GB2624701A

GB2624701A - A fuel cell system

Info

Publication number: GB2624701A
Application number: GB2217818.0A
Authority: GB
Inventors: Tinmouth Neil
Original assignee: Acua Ocean Ltd
Current assignee: Acua Ocean Ltd
Priority date: 2022-11-28
Filing date: 2022-11-28
Publication date: 2024-05-29
Also published as: WO2024115870A1; GB202217818D0

Abstract

A fuel cell system 100 for a marine vehicle, such as an unmanned surface vehicle (10, Figure 1), includes a fuel cell 29 and a coolant circuit. A fuel cell heat exchanger 110 is in thermal contact with the fuel cell to transfer heat from the fuel cell to the coolant flow path. The coolant output 112b of the fuel cell heat exchanger is connected to the coolant input 114a of a cooler 114 which is in thermal contact with a part of the marine vehicle that is submerged in water so that the heat is transferred to the sea water. The coolant output 114b of the cooler is connected to a coolant input 110a’ of a fuel heat exchanger 110 which transfers heat from the coolant passing through a coolant flow path to fuel which passes through a fuel flow path. The coolant output 110b’ of the fuel heat exchanger is connected to the coolant input 112a of the fuel cell heat exchanger. In a second fuel cell system the coolant output of the cooler is connected to a coolant input (1140a, Figure 8) of a cooling apparatus (1140b, Figure 8).

Description

A FUEL CELL SYSTEM

Field

The present invention relates to a fuel cell system for a marine vehicle. In particular, the present invention relates to a fuel cell system including a coolant circuit.

Background

Marine vehicles traditionally have propulsion systems that use petroleum fuels, particularly diesel fuels, as a source of energy. Due to the effects of climate change, there is a need to find alternative solutions that do not require petroleum fuels, or at least decrease the amount of petroleum fuels required to operate marine vehicles.

One solution has been to utilise fuel cells, typically hydrogen fuel cells, to produce energy for propulsion systems in marine vehicles. Fuel cells whether used alone or as part of a hybrid solution lessen the amount of carbon produced compared to a system solely using petroleum fuels.

Fuel cells, particularly larger fuel cells, require cooling systems to maintain the correct temperature across the fuel cell stacks and/or remove excess heat generated by the fuel cells during use.

There is a need to provide an improved fuel cell system for a marine vehicle.

Summary of Invention

According to an aspect of the present invention we provide a fuel cell system for a marine vehicle including: a fuel cell; a coolant circuit including: a first heat exchanger; a second heat exchanger; and a third heat exchanger, wherein the first heat exchanger includes: a first input for receiving a fuel, a first output for said fuel and a fuel flow path therebetween; and a second input for receiving a first coolant, a second output for said first coolant and a first coolant flow path therebetween; wherein the first heat exchanger is configured to transfer heat from the first coolant passing through the first coolant flow path to the fuel passing through the fuel flow path during use; wherein the second heat exchanger includes.

a first input for receiving the first coolant, a first output for said first coolant and a first coolant flow path therebetween; and wherein the second heat exchanger is in thermal contact with the fuel cell so that heat is transferred from the fuel cell to the first coolant passing through the first coolant flow path of the second heat exchanger during use; wherein the third heat exchanger includes: a first input for receiving first coolant, a first output for said first coolant and a first coolant flow path therebetween; and wherein, during use of the marine vehicle, the third heat exchanger is in thermal contact with a part of the marine vehicle that is submerged in water so that heat from the first coolant passing through the first coolant flow path is transferred to the water; wherein the system is arranged such that: the first output of the first heat exchanger is connected to the fuel cell to transfer fuel to the fuel cell during use; the second output of the first heat exchanger is connected to the first input of the second heat exchanger; the first output of the second heat exchanger is connected to the first input of the third heat exchanger; and the first output of the third heat exchanger is connected to the second input of the first heat exchanger.

Optionally or preferably the fuel cell system includes: wherein the second heat exchanger has a second input for receiving a second coolant, a second output for said second coolant and a second coolant flow path therebetween; wherein the fuel cell includes: a first input connected to the second output of the second heat exchanger for receiving the second coolant therefrom; a first output connected to the second input of the second heat exchanger for the second coolant to be received by the second heat exchanger; and a second coolant flow path therebetween so that heat is transferred from the fuel cell to the second coolant passing through the second coolant flow path of the fuel cell during use, wherein the second heat exchanger is configured to transfer heat from the second coolant passing through the second coolant flow path of the second heat exchanger to to the first coolant passing through the first coolant flow path of the second heat exchanger.

Optionally or preferably wherein the coolant circuit includes: a fourth heat exchanger including a first input for receiving the first coolant, a first output for said first coolant, and a first coolant flow path therebetween; and a branched flow path in between the first heat exchanger and the second heat exchanger connected to the first input of the fourth heat exchanger, wherein the fourth heat exchanger is in thermal contact with an auxiliary system of the marine vehicle during use so that heat is transferred from the auxiliary system to the first coolant passing through the first coolant flow path of the fourth heat exchanger, and the first output of the fourth heat exchanger is connected to the first input of the third heat exchanger.

Optionally or preferably wherein the fourth heat exchanger has a second input for receiving a third coolant, a second output for said third coolant and a third coolant flow path therebetween; wherein the auxiliary system includes: a first input connected to the second output of the fourth heat exchanger for receiving the third coolant therefrom; a first output connected to the second input of the fourth heat exchanger for the third coolant to be received by the fourth heat exchanger; and a third coolant flow path therebetween so that heat is transferred from the auxiliary system to the third coolant passing through the third coolant flow path of the auxiliary system during use; wherein the fourth heat exchanger is configured to transfer heat from the third coolant passing through the third coolant flow path of the fourth heat exchanger to the first coolant passing through the first coolant flow path of the fourth heat exchanger.

Optionally or preferably the fuel cell system includes a cooling apparatus for cooling the first coolant; wherein the cooling apparatus includes: an input connected to the second output of the first heat exchanger to receive the first coolant therefrom during use; and an output connected to the first input of the second heat exchanger to permit the cooled first coolant to be sent thereto during use.

Optionally or preferably the cooling apparatus is positioned in between the first heat exchanger and the branched flow path so that the output of the cooling apparatus is connected to the first input of the fourth heat exchanger to permit cooled first coolant to be sent thereto during use.

Optionally or preferably the cooling circuit includes: one or more valves to permit one or more configurations of the cooling circuit, wherein, for each configuration the first coolant flows along a respective path through one or more of the first, second, third and, optionally fourth, heat exchangers; and/or one or more temperature sensors for measuring the temperature of the first coolant at respective positions of the cooling circuit; and a control device for controlling the fuel cell system; wherein the control device is configured to control the one or more valves to place the cooling circuit into one of the one or more configurations of the cooling circuit, and/or change the flow rate of the first coolant through one or more of the first, second, third and fourth heat exchangers.

Optionally or preferably the control device is configured to receive temperature signal(s) from the one or more temperature sensors and the control device is configured to change the configuration of the cooling circuit and/or flow rate based on the received temperature signal(s).

Optionally or preferably the one or more configurations include a first configuration, for when the fuel cell is on, in which the first coolant passes through the first, second, and third heat exchangers, and the flow rate of the first coolant through the third heat exchanger is adjusted based on the temperature of the water to change the amount of heat transfer from the first coolant passing through the third heat exchanger.

Optionally or preferably the first configuration includes the first coolant passing through the fourth heat exchanger.

Optionally or preferably the one or more configurations include a second configuration in which the first coolant only passes through the third heat exchanger and the fourth heat exchanger, and the control device is configured to place the coolant circuit into the second configuration when the fuel cell is off.

Optionally or preferably the first configuration includes the first coolant passing through the cooling apparatus, and when the coolant circuit is in the first configuration, the control device is configured so that if the control device determines that the temperature of the first coolant at the second output of the first heat exchanger is below or at a pre-determined temperature, the fuel cell system is operated with the cooling apparatus off, and if the control device determines that the temperature is above the pre-determined temperature, the fuel cell system is operated with the cooling apparatus on.

Optionally or preferably the second configuration includes the first coolant passing through the cooling apparatus, and wherein the control device is configured so that, when the coolant circuit is in the second configuration, if the control device determines that the temperature of the first coolant at the output of the third heat exchanger is below or at a pre-determined temperature, the fuel cell system is operated with the cooling apparatus off, and if the control device determines that the temperature is above the pre-determined temperature, the fuel cell system is operated with the cooling apparatus on.

Optionally or preferably the control device is configured to adjust the flow rate of the first coolant through the first, second, third and/or fourth heat exchanger so that a pre-determined amount of heat is transferred to or from the first coolant at the respective first, second, third and/or fourth heat exchanger.

Optionally or preferably the control device is configured to optimise the amount of heat transfer so that the amount of energy expended by the cooling apparatus required to cool the first coolant is minimised.

Optionally or preferably the cooling circuit includes a first valve positioned between the first heat exchanger and the second heat exchanger, the first valve including: an input for receiving the first coolant flowing downstream of the second output of the first heat exchanger, a first output for said first coolant and a second output for said first coolant, wherein the system is arranged such that: the input of the first valve is connected to the second output of the first heat exchanger, the first output of the first valve is connected to the first input of the second heat exchanger; the second output of the first valve is connected to the first input of the fourth heat exchanger by the branched flow path extending therebetween, wherein the first valve is controlled by the control device to permit the first coolant to flow to one or both of the second and fourth exchangers.

io Optionally or preferably the input of the first valve is connected to the output of the cooling apparatus to receive cooled first coolant therefrom during use.

Optionally or preferably the cooling circuit includes a second valve positioned between the first heat exchanger and the first valve, wherein the second valve includes a first input for receiving the first coolant, a second input for receiving the first coolant and an output for said first coolant; and a branched flow path downstream of the third heat exchanger and upstream of the second inlet of the first heat exchanger, wherein the system is arranged such that: the first input of the second valve is connected to the outlet of the third heat exchanger to received cooled first coolant therefrom; the second input of the second valve is connected to the second output of the first heat exchanger to receive cooled first coolant therefrom; and the output of the second valve is connected to the input of the first valve, wherein the second valve is controlled by the control device so that the first coolant flows from only one of the first input or the second input to the first valve.

Optionally or preferably the cooling apparatus is positioned in between the second valve and the first valve so that the output of the second valve is connected to the first input of the cooling apparatus and the first output of the cooling apparatus is connected to the input of the second valve to receive cooled therefrom during use.

Optionally or preferably the fuel cell system includes: a third valve including an input for receiving the first coolant, a first output for said first coolant and a second output for said first coolant, wherein the system is arranged such that: the input of the third valve is connected to the first outlet of the third heat exchanger to receive coolant first coolant therefrom; the first output of the third valve is connected to the second input of the first heat exchanger; the second output of the third valve is connected to the input of the first valve, wherein the third valve is controlled by the control device so that the first coolant flows only from one of the first and second outputs of the third valve.

Optionally or preferably the cooling circuit includes a first temperature sensor positioned lo downstream of the first output of the second heat exchanger and upstream of the third heat exchanger to measure the temperature of the first coolant outputted at the first output of the second heat exchanger.

Optionally or preferably the cooling circuit includes a second temperature sensor positioned downstream of the first output of the third heat exchanger and upstream of the first heat exchanger to measure the temperature of the cooled first coolant outputted at the first output of the third heat exchanger.

Optionally or preferably the cooling circuit includes a third temperature sensor positioned downstream of the second output of the first heat exchanger and upstream of the second heat exchanger to measure the temperature of the cooled first coolant outputted at the second output of the first heat exchanger.

Optionally or preferably the cooling circuit includes a fourth temperature sensor positioned for measuring the temperature of the water outside the marine vehicle during use, and wherein the control device is configured to adjust the flow rate of the first coolant through the third heat exchanger based on the temperature.

A fuel cell system according to any preceding aspect wherein the third heat exchanger includes: one or more tubes along which the first coolant flows during use and are arranged so that, in use, the one or more tubes are in thermal contact with the surface of the marine vehicle that is in contact with the water so that heat is transferred from the first coolant to the water.

According to an aspect of the present invention we provide a fuel cell system for a marine vehicle including: a fuel cell; a coolant circuit connected to the fuel cell, and the coolant circuit including: a first heat exchanger; a second heat exchanger, a cooling apparatus; wherein the first heat exchanger includes: a first input for receiving the first coolant, a first output for said first coolant and a first coolant flow path therebetween, wherein the first heat exchanger is in thermal contact with the fuel cell so that heat is transferred from the fuel cell to the first coolant flow path, and io wherein the second heat exchanger includes: a first input for receiving first coolant, a first output for said first coolant and a first coolant flow path therebetween; and wherein, during use of the marine vehicle, the second heat exchanger is in thermal contact with a part of the marine vehicle that is submerged in water so that heat from the first coolant passing through the first coolant flow path is transferred to the water; wherein the cooling apparatus has a first input for receiving the first coolant, a first output for the first coolant and a first coolant flow path therebetween; wherein the system is arranged such that: the first output of the first heat exchanger is connected to the first input of the second heat exchanger; the first output of the second heat exchanger is connected to the first input of the cooling apparatus; and the first output of the cooling apparatus is connected to the first input of the first heat exchanger.

Optionally or preferably the fuel cell system includes: a second coolant; wherein the first heat exchanger has a second input for receiving the second coolant, a second output for said second coolant and a second coolant flow path 30 therebetween; wherein the fuel cell has a first input for receiving the second coolant, a first output for said second coolant and a second coolant flow path therebetween so that heat is transferred from the fuel cell to the second coolant flow path; wherein the first heat exchanger is configured to transfer heat from the second coolant passing through the second coolant flow path to the first coolant passing through the first coolant flow path; wherein the system is arranged such that: the second output of the first heat exchanger is connected to the first input of the fuel cell; and the first output of the fuel cell is connected to the second input of the first heat exchanger.

Optionally or preferably the coolant circuit includes: a third heat exchanger including a first input for receiving the first coolant, a first output for said first coolant, and a first coolant flow path therebetween; and a branched flow path in between cooling apparatus and the first heat io exchanger connected to the first input of the third heat exchanger, wherein the third heat exchanger is in thermal contact with an auxiliary system of the marine vehicle during use so that heat is transferred from the auxiliary system to the first coolant passing through the first coolant flow path of the third heat exchanger, and the first output of the third heat exchanger is connected to the first input of the second heat exchanger.

Optionally or preferably the coolant circuit includes a first valve positioned between the cooling apparatus and the first heat exchanger, wherein the first valve has an input connected to the output of the cooling apparatus, a first output connected to the first input of the first heat exchanger and a second output connected to the branched flow path upstream of the third heat exchanger, and wherein the first valve may be operated to for direct the first coolant one or both of the first heat exchanger and the third heat exchanger.

Optionally or preferably the third heat exchanger has a second input for receiving a third coolant, a second output for said third coolant and a third coolant flow path therebetween; wherein the auxiliary system includes: a first input connected to the second output of the third heat exchanger for receiving the third coolant therefrom; a first output connected to the second input of the third heat exchanger for the third coolant to be received by the third heat exchanger; and a third coolant flow path therebetween so that heat is transferred from the auxiliary system to the third coolant passing through the third coolant flow path of the auxiliary system during use; wherein the third heat exchanger is configured to transfer heat from the third coolant passing through the third coolant flow path of the fourth heat exchanger to the first coolant passing through the first coolant flow path of the fourth heat exchanger.

Optionally or preferably the first coolant and second coolants are different coolants, and optionally or preferably the second and third coolants are the same coolant, or the first, second and third coolants are different coolants.

Optionally or preferably the fuel is hydrogen.

Optionally or preferably the fuel is stored at cryogenic temperatures.

A fuel cell system according to any preceding aspect including: a fuel tank, and a heating element for heating the fuel.

According to an aspect of the present invention we provide a marine vehicle including a fuel cell system according to any preceding aspect, optionally or preferably the marine vehicle including a or the auxiliary system.

Brief Description of Drawings

Embodiments will now be described, by way of example only and with reference to the accompanying drawings having like-reference numerals, in which: Embodiments of the invention will be set out below by way of example only with reference to the accompanying figures, of which: Figure 1 is a perspective view of a marine vehicle embodying an aspect of the present disclosure; Figure 2 is a side view of the marine vehicle shown in figure 1; Figure 3 is a schematic view of the marine vehicle shown in figure 1 with certain components of a fuel cell system of the marine vehicle shown thereof; Figure 4 is a cross-section view of a certain portion of the marine vehicle shown in figure 1; Figure 5 is a schematic cross-section view of a certain part of the marine vehicle shown in figure 1; Figure 6a is a schematic transverse cross-section view of the part shown in figure 5; Figure 6b is a schematic view of a component of the part shown in figure 6a; Figure 7 is a schematic layout of a fuel cell system of the marine vehicle shown in figure 1

embodying an aspect of the present disclosure; and

Figure 8 is a schematic layout of a fuel cell system of the marine vehicle shown in figure 1 embodying another aspect of the present disclosure.

Specific Description

With reference to the figures 1 to 6a, 6b, a marine vehicle 10 and certain components thereof are shown. In this example, the marine vehicle 10 is an unmanned surface vehicle (USV) but it should be understood that any type of marine vehicle could be used without departing from the scope of the present disclosure.

The marine vehicle includes a hull 11, elongate arms 12a, 12b, 12c, 12d, and first and second vessel parts 14a, 14b.

The hull 11 includes first and second parts 11a, 11 b connected together and positioned at opposite ends of the marine vehicle 10. The first and second parts 11a, llb are identical, and so only the first part 11 a will be described with common features of the second part 11 b being denoted by the same reference numeral with the suffix 'a' replaced by 'b. The first part 11 a is generally obround in shape and has a recessed section at one of its sides that faces towards the second part 11 b. The first part 11 a has a right side 13a and a left side 15a. The first part lla defines an internal space for housing operative components of the marine vehicle 10.

Elongate arms 12a, 12b, 12c, 12d are identical and connect the first and second parts 11a, llb to the first and second vessel parts 14a, 14b so that the first and second vessel parts 14a, 14b are vertically spaced apart and below the first and second parts 11a, 11b.

A first end of elongate arm 12a is connected to the right side 13a of the first part 11a, and a second, opposite, end of the first elongate arm 12a is connected to a corresponding end of the first vessel part 14a. A first end of elongate arm 12b is connected to the left side 15a of the first part 11a, and a second, opposite, end of the first elongate arm 12b is connected to a corresponding end of the second vessel part 14b. The left side 15a is connected to one end of a second elongate arm 12b, and an opposite end of the second elongate arm 12b is connected to a corresponding end of the second vessel part 14b. Elongate arms 12c, 12b are connected to the second part 11 b and the first and second vessel parts 14a, 14b in a similar way. During use of the marine vehicle, the first and second vessel parts 14a, 14b are submerged in water with the hull 11 spaced above the water line, and the elongate arms 12a to 12d extend between them.

In this example, the hull 11 houses a fuel cell 29 and auxiliary system 30 which may include one or more of an energy storage system, e.g. an electric battery, computer devices, e.g. servers and computers, and/or other devices for performing operations on the marine vehicle 10. These components are housed within the internal spaces of the first and second parts 11a, 11b. The hull 11 may include redundancy components, e.g. separate fuel cells, auxiliary systems and other devices located in each part 11a, 1 lb for use should one of the components fail or be unavailable for operation for other reasons, e.g. maintenance.

The first and second vessel parts 14a, 14b each include a fuel tank 21a, 21b, a propulsion device (not shown), e.g. a propeller, and a propulsion drive device (not shown), e.g. a thruster, for driving the propulsion device. The fuel tanks 21a, 21b store fuel for use by the fuel cell 29 to generate electricity which is used to power operation of the auxiliary system 30 and the propulsion drive device. The first and second vessel parts 14a, 14b are identical and generally cylindrical in shape. The ends of the vessel parts 14a, 14b to which the elongate arm 12a, 12b are connected are generally frusto-conical shaped and taper as they extend away from the rest of the respective parts 14a, 14b.

With reference to figure 3, this is a schematic view showing the first part ha of the hull 11, elongate arm 12a, and first vessel part 14a. The elongate arm 12a defines an internal space for a fuel line 23, a coolant line 24, a power line 25 and a data line 26. The fuel cell 29 is connected to the fuel tank 21a by the fuel line 23 for fuel to flow along to the fuel cell 29. The coolant line 25 connects the fuel cell 29 to a coolant as will be described in more detail below.

The power line 25 permits electricity to flow from an energy storage system of the auxiliary system 30 to components in the first vessel part 14a that require it, for example, the propulsion drive device. The data line 26 permits information to be transferred between devices of the auxiliary system 30, e.g. computing equipment, and components in the first vessel part 14a.

Figure 4 shows the lines 23 to 26 passing internally through the elongate arm 12a. The elongate arm 12b may similarly include respective lines which connect respective components in the second vessel part 12b to the components in the first part 11a. The second part 11 b of the hull may be similarly configured. It should be understood that multiple lines 24 to 27 may be provided along the elongate arms 12a to 12d and/or be variously connected to components in the first and/or second vessel parts 14a, 14b according to different configurations of marine vehicle 10. The lines may be configured according to the requirements and specification of the particular marine vehicle 10. Similarly, it should be understood that, in examples, the fuel cell 29 and/or components of the auxiliary system 30 may be located in other parts of the marine vehicle 10, e.g. in one or both of the first and second vessel parts 14a, 14b.

In this example, the fuel cell 29 is a hydrogen polymer electrolyte membrane (PEM) fuel cell and the fuel stored in the fuel tanks 21a, 21b is hydrogen. It should be understood that, in other examples, different fuel cell technologies and/or fuels may be used.

Referring to figure 7, this schematically shows a fuel cell system 100 of the marine vehicle 10.

The fuel cell system 100 includes the fuel cell 29 and a coolant circuit shown by solid arrows.

The coolant circuit includes a first heat exchanger 110, a second heat exchanger 112, and a third heat exchanger 114. The coolant circuit, when in use, contains a first coolant in order to transfer heat at the heat exchangers 110, 112, 114 as will be described. In examples, the first coolant may be any liquid or gas suitable for use in heat transfer. In the present example, the first coolant may be a relatively highly dilute mixture of water and glycol. The coolant circuit may be arranged to only cool the fuel cell 29, or to cool one or both of the fuel cell 29 and auxiliary system 30.

The first heat exchanger 110 includes a first input 110a for receiving a fuel, a first output 110b for said fuel and a fuel flow path therebetween shown in figure 7 by a dotted line. The first heat exchanger 110 may also be referred to as a fuel heat exchanger 110. The first input 110a is connected to the fuel tanks 21a, 21b to receive fuel therefrom, and the first output 110b is connected to the fuel cell 29 to transfer fuel to the fuel cell 29 during use. The first exchanger 110 includes a second input 110a' for receiving the first coolant, a second output 110b' for said first coolant and a first coolant flow path therebetween. The first heat exchanger 110 is configured to transfer heat from the first coolant passing through the first coolant flow path to the fuel passing through the fuel flow path during use.

The second heat exchanger 112 includes a first input 112a for receiving the first coolant, a first output 112b for said first coolant, and a first coolant flow path therebetween. The second heat exchanger 112 may also be referred to as a fuel cell heat exchanger 112. The second heat exchanger 112 is in thermal contact with the fuel cell 29 so that heat is transferred from the fuel cell 29 to the first coolant passing through the first coolant flow path of the second heat exchanger 112 during use.

The third heat exchanger 114 includes a first input 114a for receiving the first coolant, a first output 114b for said first coolant and a first coolant flow path therebetween. the third heat exchanger 114 may be referred to as a cooler 114. During use of the marine vehicle 10, the third heat exchanger 114 is in thermal contact with the water in which the vessel 10 is floating or a part of the marine vehicle, e.g. the outer skins of the first and second vessel parts 14a, 14b, that is submerged in water so that heat from the first coolant passing through the first coolant flow path of the third heat exchanger 114 is transferred to the water. Thermal contact herein is taken to mean a close association that allows efficient transfer of thermal energy for example in this case between the first coolant in the third heat exchanger 114and the water in which the boat is floating. This may be by close association, which may include a means for aiding heat transfer such as a heat transfer compound or complementary surfaces to ensure contact over a large area.

An example of the third heat exchanger 114 for use with the fuel cell system is shown in figures 5, 6a and 6b. The third heat exchanger 114 is provided in the first and second vessel parts 14a,b and is in contact with the inner surface of the outer skins 33a, 33b of the respective vessel parts 14a, b. The third heat exchanger 114 is formed of respective sections of coiled tubes 32 through which the first coolant flows. The coiled tubes 32 extend longitudinally along the length of the first vessel parts 14a, 14b. In examples, as shown in figure 6a, the fuel tank 21a may be positioned centrally of the first vessel part 14a and the third heat exchanger 114 positioned in a space 34 between the fuel tank 21a and the outer skin of the vessel part 14a.

In examples, the third heat exchanger 114 may only be provided in one of the vessel parts 14a, 14b. In examples, the third heat exchanger 114 may have alternative configurations or designs and may be in thermal contact with any submerged part of the marine vehicle 10.

According to an aspect of the present disclosure, the system is arranged such that the second output 110b' of the first heat exchanger 110 is connected to the first input 112a of the second heat exchanger 112. The first output 112b of the second heat exchanger 112 is connected to the first input 114a of the third heat exchanger 114 and the first output 114b of the third heat exchanger 114 is connected to the second input 110a' of the first heat exchanger 110.

In this example, in accordance with the present disclosure, the fuel cell system 100 includes a cooling apparatus 140 positioned between the first heat exchanger 110 and the second heat exchanger 112. The cooling apparatus 140 may be one or more chillers located in the marine vehicle 10, e.g. in the hull. The cooling apparatus 140 may be fluidly connected to the coolant circuit to cool the first coolant. The cooling apparatus 140 may be connected to an energy storage system of the auxiliary system 30 to receive the energy it needs therefrom to operate and cool the first coolant. The cooling apparatus 140 may have an input 140a connected to the second output 110b' of the first heat exchanger 110 to receive the first coolant therefrom during use, and an output 140b connected to the first input 112a of the second heat exchanger to permit the cooled first coolant to be sent thereto during use. The cooling apparatus 140 may be positioned between the first heat exchanger 110 and a branched flow path 130, (as will be described), so that the output 140b of the cooling apparatus 140 is also fluidly connected to the first input 116a of the fourth heat exchanger 116 to permit cooled first coolant to be sent thereto during use.

The term connection or flow path is used to denote a fluid connection or fluid tight connection for transferring a fluid such as coolant or fuel between two points. The fuel cell system 100 includes a series of such connections or conduits, e.g. pipes or hoses, e.g. including fuel line 23 and coolant line 24 that connect the components of the fuel cell system 100 together and provide fluid paths between the components. In examples, flow meters may be provided in the conduits to monitor the flow of fluid at different points along the coolant circuit. The coolant circuit is a closed circuit in that the first coolant does not leave the closed circuit during use.

However, the coolant circuit may include valves for draining coolant from, or feeding coolant to, the coolant circuit, e.g. to pressurise or depressurise the coolant circuit.

In this example, the fuel tanks 21a, 21b store the fuel as a liquid stored at cryogenic temperatures. Liquified fuel has the advantage of higher energy density than other storage methods, however the fuel must be stored at low temperatures. The marine vehicle 10 includes means (e.g. located in the first and second vessel parts 14a, 14b) for maintaining the temperature of the fuel within the fuel tanks 21a, 21b at this temperature. When the fuel is to be used by the fuel cell 29, the fuel must be heated until it changes phase to a gaseous state and is at the correct temperature for use by the fuel cell 29. In this example, the fuel is heated to a gaseous state through the use of heating elements 21a', 21b' situated within the fuel tanks 21a, 21b. The fuel, in its gaseous state, is provided to the first input 110a of the first heat exchanger 110 and, as will be described, is further heated as it passes along the fuel flow path to reach the correct temperature for use downstream by the fuel cell 29.

The second heat exchanger 112 may be integrally formed as part of the fuel cell 29 itself and in thermal contact with the rest of the fuel cell 29, or may be a separate component part that is in thermal contact with the fuel cell 29. In either case, the second heat exchanger 112 may, in examples, be provided with a second input 112a' for receiving a second coolant, a second output 112b' for said second coolant and a second coolant flow path therebetween shown in figure 7 by a dashed line. The fuel cell 29 may include a first input 29a connected to the second output 112b' of the second heat exchanger 112 for receiving the second coolant therefrom, and a first output 29b connected to the second input 112b' of the second heat exchanger 112 for the second coolant to be received by the second heat exchanger 112. The fuel cell 29 may include a second coolant flow path between the first input 29a and the second output 29b so that heat is transferred from the fuel cell 29 to the second coolant passing through the second coolant flow path of the fuel cell 29 during use. The second heat io exchanger 112 may be configured to transfer heat from the second coolant (received from the fuel cell 29) passing through the second coolant flow path of the second heat exchanger 112 to the first coolant passing through the first coolant flow path of the second heat exchanger 112. The fuel cell 29 is thus cooled through the use of the second heat exchanger 112 and heat is transmitted therefrom to the first coolant. Heat within the fuel cell is thus transferred to the second coolant that passes through the second coolant path of the second heat exchanger 112, and then transferred to the first coolant passing through the first coolant path of the second heat exchanger 112. In this way, the fuel cell 29 is connected to the second heat exchanger 112 in a first closed loop along which the second coolant flows and absorbs heat from the fuel cell, whilst heat is then transferred from the second coolant to the first coolant at the second heat exchanger 112. This permits the first and second coolants to be different substances. For example, the second coolant may be a relatively high concentration glycol based coolant, e.g. EC G20 liquid, to permit its use with the fuel cell 29 without causing any damage thereto. Such a coolant may be more expensive and high performance in comparison to the first coolant. By having the second coolant run along a closed loop between the fuel cell 29 and the second heat exchanger 112, a relatively small amount of the second coolant may be required compared to having the second coolant run through the entire cooling circuit of the fuel cell system 100. However, in examples, the first and second coolants may be identical coolants.

In this example, where the marine vehicle 10 includes an auxiliary system 30, the coolant circuit 100 may include a fourth heat exchanger 116 for use in transferring heat from the auxiliary system 30 to the first coolant. The fourth heat exchanger 116 includes a first input 116a for receiving the first coolant, a first output 116b for said first coolant, and a first coolant flow path therebetween. The fourth heat exchanger 116 may also be referred to as a auxiliary systems heat exchanger 116.

The coolant circuit includes the branched flow path 130 in between the first heat exchanger 110 and the second heat exchanger 112. The branched flow path 130 is connected to the first input 116a of the fourth heat exchanger 116. The branched flow path 130 is downstream of the second output 110b' of the first heat exchanger 110 and upstream of the first input 112a of the second heat exchanger 112. The fourth heat exchanger 116 is in thermal contact with the auxiliary system 30 during use so that heat is transferred from the auxiliary system 30 to the first coolant passing through the first coolant flow path of the fourth heat exchanger 116, and the first output 116b of the fourth heat exchanger 116 is connected to the first input 114a of the third heat exchanger 114.

In examples, similar to the second heat exchanger 112, the fourth heat exchanger 116 may have a closed loop between it and the auxiliary system 30 for a third coolant, and the fourth heat exchanger 116 may be configured to transfer heat from the auxiliary system 30 to the third coolant, and to transfer heat from the third coolant to the first coolant passing through the fourth heat exchanger 116. In such examples, the fourth heat exchanger 116 has a second input 116a' for receiving a third coolant, a second output 116b' for said third coolant and a third coolant flow path therebetween shown on figure 7 by a dashed line. The auxiliary system 30 includes a first input 30a connected to the second output 116b' of the fourth heat exchanger for receiving the third coolant therefrom, a first output 30b connected to the second input 116a' of the fourth heat exchanger 116 for the third coolant to be received by the fourth heat exchanger 116, and a third coolant flow path therebetween so that heat is transferred from the auxiliary system 30 to the third coolant passing through the third coolant flow path of the auxiliary system 30 during use. The fourth heat exchanger 116 is configured to transfer heat from the third coolant passing through the third coolant flow path of the fourth heat exchanger 116 to the first coolant passing through the first coolant flow path of the fourth heat exchanger 116. The third coolant may be similar or the same as the second coolant, and/or identical to the first coolant.

The cooling circuit may include valves 150, 160, 170 to permit one or more configurations of the cooling circuit. For each configuration, the first coolant flows along a respective path through one or more of the first, second, third and/or fourth heat exchangers 110, 112, 114, 116. The cooling circuit may also include temperature sensors 161, 162, 164, 166, 168, 169 for measuring the temperature of the first coolant at respective positions of the cooling circuit. The fuel cell system 100 may include a control device for controlling the fuel cell system 100 and components thereof. The control device may be configured to control the valves 150, 160, 170 and/or change the flow rate of the first coolant through the cooling circuit, e.g. by changing the setting of the valves 150, 160, 170 or adjusting operation of the first, second, third and/or fourth heat exchangers 110, 112, 114, 116 so that the rate of flow of the first coolant therethrough is changed.

The control device may be configured to receive temperature signals from the temperature sensors 161-169 and to change the configuration of the cooling circuit and/or flow rate of the first coolant through the cooling circuit based on the received temperature signals.

In more detail, first valve 150 may be positioned between the first heat exchanger 110 and the second heat exchanger 112, and downstream of the cooling apparatus 140. The first valve 150 may include an input 150a for receiving the cooled first coolant from the cooling apparatus 140, a first output 150b for said first coolant and a second output 150b' for said first coolant. The input 150a of the first valve 150 is connected to the output 140b of the cooling apparatus 140. The first output 150b of the first valve 150 is connected to the first input 112a of the second heat exchanger 112. The second output 150b' of the first valve 150 is connected to the first input 116a of the fourth heat exchanger 116 by the branched flow path 130 extending therebetween. The first valve 150 is controlled by the control device to permit the first coolant to flow to one or both of the second and fourth exchangers 112, 116. In examples where the cooling apparatus 140 is not provided, the input 150a of the first valve 150 is connected to the second output 110b' of the first heat exchanger 110 directly.

The second valve 160 may be positioned between the first heat exchanger 110 and the first valve 150 with the cooling apparatus 140 positioned between the second valve 160 and the first valve 150. The second valve 160 may include a first input 160a for receiving the first coolant, a second input 160a' for receiving the first coolant and a second output 160b for said first coolant. The cooling circuit may include a branched flow path 130' downstream of the third heat exchanger 114 and upstream of the second inlet 110b' of the first heat exchanger 110. The first input 160a of the second valve 160 is connected to the output 114b of the third heat exchanger 114 via the branched flow path 130' to received cooled first coolant therefrom. The second input 160a' of the second valve 160 is connected to the second output 110b' of the first heat exchanger 110 to receive cooled first coolant therefrom. The output 160b of the second valve 160 is connected to the input 140a of the cooling apparatus 140. The second valve 160 is controlled by the control device so that the first coolant flows from only one of the first input 160a or the second input 160a' to the first valve 150 / cooling apparatus 140.

The third valve 170 may include an input 170a for receiving the first coolant, a first output 170b for said first coolant and a second output 170b' for said first coolant. The input 170a of the third valve 170 is connected to the first outlet 114b of the third heat exchanger 114 to receive coolant first coolant therefrom. The first output 170b of the third valve 170 is connected to the second input 110a' of the first heat exchanger 110. The second output 170b' of the third valve 170 is connected to the input 160a of the second valve 160. The third valve 170 is controlled by the control device so that the first coolant flows only from one of the first and second outputs 170b, 170b' of the third valve 170 to the first heat exchanger 110 or the second valve 160.

A first temperature sensor 161 is positioned downstream of the first output 112b of the second heat exchanger 112 and upstream of the third heat exchanger 114 to measure the temperature of the first coolant outputted at the first output 112b of the second heat exchanger 112.

A second temperature sensor 162 is positioned downstream of the first output 114b of the third heat exchanger 114 and upstream of the first heat exchanger 110 to measure the temperature of the cooled first coolant outputted at the first output 114b of the third heat exchanger 114.

A third temperature sensor 164 is positioned downstream of the second output 110b' of the first heat exchanger 110 and upstream of the second heat exchanger 112 to measure the temperature of the cooled first coolant outputted at the second output 110b' of the first heat exchanger 110.

The cooling circuit includes a fourth temperature sensor 166 positioned for measuring the temperature of the water outside the marine vehicle 10 during use. The control device may be configured to adjust the flow rate of the first coolant through the third heat exchanger 114 based on the temperature at sensor 166.

In examples where a cooling apparatus 140 is provided, a fifth temperature sensor 168 is positioned downstream of the output of the cooling apparatus 140 and upstream of the first input of the second heat exchanger 112. Where a branched path 130 is provided, the sensor 168 may be positioned upstream of the branched path 130.

In examples where a fourth heat exchanger 116 is provided, a sixth temperature sensor 169 is provided downstream of the first output 116b of the fourth heat exchanger 116 and upstream of the third heat exchanger 116. Furthermore, a branched flow path 130" downstream of the second outlet 112b of the second heat exchanger 112 and upstream of the third heat exchanger 114, connects the first output 116b to the third heat exchanger 114.

15 20 25 Operation of the marine vehicle 10 and the fuel cell system 100 will now be described.

The control device is configured to optimise, e.g. through the use of an algorithm, the operation of the cooling circuit based on the status of the fuel cell system 10 and operating requirements. For example, the control device may be configured to control the valves 150, 160, 170 to place the cooling circuit into different configurations and/or change the flow rate of the first coolant through one or more of the first, second, third and fourth heat exchangers 110-116 to cool one or both of the fuel cell 29 and auxiliary system 30. The control device may also receive the temperature signals from the temperature sensors 161 -169 and the control device is configured to change the configuration of the cooling circuit and/or flow rate of the first coolant based on the received temperature signal.

For example, when the fuel cell 29 is on, the control device is configured to operate the cooling circuit to cool the fuel cell 29 and/or the auxiliary system 30 with a minimum of expended energy being required.

Operation of the coolant circuit will first be described in general terms to assist in understanding the different configurations of the coolant circuit. The first coolant, when the fuel cell 29 has been operating for a sufficient time, will be heated as it passes through the second heat exchanger 112 and absorbs the heat exhausted by the fuel cell 29, as well as the auxiliary system 30 when it passes through the fourth heat exchanger 116. The first coolant then passes through the first heat exchanger 110 via the third heat exchanger 114. At the first heat exchanger 110, heat from the relatively warm first coolant is transferred to the fuel passing through the first heat exchanger 110 to advantageously warm the fuel to the required temperature for its use at the fuel cell 29, before the fuel passes to the fuel cell 29. Depending on the operating conditions, this heat transfer would not be enough to change the phase of the fuel, i.e. change liquid hydrogen to hydrogen gas, and so the fuel will still generally need to be heated by the heating elements 21a, 21b' before it reaches the first heat exchanger 110. However, the heating elements 21a', 21b' may not need to heat the fuel to the operating temperature required at the fuel cell 29, and instead may heat it to a lower temperature, if the control device determines that the relatively warm first coolant at the first heat exchanger 110 is sufficiently warm to transfer the heat required to bring the fuel to the operating temperature required. This advantageously reduces the amount of energy consumed by fuel cell system 100 because the heat exhausted by the fuel cell 29 is used to at least pre-heat the fuel at the first heat exchanger 110 and because the heating elements 21a', 21b' do not have to provide all the heating of the fuel. However, the temperature of the first coolant may need to be reduced before it reaches the first heat exchanger 110 and so, advantageously, the third heat exchanger 114 can be used to reduce the temperature of the first coolant prior to it being received by the first heat exchanger 110 rather than requiring use of a powered cooling apparatus which would otherwise consume energy that must be supplied from a source on the marine vehicle 10. The third heat exchanger 114 transfers the excess heat from the first coolant to the surrounding water, e.g. sea water, in which the marine vehicle 10 is travelling.

The control device may also adjust (e.g. through a valve upstream of the third heat exchanger 114 or an internal mechanism of the third heat exchanger 114) the flow rate of the first coolant through the third heat exchanger 114 based on the temperature of the water as measured by the temperature sensor 166. For example, if the water is at very low temperatures, the flow rate may need to be increased to avoid too much heat being lost from the first coolant as it passes through the third heat exchanger 114.

The first coolant leaving the first heat exchanger 110 then flows to the second heat exchanger 112. However, the temperature, as determined by the control device using the temperature sensor 164 downstream of the first heat exchanger 110, of the first coolant may not be low enough to achieve a satisfactory cooling of the fuel cell 29. In such a situation, the cooling apparatus 140 may be operated to achieve the additional cooling required.

When the fuel cell is off, energy may still be consumed by the auxiliary system 30, e.g. to operate computer devices or servers of the system 30 and the auxiliary system 30 may need to be cooled to avoid damage thereto. In this state, the control device is configured to direct the first coolant to the fourth heat exchanger 116 via the third heat exchanger 114 and cooling apparatus 140 using valves 150, 160, 170 without the first coolant passing through the first and second heat exchangers 110, 112. This minimises the flow path of the first coolant. Depending on the temperature of the first coolant as it leaves the third heat exchanger 114, the control device may determine that further cooling by the cooling apparatus 140 is not required and the temperature is sufficiently low enough for the first coolant to cool the auxiliary system 30. If the temperature is not sufficiently low, then the control device may operate the cooling apparatus 140. Advantageously, the use of the third heat exchanger 114 together with the cooling apparatus 140 allows for less energy to be consumed by the cooling apparatus 140 compared to if the cooling apparatus 140 was performing all the necessary cooling of the first coolant.

Operation of the coolant circuit will now be described with reference to the particular configurations thereof in more detail.

When the fuel cell 29 is on and the auxiliary system 30 requires cooling, the control device is configured to place the coolant circuit into a first configuration in which the first coolant passes through the first, second, third and fourth heat exchangers 110-116, and the cooling apparatus 140. In this configuration, the valve 170 only permits the first coolant to flow from the third heat exchanger 114 to the first heat exchanger 110 where it is cooled due to the heat from the first coolant being transferred to the fuel at the first heat exchanger 110. The first coolant then passes to the cooling apparatus 140. The cooling apparatus 140 will be turned on if the control device determines that the temperature of the first coolant at the second outlet 110b' of the first heat exchanger is above a pre-determined temperature, e.g. it is too high to provide the necessary cooling of the fuel cell 29 / auxiliary system 30 at the second heat exchanger 112, and if the temperature is below or at the pre-determined temperature to provide the necessary cooling, the cooling apparatus 140 is turned off or remains off. The first coolant then enters the second valve 160 and is outputted therefrom to the cooling apparatus 140 through which it flows to the first valve 150. At the first valve 150, the first coolant passes to the second heat exchanger 112 and also to the fourth heat exchanger via the branched path 130. The first coolant passes through the third heat exchanger 114 to absorb heat from the fuel cell 29 via the second coolant before it enters the third heat exchanger 114. Similarly, the first coolant passes through the fourth heat exchanger 116 to absorb heat from the auxiliary system 30 via the third coolant before it travels along branched flow path 130" to merge with the flow path along which the first coolant from the second heat exchanger 112 travels to the third heat exchanger 114 The third heat exchanger 114 then cools the first coolant before it travels onwards to the first heat exchanger 110 and the process repeats itself in a closed loop. It will be understood that the control device is configured to adjust the flow rate through the heat exchangers 110 -116 so that a pre-determined amount of heat is transferred to or from the first coolant so as to optimise that heat transfer and thereby minimise the amount of energy expended by the cooling apparatus 140 required to cool the first coolant for sufficient cooling of the fuel cell 29 and/or auxiliary system 30. The control device is configured to perform this optimisation by taking account of the temperature of the first coolant at the temperature sensors 161 -169.

When the fuel cell 29 is off and the auxiliary system 30 requires cooling, the control device is configured to place the cooling circuit into a second configuration in which the first coolant only passes through the third heat exchanger 114, the fourth heat exchanger 116, and cooling apparatus 140 and the control device is configured to place the coolant circuit into the second configuration when the fuel cell is off.

In the second configuration, the first coolant passes from the third heat exchanger 114 to the third valve 170. The third valve 170 is operated to output the first coolant to the second valve 160 via the branched path 130' with no first coolant being outputted to the first heat exchanger 110. The second valve 160 then outputs the first coolant to the cooling apparatus 140. The control device is configured so that if the control device determines from the temperature sensor 162 that the temperature of the first coolant at the output 114b of the third heat exchanger 114 is below or at a pre-determined temperature sufficient for cooling the auxiliary system 30, then the cooling apparatus 140 is turned off or remains off. However, if the control device determines that the temperature of the first coolant is above the pre-determined temperature, the cooling apparatus 140 is turned on. The control device is configured to operate the first valve 150 so as to direct all the first coolant to the fourth heat exchanger 116 via the branched path 130. The first coolant then passes through the fourth heat exchanger 116 to cool the auxiliary system 30, before flowing to the third heat exchanger 114 via the branched flow path 130". This cycle of operation is then repeated. It will be understood that the control device is configured to adjust the flow rate through the heat exchangers 114 and 116 so that a pre-determined amount of heat is transferred to or from the first coolant to optimise the heat transfer and thereby minimise the amount of energy expended by the cooling apparatus 140 required to cool the first coolant for sufficient cooling of the auxiliary system 30.

The control device is configured to perform this optimisation by taking account of the temperature of the first coolant at the temperature sensors 162, 166, 168.

The fuel cell system 100 may, in examples, permit a smaller sized and/or less energy consuming cooling apparatus 140 to be used due to cooling of the first coolant at the third heat exchanger 114.

In examples, the fuel cell system 100 may not include the cooling apparatus 140 and the third heat exchanger 114 may provide cooling of the first coolant to control the temperature across the fuel cell 29 and/or the auxiliary system 30.

With reference to figure 8, according to another aspect of the present disclosure, a fuel cell system 1000 for the marine vehicle 10 including fuel cell 29 and a coolant circuit connected to the fuel cell 29 is provided. The fuel cell system 1000 has similarities to the fuel cell system 100 but differs in that there is no fuel heat exchanger 110 for pre-heating the fuel using coolant that has been warmed by cooling the fuel cell 29.

The fuel cell system 1000 has a coolant circuit including a first heat exchanger 1112, a second heat exchanger 1114, and a cooling apparatus 1140. The first heat exchanger 1112 includes a first input 1112a for receiving the first coolant, a first output 1112b for said first coolant and a first coolant flow path therebetween. The first heat exchanger 1112 may also be referred to as a fuel cell heat exchanger 1112. The first heat exchanger 1112 is in thermal contact with the fuel cell 29 so that heat is transferred from the fuel cell 29 to the first coolant flow path. The first heat exchanger 1112 may be the same or share features in common with the heat exchanger 112 of the fuel cell system 100. The second heat exchanger 1114 includes a first input 1114a for receiving first coolant, a first output 1114b for said first coolant and a first coolant flow path therebetween. During use of the marine vehicle 10, the second heat exchanger 1114 is in thermal contact with a part of the marine vehicle 10 that is submerged in water so that heat from the first coolant passing through the first coolant flow path is transferred to the water. The second heat exchanger 1114 may the same or share features in common with the heat exchanger 114 of the fuel cell system 100 and may also be referred to as a cooler 1114. The cooling apparatus 1140 has a first input 1140a for receiving the first coolant, a first output 1140b for the first coolant and a first coolant flow path therebetween. The cooling apparatus 1140 may be the same or share features in common with the cooling apparatus 140 of the fuel cell system 100. The system 1000 is arranged such that the first output 1112b of the first heat exchanger 1112 is connected to the first input 1114a of the second heat exchanger 1114, the first output 1114b of the second heat exchanger 1114 is connected to the first input 1140a of the cooling apparatus 1140 and the first output 1140b of the cooling apparatus 1140 is connected to the first input 1112a of the first heat exchanger 1112. According to this example aspect, advantageously, the second heat exchanger 1114 cools the first coolant after it has been warmed by passing through the first heat exchanger 1112 when the fuel cell 29 is on and thus reduces the amount of cooling that must be performed by the cooling apparatus 1140 before the first coolant returns to the first heat exchanger 1112. Depending on the temperature of the water, the cooling apparatus 1140 may not have to perform any additional cooling if the second heat exchanger 1114 can sufficiently cool the first coolant.

In examples, the first heat exchanger 1112 may include a second input for receiving a second coolant, a second output for said second coolant and a second coolant flow path therebetween which input! output are connected to a corresponding output! input of the fuel cell 29 similar to the fuel cell system 100 to provide a closed circuit of the second coolant to transfer heat from the second coolant to the first coolant passing through the first heat exchanger 1112.

In examples the coolant circuit may be arranged to also cool auxiliary system 30. In such examples, the coolant circuit includes a third heat exchanger 1116 including a first input 1116a for receiving the first coolant, a first output 1116b for said first coolant, and a first coolant flow path therebetween and a branched flow path 1130 in between cooling apparatus 1140 and the first heat exchanger 1112 connected to the first input 1116a of the third heat exchanger 1116. The third heat exchanger 1116 may also be referred to as an auxiliary systems heat exchanger 1116. The third heat exchanger 1116 is in thermal contact with the auxiliary system 30 of the marine vehicle 10 during use so that heat is transferred from the auxiliary system 30 to the first coolant passing through the first coolant flow path of the third heat exchanger 1116, and the first output 1116b of the third heat exchanger is connected to the first input 1114a of the second heat exchanger 1114. The third heat exchanger 1116 and branched flow path 1130 are the same as the fourth heat exchanger 116 and flow path 130 of the fuel cell system 100. In examples, similar to the fuel cell system 100 and heat exchanger 116, the third heat exchanger 1116 may include a second input for receiving a third coolant, a second output for said third coolant and a third coolant flow path therebetween; which input / output are connected to a corresponding output / input of the auxiliary system 30 to provide a closed circuit of the third coolant for transfer of heat from the third coolant to the first coolant passing through the third heat exchanger 1116.

In examples, similar to the fuel cell system 100, the fuel cell system 1000 may include a first valve 1150 positioned between the cooling apparatus 1140 and the first heat exchanger 1112.

The first valve 1150 has an input 1150a connected to the output 1140b of the cooling apparatus 1140, a first output 1150b connected to the first input 1112a of the first heat exchanger 1112 and a second output 1150b' connected to the branched flow path 1130 upstream of the third heat exchanger 1116, and the first valve 1150 may be operated to direct the first coolant to one or both of the first heat exchanger 1112 and the third heat exchanger 1116.

The fuel cell system 1000 may have a control device similar to the fuel cell system 1000 and one or more temperature sensors 1162, 1166, 1168 that are in the same relative positions and which have the same purpose of the corresponding sensors 1162, 1166, 1168 of the fuel cell system 100. It will be readily appreciated that the control device may use the temperature signals provided by these temperature sensors to control the operation of the fuel cell system 1000 to optimise its operation in a similar way to that described in relation to the fuel cell system 100 to cool the fuel cell 29 and/or auxiliary system 30. When the fuel cell is turned on, the control device may place the coolant circuit into a first configuration for which the first coolant flows through the first, second and third heat exchangers to cool the fuel cell 29 and auxiliary system 30 with the cooling apparatus turned on or off depending on the temperature of the first coolant outputted by the first output 1140b of the cooling apparatus 1140. When the fuel cell is turned off, the control device may place the coolant circuit into a second configuration for which the first coolant flows through the second and third heat exchangers 1114, 1116 to cool the auxiliary system 30 and not the fuel cell 29, optionally with the cooling apparatus 1140 being turned on or off depending on the temperature of the first coolant outputted by the first output 1140b of the cooling apparatus 1140.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The invention may also broadly consist in the parts, elements, steps, examples and/or features referred to or indicated in the specification individually or collectively in any and all combinations of two or more said parts, elements, steps, examples and/or features. In particular, one or more features in any of the embodiments described herein may be combined with one or more features from any other embodiment(s) described herein.

Protection may be sought for any features disclosed in any one or more published documents is referenced herein in combination with the present disclosure.

Although certain example embodiments of the invention have been described, the scope of the appended claims is not intended to be limited solely to these embodiments. The claims are to be construed literally, purposively, and/or to encompass equivalents.

Any system feature as described herein may also be provided as a method feature, and vice versa. As used herein, means plus function features may be expressed alternatively in terms of their corresponding structure.

Any feature in one aspect may be applied to other aspects, in any appropriate combination. In particular, method aspects may be applied to system aspects, and vice versa. Furthermore, any, some and/or all features in one aspect can be applied to any, some and/or all features in any other aspect, in any appropriate combination.

It should also be appreciated that particular combinations of the various features described and defined in any aspects can be implemented and/or supplied and/or used independently.

Claims

A fuel cell system (100) for a marine vehicle (10) including: a fuel cell (29); a coolant circuit including: a first heat exchanger (110); a second heat exchanger (112); and a third heat exchanger (114), wherein the first heat exchanger (110) includes: a first input (110a) for receiving a fuel, a first output (110b) for said fuel and a fuel flow path therebetween; and a second input (110a') for receiving a first coolant, a second output (110b') for said first coolant and a first coolant flow path therebetween; wherein the first heat exchanger (110) is configured to transfer heat from the first coolant passing through the first coolant flow path to the fuel passing through the fuel flow path during use; wherein the second heat exchanger (112) includes: a first input (112a) for receiving the first coolant, a first output (112b) for said first coolant and a first coolant flow path therebetween; and wherein the second heat exchanger (112) is in thermal contact with the fuel cell (29) so that heat is transferred from the fuel cell (29) to the first coolant passing through the first coolant flow path of the second heat exchanger (112) during use; wherein the third heat exchanger (114) includes: a first input (114a) for receiving first coolant, a first output (114b) for said first coolant and a first coolant flow path therebetween; and wherein, during use of the marine vehicle (10), the third heat exchanger (114) is in thermal contact with a part of the marine vehicle (10) that is submerged in water so that heat from the first coolant passing through the first coolant flow path is transferred to the water; wherein the system is arranged such that: the first output of the first heat exchanger (110b) is connected to the fuel cell (29) to transfer fuel to the fuel cell (29) during use; the second output of the first heat exchanger (110b') is connected to the first input of the second heat exchanger (112a); S the first output of the second heat exchanger (112b) is connected to the first input of the third heat exchanger (114a); and the first output of the third heat exchanger (114b) is connected to the second input of the first heat exchanger (110a').lo 2. A fuel cell system (100) according to claim 1 including: wherein the second heat exchanger (112) has a second input (112a') for receiving a second coolant, a second output (112b') for said second coolant and a second coolant flow path therebetween; wherein the fuel cell (29) includes: a first input (29a) connected to the second output of the second heat exchanger (112b') for receiving the second coolant therefrom; a first output (29b) connected to the second input of the second heat exchanger (112a') for the second coolant to be received by the second heat exchanger (112); and a second coolant flow path therebetween so that heat is transferred from the fuel cell (29) to the second coolant passing through the second coolant flow path of the fuel cell (29) during use, wherein the second heat exchanger (112) is configured to transfer heat from the second coolant passing through the second coolant flow path of the second heat exchanger (112) to the first coolant passing through the first coolant flow path of the second heat exchanger (112).
3. A fuel cell system (100) according to claim 1 or 2, wherein the coolant circuit includes: a fourth heat exchanger (116) including a first input (116a) for receiving the first coolant, a first output (116b) for said first coolant, and a first coolant flow path therebetween; and a branched flow path (130) in between the first heat exchanger (110) and the second heat exchanger (112) connected to the first input of the fourth heat exchanger (116a), wherein the fourth heat exchanger (116) is in thermal contact with an auxiliary system (30) of the marine vehicle (10) during use so that heat is transferred from the auxiliary system (30) to the first coolant passing through the first coolant flow path of the fourth heat exchanger (116), and the first output of the fourth heat exchanger (116b) is connected to the first input of the third heat exchanger (114a).
4. A fuel cell system (100) according to claim 3, wherein the fourth heat exchanger (116) has a second input (116a') for receiving a third coolant, a second output (116b') for said third coolant and a third coolant flow path therebetween; wherein the auxiliary system (30) includes: a first input (30a) connected to the second output of the fourth heat exchanger (116b') for receiving the third coolant therefrom; a first output (30b) connected to the second input of the fourth heat exchanger (116a') for the third coolant to be received by the fourth heat exchanger (116); and a third coolant flow path therebetween so that heat is transferred from the auxiliary system (30) to the third coolant passing through the third coolant flow path of the auxiliary system (30) during use; wherein the fourth heat exchanger (116) is configured to transfer heat from the third coolant passing through the third coolant flow path of the fourth heat exchanger (116) to the first coolant passing through the first coolant flow path of the fourth heat exchanger (116).
5. A fuel cell system (100) according to any preceding claim including a cooling apparatus (140) for cooling the first coolant; wherein the cooling apparatus (140) includes: an input (140a) connected to the second output of the first heat exchanger (110b') to receive the first coolant therefrom during use; and an output (140b) connected to the first input of the second heat exchanger (112a) to permit the cooled first coolant to be sent thereto during use.
6. A fuel cell system (100) according to claim 5 when directly or indirectly dependent on claim 3 wherein the cooling apparatus (140) is positioned in between the first heat exchanger (110) and the branched flow path (130") so that the output of the cooling apparatus (140b) is connected to the first input of the fourth heat exchanger (116a) to permit cooled first coolant to be sent thereto during use.
7. A fuel cell system (100) according to any preceding claim wherein the cooling circuit includes: one or more valves (150, 160, 170) to permit one or more configurations of the cooling circuit, wherein, for each configuration the first coolant flows along a respective path through one or more of the first, second, third and, optionally fourth, heat exchangers; and/or one or more temperature sensors (161, 162, 164, 166, 168, 169) for measuring the temperature of the first coolant at respective positions of the cooling circuit; and a control device for controlling the fuel cell system (100); wherein the control device is configured to control the one or more valves to place the cooling circuit into one of the one or more configurations of the cooling circuit, and/or change the flow rate of the first coolant through one or more of the first, second, third and fourth heat exchangers.
8. A fuel cell system (100) according to claim 7 wherein the control device is configured to receive temperature signal(s) from the one or more temperature sensors (161, 162, 164, 166, 168, 169) and the control device is configured to change the configuration of the cooling circuit and/or flow rate based on the received temperature signal(s).
9. A fuel cell system (100) according to claim 7 or 8 wherein the one or more configurations include a first configuration, for when the fuel cell (29) is on, in which the first coolant passes through the first, second, and third heat exchangers, and the flow rate of the first coolant through the third heat exchanger (114) is adjusted based on the temperature of the water to change the amount of heat transfer from the first coolant passing through the third heat exchanger (114).
10. A fuel cell system (100) according to claim 9 when directly or indirectly dependent on claim 5, wherein the first configuration includes the first coolant passing through the fourth heat exchanger (116).
11. A fuel cell system (100) according to claim 10 wherein the one or more configurations include a second configuration in which the first coolant only passes through the third heat exchanger (114) and the fourth heat exchanger (116), and the control device is configured to place the coolant circuit into the second configuration when the fuel cell (29) is off.
12. A fuel cell system (100) according to any one of claims 9 to 11 when directly or indirectly dependent on claim 5 wherein the first configuration includes the first coolant passing through the cooling apparatus (140), and when the coolant circuit is in the first configuration, the control device is configured so that if the control device determines that the temperature of the first coolant at the second output of the first heat exchanger (110b') is below or at a pre-determined temperature, the fuel cell system (100) is operated with the cooling apparatus off, and if the control device determines that the temperature is above the pre-determined temperature, the fuel cell system (100) is operated with the cooling apparatus on.
13. A fuel cell system (100) according to any one of claims 11 to 12 when directly or indirectly dependent on claim 5 wherein the second configuration includes the first coolant passing through the cooling apparatus (140), and wherein the control device is configured so that, when the coolant circuit is in the second configuration, if the control device determines that the temperature of the first coolant at the output of the third heat exchanger (114b) is below or at a predetermined temperature, the fuel cell system (100) is operated with the cooling apparatus (140) off, and if the control device determines that the temperature is above the pre-determined temperature, the fuel cell system (100) is operated with the cooling apparatus (140) on.
14. A fuel cell system (100) according to any one of claims 7 to 13 wherein the control device is configured to adjust the flow rate of the first coolant through the first, second, third and/or fourth heat exchanger so that a pre-determined amount of heat is transferred to or from the first coolant at the respective first, second, third and/or fourth heat exchanger.
15. A fuel cell system (100) according to claim 14 wherein the control device is configured to optimise the amount of heat transfer so that the amount of energy expended by the cooling apparatus required to cool the first coolant is minimised.
16. A fuel cell system (100) according to any one of claims 7 to 15 when directly or indirectly dependent on claim 3, wherein the cooling circuit includes a first valve (150) positioned between the first heat exchanger (110) and the second heat exchanger (112), the first valve (150) including: an input (150a) for receiving the first coolant flowing downstream of the second output of the first heat exchanger (110b'), a first output (150b) for said first coolant and a second output (150b') for said first coolant, wherein the system is arranged such that: the input of the first valve (150a) is connected to the second output of the first heat exchanger (110b'); the first output of the first valve (150b) is connected to the first input of the second heat exchanger (112a); the second output of the first valve (150b') is connected to the first input of the fourth heat exchanger (116a) by the branched flow path (130") extending therebetween, wherein the first valve (150) is controlled by the control device to permit the first coolant to flow to one or both of the second and fourth exchangers.
17. A fuel cell system (100) according to claim 16 when directly or indirectly dependent on claim 5 wherein the input of the first valve (150a) is connected to the output of the cooling apparatus (140b) to receive cooled first coolant therefrom during use.
18. A fuel cell system (100) according to claim 16 or 17, wherein the cooling circuit includes a second valve (160) positioned between the first heat exchanger (110) and the first valve (150), wherein the second valve (160) includes an first input (160a) for receiving the first coolant, a second input (160a') for receiving the first coolant and an output (160b) for said first coolant; and a branched flow path (130") downstream of the third heat exchanger (114) and upstream of the second inlet of the first heat exchanger (110a'), wherein the system is arranged such that: the first input of the second valve (160a) is connected to the outlet of the third heat exchanger (114b) to received cooled first coolant therefrom; the second input of the second valve (160a') is connected to the second output of the first heat exchanger (110b') to receive cooled first coolant therefrom; and the output of the second valve (160b) is connected to the input of the first valve (150a), wherein the second valve (160) is controlled by the control device so that the first coolant flows from only one of the first input (160a) or the second input (160a') to the first valve (150).
19 A fuel cell system (100) according to claim 18 when directly or indirectly dependent on claim 5 wherein the cooling apparatus (140) is positioned in between the second valve (160) and the first valve (150) so that the output of the second valve (160b) is connected to the first input of the cooling apparatus (140a) and the first output of the cooling apparatus (140b) is connected to the input of the second valve (160a) to receive cooled therefrom during use.
20. A fuel cell system (100) according to claim 18 or 19 including: a third valve (170) including an input (170a) for receiving the first coolant, a first output (170b) for said first coolant and a second output (170b') for said first coolant, wherein the system is arranged such that: the input of the third valve (170a) is connected to the first outlet of the third heat exchanger (114b) to receive coolant first coolant therefrom; the first output of the third valve (170b) is connected to the second input of the first heat exchanger (110a'); the second output of the third valve (170b') is connected to the input of the first valve (150a), wherein the third valve (170) is controlled by the control device so that the first coolant flows only from one of the first and second outputs of the third valve (170).
21 A fuel cell system (100) according to any one of claims 7 to 20, wherein the cooling circuit includes a first temperature sensor (161) positioned downstream of the first output of the second heat exchanger (112b) and upstream of the third heat exchanger (114) to measure the temperature of the first coolant outputted at the first output of the second heat exchanger (112b).
22 A fuel cell system (100) according to any one of claims 7 to 21, wherein the cooling circuit includes a second temperature sensor (162) positioned downstream of the first output of the third heat exchanger (114b) and upstream of the first heat exchanger (110) to measure the temperature of the cooled first coolant outputted at the first output of the third heat exchanger (114b).
23 A fuel cell system (100) according to any one of claims 7 to 22, wherein the cooling circuit includes a third temperature sensor (164) positioned downstream of the second output of the first heat exchanger and upstream of the second heat exchanger to measure the temperature of the cooled first coolant outputted at the second output of the first heat exchanger.
24. A fuel cell system (100) according to any one of claims 7 to 23, wherein the cooling circuit includes a fourth temperature sensor (166) positioned for measuring the temperature of the water outside the marine vehicle during use, and wherein the control device is configured to adjust the flow rate of the first coolant through the third heat exchanger (114) based on the temperature.
25 A fuel cell system (100) according to any preceding claim wherein the third heat exchanger (114) includes: one or more tubes along which the first coolant flows during use and are arranged so that, in use, the one or more tubes are in thermal contact with the surface of the marine vehicle (10) that is in contact with the water so that heat is transferred from the first coolant to the water.
26 A fuel cell system (100, 1000) for a marine vehicle (10) including: a fuel cell (29); a coolant circuit connected to the fuel cell (29), and the coolant circuit including: a first heat exchanger (1112); a second heat exchanger (1114), a cooling apparatus; wherein the first heat exchanger (1112) includes: a first input (1112a) for receiving the first coolant, a first output (1112b) for said first coolant and a first coolant flow path therebetween, wherein the first heat exchanger (1112) is in thermal contact with the fuel cell (29) so that heat is transferred from the fuel cell (29) to the first coolant flow path, and wherein the second heat exchanger (1114) includes: a first input (1114a) for receiving first coolant, a first output (1114b) for said first coolant and a first coolant flow path therebetween; and wherein, during use of the marine vehicle (10), the second heat exchanger (1114) is in thermal contact with a part of the marine vehicle (10) that is submerged in water so that heat from the first coolant passing through the first coolant flow path is transferred to the water; wherein the cooling apparatus (1140) has a first input (1140a) for receiving the first coolant, a first output (1140b) for the first coolant and a first coolant flow path therebetween; wherein the system is arranged such that: the first output of the first heat exchanger (1112b) is connected to the first input of the second heat exchanger (1114a); the first output of the second heat exchanger (1114b) is connected to the first input of the cooling apparatus (1140a); and the first output of the cooling apparatus (1140b) is connected to the first input of the first heat exchanger (1112a).
27 A fuel cell system (100, 1000) according to claim 26 including: a second coolant; wherein the first heat exchanger (1112) has a second input for receiving the second coolant, a second output for said second coolant and a second coolant flow path therebetween; wherein the fuel cell (29) has a first input for receiving the second coolant, a first output for said second coolant and a second coolant flow path therebetween so that heat is transferred from the fuel cell (29) to the second coolant flow path; wherein the first heat exchanger (1112) is configured to transfer heat from the second coolant passing through the second coolant flow path to the first coolant passing through the first coolant flow path; wherein the system is arranged such that: the second output of the first heat exchanger is connected to the first input of the fuel cell (29); and the first output of the fuel cell (29) is connected to the second input of the first heat exchanger.
28 A fuel cell system (100, 1000) according to claim 26 or 27, wherein the coolant circuit includes: a third heat exchanger (1116) including a first input (1116a) for receiving the first coolant, a first output (1116b) for said first coolant, and a first coolant flow path therebetween; and a branched flow path (1130) in between cooling apparatus (1140) and the first heat exchanger (1112) connected to the first input of the third heat exchanger (1116a), wherein the third heat exchanger (1116) is in thermal contact with an auxiliary system (30) of the marine vehicle (10) during use so that heat is transferred from the auxiliary system (30) to the first coolant passing through the first coolant flow path of the third heat exchanger (1116), and the first output of the third heat exchanger (1116b) is connected to the first input of the second heat exchanger (1114a).
29. A fuel cell system (100, 1000) according to claim 28 wherein the coolant circuit includes a first valve (1150) positioned between the cooling apparatus (1140) and the first heat exchanger (1112), wherein the first valve (1150) has an input (1150a) connected to the output of the cooling apparatus (1140b), a first output (1150b) connected to the first input of the first heat exchanger (1112a) and a second output (1150a') connected to the branched flow path (1130) upstream of the third heat exchanger (1116), and wherein the first valve (1150) may be operated to for direct the first coolant one or both of the first heat exchanger and the third heat exchanger.
30. A fuel cell system (100, 1000) according to claim 29 including: wherein the third heat exchanger (1116) has a second input for receiving a third coolant, a second output for said third coolant and a third coolant flow path therebetween; wherein the auxiliary system (30) includes: a first input connected to the second output of the third heat exchanger for receiving the third coolant therefrom; a first output connected to the second input of the third heat exchanger for the third coolant to be received by the third heat exchanger (1116); and a third coolant flow path therebetween so that heat is transferred from the auxiliary system (30) to the third coolant passing through the third coolant flow path of the auxiliary system (30) during use; wherein the third heat exchanger (1116) is configured to transfer heat from the third coolant passing through the third coolant flow path of the fourth heat exchanger to the first coolant passing through the first coolant flow path of the fourth heat exchanger.
31 A fuel cell system (100, 1000) according to any preceding claim wherein the first coolant and second coolants are different coolants, and optionally or preferably the second and third coolants are the same coolant, or the first, second and third coolants are different coolants.
32. A fuel cell system (100, 1000) according to any preceding claim wherein the fuel is hydrogen.
33. A fuel cell system (100, 1000) according to any preceding claim including wherein the fuel is stored at cryogenic temperatures.
34 A fuel cell system (100, 1000) according to any preceding claim including: a fuel tank (21a, 21b); and a heating element for heating the fuel.A marine vehicle (10) including a fuel cell system (100, 1000) according to any preceding claim, optionally or preferably the marine vehicle (10) including a or the auxiliary system (30).