressor 30 and the opening degree of the electronic expansion valve are adjusted according to indoor load through a fuzzy PID algorithm, the air supply temperature is accurately controlled, meanwhile, the circulating water pump 41 stops running, the first switching valve 42 and the second switching valve 44 are in a bypass state, the second refrigeration loop 4 does not work, and the system runs in a traditional precise air conditioning mode, so that the refrigeration capacity under severe environment is ensured;

When the outdoor ambient temperature is lower than a second preset temperature threshold (for example, 10 ℃), the second refrigerating circuit inlet water temperature sensor 513 detects that the temperature of the cooling water is low enough, the system is switched to a natural cooling mode, the control unit 5 completely closes the fans of the compressor 30 and the outdoor condenser 31, the variable-frequency circulating water pump 41 is started, the first switching valve 42 is switched to the full-pass position, the second switching valve 44 cooperates to make the cooling water flow through the second coil pipe loop 43 completely, the control unit 5 controls the cooling water flow by adjusting the rotating speed of the circulating water pump 41, so that the air supply temperature is accurately controlled, the natural cold source refrigeration can be completely relied, the power consumption of the compressor 30 is zero, the system energy consumption is reduced to the minimum, and the energy consumption of the water pump and the fans is only;

When the outdoor ambient temperature is between the first and second preset temperature thresholds, the system selects a direct evaporation refrigeration mode or a mixed refrigeration mode according to the indoor load condition, and in the mixed refrigeration mode, the control unit 5 pre-cools the indoor return air by the cooling water flowing through the second coil loop 43 by adjusting the opening of the first switching valve 42 and the rotation speed of the circulating water pump 41, and then deep refrigeration is performed by the first coil loop 33, so as to reduce the energy consumption of the compressor 30.

The system can intelligently switch the operation mode according to the outdoor temperature, preferably or completely uses the natural cooling mode under proper conditions, completely avoids the operation of the compressor, has extremely low energy consumption, greatly reduces the power consumption of the compressor by a precooling technology in a mixed mode, and comprehensively measures and calculates that the annual average energy saving rate of the system under typical load working conditions can reach 30% -50% compared with the traditional single cold source precise air conditioner. The comprehensive energy efficiency ratio (COP) of the system is greatly improved, the COP value can be improved to more than 7.0 from 3.5 of the traditional system under partial load, the energy saving effect is obvious, the system has higher operation reliability, the two independent cold source systems are mutually backup, when the first refrigerating circuit (compressor system) fails, if the environment condition allows, the second refrigerating circuit (natural cooling system) can still independently operate, certain emergency refrigerating capability is provided, the operation safety of core equipment is ensured, and vice versa, the redundancy design greatly improves the reliability and the usability of the whole air conditioning system.

The invention and its embodiments have been described above with no limitation, and the actual construction is not limited to the embodiments of the invention as shown in the drawings. In summary, if one of ordinary skill in the art is informed by this disclosure, a structural manner and an embodiment similar to the technical solution should not be creatively devised without departing from the gist of the present invention.

Claims (7)

1. The energy-saving refrigerating system of the precise air conditioner based on double-cold-source switching is characterized by comprising the following components:

an indoor unit (1), wherein a dual-source evaporation coil (2) for heat exchange with indoor air is arranged in the indoor unit (1);

The first refrigeration loop (3) is used as a direct evaporation type refrigeration cold source and comprises a compressor (30), an outdoor condenser (31), a throttle valve (32) and a first coil loop (33) of the double-source evaporation coil (2) which are connected in sequence;

The second refrigerating loop (4) is used as a natural cooling or chilled water refrigerating cold source and comprises an external cold source interface (40), a circulating water pump (41), a first switching valve (42), a second coil loop (43) of the double-source evaporating coil (2) and a second switching valve (44) which are sequentially connected;

the control unit (5) comprises a PLC (programmable logic controller) and a plurality of sensors (51) arranged inside and outside a room, wherein the PLC (50) is electrically connected with the compressor (30), the circulating water pump (41), the first switching valve (42), the second switching valve (44) and the plurality of sensors (51) respectively, and the control unit (5) is used for automatically switching between at least three operation modes according to collected indoor and outdoor environment parameters and system operation states:

a direct evaporation refrigeration mode, in which the first refrigeration circuit (3) is started and the second refrigeration circuit (4) is closed;

A natural cooling mode, in which the second refrigeration circuit (4) is started and the first refrigeration circuit (3) is closed;

and the mixed refrigeration mode is that the first refrigeration loop (3) and the second refrigeration loop (4) are started simultaneously.

2. The energy-saving refrigeration system of the precise air conditioner based on double-cold-source switching as set forth in claim 1, wherein the double-source evaporation coil (2) is of an integrated structure, the first coil loop (33) is used for circulating a refrigerant, the second coil loop (43) is used for circulating cooling water or glycol solution, and the first coil loop (33) and the second coil loop (43) share closely contacted fins for efficient heat exchange.

3. The energy-saving refrigerating system of the precise air conditioner based on double-cold-source switching as set forth in claim 1, wherein the plurality of sensors (51) comprises an indoor return air temperature sensor (510), an indoor air supply temperature sensor (511), an outdoor environment temperature sensor (512), a second refrigerating circuit inlet water temperature sensor (513) and a second refrigerating circuit outlet water temperature sensor (514).

4. The energy-saving refrigeration system of the precise air conditioner based on double-cold-source switching as set forth in claim 1, wherein the throttle valve (32) is an electronic expansion valve, and the control unit (5) precisely adjusts the opening of the electronic expansion valve according to the superheat degree of the outlet of the second coil loop (43) through a PID or fuzzy PID control algorithm to optimize the refrigeration efficiency.

5. The energy-saving refrigeration system of a precision air conditioner based on double-cold-source switching as set forth in claim 1, wherein said first refrigeration circuit (3) further comprises a dry filter (34) between an outdoor condenser (31) and a throttle valve (32) for filtering moisture and impurities in the refrigerant.

6. The energy-saving refrigeration system of a precise air conditioner based on double-cold-source switching as set forth in claim 1, wherein said external cold source interface (40) is connectable to a cooling tower, a main chiller or a central chilled water system of a building, and said first switching valve (42) and said second switching valve (44) are electric three-way valves for controlling the flow of cooling water into or bypassing said second coil circuit (43).

7. The energy-saving refrigerating system of the precise air conditioner based on double-cold-source switching as set forth in claim 1, wherein the second refrigerating circuit (4) further comprises a cold accumulation tank (45), and the cold accumulation tank (45) is located between the circulating water pump (41) and the first switching valve (42) and is used for storing cold energy during electricity price valley period or when natural cold source is sufficient, and releasing the cold energy when needed so as to realize peak clipping and valley filling and further energy saving.