A cold accumulation tank based district cooling system

Abstract

The application relates to a cold storage tank-based regional cooling supply system, which comprises a three-stage cold storage tank group, an intelligent prediction module, an optimization control module and a cold storage execution unit; wherein the three-stage cold storage tank group comprises physically isolated deep cold tanks, medium cold tanks and shallow cold tanks, the medium cold tanks wrap the deep cold tanks to form a concentric structure, and a heat transfer integrated interface is arranged between the deep cold tanks and the medium cold tanks to transfer residual cold; the intelligent prediction module is used for outputting a park future 72-hour load curve and a load change rate through a preset load prediction model; the optimization control module is used for calculating a global priority index P through a preset index calculation formula according to a park real-time electricity price, a real-time cold storage rate of the three-stage cold storage tank group and the load change rate; and the cold storage execution unit is used for executing cold storage and cold release operations according to the global priority index P. The application has the effect of improving the cold storage efficiency and realizing dynamic supply-demand balance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of cold storage tank area cooling, and in particular to a cold storage tank based area cooling system. BACKGROUND

[0002] Area cooling is a systematic technology that prepares air conditioning chilled water through a centralized cooling station set in a building group, and supplies cooling to multiple buildings through circulating pipelines. This technology can reduce repeated investment in refrigeration equipment, reduce urban peak power load, and achieve intensive energy management. In existing area cooling systems, there is a lack of effective cold storage devices. To meet the cooling load demand of users, area cooling systems are usually configured according to the maximum cooling load demand.

[0003] Chinese patent application CN110595102A discloses a multi-purpose area cooling system and control method. The system includes a lithium bromide chiller unit, an electric chiller unit, a heat exchange mechanism, a cooling tower, a heat storage water tank, a cold storage water tank, and a gas turbine inlet air cooler. The lithium bromide chiller unit is connected to the gas turbine inlet air cooler and the cold storage water tank and provides a cold source. The cold storage water tank is connected to the gas turbine inlet air cooler. The heat exchange mechanism is connected to the lithium bromide chiller unit and the heat storage water tank. The cooling tower is connected to the lithium bromide chiller unit and the electric chiller unit. The area cooling system of the application sets a cold storage water tank to achieve the cold storage function. The area cooling system sets a gas turbine inlet air cooler to achieve the gas turbine inlet air cooling function. The area cooling system sets a heat exchange mechanism and a heat storage water tank to achieve the hot water supply function. However, only a single cold storage tank is used for cold storage, which not only has low cold storage efficiency and slow fault recovery, but also cannot respond to complex load changes, resulting in low cold storage utilization rate, and often insufficient cooling or waste of cooling capacity.

[0004] In view of the above related technologies, the existing area cooling system has low cold storage efficiency and cannot respond to complex cooling load changes in industrial parks. SUMMARY

[0005] To solve the above problems, the present application provides a cold storage tank based area cooling system.

[0006] In a first aspect, the present application provides a cold storage tank based area cooling system, which adopts the following technical solution:

[0007] A cold storage tank based area cooling system, comprising:

[0008] The three-stage cold storage tank group comprises a physically isolated deep cold tank, a middle cold tank and a shallow cold tank, the middle cold tank wraps the deep cold tank to form a concentric structure, a heat transfer integrated interface is arranged between the deep cold tank and the middle cold tank for transferring residual cold, and the middle cold tank and the shallow cold tank are jointly connected with a cold supplement heat exchanger; the middle cold tank and the shallow cold tank are both wrapped with aerogel thermal insulation layers outside; the deep cold tank has a cold storage temperature of -10 to -5 DEG C and is used for storing basic cold quantity; the middle cold tank has a cold storage temperature of 0 to 4 DEG C and is used for storing conventional operation cold quantity; and the shallow cold tank has a cold storage temperature of 4 to 8 DEG C and is used for storing terminal adjustment cold quantity.

[0009] The intelligent prediction module is used for acquiring park meteorological data, building data and historical load data, and outputting a park future 72-hour load curve and a load change rate through a preset load prediction model; the load prediction model is an LSTM neural network model obtained through historical data iterative training;

[0010] The optimization control module is used for acquiring a park electricity price policy to determine a park real-time electricity price, and collecting a real-time cold storage rate of the three-stage cold storage tank group, and calculating a global priority index P through a preset index calculation formula according to the park real-time electricity price, the real-time cold storage rate of the three-stage cold storage tank group and the load change rate.

[0011] The cold storage execution unit is used for performing the following operations according to the global priority index P:

[0012] When P < 0.4, the deep cold tank is started to store cold, and the middle cold tank synchronously absorbs residual cold of the deep cold tank interface;

[0013] When 0.4 ≤ P < 0.7, the middle cold tank is started to store cold;

[0014] When P ≥ 0.7, the shallow cold tank cold quantity is released, and the middle cold tank is started to supplement cold when the shallow cold tank cold quantity is insufficient.

[0015] Preferably, the index calculation formula is specifically:

[0016] ;

[0017] ;

[0018] ;

[0019] wherein, is a normalized electricity price, is a park real-time electricity price, and are maximum and minimum values of a current electricity price interval of the park, respectively; is a real-time cold storage rate of the three-stage cold storage tank group, is a real-time cold storage quantity of the three-stage cold storage tank group, The maximum cold storage capacity of the three-stage cold storage tank group is: The load change rate represents the fluctuation speed of the user's cold load, and a positive value indicates a load increase, and a negative value indicates a load decrease.

[0020] Preferably, when the P value is greater than 0.65, the automatic adjustment of the P value weight is: % / h, the automatic adjustment of the P value weight is:

[0021] ;

[0022] and when P≥0.65, the shallow cold tank is started 2 hours in advance.

[0023] Preferably, the outer wall of the deep cold tank is made of a stainless steel base layer, the stainless steel base layer is S30408 austenitic stainless steel, and the thickness is 8-12mm; the inner wall of the medium cold tank is made of a low-alloy high-strength steel base layer, the outer walls of the medium cold tank and the shallow cold tank are both made of a composite structure of a carbon steel base layer and a polyurethane foam insulation layer, the density of the polyurethane foam insulation layer is 30-50kg / m³, and the closed cell rate is ≥95%.

[0024] Preferably, the deep cold tank contains ice slurry cold storage medium, the ice slurry has an ice crystal volume fraction of 20%-40% and an average ice crystal particle size of ≤500μm; the medium cold tank contains an ethylene glycol aqueous solution, the ethylene glycol aqueous solution has a mass concentration of 20%-30% and a freezing point of ≤-10℃; and the shallow cold tank contains a paraffin-based phase change material, which has a phase change temperature of 5 degrees Celsius.

[0025] Preferably, the heat transfer integrated interface specifically includes a titanium alloy grid structure arranged on the outer wall of the deep cold tank and an aluminum-magnesium alloy layer arranged on the inner wall of the medium cold tank, and a heat-conducting silicone grease is filled between the titanium alloy grid structure and the aluminum-magnesium alloy layer for coupling.

[0026] Preferably, a semiconductor power generation module is further arranged between the titanium alloy grid structure and the aluminum-magnesium alloy layer, the power generation sheet of the semiconductor power generation module is embedded in the recessed part of the titanium alloy grid, the cold surface of the power generation sheet directly contacts the base layer of the recessed part of the titanium alloy grid structure, and the hot surface is coupled with the aluminum-magnesium alloy layer through heat-conducting silicone.

[0027] Preferably, micro-grooves are arranged on the surface of the titanium alloy grid structure, the depth of the micro-grooves is 0.2-0.5mm, the width is 0.3-0.8mm, and the interval is 1-3mm; micro-channels are arranged on the inner surface of the aluminum-magnesium alloy layer, the depth of the micro-channels is 0.3-0.6mm, the width is 0.5-1.0mm, and the interval is 2-4mm; and the micro-grooves and the micro-channels are staggered.

[0028] Preferably, the aerogel thermal insulation layer comprises a first SiO2 aerogel layer, a carbon fiber grid reinforcing layer and a second SiO2 aerogel layer arranged in sequence, the density of the first SiO2 aerogel layer and the second SiO2 aerogel layer is 150-200 kg / m³, the thermal conductivity is ≤0.018 W / (m·K), and the areal density of the carbon fiber grid reinforcing layer is 200-300 g / m².

[0029] Preferably, the step of starting the intermediate cold tank to supplement cooling when the cold energy of the shallow cold tank is insufficient comprises the following steps:

[0030] The optimization control module collects the cold storage rate N of the shallow cold tank and the global priority index P in real time q , and starts the cooling supplement program when P≥0.7 and N q is less than the pre-set cooling supplement threshold value;

[0031] The pre-set glycol aqueous solution circulating pump is controlled to send the glycol aqueous solution in the intermediate cold tank into the cooling supplement heat exchanger to circulate and preheat for 10 minutes, so as to reduce the pipe temperature in the cooling supplement heat exchanger;

[0032] The glycol aqueous solution in the intermediate cold tank is sent into the cooling supplement heat exchanger to exchange heat with the terminal loop of the shallow cold tank;

[0033] The cooling supplement program is normally terminated when P<0.6 and N q is greater than the pre-set cold storage threshold value;

[0034] When the cooling supplement lasts for more than 2 hours and the cold storage rate of the shallow cold tank is still less than the pre-set cooling supplement threshold value, the deep cold tank is started to store cold and supplement the intermediate cold tank through the heat transfer integrated interface, and a fault alarm is issued.

[0035] In summary, the present application has at least one of the following beneficial technical effects:

[0036] 1. The present application divides the regional cooling demand, and through the setting of the three-level cold storage tank group, the deep cold tank, the intermediate cold tank and the shallow cold tank form a gradient cold storage temperature zone, realize layered cold storage, respectively adapt to long-term stable cold demand, daytime main cold demand and short-term fluctuating cold demand, the cold storage efficiency is significantly improved, and the waste of cold quality caused by single temperature zone cold storage is avoided; the heat transfer integrated interface of the deep cold tank and the intermediate cold tank realizes directional transfer of excess cold, and the intermediate cold tank and the shallow cold tank form an emergency cooling supplement channel through the cooling supplement heat exchanger, further improving the cold storage efficiency on the basis of improving the cold storage efficiency, effectively improving the stability of the cooling supply; at the same time, the intelligent prediction module outputs a 72-hour load curve based on the LSTM model, so that the system can store cold in advance before the load peak, avoiding temporary insufficient cooling supply; the optimization control module fuses the electricity price, the cold storage rate and the load change rate to calculate the global priority index P, which drives the cold storage execution unit to automatically switch modes, greatly improves the response efficiency of the cooling system to load mutation, and ensures the dynamic balance between supply and demand;

[0037] 2. The heat transfer integrated interface is coupled by titanium alloy grid, aluminum magnesium alloy layer and heat-conducting silicone grease, utilizes the high thermal conductivity of titanium alloy and aluminum magnesium alloy, fills the gap by combining heat-conducting silicone grease, eliminates the air insulation layer, makes the high thermal conductivity characteristics of titanium alloy and aluminum magnesium alloy fully play, enhances the heat transfer efficiency between the deep cooling tank and the medium cooling tank, makes the medium cooling tank more fully absorb the waste heat of the deep cooling tank, and improves the energy gradient utilization efficiency.

[0038] 3. The index calculation formula realizes adaptive regulation and control of economy in a conventional scene and response in a fluctuation scene by presetting a weight and weight correction in a load mutation, and further improves the response efficiency of the cooling supply system to the load mutation. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 is a system block diagram of a regional cooling supply system based on a cold storage tank in the embodiment of the present application;

[0040] Figure 2 is a transverse cross-sectional schematic view of a medium cooling tank and a deep cooling tank in the embodiment of the present application;

[0041] Figure 3 is a method flowchart for starting the medium cooling tank to supplement cooling when the cold capacity of the shallow cooling tank is insufficient in the embodiment of the present application;

[0042] Figure 4 is a layer structure schematic view of an outer wall of a shallow cooling tank in the embodiment of the present application;

[0043] Figure 5 is a cross-sectional schematic view of a heat transfer integrated interface in the embodiment of the present application.

[0044] BRIEF DESCRIPTION OF DRAWINGS 1. Three-stage cold storage tank group; 11. Deep cooling tank; 111. Stainless steel base layer; 112. Titanium alloy grid structure; 113. Micro groove; 12. Medium cooling tank; 121. Low-alloy high-strength steel base layer; 122. Aluminum magnesium alloy layer; 123. Microchannel; 13. Shallow cooling tank; 131. Carbon steel base layer; 132. Polyurethane foam insulation layer; 2. Intelligent prediction module; 3. Optimization control module; 4. Cold storage execution unit; 5. Heat transfer integrated interface; 51. Heat-conducting silicone grease; 52. Semiconductor power generation module; 6. Cooling supplement heat exchanger; 7. Aerogel insulation layer; 71. First SiO2 aerogel layer; 72. Carbon fiber grid reinforcement layer; 73. Second SiO2 aerogel layer. DETAILED DESCRIPTION

[0045] The following will be described in detail in combination with the accompanying Figures 1-5 The present application is further described in detail.

[0046] The base cooling capacity is the basic cooling capacity for ensuring the continuous operation of the core function in the regional cooling supply system, and the cooling demand thereof has long-term stability (the time scale is days or weeks), and is not affected by short-term load fluctuations (such as personnel flow and temporary start and stop of equipment) in hours. Application scenarios: focus on the core area of the park that runs continuously for 24 hours, such as data center rooms (server cooling demand is constant), medical refrigerators (low-temperature environment maintenance), emergency command centers (equipment continuous operation), and the like, and the cooling capacity release rate fluctuation is ≤5% / h, to ensure uninterrupted core functions.

[0047] The conventional operation cooling capacity is the main cooling capacity for supporting the daily main activities of the region, covering the non-extreme fluctuation of the cooling load during the day (such as 8:00-22:00), and is the “intermediate level cooling capacity” connecting the base cooling capacity and the terminal regulation cooling capacity. Application scenarios: suitable for office areas, commercial areas, cultural and sports venues, and the like, to meet the conventional environmental cooling demand and production cooling demand.

[0048] The terminal regulation cooling capacity is the fine-tuning cooling capacity for compensating short-term and small-amplitude load fluctuations (time scale is 15 minutes to 2 hours), and the core function thereof is to accurately correct the deviation between the conventional operation cooling capacity and the actual terminal demand, to ensure the cooling temperature precision. The fluctuation sources: mainly caused by temporarily activated equipment or environmental mutations, such as short-time gathering of personnel in the conference room (cooling demand increases by 10%-20%), sudden increase of the intensity of solar radiation in the afternoon (increased heat transfer of the peripheral structure), temporary start of process equipment (such as small cooling devices in the laboratory), and the like, and the terminal regulation cooling capacity can quickly offset such fluctuations, to avoid frequent start and stop of the conventional operation cooling capacity.

[0049] It can be seen that the cooling supply demand environment of the regional cooling supply system is complex. It is difficult to effectively supply cooling.

[0050] Embodiments of the present application disclose a regional cooling supply system based on a cold storage tank. Referring to Figure 1 and Figure 2The application discloses a cold storage tank-based regional cooling supply system, which comprises a three-stage cold storage tank group 1, an intelligent prediction module 2, an optimization control module 3 and a cold storage execution unit 4. The three-stage cold storage tank group 1, the intelligent prediction module 2, the optimization control module 3 and the cold storage execution unit 4 are connected in communication with each other. The three-stage cold storage tank group 1 comprises a physically isolated deep cold tank 11, a medium cold tank 12 and a shallow cold tank 13. The medium cold tank 12 wraps the deep cold tank 11 to form a concentric structure, and a heat transfer integrated interface 5 is arranged between the deep cold tank 11 and the medium cold tank 12 to transfer residual cold. The medium cold tank 12 and the shallow cold tank 13 are jointly connected with a cold supplementing heat exchanger 6. The medium cold tank 12 and the shallow cold tank 13 are both wrapped with aerogel thermal insulation layers 7. The deep cold tank 11 has a cold storage temperature of -10 to -5 DEG C and is used for storing basic cold capacity. The medium cold tank 12 has a cold storage temperature of 0 to 4 DEG C and is used for storing regular operation cold capacity. The shallow cold tank 13 has a cold storage temperature of 4 to 8 DEG C and is used for storing terminal adjustment cold capacity. The intelligent prediction module 2 is used for acquiring park meteorological data, building data and historical load data, and outputting a park future 72-hour load curve and a load change rate through a preset load prediction model. The load prediction model is an LSTM neural network model obtained through historical data iterative training, and specific training steps are not described herein again. The optimization control module 3 is used for acquiring an electricity price policy of the park to determine a real-time electricity price of the park, collecting a real-time cold storage rate of the three-stage cold storage tank group 1, and calculating a global priority index P through a preset index calculation formula according to the real-time electricity price of the park, the real-time cold storage rate of the three-stage cold storage tank group 1 and the load change rate. The cold storage execution unit 4 is used for performing the following operations according to the global priority index P:

[0051] When P<0.4, the deep cold tank 11 is started to store cold, and the medium cold tank 12 synchronously absorbs residual cold of the interface of the deep cold tank 11;

[0052] When 0.4<=P<0.7, the medium cold tank 12 is started to store cold;

[0053] When P is greater than or equal to 0.7, the cold energy of the shallow cooling tank 13 is released, and when the cold energy of the shallow cooling tank 13 is insufficient, the medium cooling tank 12 is started to supplement cooling. The present application divides the regional cooling demand, and through the setting of the three-level cold storage tank group 1, the deep cooling tank 11, the medium cooling tank 12 and the shallow cooling tank 13 form a gradient cold storage temperature zone, realize layered cold storage, respectively adapt to long-term stable cold demand, daytime main cold demand, short-term fluctuation cold demand, the cold storage efficiency is improved significantly, avoid the waste of cold quality caused by single temperature zone cold storage (such as the irreversible loss caused by using-10℃ cold to supply 8℃ demand); and the heat transfer integrated interface 5 of the deep cooling tank 11 and the medium cooling tank 12 realizes directional transfer of excess cold, and the medium cooling tank 12 and the shallow cooling tank 13 form an emergency cold supplement channel through the cold supplement heat exchanger 6, further improve the cold storage efficiency on the basis of improving the cold storage efficiency, effectively improve the stability of the cold supply; at the same time, the intelligent prediction module 2 outputs the 72-hour load curve based on the LSTM model, so that the system can store cold in advance before the load peak, and avoid temporary insufficient cold supply; the optimization control module 3 calculates the global priority index P by combining the electricity price, the cold storage rate and the load change rate, drives the cold storage execution unit 4 to automatically switch modes, greatly improves the response efficiency of the cold supply system to load mutation, and ensures the dynamic balance of supply and demand.

[0054] The specific index calculation formula is:

[0055] ;

[0056] ;

[0057] ;

[0058] wherein, is the normalized electricity price, is the real-time electricity price of the park, and are the maximum value and the minimum value of the current electricity price interval of the park, respectively; is the real-time cold storage rate of the three-level cold storage tank group 1, is the real-time cold storage amount of the three-level cold storage tank group 1, is the maximum cold storage amount of the three-level cold storage tank group 1; is the load change rate, representing the fluctuation speed of user cooling load, positive value indicating load rise, negative value indicating load drop. Through the setting of the index calculation formula, the current electricity price of the park is mainly weighted, the electricity price is normalized, the coupling of electricity price, cold storage state and load fluctuation is realized, the economy, system state and demand urgency are quantified as a unified index P, the balance between cost minimization and cooling reliability is realized, and the cooling system forms a closed loop optimization in economy, response speed and reliability. It should be noted that the electricity price policy is different in different regions. For example, in the region with large peak-valley electricity price difference, such as industrial and commercial park, the peak electricity price is more than 3 times the valley electricity price, and the electricity cost difference is large. If fixed period cold storage is adopted, it is difficult to respond to the adjustment of regional electricity price policy, which may lead to insufficient cold storage. By normalizing the electricity price, the maximum utilization of valley electricity is ensured by responding to the change of electricity price in real time. There is also a region with short peak electricity price period and high price (such as the core area of first-tier city, 1-2 hours / day, 2 times the peak electricity price), and the electricity cost difference is larger. Due to the lack of prediction of short peak period, the existing technology is forced to start the unit during the peak period due to the lag of response, and the closed loop of pre-storage before peak, release and storage during peak, and energy supplement after peak is realized by normalizing the electricity price and linking with load prediction, which perfectly adapts to the short peak policy.

[0059] There are also some step electricity price regions with step electricity price (limiting total electricity consumption). The price of different electricity consumption is different in this region. When the monthly electricity consumption is close to the step threshold, the load prediction is higher than the current stage margin, and it will be dynamically corrected due to the risk of potential high electricity price (high price of the second step), even if the current electricity price is still low, it will be increased, which may cause the unified index P to increase by 0.4-0.7. At this time, the current step margin will be used to preferentially store cold in the cold tank 12 to reduce immediate electricity purchase. The main reason is that the deep cold tank 11 stores the base cold of-10 to-5℃, which requires the refrigeration unit to provide a lower evaporation temperature (usually ≤-12℃), and the coefficient of performance (COP) of the refrigeration unit decreases significantly with the decrease of evaporation temperature (such as-12℃, COP is about 3.0, which is much lower than 4.5 at 0℃). That is, when storing the same amount of cold, the power consumption of the deep cold tank 11 is about 30%-40% higher than that of the medium cold tank 12. At this time, the cost is balanced by sacrificing the cooling quality, which further highlights the superiority of the index calculation formula and the dynamic balance control ability.

[0060] In addition, in order to further improve the response speed of load mutation, when the load change rate is greater than 0.5% / h, the P value weight is automatically adjusted as follows:

[0061] ;

[0062] ​and when P≥0.65, the shallow cold tank 13 is started to store cold 2 hours in advance. The exponential calculation formula realizes adaptive regulation and control of the economy in the conventional scene and the response in the fluctuation scene by presetting the weight and correcting the weight when the load suddenly changes, and further improves the response efficiency of the cooling system to the load mutation. In addition, under the condition of large fluctuation, although the phase change material (PCM) of the shallow cold tank 13 has the characteristics of rapid cold storage and release, the cold storage process needs a certain time. When P≥0.65, it often corresponds to the period when the power consumption peak is about to enter, at this time, starting the shallow cold tank 13 to store cold in advance can concentrate the cold storage power consumption in the relatively low electricity price preparation period, quickly respond to the surge of load, avoid the lag of cooling, and at the same time avoid the cold storage operation in the load peak period, and improve the stability of the system.

[0063] It should be emphasized that the functional positioning of the shallow cold tank 13 determines the cold storage mode. The core function of the shallow cold tank 13 is to store end regulation cold, which is used to compensate for short-term and small-amplitude load fluctuations. Its design capacity is usually small, which is 30%-50% of the intermediate cold tank 12 in this embodiment, and the cold demand has instantaneity. Therefore, the cold storage of the shallow cold tank 13 is a see-saw type supplement in the system operation, avoiding occupying the core cold storage resources (such as preferentially guaranteeing the deep cold tank 11 in the valley electricity period). When P<0.4, the deep cold tank 11 stores the base cold through ice slurry, and the intermediate cold tank 12 absorbs the excess cold of the deep cold tank 11 through the heat transfer integrated interface 5. When the intermediate cold tank 12 is full of cold through the excess cold, the excess cold will be further transferred to the shallow cold tank 13 through the cold supplement heat exchanger 6, so that it is passively stored. When the intermediate cold tank is directly stored and full, the excess cold will be further transferred to the shallow cold tank 13 through the cold supplement heat exchanger 6, so that it is passively stored. When the cold storage rate N q of the shallow cold tank 13 is less than the preset cold supplement threshold, and is in the valley electricity idle period, the small-power refrigeration equipment in the cooling system can also be started to actively store cold.

[0064] Referring to Figure 3 , the above-mentioned starting of the intermediate cold tank 12 to supplement cold when the cold of the shallow cold tank 13 is insufficient specifically includes the following steps:

[0065] A1, the optimization control module 3 collects the cold storage rate N q of the shallow cold tank 13 and the global priority index P in real time, and when P≥0.7 and N q is less than the preset cold supplement threshold, the cold supplement program is started; the cold supplement threshold is set by the management personnel, which is 30% in this embodiment;

[0066] A2, control the pre-set glycol water solution circulating pump to send the glycol water solution in the intermediate cold tank 12 into the cold supplement heat exchanger 6 to circulate and preheat for 10 minutes, so as to reduce the pipe temperature in the cold supplement heat exchanger 6;

[0067] A3, the glycol water solution of the intermediate cold tank 12 is sent into the cold supplement heat exchanger 6 to exchange heat with the end loop of the shallow cold tank 13.

[0068] A4、When P < 0.6 and N q Normal termination of the cold supplement program when the cold storage threshold is greater than the preset cold storage threshold;

[0069] A5, when the cold supplement lasts more than 2 hours and the cold storage rate of the shallow cold tank 13 is still less than the preset cold supplement threshold, start the cold storage of the deep cold tank 11 and supplement the cold of the medium cold tank 12 through the heat transfer integrated interface 5, and issue a fault alarm. Through the above steps, when the cold storage rate of the shallow cold tank 13 is insufficient during the cold release process using the shallow cold tank 13, the medium cold tank 12 is supplemented to ensure stable cold supply. At the same time, the ethylene glycol solution in the medium cold tank 12 is circulated and preheated for 10 minutes during the cold supplement, reducing the temperature difference impact of the cold supplement heat exchanger 6 pipeline, protecting the equipment while improving the heat exchange efficiency. And when the cold supplement lasts more than 2 hours and the cold storage rate of the shallow cold tank 13 is still less than the preset cold supplement threshold, start the cold storage of the deep cold tank 11 and supplement the cold of the medium cold tank 12 through the heat transfer interface, forming a three-level guarantee of medium cold tank 12 main supplement, deep cold tank 11 emergency supplement and fault warning, avoiding the depletion of cold energy of the medium cold tank 12 due to continuous cold supplement, greatly reducing the risk probability of cold supply interruption.

[0070] Further, with reference to Figure 4 , the outer wall of the deep cold tank 11 adopts a stainless steel base layer 111, the stainless steel base layer 111 is S30408 austenitic stainless steel, the thickness is 8-12mm, and it is resistant to low-temperature corrosion and suitable for deep cold environment. The inner wall of the medium cold tank 12 adopts a low-alloy high-strength steel base layer 121 to improve the structural strength. The outer walls of the medium cold tank 12 and the shallow cold tank 13 both adopt a composite structure of a carbon steel base layer 131 and a polyurethane foam insulation layer 132, the density of the polyurethane foam insulation layer 132 is 30-50kg / m³, and the closed cell rate is ≥95%. Both structural stability and insulation performance are considered, cold loss through the tank wall is reduced, and the temperature in the tank is maintained stable.

[0071] With reference to Figure 4 , the aerogel insulation layer 7 includes a first SiO2 aerogel layer 71, a carbon fiber grid reinforcement layer 72 and a second SiO2 aerogel layer 73 arranged in sequence, the density of the first SiO2 aerogel layer 71 and the second SiO2 aerogel layer 73 is 150-200kg / m³, the thermal conductivity is ≤0.018W / (m·K), and the areal density of the carbon fiber grid reinforcement layer 72 is 200-300g / m². The overall cold loss of the medium cold tank 12 and the shallow cold tank 13 is reduced, the temperature in the tank is maintained stable, and the insulation performance of the medium cold tank 12 and the shallow cold tank 13 is enhanced.

[0072] Further, the deep cooling tank 11 contains ice slurry cold storage medium, the ice crystal volume fraction of the ice slurry is 20%-40%, the average particle size of the ice crystal is ≤500μm; the cold storage density is high, and it is suitable for basic cold storage. The medium temperature tank 12 contains glycol water solution, the mass concentration of the glycol water solution is 20%-30%, and the freezing point is ≤-10℃; low-temperature freezing is avoided, and it is suitable for conventional cold storage. The shallow cooling tank 13 contains paraffin-based phase change material, and the phase change temperature is 5 degrees Celsius. The phase change temperature matches the terminal demand, the cold release is stable, it is suitable for terminal adjustment, the cold storage medium and the function of each tank are accurately matched, and the cold storage and cold release efficiency are improved.

[0073] With reference to Figure 5 The heat transfer integrated interface 5 specifically includes a titanium alloy grid structure 112 arranged on the outer wall of the deep cooling tank 11 and an aluminum-magnesium alloy layer 122 on the inner wall of the medium temperature tank 12, and the titanium alloy grid structure 112 and the aluminum-magnesium alloy layer 122 are coupled by filling a heat-conducting silicone grease 51 therebetween. In the embodiment, the grid spacing of the titanium alloy grid structure 112 is 50mm×50mm, and the rib plate size is 8mm high and 5mm wide, so that the heat exchange area is expanded by the grid structure. The heat transfer integrated interface 5 is coupled by the titanium alloy grid (on the deep cooling tank 11 side), the aluminum-magnesium alloy layer 122 (on the medium temperature tank 12 side) and the heat-conducting silicone grease 51, and the high thermal conductivity of the titanium alloy and the aluminum-magnesium alloy is utilized, and the gap is filled with the heat-conducting silicone grease 51 (to eliminate the air insulation layer), so that the high thermal conductivity of the titanium alloy and the aluminum-magnesium alloy can be fully utilized, the heat transfer efficiency between the deep cooling tank 11 and the medium temperature tank 12 is enhanced, the medium temperature tank 12 can more fully absorb the excess cold of the deep cooling tank 11, and the energy cascade utilization efficiency is improved.

[0074] In addition, the overall material cooperation takes into account the structural stability and low-temperature adaptability. First, the outer wall of the deep cooling tank 11 is made of S30408 austenitic stainless steel, which has excellent low-temperature toughness and good intergranular corrosion resistance. The titanium alloy grid structure 112 includes a TA2 titanium alloy base layer (2-3mm thick) and a titanium alloy grid TA10 material, which not only has excellent heat transfer performance, but also can improve the surface hardness and prevent stress cracking in a deep cooling environment. The inner wall of the medium temperature tank 12 is made of Q345R low-alloy high-strength steel, which has the advantages of high strength and good welding performance, and the aluminum-magnesium alloy plate enhances the heat conductivity, so that the inner wall structure is stable and has good heat conductivity. More importantly, the performance parameters of the interface material are accurately matched with the low-temperature environment, the elastic modulus of the titanium alloy grid is 105GPa at-10℃, and the Poisson's ratio is 0.34, so that the structural integrity in the cold shrink state is ensured; and the thermal conductivity coefficient of the aluminum-magnesium alloy layer 122 at 0℃ is about 5% higher than that at room temperature, and the electronic scattering is further reduced at low temperature to further reduce the thermal resistance, so that the structure is reliable and the heat transfer is efficient.

[0075] With reference to Figure 5The semiconductor power generation module 52 is further arranged between the titanium alloy grid structure 112 and the aluminum-magnesium alloy layer 122, and the power generation sheet of the semiconductor power generation module 52 is embedded in the recess of the titanium alloy grid, the cold surface of the power generation sheet directly contacts the base layer of the recess of the titanium alloy grid structure, and the hot surface is coupled with the aluminum-magnesium alloy layer 122 through the heat-conducting silica gel. The semiconductor power generation module 52 is additionally arranged at the heat transfer interface, power generation is realized by using the temperature difference between the deep cooling tank 11 and the medium cooling tank 12, and energy recovery in the cold quantity transmission process is realized; the power generation sheet is embedded in the titanium alloy grid and coupled through the heat-conducting material, efficient utilization of the temperature difference is ensured, the comprehensive energy utilization rate of the system is improved, and energy saving and efficiency increasing are realized. The DC-DC converter is connected with the semiconductor power generation module 52, 5V direct current is output as power supply for various controllers of the optimization control module 3, and the excess electric quantity is stored in the energy storage battery.

[0076] Referring to Figure 5 The surface of the titanium alloy grid structure 112 is provided with micro grooves 113, the depth of the micro grooves 113 is 0.2-0.5mm, the width is 0.3-0.8mm, and the interval is 1-3mm; the inner surface of the aluminum-magnesium alloy layer 122 is provided with micro channels 123, the depth of the micro channels 123 is 0.3-0.6mm, the width is 0.5-1.0mm, and the interval is 2-4mm; the micro grooves 113 and the micro channels 123 are staggered and distributed, so that the contact area of the heat-conducting silica grease 51 at the interface is increased by 30%-50%. The interface heat transfer efficiency is further strengthened, the residual cold loss is reduced, and the energy transmission effect is improved.

[0077] The above examples are only used to illustrate the technical solutions of the present application, and not to limit the protection scope of the application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application. Although the present application is described in detail with reference to the above examples, those skilled in the art can still combine, add or delete the features in the embodiments of the present application according to the circumstances without creative labor, so as to obtain different other technical solutions which do not deviate from the concept of the present application in essence, and these technical solutions also belong to the scope of the present application.

Claims

1. A district cooling system based on a cold storage tank, characterized in that: include: A three-stage cold storage tank group (1) includes a physically isolated deep cold tank (11), an intermediate cold tank (12) and a shallow cold tank (13), wherein the intermediate cold tank (12) wraps the deep cold tank (11) to form a concentric structure, a heat transfer integrated interface (5) is provided between the deep cold tank (11) and the intermediate cold tank (12) for transferring residual cold, and the intermediate cold tank (12) and the shallow cold tank (13) are commonly connected to a supplementary cold heat exchanger (6); the intermediate cold tank (12) and the shallow cold tank (13) are both wrapped with an aerogel insulation layer (7); the deep cold tank (11) has a cold storage temperature of -10 to -5°C and is used to store base load cold capacity; the intermediate cold tank (12) has a cold storage temperature of 0 to 4°C and is used to store conventional operation cold capacity; the shallow cold tank (13) has a cold storage temperature of 4 to 8°C and is used to store terminal adjustment cold capacity; An intelligent prediction module (2) is used to obtain park meteorological data, building data and historical load data, and output the park's load curve and load change rate for the next 72 hours through a preset load prediction model; the load prediction model is an LSTM neural network model obtained by iterative training of historical data; The optimization control module (3) is used to obtain the electricity price policy of the park to determine the real-time electricity price of the park, collect the real-time cold storage rate of the three-stage cold storage tank group (1), and calculate the global priority index P through a preset index calculation formula based on the real-time electricity price of the park, the real-time cold storage rate of the three-stage cold storage tank group (1) and the load change rate; The cold storage execution unit (4) is configured to perform the following operations according to the global priority index P: When P<0.4, the cryogenic tank (11) is started to store cold, and the intermediate cooling tank (12) simultaneously absorbs the residual cold at the interface of the cryogenic tank (11); When 0.4≤P<0.7, the intercooler (12) is started to store cold; When P≥0.7, the cooling capacity of the shallow cooling tank (13) is released, and when the cooling capacity of the shallow cooling tank (13) is insufficient, the intermediate cooling tank (12) is started to supplement the cooling capacity; The index calculation formula is specifically: P=0.6×C norm +0.3×R s +0.1×V q ; Among them, C norm is the normalized electricity price, C t is the real-time electricity price of the park, C max and C min are the maximum and minimum values ​​of the current electricity price range of the park; R s is the real-time cold storage rate of the three-stage cold storage tank group (1), Q stroed is the real-time cold storage capacity of the three-stage cold storage tank group (1), Q max is the maximum cold storage capacity of the three-stage cold storage tank group (1); V q The load change rate represents the fluctuation speed of the user's cooling load. A positive value indicates an increase in load, while a negative value indicates a decrease in load. When the |V q When |≥15% / h, the P value weight is automatically adjusted to: P=0.55×C norm +0.3×R s +0.15×V q ; And when P≥0.65, start the shallow cooling tank (13) 2 hours in advance to store cold; The heat transfer integrated interface (5) specifically comprises a titanium alloy grid structure (112) arranged on the outer wall of the cryogenic tank (11) and an aluminum-magnesium alloy layer (122) arranged on the inner wall of the intermediate cooling tank (12), and thermal conductive silicone grease (51) is filled between the titanium alloy grid structure (112) and the aluminum-magnesium alloy layer (122) for coupling; A semiconductor power generation module (52) is further provided between the titanium alloy grid structure (112) and the aluminum-magnesium alloy layer (122), and a power generation sheet of the semiconductor power generation module (52) is embedded in a recess of the titanium alloy grid. A cold surface of the power generation sheet is in direct contact with a base layer in the recess of the titanium alloy grid structure (112), and a hot surface is coupled to the aluminum-magnesium alloy layer (122) via thermally conductive silicone.

2. The district cooling system based on a cold storage tank according to claim 1, characterized in that: The outer wall of the deep cooling tank (11) adopts a stainless steel base layer (111), and the stainless steel base layer (111) is S30408 ​​austenitic stainless steel with a thickness of 8-12 mm; the inner wall of the intermediate cooling tank (12) adopts a low-alloy high-strength steel base layer (121), and the outer walls of the intermediate cooling tank (12) and the shallow cooling tank (13) both adopt a composite structure of a carbon steel base layer (131) and a polyurethane foam insulation layer (132), and the density of the polyurethane foam insulation layer (132) is 30-50 kg / m 3 , closed cell rate ≥95%.

3. The district cooling system based on a cold storage tank according to claim 2, characterized in that: The deep cooling tank (11) contains ice slurry cold storage medium, the ice crystal volume fraction of the ice slurry is 20%-40%, and the average particle size of the ice crystals is ≤500μm; the intermediate cooling tank (12) contains ethylene glycol aqueous solution, the mass concentration of the ethylene glycol aqueous solution is 20%-30%, and the freezing point is ≤-10°C; the shallow cooling tank (13) contains paraffin-based phase change material, and its phase change temperature is 5 degrees Celsius.

4. The district cooling system based on a cold storage tank according to claim 1, characterized in that: Microgrooves (113) are provided on the surface of the titanium alloy grid structure (112), wherein the depth of the microgrooves (113) is 0.2-0.5 mm, the width is 0.3-0.8 mm, and the spacing is 1-3 mm; microchannels (123) are provided on the inner surface of the aluminum-magnesium alloy layer (122), wherein the depth of the microchannels (123) is 0.3-0.6 mm, the width is 0.5-1.0 mm, and the spacing is 2-4 mm; the microgrooves (113) and the microchannels (123) are staggered.

5. The district cooling system based on a cold storage tank according to claim 1, characterized in that: The aerogel thermal insulation layer (7) comprises a first SiO2 aerogel layer (71), a carbon fiber grid reinforcement layer (72), and a second SiO2 aerogel layer (73) which are sequentially arranged, wherein the density of the first SiO2 aerogel layer (71) and the second SiO2 aerogel layer (73) is 150-200 kg / m 3 , thermal conductivity ≤ 0.018W / (m·K), the surface density of the carbon fiber grid reinforcement layer (72) is 200-300g / m 2 .

6. The district cooling system based on a cold storage tank according to claim 1, characterized in that: When the cooling capacity of the shallow cooling tank (13) is insufficient, starting the intermediate cooling tank (12) to supplement the cooling specifically comprises the following steps: The optimization control module (3) collects the cold storage rate N of the shallow cooling tank (13) in real time q And the global priority index P, when P ≥ 0.7 and N q When the temperature is less than the preset supplementary cooling threshold, the supplementary cooling program is started; Controlling a pre-set ethylene glycol aqueous solution circulation pump to send the ethylene glycol aqueous solution in the intermediate cooling tank (12) into the supplementary cooling heat exchanger (6) for circulation and preheating for 10 minutes, thereby reducing the temperature of the pipes in the supplementary cooling heat exchanger (6); The ethylene glycol aqueous solution in the intermediate cooling tank (12) is sent to the supplementary cooling heat exchanger (6) and the terminal circuit of the shallow cooling tank (13) for heat exchange; When P < 0.6 and N q When the temperature is greater than the preset cold storage threshold, the cooling program is terminated normally; When supplementary cooling lasts for more than 2 hours and the cold storage rate of the shallow cooling tank (13) is still less than the preset supplementary cooling threshold, the deep cooling tank (11) is started to store cold and supplementary cooling is performed on the intermediate cooling tank (12) through the integrated heat transfer interface (5), and a fault alarm is issued at the same time.

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