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1) Energy saving, high conversion efficiency, no need for petroleum fuel
a) In addition to the use of gasoline reforming to produce hydrogen, other (methanol, hydrocarbon, etc.) fuels are essentially free of petroleum fuel.
The overall efficiency of the engine from the drive system to the wheels is about 11% for internal combustion engines. The actual efficiency of FCEV with hydrogen as fuel reaches 50% to 70%; with methanol as fuel, after reforming, hydrogen FCEV is produced, and the actual efficiency reaches 34%. It can be seen that the actual efficiency of FCEV is much higher than that of internal combustion engines.
b) The internal combustion engine has ** efficiency near the rated power, while operating under partial power output conditions, the efficiency is rapidly reduced.
The efficiency of the fuel cell at rated power can reach 60%, while the operating efficiency can reach 70% under partial power output conditions, and the operating efficiency can reach 50-55% under overload power output conditions. The high efficiency varies widely with power, and the high operating rate at low power is particularly suitable for automotive power performance requirements.
c) The internal combustion engine has low overload capacity and is easy to "extinguish" during overload operation.
The short-time overload capability of the fuel cell can reach 200% of the rated power, which is very suitable for the characteristics of the car's dynamic performance during acceleration and climbing.
In summary, fuel cells are far more energy efficient than internal combustion engines, and have higher stability and reliability than internal combustion engines.
2) Emissions reach zero pollution of harmful gases in the exhaust gas of internal combustion engines. The pollution caused by the environment is a fatal shortcoming of internal combustion engine vehicles. Although various technical measures inside and outside the aircraft have been adopted, only low pollution can be achieved. "The level, due to the large number of internal combustion engine vehicles, even "low pollution" has a huge impact on the global environment. The fuel cell engine that uses hydrogen as a fuel mainly produces water as "zero pollution." The fuel cell engine fueled with hydrocarbons is mainly composed of water, carbon dioxide and carbon monoxide, and is classified as "ultra-low pollution". Fuel cell engines are an ideal power device because of the requirements for global environmental protection and the pursuit of new energy sources, and it is possible to gradually replace petroleum as the main energy source for vehicles.
3) Vehicle performance is close to the internal combustion engine. The specific power of the internal combustion engine is about 300W/kg. At present, the specific power of the fuel cell body is 700 W/kg and the power density is 1000W/L. If the fuel cell reformer, purifier and accessory are included, the specific power is 300-350 W/kg and the power density is 280 W/L. In terms of energy, the fuel cell is close to the internal combustion engine, so its power performance can reach the level of the internal combustion engine.
4) Simple structure and stable operation
a) The energy conversion of the fuel cell engine is done under static conditions, and the structural components are simple in construction. Machining accuracy requirements are much lower than for internal combustion engines. In particular, the proton exchange membrane fuel cell has high energy conversion efficiency and can be started and operated at a low temperature of 80 ° C, and the heat resistance of the structural member is not high. Most of the structural parts are plate-shaped and pipe-shaped, there are no moving parts and various friction pairs, and there is no failure caused by wear of parts, and maintenance and maintenance are convenient.
b) The fuel cell engine consists of a series of individual fuel cells connected in series and can be configured into a series of fuel cell engine modules of various specifications, which can be assembled in different applications and different types of vehicles. In the vehicle, the specific arrangement of the effective space of the vehicle can be allocated according to the axle load of the vehicle, and the overall arrangement can be performed flexibly and maneuverably.
c) During the operation of the fuel cell engine, the noise is small, the vibration is small, the heat dissipation system is much simpler than the internal combustion engine, and the thermal management system is simpler; the output does not need to be cleaned and silenced, and the entire fuel cell system is easily automated. System Management.
Second, the shortcomings of fuel cells
1) Single fuel type Currently, whether it is liquid hydrogen, gaseous hydrogen, hydrogen stored in hydrogen storage metal, and hydrogen converted by reforming carbohydrates, it is the fuel of fuel cells. Hydrogen generation, storage, storage, transportation, and filling or reforming are complex and require high safety. However, the singularity of fuel types can establish a standardized and unified supply system.
2) A single cell requiring a high quality sealed fuel cell can generate a voltage of about 1 V. The voltage of a single cell of a different type of fuel cell can be slightly different. Usually, a plurality of single cells are combined into a fuel cell engine group according to the requirements of voltage and current use. When combining, the electrodes between the cells must be tightly sealed, because the poorly sealed fuel cell, hydrogen gas Leaking out of the fuel cell reduces the utilization of hydrogen and seriously affects the efficiency of the fuel cell engine, and also causes hydrogen combustion accidents. Due to the demanding strict sealing, the manufacturing process of the fuel cell engine is complicated and brings many difficulties to use and maintenance.
3) The specific power of the internal combustion engine is further increased by about 300 W/kg, and the specific power of the hydrogen-fueled fuel cell is about 300-350 W/kg, and the power density is 280 W/L. The integrated power density (including the reformer mass) of the fuel-fueled fuel cell produced by the reforming of methanol is reduced to 220 W/L. In order to meet the requirements of the FCEV power performance, it is necessary to further increase the specific power of the fuel cell engine.
4) The cost is too high. Proton exchange membrane fuel cells are one of the most promising fuel cells. However, proton exchange membrane fuel cells require platinum (Pt) as a catalyst, and the dosage is 0.1-0.2 mg/cm3. The current dosage requirement is 0.5mg/cm3, which is far from the requirement. Moreover, platinum (Pt) will be "poisoned" by the action of CO during the reaction. The use of platinum (Pt) and the failure of platinum (Pt) have kept the cost of proton exchange membrane fuel cells high.
5) An auxiliary battery system is required. The fuel cell can continuously generate electricity, but cannot charge and recover the feedback energy of the FCEV regenerative braking. An auxiliary battery is usually added to the FCEV to store the rich energy of the fuel cell and the energy when the FCEV is subjected to regenerative braking when decelerating.
Advantages and disadvantages of automotive fuel cell engines
First, the advantages of fuel cells