Hydrogen has a wide range of sources and no pollution of combustion products. It is expected to become one of the main energy carriers in the future.At present, hydrogen fuel cell vehicles have been commercialized, but a considerable number of hydrogenation stations are needed for further promotion.In 2020, China Society of automotive engineering issued the construction goal of China’s hydrogen refueling stations. From 2025 to 2030, the number of hydrogen refueling stations will increase from 1000 and 5000.By the end of 2020, 118 have been built in China, but hydrogen energy vehicles are still in its infancy.
At present, the hydrogenation station is mainly externally supplied, and the filling system generally consists of: hydrogen supply source, compressor, station side storage tank (high-pressure storage tank, medium pressure storage tank, etc.), pressure reducing valve, precooling and hydrogenation machine.Generally, the long tube trailer transports the hydrogen of about 20MPa to the hydrogenation station and pressurizes and fills it into the in-car automotive gas cylinder or high-pressure storage tank through the compressor. The compression process is generally a constant entropy process, which will increase the temperature of hydrogen. Under the rated pressure of limited space, the amount of stored hydrogen will be greatly reduced, so it must be cooled in the hydrogenation process.The cooling system will be one of the main costs of the operation cost of the later hydrogenation station. In Germany, the cooling cost of hydrogenation station exceeds 10kwh / kg H2. If the utilization rate of hydrogenation station is low, the cooling cost will be greatly increased.
In order to reduce the operation energy consumption of the cooling system, the carrier cooling system is generally used. The carrier cooling system can ensure the stability of hydrogenation process, reduce the starting frequency of refrigeration equipment and improve the cop of refrigeration system.
At present, the traditional coolant is mainly calcium chloride brine and ethylene glycol aqueous solution, but the service temperature of the hydrogenation station is low, which can generally be as low as – 40 ℃. The viscosity of ethylene glycol aqueous solution is too large to be used, and most choose calcium chloride aqueous solution.However, calcium chloride aqueous solution is particularly corrosive to the system. Generally, the equipment needs to be replaced in 3-5 years, which increases the fixed cost.At present, there are successful application cases of glacier coolant in hydrogenation station. It has high thermal conductivity, high specific heat, low viscosity and non corrosivity, and can be highly suitable for the cooling system of hydrogenation station.