Phase change energy storage refrigeration central air conditioner utilizing natural cooling

Abstract

The utility model provides a phase change energy storage refrigeration central air conditioner utilizing natural cooling. The phase change energy storage refrigeration central air conditioner comprises a refrigeration main unit, a phase change energy accumulator and a natural cooling system. A cold water outlet of the refrigeration main unit is connected with a first-stage cold water conveying pipeline through a cold-producing circulating water pump, a cooling capacity conveying variable-frequency pump is serially mounted in the pipeline, an outlet of the variable-frequency pump is connected with a user air supply system through a second-stage cold water conveying pipeline, and return water of the air supply system is connected with a water inlet of the refrigeration main unit; one end of the phase-change energy accumulator is connected with a pipeline between the cold-producing circulating water pump and the cooling capacity conveying variable-frequency pump, and the other end is connected with a return water conveying pipeline; the natural cooling system comprises a cooling tower and a heat exchanger, the cooling tower and the heat exchanger form a refrigerant circulation loop, and the heat exchanger and the phase change energy accumulator form a heating medium circulation loop. The phase change energy accumulator operates in the daytime to release the phase change latent heat energy of the phase change material for refrigeration, so that the system can meet the refrigeration demand load, the use energy consumption of the refrigerating unit in the daytime is reduced, the energy efficiency of system operation is effectively improved, and energy is saved.

Description

Technical Field

[0001] This utility model relates to the field of central air conditioning system technology, specifically to a phase change energy storage refrigeration central air conditioning system that utilizes natural cooling. Background Technology

[0002] Currently, traditional mechanical refrigeration technology is the mainstream cooling method for central air conditioning. It mainly achieves heat transfer through the cyclical operation of refrigeration units (including compressors, condensers, evaporators, and throttling devices). When cooling is needed, the mechanical refrigeration system is activated. Although it can meet the cooling needs in normal environments, it has significant drawbacks in specific application scenarios. For example, in areas with significant diurnal temperature differences (such as deserts and plateaus), the ambient temperature is low at night. Taking the Taklamakan Desert as an example, the nighttime temperature can drop below 5°C. These natural cooling resources are not effectively captured and utilized, resulting in the traditional mechanical refrigeration system still needing to activate the compressor and condenser for cooling when the ambient temperature is high during the day, forming a "double waste" of energy.

[0003] Natural cooling refers to the technology of utilizing low-temperature resources existing in the natural environment (such as low-temperature air at night, groundwater, soil chill, winter ice and snow) to provide cooling capacity for buildings, equipment, or systems through passive or active means. Its core is to reduce or replace the energy consumption of traditional mechanical refrigeration, and it is an important branch of green energy-saving technology.

[0004] Therefore, there is an urgent need to develop a new type of central air conditioning refrigeration system that can intelligently combine environmental cold sources with mechanical refrigeration, especially in areas with significant day-night temperature differences, to achieve a leap in energy utilization efficiency. Utility Model Content

[0005] This invention provides a phase change energy storage central air conditioner that utilizes natural cooling. It adds a natural cooling system to the existing refrigeration unit that uses electricity, and can switch and combine various working modes according to different usage conditions.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A phase change energy storage central air conditioning system utilizing natural cooling includes a refrigeration unit, a phase change energy storage device, and a natural cooling system. The chilled water outlet of the refrigeration unit is connected to a first-stage chilled water delivery pipeline via a chilled water circulation pump. A chilled water delivery variable frequency pump is also connected in series in the first-stage chilled water delivery pipeline. The outlet of the chilled water delivery variable frequency pump is then delivered to the user's air supply system via a second-stage chilled water delivery pipeline. The outlet of the air supply system is connected to a return water delivery pipeline, which is connected to the inlet of the refrigeration unit. One end of the phase change energy storage device is connected to the first-stage chilled water delivery pipeline between the chilled water circulation pump and the chilled water delivery variable frequency pump via a pipeline, and the other end of the phase change energy storage device is connected to the return water delivery pipeline via a pipeline.

[0008] The system will control the cooling capacity of the refrigeration unit, the flow rate of the cooling circulating water pump and the cooling capacity delivery variable frequency pump as needed to enable the phase change accumulator to store and release energy. Specifically, when the phase change accumulator is storing energy, the delivery capacity of the cooling capacity delivery variable frequency pump is reduced and / or the flow rate of the chilled water outlet of the refrigeration unit is increased, so that the water pressure in the first-stage chilled water delivery pipe is greater than that in the return water delivery pipe. The chilled water in the first-stage chilled water delivery pipe flows into the phase change accumulator through the pipe, causing the energy storage material in the phase change accumulator to produce phase change energy storage. The chilled water temperature rises and flows out of the phase change accumulator through the other end into the return water delivery pipe.

[0009] When the phase change accumulator releases stored energy, the delivery capacity of the cold energy transfer variable frequency pump is increased and / or the flow rate of the chilled water outlet of the chiller unit is reduced or even the chiller unit is shut down. This causes the water pressure in the return water transfer pipe to be greater than that in the first-stage chilled water transfer pipe. The water in the return water transfer pipe flows into the phase change accumulator through the pipe. The energy storage material in the phase change accumulator undergoes a phase change and releases stored energy, causing the return water to cool down. It then flows out of the phase change accumulator at the other end and enters the first-stage chilled water transfer pipe. After being pressurized by the cold energy transfer variable frequency pump, it enters the second-stage chilled water transfer pipe and is delivered to the user's air supply system.

[0010] The natural cooling system includes a cooling tower and a heat exchanger. The cooling tower is connected to the refrigerant input and output ends of the heat exchanger to form a refrigerant circulation loop. The heat exchanger's heat input and output ends are connected to a phase change accumulator to form a heat transfer circulation loop. When the ambient temperature is low, the condensate naturally cooled in the cooling tower is used as a refrigerant and exchanged with the return water in the phase change accumulator through the heat exchanger. This cools the return water in the phase change accumulator and sends it back to the phase change accumulator through the heat transfer output end, thereby triggering phase change condensation in the phase change accumulator to store cold for refrigeration.

[0011] The system will switch as needed (e.g., when the ambient temperature is low at night), controlling the cooling tower and heat exchanger to work together to enable the phase change accumulator to store and cool energy, as detailed below:

[0012] When the ambient temperature is low at night and the phase change accumulator has a storage and cooling requirement, the refrigeration unit is shut down and the natural cooling system is started. The cooling water in the cooling tower, cooled by the natural environment, flows into the heat exchanger through the refrigerant input end. At the same time, the return water in the phase change accumulator, which is fed in through the return water pipeline, flows into the heat exchanger through the heat medium input end. Through heat exchange between the cooling water and the return water, the temperature of the return water is reduced and flows into the phase change accumulator through the heat medium output end. This triggers the energy storage material in the phase change accumulator to undergo phase change and solidify for storage and cooling. After heat exchange with the return water, the temperature of the cooling water is increased and flows into the cooling tower through the refrigerant output end for natural cooling and circulation.

[0013] When daytime ambient temperatures rise and cooling is required, the phase change accumulator has already stored and cooled its energy overnight through the natural cooling system. Therefore, there is no need to start the main chiller unit. The phase change accumulator is set to release its stored energy, providing and meeting the cooling load demand. The phase change accumulator releases its stored energy, increasing the flow rate of the cooling capacity delivery inverter pump and / or reducing the flow rate at the chilled water outlet of the main chiller unit, or even shutting down the main chiller unit. This causes the water pressure in the return water delivery pipe to be higher than that in the first-stage chilled water delivery pipe. Water from the return water delivery pipe flows through the pipe into the phase change accumulator, where the energy storage material undergoes a phase change, releasing its stored energy and cooling the return water. The water then flows out of the phase change accumulator at the other end and enters the first-stage chilled water delivery pipe. After being pressurized by the cooling capacity delivery inverter pump, it enters the second-stage chilled water delivery pipe and is delivered to the user's air supply system.

[0014] Furthermore, two refrigeration units can be connected in series to form a refrigeration unit chain, and one or more refrigeration unit chains can be connected in parallel to form the refrigeration unit group.

[0015] Furthermore, the two refrigeration units in the refrigeration unit chain are connected in series, and are divided into a high-temperature refrigeration unit and a low-temperature refrigeration unit. Specifically: for the evaporator circuit, the return water supply pipeline is connected to the inlet of the evaporator circuit of the high-temperature refrigeration unit, the outlet of the evaporator circuit of the high-temperature refrigeration unit is connected to the inlet of the evaporator circuit of the low-temperature refrigeration unit, and the outlet of the evaporator circuit of the low-temperature refrigeration unit is connected to the cooling circulating water pump; for the condenser circuit, the cooling tower is connected to the cooling water pump via a cooling water pipe, the outlet of the cooling water pump is connected to the inlet of the condenser circuit of the low-temperature refrigeration unit via a cooling water pipe, the outlet of the condenser circuit of the low-temperature refrigeration unit is connected to the inlet of the condenser circuit of the high-temperature refrigeration unit, and the outlet of the condenser circuit of the high-temperature refrigeration unit is connected to the cooling tower.

[0016] Furthermore, the cooling water pump is provided in one or more sets, which are connected in parallel. Their inlets are connected in parallel to the outlet of the cooling tower, and their outlets are connected in parallel to the inlet of the condenser circuit of the low-temperature refrigeration unit.

[0017] Furthermore, the outlet of the cooling water pump is equipped with a water distribution valve, which is connected to the water inlet of the condenser circuit of the low-temperature refrigeration unit and the refrigerant input end of the heat exchanger.

[0018] Furthermore, the cooling tower is equipped with indoor temperature sensors and outdoor temperature sensors on its inner and outer sides, respectively.

[0019] Furthermore, it also includes a solar thermal collector system, wherein the refrigeration unit further includes a solar-powered refrigeration unit chain formed by connecting an electric refrigeration unit and an absorption refrigeration unit in series, the heat energy input end of the absorption refrigeration unit is connected to the heating end of the solar thermal collector system; two electric refrigeration main units are connected in series to form an electric refrigeration unit chain; the refrigeration unit is composed of at least one solar-powered refrigeration unit chain and one electric refrigeration unit chain connected in parallel.

[0020] Furthermore, the solar thermal system includes at least a solar collector tube, an oil tank, and a heat storage tank connected in series. The heat medium outlet end of the solar collector tube is connected to the oil tank, the oil tank is connected to the high-temperature input end of the heat storage tank, the high-temperature output end of the heat storage tank is the heating end connected to the heat energy input end in the heating circuit of the absorption chiller, the output end in the heating circuit of the absorption chiller is connected to the low-temperature input end of the heat storage tank, and the low-temperature inlet and outlet ends of the heat storage tank are connected to the heat medium inlet end of the solar collector tube.

[0021] The operating strategies for solar-powered and electric-powered chiller chains within the chiller unit system include:

[0022] When there is sufficient sunlight, the solar-powered chiller unit starts to cool and output chilled water.

[0023] When there is no sun, if the central air conditioning system needs to cool, the electric chiller unit chain will start cooling and output chilled water; if the power supply cost is low, the electric chiller unit chain will start cooling and output chilled water, and the phase change accumulator will switch to energy storage mode.

[0024] The system's control strategies for storing and releasing energy in the phase change accumulator include:

[0025] The energy storage strategy involves the following steps: When the cooling demand load is low and there is sufficient sunlight, the solar-powered chiller chain starts cooling and sets the phase change energy storage device to operate in energy storage mode, storing the cooling capacity generated by the chiller unit in the phase change energy storage device; when there is no sunlight, the cooling demand load is low, and the power supply cost is low, the electric chiller chain starts cooling and sets the phase change energy storage device to operate in energy storage mode, storing the cooling capacity generated by the chiller unit in the phase change energy storage device.

[0026] The energy storage release strategy involves the following steps: When the cooling demand load is high and exceeds the load generated by the main chiller unit, and there is sufficient sunlight, the solar-powered chiller chain starts cooling and sets the phase change energy storage device to operate in the energy storage release mode, enabling the system to meet the cooling demand load; when the cooling demand load is high and exceeds the load generated by the main chiller unit, and there is no sunlight, the electric chiller chain starts cooling and sets the phase change energy storage device to operate in the energy storage release mode, enabling the system to meet the cooling demand load.

[0027] Compared with existing technologies, the beneficial effects of this utility model are as follows: By cooperating with the cooling tower, heat exchanger, and phase change energy storage device, the cooling water in the cooling tower is naturally cooled to about 6°C at night when the temperature is low, using the ambient temperature (e.g., below 5°C). At this time, if the phase change energy storage device has energy storage needs, the return water (e.g., about 10°C) supplied by the air supply system in the phase change energy storage device is heat exchanged with the cooling water through the heat exchanger, reducing the temperature of the return water from 10°C to 8°C. Then, it is transported to the phase change energy storage device through the heat medium output end of the heat exchanger to trigger the phase change material to solidify and store energy. This allows the phase change energy storage device to release stored energy for cooling during the daytime, enabling the system to meet the cooling load demand, reducing the energy consumption of the refrigeration unit, thereby effectively improving the energy efficiency of the system operation and saving energy. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present utility model;

[0029] Figure 2 This is a schematic diagram of the structure of Embodiment 2 of this utility model. Detailed Implementation

[0030] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0031] It should be noted that when a component / part is referred to as being "set on" another component / part, it can be directly set on the other component / part or there may be an intervening component / part. When a component / part is referred to as being "connected / linked" to another component / part, it can be directly connected / linked to the other component / part or there may be an intervening component / part. The term "connected / linked" as used herein can include electrical and / or mechanical physical connections / links. The term "including / comprises" as used herein means the presence of a feature, step, or component / part, but does not exclude the presence or addition of one or more other features, steps, or components / parts. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] like Figure 1 The illustration shows a first embodiment of this utility model: a phase change energy storage central air conditioning system utilizing natural cooling, comprising a refrigeration unit, a phase change energy storage device, and a natural cooling system. The refrigeration unit can be an existing central air conditioning chiller, such as a piston, screw, or centrifugal type. The phase change energy storage device consists of numerous phase change heat storage plates filled with eutectic salt cold storage material. The heat storage plates also have channels for cold water flow, which exchanges heat with the heat storage plates, enabling the eutectic salt cold storage material to undergo phase change to complete the function of energy storage or release.

[0033] The chilled water outlet of the refrigeration unit is connected to the first-stage chilled water delivery pipeline via a chilled water circulation pump. A chilled water delivery variable frequency pump is also connected in series in the first-stage chilled water delivery pipeline. The outlet of the chilled water delivery variable frequency pump is then delivered to the user's air supply system via a second-stage chilled water delivery pipeline. The outlet of the air supply system is connected to the return water delivery pipeline, which is connected to the inlet of the refrigeration unit. One end of the phase change accumulator is connected to the first-stage chilled water delivery pipeline between the chilled water circulation pump and the chilled water delivery variable frequency pump via a pipeline, and the other end of the phase change accumulator is connected to the return water delivery pipeline via a pipeline. The typical operating mode of the refrigeration unit is to adjust the output chilled capacity according to the load change. Therefore, when the load is low, the cooling efficiency (COP) of the refrigeration unit will decrease rapidly. To maintain efficient operation of the refrigeration unit under varying load conditions, this system incorporates a phase change energy storage device (PCA) to store and release energy. The refrigeration unit operates at its highest COP (Coefficient of Performance). If the cooling capacity exceeds the load demand, the PCA stores energy; conversely, if the cooling capacity falls short, the PCA releases stored energy to supplement the insufficient cooling capacity. Users can formulate operating strategies for the refrigeration unit based on normal usage statistics, ensuring efficient operation with the PCA and effectively improving system energy efficiency, saving 40%-70% or more compared to existing central air conditioning systems. Furthermore, users can continue to operate the refrigeration unit efficiently during off-peak hours when electricity is cheaper, storing cooling capacity in the PCA and releasing it during the day, further reducing operating electricity costs.

[0034] Preferably, in order to effectively utilize the low nighttime ambient temperatures in environments such as deserts and plateaus (taking the Taklamakan Desert as an example, where nighttime temperatures can drop below 5°C), the applicant converts the natural cooling generated by the ambient temperature into refrigeration capacity stored in a phase change energy storage unit. This allows the main refrigeration unit to be shut down, further reducing operating electricity costs. The natural cooling system includes a cooling tower and a heat exchanger. The cooling tower is connected to the refrigerant input and output ends of the heat exchanger to form a refrigerant circulation loop. The heat exchanger's heat input and output ends are connected to the phase change energy storage unit to form a heat transfer circulation loop. At night, the condensate naturally cooled in the cooling tower is used as a refrigerant and exchanged with the return water in the phase change energy storage unit through the heat exchanger. This cools the return water in the phase change energy storage unit and sends it back to the unit via the heat transfer output end, triggering a phase change and solidification process in the phase change energy storage unit to prepare for refrigeration. Specifically:

[0035] In low-temperature nighttime scenarios, the cooling water in the cooling tower is naturally cooled to around 6°C using the ambient temperature (e.g., below 5°C). If the phase change accumulator (PCA) requires energy storage, the return water (around 10°C) supplied by the air supply system is transported through the heat medium input to the heat exchanger (e.g., shell-and-tube heat exchanger, plate heat exchanger, or tubular heat exchanger). Meanwhile, the cooling water from the cooling tower is supplied through the refrigerant input to the heat exchanger, allowing the return water and cooling water to exchange heat, lowering the return water temperature from 10°C to 8°C. The returned water is then transported through the heat medium output to the PCA to trigger phase change material solidification and energy storage. This allows the PCA to release stored energy for cooling during the day, enabling the system to meet cooling load demands. This eliminates the need to start additional refrigeration units to generate cooling capacity for the PCA, reducing the energy consumption of the refrigeration units and effectively improving system efficiency, saving energy, and further reducing electricity costs.

[0036] The cooling water, after undergoing heat exchange in the heat exchanger (the cooling water temperature rises from 6°C to 8°C), is transported to the cooling tower through the refrigerant outlet. It is then recycled to the ambient temperature (such as below 5°C) to naturally cool the cooling water in the cooling tower to around 6°C, thus realizing the recycling of the natural cooling system.

[0037] To facilitate system control and switching between the natural cooling system and the refrigeration unit, the outlet of the cooling water pump is equipped with a water distribution valve. This valve is connected to both the inlet of the condenser circuit of the low-temperature refrigeration unit and the refrigerant input of the heat exchanger. When the natural cooling system needs to be operated at night, the water distribution valve is controlled to close the inlet of the condenser circuit of the low-temperature refrigeration unit and open the refrigerant input of the heat exchanger. This allows the cooling water in the cooling tower to flow into the heat exchanger and exchange heat with the return water in the phase change accumulator for cooling, thus achieving intelligent distribution of cooling water in the cooling tower.

[0038] Furthermore, the cooling tower is equipped with indoor and outdoor temperature sensors on its inner and outer sides, respectively. When the outdoor temperature sensor detects a high outdoor temperature, and the cooling tower cannot cool to the corresponding temperature naturally, the water distribution valve is controlled to allocate more cooling water to the condenser of the low-temperature refrigeration unit. Forced cooling is then achieved through compressor circulation, enabling the refrigeration unit to operate. When the outdoor temperature sensor detects a low outdoor temperature, and the cooling tower can efficiently cool the cooling water using natural cooling, the water distribution valve directs the naturally cooled cooling water to the refrigerant side of the heat exchanger. The cooling water then exchanges heat with the return water in the phase change accumulator, reducing the energy consumption of the refrigeration unit. The indoor temperature sensor is used to detect and monitor the temperature of the cooling water inside the cooling tower to ensure that the cooling water can properly exchange heat with the return water in the phase change accumulator.

[0039] Secondly, the system will control the cooling capacity of the refrigeration unit, the flow rate of the cooling circulating water pump, and the cooling capacity delivery variable frequency pump as needed to enable the phase change accumulator to store and release energy. The specific operation process is as follows:

[0040] When a phase change accumulator stores energy, one scenario occurs when the cooling capacity required by the user decreases, such as a reduction in the number of users in the air supply system or a decrease in the load on the air supply system due to a drop in ambient temperature. In this case, the delivery capacity of the variable frequency pump for cooling capacity delivery will also decrease accordingly. Another scenario is when the number of operating chillers in the refrigeration unit is actively increased, and more cooling circulating water pumps are turned on to increase the output of the refrigeration unit. In both of these situations, the water pressure in the first-stage chilled water delivery pipe is greater than that in the return water delivery pipe. The chilled water in the first-stage chilled water delivery pipe flows into the phase change accumulator, causing the energy storage material in the phase change accumulator to undergo phase change energy storage. After the phase change energy storage is completed, the chilled water temperature rises and flows out of the phase change accumulator at the other end into the return water delivery pipe, where it mixes with the return water from the air supply system and flows back to the inlet of the evaporator of the refrigeration unit.

[0041] When a phase change accumulator releases its stored energy, one scenario is a sudden increase in the number of users in the air supply system, while the cooling capacity of the chiller unit cannot meet the demand. Another scenario is that the phase change accumulator has sufficient stored energy to meet the supply, and the chiller unit has been completely shut down. In this case, the water pressure in the return water delivery pipe is greater than that in the first-stage chilled water delivery pipe. The water in the return water delivery pipe flows through the pipe into the phase change accumulator, where the energy storage material undergoes a phase change, releasing the stored energy and cooling the return water. The water then flows out of the phase change accumulator at the other end and enters the first-stage chilled water delivery pipe. After being pressurized by the variable frequency pump, the water then enters the second-stage chilled water delivery pipe and is delivered to the user's air supply system.

[0042] As can be seen from the above working process of energy storage and release, the overall design of the phase change accumulator is very simple and efficient. It only requires the coordination of the flow rate or working pressure of the cooling circulating water pump and the cooling capacity delivery frequency pump to realize the phase change accumulator working in different working states of energy storage or energy release. The simplified design and the reduction of required control valves can make the system operation more stable and reliable, reduce the occurrence of failures, and thus reduce the maintenance cost of system operation.

[0043] To further improve the energy efficiency of the refrigeration unit, this utility model preferentially uses two refrigeration units connected in series to form a refrigeration unit chain, and one or more refrigeration unit chains are connected in parallel to form the refrigeration unit group. Specifically:

[0044] The two refrigeration units in the refrigeration unit chain are connected in series, and are divided into a high-temperature refrigeration unit and a low-temperature refrigeration unit.

[0045] For the evaporator circuit, the return water supply line is connected to the inlet of the evaporator circuit of the high-temperature refrigeration unit, the outlet of the evaporator circuit of the high-temperature refrigeration unit is connected to the inlet of the evaporator circuit of the low-temperature refrigeration unit, and the outlet of the evaporator circuit of the low-temperature refrigeration unit is connected to the chilled water pump. Similarly, one or more chilled water pumps are provided, connected in parallel. Their inlets are connected in parallel to the total chilled water outlet of the refrigeration unit, and their outlets are connected in parallel to the first-stage chilled water supply line. In other words, the number of chilled water pumps that are turned on is determined solely by the cooling capacity required and is independent of the refrigeration unit.

[0046] For the condenser circuit, the cooling tower is connected to the cooling water pump via cooling water pipes. The outlet of the cooling water pump is connected to the inlet of the condenser circuit of the low-temperature refrigeration unit via cooling water pipes. The outlet of the condenser circuit of the low-temperature refrigeration unit is connected to the inlet of the condenser circuit of the high-temperature refrigeration unit, and the outlet of the condenser circuit of the high-temperature refrigeration unit is connected to the cooling tower. Similarly, one or more cooling water pumps are provided, connected in parallel. Their inlets are connected in parallel to the outlet of the cooling tower, and their outlets are connected in parallel to the inlet of the condenser circuit of the low-temperature refrigeration unit.

[0047] like Figure 2 The illustration shows a second embodiment of this utility model, which also includes a solar thermal collector system. The refrigeration unit further includes a solar-powered refrigeration unit chain formed by connecting an electric refrigeration unit and an absorption refrigeration unit in series. The heat input end of the absorption refrigeration unit is connected to the heating end of the solar thermal collector system. Two electric refrigeration main units are connected in series to form an electric refrigeration unit chain. The refrigeration unit is composed of at least one solar-powered refrigeration unit chain and one electric refrigeration unit chain connected in parallel.

[0048] Using solar-powered direct-flow internal focusing heat collectors, the system outputs an average of approximately 200°C of hot kerosene in summer, sufficient to power a dual-effect lithium bromide absorption chiller. In winter, it outputs an average of approximately 95°C of medium-temperature hot kerosene, which, through heat exchange plates, can provide 65°C hot water and the heat required for winter heating throughout the year. During periods of abundant sunshine in winter, the remaining high-temperature heat energy of the hot kerosene is stored in a kerosene storage tank for use at night and in the following day. In summer, during sunny periods, solar energy combined with the lithium bromide absorption chiller lowers the temperature of the central air conditioning chilled water from 16°C to 11°C. The chilled water is then transferred to an electric chiller to further lower the temperature from 11°C to 6°C, before being pressurized through a secondary water system and delivered to air handling units throughout the building. When there are no solar-powered hours on summer nights, and the air conditioning usage of large buildings is significantly reduced, only the electric cooling units need to be turned on. Using the most affordable peak-valley electricity prices, the lowest ambient temperature of the water tower, and the highest efficiency operating point of the centrifugal chillers, cooling is achieved. Besides meeting the cooling load of the large building at that time, the remaining cooling capacity is stored in a +8°C phase-change energy storage system for use during the next day's peak hours. The introduction of high-temperature solar direct-flow internal focusing collector technology and dual-effect absorption chiller units is believed to completely solve the problem of high energy consumption and reduced carbon emissions from central air conditioning systems for producing chilled and hot water and for heating in large buildings throughout the year. This can reduce average annual energy consumption (including electricity and natural gas) by more than 50%.

[0049] The aforementioned solar thermal system includes at least solar collector tubes, an oil tank, and a heat storage tank connected in series. The solar collector tubes collect solar energy to heat kerosene, the heat transfer medium. The outlet end of the solar collector tubes is connected to the oil tank, which is connected to the high-temperature input end of the heat storage tank to store the heat from the high-temperature kerosene. When the absorption chiller is operating, the heat storage tank supplies the high-temperature kerosene to the absorption chiller's heating circuit, driving the chiller to perform cooling operations. The kerosene is then further cooled by the absorption chiller's electrical energy and supplied to the air conditioning system or stored by a phase-change energy accumulator. The kerosene is then transported back to the heat storage tank for preheating before being sent to the solar collector tubes for further heating, forming a cycle.

[0050] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A phase change energy storage refrigeration central air conditioner using natural cooling, characterized by, The system includes a refrigeration unit, a phase change accumulator, and a natural cooling system. The chilled water outlet of the refrigeration unit is connected to a first-stage chilled water delivery pipeline via a cooling water circulation pump. A cooling capacity delivery variable frequency pump is also connected in series in the first-stage chilled water delivery pipeline. The outlet of the cooling capacity delivery variable frequency pump is then delivered to the user's air supply system via a second-stage chilled water delivery pipeline. The outlet of the air supply system is connected to a return water delivery pipeline, which is connected to the inlet of the refrigeration unit. One end of the phase change accumulator is connected to the first-stage chilled water delivery pipeline between the cooling water circulation pump and the cooling capacity delivery variable frequency pump via a pipeline, and the other end of the phase change accumulator is connected to the return water delivery pipeline via a pipeline. The natural cooling system includes a cooling tower and a heat exchanger. The cooling tower is connected to the refrigerant input and refrigerant output of the heat exchanger to form a refrigerant circulation loop. The heat exchanger's heat input and heat output are connected to a phase change energy storage device to form a heat medium circulation loop.

2. The phase change energy storage refrigeration central air conditioner using natural cooling according to claim 1, characterized in that, Two refrigeration units are connected in series to form a refrigeration unit chain, and one or more refrigeration unit chains are connected in parallel to form the refrigeration unit group.

3. The phase change energy storage refrigeration central air conditioner using natural cooling according to claim 2, characterized in that, The two refrigeration units in the refrigeration unit chain are connected in series, and are divided into a high-temperature refrigeration unit and a low-temperature refrigeration unit. Specifically: for the evaporator circuit, the return water supply pipeline is connected to the inlet of the evaporator circuit of the high-temperature refrigeration unit, the outlet of the evaporator circuit of the high-temperature refrigeration unit is connected to the inlet of the evaporator circuit of the low-temperature refrigeration unit, and the outlet of the evaporator circuit of the low-temperature refrigeration unit is connected to the cooling circulating water pump; for the condenser circuit, the cooling tower is connected to the cooling water pump via a cooling water pipe, the outlet of the cooling water pump is connected to the inlet of the condenser circuit of the low-temperature refrigeration unit via a cooling water pipe, the outlet of the condenser circuit of the low-temperature refrigeration unit is connected to the inlet of the condenser circuit of the high-temperature refrigeration unit, and the outlet of the condenser circuit of the high-temperature refrigeration unit is connected to the cooling tower.

4. The phase change material energy storage cooling central air conditioner using natural cooling according to claim 3, characterized in that, The cooling water pump is provided in one or more sets, and the cooling water pumps are connected in parallel. Their inlets are connected in parallel to the outlet of the cooling tower, and their outlets are connected in parallel to the inlet of the condenser circuit of the low-temperature refrigeration unit.

5. The phase change material energy storage cooling central air conditioner using natural cooling according to claim 3, characterized in that, The outlet of the cooling water pump is equipped with a water distribution valve, which is connected to the water inlet of the condenser circuit of the low-temperature refrigeration unit and the refrigerant input terminal of the heat exchanger.

6. The phase change energy storage refrigeration central air conditioner using natural cooling according to claim 1, characterized in that, The cooling tower is equipped with indoor temperature sensors and outdoor temperature sensors on its inner and outer sides, respectively.

7. The phase change material energy storage cooling central air conditioner using natural cooling according to claim 2, characterized in that, It also includes a solar thermal collector system, wherein the refrigeration unit further includes a solar-type refrigeration unit chain formed by connecting an electric refrigeration unit and an absorption refrigeration unit in series, wherein the heat energy input end of the absorption refrigeration unit is connected to the heat supply end of the solar thermal collector system; two electric refrigeration main units are connected in series to form an electric refrigeration unit chain; the refrigeration unit is composed of at least one solar-type refrigeration unit chain and one electric refrigeration unit chain connected in parallel.

8. The phase change energy storage refrigeration central air conditioner using natural cooling according to claim 7, characterized in that, The solar thermal collector system includes at least a solar collector tube, an oil tank, and a heat storage tank connected in series. The heat medium outlet end of the solar collector tube is connected to the oil tank, the oil tank is connected to the high-temperature input end of the heat storage tank, the high-temperature output end of the heat storage tank is the heating end and is connected to the heat energy input end in the heating circuit of the absorption chiller, the output end in the heating circuit of the absorption chiller is connected to the low-temperature input end of the heat storage tank, and the low-temperature inlet and outlet ends of the heat storage tank are connected to the heat medium inlet end of the solar collector tube.

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