1. Classification of fuel cell vehicles
1) Classification by fuel type
According to whether the fuel can be used directly, fuel cell vehicles can be divided into the following two categories.
(1) Direct fuel cell vehicles; directly use hydrogen, gas, natural gas, etc. as fuel.
(2) Reforming fuel cell vehicles: gasoline, methanol and other fuels are processed by reforming technology as fuel.
2) Classification by hydrogen fuel storage method
According to the storage method of hydrogen fuel, fuel cell vehicles can be divided into the following three categories.
(1) Compressed hydrogen fuel cell vehicles: use hydrogen stored in high-pressure tanks as fuel.
(2) Liquid hydrogen fuel cell vehicle: the liquid hydrogen stored in the high-pressure tank is vaporized as fuel.
(3) Alloy adsorption hydrogen fuel cell vehicle: hydrogen adsorbed in the alloy block is used as fuel.
3) Classification by “multiple power supply” configuration
According to the “multi-power” configuration, fuel cell vehicles can be divided into the following four categories.
(1) Pure fuel cell (PFC) fuel cell vehicles
(2) Fuel cell and battery combined drive (fuel cell+battery, FC+B) fuel cell vehicle.
(3) Fuel cell and super capacitor combined drive (fuel cell + capacitor, FC + C) fuel cell vehicle.
(4) Combined drive of fuel cell, battery and super capacitor (fuel cell +battery+capacitor, FC+B+C)
fuel cell vehicle.
2. Characteristics of fuel cell vehicles
1) Advantages of fuel cell vehicles
(1) High efficiency.
The working process of a fuel cell is a process of converting the chemical energy in the fuel into usable electrical energy through an electrochemical reaction. It is not limited by the Carnot cycle, and there is no energy conversion in the form of mechanical motion, so the energy conversion efficiency of fuel cells is high, which is 2-3 times that of diesel engines and gasoline engines.
(2) Long driving mileage.
Using the fuel cell system as the energy source overcomes the shortcoming of the poor driving ability of the new energy electric vehicle. Its driving ability has almost reached the driving ability of traditional cars.
(3) Green and environmental protection.
There is no combustion link in the working process of the fuel cell, using hydrogen, methane, etc. as fuel, and the products are mainly water, carbon monoxide and carbon dioxide, which belong to “ultra-low pollution”.
(4) Strong overload capacity.
In addition to the high working efficiency in a wide working range, the fuel cell has a short-term overload capacity of up to 200%, which is very suitable for the characteristics of the vehicle’s dynamic performance during acceleration and climbing.
(5) No vibration and noise, long life.
This characteristic is mainly related to its working characteristics. It reacts on the two electrodes through the fuel and the catalyst respectively, and the closed circuit is formed by the electrolyte and the outer circuit. Therefore, there is no mechanical vibration and noise during the working process, thereby reducing the wear of mechanical components and prolonging the service life.
(6) Simple structure and stable operation.
The energy conversion of the fuel cell is completed in a static state, the structure is relatively simple, and the processing precision of the components is relatively low. In particular, the proton exchange membrane fuel cell has high energy conversion efficiency, can work under low temperature conditions, and has low requirements on the heat resistance of components. Because there is no mechanical vibration, the fuel cell vehicle runs relatively smoothly.
2) Disadvantages of fuel cell vehicles
(1) The starting time is long.
The starting time of a fuel cell vehicle using hydrogen as fuel generally takes several minutes; the starting time of a fuel cell vehicle using methanol or gasoline reforming technology is longer, which is much longer than that of a vehicle with a transmission internal combustion engine, which affects the mobility of the vehicle.
(2) High cost.
Fuel cell vehicles are still in the experimental stage and cannot be mass-produced, which makes the manufacturing cost of fuel cell vehicles high. Gas stations and maintenance technology are not widely available, which also makes fuel cell vehicles more expensive to use and maintain.
(3) The volume and mass are large.
Since fuel cells can only generate electricity and cannot store electrical energy, fuel cell vehicles need to be equipped with batteries to store electrical energy. The configuration of batteries and auxiliary equipment increases the volume and mass of fuel cell vehicles.
(4) The infrastructure of hydrogen refueling stations is not perfect.
The construction investment of fuel cell vehicle fuel supply station is large, and the system has not yet been formed, which cannot provide guarantee for long-term continuous driving, which is an important factor affecting the development of fuel cell vehicle.