Natural cold energy storage water chilling unit and energy-saving temperature control method

Abstract

The invention discloses a natural cold energy storage water chilling unit and an energy-saving temperature control method, and relates to the technical field of energy storage and temperature control, the unit comprises a water system and a refrigerating system, the main structure of the water system is that return water on the tail end battery pack side is connected to a water pump inlet, and a water pump outlet, a dry cooler and a first inlet of a three-way valve are sequentially communicated to form a first branch; the outlet of the water pump is sequentially communicated with the heater, the heat release passage of the heat exchanger and the second inlet of the three-way valve to form a second branch; an outlet of the three-way valve serves as a water supply port of the tail end battery pack side; the refrigerating system is connected with a heat-absorbing passage of the heat exchanger. The energy storage temperature control equipment can stably and reliably operate in the application process, natural cold and heat sources can be preferentially utilized, high efficiency and energy conservation are achieved, flow distribution of the secondary refrigerant is adjusted through the three-way valve, and accurate temperature control operation is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage temperature control, and particularly relates to a natural cooling energy storage water chiller and an energy-saving temperature control method. Background Art

[0002] In recent years, with the continuous development of the energy storage industry and the drafting and release of relevant standards for the energy storage temperature control field, the market has higher and higher requirements for the energy storage temperature control field. It is mainly reflected in aspects such as reliable operation, precise temperature control, and high energy efficiency. Compared with other air-conditioning refrigeration fields, the outdoor application scenarios of energy storage temperature control equipment are more complex, and the operation reliability of equipment in harsh and complex application scenarios is particularly important. In order to respond to the national strategy and relevant policies and achieve the goal of carbon peak and carbon neutrality as soon as possible, high energy efficiency is the development trend of the entire industry, and it is urgent to improve the energy-saving and temperature control effects of existing energy storage temperature control equipment. Summary of the Invention

[0003] Based on the above problems, the purpose of the present invention is to provide a natural cooling energy storage water chiller and an energy-saving temperature control method, which can achieve stable, reliable, high energy efficiency, and precise temperature control operation of energy storage temperature control equipment during application.

[0004] The technical solution adopted by the present invention is a natural cooling energy storage water chiller, which includes a water system and a refrigeration system, wherein:

[0005] The water system includes an expansion tank, a water pump, a heater, a heat exchanger, a dry cooler, and a three-way valve;

[0006] The return water on the side of the end battery pack is connected to the inlet of the water pump. The outlet of the water pump, the dry cooler, and the first inlet of the three-way valve are sequentially connected to form a first branch path; the outlet of the water pump is also sequentially connected to the heater, the heat release path of the heat exchanger, and the second inlet of the three-way valve to form a second branch path; the outlet of the three-way valve serves as the water supply port on the side of the end battery pack; the three-way valve is equipped with a water valve actuator, and the water valve actuator is used to control the opening degree of the three-way valve through an analog electrical signal, thereby adjusting the coolant flow rate of the first branch path and the second branch path, or opening and closing the first branch path and the second branch path; the expansion tank is arranged at the inlet of the water pump;

[0007] A return water temperature sensor and a return water pressure sensor are also arranged at the inlet of the water pump, and a water supply pressure sensor and a water supply temperature sensor are also arranged at the outlet of the water pump;

[0008] In specific implementation, according to the requirements of the client, the control can be switched between controlling according to the water supply temperature or the return water temperature. In most cases, it is controlled according to the water supply temperature; in addition, when controlling according to the water supply temperature, if the water supply temperature sensor fails, it can be automatically switched to controlling according to the return water temperature;

[0009] The refrigeration system is connected to the heat absorption path of the heat exchanger.

[0010] Further, the water pump is a variable-frequency water pump and can adjust the rotation speed according to requirements.

[0011] Further, the heater is of a pipe-type heating tube type and can only be turned on and off according to requirements, and the power output cannot be adjusted.

[0012] Further, the heat exchanger is a plate heat exchanger.

[0013] Further, the refrigeration system includes a compressor, a throttling element, a dryer filter, a condensation heat exchanger, and a cooling fan;

[0014] The outlet of the compressor, the condensation heat exchanger, the dryer filter, the throttling element, the heat absorption path of the heat exchanger and the inlet of the compressor are connected in sequence;

[0015] In specific implementation, an exhaust temperature sensor and an exhaust pressure sensor are further arranged at the outlet of the compressor, and a suction temperature sensor and a suction pressure sensor are further arranged at the inlet of the compressor.

[0016] The compressor and the heater cannot be turned on simultaneously.

[0017] Furthermore, the compressor is a variable-frequency compressor and can adjust the rotation speed according to requirements, and the throttling element is an electronic expansion valve.

[0018] Furthermore, the dry cooler is arranged below the condensation heat exchanger, and the dry cooler and the condensation heat exchanger share the cooling fan. Outdoor air first passes through the dry cooler and then through the condensation heat exchanger, and is sent out under the forced convection of the cooling fan.

[0019] The present invention also provides an energy-saving temperature control method for a natural cold energy storage chiller, which is applied to the above-mentioned natural cold energy storage chiller, and the method includes:

[0020] Preset temperature thresholds T1, T2, T3, and T3 < T2 < T1;

[0021] Judge the ambient temperature t, where the ambient temperature t is the value from the ambient temperature sensor, and the ambient temperature sensor is arranged at the return air outlet of the unit;

[0022] If t ≥ T1, the unit operates in the extreme high temperature condition. During refrigeration, the refrigeration system starts, and at the same time, the opening degree of the three-way valve is adjusted to open both the first branch and the second branch of the water system;

[0023] If T2 < t ≤ T1, the unit operates under normal temperature conditions. During refrigeration, the refrigeration system starts, and at the same time, the three-way valve is adjusted to shut off the first branch and open the second branch. During heating, the refrigeration system is closed, and at the same time, the opening of the three-way valve is adjusted to open both the first branch and the second branch, and the opening of the three-way valve is adjusted according to the supply water temperature measured by the supply water temperature sensor or the return water temperature measured by the return water temperature sensor to adjust the coolant flow rate in the first branch.

[0024] If T3 < t ≤ T2, the unit operates under low temperature conditions. During refrigeration, the refrigeration system is first closed, the opening of the three-way valve is adjusted to open the first branch of the water system, and the opening of the three-way valve is adjusted according to the supply water temperature measured by the supply water temperature sensor or the return water temperature measured by the return water temperature sensor to adjust the coolant flow rate in the first branch. During heating, the refrigeration system is closed, the opening of the three-way valve is adjusted to open both the first branch and the second branch, the heater is turned on at the same time, and the opening of the three-way valve is adjusted so that the cooling capacity provided by the dry cooler through the first branch is less than the heating capacity provided by the heater through the second branch.

[0025] Furthermore, if T2 < t ≤ T1, during heating, when the coolant flow rate in the first branch increases to the limit and the heating capacity of the unit still does not meet the requirements of the terminal battery pack, specifically, after the unit operates stably for a period of time such as 10 minutes and the supply water temperature or the return water temperature continues to decrease, it can be determined that the heating capacity of the unit does not meet the requirements of the terminal battery pack, and the heater on the second branch is turned on.

[0026] Furthermore, if T3 < t ≤ T2, during refrigeration, when the coolant flow rate in the first branch increases to the limit and still does not meet the refrigeration requirements of the terminal battery pack, specifically, after the unit operates stably for a period of time such as 10 minutes and the supply water temperature or the return water temperature continues to rise, it can be determined that the refrigeration capacity of the unit does not meet the requirements of the terminal battery pack, the opening of the three-way valve is adjusted to open the second branch, and the refrigeration system is started at the same time.

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

[0028] When the ambient temperature is high, the unit operates under the extreme high temperature condition, both the first branch and the second branch of the water system are opened, and the coolant exchanges heat with the outdoor high temperature air in the dry cooler to reduce the inlet air temperature of the condensation heat exchanger of the refrigeration system, improve the operation stability and refrigeration efficiency of the chiller under the extreme high ambient temperature, and have good reliability;

[0029] When the ambient temperature is at normal temperature, the unit operates in the normal temperature condition. During refrigeration, the first branch circuit is shut off and the second branch circuit is opened. All the secondary refrigerant passes through the second branch circuit and exchanges heat with the low-temperature and low-pressure refrigerant in the heat exchanger, and its temperature drops to achieve the refrigeration purpose. During heating, both the first branch circuit and the second branch circuit are opened. The flow rate of the secondary refrigerant in the first branch circuit is adjusted according to the outlet water temperature, so as to make the heating capacity of the unit adjustable, reduce the fluctuation of the outlet water temperature, achieve precise temperature control, have good stability, give priority to using natural heat sources, effectively reduce the opening frequency and time of the heater, and have good energy-saving performance.

[0030] When the ambient temperature is low, the unit operates in the low-temperature condition. During refrigeration of the unit, the first branch circuit is opened, giving priority to using natural cold sources, effectively reducing the opening frequency and time of the compressor in the refrigeration system, and having good energy-saving performance. During heating, both the first branch circuit and the second branch circuit are opened, the heater is turned on, and the net heating capacity of the unit is adjusted by adjusting the flow rate of the secondary refrigerant in the first branch circuit, so as to make the heating capacity of the unit adjustable, achieve precise temperature control, and have good stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic structural diagram of the unit in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0033] Embodiment 1

[0034] Figure 1 A specific embodiment of the natural cold energy storage chiller of the present invention is shown, including a water system and a refrigeration system, wherein:

[0035] The water system includes an expansion tank 3, a water pump 4, a heater 5, a heat exchanger 6, a dry cooler 7, and a three-way valve 8;

[0036] The return water on the side of the terminal battery pack is connected to the inlet of the water pump 4. The outlet of the water pump 4, the dry cooler 7, and the first inlet of the three-way valve 8 are sequentially connected to form a first branch circuit 16. The outlet of the water pump 4 is also sequentially connected to the heater 5, the heat release path of the heat exchanger 6, and the second inlet of the three-way valve 8 to form a second branch circuit 17. The outlet of the three-way valve 8 serves as the water supply port on the side of the terminal battery pack; the three-way valve 8 is equipped with a water valve actuator, and the water valve actuator is used to control the opening degree of the three-way valve 8 through an analog electrical signal; the expansion tank 3 is arranged at the inlet of the water pump 4;

[0037] A return water temperature sensor 1 and a return water pressure sensor 2 are also arranged at the inlet of the water pump 4, and a water supply pressure sensor 9 and a water supply temperature sensor 10 are also arranged at the outlet of the water pump 4;

[0038] The refrigeration system includes a compressor 11, a throttling element 12, a dryer filter 13, a condensation heat exchanger 14, and a cooling fan 15.

[0039] The outlet of the compressor 11, the condensation heat exchanger 14, the dryer filter 13, the throttling element 12, and the heat absorption path of the heat exchanger 6 are sequentially connected to the inlet of the compressor 11.

[0040] An exhaust gas temperature sensor 18 and an exhaust gas pressure sensor 19 are further provided at the outlet of the compressor 11, and a suction temperature sensor 20 and a suction pressure sensor 21 are further provided at the inlet of the compressor 11.

[0041] The dry cooler 7 is arranged below the condensation heat exchanger 14, and the dry cooler 7 and the condensation heat exchanger 14 share the cooling fan 15, and the cooling fan 15 is arranged below the dry cooler 7.

[0042] In this embodiment, the water pump 4 is a variable frequency water pump, the heater 5 is a pipe-type heating tube, the heat exchanger 6 is a plate heat exchanger, the compressor 11 is a variable frequency compressor, and the throttling element 12 is an electronic expansion valve.

[0043] In this embodiment, an ambient temperature sensor is also conventionally provided at the air return opening of the unit.

[0044] The basic working principle of the unit in this embodiment is as follows:

[0045] For the refrigeration system, when the compressor 11 is turned on, the refrigerant flows from the outlet of the compressor 11 through the condensation heat exchanger 14, the dryer filter 13, the electronic expansion valve 12, and the plate heat exchanger 6 in sequence, and returns to the inlet of the compressor 11, completing the refrigeration cycle through the phase change from gas to liquid and then to gas.

[0046] For the water system, when the water pump 4 is turned on and the three-way valve 8 is adjusted to open both the first branch 16 and the second branch 17, the coolant return water from the end battery pack PACK side is pressurized by the water pump 4 and flows to the first branch 16 and the second branch 17. The coolant in the first branch 16 exchanges heat with the outdoor air through the dry cooler 7, and then converges with the coolant in the second branch 17 at the three-way valve 8 and supplies water to the end battery pack PACK; the coolant in the second branch 17 passes through the heater 5 and the plate heat exchanger 6. When the refrigerant in the refrigeration system compressor 11 circulates, the coolant exchanges heat with the refrigerant in the plate heat exchanger 6, and then converges with the coolant in the first branch 16 at the three-way valve 8 and supplies water to the end battery pack PACK.

[0047] Embodiment 2

[0048] A specific implementation of the energy-saving temperature control method for the natural cold energy storage chiller of the present invention is applied to the natural cold energy storage chiller described in Embodiment 1. The method includes:

[0049] Preset temperature thresholds T1, T2, and T3, and T3 < T2 < T1;

[0050] Judge the ambient temperature t, where the ambient temperature t is the value from the ambient temperature sensor;

[0051] If t ≥ T1, the unit operates in the extreme high temperature condition. When the unit has a refrigeration demand, the compressor 11 of the refrigeration system is turned on for refrigeration cycle, and at the same time, the opening degree of the three-way valve 8 is adjusted to open both the first branch 16 and the second branch 17 of the water system; the coolant passes through the dry cooler 7 in the first branch 16, and the cooler coolant exchanges heat with the outdoor high-temperature air. The outdoor high-temperature air is cooled after passing through the dry cooler 7 and exchanges heat with the high-temperature and high-pressure refrigerant through the condensation heat exchanger 14 under the forced convection of the cooling fan 15. The coolant passes through the heater 5 and the plate heat exchanger 6 in the second branch 17, and exchanges heat with the low-temperature and low-pressure refrigerant in the plate heat exchanger 6. The temperature of the coolant decreases to achieve the refrigeration purpose, and the low-temperature coolant is supplied to the terminal battery pack PACK to provide a reasonable temperature environment for its charging and discharging. The application scenario of the energy storage air conditioner is harsh and the outdoor conditions are complex. The stability and reliability of the chiller operation in the high-temperature scenario are particularly important. By adjusting the three-way valve 8, part of the coolant passes through the dry cooler 7 of the first branch 16, which can reduce the temperature of the outdoor high-temperature air, increase the heat exchange temperature difference between the high-temperature and high-pressure refrigerant in the condensation heat exchanger 14 and the air outside the pipe, effectively reduce the condensation temperature, improve the refrigeration efficiency and operation reliability of the unit, and avoid losses caused by the unit shutting down due to failures in the high-temperature environment.

[0052] If T2 < t ≤ T1, the unit operates in the normal temperature condition. When the unit has a refrigeration demand, the compressor 11 of the refrigeration system is turned on for refrigeration cycle, and at the same time, the three-way valve 8 is adjusted to turn off the first branch 16 and open the second branch 17. At this time, all the coolant passes through the second branch 17 and exchanges heat with the low-temperature and low-pressure refrigerant in the plate heat exchanger 6, and the temperature decreases to achieve the refrigeration purpose.

[0053] When the unit has a heating demand, the compressor 11 of the refrigeration system is turned off. At the same time, the opening degree of the three-way valve 8 is adjusted to open both the first branch 16 and the second branch 17. The coolant temperature rises after passing through the dry cooler 7 in the first branch 16, achieving the heating purpose. At the initial stage of heating, the heater 5 in the second branch 17 is in the off state; when the heating demand continues to increase, the opening degree of the three-way valve 8 is adjusted according to the supply water temperature measured by the supply water temperature sensor 10 to increase the coolant flow rate through the first branch 16, improving the heating capacity of the unit; when the heating capacity of the unit still cannot meet the demand of the terminal battery pack after the coolant flow rate in the first branch 16 increases to the limit, the heater 5 on the second branch 17 is turned on to further increase the heating capacity of the unit. From the above working process, it can be seen that during heating, by adjusting the opening degree of the three-way valve 8, part of the coolant exchanges heat with the outdoor air through the dry cooler 7, using the heat of the outdoor air for heating. This control mode can achieve not turning on the heater 5 or reducing the opening time and frequency of the heater 5, effectively reducing the operating power consumption of the unit and achieving the purpose of energy saving. At the same time, most of the current energy storage chillers with heating functions are equipped with heaters with non-adjustable output, which can only be turned on or off. In actual application scenarios, the opening and closing of the heater will cause fluctuations in the supply water temperature. The method of adjusting the coolant flow rate in the first branch 16 by adjusting the opening degree of the three-way valve 8 in this embodiment can adjust the heating capacity of the chiller and make the temperature control more accurate.

[0054] If T3 < t ≤ T2, the unit operates in a low-temperature condition. When the unit has a refrigeration demand, the natural cold source is preferentially utilized. The refrigeration system is first turned off, and the opening degree of the three-way valve 8 is adjusted to open the first branch 16 of the water system and close the second branch 17. The coolant exchanges heat with the outside air through the dry cooler 7 on the first branch 16 to achieve refrigeration. During this period, the compressor 11 remains off, that is, the natural cold source is preferentially utilized to achieve refrigeration; when the refrigeration demand decreases, the opening degree of the three-way valve 8 is adjusted according to the supply water temperature measured by the supply water temperature sensor 10 to reduce the coolant flow rate through the first branch 16, reducing the refrigeration capacity of the unit; when the refrigeration demand increases again, the opening degree of the three-way valve 8 is adjusted according to the supply water temperature measured by the supply water temperature sensor 10 to increase the coolant flow rate through the first branch 16, increasing the refrigeration capacity of the unit; when the refrigeration demand of the terminal battery pack still cannot be met after the coolant flow rate in the first branch 16 increases to the limit, the opening degree of the three-way valve 8 is adjusted to open the second branch 17, and at the same time, the compressor 11 of the refrigeration system is turned on for refrigeration cycle to further increase the refrigeration capacity of the unit.

[0055] When the unit has a heating demand, the compressor 11 of the refrigeration system is turned off, the opening degree of the three-way valve 8 is adjusted to open both the first branch 16 and the second branch 17, and at the same time, the heater 5 is turned on. As mentioned before, the heater 5 can only be turned on and off, and the heater 5 and the compressor 11 cannot be turned on at the same time. The opening degree of the three-way valve 8 is adjusted so that the cooling capacity provided by the dry cooler 7 passing through the first branch 16 is less than the heating capacity provided by the heater 5 passing through the second branch 17, ensuring that the net heating capacity of the unit is positive. When the heating demand increases, the opening degree of the three-way valve 8 is adjusted to reduce the flow rate of the secondary refrigerant in the first branch 16 and the cooling capacity provided by the dry cooler 7 in the first branch 16, thereby increasing the net heating capacity of the unit. The control mode in this embodiment can achieve adjustable heating capacity of the water chiller and precise temperature control.

Claims

1. A natural cooling energy storage chiller, characterized in that: Including water system and refrigeration system, including: The water system comprises an expansion tank (3), a water pump (4), a heater (5), a heat exchanger (6), a dry cooler (7), and a three-way valve (8); The return water on the terminal battery pack side is connected to the inlet of the water pump (4); the outlet of the water pump (4), the dry cooler (7), and the first inlet of the three-way valve (8) are connected in sequence to form a first branch path (16); the outlet of the water pump (4) is also connected in sequence to the heater (5), the heat release path of the heat exchanger (6), and the second inlet of the three-way valve (8) to form a second branch path (17); the outlet of the three-way valve (8) serves as a water supply port on the terminal battery pack side; the three-way valve (8) is equipped with a water valve actuator, and the water valve actuator is used to control the opening of the three-way valve (8) through an analog electrical signal; the expansion tank (3) is arranged at the inlet of the water pump (4); The water pump (4) inlet is also provided with a return water temperature sensor (1) and a return water pressure sensor (2), and the water pump (4) outlet is also provided with a water supply pressure sensor (9) and a water supply temperature sensor (10); The refrigeration system is connected to the heat absorption path of the heat exchanger (6).

2. A natural cooling energy storage chiller according to claim 1, characterized in that: The water pump (4) is a variable frequency water pump.

3. A natural cooling energy storage chiller according to claim 1, characterized in that: The heater (5) is a pipeline heating tube type.

4. A natural cooling energy storage chiller according to claim 1, characterized in that: The heat exchanger (6) is a plate heat exchanger.

5. The natural cooling energy storage chiller according to claim 1, characterized in that: The refrigeration system comprises a compressor (11), a throttling element (12), a drying filter (13), a condensing heat exchanger (14), and a heat dissipation fan (15); The compressor (11) outlet, the condensing heat exchanger (14), the drying filter (13), the throttling element (12), the heat absorption passage of the heat exchanger (6) and the compressor (11) in sequence are connected.

6. A natural cooling energy storage chiller according to claim 5, characterized in that: The compressor (11) is a variable frequency compressor, and the throttling element (12) is an electronic expansion valve.

7. A natural cooling energy storage chiller according to claim 5, characterized in that: The dry cooler (7) is arranged below the condensing heat exchanger (14), and the dry cooler (7) and the condensing heat exchanger (14) share the heat dissipation fan (15).

8. An energy-saving temperature control method for a natural cooling energy storage chiller, applied to the natural cooling energy storage chiller as claimed in any one of claims 1 to 7, characterized in that: include: Preset temperature thresholds T1, T2, T3, and T3<T2<T1; Determine the ambient temperature t; If t≥T1, the unit is operating at an extreme high temperature condition, during cooling, the refrigeration system is started, and the opening of the three-way valve (8) is adjusted so that both the first branch line (16) and the second branch line (17) of the water system are opened; If T2<t≤T1, the unit operates at normal temperature. When cooling, the refrigeration system is started, and the three-way valve (8) is adjusted to close the first branch (16) and open the second branch (17); when heating, the refrigeration system is closed, and the opening of the three-way valve (8) is adjusted to open both the first branch (16) and the second branch (17), and the opening of the three-way valve (8) is adjusted according to the water supply temperature measured by the water supply temperature sensor (10) or the return water temperature measured by the return water temperature sensor (1) to adjust the flow rate of the refrigerant in the first branch (16); If T3<t≤T2, the unit operates in a low temperature condition. When cooling, the refrigeration system is first closed, and the opening of the three-way valve (8) is adjusted to open the first branch (16) of the water system. The opening of the three-way valve (8) is adjusted according to the water supply temperature measured by the water supply temperature sensor (10) or the return water temperature measured by the return water temperature sensor (1) to adjust the flow rate of the refrigerant in the first branch (16). When heating, the refrigeration system is closed, and the opening of the three-way valve (8) is adjusted to open both the first branch (16) and the second branch (17). At the same time, the heater (5) is turned on, and the opening of the three-way valve (8) is adjusted so that the cooling capacity provided by the dry cooler (7) through the first branch (16) is less than the heating capacity provided by the heater (5) through the second branch (17).

9. The energy-saving temperature control method of a natural cooling energy storage chiller according to claim 8, characterized in that: If T2<t≤T1, during heating, when the flow rate of the coolant in the first branch (16) increases to a limit and the heating amount of the unit still does not meet the demand of the terminal battery pack, the heater (5) on the second branch (17) is turned on.

10. The energy-saving temperature control method of a natural cooling energy storage chiller according to claim 8, characterized in that: If T3<t≤T2, during refrigeration, when the coolant flow rate of the first branch (16) increases to the limit but still cannot meet the refrigeration demand of the terminal battery pack, the opening of the three-way valve (8) is adjusted to open the second branch (17), and the refrigeration system is started at the same time.

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