Fuel cell vehicle and a power module for use in the fuel cell vehicle

Abstract

A fuel cell power module (1) for a fuel cell vehicle comprises a fuel cell stack arrangement (11) including a fuel cell stack (111), a hydrogen supply system (113), an oxidant supply system (114), and a cooling system (115). A hydrogen refuelling arrangement (12) includes a refuelling connector (121). A hydrogen storage arrangement (15) operates at a pressure below 100 bar and comprises metal hydride containers (151) with metal hydride material (1511), a hydrogen input / output pipeline (1512), and a heating and cooling arrangement (1513). A buffer hydrogen pressure cylinder (152) is connected via a check valve and a remotely operable isolating valve (1534). A cooling supply system (165) is provided for the metal hydride containers. A heat management system (16) comprises a first heat exchanger (161), a second heat exchanger (162), and a flow switching arrangement (164) to selectively thermally couple the metal hydride containers to either the fuel cell cooling system or the cooling supply system.

Description

[0001] FUEL CELL VEHICLE AND A POWER MODULE FOR USE IN THE FUEL

[0002] CELL VEHICLE

[0003] BACKGROUND TO THE INVENTION

[0004] THIS invention relates to a fuel cell vehicle, and more particularly but not exclusively to a fuel cell vehicle utilizing low-pressure hydrogen storage based on the use of metal hydrides. The invention also relates to a power module suitable for use in the fuel cell vehicle.

[0005] A fuel cell vehicle (FCV) is a vehicle that uses a fuel cell to power an electric motor that drives the vehicle. Unlike conventional vehicles that rely on internal combustion engines running on gasoline or diesel, FCVs use hydrogen as their primary fuel source.

[0006] The fuel cell within the vehicle combines hydrogen from an onboard storage tank with oxygen from the air, generating electricity through an electrochemical process. This electricity then powers the vehicle's electric motor, propelling it forward. The only byproducts of this process are water vapor and heat, making fuel cell vehicles environmentally friendly and efficient. Fuel cell vehicles have gained attention as a potential solution to reduce greenhouse gas emissions and dependence on fossil fuels in the transportation sector. However, challenges such as the availability of hydrogen refuelling infrastructure and the cost of fuel cell technology still need to be addressed for widespread adoption.

[0007] Most of the fuel cell vehicles known in the art utilises compressed hydrogen at pressures ranging from 350 to 700 bar (35 MPa to 70 MPa) stored onboard in gas cylinders as compressed hydrogen (CGH2). A typical refuelling infrastructure for these vehicles, for example as disclosed in US9,458,968, provides hydrogen dispensed at a pressure ranging between 350 (35 MPa) and 1000 bar (100MPa). This, and similar prior art solutions, have several disadvantages, including indirect cost implications related to the high pressure refuelling; safety and reliability concerns associated with the high pressure of the stored hydrogen; and fire and explosion risks resulting from the increased risk of leaks at the high pressures, and the possible embrittlement of design materials.

[0008] Metal hydride (MH) technology offers an excellent alternative to conventional methods of hydrogen storage. The advantages include compactness, safety and reliability due to the lower pressure of the stored hydrogen, and the simplicity in design and operation. However, market penetration of MH technologies in their use for hydrogen storage on-board fuel cell vehicles requires in-depth material and system design developments towards: (i) aligning required pressure and available temperature ranges, (ii) accelerating the processes of hydrogen uptake and release, and (iii) reducing the costs.

[0009] A disadvantage of the use of MH for hydrogen storage on-board fuel cell vehicle relates to the slow rate of hydrogen refuelling (long refuelling time) and the slow rate of hydrogen supply to the fuel cell (fuel starvation) caused by the limitations of heat transfer between the MH and its heating and cooling arrangement. To overcome this problem, it has previously been suggested to combine the “high-temperature” and “low-temperature” MH materials where the latter is thermally coupled with the fuel cell cooling loop (US 2009 / 0155648), to use thermochemical energy storage material (US 10468 693), to make “hybrid” MH+CGH2 hydrogen storage arrangements (US 7 681 753) and similar solutions. All these solutions significantly complicate the hydrogen storage arrangement and increase its cost.

[0010] A hydrogen storage system integrated with fuel cell power pack (ZA2014 / 08640) has been proposed to overcome this disadvantage. The system includes a “distributed hybrid” (MH and CGH2 in separate containers) hydrogen storage and supply tank, a fuel cell power pack with an integrated heat exchanger, and a thermal management system which provides thermal coupling of a metal hydride part of the hydrogen storage arrangement with heat released from thermally loaded elements of the power pack, as well as gas coupling between MH and CGH2 parts of the hydrogen storage arrangement. The fuel cell vehicles built according to this solution have shown improved performances as compared to the ones containing CGH2 or MH hydrogen storage arrangements taken alone, as evidenced in M. Lototskyy et al, “ “Distributed hybrid’’ MH-CGH2 system for hydrogen storage and its supply to LT PEMFC power modules’’, J. Alloys Comp 645 (2015) S329-S333, M. Lototskyy et al, “Metal hydride hydrogen storage and supply systems for electric forklift with low-temperature proton exchange membrane fuel cell power module”, I nt. J. Hydrogen Energy 41 (2016) 13831-13842, and M. Lototskyy et al “Performance of electric forklift with low-temperature polymer exchange membrane fuel cell power module and metal hydride hydrogen storage extension tank”, J. Power Sources 316 (2016) 239-250.

[0011] However, the fuel cell power module with a “distributed hybrid” hydrogen storage arrangement described above exhibits problems when starting-up after partial emptying the tank during a previous operation. The reason for this is that there is a decrease of hydrogen pressure in the tank due to hydrogen absorption in the MH material during its cooling cycle to ambient temperature. To minimise the likelihood of this problem occurring, the MH part of the tank uses unstable metal hydride material having a hydrogen equilibrium pressure higher than 30 bar (3 MPa) at ambient temperature. However, to provide an acceptably short refuelling time, it is necessary to increase the pressure driving force during refuelling, which in turn requires a hydrogen dispensing pressure of about 185 bar (18 MPa). An excessively long refuelling time (above 15 minutes to achieve >90% of the tank’s capacity) is also caused by the limitations of the rate of heat dissipation from the MH to the environment via a radiator connected to the cooling loop of the MH part of the tank.

[0012] The above-mentioned disadvantages were partially mitigated in the integrated solution (M. Lototskyy et al. “Metal hydride hydrogen storage tank for fuel cell utility vehicles’’, Int. J. Hydrogen Energy 45 (2020) 7958- 7967) of a metal hydride hydrogen storage arrangement for use in a fuel cell utility vehicle (LIS2019 / 0334185) where hydrogen backflow to the metal hydride arrangement was prevented by the installation of a check valve in between its gas input-output line and a CGH2 buffer cylinder, and the use of a more stable MH material (characterised by sloping plateau in the pressure range of 5-15 bar (0.5 MPa - 1.5 MPa) at T=20°C and 10-20 bar (1 - 2 MPa) at T=50°C). This enabled the decrease of the refuelling pressure to 150 bar (15 MPa). However, permanent thermal coupling of the fuel cell stack cooling system and the heating I cooling system of the MH arrangement resulted in an excessively long refuelling time (more than 15 minutes), especially, when the refuelling was carried out immediately after driving the vehicle and the temperature of the fuel cell coolant remained above the ambient temperature. A further disadvantage related to unstable hydrogen fuel supply from the partially emptied MH material when its hydrogen equilibrium pressure approached the pressure of hydrogen supply to the fuel cell stack (4 bar - 0.4 MPa). Finally, the service of the hydrogen supply part in a fuel cell power module built within considered engineering solution poses safety problem associated with a possibility of uncontrolled release of hydrogen from the hydrogen storage arrangement.

[0013] An apparatus for refuelling on-board metal hydride hydrogen storage tank is also described in US 2007 / 0289882. More particularly, US 2007 / 0289882 teaches a heat management system which can be switched between a normal operating arrangement in which the metal hydride storage is heated and an arrangement in which the metal hydride storage is cooled to allow for refuelling. In the normal operating arrangement a first heat exchanger captures heat from a cooling system of fuel cell stack and releases the heat to the heating and cooling arrangement of the metal hydride storage. In the refuelling arrangement the cooling arrangement of the fuel cell is bypassed such that the metal hydride storage is cooled by a radiator which can arguably be considered to constitute a second heat exchanger as it exchanges heat between the metal hydride storage and the environment. It should be noted that US 2007 / 0289882 also does not disclose the use of a buffer hydrogen pressure cylinder.

[0014] It is accordingly an object of the invention to provide a fuel cell vehicle with a low-pressure storage configuration that will, at least partially, alleviate the above shortcomings.

[0015] It is also an object of the invention to provide a fuel cell vehicle which will be a useful alternative to existing fuel cell vehicles.

[0016] It is a further object of the invention to provide a fuel cell power module suitable for use in a fuel cell vehicle, that will, at least partially, alleviate the above shortcomings.

[0017] SUMMARY OF THE INVENTION

[0018] According to the invention there is provided a fuel cell power module, suitable for use in a fuel cell vehicle, the fuel cell power module comprising: a fuel cell stack arrangement including: a fuel cell stack; a fuel supply system for supplying fuel to the fuel cell stack; an oxidant supply system for supplying an oxidant to the fuel cell stack; and a fuel cell stack cooling system for removing heat generated by the fuel cell stack; a hydrogen refuelling arrangement which includes hydrogen refuelling connector; a hydrogen storage arrangement configured to operate at a hydrogen pressure of less than 100 bar, the hydrogen storage arrangement including: an assembly of metal hydride containers filled with a metal hydride material and equipped with a hydrogen input / output pipeline, a heating and cooling arrangement which comprise pipelines for supply and drainage of a heat transfer fluid; and a buffer hydrogen pressure cylinder connected to the hydrogen input / output pipeline of the assembly of the metal hydride containers, the hydrogen refuelling connector and the fuel supply system via a check valve arrangement and a remotely operating normally closed isolating valve; a metal hydride container cooling supply system for cooling the assembly of metal hydride containers; a heat management system including: a first heat exchanger which captures heat from the fuel cell stack cooling system of the fuel stack arrangement, and releases the heat to the heating and cooling arrangement of the assembly of metal hydride containers; a second heat exchanger which captures the heat from the heating and cooling arrangement of the assembly of metal hydride containers and releases the heat to the environment; and an arrangement for switching flows of heat transfer fluid which enables the metal hybrid containers to be selectively thermally coupled to the first heat exchanger or the cooling system.

[0019] There is provided for the heat management system to include a radiator which is integrated with the second heat exchanger, and which is equipped with a means for ambient air supply and warm air release.

[0020] The fuel cell power module may also include hydrogen refuelling arrangement including a hydrogen refuelling connector and receptacle.

[0021] The hydrogen storage arrangement may also include a gas distribution arrangement comprising: a pressure reducer having an output that is connected to a pipeline for hydrogen supply to the fuel supply system of the fuel cell stack arrangement; a check valve arrangement which prevents backflow of hydrogen from the buffer cylinder to the hydrogen input / output pipeline of the assembly of metal hydride containers and from the hydrogen storage arrangement to the hydrogen refuelling arrangement; and an isolating valve connected to an input of the pressure reducer.

[0022] There is provided for the fuel cell stack arrangement also to include: a power conditioning and control system; and a collection system for collecting water formed during the operation of the fuel cell stack. A further feature of the invention provides for the fuel cell power module to include: an air supply system for supplying air to the oxidant supply system; a water drain including a water drain connector.

[0023] In one embodiment the fuel cell power module there is provided for the metal hydride material to have a hydrogen equilibrium pressure below 15 bar at the ambient temperature and above 20 bar at the temperature of 50 °C.

[0024] The metal hydride material may be a multicomponent intermetallic alloy of ABs- or AB2-type characterised by the reversible hydrogen storage capacity above 120 normal litres H2 per 1 kg of the alloy when absorbing hydrogen at the temperature below 20°C and pressure above 20 bar and desorbing hydrogen at the temperature of 50°C and the pressure of 20 bar.

[0025] There is provided for the metal hydride container cooling supply system to provide circulation of a liquid coolant, the metal hydride container cooling supply system including a circulation pump and an extension tank.

[0026] In one embodiment, the metal hydride container cooling supply system provides flow of chilled water through the heating and cooling arrangement of the assembly of metal hydride containers.

[0027] In one embodiment, the metal hydride container cooling supply system provides flow of an air-water spray through the heating and cooling arrangement of the assembly of metal hydride containers.

[0028] There is provided for the metal hydride container cooling supply system to be configured to receive a supply of the chilled water or air-water spray via a connecting pipeline connected to the water drain connector of the fuel cell powder module, and hence from a water collection system of the fuel stack arrangement. According to a further aspect of the invention there is provided a fuel cell vehicle including the fuel cell module as described above.

[0029] BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Embodiments of the invention will now be described by way of a nonlimiting examples, with reference to the accompanying drawings in which:

[0031] Figure 1 is a schematic layout of the fuel cell vehicle with low-pressure hydrogen storage in accordance with one embodiment of the invention. The links between system components in the operation (driving) mode are shown by solid arrows, and the links between the system components in the refuelling mode are shown by dashed arrows;

[0032] Figure 2 is a schematic layout of the low-pressure hydrogen storage arrangement used in the fuel cell vehicle of Figure 1 ;

[0033] Figure 3 is a schematic layout of the heat management system used in the fuel cell vehicle of Figure 1;

[0034] Figure 4 is a schematic layout of a metal hydride container cooling supply system in accordance with one embodiment of the invention;

[0035] Figure 5 is a schematic layout of a metal hydride container cooling supply system in accordance with another embodiment of the invention. DETAILED DESCRIPTION OF INVENTION

[0036] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. It is noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the," and any singular use of any word, include plural referents unless expressly and unequivocally limited to one referent. As used herein, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.

[0037] Referring to the drawings, in which like numerals indicate like features, a non-limiting and simplified example of a fuel cell power module, suitable for use to power a fuel cell vehicle, in accordance with the invention is generally indicated by reference numeral 1.

[0038] The fuel cell vehicle, shown in Figure 1, includes a fuel cell power module (1) and vehicle on-board equipment (2).

[0039] The fuel cell power module (1) includes a fuel cell stack arrangement (11), a hydrogen refuelling arrangement (12) which includes a hydrogen refuelling connector (or receptacle) (121), an air supply system (13), a water draining system (14), which includes a water drain connector (141), a hydrogen storage arrangement (15) and a heat management system (16). The fuel cell stack arrangement (11) includes a PEM fuel cell stack (111) and its BoP components, which includes a power conditioning and control system (112), a fuel supply system (113), an oxidant supply system (114), a fuel stack cooling system (115), and a water collection system (116) for collection of water formed during the operation of the fuel cell stack.

[0040] During the operation, the fuel cell stack (111) consumes hydrogen fuel supplied by the fuel supply system (113) and an oxidant in the form of ambient air (13) supplied via the oxidant supply system (114). In so doing, the stack (111) generates electric power which, via the power conditioning and control system (112), is supplied to the vehicle power conditioning and control system (21) on-board the vehicle. Simultaneously, the stack (111) generates heat, which is removed by the fuel stack cooling system (115) and generates water collected in the water collection system (116).

[0041] Hydrogen fuel is supplied to the fuel supply system (113) from the hydrogen storage arrangement (15). Hydrogen release from the hydrogen storage arrangement (15) requires a supply of heat, which heat is transferred from the fuel stack cooling system (115) to the hydrogen storage arrangement (15) by way of a heat management system (16). The heat management system (16) facilitates heat transfer from a fuel cell stack cooling loop (1611) to a heating loop of the metal hydride containers (1612). Additional stack cooling is provided by ambient air (1631), where the heated warm air (1632) is released to the environment.

[0042] During refuelling, hydrogen is supplied from a refuelling infrastructure (not shown) via a hydrogen refuelling conduit (121) to the hydrogen storage arrangement (15). The heat generated while charging the hydrogen storage arrangement (15) with hydrogen is transferred by a flow of a heat transfer fluid (1621) to the heat management system (16) and is dissipated into the ambient air (1631-1632). Simultaneously, the water collected in the system (116) is removed via water drain connector (141). The features of the vehicle on-board equipment (2) including a system for power conditioning and control (21) and electric motors (22) are built according to prior art solutions of electric vehicles and out of scope of the invention.

[0043] One of the primary components of the fuel cell power module (1) in accordance with the invention is the hydrogen storage arrangement (15) schematically shown in Figure 2. Hydrogen is stored in an assembly of metal hydride containers (151). The assembly must include at least one metal hydride container filled with a metal hydride material (1511) and equipped with a hydrogen input / output pipeline (1512). The assembly also includes a heating and cooling arrangement (1513) for heating the metal hydride material when in a hydrogen output mode (endothermic desorption), and for cooling the metal hydride in the hydrogen input mode (exothermic absorption). In a preferred embodiment of the invention, the heating and cooling arrangement (1513) take the form of heat exchangers equipped with a means for the supply (1513a) and removal (1513b) of heat transfer fluid, for example, water-glycol mixture, water, or air-water spray. The means for the supply (1513a) and removal (1513b) of heat transfer fluid are in flow communication with the heat management system (16).

[0044] Since the increase in the size of individual metal hydride containers results in slowing down the rates of hydrogen absorption I desorption in I from the metal hydride material due to heat transfer limitations, for bigger amounts of the stored hydrogen it is preferable to use an assembly of several metal hydride containers of smaller size (151), with all their hydrogen input / output pipelines (1512), as well as the means for the supply (1513a) and removal (1513b) of the heat transfer fluid being connected in parallel.

[0045] To provide high enough pressure driving force for hydrogen absorption in the metal hydride material (1511), the material must have a low hydrogen equilibrium pressure, at least below 15 bar at near-ambient temperature (typically 15-20°C) at which the cooling during refuelling takes place. At the same time, during the operation of the fuel cell stack the material will be heated to the temperature not higher than the temperature of a coolant of the fuel cell stack (typically, 50°C). To avoid fuel starvation, the metal hydride material (1511) must also have high enough hydrogen equilibrium pressure - at least above 20 bar at the temperature of 50°C. Examples of the metal hydride materials which satisfy the above requirements are presented in Table 1. The materials which can be used within scope of the invention are, however, not limited by the list presented in Table 1.

[0046] The selected material must also have the maximum reversible hydrogen storage capacity in the operating range of the temperatures and hydrogen pressures, in order to minimise the amount of the metal hydride material in the hydrogen storage arrangement at the specified useable hydrogen storage capacity. Apart from the correspondence of the hydrogen equilibrium pressures of the hydrogen storage material to the required values specified above (that is necessary condition for the efficient use of the material within the invention), the maximum reversible hydrogen storage capacity also depends on the operating conditions (first of all, hydrogen absorption I refuelling pressure), as well as on such features of pressure-composition isotherms of the material as hysteresis and plateau slope. As can be seen from Table 1, the metal hydride materials based on multi-component AB2- and ABs-type intermetallic alloys are characterised by the reversible hydrogen storage capacity being above 120 normal litres H2 per 1 kg of the alloy when absorbing hydrogen at the temperature below 20°C and the pressure above 20 bar, and desorbing hydrogen at the temperature of 50°C and the pressure of 20 bar. Further increase of the hydrogen absorption (refuelling) pressure will result in the increase of the reversible hydrogen storage capacity and, in turn, the useable hydrogen storage capacity of the hydrogen storage arrangement. However, the refuelling pressure remains significantly lower than the pressure applied for the refuelling of the fuel cell vehicles within the prior art solutions that exceeds 350 bar for the vehicles with CGH2 hydrogen storage arrangements (US 9,458,968) and 150 bar for the vehicles utilising MH for hydrogen storage (M. Lototskyy et al. “Metal hydride hydrogen storage tank for fuel cell utility vehicles’’, I nt. J. Hydrogen Energy 45 (2020) 7958-7967). In doing so, the fuel cell vehicle according to the invention will be characterised by the pressure of the stored H2 not being higher than 100 bar, which is the maximum refuelling pressure necessary to provide the required hydrogen storage capacity of the hydrogen storage arrangement (15).

[0047] Table 1

[0048] The hydrogen input / output pipeline (1512) of the metal hydride containers is connected, via a gas distribution arrangement (153), to the hydrogen refuelling connector (121), the buffer hydrogen pressure cylinder (152) and the fuel supply system (113) for hydrogen supply of the fuel cell stack arrangement (11). The gas distribution arrangement (153) includes a pressure reducer (1531) having an outlet that is connected to the pipeline (1532) for hydrogen supply to the fuel supply system (113) of the fuel cell stack (11), an arrangement of one-way check valves (1533) which prevents flow of hydrogen from the buffer cylinder (152) to the hydrogen input / output pipeline (1512) of the assembly of metal hydride containers (151), and an isolating valve (1534) connected to the inlet of the pressure reducer (1531).

[0049] The check valve arrangement (1533) includes a first check valve in the hydrogen refuelling line (1533a), usually integrated in the refuelling connector / receptacle (121), and a second check valve (1533b), installed in between the hydrogen input / output pipeline (1512) of the metal hydride containers and the buffer cylinder (152). When the fuel cell is not operating, the temperature of the metal hydride material (1511) drops, resulting in a drop of hydrogen pressure in the metal hydride containers (151). However, due to the presence of the check valve (1533b), pressurised hydrogen does not flow from the buffer cylinder (152) to the metal hydride containers, and the quantity of pressurised hydrogen remaining in the buffer cylinder (152) is sufficient for the start-up of the fuel cell stack (111) on the next operation cycle. The heat released during further operation of the fuel cell is transferred by the heat management system (16) to the heating and cooling arrangement (1513) of the metal hydride containers (151), thus resulting in the heating of the metal hydride material (1511) and the increase of hydrogen pressure in the containers (151). When the pressure becomes higher than the pressure in the buffer cylinder (152), the check valve (1533b) opens, thus resuming hydrogen supply from the metal hydride containers (151).

[0050] The isolating valve (1534) is opened during the fuel cell operation and may be closed when hydrogen supply to the fuel cell becomes hazardous (appearance of hydrogen leaks) or not required (during refuelling or service works). The presence of the isolating valve (1534) is particularly important for the safety of the service works associated with disassembling of the fuel supply system (113) because it prevents the escape of large amounts of hydrogen from the hydrogen storage arrangement (15) into the atmosphere (via the reducer (1531), the hydrogen supply pipeline (1532) and disassembled gas connections of the fuel supply system (113)). Preferably, the isolating valve (1534) is a remotely controlled valve powered from power conditioning and control system (112) of the fuel cell stack arrangement (11).

[0051] The cooling of metal hydride material (1511) during the exothermic hydrogen absorption during refuelling and its heating during the endothermic desorption when supplying hydrogen to the fuel cell stack is provided by the heating and cooling arrangement (1513). This heating and cooling arrangement (1513) comprises pipelines for supply (1513a) and drainage (1513b) of the heat transfer fluid connected to the second heat exchanger (162) of the heat management system (16).

[0052] The heat management system (16) of the fuel cell power module (1) in accordance with one embodiment of the invention is schematically shown in Figure 3.

[0053] The heat management system (16) includes a first heat exchanger (161) connected to the fuel stack cooling system (115) of the fuel cell stack arrangement (11) via the fuel cell cooling loop (1611). The first heat exchanger (161) transfers the heat to the heating loop (1612) of the metal hydride containers (151) via their heating and cooling arrangement (1513). A high temperature heat transfer fluid flows in the heating loop (1612) from the outlet (1612a) of the heat exchanger (161), to the metal hydride containers (151) (through the supply (1.5.1.3a) conduit), and then to the second heat exchanger (162) (though the drain (1513b) conduit), where it is cooled by the radiator (163) and returned to the inlet (1612b) of the first heat exchanger (161). The heating loop (1612) also comprises a circulation pump (1612c) and an expansion tank (1612d).

[0054] The configuration described above results in heating of the metal hydride containers (151) from the fuel stack cooling system (115) of the fuel stack with accessories (11), thus supplying hydrogen fuel necessary for its operation.

[0055] Alternatively, when the fuel cell is not operating and refuelling of the hydrogen storage arrangement (15) with hydrogen takes place, the heating and cooling arrangement (1513) of the metal hydride containers (151) are switched to the connection with the metal hydride container cooling supply system (165). A chilled heat transfer fluid from the output of the metal hydride container cooling supply system (165) then flows through the supply (1513a) and drain (1513b) conduits of the heating and cooling arrangement (1513) of the metal hydride containers (151), to the second heat exchanger (162) where it is cooled by the radiator (163) and returns to the inlet of the metal hydride container cooling supply system (165). This configuration results in cooling of the metal hydride containers (151) during refuelling of the hydrogen storage arrangement (15).

[0056] Switching between the heating (fuel cell operation) and the cooling (refuelling) modes of the heat management system (16) is facilitated by an arrangement for switching flows of heat transfer fluid (164) that enables alternative thermal coupling of the heating and cooling arrangement (1513) of the assembly of metal hydride containers (151) with a heating loop (1612) of the first heat exchanger (161) and with the metal hydride container cooling supply system (165) of the assembly of metal hydride containers (151).

[0057] In the simplest embodiment of the invention, not limiting its scope, the arrangement (164) may comprise two 3-way valves. The first 3-way valve (164a) is configured selectively to supply heat transfer fluid either from the heating loop of the metal hydride containers (1612) or, alternatively, from the outlet of the metal hydride container cooling supply system (165) to the supply pipeline (1513a) of the heating and cooling arrangement (1513) of the metal hydride containers (151). The second 3-way valve (164b) drains the heat transfer fluid from the drain pipeline (1513b) of the heating and cooling arrangement (1513) of the metal hydride containers (151) and coneys it selectively to either the return (1612b) of the heating loop of the metal hydride containers (1612) or, alternatively, to the inlet of the metal hydride container cooling supply system (1.6.5).

[0058] An important feature of the invention is in the separation of the cooling loop of the fuel cell stack (1611) and the heating loop (1612) of the metal hydride containers (151), which adds flexibility in the selection of the heat transfer fluid for the latter without compromising operating reliability of the fuel cell stack. It is known that cooling systems of the closed cathode liquid- cooled fuel cell stacks (most frequently used in fuel cell vehicles due to their high power and long lifetime) require the use of high purity coolants (as a rule mixture of glycol and deionised water) to avoid potential short circuits of the electric circuits. This strict requirement is not the case for the heat transfer fluid for the heating and cooling of metal hydride containers, with the proposed configuration thus allowing for the use of less expensive and more efficient solutions of their heating and, especially, cooling.

[0059] The metal hydride container cooling supply system (165) of the assembly of metal hydride containers (151) in accordance with a first embodiment of the invention is schematically shown in Figure 4.

[0060] In this embodiment, the cooling is provided by the circulation of a liquid coolant (water or water-glycol mixture) with the help of a circulation pump (1651) and an extension tank (1652). The cooling is provided by ambient air supplied to the second heat exchanger (162), which is integrated with the radiator (163).

[0061] Although the embodiment described above is more efficient when compared to the prior art solutions due to the complete separation of the metal hydride container cooling supply system (165) from the heating loop (1612) with the help of the arrangement for switching flows of heat transfer fluid (164), its efficiency strongly depends on the temperature of the supplied ambient air (1631), and may significantly decrease during hot weather resulting in slower cooling and, in turn, longer refuelling time. It should also be noted that the metal hydride container cooling supply system (165) operates at a refuelling station, which has to have additional service facilities including removal of water (14) from the water collection system (116) for water collection via water drain connector (141). However, as can be seen in Figure 4, in the embodiment under discussion metal hydride container cooling supply system (165) itself operates independently from the refuelling station.

[0062] Another embodiment of a metal hydride container cooling supply system (165) is schematically shown in Figure 5, and in this case utilises services which may be available at the refuelling station, including a water drain (14) and a supply of a chilled water (1653), which is used as a coolant in this embodiment. The chilled water supplied from the connecting pipeline (1654) flows through the heating and cooling arrangement (1513) of the metal hydride containers (151), through the second heat exchanger (162), and into a drain pipeline (1655). From here it is subsequently drained through the water drain connector (141) after being mixed with the water from the water collection system (116) for collection of water formed during the operation of the fuel cell stack (111). A check valve arrangement (1656) in the mixing manifold eliminates water backflow.

[0063] The embodiment described above provides more efficient cooling of the metal hydride containers (1.5.1) thus assisting in the faster refuelling of the hydrogen storage arrangement (15). Operation is, however, integrated with the refuelling station.

[0064] A further increase of the cooling efficiency is achieved in a third embodiment of the invention (not shown) when the coolant supplied to the line (1653) is an air-water spray. In this embodiment, evaporation of water in the heating and cooling arrangement (1513) of the metal hydride containers (151) results in additional cooling and, in turn, in the acceleration of hydrogen absorption thus shortening refuelling time of the fuel cell vehicle.

[0065] The invention results in fuel cell vehicles, particularly, materials handling units, which are characterised by higher safety and reliability due to the lower pressures of hydrogen storage, as compared to prior art solutions. The use of hydrogen storage technology proposed by the invention will also result in a decrease of cost of ownership of the fuel cell vehicles due to a significant decrease in the hydrogen refuelling costs.

[0066] When considering US 2007 / 0289882, it should be noted that the present invention noticeably differs from the perspective of the heat management system. In US 2007 / 0289882, the primary heat transfer loop that is coupled with the cooling system of the internal combustion engine or fuel cell includes a radiator, as well as valves which allow cooling fluid either to pass through or bypass the radiator. In the present invention, the equivalent primary heat transfer loop (1611) does not include these elements, as they are now effectively part of a secondary heat transfer loop (1612). In other words, using the terminology of US 2007 / 0289882, in the present invention the radiator (the second heat exchanger 162) was moved from the primary heat transfer loop to a secondary heat transfer loop. This solution in the present invention adds flexibility in the management of the heating and cooling of metal hydride hydrogen storage vessels and simplifies the cooling system of a fuel cell stack arrangement.

[0067] Furthermore, introducing the flow switching arrangement (164) in the present invention allows for more efficient cooling of the metal hydride hydrogen storage vessels due to the possibility to use a separate cooling loop I metal hydride container cooling supply system (165) which may include a further coolant supply. This is not obvious from US 2007 / 0289882 where additional coolant (expanded compressed air with or without addition of water) can be added only to air flow blowing across the radiator. In the present invention, the additional coolant (water or air-water mix) is directly added to the metal hydride container cooling supply system (165), thus bypassing the stage of air-liquid heat exchange in the radiator and providing more efficient cooling. Another benefit of this solution in the present invention is in the faster cooling of the metal hydride containers (151) after switching the arrangement (164) from the fuel cell operation to the refuelling mode. In the arrangement of US 2007 / 0289882 after shutdown of the internal combustion engine or fuel cell (60), residual heat will still be transferred from the primary to the secondary heat transfer loop via the heat exchanger while in the present invention the flow switching arrangement (164) allows to immediately switch the heating and cooling arrangement (1513) of the metal hydride containers (151) to the flow of cold heat transfer fluid provided by the cooling supply system (165). The use of the buffer pressure cylinder is in itself known in the art, for example as disclosed in US 2009 / 0095016. Even though this solution avoids hydrogen fuel starvation during start-up of the power module, or its operation at the peak loads, its main disadvantage is in the possibility of hydrogen backflow from the hydrogen cylinder to metal hydride part of the hydrogen supply arrangement that can result in unacceptable decrease of the pressure of supplied hydrogen. In US 2009 / 0095016 this problem is mitigated by the installation of cut-off valves in the hydrogen pipelines of the buffer cylinder and metal hydride tank, respectively. However, this solution complicates the operation of the hydrogen-consuming system in US 2009 / 0095016 and results in the requirement for either manual or automatic intervention for opening / closing the valves 5 and 7 when performing different operation modes, i.e., hydrogen refuelling, or operation of the hydrogen consuming unit including its stops and re-starts.

[0068] In the present invention, the buffer hydrogen pressure cylinder (152) is connected to the hydrogen input / output pipeline (1512) of the assembly of the metal hydride containers (151), the hydrogen refuelling connector (121) and the fuel supply system (113) via a check valve arrangement (1533) and a remotely operating normally closed isolating valve (1534). This solution prevents hydrogen backflow from the buffer cylinder (152) to the assembly of the cooled metal hydride containers (151). It also enables the supply of hydrogen fuel to the fuel supply system (113) of the fuel cell stack (111) only when the latter is operating. Importantly, the features above are provided passively, i.e., it does not require additional manual or automated intervention that simplifies the control and increases the system reliability and safety. The synergistic interaction of the suggested solution of the gas communicating of the buffer cylinder (152) with other components of the hydrogen storage arrangement (15) and the heat management system (16) is in the fact that cooling of the metal hydride containers (151) by the heating and cooling arrangement (1513) results in the drop of hydrogen pressure in the hydrogen input / output pipeline (1512) thus providing a pressure drop across the check valve (1533B) and, in turn, its closing. It prevents hydrogen backflow from the buffer cylinder (152) into the metal hydride containers (151). When the latter are heated up, the pressure in the hydrogen input / output pipeline (1512) increases, which allows hydrogen to flow from the metal hydride containers (151) via the opened check valve (1533B) to the buffer (152) and, if the fuel cell stack (11) is operating, to its hydrogen fuel supply system (113), via the opened valve (1534) and the pressure reducer (1531).

[0069] The engineering solutions suggested in the invention allow for a number of possible variations and modifications depending on the type of the fuel cell vehicle, requirements to the hydrogen storage capacity of its storage tank and to the refuelling time, availability and specification of service pipelines in the hydrogen refuelling infrastructure.

[0070] It will be appreciated that the above are only some embodiments of the invention and that there may be many variations without departing from the spirit and / or the scope of the invention. It is easily understood from the present application that the particular features of the present invention, as generally described and illustrated in the figures, can be arranged and designed according to a wide variety of different configurations. In this way, the description of the present invention and the related figures are not provided to limit the scope of the invention but simply represent selected embodiments.

[0071] The skilled person will understand that the technical characteristics of a given embodiment can in fact be combined with characteristics of another embodiment, unless otherwise expressed or it is evident that these characteristics are incompatible. Also, the technical characteristics described in a given embodiment can be isolated from the other characteristics of this embodiment unless otherwise expressed. Key to reference numerals.

[0072] I Fuel cell power module:

[0073] I I Fuel cell stack arrangement:

[0074] 111 Stack

[0075] 112 Power conditioning and control

[0076] 113 Fuel supply

[0077] 114 Oxidant supply

[0078] 115 Fuel stack cooling system

[0079] 116 Water collection system

[0080] 12 Hydrogen refuelling arrangement

[0081] 121 Hydrogen refuelling connector / receptacle

[0082] 13 Air supply system

[0083] 14 Water draining system

[0084] 141 Water drain connector

[0085] 15 Hydrogen storage arrangement:

[0086] 151 Metal hydride containers:

[0087] 1511 Metal hydride material

[0088] 1512 Hydrogen input / output pipeline

[0089] 1513 Heating and cooling arrangement: a) Supply of heat transfer fluid b) Drain of heat transfer fluid

[0090] 152 Buffer cylinder

[0091] 153 Gas distribution arrangement:

[0092] 1531 Pressure reducer

[0093] 1532 Hydrogen supply to fuel cell stack

[0094] 1533 Check valve arrangement: a) Hydrogen refuelling b) Hydrogen supply from the metal hydride containers (151) to the buffer cylinder (152)

[0095] 1534 Isolating valve

[0096] 16 Heat management system:

[0097] 161 First heat exchanger

[0098] 1611 Cooling loop of fuel cell stack

[0099] 1612 Heating loop of metal hydride containers a) Output of heat transfer fluid b) Input of heat transfer fluid c) Circulation pump d) Expansion tank

[0100] 162 Second heat exchanger:

[0101] 1621 Input of heat transfer fluid a) Supply of heat transfer fluid to metal hydride containers b) Drain of heat transfer fluid from metal hydride containers

[0102] 1622 Output of heat transfer fluid

[0103] 163 Radiator

[0104] 1631 Ambient air supply

[0105] 1632 Warm air release

[0106] 164 Arrangement for switching flows of heat transfer fluid: a) 3-way valve for supply of heat transfer fluid b) 3-way valve for drain of heat transfer fluid

[0107] 165 Metal hydride cylinder cooling supply system:

[0108] 1651 Circulation pump

[0109] 1652 Expansion tank

[0110] 1653 Supply of chilled water or air-water spray

[0111] 1654 Water or air-water spray connecting pipeline

[0112] 1655 Check valve arrangement

[0113] 2 Vehicle on-board equipment:

[0114] 21 Vehicle power conditioning and control

[0115] 22 Electric motors

[0116] The invention is not limited to the embodiment / s illustrated in the drawings. Accordingly, it should be understood that where features mentioned in the appended claims are followed by reference signs, such signs are included solely for the purpose of enhancing the intelligibility of the claims and are in no way limiting on the scope of the claims.

Claims

CLAIMS:

1. A fuel cell power module (1), suitable for use in a fuel cell vehicle, the fuel cell power module (1) comprising: a fuel cell stack arrangement (11) including: a fuel cell stack (111); a fuel supply system (113) for supplying hydrogen fuel to the fuel cell stack (111); an oxidant supply system (114) for supplying an oxidant to the fuel cell stack (111); and a fuel cell stack cooling system (115) for removing heat generated by the fuel cell stack (111); a hydrogen refuelling arrangement (12) which includes a hydrogen refuelling connector; a hydrogen storage arrangement (15) configured to operate at a hydrogen pressure of less than 100 bar (10 000 kPa), the hydrogen storage arrangement including: an assembly of metal hydride containers (151) filled with a metal hydride material (1511) and equipped with a hydrogen input / output pipeline (1512), a heating and cooling arrangement (1513) which comprise pipelines for supply and drainage of a heat transfer fluid; and a buffer hydrogen pressure cylinder (152) connected to the hydrogen input / output pipeline (1512) of the assembly of the metal hydride containers (151), the hydrogen refuelling connector (121) and the fuel supply system (113) via a check valve arrangement (1533) and a remotely operating normally closed isolating valve (1534); a metal hydride container cooling supply system (165) for cooling the assembly of metal hydride containers (151); a heat management system (16) including:a first heat exchanger (161) which captures heat from the fuel cell stack cooling system (115) of the fuel stack arrangement (11), and releases the heat to the heating and cooling arrangement (1513) of the assembly of metal hydride containers (151); a second heat exchanger (162) which captures heat from the heating and cooling arrangement (1513) of the assembly of metal hydride containers (151) and releases the heat to the environment; and a flow switching arrangement (164) for switching flows of heat transfer fluid which enables the metal hydride containers (151) to be selectively thermally coupled to the first heat exchanger (161) or the metal hydride container cooling supply system (165).

2. The fuel cell power module (1) according to claim 1 , wherein the heat management system (16) includes a radiator (163) which is integrated with the second heat exchanger (162), and which is equipped with a means for ambient air supply and warm air release.

3. The fuel cell power module (1) according to any one of the preceding claims wherein the hydrogen storage arrangement (15) includes a gas distribution arrangement (153) comprising: a pressure reducer (1531) having an output that is connected to a pipeline for hydrogen supply to the fuel supply system of the fuel cell stack arrangement (11); the check valve arrangement (1533) which prevents backflow of hydrogen from the buffer cylinder (152) to the hydrogen input / output pipeline (1512) of the assembly of metal hydride containers (151) and from the hydrogen storage arrangement (15) to the hydrogen refuelling arrangement (12); and the isolating valve (1534) connected to an input of the pressure reducer (1531).

4. The fuel cell power module (1) according to any one of the preceding claims wherein the fuel cell stack arrangement (11) includes: a power conditioning and control system (112); and a water collection system (116) for collecting water formed during the operation of the fuel cell stack (111).

5. The fuel cell power module (1) according to any one of the preceding claims including: an air supply system (13) for supplying air to the oxidant supply system (114); a water draining system (14) including a water drain connector (141).

6. The fuel cell power module (1) according to any one of the preceding claims wherein the metal hydride material has a hydrogen equilibrium pressure below 15 bar (1.5 MPa) at the ambient temperature and above 20 bar (2 MPa) at the temperature of 50 °C.

7. The fuel cell power module (1) according to claim 6 wherein the metal hydride material is a multicomponent intermetallic alloy of ABs- or AB2-type characterised by the reversible hydrogen storage capacity above 120 normal litres H2 per 1 kg of the alloy when absorbing hydrogen at the temperature below 20°C and pressure above 20 bar (2 MPa) and desorbing hydrogen at the temperature of 50°C and the pressure of 20 bar (2 MPa).

8. The fuel cell power module (1) according to any one of the preceding claims wherein the metal hydride container cooling supply system (165) provides circulation of a liquid coolant, themetal hydride container cooling supply system including a circulation pump (1651) and an extension tank (1652).

9. The fuel cell power module (1) according to any one of the preceding claims wherein the metal hydride container cooling supply system (165) provides flow of chilled water through the heating and cooling arrangement (1513) of the assembly of metal hydride containers (151).

10. The fuel cell power module (1) according to any one of claims 1 to 9 wherein the metal hydride container cooling supply system (165) provides flow of an air-water spray through the heating and cooling arrangement (1513) of the assembly of metal hydride containers (151).

11. The fuel cell power module (1) according to claim 9 or 10 wherein the metal hydride container cooling supply system (165) is configured to receive a supply of the chilled water or air-water spray (1653) via a connecting pipeline (1654) connected to the water drain connector (141) of the fuel cell powder module, and hence from a water collection system (116) of the fuel stack arrangement (11).

12. A fuel cell vehicle including the fuel cell module (1) of any one of the preceding claims.

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