A novel vortex tube-based N2-expander liquefaction process for enhancing the energy efficiency of natural gas liquefactionMuhammad Abdul Qyyum, Feng Wei, Arif Hussain, Wahid Ali, Oh Sehee and Moonyong LeeE3S Web Conf., 22 (2017) 00140DOI: https://doi.org/10.1051/e3sconf/20172200140