US-12617314-B2 - Heat management system for a fuel cell vehicle

Abstract

A heat management system for a fuel cell vehicle propelled by an electric traction motor includes a fuel cell system comprising a fuel cell configured to generate electric power when receiving hydrogen through a hydrogen inlet and oxygen through an oxygen inlet, wherein the fuel cell includes an outlet configured to expel exhaust water formed in the fuel cell, and a compressor including an inlet configured to receive ambient air, and an outlet, wherein the inlet of the compressor is arranged in downstream fluid communication with the outlet of the fuel cell and configured to pressurize a mixture of exhaust water expelled from the fuel cell and ambient air.

Inventors

• Gordon Ekman
• Roland Kvist

Assignees

• VOLVO CONSTRUCTION EQUIPMENT AB

Dates

Publication Date

20260505

Application Date

20230307

Priority Date

20220314

Claims (13)

1. 1 . A heat management system for a fuel cell vehicle propelled by an electric traction motor, the heat management system comprising: a fuel cell system comprising a fuel cell configured to generate electric power when receiving hydrogen through a hydrogen inlet and oxygen through an oxygen inlet, wherein the fuel cell comprises an outlet configured to expel exhaust water formed in the fuel cell, and a compressor comprising an inlet configured to receive ambient air, and an outlet connected to an ambient environment, wherein the inlet of the compressor is arranged in downstream fluid communication with the outlet of the fuel cell and configured to pressurize a mixture of exhaust water expelled from the fuel cell and ambient air, wherein the pressurized mixture is configured to be directed towards the ambient environment.
2. 2 . The heat management system according to claim 1 , wherein the heat management system further comprises an air heating arrangement arranged in downstream fluid communication with the outlet of the compressor.
3. 3 . The heat management system according to claim 2 , wherein the air heating arrangement is an electrical brake resistor, the electrical brake resistor comprises an electric resistive material connectable to the electric power system.
4. 4 . The heat management system according to claim 1 , wherein the fuel cell system comprises a water tank arranged in fluid communication between the outlet of the fuel cell and the inlet of the compressor.
5. 5 . The heat management system according to claim 1 , wherein the fuel cell system comprises a valve arranged in fluid communication between the outlet of the fuel cell and the inlet of the compressor.
6. 6 . The heat management system according to claim 1 , wherein the heat management system further comprises an electric traction motor configured to propel the vehicle and to controllably regenerate electric power during braking of the vehicle.
7. 7 . The heat management system according to claim 6 , wherein the electric traction motor is electrically connected to an electric power system and configured to receive electric power from the electric power system during propulsion, and to feed electric power to the electric power system during braking.
8. 8 . The heat management system according to claim 6 , wherein the electric power system comprises an energy storage system configured to receive electric power from the electric traction motor during braking.
9. 9 . The heat management system according to claim 8 , wherein the energy storage system is electrically connected to the fuel cell and configured to receive electric power generated by the fuel cell.
10. 10 . The heat management system according to claim 8 , wherein the heat management system further comprises an electric machine electrically connectable to the electric power system of the vehicle, the electric machine being operable by electric power received from the electric power system, and a control unit connected to the electric power system, the control unit comprising control circuitry configured to: determine an electric power absorption capability of the energy storage system, compare the electric power absorption capability with a level of electric power generated by the electric traction motor during braking, and control the electric power system to feed electric power to the electric machine for operating the compressor when the level of electric power generated by the electric traction motor exceeds the electric power absorption capability.
11. 11 . The heat management system according to claim 10 , wherein the control unit is connected to the fuel cell system, the control circuitry being further configured to: control the fuel cell system to feed exhaust water to the inlet of the compressor when the electric power generated by the electric traction motor exceeds the electric power absorption capability.
12. 12 . A method of controlling a heat management system of a fuel cell vehicle, the heat management system comprising a fuel cell system comprising a fuel cell configured to generate electric power when receiving hydrogen through a hydrogen inlet and oxygen through an oxygen inlet, wherein the fuel cell comprises an outlet configured to expel exhaust water formed in the fuel cell, a compressor comprising an inlet configured to receive ambient air and an outlet connected to an ambient environment, wherein the inlet of the compressor is arranged in downstream fluid communication with the outlet of the fuel cell, an electric power system, and an electric traction motor configured to propel the vehicle and to generate electric power during braking, the electric traction motor being electrically connected to the electric power system, wherein the method comprises: determining an electric power absorption capability of an energy storage system of the electric power system, comparing the electric power absorption capability with a level of electric power generated by the electric traction motor during braking, and controlling the compressor to pressurize a mixture of exhaust water expelled from the fuel cell and ambient air when the level of electric power generated by the electric traction motor exceeds the electric power absorption capability, and feed the pressurized mixture towards the ambient environment.
13. 13 . A fuel cell vehicle, comprising a heat management system according to claim 1 .

Description

CROSS REFERENCE TO RELATED APPLICATION This application claims foreign priority to European Application No. 22161874.7 filed on Mar. 14, 2022, the disclosure and content of which is incorporated by reference herein in its entirety. TECHNICAL FIELD The present disclosure relates to a heat management system for a fuel cell vehicle propelled by an electric traction motor. The disclosure also relates to a method of controlling a heat management system. Although the disclosure will mainly be directed to a vehicle in the form of a working machine, the disclosure may also be applicable for other types of vehicles using a fuel cell and an electric traction motor for propulsion, such as e.g. trucks, buses, and other transportation vehicles. BACKGROUND The propulsion systems of vehicles are continuously developed to meet the demands from the market. A particular aspect relates to the emission of environmentally harmful exhaust gas. Therefore, vehicles propelled by electric machines and/or electric machine receiving electric power from hydrogen fuel cells have been increasingly popular, in particular for trucks and other heavy duty vehicles. With reference to a hydrogen fuel cell, this component produces a substantial amount of exhaust water. As an example, 60 liters may be produced per 100 kW and hour. The exhaust water is expelled from the fuel cell as a mix of low temperature steam and condensed water. Since the fuel cell expels a substantial amount of water, this water needs to be taken care of. Should the water be expelled to the ground surface there is a risk of soiling the operating path which can be hazardous. An option is to use a drain tank. However, such drain tank needs to be substantial in size for avoiding the need of emptying the tank too frequently. It is therefore a desire to provide a heat management system for a fuel cell vehicle that is able to efficiently handle the water expelled during operation. SUMMARY It is thus an object of the present disclosure to at least partially overcome the above described deficiencies. According to a first aspect, there is provided a heat management system for a fuel cell vehicle propelled by an electric traction motor, the heat management system comprising a fuel cell system comprising a fuel cell configured to generate electric power when receiving hydrogen through a hydrogen inlet and oxygen through an oxygen inlet, wherein the fuel cell comprises an outlet configured to expel exhaust water formed in the fuel cell, and a compressor comprising an inlet configured to receive ambient air, and an outlet, wherein the inlet of the compressor is arranged in downstream fluid communication with the outlet of the fuel cell and configured to pressurize a mixture of exhaust water expelled from the fuel cell and ambient air. The compressor should thus be construed as a compressor arranged to pressurize gas in gaseous form as well as gas in liquid form, i.e. condensed form. The compressor may be operated in a number of manners. For example, the compressor may be an electric compressor operated by electric power received from e.g. the below described electric power system. As will also be described below, the compressor may be operated by an electric machine. In this example, the compressor is mechanically connected to the electric machine via e.g. a shaft. The electric machine in turn may be operated by electric power received from the electric power system. As a further example, the compressor is a mechanically operated compressor. In such a case, the compressor is connected to a rotating shaft for operation. The rotating shaft may, for example, be a shaft of an electric traction motor propelling the wheels of the vehicle. The compressor may in such case be connected to the shaft via a clutch for controlling operation of the compressor. The present disclosure is based on the insight that a compressor can advantageously be used for transforming the exhaust water from the fuel cell into heated steam. The heated steam can, downstream the compressor, be expelled to the ambient environment through e.g. an exhaust pipe or chimney. The exhausted heated steam is environmentally friendly and will not soil the operating path. An advantage is thus that the heat management system removes the relatively large amount of water expelled from the fuel cell in an efficient and safe way. Moreover, the compressor can also be advantageously used for dissipating excessive electric power when e.g. an energy storage system is unable to receive electric power during, for example, braking using electric traction motor(s) of the vehicle for controlling the vehicle speed. In particular, if the compressor is an electric compressor operated by electric power, the excessive electric power generated during braking can be fed to the compressor. In a similar vein, if the compressor is operated by an electric machine, the excessive electric power generated during braking can be fed to the electric machine, whic