RU206225U1 - COMPACT CHEMICAL HYDROGEN POWER SUPPLY AND FUEL CELL BATTERY FOR MOBILE ROBOTIC SYSTEMS - Google Patents

Abstract

The utility model is intended for mobile robotic systems. The technical result consists in reducing and smoothing pressure pulsations in the gas system of the device, eliminating the threat of ignition of the discharged excess hydrogen in exceptional critical operating modes of the power source, reducing the weight of the device, achieving maximum compactness of the device and organizing optimal heat regulation. The main components of the device are: a fuel cell battery, a chemical source of hydrogen, a microprocessor control unit, a buffer battery, a controlled electronic load unit, a cooling fan, a container with water, a micropump, a compensator for hydrogen pressure surges in the gas system of the device, pressure, current and voltage sensors. The components of the device are assembled on a chassis made of an aluminum or carbon profile and a perforated base and enclosed in a housing. On one of the end walls of the case there is a control panel and connectors for connecting consumers. The chassis design provides a compact arrangement of all components of the power supply, the strength required for a mobile device, shock and overload resistance. The walls of the case are made of lightweight sandwich panels. The design of the housing allows easy access to the device components during maintenance. This utility model allows maintaining the pressure in the gas system of the power source within 0.030-0.055 MPa, ensuring a constant level of electric power generation, eliminating the threat of ignition of excess hydrogen discharged in exceptional cases. Ensuring a stable and uniform flow of hydrogen while maintaining a low operating pressure in the gas system of the power source is realized through the use of a pressure surge compensator with an inflated inner diaphragm and an optimized control system. The low operating pressure in the gas system of the power supply can significantly reduce the weight of the device due to the use of light thin-walled cartridges in the chemical hydrogen source and thin-walled light vessels for water and a pressure surge stabilizer. The two-level layout of the main components allows for efficient thermal management. 4 c.p. f-ly, 7 ill.

Description

Technical field to which the utility model belongs

The utility model relates to the field of hydrogen energy, namely to autonomous power sources based on fuel cell batteries operating on hydrogen obtained as a result of a chemical reaction of a metal hydride with water.

State of the art

US 2005/0238573 A1 describes a method for producing hydrogen by hydrolysis of metal borohydride compounds by a catalytic method. To increase the specific yield of hydrogen, an acid is used as an additive to the reaction mixture. This method is difficult to implement due to the complexity of organizing the mixing of the reacting components and the risk of formation of acid vapors in the reaction zone, which, if they enter other parts of the energy system, lead to system failure. In addition, toxic reaction products pose a particular danger.

A known method of producing hydrogen by hydrolysis of lithium aluminum hydride LiAlH4 at a temperature of 100 ° C, described in US patent 5702491 A. The disadvantages of this method include the high cost of lithium aluminum hydride due to the complexity of its production and the danger due to the formation of lithium hydroxide LiOH which is toxic.

US Pat. No. 5,514,353 describes a method for producing hydrogen by hydrolysis of lithium hydride LiH. The disadvantage of this method is the difficulty of controlling the chemical reaction due to the high chemical activity of lithium hydride.

The model of a chemical hydrogen source and a power source based on it, taken as the closest analogue, is described in US patent 10322932 B2. The model includes a chemical hydrogen source, a pressure reducing valve and a fuel cell stack. The chemical hydrogen source consists of a reaction chamber, a water tank, a micropump, an emergency pressure relief valve, a pressure sensor, a heater, and a controller. The algorithm of operation of a chemical source of hydrogen is as follows: the water is supplied to the reaction chamber under the control of a microcontroller; the water reacts with the powder of the metal hydride (magnesium hydride) to produce hydrogen. The hydrolysis process is accompanied by the release of a large amount of heat; therefore, the reaction chamber is placed in vacuum thermal insulation. At low temperatures, the thermal conductivity of such insulation is low, and at temperatures close to 300 ° C and higher, it is high due to radiation. For the initial start of the reaction, a heater is used which converts the water supplied to the reaction chamber into steam. The controller controls the water supply to the reactor so as to maintain a predetermined hydrogen pressure at the outlet of the reaction chamber in accordance with the load level on the fuel cell stack. In the design of a chemical hydrogen source, the design of the reaction chamber and the requirements for the magnesium hydride powder are of fundamental importance. The authors of the model consider two options for organizing the reaction chamber: with axial steam injection and axial initial heating, and with end steam injection and initial chemical heating when starting the hydrolysis reaction. Magnesium hydride powder with an average particle size of 5 μm was used. To prevent the removal of powder particles with a stream of hydrogen and clogging of the steam supply pipes in the reaction chamber, carbon fiber filters are used.

It can be noted that the axial arrangement of the steam inlet forms an elongated reaction zone with a large surface area and volume. When starting the reaction with a constant flow of water supply, the reaction zone will be overheated, due to its location in the middle of the powder bed, which has poor thermal conductivity. As the reaction zone moves to the periphery of the reaction chamber, this configuration will lead to excessive cooling of the reaction zone due to a multiple decrease in the density of energy release per unit volume. Consequently, the stable course of the reaction at low temperatures will cease.

Thus, in a power source based on a chemical hydrogen generator and fuel cells, considered as the closest analogue, several disadvantages can be distinguished, explained by the fact that the proposed design of the reaction chamber does not allow for the controllability of the chemical hydrogen source and the uniformity of its operation.

First, poor controllability of hydrogen generation implies a wide variation in hydrogen pressures in the gas system, which, in part, can be compensated for by the high strength of all structural elements: the reaction chamber, the water tank and the gas system connections of the hydrogen generator. The requirement for high strength, as a result, leads to a significant increase in the weight characteristics of individual components and a decrease in the specific indicators of the ratio of the energy reserve to the mass of the device, which means that it complicates the use of the proposed hydrogen generator for mobile applications.

Secondly, the system does not provide for devices that allow smoothing pressure surges in the gas system, which inevitably arise when the electrical load in the consumption circuit changes due to the mismatch in the levels of hydrogen flow generation in the chemical source of hydrogen and the consumption of hydrogen by the fuel cell stack.

In addition, the authors of the patent did not provide for a device that allows to neutralize the hydrogen discharged into the environment when critical levels of hydrogen pressure in the gas system of the power source are reached, which creates a potential threat of ignition and explosion of hydrogen when operating the device in closed, bounded spaces.

It is worth paying attention to the fact that the patent, considered as the closest analogue, does not say anything about the mutual arrangement of the main nodes of the power source and the organization of optimal heat regulation.

The tasks to be solved by the claimed utility model are to reduce and smooth out pressure pulsations in the gas system of the device, eliminate the threat of ignition of discharged excess hydrogen in exceptional critical operating modes of the power source, reduce the weight of the device, achieve maximum compactness of the device and organize optimal heat regulation.

The technical result provided by the claimed utility model consists in: firstly, in reducing the pressure level in the gas system of the device and, as a consequence, in reducing the requirements for the strength of the containers used, therefore, in reducing the thickness of the walls of the containers and reducing the total weight of the device; secondly, in smoothing the hydrogen pressure pulsations in the gas system of the device; thirdly, in a significant reduction in emergency discharges of hydrogen into the environment and an increase in the ratio of the total generated electrical energy to the mass of the device due to the presence of a controlled electronic load in the power source, which allows gradual bringing the chemical hydrogen source and the fuel cell battery, consuming hydrogen; fourthly, in eliminating the threat of a hydrogen explosion in critical situations due to the presence of a catalytic hydrogen afterburner in the device; fifth, in the optimal arrangement of the main components of the device, which allows achieving compactness and efficient organization of heat regulation of the power source. All of the above determines the possibility of using this model as an on-board power source for mobile vehicles, where low weight, compactness, reliability, and a high ratio of generated electrical energy to weight are important.

Disclosure of a utility model

To achieve this technical result, a compact power source based on a chemical hydrogen source and a battery of fuel cells (Figs. 2,3,4) is assembled on a chassis made of a carbon profile (Fig. 2, pos. 10) and a perforated base and enclosed in a housing (Fig. 2, item 1, 2) having walls made of lightweight sandwich panels, on one of which there is a connection panel (Fig. 3, item 16), on which the switching keys are located (Fig. 2, item 7, 8, 9), information display (Fig. 2, pos. 3) and connectors for connecting power consumers (Fig. 2, pos. 4,5,6). All units of the melon device have a single structural connection, provided by the chassis elements, profiles and sandwich panels of the body using screw, bolted, riveted elements, soldering and welding. The design of the device has the necessary strength, but also resistance to impacts, accelerations and overloads. Functionally, all the main components of the compact power source are connected into a single gas and electrical system (Fig. 1), the working function of which is to ensure the generation of hydrogen at the required nominal rate and the conversion of hydrogen into electric current to provide power to the payload. The algorithm of operation of the microprocessor control system is disclosed in the authors' patent RU 2707357C1 "Method and system for controlling a chemical source of hydrogen" and consists in sending signals from the control unit to the micropump, cooling fan, relay and electronic keys of electronic load based on parameters read from thermocouples and pressure sensors gas, voltage and current. Thus, an inversely proportional control of the water supply to the cartridge is realized depending on the parameter characterizing the hydrogen flow, as well as the control and maintenance of the temperature of the cartridge of the chemical hydrogen source at a predetermined level. To achieve the compactness of the arrangement of the main units, a two-tier layout was used (Fig. 3,4,5): a fuel cell bank (Fig. 3, pos. 11), a cooling fan (Fig. 3, pos. 15), a controlled load unit (Fig. 4, pos. 25), the accumulator (Fig. 4, pos. 27) - are located in the lower level; control unit (Fig. 3, pos. 17), water tank (Fig. 3, pos. 12), micropump (Fig. 4, pos. 21), pressure surge compensator (Fig. 4, pos. 20), catalytic an afterburner (Fig. 5, pos. 36), a thermostat with a cartridge (Fig. 3, pos. 13) are located in the upper level. This arrangement of the main units is due to the following reasons: ease of access and maintenance, the need to locate the center of gravity of the device in its lower part to ensure stability and optimal organization of heat regulation. A replaceable cartridge (chemical source of hydrogen) is a thin-walled tin container in the form of a cylinder with a ratio of outer diameter to outer height ranging from 0.3 to 1, installed vertically in a thermostat (Fig. 7), consisting of a body (Fig. 7 , pos. 1), having a layer of thermal insulation based on airgel (Fig. 7, pos. 2), three thermocouples (Fig. 7, pos. 7) and a fan (Fig. 7, pos. 4), controlled from the controller by signals from thermocouples and cover (Fig. 7, pos. 5). The design of a chemical hydrogen source is described in more detail in the authors' patent RU2708001C1 "Method for generating hydrogen and the design of a chemical hydrogen source".

A container for water, a cartridge (a chemical source of hydrogen), a pressure stabilization device, a battery of fuel cells, a catalytic hydrogen afterburner are connected in series by means of pipes and gas connections (Fig. 5, pos. 35) into a single gas system (Fig. 3,4,5 ).

Microprocessor control unit (Fig. 3, pos. 17), temperature sensors (Fig. 3, pos. 14), gas pressure (Fig. 3, pos. 18) and water (Fig. 5, pos. 34), fuel bank elements (Fig. 3, pos. 11), battery (Fig. 4, pos. 27), controlled electronic load (Fig. 4, pos. 25), outputs of the micanite heater (Fig. 4, pos. 24,32), cooling fan (Fig. 4, pos. 26), thermocouples (Fig. 3, pos. 14), micropump (Fig. 4, pos. 21), display (Fig. 2, pos. 3), connectors (Fig. 2 , pos. 4,5,6) and switches (Fig. 2, pos. 7,8,9) on the control panel (Fig. 3, pos. 17) are electrically connected. Access to the upper level units is opened when removing the cover of the device body (Fig. 2, pos. 1), if present. Some device models may not support it. In the device with the cover removed (Fig. 3, 4, 5), you can change the spent cartridge (chemical source of hydrogen), add water, check the integrity of the elastic membrane in the pressure stabilization device, check the tightness of the pipes and connections of the gas system, and access to the system elements management.

The main fuel element of the upper level of the structure is the cartridge (chemical source of hydrogen). Its heat dissipation is from 150 to 200% of the electrical useful power generated by the fuel cell stack. The cooling method is based on natural or forced convention. Hot air rising from the thermostat goes upward into the vents on the top of the case cover. In some cases, to enhance cooling, a fan is turned on (Fig. 5, item 26) located at the lower level of the structure. The fan sucks in air from the lower level and drives it into the thermostat housing (Fig. 7). The hot thermostat (Fig. 3, pos. 13) is separated from the containers with water (Fig. 3, pos. 12) and the compensator of gas pressure surges (Fig. 4, pos. 20) of the pressure stabilization device using a light duralumin partition (Fig. 5, pos. . 33).

At the lower level there are two fuel components: a fuel cell stack (Fig. 3, pos. 11) and a controlled electronic load (Fig. 4, pos. 25). The heat dissipation of a fuel cell stack (BFC) is 120-125% of its useful electrical power. On a controlled electronic load, up to 50% of the thermal power is allocated from the optimal electrical power of the power source at the moment the power source is started up, as well as at the moments of a sharp change in the power taken by the user's payload. Cooling of the BFC and the controlled electronic load is carried out by means of a forced convention by blowing with fans. Air exchange is carried out through openings in the side panels of the case and does not affect the heat regulation of the upper level units. Thus, due to the two-level arrangement of the main units of the power source, the maximum compactness of the device and the efficiency of cooling and thermoregulation are achieved.

The gas system of the power source contains a pressure surge compensator designed to smooth out the pressure pulsations of hydrogen in the system, maintaining it in the range of 0.030 - 0.055 MPa, to minimize the need to bleed hydrogen into the environment in exceptional cases of long-term trends in increasing the rate of hydrogen generation.

The pressure surge compensator (Fig. 6) contains a thin-walled polymer container (Fig. 6a, pos. 1) with a screw cap (Fig. 6a, pos. 2) with a sealed fitting (Fig. 6a, pos. 3) in the lid. The fitting ends on the outside with a threaded connection for connecting a gas fitting (Fig. 6a, pos. 4), and on the inside has a cylindrical seat with a groove (Fig. 6a, pos. 5) for a rubber sealing ring fixing an elastic inflation membrane ( Fig. 6a, pos. 6). The elastic rubber membrane is not highly permeable to hydrogen. There are two valves on the shell of the polymer vessel: a safety (outlet) valve (Fig.6a, pos. 7), which opens when the pressure inside the polymer vessel rises above 0.04 MPa (Fig.6b) and an inlet valve (Fig.6a, pos.8 ), which opens when the pressure in the polymer vessel drops below atmospheric (Fig. 6d).

For the coordinated operation of a chemical hydrogen source and a battery of fuel cells, the control algorithm selects the optimal water flow rate to obtain the nominal value of the hydrogen flow at the outlet. The hydrogen pressure in the gas system on average remains in the range of 0.030-0.055 MPa, however, spontaneous increases and decreases in the hydrogen generation rate periodically occur, and the pressure in the gas system of the portable power source changes. In this case, the pressure stabilizer effectively compensates for these pressure changes: with a sharp drop in pressure in the gas line, the elastic membrane is compressed (Fig.6d) and within several tens of seconds is able to maintain the required hydrogen flow and the required minimum pressure; with a sharp increase in pressure, the membrane increases in sizes (Fig. 6b) and contributes to a lower rate of pressure growth in the system to critical values, thus providing a certain margin of time for correcting the water supply by the micropump to the powder filling of the cartridge. The method of operation of the pressure surge compensator is described in more detail in the authors' patent RU2733200C1 "Compact system for stabilizing hydrogen pressure in a portable power source based on a chemical reactor".

Brief description of figures:

FIG. 1 shows a diagram of a compact power supply based on a chemical hydrogen source, reflecting all the main components of the device and their functional relationship.

FIG. 2 shows the appearance of the compact power supply from the side of the connection panel. The numbers indicate:

1. Cover

2. Foundation

3. Information display

4.USB-connector (voltage 5V, current up to 2A)

5. Connector (voltage 12V, current up to 5A)

6. Connector (voltage 12V, current up to 5A)

7. Power supply key

8. Key to start / stop reaction

9. Key for turning on the battery of fuel cells.

FIG. 3 shows a view of the compact power supply from the side of the connection panel without cover and base. The numbers indicate:

10. Chassis

11. Fuel cell battery

12. Capacity with water

13. Thermostat with fuel cartridge

14. Fuel cartridge temperature sensors

15. Box with a cooling fan of the fuel cartridge

16. Connection panel.

FIG. 4 shows the compact power supply viewed from the thermostat side without cover and base. The numbers indicate:

17.Microprocessor control unit

18. Gas pressure sensor

19. Cooling fan control board

20. Compensator for gas pressure surges

21. Micro pump

22. Pipeline for water supply to the cartridge

23. Thermostat cover

24. Power outputs of the micanite heater

25. Controlled load block

26. Cooling fan

27. Battery

28. Power detection board

29. Voltage converter

30. Valve for emergency relief of gas pressure

31. Fuel cell stack controller

32. Output of the temperature sensor of the micanite heater.

FIG. 5 shows the compact power supply from the side of the connection panel without cover and base. The numbers indicate:

33. Dural baffle

34. Water pressure sensor

35. Gas outlet pipeline

36. Afterburner.

FIG. 6 (a, b, c, d) shows the compensator of pressure surges in the gas system of the source and the principle of its operation. The numbers in FIG. 6 (a) are marked:

1. Thin-walled polymer vessel;

2. Screw cap;

3. Sealed fitting;

4. Gas threaded fitting;

5. Cylindrical seat with a groove for a rubber ring;

6. Elastic membrane;

7. Outlet (safety) valve;

8. Inlet valve.

FIG. 6 (a): The resilient inflatable diaphragm (key 6) is compressed.

FIG. 6 (b): With increasing pressure in the gas line, the elastic membrane inside the polymer container inflates and compresses the air inside the container so that the pressure inside the container and inside the membrane is equalized.

FIG. 6 (c): When the pressure in the gas line rises to 0.04 MPa, the safety valve is triggered and the air in the tank is released. The pressure inside the membrane becomes higher than the pressure in the container, and the inflation membrane occupies almost the entire volume of the polymer container.

FIG. 6 (d): With a sharp drop in pressure in the gas line, the membrane is compressed and for several tens of seconds is able to maintain the required hydrogen flow in the gas line of the power source.

FIG. 7 shows a schematic of a thermostat providing thermal insulation and thermal control of the cartridge. Numbers marked:

1. Steel cylinder

2. Thermal insulation

3. Air gap

4. Cooling fan

5. Thermal insulation cover

6. Openings for air exchange

7. Thermocouples.

Claims (5)

1. A compact power source with a high specific energy consumption for mobile robotic systems, which is a device that includes the following components: a fuel cell stack, a buffer battery, a controlled electronic load unit, a chemical hydrogen source, which is a replaceable cartridge with magnesium hydride powder, located in a thermostat with three thermocouples, a cooling fan, a container with water, a micropump for regulating the water supply to the cartridge, a compensator for hydrogen pressure surges in the gas system of the device, pressure, current and voltage sensors, a microprocessor control unit, characterized in that the above components have a two-level layout, assembled on a chassis made of a carbon profile and enclosed in a body with walls made of lightweight sandwich panels, one of which has a control panel and connectors for power supply. 2. A compact power supply with a high specific energy consumption according to claim 1, characterized in that all components of the device are included in coordinated gas and electrical subsystems having a two-level layout, controlled by a microprocessor control unit based on the results of thermocouple readings, pressure, current and voltage sensors, in such a way that the hydrogen pressure in the gas system is ensured within the range of 0.030-0.055 MPa and the generation of constant electric power by converting hydrogen into electric current on the fuel cell stack. 3. A compact power source with a high specific energy content according to claim 1, characterized in that the compensator for hydrogen pressure surges is a thin-walled polymer vessel containing an elastic rubber membrane that is weakly permeable to hydrogen, placed inside the thin-walled polymer vessel, and two valves located on the shell a polymer vessel: a safety outlet valve that opens when the pressure inside the polymer vessel rises above 0.04 MPa, and an inlet valve that opens when the pressure in the polymer vessel drops below atmospheric. 4. A compact power source with a high specific energy content according to claim 1, characterized in that it contains a catalytic hydrogen afterburner, which provides catalytic oxidation of hydrogen discharged through the valve in exceptional cases of pressure increase above 0.055 MPa and allows preventing the accumulation of hydrogen inside the power source housing and the resulting ignition and explosion. 5. A compact power supply with a high specific energy intensity according to claim 1, characterized in that a two-tier arrangement of the device components on the chassis is used to ensure maximum stability, compactness and optimal thermal control, in which a fuel cell, a cooling fan, a controlled electronic load unit, a rechargeable battery the battery is located in the lower level of the structure, and all other nodes are located in the upper level of the structure.

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