According to thermo-dynamical property, hydrogen desorption pressure of the metal hydride varies with the temperature, which follows the equation:
Here, Pd stands for hydrogen desorption equilibrium pressure, △H0 and △S0 stand for enthalpy change and entropy change of the reaction respectively.
Hydrogen storage alloy absorbs the hydrogen under lower temperature and lower pressure. When increasing the temperature, the metal hydride will release high pressure hydrogen. The metal hydride hydrogen compressor is designed based on this characteristic. And it can be split into two basic types, single-stage compression and multistage compression, according to different requests on thehydrogen pressure and compression ratio. The schematic sketch is shown in Fig. 1:
Take two-stage compression for example, the process of hydrogen compression can be divided into three steps as shown in Fig. 2.
(1) compressorⅠ absorbs hydrogen: hydrogen with certain pressure is pressed into compressorⅠ, meanwhile, low temperature medium is used to cool the compressor circularly.
(2) supercharge the compressorⅠ, while the compressor II absorbs hydrogen: compressorⅠ is heated and supercharged by high temperature medium circularly, and then the hydrogen is released to buffer bottle. Next, compressor II absorbs hydrogen, using low temperature medium to cool compressor II circularly.
(3) supercharge the compressor II: compressor II is heated and supercharged by high temperature medium circularly, and the high-pressure hydrogen is collected into the gas bottle.
Hydrogen discharging capacity
Circulation Medium (Water)
The specification of usual metal hydride hydrogen compressors are listed in the above sheet. We can design the compressor according to the requirement of the customers. The product can be supercharged from standard pressure to 45 MPa, and the hydrogen discharging capacity is various from a few cubic meters per hour to hundreds of cubic meters per hour. We can also customize the hydrogen compressor heated by electricity.
Properties and application
Due to the limits of compression ratio in industrial product, most of the compressors need multistage supercharging to meet the demand of high pressure. So this product has some disadvantages, such as large in size, heavy in weight, and high power consumption. It also reduces hydrogen purity and additional hydrogen purifying equipment is needed. By contrast, our product is small, noiseless, low operating cost, easy to operate and maintain, and can also purify the hydrogen. It is an economic and efficient product, which can replace the traditional mechanical compressors.
The product can be used as supporting equipment of hydrogen generating system, in high pressure hydrogen storage and transportation, electron industry, utility industry, oil refining and chemical industry etc. The product can be used to purify the used hydrogen, realizing the recycle of the hydrogen, because of the function of purifying the hydrogen. Moreover, the product can also be applied in hydrogen refueling station. With the exploitation, utilization and promotion of the hydrogen and the development of the hydrogen fuel-cell vehicle, the hydrogen refueling station will become a very important part in every country’s infrastructure construction. The product will have a broad application prospect!