Design of a novel and efficient hydrogen compressor for wind energy based storage systems

• Water spray injection into a hydrogen compressor enables near-isothermal compression.
• Spray atomization creates large surface area for effective heat transfer.
• Cooling is primarily produced by the sensible heat of water droplets.
• Eulerian–Lagrangian model is used along with adaptive mesh refinement for accurate simulation of water spray cooled hydrogen compressor.

In a hybrid wind power system, the excess wind energy is stored in the form of compressed hydrogen. Wind turbine generates electricity from the wind. The excess power (after meeting the load requirements) is used to generate hydrogen using an electrolyzer. The generated hydrogen is compressed using a compressor and sent to storage in a high pressure storage tank. The compressor should be operated at near isothermal conditions to reduce the power consumed by the compressor, thereby increasing the efficiency of the system. This paper deals with CFD modeling of a novel water spray cooled reciprocating hydrogen compressor which provides efficient cooling of the system during compression. Water is sprayed directly into the compressor cylinder during the compression stage. The water spray breaks into droplets, which provides large surface area to absorb the heat of compression thereby reducing the temperature. The heat capacity of water being order of magnitudes higher than that of hydrogen provides efficient cooling of the compressed gas with small water to hydrogen volumetric ratio. The concept of water spray cooling during compression is demonstrated through a three dimensional computational fluid dynamics (CFD) simulation.