Three-stage oxygen supply control method and device for space aquatic closed experiment system

Abstract

The invention relates to a three-stage oxygen supply control method and device for a space aquatic closed experiment system, and belongs to the technical field of space life science. The method comprises the following steps: primary biological oxygen supply (turning on an algae chamber lamp when dissolved oxygen is less than 5 mg / L, and turning off the lamp when dissolved oxygen is more than 7 mg / L); second-stage membrane type gas exchange (a circulating pump drives a water body to be oxygenated through a waterproof breathable membrane); and three-stage emergency direct supply (an oxygen bag and an air pump directly supply pure oxygen for 2 seconds). The device is composed of a sensing module (a dissolved oxygen sensor), an execution module (an LED lamp, a membrane exchange unit and an air pump) and a central control unit. Through graded oxygen supply and closed-loop control, the problem of unstable biological oxygen supply in a space environment is solved, and continuous balance of dissolved oxygen of the algae-fish symbiotic system is ensured.

Description

Technical Field

[0001] It belongs to the field of space life science technology, specifically involving a three-stage oxygen supply control method and device for a space aquatic closed experimental system. Background Technology

[0002] Conducting aquatic ecological experiments in a microgravity environment is an important way to verify and improve controlled ecological life support systems. Its core lies in maintaining the dynamic balance between the biological community and the physicochemical environment within the system. Dissolved oxygen level is one of the most critical parameters, directly related to the survival, growth, and metabolism of aquatic organisms (such as fish and algae), and affecting the material cycle and energy flow of the entire system.

[0003] Traditional life support systems rely heavily on physicochemical methods or the photosynthesis of single organisms (such as microalgae) for oxygen supply. However, the unique conditions of space environments, such as microgravity and limited resources, coupled with the finite scale of experimental systems, lead to fluctuations in biological activity and pose challenges to stability. Once the oxygen-producing organisms (such as algae) in the system become less active or enter a period of decline due to environmental stress, the system's photosynthetic oxygen production capacity will drop sharply. Self-sustaining through biological means alone will be insufficient to guarantee a continuous and stable oxygen supply, potentially leading to the collapse of the entire aquatic ecosystem and experimental failure.

[0004] Therefore, developing an intelligent dissolved oxygen regulation system that adapts to the characteristics of the space environment and possesses multiple backup and emergency response capabilities has become an urgent need to ensure the successful operation of in-orbit aquatic ecological experiments. This system not only requires real-time monitoring and precise control of dissolved oxygen, but also necessitates the design of a tiered oxygen supply strategy. When biological oxygen supply is insufficient, it must seamlessly switch to a physical backup scheme to ensure that the system's gaseous environment remains in a safe and controllable equilibrium, thereby laying the foundation for long-term, stable space life support technology research. Summary of the Invention

[0005] To address the technical problems mentioned above, this invention proposes a three-stage oxygen supply control method and device for a closed-loop space aquatic experimental system. The core objective of this invention is to design and validate a multi-stage intelligent dissolved oxygen control system applicable to closed-loop space aquatic experimental devices. This system aims to solve the problem of unstable oxygen supply caused by the special space environment and fluctuations in biological activity, ensuring the long-term stable operation of the experimental ecosystem in orbit.

[0006] The technical solution of the present invention is as follows:

[0007] A three-stage oxygen supply control method for a closed aquatic experimental system includes the following steps:

[0008] Primary oxygen supply: Dissolved oxygen levels in the fish culture room are monitored in real time by a dissolved oxygen sensor. When dissolved oxygen is below 5 mg / L, the LED lights in the algae chamber are turned on to promote photosynthetic oxygen production. When dissolved oxygen is above 7 mg / L, the light source is turned off.

[0009] Secondary oxygen supply: When dissolved oxygen remains below the primary threshold or algal activity decreases, the membrane gas exchange system is activated. The circulating pump drives the water to flow through the waterproof and breathable membrane, using the oxygen partial pressure difference of the external environment to supplement dissolved oxygen.

[0010] Three-level oxygen supply: When dissolved oxygen reaches the emergency threshold, the oxygen bag is turned on and pure oxygen is supplied directly to the fish room via the air pump for 2 seconds, and then turned off;

[0011] Once dissolved oxygen levels return to a safe range, the emergency oxygen supply mode will be gradually discontinued.

[0012] In the above technical solution, the membrane gas exchange system includes a circulation pump and a waterproof and breathable membrane. The water is oxygenated by membrane permeation and then returned to the fish room.

[0013] In the above technical solution, the intensity and light cycle of the LED lights in the algae chamber of the primary oxygen supply system can be remotely adjusted.

[0014] In the above technical solution, the three-stage oxygen supply system includes an oxygen bag, an air pump, and a one-way valve.

[0015] In the above technical solution, the safe dissolved oxygen range is 5–7 mg / L, the primary threshold is 4.5 mg / L, and the emergency threshold is 3 mg / L.

[0016] In the above technical solution, the central control unit integrates dissolved oxygen in real time and dynamically adjusts the oxygen supply strategy.

[0017] A three-stage oxygen supply device for a closed-loop space aquatic experimental system includes:

[0018] Sensing module: Dissolved oxygen sensor;

[0019] Execution modules: Algae chamber LED lights, membrane gas exchange unit including circulation pump and waterproof and breathable membrane, air pump;

[0020] Control module: Central control unit, which triggers three-level oxygen supply logic based on dissolved oxygen data.

[0021] In the above technical solution, the waterproof and breathable membrane is a biocompatible material.

[0022] In the above technical solution, the device further includes an emergency oxygen supply unit, which includes an oxygen bag and a one-way valve, and the oxygen bag has a volume of 200–500 mL.

[0023] In the above technical solution, data is transmitted via RS485 bus, and the control command response time is less than 1 second.

[0024] Beneficial effects:

[0025] 1. Achieve precise closed-loop control of dissolved oxygen levels: Through the integration of sensors and control systems, the dissolved oxygen concentration in the aquatic closed culture chamber is monitored and dynamically adjusted in real time and continuously.

[0026] 2. Establish a three-level linkage oxygen supply guarantee mechanism: Construct a graded oxygen supply system with biological oxygen supply (algal photosynthesis) as the main method, physical simulation oxygen supply (secondary, membrane gas exchange) as the auxiliary method, and emergency direct oxygen supply (tertiary, pure oxygen) as the guarantee, to ensure that the system can still maintain basic oxygen supply when any single link fails.

[0027] 3. Master and optimize gas balance control technology within the system: Through the verification and application of multi-stage oxygen supply strategies in ground and on-orbit experiments, long-term and stable autonomous control of the gas environment has been achieved for the first time in domestic space aquatic ecology research.

[0028] 4. Provide theoretical and data support for large-scale life support systems: Through the development and experimentation of this system, key process data and control experience will be accumulated, providing direct theoretical basis and technical foundation for the design and optimization of future large-scale and complex controlled ecological life support systems. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a three-stage oxygen supply control device for a closed aquatic experimental system.

[0030] Among them: 1 is an air pump, 2 is a one-way valve, 3 is an oxygen bag, 4 is a culture chamber, 5 is an LED light in the algae chamber, 6 is a circulation pump, and 7 is a waterproof and breathable membrane. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. However, the following embodiments are only for explaining the present invention, and the scope of protection of the present invention should include all the contents of the claims. Moreover, through the description of the following embodiments, those skilled in the art can fully implement all the contents of the claims of the present invention.

[0032] This invention discloses a three-stage oxygen supply control method and device for a closed aquatic experimental system, which achieves precise dissolved oxygen regulation through a three-stage oxygen supply method.

[0033] 1. The culture chamber in this invention mainly consists of a fish culture chamber (750mL) and an algae culture chamber (500mL). The two culture chambers rely on a circulating pump to drive the water flow between the two chambers, which completes the normal gas-liquid exchange between the fish chamber and the algae chamber, ensuring that the gas in the fish chamber fluctuates within a normal range during the experiment.

[0034] 2. In this invention, the dissolved oxygen sensor is placed in the fish chamber and is always in working condition to measure the dissolved oxygen value in the fish chamber in real time.

[0035] 3. During normal system operation, the system adjusts its operation based on real-time data from the dissolved oxygen sensor in the fish chamber. When dissolved oxygen levels fall below a preset threshold, the LED lights in the algae chamber are turned on to promote photosynthesis and oxygen production by algae; when dissolved oxygen levels rise above the threshold, the lights are turned off to suppress oxygen production, thus achieving a dynamic balance between oxygen production in the algae chamber and oxygen consumption in the fish chamber. This is the primary oxygen supply mode.

[0036] 4. The secondary oxygen supply system of the present invention uses "membrane gas exchange" technology to supply oxygen. The core is to use a circulating pump to drive the water in the culture box to flow through a breathable but impermeable biofilm. Since the oxygen partial pressure in the external environment is greater than the oxygen partial pressure in the water, oxygen molecules in the environment penetrate the membrane and enter the water. The oxygenated water is then returned to the fish room of the aquatic system by the circulating pump, thus replenishing the dissolved oxygen of the system.

[0037] 5. The three-stage oxygen supply system of the present invention adopts the oxygen bag supply mode. The pure oxygen stored in the external air bag is directly supplied to the fish room through the coordinated regulation of supporting components such as air pumps and valves. After the air is replenished, the pressure of the aquatic system increases for a short period of time. After the fish consume the oxygen, the carbon dioxide generated dissolves in the water, and the pressure returns to normal.

[0038] 6. The dissolved oxygen control system in this invention is a fully automatic control system. During the entire regulation process, the circulation pump runs continuously to promote water circulation in the algae chamber and the fish chamber, creating favorable conditions for gas exchange between the two chambers and further improving the uniformity and efficiency of dissolved oxygen regulation.

[0039] Example

[0040] This embodiment discloses a three-stage oxygen supply control method and device for a closed-loop aquatic experimental system. The implementation of this method and device is based on a closed-loop control logic of monitoring-judgment-execution. Through hardware integration and software algorithm collaboration, the automatic and orderly execution of the three-stage oxygen supply strategy is achieved. Figure 1 As shown, it includes: a sensing module: a dissolved oxygen sensor; an execution module: a culture chamber 4, an algae chamber LED light 5, a membrane gas exchange unit including a circulation pump 6 and a waterproof and breathable membrane 7; a control module: a central control unit that triggers a three-stage oxygen supply logic based on dissolved oxygen data; and an emergency oxygen supply unit: an air pump 1, an oxygen bag 3, and a one-way valve 2. Its implementation architecture mainly consists of three parts: the sensing and monitoring module, the central control unit, and the three-stage oxygen supply execution mechanism. The specific structure and working principle are described below:

[0041] 1. Sensing and monitoring module

[0042] This module is responsible for real-time acquisition of key system status parameters, forming the basis for control decisions. Core sensors include:

[0043] Dissolved oxygen sensor: It monitors the dissolved oxygen concentration in the water of the aquatic culture room in real time and continuously, and is the most important control input signal of the system.

[0044] After signal conditioning, the sensor data is uploaded to the central control unit. Data interaction is conducted with the monitor (PC) via an RS485 bus (using the Modbus RTU protocol). The monitoring personnel can not only send control commands in real time, but also receive parameters returned by the system in real time.

[0045] 2. Central Control Unit (Decision-Making Core)

[0046] The central control unit is equipped with intelligent control algorithms, and its main functions include:

[0047] Data fusion and status assessment: Comprehensive analysis of dissolved oxygen concentration and algal activity to determine the current stable state of the system and oxygen supply requirements.

[0048] Setpoint management and threshold judgment: preset the safe working range of dissolved oxygen (upper and lower limits) and the start / stop threshold of each level of oxygen supply system.

[0049] Execution logic control: Based on the evaluation results and preset logic, control commands are automatically generated to instruct the corresponding oxygen supply actuators to operate. Its core control logic flow is as follows:

[0050] Normal operation (Level 1 oxygen supply): When the dissolved oxygen concentration is within the set safe range and the algae activity is normal, the system relies solely on the natural oxygen supply from the photosynthesis of algae in the aquatic ecosystem, and all backup systems are in standby mode.

[0051] Secondary oxygen supply activation: When the dissolved oxygen concentration remains below the primary threshold, or algal activity significantly decreases, the central control unit determines that the primary biological oxygen supply is insufficient. It then activates the secondary oxygen supply system and issues an activation command to it.

[0052] Activating Level 3 Emergency Oxygen Supply: If the dissolved oxygen concentration continues to drop and reaches a lower emergency threshold after the Level 2 system is activated, it indicates that the Level 2 oxygen supply is insufficient to cover the shortfall. The central control unit will immediately activate the Level 3 emergency oxygen supply system to provide forced oxygen replenishment before shutting it down.

[0053] Exit: Level 3 emergency oxygen supply is shut off after a one-time oxygen replenishment and will be activated again upon re-triggered. After the oxygen replenishment operation is completed, the dissolved oxygen concentration will rise back to a safe range and stabilize for a period of time. At this point, the control system will stop Level 2 emergency oxygen supply and resume normal operation of Level 1 biological oxygen supply.

[0054] 3. Three-level oxygen supply actuator

[0055] Primary oxygen supply (biological oxygen supply): relies on oxygen-producing algae cultivated within the experimental system. When the dissolved oxygen level in the fish chamber is below 5 mg / L, the system automatically turns on the algae chamber light; when the dissolved oxygen level in the fish chamber is above 7 mg / L, the algae chamber light is turned off. At the same time, the light intensity and photoperiod can be manually adjusted to optimize its photosynthetic efficiency. This is the most preferred and sustainable oxygen supply method.

[0056] Secondary oxygen supply: "Membrane gas exchange" is adopted. The water in the culture box is driven by a circulating pump and flows through a breathable but impermeable biofilm. Since the oxygen partial pressure in the external environment is greater than the oxygen partial pressure in the water, oxygen molecules in the environment penetrate the membrane and enter the water. The oxygenated water is then returned to the aquatic system fish room by the circulating pump, increasing the overall dissolved oxygen concentration.

[0057] Three-stage oxygen supply (emergency direct supply): consists of air bags filled with pure oxygen, an air pump, and valves. Upon receiving an emergency command, the control unit opens the air pump and valves for 2 seconds, directly injecting pure oxygen into the water body to achieve rapid and high-volume oxygen replenishment to cope with the most urgent oxygen deficiency situations.

[0058] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A three-stage oxygen supply control method for a closed aquatic experimental system, characterized in that, Includes the following steps: Primary oxygen supply: Dissolved oxygen levels in the fish culture room are monitored in real time by a dissolved oxygen sensor. When dissolved oxygen is below 5 mg / L, the LED lights in the algae chamber are turned on to promote photosynthetic oxygen production. When dissolved oxygen is above 7 mg / L, the LED lights are turned off. Secondary oxygen supply: When dissolved oxygen is continuously lower than the primary threshold of 4.5 mg / L or algal activity decreases, the membrane gas exchange system is activated, and the circulating pump drives the water to flow through the waterproof and breathable membrane (7) to supplement dissolved oxygen using the oxygen partial pressure difference of the external environment; Level 3 oxygen supply: When dissolved oxygen reaches the emergency threshold, turn on the air pump (1) to supply oxygen from the oxygen bag (3) directly to the fish room for 2 seconds and then turn it off. Once dissolved oxygen levels return to a safe range, the emergency oxygen supply mode will be gradually discontinued.

2. The method according to claim 1, characterized in that: The membrane gas exchange system includes a circulation pump (6) and a waterproof and breathable membrane (7). The water is oxygenated by membrane permeation and then returned to the fish room.

3. The method according to claim 1, characterized in that: The intensity and light cycle of the LED lights in the primary oxygen supply algae chamber can be remotely adjusted.

4. The method according to claim 1, characterized in that: The three-stage oxygen supply system includes an oxygen bag (3), an air pump (1), and a one-way valve (2).

5. The method according to claim 1, characterized in that: The safe dissolved oxygen range is 5–7 mg / L, the primary threshold is 4.5 mg / L, and the emergency threshold is 3 mg / L.

6. The method according to claim 1, characterized in that: The central control unit integrates dissolved oxygen data in real time and dynamically adjusts the oxygen supply strategy.

7. A three-stage oxygen supply device for a closed-loop aquatic experimental system, characterized in that, include: Sensing module: Dissolved oxygen sensor; Execution modules: Algae chamber LED light (5), membrane gas exchange unit including circulation pump (6) and waterproof and breathable membrane (7), air pump (1); Control module: Central control unit, which triggers three-level oxygen supply logic based on dissolved oxygen data.

8. The apparatus according to claim 7, characterized in that: The waterproof and breathable membrane (7) is a biocompatible material.

9. The apparatus according to claim 7, characterized in that: The device also includes an emergency oxygen supply unit, which includes an oxygen bag (3) and a one-way valve (2), with the oxygen bag having a volume of 200–500 mL.

10. The apparatus according to claim 7, characterized in that: Data is transmitted via RS485 bus, and the control command response time is less than 1 second.

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