The evaluation of fuel cell performance, in addition to working life, weight, cost, etc., the most important is efficiency. In general, the efficiency of the energy conversion device means the percent ratio of energy output by the device, that is, output energy / luminos energy X 100%Except for electrical energy conversion devices. Other energy conversion devices are converted to mechanical energy or thermal energy, and then converted into electrical energy. The efficiency is limited by the energy conversion process. However, the fuel cell does not have such a constraint, and its efficiency is higher than the efficiency of other energy conversion devices.
However, the efficiency expression of the fuel cell is also very complex, and generally there are several common efficiency expression methods.
1, thermodynamic efficiency
Thermodynamic efficiency is also known as extreme efficiency, which is the highest efficiency that the fuel cell can achieve. Since the fuel used in the fuel cell can generally be combusted and released energy, the thermodynamic efficiency can be compared with thermal energy (AH) generated by the power generation device, theoretically, the thermodynamic efficiency of the fuel cell is lower than the low temperature when the fuel cell is low. . However, at higher temperatures, the reaction rate increases. And the excessive current density is lower than the low temperature. In addition, the high temperature fuel cell can be used less easily or without a noble metal electrode catalyst. Thus, a comprehensive comparison, the actual efficiency of the high temperature fuel cell is higher.
2, electrochemical efficiency
Electrochemical efficiency, also known as voltage efficiency, for different battery design, even the same electrochemical reaction, there will be different efficiency.
3, power generation efficiency
The power generation efficiency of the fuel cell is also known as the actual efficiency, which affects the actual efficiency, mainly with current density, polarization, temperature, fuel utilization.
4, coputical energy efficiency
A significant advantage of the fuel cell is to provide high quality hot water or water vapor, especially a fuel cell power plant and a power plant above, especially those over a kW. Such power generation modes are called combined heating power generation (CHP, Combined Heat and Power), also known as co-power generation. The total power generation power is equal to the sum of the fuel cell power output power and heat load.
5. For a complete fuel cell system, the entire process of power generation is in addition to power generation and heating, and also includes fuel reforming, reactive gas delivery, electrode heating, cooling, power adjustment, and conversion, etc., the efficiency of these processes affects The total efficiency of the fuel cell system. The total efficiency of fuel cells is the result of all process efficiency.
Measuring the performance of the fuel cell and the fuel cell compares to other power generation devices, some technical indicators or parameters are used, including current density, power density, cost, and efficiency.
(1) Current density. The key indicator of a single fuel cell is the current density, that is, the current intensity (MA / CM2) on the unit electrode area. However, it is to be noted that the current strength of the fuel cell is not proportional to the electrode area, and the electrode area is doubled, and the current intensity does not double. The cause is more complicated. Related to factors such as the type of fuel cell and the design of the battery.
(2) Power density. The fuel cell power supply has a certain power, weight, and volume. Key indicators are power density and specific power.
(3) Life. The life of the fuel cell usually refers to the accumulation time (H) of the power supply. When the fuel cell cannot output a rated power, its life is ended. For example, a rated power 1 kW tender product power supply, the output power at the factory is generally 20% higher than the rated power, namely 1.2 kW. When the output power of the power supply is less than 1 kW, it is invalid. Thousands of hourly voltage drops are also used to make the life of the fuel cell.
(4) Cost. The cost of the fuel cell is the most important indicator of its application, represented by USD / KW.
(5) Efficiency. Like other power generation devices, efficiency is an important indicator of fuel cell power. Efficiency is closely related to energy utilization, and it is especially important in today's weakness. Recommend: LiFePO4 Battery Manufacturer Energy storage battery Manufacturer Integrated machine energy storage battery series Manufacturer Lead lithium battery Manufacturer Outdoor Backup Battery Manufacturer Portable outdoor power supply Manufacturer Power battery Manufacturer Powerwall LiFePO4 Battery Manufacturer Battery rack Manufacturers Telecom LiFePO4 Battery Manufacturer Wall mounted battery storage Manufacturer China Lifepo4 Battery
