Thermophysical properties and simulation of mixed refrigerants used for the hydrogen liquefaction process

R&D Focus Areas:
Liquid hydrogen

Lead Organisation:
University of Western Australia

Funding:
Future Energy Exports CRC

Status:
Active

Start date:
September 2023

Project summary description:
Current hydrogen liquefiers’ energy consumption is between (11.9 and 15.0) kWh/kgLH2, and liquefaction cost is between (2.5 and 3.0) US$/kgLH2 [1]. In comparison, liquefied natural gas’s (LNG) energy consumption is » 0.33 kWh/KgLNG and cost < 0.3 US$/kgLNG.

The high-power consumption and cost are partly due to using a low molecular weight refrigerant (H2), which requires multiple stages of compression. As a result, the use of mixed refrigerants (MRs) has been proposed for more efficient liquefaction cycles to be explored to lower the power and number of stages required for compression and thus reduce the total operating cost and capital cost. However, the experimental data situation for MRs (especially for ternary and higher order mixtures) at temperatures below 100 Kelvin and, consequently, the accuracy of existing models is poor.

Thus, the lack of reliable data and models for MRs thermophysical properties (such as density, heat capacity, speed of sound, enthalpy, and phase equilibrium) will obscure attempts to identify the most efficient liquefaction cycle. Moreover, the limitations and uncertainty of existing fluid property models implemented in process simulation tools, such as Aspen HYSYS, will increase design and operational margins.

This project will explore various liquefaction processes based on Brayton cycles, employing new mixed refrigerants mixtures of (hydrogen + helium + neon + nitrogen).

Further information:
23.RP2.0161 Thermophysical properties and simulation of mixed refrigerants used for the hydrogen liquefaction process, contact Future Energy Exports CRC for further information.

 

August 2023