System for actively maintaining temperature of sampling cylinder based on alcohol-dry ice circulating refrigeration

Abstract

The invention relates to a deep sea resource exploration technology, and aims to provide a system for actively maintaining the temperature of a sampling cylinder based on alcohol-dry ice circulating refrigeration. The system comprises a heat preservation sampling barrel, an alcohol dry ice barrel, a gear pump, a motor cabin, an electronic cabin, a battery and a plurality of temperature sensors, the heat preservation sampling barrel comprises a sampling barrel and a heat preservation barrel, a separation cavity of the sampling barrel and the heat preservation barrel is filled with water and provided with a heat exchange coil, the gear pump, the heat exchange coil and the alcohol dry ice barrel are connected through a pipeline to form a coolant circulation loop, and the alcohol dry ice barrel is filled with an alcohol dry ice mixture; temperature sensors are respectively arranged in the sampling barrel, the separation cavity, the alcohol dry ice barrel and the seawater, and the controller calls the BP neural network module for calculation and sends a control signal to the motor, so that the temperature of the sampling barrel is actively and accurately maintained. The temperature stability of the sampling barrel is ensured in a circulating refrigeration mode, so that the biological activity and the morphological integrity of the sampling barrel are protected, and the survival rate is increased.

Description

Technical Field

[0001] The present invention relates to the field of deep - sea resource exploration, and particularly to an active system for maintaining the temperature of a sampling cylinder based on alcohol - dry ice cycle refrigeration. This system can meet the requirements of heat preservation and pressure maintenance during the sampling process of deep - sea animals. Background Art

[0002] Ecosystems such as deep - sea cold seeps, hydrothermal vents, seamounts, whale falls, and abysses are rich in unique biological resources. These biological resources in extreme environments are of great value for researching fields such as the origin of life, biodiversity, adaptive evolution, extraction of active substances, and new drug development. However, due to deep - sea animals' long - term adaptation to extreme conditions such as high pressure and low temperature, how to achieve in - vivo sampling poses a huge challenge to experimental research.

[0003] Currently, in the field of high - fidelity sampling technology for deep - sea animals, although domestic and foreign scientists have made significant breakthroughs in pressure maintenance. For example, patent CN1111092138 has developed a deep - sea animal pressure - maintaining sampler with a two - way piston sealing function and successfully collected pressure - maintained samples in extreme deep - sea environments such as the Mariana Trench. However, even this sampler still has significant defects in temperature control and lacks an efficient and stable heat - preservation mechanism.

[0004] To achieve high - fidelity sampling of deep - sea animals and ensure that various samples can always maintain their in - situ characteristics throughout the process from collection to laboratory analysis, more stringent requirements are imposed on the fidelity performance of the sampler, thus precise control of the internal temperature of the sample cylinder is required. Existing temperature - control technologies for deep - sea sampling are mainly divided into passive heat preservation and active heat preservation. Passive heat preservation means wrapping heat - insulating materials outside the sampling cylinder, and this heat - preservation method can only temporarily relieve the temperature rise inside the sample cylinder. Active heat preservation is mainly applied in the freezing coring process of natural gas hydrate cores. However, this refrigeration technology mainly achieves cooling through the phase - change endothermic effect of low - temperature phase - change liquids, and its function is to quickly freeze the core and does not require accurate control of the temperature inside the sample cylinder during the sampling process.

[0005] Therefore, the present invention aims to provide a device that can actively and precisely control the temperature to maintain the temperature required for the survival of deep - sea animals in response to the above - mentioned problems. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide an active system for maintaining the temperature of a sampling cylinder based on alcohol - dry ice cycle refrigeration.

[0007] To solve the technical problem, the solution of the present invention is:

[0008] Provided is a system for actively maintaining the temperature of a sampling cylinder based on alcohol-dry ice cycle refrigeration, which is characterized by comprising a heat-insulating sampling cylinder for deep-sea animal sampling, an alcohol-dry ice cylinder, a gear pump, a motor cabin, an electronic cabin, a battery and a plurality of temperature sensors; wherein,

[0009] The heat-insulating sampling cylinder includes a sampling cylinder with a single-end closed and a heat-insulating cylinder with a heat-insulating interlayer. The former is located inside the latter and arranged coaxially, maintaining a radial distance to form an annular cavity in cross-section; water is filled in the cavity and a heat exchange coil is arranged. A coolant circulation loop is formed by connecting the gear pump, the heat exchange coil and the alcohol-dry ice cylinder with pipelines. An alcohol-dry ice mixture is filled in the alcohol-dry ice cylinder, and the temperature of the sampling cylinder is maintained stable by adjusting the water temperature in the cavity; the gear pump is connected to a motor arranged in the motor cabin through a transmission mechanism, and the motor is respectively connected to the battery and a control board arranged in the electronic cabin through cables;

[0010] There are at least four of the temperature sensors, which are respectively arranged in the sampling cylinder, the cavity, the alcohol-dry ice cylinder and seawater. Each temperature sensor is respectively connected to a data acquisition card in the electronic cabin through a cable, and the data acquisition card is electrically connected to the control board; a memory and a controller are arranged on the control board, and a BP neural network module is built in the memory; the BP neural network module includes an input layer, a hidden layer and an output layer. The input layer is used to receive four key parameters, namely the external seawater temperature, the seawater temperature change rate, the internal temperature of the sampling cylinder and the sampling cylinder temperature change rate. The hidden layer is used to process the input data and extract features, and the output layer is used to output the rotational speed of the gear pump as the calculation result; the controller is used to call the BP neural network module for calculation and send a control signal to the motor, finally realizing the active and precise maintenance of the temperature of the sampling cylinder.

[0011] As a preferred solution of the present invention, the heat-insulating cylinder includes a cylinder body, a front end cover and a rear end cover. The two end covers are hermetically installed with the cylinder body through sealing rings and bolts; the sampling cylinder is fixedly installed between the two end covers of the heat-insulating cylinder, its rear end is closed and a sampling port is provided at the front end; a central through hole is provided on the front end cover of the heat-insulating barrel and is equipped with a detachable circular heat-insulating sleeve, and the heat-insulating sleeve can be embedded into the central through hole and sealed through an annular sealing ring.

[0012] As a preferred solution of the present invention, the inner diameter of the heat-insulating cylinder is 20-30 mm larger than the outer diameter of the sampling cylinder.

[0013] As a preferred solution of the present invention, the alcohol-dry ice cylinder includes a cylinder body, a front end cover and a rear end cover. The front and rear end covers are hermetically installed with the cylinder body through sealing rings and bolts; a pipe joint is provided on the rear end cover or the cylinder body near the rear end cover, and is connected to the heat exchange coil through a pipeline; two pipe joints are provided on the front end cover, and are respectively connected to a leather bag and the input port of the gear pump through pipelines; a one-way pressure relief valve is also provided on the cylinder body.

[0014] As a preferred embodiment of the present invention, the pipeline in the coolant circulation loop is a rigid polyurethane pipe; the heat exchange coil is a copper pipe, which is arranged in a spiral manner between the sampling cylinder and the heat preservation cylinder and does not contact either of them.

[0015] As a preferred embodiment of the present invention, in the alcohol-dry ice mixture, the mass ratio of alcohol to dry ice is 2:1.

[0016] As a preferred embodiment of the present invention, the battery is a 48V water-sealed battery.

[0017] As a preferred embodiment of the present invention, the temperature sensor includes a probe, a hose connector, a pipe connector nut, a silicone hose, and a cable arranged in sequence. The other end of the cable is connected to the electronic cabin through a quick connector; a platinum resistor is arranged inside the shell of the probe as a temperature-sensitive element, and thermal conductive silicone is filled between the shell and the platinum electrode.

[0018] The present invention further improves the method for actively maintaining the temperature of the sampling cylinder by using the aforementioned system, including:

[0019] (1) Build a system for actively maintaining the temperature of the sampling cylinder. Fill water in the partition cavity of the heat preservation sampling cylinder, and fill the alcohol-dry ice mixture in the alcohol-dry ice cylinder;

[0020] (2) Create a deep-water environment for determining the external temperature change rate. Use a sufficient amount of known data as a training set to train the BP neural network module; these known data include the corresponding relationships between the pump speed and various temperature parameters under different temperature environments;

[0021] During the training process, the gradient descent method is used to optimize the weights and biases of the neural network; a regression function is used to calculate the output value from the hidden layer to the output layer, and the deviation is defined as the distance between the output value and the target value; perform error analysis on the output result and the expected result, and modify the weights and thresholds; continuously iterate to update the weights and biases until the deviation meets the requirements or the output result is consistent with the expected result, and complete the training of the neural network model;

[0022] (3) Fix the system for actively maintaining the temperature of the sampling cylinder on the frame of the deep-sea biological sampling device, and use the mother ship to carry it and lower it to the sampling area; first start the motor to drive the gear pump, and use the alcohol-dry ice mixture to cool the water in the partition cavity until it is consistent with the seawater temperature in the sampling area; then use the deep-sea biological sampling device to conduct deep-sea biological sampling, and after sending it into the sampling cylinder, close the inlets of the sampling cylinder and the heat preservation barrel;

[0023] (4) During the process of recovering the deep-sea biological sampling device, multiple temperature sensors are used to continuously monitor and record the temperatures in the sampling cylinder, the isolation chamber, the alcohol-dry ice cylinder, and the seawater. The external seawater temperature, the seawater temperature change rate, the internal temperature of the sampling cylinder, and the sampling cylinder temperature change rate are calculated based on the temperature measurement values, and then used as inputs for the BP neural network module for calculation. According to the output result, a control signal is sent to the motor to adjust the rotation speed of the gear pump, thereby achieving active and precise maintenance of the sampling cylinder temperature.

[0024] As a preferred solution of the present invention, a protection threshold is set based on the in-situ temperature T0 of the seawater environment in the sampling area, and the water temperature T1 in the isolation chamber is monitored at any time during the recovery process of the deep-sea biological sampling device. If T1 rises and reaches or exceeds 115% of T0, the gear pump is forcibly started to quickly cool the water in the isolation chamber; when T1 drops below 85% of T0, the gear pump is forcibly turned off.

[0025] Description of the invention principle:

[0026] 1. Combining with the high-pressure scenario in the deep-sea environment, the present invention innovatively proposes to use pipelines to connect a gear pump, a heat exchange coil, and an alcohol-dry ice cylinder to form a coolant circulation loop, and an alcohol-dry ice mixture is filled in the alcohol-dry ice cylinder. Based on the fact that the alcohol-dry ice mixture can always maintain a liquid-phase circulation under different pressure changes, full-process temperature control can be achieved during the process of recovering the sampling equipment.

[0027] Refrigeration equipment used on land (such as air conditioners, refrigerators, etc.) usually adopts the principle of condensation-evaporation refrigeration. It is necessary to use a compressor to inhale low-temperature and low-pressure refrigerant vapor and compress it into high-temperature and high-pressure vapor; the high-temperature and high-pressure vapor enters the condenser to exchange heat with the cooling medium and is cooled into a liquid refrigerant. The liquid refrigerant passes through an expansion valve and throttles into a low-pressure liquid refrigerant; the low-pressure liquid refrigerant evaporates in the evaporator and absorbs the heat of the surrounding environment, thereby achieving the refrigeration effect. The circulating medium in such refrigeration equipment contains low-pressure gas. If it is necessary to carry out waterproof encapsulation for application scenarios in the deep-sea high-pressure environment (the pressure reaches 100 MPa at a depth of 10,000 meters), it is necessary to consider ensuring the structural strength to avoid the influence of high pressure on the phase transformation of the circulating medium, and a specially enhanced pressurization and pressure-holding system must be configured; this will result in too large wall thicknesses for the condenser tube, the condenser encapsulation shell, etc., making the entire temperature maintenance system extremely large and unable to be applied to the seabed exploration sampling platform with limited loading space.

[0028] Although some researchers have proposed using an alcohol-dry ice mixture as a refrigerant for deep-sea rock sample preservation. However, in this solution, the usage method is to inject a mixture of alcohol and dry ice outside the core after completing deep-sea core sampling, and use the gasification heat absorption of dry ice to quickly freeze the core below 0 degrees, and it is impossible to accurately control the injection amount of the coolant and the sample temperature.

[0029] The chemical property of the temperature of the mixture of dry ice and alcohol is that it always remains at -78°C under low pressure, and the phase change of dry ice generates a large amount of heat absorption. Therefore, this aspect innovatively proposes to use dry ice and alcohol as a cold source, using the heat absorption of dry ice gasification to keep the temperature of alcohol at -78°C, and refrigerating through the circulation of alcohol.

[0030] The present invention proposes to use a dry ice-alcohol mixture with a mass ratio of 2:1 as a refrigerant. Under this ratio condition, the characteristic of dry ice is that it is in a liquid state in an environment above 6 MPa and in a solid state in an environment below 6 MPa. Therefore, when the water depth exceeds 600 m (pressure greater than 6 MPa), dry ice is liquid CO2, and the liquid circulated by the gear pump is a mixture of dry ice and alcohol. In this state, the temperature of dry ice is below -78°C, and 1 kg of dry ice absorbs 1 kJ of heat per 1°C increase. At this time, the seawater temperature is 2 - 4°C, and the refrigeration capacity required to maintain the temperature of the water in the partition chamber unchanged per unit time is small (the required refrigeration capacity is proportional to the temperature difference in the partition chamber), and the heat absorption of dry ice heating is sufficient for refrigeration. When the water depth is less than 600 m (pressure less than 6 MPa), due to being close to the sun, the seawater temperature will rise sharply to 20 - 30°C, and the refrigeration capacity required to be input per unit time is large (the large temperature difference in the partition chamber leads to a large required refrigeration capacity). However, at this time, dry ice is in a solid state, the temperature of the dry ice-alcohol mixture will be maintained at -78°C, and the liquid circulated by the gear pump is alcohol. Relying on the sublimation of dry ice to keep the temperature of alcohol at -78°C, and 1 kg of dry ice gasification absorbs 573.6 kJ of heat, which can provide a greater amount of cold. Therefore, the heat absorption of dry ice in the present invention can provide the refrigeration capacity required to maintain the temperature of the partition chamber. In addition, a one-way valve is provided at the top of the dry ice-alcohol cylinder for the gas generated by the gasification of dry ice to escape to avoid excessive pressure inside the dry ice-alcohol cylinder, and the internal and external pressure balance is formed through the leather bag, greatly reducing the wall thickness required for the pipeline and the dry ice-alcohol cylinder cabin body, and greatly reducing the volume of the device.

[0031] 2. The present invention does not directly use a refrigerant to cool the sampling cylinder, but uses the water in the partition chamber between the heat preservation cylinder and the sampling cylinder as a buffer. Water exhibits a high specific heat capacity when heating or cooling, which means it can absorb or release a large amount of heat with little temperature change. Compared with the method of directly cooling the control target, the temperature fluctuation can be greatly reduced.

[0032] 3. The present invention sets improved temperature sensors in multiple key areas. A platinum resistance is set as a temperature-sensitive element inside the outer shell of the probe head, and thermal conductive silica gel is filled between the outer shell and the platinum electrode; the size of the traditional temperature-sensitive probe head is greatly reduced, and when arranged in the limited space of the sampling cylinder, the partition chamber, and the dry ice-alcohol cylinder, its normal function will not be affected.

[0033] 4. The present invention innovatively proposes to build a pre-trained local BP neural network module in the electronic cabin of the deep-sea biological sampling device; calculate the external seawater temperature, seawater temperature change rate, internal temperature of the sampling cylinder, and sampling cylinder temperature change rate based on the temperature measurement values, and use the computing power of the BP neural network to obtain the rotation speed of the circulation pump, and actively and accurately maintain the temperature of the sampling cylinder through appropriate pre-adjustment.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] 1. The active temperature precise maintenance device proposed by the present invention can ensure the temperature stability during the collection of deep-sea animals and the recovery of the sampler through the alcohol-dry ice circulation refrigeration method. Ensure that the temperature around the deep-sea animals is still effectively simulated and maintained after leaving the natural environment, thereby protecting their biological activity and morphological integrity and improving the survival rate.

[0036] 2. The present invention realizes the regulation of the water pump rotation speed based on the BP neural network. By collecting and analyzing the energy consumption data under different working conditions, and combining the neural network model to deeply mine and analyze the experimental data, a high-precision energy efficiency prediction and optimization model is constructed. This model can automatically adjust the equipment operation parameters according to the changes in the operating environment in real time to reach the best energy efficiency balance point, which is more power-saving than the traditional technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the device of the present invention.

[0038] Figure 2 It is a sectional view of the heat-insulated sampling cylinder.

[0039] Figure 3 It is a mating diagram of the closed structure of the sampling cylinder and the heat-insulating cylinder.

[0040] Figure 4 It is a schematic diagram of the alcohol-dry ice cylinder.

[0041] Figure 5 It is a sectional view of the temperature sensor.

[0042] Figure 6 It is a schematic diagram of the temperature control principle as a safety redundancy.

[0043] Figure 7 It is a schematic diagram of the BP neural network module.

[0044] In the figure, 1 is a heat-insulated sampling cylinder; 1-1 is a heat-insulated cylinder; 1-2 is a sampling cylinder; 1-3 is a front end cover; 1-4 is a cylinder body; 1-5 is a rear end cover; 2 is a gear pump; 3 is an alcohol dry ice cylinder; 3-1 is a rear end cover; 3-2 is a pressure relief valve; 3-3 is a front end cover; 3-4 is a cylinder body; 3-5 is a leather bag; 4 is a temperature sensor; 4-1 is a probe; 4-2 is a hose joint; 4-3 is a pipe joint nut; 4-4 is a silica gel hose; 4-5 is a cable; 5 is a motor compartment. Detailed implementation manners

[0045] The technical solutions of the present invention will be described in detail and clearly below in conjunction with the accompanying drawings. It should be noted that the embodiments described here are only a part of many examples of the present invention, rather than all of them. According to these embodiments of the present invention, all other implementation manners that those skilled in the art can obtain without creative labor are considered to fall within the protection scope of the present invention.

[0046] The first part: Overview of the implementation solutions of the present invention

[0047] 1. System for actively maintaining the temperature of the sampling cylinder

[0048] As Figures 1-5 shown, the system includes a heat-insulated sampling cylinder 1 for deep-sea animal sampling, a gear pump 2, an alcohol dry ice cylinder 3, a plurality of temperature sensors 4, a motor compartment 5, an electronic compartment and a battery. Among them,

[0049] The heat-insulated sampling cylinder 1 includes a sampling cylinder 1-2 with a single-end closed structure and a heat-insulated cylinder 1-1 with a heat-insulated interlayer. The former is located inside the latter and is coaxially arranged, maintaining a radial distance to form an annular cavity with an annular cross-section. Optionally, the inner diameter of the heat-insulated cylinder is 20-30 mm larger than the outer diameter of the sampling cylinder (i.e., the circumferential dimension of the cavity). Water is filled in the cavity and a heat exchange coil is arranged. A coolant circulation loop is formed by connecting the gear pump 2, the heat exchange coil and the alcohol dry ice cylinder 3 through pipelines. Optionally, the heat exchange coil is a copper pipe, which is arranged in a spiral manner between the sampling cylinder and the heat-insulated cylinder and does not contact them. The pipelines in the circulation loop are rigid polyurethane pipes, and the mass ratio of alcohol to dry ice in the alcohol dry ice mixture is 2:1. The alcohol dry ice mixture is filled in the alcohol dry ice cylinder, and the temperature of the sampling cylinder is maintained stable by adjusting the water temperature in the cavity. The gear pump 2 is connected to the motor arranged in the motor compartment 5 through a transmission mechanism, and the motor is connected to the battery and the control board arranged in the electronic compartment through cables respectively. The battery can be a 48V water-sealed battery.

[0050] There are at least four temperature sensors 4, which are respectively arranged in the sampling cylinder 1-2, the isolation chamber, the alcohol dry ice cylinder 3 and the seawater. Each temperature sensor 4 is respectively connected to a data acquisition card in the electronic cabin through a cable, and the data acquisition card is electrically connected to the control board. A memory and a controller are provided on the control board, and a BP neural network module is built in the memory; the BP neural network module includes an input layer, a hidden layer and an output layer. The input layer is used to receive four key parameters: the external seawater temperature, the seawater temperature change rate, the internal temperature of the sampling cylinder, and the sampling cylinder temperature change rate. The hidden layer is used to process the input data and extract features. The output layer is used to output the gear pump speed as the calculation result; the controller is used to call the BP neural network module for calculation and send a control signal to the motor, and finally realize the active and precise maintenance of the sampling cylinder temperature.

[0051] As Figures 2-3 shown, the heat preservation cylinder 1-1 includes a front end cover 1-3, a cylinder body 1-4 and a rear end cover 1-5. The two end covers are hermetically installed on the cylinder body 1-4 through gaskets and bolts; the sampling cylinder 1-2 is fixedly installed between the two end covers of the heat preservation cylinder, and its rear end is closed and there is a sample inlet at the front end. A central through hole is provided on the front end cover 1-3 of the heat preservation barrel 1-1 and is equipped with a detachable circular heat preservation sleeve, which can be embedded in the central through hole and sealed through an annular gasket. After the sampling cylinder 1-2 completes sampling, the heat preservation sleeve is stuffed into the central through hole on the front end cover 1-3 to achieve a sealed fit.

[0052] As Figure 4 shown, the alcohol dry ice cylinder 3 includes a cylinder body 3-4, a front end cover 3-3 and a rear end cover 3-1. The front and rear end covers are hermetically installed on the cylinder body through gaskets and bolts; a pipe joint is provided on the rear end cover 3-1 or on the cylinder body close to the rear end cover 3-1, and is connected to a heat exchange coil arranged in the isolation chamber through a pipeline; two pipe joints are provided on the front end cover 3-3, which are respectively connected to the leather bag 3-5 and the input port of the gear pump 2 through pipelines; a one-way pressure relief valve 3-2 is also provided on the cylinder body 3-4.

[0053] As Figure 5 shown, the temperature sensor 4 includes a probe 4-1, a hose joint 4-2, a pipe joint nut 4-3, a silica gel hose 4-4 and a cable 4-5 arranged in sequence. The other end of the cable 4-5 is connected to the electronic cabin through a quick joint. A platinum resistor is arranged in the shell of the probe as a temperature-sensitive element, and heat-conducting silica gel is filled between the shell and the platinum electrode. In this way, the probe can be miniaturized to meet the requirements of the installation environment.

[0054] It should be noted that the present invention only relates to how to precisely maintain the temperature of the sampling cylinder, and does not involve the implementation process of the sampling function of the sampling cylinder. The structure of the sampling cylinder and the specific sampling operation process belong to the prior art, and the present invention has no improvement content on it, so it will not be described in detail.

[0055] 2. Method for Actively Maintaining the Temperature of the Sampling Cylinder

[0056] Based on the above system, the active maintenance of the temperature of the sampling cylinder can be achieved, specifically including:

[0057] (1) Build a system for actively maintaining the temperature of the sampling cylinder. Fill water in the partition cavity of the heat-insulated sampling cylinder and fill an alcohol-dry ice mixture in the circulation loop;

[0058] (2) Create a deep-water environment to determine the rate of change of the external temperature. Use a sufficient amount of known data as the training set to train the BP neural network module; these known data include the corresponding relationships between the pump speed and various temperature parameters under different temperature environments;

[0059] During the training process, the gradient descent method is used to optimize the weights and biases of the neural network; the regression function is used to calculate the output value from the hidden layer to the output layer, and the deviation is defined as the distance between the output value and the target value; error analysis is performed on the output result and the expected result, and the weights and thresholds are modified; by continuously iterating and updating the weights and biases until the deviation meets the requirements or the output result is consistent with the expected result, the training of the neural network model is completed;

[0060] (3) Fix and install the system for actively maintaining the temperature of the sampling cylinder on the frame of the deep-sea biological sampling device, and use the mother ship to carry and lower it to the sampling area; first start the motor to drive the gear pump, and use the alcohol-dry ice mixture to cool the water in the partition cavity until it is consistent with the seawater temperature in the sampling area; then use the deep-sea biological sampling device to conduct deep-sea biological sampling. After sending it into the sampling cylinder, close the inlets of the sampling cylinder and the heat-insulated barrel;

[0061] (4) During the process of recovering the deep-sea biological sampling device, use multiple temperature sensors to continuously monitor and record the temperatures in the sampling cylinder, the partition cavity, the alcohol-dry ice cylinder, and the seawater; calculate the external seawater temperature, the rate of change of seawater temperature, the internal temperature of the sampling cylinder, and the rate of change of the sampling cylinder temperature based on the temperature measurement values, and then use them as the input for the BP neural network module for calculation; send a control signal to the motor according to the output result to adjust the speed of the gear pump, so as to actively and accurately maintain the temperature of the sampling cylinder.

[0062] As Figure 6 shown, the present invention further proposes redundant temperature protection measures, specifically: set a protection threshold based on the in-situ temperature T0 of the seawater environment in the sampling area. During the recovery process of the deep-sea biological sampling device, continuously monitor the water temperature T1 in the partition cavity; if T1 rises and reaches or exceeds 115% of T0, then forcibly start the gear pump to quickly cool the water in the partition cavity; when T1 drops below 85% of T0, forcibly turn off the gear pump.

[0063] The Second Part: A Specific Implementation Case

[0064] In the system of this example, the thermal insulation sampling cylinder 1 is used to store the biological living samples after sampling and maintain the temperature stability of their living environment. The temperature sensor 4 is used to detect the temperature changes at relevant positions, and the alcohol dry ice cylinder 3 is used to store the coolant in the circulation loop to continuously and stably supply the coolant.

[0065] Both the insulation cylinder 1-1 and the sampling cylinder 1-2 are cylinders. The radial dimension of the partition cavity between the two is 20 - 30 mm. A copper tube is installed in the partition cavity in a spiral nested manner and filled with water, which is used to transfer the cold carried by the alcohol dry ice mixture inside the copper tube to the sampling cylinder 1-2 and can ensure the temperature of the latter changes smoothly.

[0066] The front end cover 3-1 and the rear end cover 3-3 of the alcohol dry ice cylinder 3 are both circular, and screw holes are evenly distributed on their edges. They form a firm sealed fit with the cylinder body 3-4 through studs to prevent the leakage of the coolant. The front end cover 3-1 is connected to the leather bag 3-5 to maintain the pressure balance inside and outside the cylinder. The one-way valve 3-2 provides an escape channel for the gas generated by the decomposition of dry ice, which can effectively prevent the internal pressure from accumulating and further enhance the stability and safety of the system.

[0067] In the temperature sensor 4, the cable 4-5 is made of brass. The connection between it and the hose 4-4 is in the form of a closed cylindrical shell, and the tail uses a conventional quick-connect fitting for connection to the electronic cabin. The platinum resistance in the probe 4-1 is a conventional PT1000 resistance, and it is fixed to the outer shell and the cable 4-5 through thermal conductive silicone. The hose 4-4 is made of PU material, which can achieve the internal and external pressure balance of the temperature sensor.

[0068] In the coolant circulation loop, the pre-loaded dry ice interacts with the excessive alcohol. The continuous decomposition of dry ice releases a large amount of cold, making the mixture stable at an extremely low temperature of -78°C. To achieve the effective transfer of cold, a gear pump 2 is used as the circulation power source to continuously pump out the coolant in the alcohol dry ice cylinder 3; after heat exchange in the copper tube, it returns to the alcohol dry ice cylinder 3 again to form an efficient circulation loop. In this circulation loop, the pipe fittings exposed to seawater use rigid polyurethane pipes, and their excellent thermal insulation performance effectively reduces the loss of cold. In the partition cavity, copper tubes with good thermal conductivity are selected to ensure that the cold can be quickly and efficiently transferred to the inside of the sampling cylinder to achieve the temperature regulation of the water body.

[0069] To accurately control the temperature, a three-layer BP neural network structure is adopted (as Figure 7As shown in the figure, the speed control of gear pump 2 is realized. The input layer of the BP neural network accepts four key parameters: the external seawater temperature, the rate of change of seawater temperature, the internal temperature of the sampling tube, and the rate of change of the temperature of the sampling tube. The number of hidden layer neurons can be selected by referring to the empirical formula in the training process. W1 and W2 are the weight matrices of the input layer and the output layer respectively. The output layer outputs the speed of the water pump. Each neuron obtains the output value by weighting all inputs and processing them through the activation function. The weight of the input data is the parameter of the neural network. Since there will be an error between the output value and the target value, it is necessary to train the neural network by creating an environment that determines the rate of change of the external temperature, and continuously optimize the weight W in this process.

[0070] In the training process of the neural network, a large amount of known data can be used to construct a training set to perform preliminary training on the neural network. These known data include the corresponding relationship between the speed of the water pump and the temperature parameters under different temperature environments. During the training process, the gradient descent method is used to optimize the weights and biases of the neural network. The output value is calculated using a regression function from the hidden layer to the output layer, and the deviation is defined as the distance between the output value and the target value. Each time, an error analysis is performed based on the obtained results and the expected results, and then the weights and thresholds are modified, so as to obtain a model in which the output results are consistent with the expected results step by step. The weights and biases are updated by continuous iteration until the deviation meets the requirements, and the preliminary training of the neural network is completed. Then the trained neural network model is applied to the real-time control of the water pump speed. By collecting the temperature parameters in real time and inputting them into the neural network model, the predicted water pump speed can be obtained. The water pump is controlled in real time according to the speed to achieve precise temperature control.

[0071] As an additional temperature protection measure, the in-situ temperature T0 of the external seawater environment is monitored and recorded by temperature sensors during seabed operations. This data is crucial for the subsequent temperature control strategy. As the lander recovery program starts, the system monitors the water temperature T1 in the compartment between the sampling outer cylinder and the insulation layer in real time. Once T1 is found to rise and reaches or exceeds the preset safety threshold of 115% of T0, the gear pump 2 is started to quickly deliver refrigerant so that more cold energy can be transferred to the interior of the sampling cylinder 1-2 to curb further temperature increases. When T1 drops below 85% of T0, the water pump is automatically shut down to stop the cold energy transfer.

[0072] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. An active system for maintaining the temperature of a sampling cylinder based on alcohol-dry ice cycle refrigeration, characterized in that, It includes a heat-insulated sampling cylinder for deep-sea animal sampling, as well as an alcohol dry-ice cylinder, a gear pump, a motor cabin, an electronic cabin, a battery, and multiple temperature sensors; among them, the heat-insulated sampling cylinder includes a sampling cylinder with a single-end closed structure and a heat-insulated cylinder with a heat-insulated interlayer. The former is located inside the latter and arranged coaxially, maintaining a radial spacing to form an annular cavity in cross-section; water is filled in the cavity and a heat exchange coil is provided. A coolant circulation loop is formed by connecting the gear pump, the heat exchange coil, and the alcohol dry-ice cylinder through pipelines. An alcohol dry-ice mixture is filled in the alcohol dry-ice cylinder, and the temperature of the sampling cylinder is maintained stable by adjusting the water temperature in the cavity; the gear pump is connected to the motor arranged in the motor cabin through a transmission mechanism, and the motor is respectively connected to the battery and the control board arranged in the electronic cabin through cables; there are at least four of the temperature sensors, which are respectively arranged in the sampling cylinder, the cavity, the alcohol dry-ice cylinder, and the seawater. Each temperature sensor is respectively connected to a data acquisition card in the electronic cabin through a cable, and the data acquisition card is electrically connected to the control board; a memory and a controller are provided on the control board, and a BP neural network module is built in the memory; the BP neural network module includes an input layer, a hidden layer, and an output layer. The input layer is used to receive four key parameters: the external seawater temperature, the seawater temperature change rate, the internal temperature of the sampling cylinder, and the sampling cylinder temperature change rate. The hidden layer is used to process the input data and extract features. The output layer is used to output the rotational speed of the gear pump as the calculation result; the controller is used to call the BP neural network module for calculation and send a control signal to the motor, ultimately achieving the active and precise maintenance of the sampling cylinder temperature.

2. The system according to claim 1, wherein the heat-insulated cylinder includes a cylinder body, a front end cover, and a rear end cover. The two end covers are hermetically installed on the cylinder body through gaskets and bolts; the sampling cylinder is fixedly installed between the two end covers of the heat-insulated cylinder, its rear end is closed, and a sampling port is provided at the front end; a central through hole is provided on the front end cover of the heat-insulated barrel and is equipped with a detachable circular heat-insulating sleeve, and the heat-insulating sleeve can be embedded into the central through hole and sealed through an annular gasket.

3. The system according to claim 1, wherein The inner diameter of the heat-insulated cylinder is 20 - 30 mm larger than the outer diameter of the sampling cylinder.

4. The system according to claim 1, characterized in that, the alcohol dry-ice cylinder includes a cylinder body, a front end cover, and a rear end cover. The front and rear end covers are hermetically installed on the cylinder body through gaskets and bolts; a pipe joint is provided on the rear end cover or the cylinder body near the rear end cover, and is connected to the heat exchange coil through a pipeline; two pipe joints are provided on the front end cover, which are respectively connected to the leather bag and the input port of the gear pump through pipelines; a one-way pressure relief valve is also provided on the cylinder body.

5. The system according to claim 1, wherein The pipeline in the coolant circulation loop is a rigid polyurethane pipe; the heat exchange coil is a copper pipe, which is arranged in a spiral manner between the sampling cylinder and the heat-insulated cylinder and does not contact with both of them.

6. The system according to claim 1, wherein In the alcohol dry-ice mixture, the mass ratio of alcohol to dry ice is 2:

1.

7. The system according to claim 1, characterized in that, The battery is a 48V water-sealed battery.

8. The system according to claim 1, wherein The temperature sensor includes a probe, a hose joint, a pipe joint nut, a silica gel hose, and a cable arranged in sequence. The other end of the cable is connected to the electronic cabin through a quick connector; a platinum resistor is arranged in the shell of the probe as a temperature-sensitive element, and heat-conducting silica gel is filled between the shell and the platinum electrode.

9. A method for actively maintaining the temperature of a sampling cylinder by using the system according to any one of claims 1 to 8, characterized in that, It includes: (1) Build a system for actively maintaining the temperature of the sampling cylinder, fill water in the cavity of the heat-insulated sampling cylinder, and fill an alcohol dry-ice mixture in the alcohol dry-ice cylinder; (2) Create a deep - water environment for determining the external temperature change rate, and use a sufficient amount of known data as the training set to train the BP neural network module; these known data include the corresponding relationships between the pump speed and various temperature parameters under different temperature environments. During the training process, the gradient descent method is used to optimize the weights and biases of the neural network; a regression function is used to calculate the output value from the hidden layer to the output layer, and the deviation is defined as the distance between the output value and the target value. Conduct an error analysis on the output result and the expected result, and modify the weights and thresholds; continuously iterate to update the weights and biases until the deviation meets the requirements or the output result is consistent with the expected result, completing the training of the neural network model. (3) Fix the system for actively maintaining the temperature of the sampling cylinder on the frame of the deep - sea biological sampling device, and use the mother ship to carry and lower it to the sampling area; first, start the motor to drive the gear pump, and use the alcohol - dry ice mixture to cool the water in the partition chamber until it is consistent with the seawater temperature in the sampling area; then use the deep - sea biological sampling device to conduct deep - sea biological sampling. After sending the sample into the sampling cylinder, close the inlets of the sampling cylinder and the heat - preservation barrel. (4) During the process of recovering the deep - sea biological sampling device, use multiple temperature sensors to continuously monitor and record the temperatures in the sampling cylinder, the partition chamber, the alcohol - dry ice cylinder, and the seawater; calculate the external seawater temperature, the seawater temperature change rate, the internal temperature of the sampling cylinder, and the sampling cylinder temperature change rate based on the temperature measurement values, and then use them as the input for the BP neural network module for calculation; send a control signal to the motor according to the output result to adjust the speed of the gear pump, thereby achieving the active and precise maintenance of the sampling cylinder temperature.

10. The method according to claim 1, characterized in that, Set a protection threshold based on the in - situ temperature T0 of the seawater environment in the sampling area, and continuously monitor the water temperature T1 in the partition chamber during the recovery process of the deep - sea biological sampling device; if T1 rises and reaches or exceeds 115% of T0, then forcibly start the gear pump to quickly cool the water in the partition chamber; when T1 drops below 85% of T0, forcibly turn off the gear pump.

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