Cold storage and discharge regulation and control method for central air conditioning system

Abstract

The invention discloses a cold storage and discharge regulation and control method for a central air-conditioning system, which comprises the following steps of: S100, creating a load and energy efficiency curve chart of a water chilling unit according to working data of the central air-conditioning system, and selecting a load value range D-G of the water chilling unit running at a high energy efficiency ratio according to the load and energy efficiency curve chart of the water chilling unit; and S200, a cold storage pool is arranged, and the load value of the water chilling unit is maintained between D and G through cold storage and cold release of the cold storage pool. While the energy efficiency ratio of the water chilling unit is increased, the use requirement for operating a single water chilling unit in the cold peak period is met, and the purposes of saving energy and reducing carbon are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of energy saving of air conditioning systems, and in particular to a cold storage and release control method for a central air conditioning system. Background Art

[0002] The central air-conditioning system is an air-conditioning solution for centralized cooling and heating, which is widely used in large places such as commercial buildings, hotels, hospitals, industrial facilities, etc. The central air-conditioning system includes a chilled water subsystem and a cooling water subsystem. The chilled water subsystem refers to the water system circulating between the chiller and the terminal equipment, with an inlet and outlet water temperature of 7-12°C, which is relatively low. It is used to transport the chilled water generated by the unit to the fan coil or air handling unit to achieve indoor cooling or heating; the cooling water system refers to the water system circulating between the unit and the outdoor heat dissipation equipment, with an inlet and outlet water temperature of 37-32°C, which is relatively high. It is responsible for taking away the heat generated by the chiller during the refrigeration process to maintain the normal operation of the unit.

[0003] The load of the central air-conditioning system is greatly affected by the external ambient temperature, especially in places where a large amount of outdoor fresh air is used. For example, at noon in summer, the solar radiation heat is the strongest and the outdoor temperature is the highest. At this time, the central air-conditioning cooling load is the largest. If the chiller is operated at the maximum load, the cooling capacity of a single chiller may be insufficient. If the operating load of the two chillers is low, the energy efficiency ratio will be low and electricity will be wasted. In addition, both high-load and low-load operations will affect the working units of the central air-conditioning system and reduce their service life. Summary of the invention

[0004] In view of the above technical problems in the related art, the present invention provides a cold storage and cooling release control method for a central air-conditioning system, which can solve the above problems.

[0005] To achieve the above technical objectives, the technical solution of the present invention is implemented as follows: A method for regulating and controlling cold storage and release for a central air conditioning system, comprising the following steps: S100, creating a chiller load and energy efficiency curve diagram based on the central air conditioning system working data, and selecting a load value range D to G for the chiller to operate at a high energy efficiency ratio based on the chiller load and energy efficiency curve diagram; S200, setting a cold storage tank, and maintaining the load value of the chiller between D and G by storing and releasing cold in the cold storage tank, wherein storing and releasing cold in the cold storage tank specifically includes the following steps: When the required cooling capacity of the chilled water subsystem is below the load value of a single chiller, the valves of the cold storage return water pipe and the cold storage water supply pipe are opened. The 7°C cold water produced by the chiller flows through the chilled water outlet main pipe of the chiller, and then flows into the cold storage coil in the cold storage tank through the cold storage water supply pipe. After cooling the medium in the cold storage tank, it flows back to the chilled water main return water pipe through the cold storage return water pipe. After being pressurized by the chilled water pump, it is cooled to 7°C by the chiller through the chiller evaporator inlet pipe. This cycle is repeated. When the temperature of the medium in the cold storage tank drops to t1 or the load of the chiller exceeds G, the valve on the cold storage return water pipe is closed. When the water inlet temperature of the chiller condenser exceeds 32°C or the operating load of the chiller exceeds G, the valves on the cooling return water pipe and the cooling water supply pipe are opened, and the low-temperature medium in the cold storage tank exchanges heat with the cooling coil. The water in the cooling coil is cooled and then flows back to the cooling water pump suction main pipe through the cooling water supply pipe. After mixing with the cooling water cooled by the cooling tower, it is pressurized by the cooling water pump and enters the chiller condenser. After absorbing the heat of the condenser, it flows back to the cold storage tank through the cooling return water pipe and is cooled by the cooling coil. This cycle is repeated. When the medium in the cold storage tank is heated to t2, the valve on the cooling water supply pipe is closed.

[0006] Furthermore, the chiller is a magnetic levitation chiller or a variable frequency chiller.

[0007] Furthermore, both the cooling water pump and the freezing water pump are variable frequency pumps.

[0008] Furthermore, the cold storage pool is a fire water pool located in the basement, the medium of the cold storage pool is clean water, and the medium of the cold storage pool does not contain cold storage coils and cooling coils.

[0009] Furthermore, the volume of the cold storage tank is V1, the immersed volume of the cold storage coil and the cooling coil is V2, and the rated capacity of the cold storage tank for fire water is V3, then V1>V2+V3.

[0010] Furthermore, one end of the cold storage return water pipe is connected to the air-conditioning chilled water main return water pipe at the front section of the air-conditioning chilled water pump water inlet main pipe, and an electric butterfly valve or an electric three-way valve is installed, and the other end is connected to the cold storage coil main return water collecting pipe of the cold storage tank; one end of the cold storage water supply pipe is connected to the air-conditioning chilled water main supply water pipe at the rear section of the air-conditioning chiller water outlet main pipe, and a static balancing valve is installed, and the other end is connected to the cold storage coil main supply water collecting pipe of the cold storage tank.

[0011] Furthermore, one end of the cooling return water pipe is connected to the rear section of the cooling water outlet main pipe of the air-conditioning chiller, and a static balancing valve is installed, and the other end is connected to the cooling coil main return water collecting pipe of the cold storage tank; one end of the cooling water supply pipe is connected to the front section of the cooling water pump inlet main pipe, and an electric butterfly valve or an electric three-way valve is installed, and the other end is connected to the cooling coil main supply water collecting pipe of the cold storage tank.

[0012] Furthermore, the value of D is 40%, the value of G is 90%, the value of t1 is 7°C, and the value of t2 is 28°C.

[0013] Beneficial effects of the present invention: While improving the energy efficiency ratio of the chiller, the present application meets the demand for operating a single chiller during the peak cooling period, thereby achieving the purpose of energy saving and carbon reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] The present invention is further described in detail below with reference to the accompanying drawings.

[0016] Figure 1 It is a structural diagram of a central air conditioning system connected to a cold storage tank according to an embodiment of the present invention; Figure 2 is a load and energy efficiency curve diagram of a chiller according to an embodiment of the present invention; Figure 3 1 is a simplified structural diagram of a cold storage tank according to an embodiment of the present invention.

[0017] In the figure: 1. Cold storage return water pipe; 2. Cold storage water supply pipe; 3. Cooling return water pipe; 4. Cooling supply pipe; 5. Cold storage tank; 6. Chiller; 7. Chilled water pump; 8. Cooling water pump; 9. Metal hose. DETAILED DESCRIPTION

[0018] The following will be combined with the accompanying 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 belong to the scope of protection of the present invention.

[0019] like Figures 1 to 3 As shown, according to the present invention, a method for regulating and controlling cold storage and release for a central air-conditioning system is disclosed, comprising the following steps: S100, create a chiller load and energy efficiency curve using the central air conditioning system working data (such as Figure 2 As shown, the load value range of the chiller is 40% to 90%, with a high energy efficiency ratio, COP>6.8), so the load value range of the chiller in high energy efficiency ratio operation is selected as 40% to 90% through the chiller load and energy efficiency curve; S200, setting a cold storage tank 5, and maintaining the load value of the chiller between 40% and 90% by storing and releasing cold in the cold storage tank 5, and storing and releasing cold in the cold storage tank 5 specifically includes the following steps: When the refrigeration capacity required by the chilled water subsystem is below 40% of the load value of a single chiller, the valves of the cold storage return pipe 1 and the cold storage water supply pipe 2 are opened, and the 7°C cold water produced by the chiller 6 flows through the chilled water outlet main pipe of the chiller, and then flows into the cold storage coil in the cold storage tank through the cold storage water supply pipe 2, cools the medium in the cold storage tank and then flows back to the chilled water main return pipe through the cold storage return pipe 1, and after being pressurized by the chilled water pump 7, it is cooled by the chiller to 7°C through the chiller evaporator inlet pipe, and the cycle is repeated. When the medium in the cold storage tank is cooled to 12°C (adjustable setting) or the load of the chiller exceeds 90%, the valve on the cold storage return pipe 1 is closed (the purpose of cold storage through the water tank is to increase the cooling load of the chiller to more than 40% when the chiller is running at low load, so as to improve the COP of the chiller, COP is the energy efficiency ratio); When the water inlet temperature of the chiller condenser exceeds 32°C or the chiller operating load exceeds 90%, the valves on the cooling return water pipe 3 and the cooling water supply pipe 4 are opened, and the low-temperature medium in the cold storage tank 5 exchanges heat with the cooling coil. After the water in the cooling coil is cooled, it flows back to the cooling water pump suction main pipe through the cooling water supply pipe 4, and after mixing with the cooling water cooled by the cooling tower, it is pressurized by the cooling water pump 8 and enters the chiller condenser. After absorbing the heat of the condenser, it flows back to the cold storage tank through the cooling return water pipe 3 and cools down through the cooling coil. This cycle repeats. When the medium in the cold storage tank is heated to 28°C (adjustable setting), the valve on the cooling water supply pipe 4 is closed. By releasing the coldness of the cold storage tank to the cooling water subsystem, the cooling water temperature entering the chiller condenser is reduced, and the power consumption of the chiller can be reduced.

[0020] The entire control method of the present application is controlled by the main controller of the central air-conditioning system. The cooling water temperature and the medium temperature in the cold storage tank can be identified by the temperature sensor and transmitted to the main controller. A flow meter can be installed in the cold water pipe to measure the water flow through the chiller in real time. The flow and temperature data are used in combination to calculate the chiller load and transmit it to the main controller.

[0021] Embodiment 1: In the present application, the chillers 6 include two, which are magnetic levitation chillers or variable frequency chillers. The cooling water pump 8 and the freezing water pump 7 are both variable frequency pumps. The variable frequency pump and the variable frequency chiller not only improve the energy utilization efficiency in the central air-conditioning system, but also improve the system's operating stability and comfort.

[0022] Embodiment 2: like Figure 1 As shown, one end of the cold storage return water pipe 1 is connected to the main return water pipe of the air-conditioning chilled water at the front section of the air-conditioning chilled water pump water inlet main pipe, and an electric butterfly valve or an electric three-way valve is installed, and the other end is connected to the main return water collecting pipe of the cold storage coil of the cold storage tank 5; one end of the cold storage water supply pipe 2 is connected to the main supply water pipe of the air-conditioning chilled water at the rear section of the air-conditioning chiller water outlet main pipe, and a static balancing valve is installed, and the other end is connected to the main supply water collecting pipe of the cold storage coil of the cold storage tank 5.

[0023] One end of the cooling return water pipe 3 is connected to the rear section of the cooling water outlet main pipe of the air-conditioning chiller and is installed with a static balancing valve, and the other end is connected to the cooling coil main return water collecting pipe of the cold storage tank 5; one end of the cooling water supply pipe 4 is connected to the front section of the cooling water pump inlet main pipe and is installed with an electric butterfly valve or an electric three-way valve, and the other end is connected to the cooling coil main supply water collecting pipe of the cold storage tank 5.

[0024] like Figure 3 As shown, a number of disc-shaped metal hoses 9 are immersed in the cold storage tank 5, a part of which is used as cold storage coils, and a part of which is used as cooling coils. Both ends of the metal hoses (water distribution pipes) used as cold storage coils and the metal hoses (water distribution pipes) used as cooling coils are gathered at one place (main water collecting pipe). The use of a multi-tube structure is beneficial to improving heat exchange efficiency.

[0025] Embodiment three: The structure of the central air conditioning system in this application is as follows Figure 1 As shown, it is used for high-rise buildings, including 3 underground floors and 21 above-ground floors, and is equipped with a complete fire-fighting system (fire pump room, fire water pool). The fire pump room and the fire water pool are both located on the third underground floor. In this application, a cold storage pool is not constructed separately, but an existing fire water pool is used for improvement, wherein the volume of the cold storage pool is V1, the immersion volume of the cold storage coil and the cooling coil is V2, and the rated capacity of the cold storage pool for fire-fighting water is V3, then V1>V2+V3, and further, the change of water temperature in the fire water pool during the cold storage and cooling stages will not cause the fire water to freeze, ensuring that the fire water pool is used for the cold storage pool without affecting its original fire-fighting function. In addition, it is located in the basement environment, so the environment is cool, which is conducive to the natural cooling of the fire water with a higher temperature after cooling, thereby saving energy.

[0026] Furthermore, in the basement environment of the present application, more than two fire water tanks are arranged as cold storage tanks. For example, when the chiller continues to operate at a high load, after one cold storage tank is saturated with cold, other cold storage tanks can be used to continue cooling, and the saturated cold storage tank can enter a natural cooling state.

[0027] Furthermore, the high-rise building can be used as an office building. When the office is not in use and the air conditioning system is not running at night, the night time can be fully utilized for natural cooling, thereby saving energy.

[0028] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for regulating and controlling cold storage and cooling for a central air conditioning system, characterized in that: The following steps are involved: S100, creating a chiller load and energy efficiency curve diagram based on the central air conditioning system working data, and selecting a load value range D to G for the chiller to operate at a high energy efficiency ratio based on the chiller load and energy efficiency curve diagram; S200, setting a cold storage tank, and maintaining the load value of the chiller between D and G by storing and releasing cold in the cold storage tank, wherein storing and releasing cold in the cold storage tank specifically includes the following steps: When the required cooling capacity of the chilled water subsystem is below the load value of a single chiller, the valves of the cold storage return pipe and the cold storage water supply pipe are opened. The 7°C cold water produced by the chiller flows through the chilled water outlet main pipe of the chiller and then flows into the cold storage coil in the cold storage tank through the cold storage water supply pipe. The medium in the cold storage tank is cooled down and then flows back to the chilled water main return pipe through the cold storage return pipe. After being pressurized by the chilled water pump, it is cooled down to 7°C by the chiller through the chiller evaporator inlet pipe. This cycle is repeated. When the medium in the cold storage tank is cooled down to t1 or the load of the chiller exceeds G, the valve on the cold storage return pipe is closed. When the water inlet temperature of the chiller condenser exceeds 32℃ or the operating load of the chiller exceeds G, open the valves on the cooling return water pipe and the cooling water supply pipe, and the low-temperature medium in the cold storage tank exchanges heat with the cooling coil. The water in the cooling coil is cooled and then flows back to the cooling water pump suction main pipe through the cooling water supply pipe. After mixing with the cooling water cooled by the cooling tower, it is pressurized by the cooling water pump and enters the chiller condenser. After absorbing the heat of the condenser, it flows back to the cold storage tank through the cooling return water pipe and is cooled by the cooling coil. This cycle is repeated. When the medium in the cold storage tank rises to t2, close the valve on the cooling water supply pipe.

2. A method for regulating and controlling cold storage and cooling for a central air conditioning system according to claim 1, characterized in that: The chiller is a magnetic levitation chiller or a variable frequency chiller.

3. A method for regulating and controlling cold storage and cooling for a central air conditioning system according to claim 1, characterized in that: Both cooling water pumps and chilled water pumps are variable frequency pumps.

4. The method for regulating and controlling cold storage and cooling release for a central air conditioning system according to claim 1, characterized in that: The cold storage tank is a fire water tank located in the basement. The medium of the cold storage tank is clean water. There are no cold storage coils and cooling coils immersed in the medium of the cold storage tank.

5. A method for regulating and controlling cold storage and cooling release for a central air conditioning system according to claim 4, characterized in that: The volume of the cold storage tank is V1, the immersed volume of the cold storage coil and the cooling coil is V2, and the rated capacity of the cold storage tank for fire water is V3, then V1>V2+V3.

6. A method for regulating and controlling cold storage and cooling for a central air conditioning system according to claim 1, characterized in that: One end of the cold storage return water pipe is connected to the main return water pipe of the air conditioner chilled water at the front section of the air conditioner chilled water pump water inlet main pipe, and an electric butterfly valve or an electric three-way valve is installed, and the other end is connected to the main return water collecting pipe of the cold storage coil of the cold storage tank; one end of the cold storage water supply pipe is connected to the main supply water pipe of the air conditioner chilled water at the rear section of the air conditioner chiller water outlet main pipe, and a static balancing valve is installed, and the other end is connected to the main supply water collecting pipe of the cold storage coil of the cold storage tank.

7. A method for regulating and controlling cold storage and cooling for a central air conditioning system according to claim 1, characterized in that: One end of the cooling return water pipe is connected to the rear section of the cooling water outlet main of the air-conditioning chiller and a static balancing valve is installed, and the other end is connected to the cooling coil main return water collecting pipe of the cold storage tank; one end of the cooling water supply pipe is connected to the front section of the cooling water pump inlet main and an electric butterfly valve or an electric three-way valve is installed, and the other end is connected to the cooling coil main supply water collecting pipe of the cold storage tank.

8. The method for regulating and controlling cold storage and cooling release for a central air conditioning system according to claim 1, characterized in that: The value of D is 40%, the value of G is 90%, the value of t1 is 7°C, and the value of t2 is 28°C.

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