Dual-system heating ventilation air conditioner and control method thereof

Abstract

The invention relates to the technical field of heating ventilation air conditioners, in particular to a dual-system heating ventilation air conditioner and a control method thereof.The dual-system heating ventilation air conditioner comprises an evaporator and a condenser and further comprises a first expansion valve, a first inverter compressor, a second expansion valve and a second inverter compressor, and the first inverter compressor, the condenser, the first expansion valve and the evaporator are communicated in a closed-loop mode through pipelines; one end of the condenser is connected with a water inlet pipe, the other end of the condenser is connected with a water outlet pipe, the operation matching mode of the first inverter compressor and the second inverter compressor is controlled in a feedback mode according to the change of the temperature of the application end, and therefore operation is more reasonable; noise is reduced, using energy efficiency is improved, the service life of the compressor is prolonged, and overhauling is convenient.

Description

Technical Field

[0001] The present invention relates to the technical field of heating, ventilation and air conditioning, and in particular to a dual-system heating, ventilation and air conditioning and a control method thereof. Background Art

[0002] HVAC refers to the system or related equipment responsible for heating, ventilation and air conditioning in a room or car. The HVAC system can control the temperature and humidity of the air and improve the indoor comfort. It is an important part of medium and large industrial buildings or office buildings. At present, HVAC adopts a single system with multiple compressors (the compressor inlet and outlet are installed in parallel) in commercial machines. However, this single-system installation method requires multiple compressors to be started and stopped at the same time under any circumstances, and the number of starts and stops is relatively large, resulting in loud noise, unreasonable operation, and reduced energy efficiency. Frequent starts and stops will shorten the service life of the compressor, and the compressor cannot be repaired without stopping, resulting in maintenance difficulties. Summary of the invention

[0003] In order to overcome the deficiencies of the prior art, the object of the present invention is to provide a dual-system HVAC and a control method thereof which has low noise, reasonable operation, improved energy efficiency, extended compressor service life and is easy to maintain.

[0004] The technical solution adopted by the present invention is:

[0005] A dual-system HVAC includes an evaporator and a condenser, and also includes a first expansion valve, a first variable frequency compressor, a second expansion valve and a second variable frequency compressor. The first variable frequency compressor, the condenser, the first expansion valve and the evaporator are connected in a closed loop through a pipeline, and the second variable frequency compressor, the condenser, the second expansion valve and the evaporator are connected in a closed loop through a pipeline. One end of the condenser is connected to a water inlet pipe, and the other end is connected to a water outlet pipe.

[0006] Preferably, it further includes a first four-way valve and a second four-way valve, the first four-way valve is provided with four first ports, two of which are respectively connected to the inlet and outlet of the first variable frequency compressor through pipelines, and the other two first ports are respectively connected to the evaporator and the condenser through pipelines, and the second four-way valve is provided with four second ports, two of which are respectively connected to the inlet and outlet of the second variable frequency compressor through pipelines, and the other two second ports are respectively connected to the evaporator and the condenser through pipelines.

[0007] Preferably, a fan is provided on one side of the evaporator.

[0008] Preferably, both the first expansion valve and the second expansion valve are electronic expansion valves.

[0009] The present invention also provides a dual-system HVAC control method, comprising the following steps:

[0010] S1, setting the target temperature value Ts of the HVAC, the first temperature difference T1, the second temperature difference T2, the third temperature difference T3, the fourth temperature difference T4, the temperature return difference T0, the compressor frequency setting value Fx, and the compressor operation time setting value t1;

[0011] S2, receiving a power-on command, detecting the current temperature value Tn of the application end in real time, and calculating the difference ΔT between the target temperature value Ts and the current temperature value Tn;

[0012] S3, determine whether ΔT is greater than or equal to T1, if so, proceed to step S4;

[0013] S4, controlling the first variable frequency compressor and the second variable frequency compressor to start running;

[0014] S5, determining whether ΔT is less than or equal to T3, if not, returning to step S4, if yes, reducing the operating frequencies of the first variable frequency compressor and the second variable frequency compressor, and making the first variable frequency compressor and the second variable frequency compressor operate for t1 time after the operating frequencies are reduced;

[0015] S6, determine whether ΔT is less than or equal to T4, if not, return to step S5, if yes, proceed to step S7;

[0016] S7, real-time detection of the current operating frequency F of the first variable frequency compressor and the second variable frequency compressor, and determination of whether F is less than or equal to Fx, if not, return to step S5, if yes, proceed to step S8;

[0017] S8, comparing the accumulated running time of the first variable frequency compressor and the accumulated running time of the second variable frequency compressor to obtain a first comparison result;

[0018] S9, controlling the variable frequency compressor with a long cumulative running time to stop running according to the first comparison result;

[0019] S10, controlling the remaining variable frequency compressors to continue to operate;

[0020] S11, determine whether Tn is greater than or equal to the sum of Ts and T0, if not, return to step S10, if yes, control the variable frequency compressor to stop running.

[0021] Preferably, after step S3, the method further comprises the following steps:

[0022] S12, if ΔT is less than T1, determine whether ΔT is greater than or equal to T2, if not, control the first variable frequency compressor and the second variable frequency compressor to remain in a standby state, if yes, proceed to step S13;

[0023] S13, comparing the accumulated running time of the first variable frequency compressor and the accumulated running time of the second variable frequency compressor to obtain a second comparison result;

[0024] S14, controlling the variable frequency compressor with the longest cumulative running time to maintain a standby state according to the second comparison result;

[0025] S15, controlling the remaining variable frequency compressors to start running;

[0026] S16, determine whether Tn is greater than or equal to the sum of Ts and T0, if not, return to step S15, if yes, control the variable frequency compressor to stop running.

[0027] The beneficial effects of the present invention are:

[0028] The dual-system HVAC and control method thereof feedback controls the operation coordination mode of the first variable frequency compressor and the second variable frequency compressor according to the change of the application end temperature, so as to make the operation more reasonable, reduce noise, improve energy efficiency, extend the service life of the compressor and facilitate maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the structure of a dual-system HVAC system.

[0030] Figure 2 A first flow chart of a control method for a dual-system HVAC system.

[0031] Figure 3 A second flow chart of the control method for a dual-system HVAC system.

[0032] In the figure: 1. Evaporator; 2. Condenser; 3. First expansion valve; 4. First variable frequency compressor; 5. Second expansion valve; 6. Second variable frequency compressor; 7. Water inlet pipe; 8. Water outlet pipe; 9. First four-way valve; 10. Second four-way valve; 11. Fan. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] See also Figure 1The present invention provides a technical solution: a dual-system HVAC, comprising an evaporator 1 and a condenser 2, and also comprising a first expansion valve 3, a first variable frequency compressor 4, a second expansion valve 5 and a second variable frequency compressor 6. The first variable frequency compressor 4, the condenser 2, the first expansion valve 3 and the evaporator 1 are connected in a closed loop through a pipeline, and the second variable frequency compressor 6, the condenser 2, the second expansion valve 5 and the evaporator 1 are connected in a closed loop through a pipeline. One end of the condenser 2 is connected to a water inlet pipe 7, and the other end is connected to a water outlet pipe 8. Liquid flows through the water inlet pipe 7 and the water outlet pipe 8, so that the liquid performs heat exchange with the refrigerant passing through the condenser 2;

[0035] The first variable frequency compressor 4, the condenser 2, the first expansion valve 3 and the evaporator 1 constitute a first refrigerant circulation system, and the second variable frequency compressor 6, the condenser 2, the second expansion valve 5 and the evaporator 1 constitute a second refrigerant circulation system;

[0036] The evaporator 1 or the condenser 2 is installed at the application end, and the operation coordination mode of the first variable frequency compressor 4 and the second variable frequency compressor 6 is feedback-controlled according to the temperature change at the application end, so that the operation is more reasonable, the noise is reduced, the energy efficiency is improved, the service life of the compressor is extended, and it is convenient for maintenance.

[0037] In order to facilitate the change of the direction of refrigerant flow, thereby realizing the functional interchange between the evaporator 1 and the condenser 2, in the present embodiment, preferably, a first four-way valve 9 and a second four-way valve 10 are also included, and the first four-way valve 9 is provided with four first ports, two of which are respectively connected to the inlet and outlet of the first variable frequency compressor 4 through pipelines, and the other two first ports are respectively connected to the evaporator 1 and the condenser 2 through pipelines, and the second four-way valve 10 is provided with four second ports, two of which are respectively connected to the inlet and outlet of the second variable frequency compressor 6 through pipelines, and the other two second ports are respectively connected to the evaporator 1 and the condenser 2 through pipelines, so that the evaporator 1 or the condenser 2 can be installed at the application end to improve applicability.

[0038] In order to improve the heat exchange efficiency between the surface of the evaporator 1 and the air, in this embodiment, preferably, a fan 11 is provided on one side of the evaporator 1, so as to improve the heat exchange efficiency between the surface of the evaporator 1 and the air by blowing air through the fan 11.

[0039] In order to improve the regulation accuracy of the refrigerant flow rate, in the present embodiment, preferably, the first expansion valve 3 and the second expansion valve 5 are both electronic expansion valves, so that the electronic expansion valves can accurately regulate the refrigerant flow rate through electronic control signals.

[0040] See also Figure 2 The present invention also provides a dual-system HVAC control method, comprising the following steps:

[0041] S1, set the target temperature value Ts of the HVAC, the first temperature difference T1, the second temperature difference T2, the third temperature difference T3, the fourth temperature difference T4, the temperature return difference T0, the compressor frequency setting value Fx, and the compressor operation time setting value t1, T3>T1>T4>T2;

[0042] S2, receiving a power-on command, detecting the current temperature value Tn of the application end in real time, and calculating the difference ΔT between the target temperature value Ts and the current temperature value Tn;

[0043] S3, determine whether ΔT is greater than or equal to T1, if so, it indicates that the temperature of the application end is low at this time, then go to step S4;

[0044] S4, controlling the first variable frequency compressor 4 and the second variable frequency compressor 6 to start running;

[0045] S5, judging whether ΔT is less than or equal to T3, if not, indicating that the temperature of the application end is still relatively low at this time, then returning to step S4, if yes, indicating that the temperature of the application end rises to a certain temperature range at this time, then reducing the operating frequencies of the first variable frequency compressor 4 and the second variable frequency compressor 6, and making the first variable frequency compressor 4 and the second variable frequency compressor 6 run for t1 time after reducing the operating frequencies;

[0046] S6, determine whether ΔT is less than or equal to T4, if not, it indicates that the temperature of the application end has not further increased to the next temperature range, then return to step S5, if yes, it indicates that the temperature of the application end has increased to the next temperature range, then enter step S7;

[0047] S7, real-time detection of the current operating frequency F of the first variable frequency compressor 4 and the second variable frequency compressor 6, and determination of whether F is less than or equal to Fx, if not, indicating that the current operating frequency F in this temperature range can be further reduced to improve energy efficiency, then return to step S5, if yes, indicating that the current operating frequency F has reached the requirement, then proceed to step S8;

[0048] S8, comparing the accumulated running time of the first variable frequency compressor 4 and the accumulated running time of the second variable frequency compressor 6 to obtain a first comparison result;

[0049] S9, according to the first comparison result, the variable frequency compressor with the longest cumulative running time is controlled to stop running. In this step, the cumulative running time of the two variable frequency compressors after multiple uses can be ensured to be equal, so as to prevent one of the variable frequency compressors from being used for too long, thereby extending the service life of the compressor. Moreover, when one of the variable frequency compressors stops running, it can be repaired, so as to achieve the effect of non-stop maintenance of the HVAC, and improve the convenience of maintenance;

[0050] S10, controlling the remaining variable frequency compressors to continue to operate. In this step, it can be ensured that the accumulated operating time of the two variable frequency compressors after multiple uses tends to be equal, thereby preventing one of the variable frequency compressors from being used for too short a time;

[0051] S11. Determine whether Tn is greater than or equal to the sum of Ts and T0. If not, it indicates that the actual temperature hysteresis value obtained by subtracting the target temperature value Ts from the current temperature value Tn of the application end is less than the set temperature hysteresis value T0, then return to step S10. If so, it indicates that the actual temperature hysteresis value obtained by subtracting the target temperature value Ts from the current temperature value Tn of the application end is greater than or equal to the set temperature hysteresis value T0. At this time, the temperature of the application end is too high, then the variable frequency compressor is controlled to stop running to achieve energy saving effect.

[0052] See also Figure 3 In order to further make the compressor run more reasonably, reduce noise, improve energy efficiency, extend the service life of the compressor and facilitate maintenance, in this embodiment, preferably, the following steps are further included after step S3:

[0053] S12, if ΔT is less than T1, indicating that the temperature of the application end is relatively high at this time, then determine whether ΔT is greater than or equal to T2, if not, indicating that the temperature of the application end has reached a certain temperature range at this time, then control the first variable frequency compressor 4 and the second variable frequency compressor 6 to maintain a standby state, if yes, indicating that the temperature of the application end has not reached a certain temperature range at this time, then enter step S13;

[0054] S13, comparing the accumulated running time of the first variable frequency compressor 4 and the accumulated running time of the second variable frequency compressor 6 to obtain a second comparison result;

[0055] S14, according to the second comparison result, the variable frequency compressor with the longest cumulative running time is controlled to remain in a standby state. In this step, the cumulative running time of the two variable frequency compressors after multiple uses can be ensured to be equal, so as to prevent one of the variable frequency compressors from being used for too long, thereby extending the service life of the compressor. Moreover, when one of the variable frequency compressors stops running, it can be repaired, so as to achieve the effect of non-stop maintenance of the HVAC, and improve the convenience of maintenance;

[0056] S15, controlling the remaining variable frequency compressors to start running. In this step, it can be ensured that the accumulated running time of the two variable frequency compressors after multiple uses tends to be equal, preventing one of the variable frequency compressors from being used for too short a time;

[0057] S16, determine whether Tn is greater than or equal to the sum of Ts and T0. If not, it indicates that the actual temperature hysteresis value obtained by subtracting the target temperature value Ts from the current temperature value Tn of the application end is less than the set temperature hysteresis value T0, then return to step S15. If yes, it indicates that the actual temperature hysteresis value obtained by subtracting the target temperature value Ts from the current temperature value Tn of the application end is greater than or equal to the set temperature hysteresis value T0. At this time, the temperature of the application end is too high, then the variable frequency compressor is controlled to stop running to achieve the effect of energy saving;

[0058] Multiple compressors do not need to run at the same time when in use, which reduces noise and facilitates maintenance. It can also reduce the number of starts and stops of each compressor and extend the service life of the compressor. By feedback controlling the operation coordination of multiple compressors based on temperature changes at the application end, the operation is more reasonable, without wasting energy, and improving energy efficiency.

[0059] Finally, it should be noted that the above description is only a preferred example of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A dual-system HVAC system, comprising an evaporator (1) and a condenser (2), characterized in that: The invention also comprises a first expansion valve (3), a first variable frequency compressor (4), a second expansion valve (5) and a second variable frequency compressor (6); the first variable frequency compressor (4), the condenser (2), the first expansion valve (3) and the evaporator (1) are connected in a closed loop through a pipeline; the second variable frequency compressor (6), the condenser (2), the second expansion valve (5) and the evaporator (1) are connected in a closed loop through a pipeline; one end of the condenser (2) is connected to a water inlet pipe (7) and the other end is connected to a water outlet pipe (8).

2. A dual-system HVAC system according to claim 1, characterized in that: The invention also comprises a first four-way valve (9) and a second four-way valve (10), wherein the first four-way valve (9) is provided with four first ports, wherein two of the first ports are respectively connected to the inlet and outlet of the first variable frequency compressor (4) through pipelines, and the other two of the first ports are respectively connected to the evaporator (1) and the condenser (2) through pipelines, and the second four-way valve (10) is provided with four second ports, wherein two of the second ports are respectively connected to the inlet and outlet of the second variable frequency compressor (6) through pipelines, and the other two of the second ports are respectively connected to the evaporator (1) and the condenser (2) through pipelines.

3. A dual-system HVAC system according to claim 1, characterized in that: A fan (11) is provided on one side of the evaporator (1).

4. A dual-system HVAC system according to claim 1, characterized in that: The first expansion valve (3) and the second expansion valve (5) are both electronic expansion valves.

5. A control method for a dual-system HVAC system according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, setting the target temperature value Ts of the HVAC, the first temperature difference T1, the second temperature difference T2, the third temperature difference T3, the fourth temperature difference T4, the temperature return difference T0, the compressor frequency setting value Fx, and the compressor operation time setting value t1; S2, receiving a power-on command, detecting the current temperature value Tn of the application end in real time, and calculating the difference ΔT between the target temperature value Ts and the current temperature value Tn; S3, determine whether ΔT is greater than or equal to T1, if so, proceed to step S4; S4, controlling the first variable frequency compressor (4) and the second variable frequency compressor (6) to start operation; S5, determining whether ΔT is less than or equal to T3, if not, returning to step S4, if yes, reducing the operating frequencies of the first variable frequency compressor (4) and the second variable frequency compressor (6), and making the first variable frequency compressor (4) and the second variable frequency compressor (6) operate for a time period of t1 after the operating frequencies are reduced; S6, determine whether ΔT is less than or equal to T4, if not, return to step S5, if yes, proceed to step S7; S7, detecting the current operating frequency F of the first variable frequency compressor (4) and the second variable frequency compressor (6) in real time, and determining whether F is less than or equal to Fx, if not, returning to step S5, if yes, proceeding to step S8; S8, comparing the accumulated running time of the first variable frequency compressor (4) and the accumulated running time of the second variable frequency compressor (6) to obtain a first comparison result; S9, controlling the variable frequency compressor with a long cumulative running time to stop running according to the first comparison result; S10, controlling the remaining variable frequency compressors to continue to operate; S11, determine whether Tn is greater than or equal to the sum of Ts and T0, if not, return to step S10, if yes, control the variable frequency compressor to stop running.

6. A dual-system HVAC control method according to claim 5, characterized in that: After step S3, the method further includes the following steps: S12, if ΔT is less than T1, determine whether ΔT is greater than or equal to T2, if not, control the first variable frequency compressor (4) and the second variable frequency compressor (6) to maintain a standby state, if yes, proceed to step S13; S13, comparing the accumulated running time of the first variable frequency compressor (4) and the accumulated running time of the second variable frequency compressor (6) to obtain a second comparison result; S14, controlling the variable frequency compressor with the longest cumulative running time to maintain a standby state according to the second comparison result; S15, controlling the remaining variable frequency compressors to start running; S16, determine whether Tn is greater than or equal to the sum of Ts and T0, if not, return to step S15, if yes, control the variable frequency compressor to stop running.

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