Container interior temperature control method and system based on phase change refrigeration device

Abstract

The invention relates to the technical field of temperature control, and particularly discloses a method and system for controlling the temperature in a container based on a phase-change refrigeration device.The method comprises the following steps that S1, a temperature sensor array is arranged to obtain a target temperature, and when the target temperature of any temperature sensor is larger than a preset temperature threshold W1, the temperature sensor array is started; taking the temperature sensor as a target sensor; s2, the phase change refrigeration device is controlled to start a cooling nozzle closest to the target sensor, a refrigerant is sprayed, the refrigerant is subjected to phase change, and environment heat is absorbed; and S3, obtaining the starting time point of the cooling nozzle, setting a monitoring time period, obtaining a target temperature in real time in the monitoring time period, recording the target temperature as a judgment temperature, and deciding the working state of the cooling nozzle according to the change condition of the judgment temperature. Liquid nitrogen spraying is accurately controlled through multi-point real-time monitoring and PID, a local heat source can be rapidly restrained, energy consumption is reduced, the temperature of the whole container is kept uniform and stable, and therefore the quality safety of goods is comprehensively guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of temperature control, and in particular to a method and system for controlling the temperature in a container based on a phase change refrigeration device. Background Art

[0002] To keep electronics, seafood, and other cargo inside containers within a suitable temperature range, a common measure is to install refrigeration and air conditioning systems. Here's how it works: Under the pressure of a compressor, the gaseous refrigerant is converted into a high-temperature, high-pressure gas. After being transported through pipelines, the refrigerant reaches the condenser, where it cools and becomes a medium-temperature, high-pressure liquid. The expansion valve then acts to reduce the pressure, turning the refrigerant into a low-temperature, low-pressure gas-liquid mixture. The evaporator then absorbs heat from the air and vaporizes, thereby lowering the temperature inside the container. Finally, the vaporized refrigerant reenters the compressor for the next refrigeration cycle.

[0003] However, in order to ensure that the temperature inside the traditional container does not exceed the preset temperature value, the installation of refrigeration and air-conditioning devices has the following technical disadvantages: 1) The installation of refrigeration and air-conditioning requires an additional power supply device. The compressor, evaporator, etc. of the refrigeration and air-conditioning device consume a lot of electricity, so a power supply device needs to be installed, and its installation cost and use cost are extremely high; 2) The installation of refrigeration and air-conditioning occupies the storage space inside the container. The compressor, evaporator, power supply device, etc. of the refrigeration and air-conditioning device all require installation space provided by the container, resulting in the squeezing of the cargo storage space inside the container; 3) The refrigeration power is low and it is difficult to meet the requirements of an environment with drastic temperature changes. When maritime transportation encounters extreme convective weather, it may encounter a scenario where the ambient temperature changes drastically. Due to the large internal space of the container and the limited refrigeration power of the air-conditioning, it takes a long time for the air-conditioning refrigeration device to reach the preset temperature after working at full load. Summary of the Invention

[0004] The object of the present invention is to provide a method and system for controlling the temperature in a container based on a phase change refrigeration device to solve the above technical problems.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for controlling temperature in a container based on a phase change refrigeration device comprises the following steps:

[0007] S1: Set up a temperature sensor array to obtain a target temperature. The target temperature represents the temperature inside the container. When the target temperature of any temperature sensor is greater than a preset temperature threshold W1, the temperature sensor is used as the target sensor.

[0008] S2: Control the phase change refrigeration device to open the cooling nozzle closest to the target sensor, spraying refrigerant, which undergoes phase change and absorbs ambient heat;

[0009] S3: Get the time point t0 when the cooling nozzle is turned on, set the monitoring period [t0, t0+t1], t1 represents the preset duration, obtain the target temperature in real time during the monitoring period, record it as the judgment temperature, and decide the working status of the cooling nozzle based on the change of the judgment temperature.

[0010] As a further solution of the present invention: before turning on the cooling nozzle, the method further comprises:

[0011] Get the time point T0 when the target temperature is greater than the temperature threshold W1, and set the judgment period [T0-t1, T0];

[0012] Draw a curve showing the target temperature changes over time within the judgment period. Draw a straight line passing through (0, W1-W0) and parallel to the x-axis as a reference line. W0 represents the preset temperature value.

[0013] The proportion of the domain of the portion above the reference line on the statistical curve to the judgment period. If the proportion is less than 0.3, the cooling nozzle is not turned on.

[0014] As a further solution of the present invention: the temperature sensors are located at preset positions, the number of the temperature sensors is proportional to the volume of the container, and the distance between the temperature sensors is a set value.

[0015] As a further solution of the present invention: the refrigerant is liquid nitrogen.

[0016] As a further solution of the present invention: determining the working state of the cooling nozzle includes:

[0017] Calculating the mean A1 and variance A2 of the determination temperature;

[0018] When the average value A1 is greater than the temperature threshold W1, executing step S2;

[0019] When the mean A1 is less than or equal to the temperature threshold W1 and the variance A2 is greater than the preset variance threshold, executing step S2;

[0020] When the mean A1 is less than or equal to the temperature threshold W1 and the variance A2 is less than or equal to the preset variance threshold, the cooling valve is closed and the spraying of the refrigerant is stopped.

[0021] As a further solution of the present invention: controlling the phase change refrigeration device to open the cooling nozzle closest to the target sensor includes: combining the curve of the target temperature changing with time within the judgment period, and controlling the valve opening of the cooling nozzle through a PID control algorithm to control the spraying amount of the refrigerant.

[0022] A temperature control system in a container based on a phase change refrigeration device, comprising:

[0023] Acquisition module: Set up a temperature sensor array to obtain the target temperature. The target temperature represents the temperature inside the container. When the target temperature of any temperature sensor is greater than the preset temperature threshold W1, the temperature sensor is used as the target sensor.

[0024] Control module: Controls the phase change refrigeration device to open the cooling nozzle closest to the target sensor, sprays refrigerant, and the refrigerant undergoes phase change to absorb ambient heat.

[0025] Decision module: obtain the time point t0 when the cooling nozzle is turned on, set the monitoring period [t0, t0+t1], t1 represents the preset duration, obtain the target temperature in real time during the monitoring period, record it as the judgment temperature, and decide the working status of the cooling nozzle based on the change of the judgment temperature.

[0026] The beneficial effects of the present invention are as follows:

[0027] 1) Low cost. Containers with built-in phase change refrigeration devices do not require additional air conditioning and power supply equipment, significantly reducing costs;

[0028] 2) Increased cargo space. Containers with built-in phase change refrigeration devices do not require additional compressors, evaporators, power supply devices, etc., which saves internal space and increases the cargo capacity of the container;

[0029] 3) Excellent transient cooling effect. Phase change transient cooling is effective and meets the needs of environments with drastic temperature fluctuations. Because the phase change medium undergoes a phase change instantly, it quickly absorbs the surrounding heat, thus achieving rapid cooling, allowing the temperature inside the chamber to quickly reach the preset temperature and prevent the ambient temperature from fluctuating beyond the threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below with reference to the accompanying drawings.

[0031] Figure 1 This is a flow chart of a method for controlling temperature in a container based on a phase change refrigeration device according to the present invention;

[0032] Figure 2 This is a schematic diagram of the working principle of a method for controlling temperature in a container based on a phase change refrigeration device according to the present invention;

[0033] Figure 3 It is a control principle diagram of the phase change refrigeration device of the present invention. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0035] See also Figure 1 As shown, the present invention is a method for controlling the temperature in a container based on a phase change refrigeration device, comprising the following steps:

[0036] S1: The temperature sensor array is evenly distributed on the top, side walls, and cargo gaps inside the container. It is connected to the controller via a bus to form a closed-loop data acquisition network. The controller polls each sensor according to a fixed refresh cycle and records the target temperature value measured in real time. When the sensor data at a certain location is judged to be higher than the threshold W1 through the comparison instruction set by the program, the controller immediately marks the sensor as "overtemperature" in the memory and writes its index to the target list. At the same time, the timestamp recording logic is triggered to save the specific time of the first overtemperature. The system then defines this sensor as the current target sensor for subsequent scheduling. For example, when the sensor near the top of the container door first detects a temperature increase due to the infiltration of hot air from the outside, the controller will identify it as the target sensor. Other sensors that are still within the normal range will continue to maintain the monitoring state and wait for the next polling judgment.

[0037] It is understandable that this allows the system to only respond to real and persistent local heat sources.

[0038] Rapid response avoids missing opportunities for early intervention due to a lack of significant overall average temperature increases. It also prevents subsequent refrigeration operations from being falsely triggered due to transient noise or brief disturbances, thereby reducing unnecessary refrigerant consumption and extending equipment life. This plays a fundamental role in achieving refined and energy-saving full-tank temperature control, further ensuring temperature stability and quality safety of cargo during transportation.

[0039] In a preferred embodiment of the present invention, during the container design phase, modeling software is first used to calculate the internal effective volume and a preset sensor density coefficient is called to automatically generate the required number of sensors. Subsequently, a regular grid is drawn in the three-dimensional model, with each intersection as a potential installation site. Engineers select nodes on the top, bottom, four corners, and several longitudinal sections based on common cargo stacking patterns and airflow directions, and drill holes to install sensors, ensuring that adjacent measuring points maintain a uniform center distance in the horizontal and vertical directions. For example, after determining that a measuring point is placed every half a meter, temperature sensors of the same model are continuously installed in the corresponding beam grooves. The leads are then passed through a corrugated pipe, merged into the wire duct, connected to the control unit, and numbered and registered, thereby obtaining a temperature monitoring network with automatic matching of quantity and volume and consistent spacing.

[0040] Notably, this arrangement ensures that the temperature distribution is captured with the same resolution regardless of container size, eliminating blind spots and avoiding hardware redundancy. The uniform spacing facilitates the algorithm's rapid calculation of the geometric relationship between the measurement points and the sprinklers, enabling it to execute the closest sprinkler strategy. This improves the timeliness and accuracy of localized cooling, reduces system costs and maintenance complexity, and provides a reliable foundation for stable temperature control throughout the entire transport cycle.

[0041] S2: After receiving the over-temperature mark of the target sensor, the control system immediately calls the nozzle coordinate table stored in the memory, selects the nozzle closest to the sensor according to the geometric distance algorithm, and then sends an opening pulse to the solenoid valve corresponding to the nozzle through the field bus. At the same time, it issues an opening instruction to the proportional valve to set the initial flow rate. The liquid refrigerant is then pushed along the pipeline to the nozzle and sprayed into the air layer near the sensor in the form of fine mist. During the jet diffusion process, it quickly vaporizes and absorbs the surrounding heat to achieve local cooling. The control system continuously reads the data of the flow meter and pressure sensor and performs periodic adjustments in combination with the feedback of the target sensor. For example, after the first pulse ends, it adjusts the temperature based on the temperature drop rate.

[0042] Decide whether to enter intermittent spraying mode or maintain continuous spraying, so that the sprinkler head always keeps the output state matching the real-time demand;

[0043] It's important to note that this approach allows the refrigerant to be concentrated where the sudden heat rise actually occurs, rather than being sprayed throughout the entire container. This fundamentally reduces unnecessary cooling waste and the risk of frost. Hot spots are quickly cooled, preventing the localized high temperature from spreading to other areas, indirectly protecting goods at normal temperatures. Furthermore, the one-to-one mapping strategy between target nozzles and sensors simplifies the control logic, making it easier to maintain and expand. Ultimately, this helps the system achieve long-term stable in-box temperature control with lower energy consumption while ensuring cargo quality.

[0044] It is worth noting that the control of the phase change refrigeration device to open the cooling nozzle closest to the target sensor includes:

[0045] First, the real-time temperature curve within the judgment cycle is imported into the calculation cache. The end value of the most recent refresh cycle is used as the current feedback value, and the set target temperature threshold is used as the given value. Then, the temperature control-specific PID module is called to calculate the combined error of the proportional, integral, and differential terms within the same millisecond. The result is converted into a percentage valve opening and sent to the nozzle valve driver. After receiving the command, the driver immediately adjusts the stepper motor angle to change the flow cross-section of the valve port. The liquid refrigerant flow rate changes accordingly and affects the spray atomization intensity. The controller maintains a millisecond-level loop, each time substituting the latest temperature difference into the PID formula to correct the valve opening in real time. For example, if the temperature in the box suddenly rises, the proportional term instantly increases the opening to cause rapid cooling. When the temperature approaches the threshold and small fluctuations occur due to external disturbances, the differential term fine-tunes the valve to avoid overshoot. In the case of slow heat accumulation over a long period of time, the integral term gradually increases the opening to ensure that steady-state errors are eliminated.

[0046] The use of the PID algorithm enables the nozzle valve to have sufficient response speed when facing rapid temperature changes and to suppress temperature fluctuations caused by over-adjustment. Its proportional link provides instant cooling capability, the integral link eliminates long-term deviations, and the differential link reduces the risk of oscillation, thereby maintaining a dynamic match between the refrigerant spray volume and the actual heat load, achieving accurate and smooth cooling of hot spots in the box, reducing waste and ensuring the temperature stability of the goods throughout the transportation process.

[0047] Another preferred embodiment of the present invention further comprises:

[0048] When the real-time temperature of a certain measuring point crosses the threshold W1 for the first time, the current time is immediately recorded as T0, and the historical data segment of length t1 is read back in the cache database to form the time interval [T0-t1, T0]. The built-in drawing function is then called to connect the points of this sampling data in chronological order to generate a temperature change curve. A horizontal baseline is then drawn in the same coordinate system, parallel to the time axis, and with the vertical coordinate of W1 minus the preset temperature W0. After the curve and the baseline are superimposed, the system uses the integration method to scan the entire time axis, calculates the total length of the interval where the curve falls above the baseline, and performs a ratio operation with the total duration of the judgment cycle. If the calculated ratio is lower than the threshold of 0.3, the corresponding nozzle opening instruction is directly skipped in the decision logic, and the measuring point is restored to the normal monitoring state. For example, when a gust of convection airflow briefly blows the hot box door, causing the temperature to rise rapidly but then quickly fall back, the ratio will be calculated as lower than the threshold, and the system will not enter the cooling process.

[0049] It is important to note that this adds a layer of robustness screening in the time dimension to the temperature signal before the nozzle is activated. This can distinguish occasional instantaneous fluctuations from truly continuous heat accumulation, avoiding the waste of resources caused by unnecessary liquid nitrogen spraying triggered by short-term noise, and ensuring that the cooling process can be started in time once the temperature rise is sustained. Overall, the startup decision of local refrigeration is both sensitive and robust, thereby ensuring that thermal anomalies in the box are quickly suppressed while reducing the energy consumption and wear of the entire device, providing reliable protection for temperature stability during long-term transportation.

[0050] It will be appreciated that the refrigerant is preferably liquid nitrogen;

[0051] S3: Obtain the time t0 when the cooling nozzle is turned on, set the monitoring period [t0, t0+t1], where t1 represents the preset duration, obtain the target temperature in real time during the monitoring period, record it as the judgment temperature, and decide the working state of the cooling nozzle based on the change of the judgment temperature;

[0052] The controller writes the system clock value to the variable t0 in the same millisecond when it issues the opening command to the target nozzle, and then automatically generates the monitoring window [t0, t0+t1] according to the preset parameter t1 and adds the high-priority sampling task to the scheduling list. This task polls the target sensor at a fixed beat, writes the sampled temperature into the ring buffer in real time and calls the judgment temperature sequence.

[0053] The calculation module calculates the latest mean and variance and passes them to the decision logic to continuously update the opening and closing of the nozzle and the opening of the valve;

[0054] It is important to note that establishing a controlled monitoring window immediately after the nozzle is activated and using real-time statistical results to drive the continuation or cessation of spraying can accurately match the refrigerant delivery to the actual heat load. This not only avoids the waste caused by prolonged overspray due to a single overtemperature, but also prevents secondary temperature rise caused by premature spraying cessation. The entire process can dynamically balance energy consumption and temperature requirements without manual intervention, providing continuous protection for cargo quality and safety, and reducing the pressure on equipment operation and maintenance.

[0055] In a preferred embodiment of the present invention, determining the working state of the cooling nozzle includes:

[0056] After each refresh cycle, the internal mathematical library is called to normalize and accumulate the judgment temperature sequence in the monitoring window and divide it by the number of sampling points to obtain the mean value A1. At the same time, the single-pass scan algorithm is used to accumulate the square difference in real time and divide it by the number of samples to obtain the variance A2. Then, the decision branch is entered: if A1 is higher than the threshold W1, the spraying subroutine is immediately re-called to maintain or increase the flow rate. If A1 is not higher than W1 but A2 still fluctuates significantly and exceeds the variance threshold, it is determined that the temperature field has not yet stabilized and the spraying subroutine is continued. If A1 is below the threshold and A2 is also lower than or equal to the variance threshold, it means that the local heat load is suppressed, and a valve closing command is sent to the solenoid valve. At the same time, the valve opening variable is reset to zero and the spraying stop time is recorded for subsequent temperature rise tracking.

[0057] The dual-indicator judgment method based on mean and variance takes into account both the absolute temperature level and the temperature fluctuation amplitude. This prevents the system from prematurely stopping spraying due to drastic fluctuations after a single high temperature point is rapidly lowered, nor does it continue to spray meaninglessly when the overall temperature has returned to a safe zone and fluctuations have stabilized. This fundamentally achieves a dynamic balance between cooling capacity and heat load, effectively reducing refrigerant waste and the risk of frosting and local overcooling, providing adaptive control support for long-term uniform and stable temperature throughout the entire cabinet.

[0058] A temperature control system in a container based on a phase change refrigeration device, comprising:

[0059] Acquisition module: Set up a temperature sensor array to obtain the target temperature. The target temperature represents the temperature inside the container. When the target temperature of any temperature sensor is greater than the preset temperature threshold W1, the temperature sensor is used as the target sensor.

[0060] Control module: Controls the phase change refrigeration device to open the cooling nozzle closest to the target sensor, sprays refrigerant, and the refrigerant undergoes phase change to absorb ambient heat.

[0061] Decision module: obtains the time point t0 when the cooling nozzle is turned on, sets the monitoring period [t0, t0+t1], where t1 represents the preset duration, obtains the target temperature in real time during the monitoring period, records it as the judgment temperature, and decides the working status of the cooling nozzle based on the change of the judgment temperature;

[0062] See also Figure 2 As shown, the working principle of the temperature control method in a container based on a phase change refrigeration device of the present invention is as follows:

[0063] The cold source system 202 provides refrigerant for the phase change refrigeration device. One refrigerant provided by the present invention is liquid nitrogen. A safety valve 203 is provided to prevent abnormal increases in pipeline pressure. A pump source pipeline 204 connects the cold source system 202 and the regulating valve 205, used to transport the phase change medium. The regulating valve 205 is used to adjust the flow rate of the refrigerant. The valve island 206 controls the on / off supply of refrigerant to cooling nozzles 1 208, 210, 312, ..., and 214. The phase change refrigeration controller 207 collects and analyzes data from various sensors and controls the operation and output of the valve island 206 and regulating valve 205. Cooling nozzles 1 208, 210, 312, ..., and 214 are distributed within the container. After being ejected from the cooling nozzles, the phase change medium changes from liquid to gas, absorbing heat from the surrounding environment, thereby lowering the ambient temperature. Temperature sensor 1 209, temperature sensor 2 211, temperature sensor 3 213, ..., and temperature sensor 215 are used to detect the temperature values ​​at the corresponding local locations of the cooling nozzles. Pre-valve pipeline 216 connects control valve 205 and valve island 206 for transporting phase-change medium. Post-valve pipeline 217 connects valve island 206 and cooling nozzle 1 208, cooling nozzle 2 210, cooling nozzle 3 212, ..., and cooling nozzle 214 for transporting phase-change medium. Control valve control circuit 218 connects control valve 205 and phase-change refrigeration controller 207 for transmitting control signals between control valve 205 and phase-change refrigeration controller 207. Valve island control circuit 219 connects valve island 206 and phase-change refrigeration controller 207 for transmitting control signals between valve island 206 and phase-change refrigeration controller 207. Temperature sensor control circuit 220, temperature sensor three control circuit 221, temperature sensor two control circuit 222, temperature sensor one control circuit 223

[0064] It is connected to the phase change refrigeration controller 207 and is used to transmit the temperature data collected by each temperature sensor. The online monitoring module 224 is used to display the status of the container phase change refrigeration device.

[0065] See also Figure 3 As shown, the control principle diagram of the phase change refrigeration device of the present invention is as follows:

[0066] The control system consists of a valve island control module 401, a phase-change cooling controller 402, a regulating valve control module 403, a fuse 404, a temperature detection module 405, a valve island position detection module 406, a fuse 407, a regulating valve position detection module 408, an online monitoring module 409, and a cold source detector 410. The solenoid switch Y01 in the valve island control module 401 controls the on / off of cooling nozzle 1, the solenoid switch Y02 in the valve island control module 401 controls the on / off of cooling nozzle 2, the solenoid switch Y03 in the valve island control module 401 controls the on / off of cooling nozzle 3, and so on. The solenoid switch YN in the valve island control module 401 controls the on / off of cooling nozzle N. The solenoid switches Y01, Y02, ..., and YN of the valve island control module 401 are connected to pins F01, F02, F03, ..., and FN of the phase-change cooling controller 402, respectively. Each solenoid switch of the valve island control module 401 is controlled by the phase-change cooling controller 402. Fuses 404 and 407 are used to prevent current overloads from damaging the sensors in each branch line. The proportional solenoid YM of the regulating valve control module 403 is used to control the flow rate of the phase-change medium supply and is connected to pin M of the phase-change cooling controller 402, thereby being controlled by the phase-change cooling controller 402. The temperature detection module 405's temperature sensors S01, S02, S03, ..., and SN are connected to the CAN2 port (CAN_2H / CAN_2L) of the phase-change cooling controller 402, reporting real-time temperature values ​​to the phase-change cooling controller 402. The valve island position detection module 406 , the regulating valve position detection module 408 , the online monitoring module 409 , and the cold source detector 410 are connected to the CAN1 port (CAN_1H / CAN_1L) of the phase change refrigeration controller 402 .

[0067] The above is a detailed description of an embodiment of the present invention. However, the content described is only a preferred embodiment of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for controlling the temperature inside a container based on a phase change refrigeration device, characterized in that: The following steps are involved: S1: Set up a temperature sensor array to obtain a target temperature. The target temperature represents the temperature inside the container. When the target temperature of any temperature sensor is greater than a preset temperature threshold W1, the temperature sensor is used as the target sensor. S2: Control the phase change refrigeration device to open the cooling nozzle closest to the target sensor, spraying refrigerant, which undergoes phase change and absorbs ambient heat; S3: Get the time point t0 when the cooling nozzle is turned on, set the monitoring period [t0, t0+t1], t1 represents the preset duration, obtain the target temperature in real time during the monitoring period, record it as the judgment temperature, and decide the working status of the cooling nozzle based on the change of the judgment temperature.

2. The method for controlling the temperature in a container based on a phase change refrigeration device according to claim 1, characterized in that: Before turning on the cooling nozzle, the following steps must also be performed: Get the time point T0 when the target temperature is greater than the temperature threshold W1, and set the judgment period [T0-t1, T0]; Draw a curve showing the target temperature changes over time within the judgment period. Draw a straight line passing through (0, W1-W0) and parallel to the x-axis as a reference line. W0 represents the preset temperature value. The proportion of the domain of the portion above the reference line on the statistical curve to the judgment period. If the proportion is less than 0.3, the cooling nozzle is not turned on.

3. The method for controlling the temperature in a container based on a phase change refrigeration device according to claim 1, characterized in that: The temperature sensors are located at preset positions, the number of temperature sensors is proportional to the volume of the container, and the distance between the temperature sensors is a set value.

4. The method for controlling the temperature in a container based on a phase change refrigeration device according to claim 1, characterized in that: The refrigerant is liquid nitrogen.

5. The method for controlling the temperature in a container based on a phase change refrigeration device according to claim 1, characterized in that: The working status of the cooling nozzle is determined by: Calculating the mean A1 and variance A2 of the determination temperature; When the average value A1 is greater than the temperature threshold W1, executing step S2; When the mean A1 is less than or equal to the temperature threshold W1 and the variance A2 is greater than the preset variance threshold, executing step S2; When the mean A1 is less than or equal to the temperature threshold W1 and the variance A2 is less than or equal to the preset variance threshold, the cooling valve is closed and the spraying of the refrigerant is stopped.

6. The method for controlling temperature in a container based on a phase change refrigeration device according to claim 2, characterized in that: Controlling the phase change refrigeration device to open the cooling nozzle closest to the target sensor includes: combining a curve of the target temperature changing with time within a judgment period, controlling the valve opening of the cooling nozzle through a PID control algorithm to control the spraying amount of the refrigerant.

7. A temperature control system in a container based on a phase change refrigeration device, characterized in that: include: Acquisition module: Set up a temperature sensor array to obtain the target temperature. The target temperature represents the temperature inside the container. When the target temperature of any temperature sensor is greater than the preset temperature threshold W1, the temperature sensor is used as the target sensor. Control module: Controls the phase change refrigeration device to open the cooling nozzle closest to the target sensor, sprays refrigerant, and the refrigerant undergoes phase change to absorb ambient heat. Decision module: obtain the time point t0 when the cooling nozzle is turned on, set the monitoring period [t0, t0+t1], t1 represents the preset duration, obtain the target temperature in real time during the monitoring period, record it as the judgment temperature, and decide the working status of the cooling nozzle based on the change of the judgment temperature.

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