Supply system for an energy converter

Abstract

The present invention relates to a supply system (100) for supplying a consumer (201) with a working fluid, wherein the supply system (100) comprises an actuating cylinder (107), a compression cylinder (109), a piston (111) and a thermal element (113). The invention further relates to an energy conversion system (200) for converting energy.

Description

[0001] Description

[0002] title

[0003] Supply system for an energy converter

[0004] The presented invention relates to a supply system for supplying a consumer with an operating medium and an energy conversion system for converting energy according to the appended claims.

[0005] State of the art

[0006] In order to minimize climate change, solutions to avoid greenhouse gas emissions are currently being sought in many areas. One promising solution is to replace fossil fuels with hydrogen.

[0007] Another way to avoid greenhouse gas emissions is to use synthetic fuels, some of which can also be stored cryogenically.

[0008] On the one hand, hydrogen appears in many respects to be an almost ideal replacement, since its use eliminates not only greenhouse gas emissions but also other pollutant emissions.

[0009] On the other hand, the storage of hydrogen still poses a problem because hydrogen requires very large storage volumes due to its low density and the flammability of mixtures with air must be taken into account when using hydrogen.

[0010] One way to solve these problems is to store hydrogen as a cryogenic fluid. This can be done either at low pressures and extremely low temperatures (e.g., 4-6 bar, approx. 25 K), or at high pressures at slightly higher temperatures (e.g., 350 bar, approx. 70 K).

[0011] To prevent unwanted evaporation and the subsequent need to vent hydrogen, the storage containers or tanks used must be not only hydrogen-tight but also very well thermally insulated. However, this creates the problem that the pressure in the tank drops when hydrogen is withdrawn.

[0012] A further problem is the provision of the necessary inlet pressure of the consumer, such as a combustion engine, since, depending on the storage strategy chosen, the hydrogen is stored in the tank at a pressure below the required inlet pressure of the consumer.

[0013] To maximize the storage capacity of a given tank, it is therefore necessary to artificially increase the pressure inside or outside the tank. However, the continuous operation of pumps under cryogenic conditions remains a challenge.

[0014] Disclosure of the invention

[0015] Within the scope of the invention presented, a supply system and an energy conversion system are presented. Further features and details of the invention emerge from the respective subclaims, the description, and the drawings. Features and details described in connection with the supply system according to the invention naturally also apply in connection with the energy conversion system according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is always made to each other.

[0016] The invention presented serves, in particular, to provide a means of safely supplying a consumer, such as an energy converter, with an operating medium, such as hydrogen. Thus, according to a first aspect of the invention presented, a supply system for supplying a consumer with an operating medium is presented.

[0017] The proposed supply system comprises a working cylinder, a compressor cylinder, a piston and a thermal element, wherein the working cylinder is fluidly connected on the inlet side to the thermal element and on the outlet side to the energy converter of operating medium flowing out of the working cylinder, and wherein the compressor cylinder is fluidly connected via a first opening to a liquid tank for storing operating medium and via a second opening to the thermal element.

[0018] Furthermore, the piston is movably mounted in the working cylinder and the compressor cylinder between a bottom dead center position and a top dead center position, and forms a working surface in the working cylinder that is larger than a compression surface of the piston formed in the compressor cylinder, so that when the operating medium heated by the thermal element expands in the working cylinder, the piston moves in the compressor cylinder and the operating medium located in the supply system is compressed by a pneumatic transmission.

[0019] In this context, a pneumatic transmission is understood to mean an increase in pressure caused by different sized surfaces of a piston when the piston moves in a volume, so that the piston transfers a force provided to move the piston on its working surface to a smaller compression surface and, as a result, increases a force provided by the compression surface relative to the force provided at the working surface.

[0020] The proposed supply system is based on a single piston that moves in two fluidically separated chambers, namely a working cylinder and a compressor cylinder. Accordingly, a movement of a part of the piston located in the working cylinder causes a part of the piston located in the compressor cylinder to move along with it. Accordingly, the piston transfers mechanical energy from the working cylinder to the compressor cylinder.

[0021] To provide a force acting on the piston in the working cylinder to move it between a top dead center and a bottom dead center, the proposed supply system comprises a thermal element, such as an evaporator, which heats the operating medium flowing into the working cylinder so that the operating medium expands in the working cylinder and, as a result, moves the piston.

[0022] The movement of the piston compresses or condenses the operating medium in the compressor cylinder, so that the pressure in the line system increases when the compressed operating medium is discharged into a line system of the supply system.

[0023] The pressure in the line system is increased by the movement of the piston until it corresponds at least to the pressure of a supply line for supplying an energy converter, for example between 50 bar and 70 bar, so that the compressed operating medium flows from the supply system to the energy converter and the latter can be operated continuously.

[0024] Since the energy required to move the piston is provided by the heat supplied to the operating medium in the thermal element, the supply of higher-value energy, such as for driving active motors, can be dispensed with and the energetic efficiency of a corresponding energy conversion system can be maximized.

[0025] Furthermore, the presented supply system is compact and robust due to its design.

[0026] The supply system may include an elastic element configured to move the piston from the bottom dead center position to the top dead center position. An elastic element, such as a mechanical spring, returns the piston to its top dead center position after a work cycle for compressing the operating medium without the active supply of energy or without the operation of an actuator. Accordingly, such an elastic element contributes to the energy efficiency of a corresponding energy conversion system.

[0027] It can further be provided that a first control valve is arranged in a first connecting line between the thermal element and the working cylinder and a second control valve is arranged in a second connecting line between the working cylinder and a connection to the consumer, wherein the first control valve and the second control valve are each switchable between a through position and a closed position, and wherein the first control valve is in its through position when the second control valve is in its closed position, and the first control valve is in its closed position when the second control valve is in its through position.

[0028] A first control valve in a first connecting line between the thermal element and the working cylinder and / or a second control valve in a second connecting line between the working cylinder and a connection to the energy converter can adjust the flow of operating medium through the supply system. For example, by shutting off the second control valve until the pressure in the supply system is greater than or equal to a predetermined target pressure, the piston can be moved several times to increase the pressure in the supply system.

[0029] Furthermore, the movement of the piston can be controlled by a first control valve in a first connecting line between the thermal element and the working cylinder and / or a second control valve in a second connecting line between the working cylinder and a connection to the energy converter by alternately actuating both control valves, analogous to an inlet and outlet valve in an electrically driven piston compressor or the camshaft control of a reciprocating piston engine.

[0030] In particular, the second control valve can prevent a backflow of operating medium from a pipe system of an energy converter to be supplied into the supply system.

[0031] Furthermore, it can be provided that the proposed supply system is designed without a separate outlet valve and a pressure reducer takes over the function of the outlet valve.

[0032] It can further be provided that a pressure relief opening is formed on the working cylinder and the compressor cylinder, which is designed to discharge fluid from the supply system.

[0033] In order to prevent an overpressure, i.e. a pressure greater than a predetermined maximum pressure, a pressure relief opening can be provided which is fluidically coupled to an environment, for example by means of a pressure valve, i.e. a valve which opens from a predetermined set pressure.

[0034] Furthermore, any leakage occurring on the piston can be discharged by means of a pressure relief opening.

[0035] It can further be provided that the working cylinder comprises a first inlet opening and a second inlet opening on the inlet side and a first outlet opening and a second outlet opening on the outlet side, and a first control valve is arranged in a first connecting line between the thermal element and the working cylinder and a second control valve is arranged in a second connecting line between the working cylinder and a connecting line to the energy converter, wherein the first control valve is a 3-way valve which is switchably coupled to the thermal element via the first connecting line, to a first inlet opening of the working cylinder via a first inlet line and to a second inlet opening of the working cylinder via a second inlet line,wherein the first inlet opening opens into the working cylinder above the top dead center of the piston within the working cylinder, and the second inlet opening opens into the working cylinder below the bottom dead center of the piston within the working cylinder. The second control valve is a 3-way valve that is switchably coupled to the energy converter via a connecting line, to a first outlet opening of the working cylinder via a first outlet line, and to a second outlet opening of the working cylinder via a second outlet line. The first outlet opening opens into the working cylinder above the top dead center of the piston within the working cylinder, and the second outlet opening opens into the working cylinder below the bottom dead center of the piston within the working cylinder. The first control valve and the second control valve are configured to switch synchronously and in opposite directions.such that the connecting line can only be connected to the first inlet opening when the outlet line is connected to the second outlet opening and the connecting line can only be connected to the second inlet opening when the outlet line is connected to the first outlet opening.

[0036] Furthermore, it can be provided that the compressor cylinder comprises a first inlet opening and a second inlet opening, wherein the first inlet opening leads into the compressor cylinder in the direction of movement of the piston to its top dead center above the second inlet opening, and wherein the compressor cylinder comprises a first outlet opening and a second outlet opening, wherein the first outlet opening leads out of the compressor cylinder in the direction of movement of the piston to its top dead center above the second outlet opening.

[0037] Through multiple inlet openings and multiple outlet openings in the working cylinder or the compressor cylinder, the piston can perform compression work both when moving downwards, i.e., from a top dead center to a bottom dead center, and when moving upwards, i.e., from its bottom dead center to a top dead center. Furthermore, an elastic element for moving the piston back to its top dead center position can be dispensed with. It can further be provided that the second control valve comprises an electronic valve control configured to control the second control valve as a function of a pressure present in the connecting line in order to adjust a pressure in the connecting line.

[0038] An electronic valve control can, for example, be implemented in a processing unit and process values ​​determined by a pressure sensor or values ​​of a pressure in the connecting line determined using a mathematical model. Accordingly, the electronic valve control can, for example, open the second control valve when the pressure in the connecting line is greater than or equal to the pressure in a line system of an energy converter supplied by the supply system, thus preventing backflow of operating medium from the energy converter's line system into the supply system.

[0039] It can further be provided that the thermal element is thermally coupled to the energy converter, which is thermally coupled to the supply system in order to heat the operating medium flowing through the supply system by heat emitted by the energy converter.

[0040] In general, the thermal element can be thermally coupled to any technically feasible heat source or can include a heat source. Thermal coupling with an energy converter to be supplied, utilizing waste heat from the energy converter and correspondingly cooling the energy converter, has proven particularly advantageous from an energy perspective, as this also reduces the energy required to cool the energy converter.

[0041] It may further be provided that the supply system comprises a number of tanks configured to store operating medium under cryogenic conditions.

[0042] The tanks can be, in particular, liquid tanks for storing liquid operating media, especially hydrogen, with typical operating pressures, for example, between 4 bar and 6 bar and between 20 Kelvin and 30 Kelvin. Alternatively, the tanks can be pressure tanks for storing operating media, for example, between 300 bar and 400 bar and between 70 Kelvin and 80 Kelvin.

[0043] When using the proposed supply system with a liquid operating medium, it has proven particularly advantageous that the piston acts directly on the liquid operating medium to compress it. This results in a particularly rapid pressure increase in the supply system. Furthermore, the compression of the liquid medium results in particularly high compressor efficiency.

[0044] According to a second aspect, the presented invention relates to an energy conversion system for converting energy.

[0045] The presented energy conversion system includes an energy converter and a possible design of the presented supply system.

[0046] It can be provided that the energy converter is a fuel cell system or an internal combustion engine, in particular a hydrogen engine, ie an internal combustion engine operated with hydrogen as fuel, such as a reciprocating piston engine or a rotary piston engine.

[0047] Advantages that are described in detail for the supply system for supplying a consumer with operating medium according to the first aspect of the invention apply equally to the energy conversion system for converting energy according to the second aspect of the invention.

[0048] Further advantages, features, and details of the invention will become apparent from the following description, which describes embodiments of the invention in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination. Drawing

[0049] They show:

[0050] Figure 1 shows a schematic representation of a possible design of the presented energy conversion system with a possible design of the presented supply system,

[0051] Figure 2 shows the supply system according to Figure 1 with a further possible design of the presented supply system,

[0052] Figure 3 shows the supply system according to Figure 2 with an electronic valve control.

[0053] Description of the embodiments

[0054] Figure 1 shows an energy conversion system 200 with an energy converter 201 and a supply system 100.

[0055] The supply system 100 is connected via a tank line 101 to a tank 103 for storing operating medium and via a supply line 105 to the energy converter 201, shown here as an example in the form of a reciprocating piston internal combustion engine.

[0056] The supply system 100 comprises a working cylinder 107, a compressor cylinder 109, a piston 111 and a thermal element 113.

[0057] The working cylinder 107 is fluidly connected to the thermal element 113 on the inlet side and to the energy converter 201 on the outlet side.

[0058] The compressor cylinder 109 is fluidly connected to the tank 103 on the inlet side and to the thermal element 113 on the outlet side. Check valves 115 and 117 prevent backflow from the compressor cylinder 109 into the tank 103 or from the thermal element 113 into the compressor cylinder 109.

[0059] The piston 111 is movably mounted in the working cylinder 107 and the compressor cylinder 109 between a bottom dead center position and a top dead center position, as shown in Figure 1.

[0060] The piston 111 forms a working surface 119 in the working cylinder 107 that is larger than a compression surface 121 formed by the piston 111 in the compressor cylinder 109. Accordingly, an expansion of the operating medium heated by the thermal element in the working cylinder 107 causes the piston 111 in the compressor cylinder 109 to move from the top dead center position shown in Figure 1 to the bottom dead center position, as indicated by arrow 123.

[0061] To return the piston 111 to the top dead center position, the piston 111 is connected to an elastic element 125, shown here as an example in the form of a mechanical spring.

[0062] By the movement of the piston 111, the operating medium located in the compressor cylinder 109 is compressed and transported to the energy converter 201 through a supply line 127, which optionally runs through the working cylinder 107.

[0063] A first control valve 129 is provided to control the inflow of operating medium into the working cylinder 107. A second control valve 131 is provided to prevent the backflow of operating medium from the energy converter 201 into the supply system 100. The first control valve 129 and the second control valve 131 are switchable valves, in particular proportional valves. In principle, the control valve 131 could also be designed as a simple check valve. Alternatively, it would also be possible to use the pressure regulator 135 to prevent backflow. A pressure relief line 133 can be used to discharge any leakage along the longitudinal sides of the two pistons.

[0064] Alternatively, it is possible to integrate a protective device against overpressure in the areas between control valves 115 and 129, as well as between control valves 129 and 131. The reason for this is that the shut-off valve 117 and the control valve 129 create a closed space from which a pressure increase cannot be dissipated. The same applies analogously to the space between control valve 129 and control valve 131. Accordingly, overpressure protection can be achieved by pressure relief valves (not shown) in both areas.

[0065] Alternatively, it is also possible to design the control valve 129 as a normally open valve. In this case, when the system is shut down, both closed sections would be connected to each other, so that a single pressure relief valve would be sufficient for protection.

[0066] Alternatively, it is also possible to design the control valve 129 so that, on the one hand, it has the "normally closed" operating mode, and, on the other hand, it allows reverse flow through it due to a sufficiently high pressure gradient. However, the pressure threshold for "reverse opening" must then be selected so high that reverse flow does not occur during regular operation.

[0067] Furthermore, a pressure reducer 135 is provided in the supply line 105 to the energy converter 201, which prevents the energy converter 201 from being subjected to excess pressure.

[0068] In Figure 2, the working cylinder 107 is connected on the inlet side via a first inlet line 134 and a second inlet line 137 as well as the first control valve 129 to the thermal element 113 and on the outlet side via a first outlet line 139 and a second outlet line 141 as well as the second control valve 131 to the energy converter 201.

[0069] The first control valve 129 and the second control valve 131 are configured to switch synchronously and in opposite directions, so that a flow is enabled either according to arrows 143 and 145 or according to arrows 147 and 149, in order to supply the piston 111 with operating medium heated by the thermal element 113 both during a movement from its bottom dead center to its top dead center and during a movement from its top dead center to its bottom dead center.

[0070] Accordingly, the piston 111 performs pneumatic work in both directions of movement to compress the operating medium located in the compressor cylinder 109. In other words, the first control valve 129 and the second control valve 131 can be switched for one working stroke of the working cylinder 107.

[0071] In Figure 3, the pressure reducer 135 of the supply system 100 according to Figure 2 has been replaced by an electronic valve control 151 and a pressure sensor 153, which measures the supply pressure at the inlet of the energy converter. The valve control 151 serves to compare the actual pressure measured by the pressure sensor 153 with a setpoint value and then to control the timing of the two control valves 129 and 131 so that the energy converter 201 is supplied with the desired setpoint pressure.

[0072] At the same time, the valve control 151 serves to prevent the energy converter 201 from being supplied with excess pressure by closing the second control valve 131 when a permissible upper pressure limit is exceeded.

Claims

Claims 1. Supply system (100) for supplying a consumer (201) with an operating medium, wherein the supply system (100) comprises: a working cylinder (107), a compressor cylinder (109), a piston (111), a thermal element (113), wherein the working cylinder (107) is fluidly connectable to the thermal element (113) on the inlet side and to the energy converter (201) on the outlet side, wherein the compressor cylinder (109) is fluidly connected to a tank (103) for storing operating medium via a first opening and to the thermal element (113) via a second opening, wherein the piston (111) is movably mounted in the working cylinder (107) and the compressor cylinder (109) between a bottom dead center position and a top dead center position, wherein the piston (111) in the working cylinder (107) has a working surface (119) which is larger than a compressor surface (121) of the piston (111) formed in the compressor cylinder (109),so that when the operating medium heated by the thermal element (113) expands into the working cylinder (107), the piston (111) moves and compresses the operating medium in the supply system (100) by means of a pneumatic transmission.

2. Supply system (100) according to claim 1, characterized in that the supply system (100) comprises an elastic element (125) which is configured to move the piston (111) from the bottom dead center position to the top dead center position.

3. Supply system (100) according to claim 1 or 2, characterized in that a first control valve (129) is arranged in a first connecting line (127) between the thermal element (113) and the working cylinder (107), and a second control valve (131) is arranged in a second connecting line between the working cylinder (107) and a connection to the energy converter (201), wherein the first control valve (129) and the second control valve (131) are each switchable between a through position and a closed position, and wherein the first control valve (129) is in its through position when the second control valve (131) is in its closed position, and the first control valve (129) is in its closed position when the second control valve (131) is in its through position 4. Supply system (100) according to one of the preceding claims, characterized in that a pressure relief opening is formed on the working cylinder (107) and the compressor cylinder (109), which is designed to discharge fluid from the supply system (100).

5. Supply system (100) according to claim 1 or 2, characterized in that the working cylinder (107) comprises on the inlet side a first inlet opening and a second inlet opening and on the outlet side a first outlet opening and a second outlet opening, and in a first connecting line (127) between the thermal element (113) and the working cylinder (107) a first control valve (129) and in a second connecting line between the working cylinder (107) and a connecting line to the energy converter (201), a second control valve (131) is arranged, wherein the first control valve (129) is a 3-way valve which is connected via the first connecting line (105) to the thermal element (113), via a first inlet line (135) is switchably coupled to a first inlet opening of the working cylinder (107) and via a second inlet line (137) to a second inlet opening of the working cylinder (107), wherein the first inlet opening opens into the working cylinder (107) above the top dead center of the piston (111) within the working cylinder and the second inlet opening opens into the working cylinder (107) below the bottom dead center of the piston (111) within the working cylinder, wherein the second control valve (131) is a 3-way valve which is switchably coupled to the energy converter (201) via a connecting line, to a first outlet opening of the working cylinder (107) via a first outlet line (139), and to a second outlet opening of the working cylinder (107) via a second outlet line (141),wherein the first outlet opening opens into the working cylinder (107) above the top dead center of the piston (111) within the working cylinder, and the second outlet opening opens into the working cylinder (107) below the bottom dead center of the piston (111) within the working cylinder, wherein the first control valve (129) and the second control valve (131) are configured to switch synchronously and in opposite directions, so that the connecting line can only be connected to the first inlet opening when the outlet line is connected to the second outlet opening, and the connecting line can only be connected to the second inlet opening when the outlet line is connected to the first outlet opening.

6. Supply system (100) according to claim 5, characterized in that the compressor cylinder (109) comprises a first inlet opening and a second inlet opening, wherein the first inlet opening opens into the compressor cylinder (109) above the top dead center in the direction of movement of the piston (111) and the second inlet opening opens into the compressor cylinder (109) below the bottom dead center in the direction of movement of the piston (111), and wherein the compressor cylinder (109) comprises a first outlet opening and a second outlet opening, wherein the first outlet opening opens above the top dead center in the direction of movement of the piston (111) and the second outlet opening below the bottom dead center within the compressor cylinder (109) into the compressor cylinder (109).

7. Supply system (100) according to claim 5 or 6, characterized in that the second control valve (131) comprises an electronic valve control (151) which is configured to control the second control valve (131) as a function of a pressure present in the connecting line in order to adjust a pressure in the connecting line.

8. Supply system (100) according to one of the preceding claims, characterized in that the thermal element (113) is thermally coupled to the energy converter (201), which is thermally coupled to the supply system (100) in order to heat operating medium flowing through the supply system (100) by heat emitted by the energy converter (201).

9. Supply system (100) according to one of the preceding claims, characterized in that the supply system (100) comprises a number of tanks (103) configured to store operating medium under cryogenic conditions.

10. Energy conversion system (200) for converting energy, the energy conversion system (200) comprising: an energy converter (201), a supply system (100) according to one of claims 1 to 9.

11. Energy conversion system (200) according to claim 10, characterized in that the energy converter (201) is a fuel cell system or an internal combustion engine.

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