Hydrate-based composition separation of R32/R1234yf mixed working fluids applied in composition-adjustable organic Rankine cycle

Abstract

Precise composition regulation of mixed working fluids is core to high performance composition-adjustable organic Rankine cycle (CA-ORC). However, most composition separation methods couldn't achieve precise regulation, limiting the application of CA-ORC. The hydrate-based composition separation proposed a promising avenue for precise regulation. In order to better apply to the CA-ORC, the separation characteristics of mixed working fluid hydrates should be clearly clarified, which remains to be a challenge. Facing the challenge, this study experimentally investigated hydrate-based composition regulation of R32/R1234yf mixed working fluid that possess both environmental and excellent thermodynamic properties. The separation characteristics of mixed working fluids were clarified, and the optimal separation operating conditions were analyzed covering a broad range of temperature (275.00 K–282.00 K) and pressure (0.30 MPa–0.54 MPa). The results show that hydrate-based composition regulation of R32/R1234yf can achieve excellent regulation performance, with composition change of R32 of 11.14–18.21 mol% in 90 min. Lower temperatures and higher pressures can lead to a better separation performance. Separation factor of R32 reach the maximum of 29.702, which is 4.12 times higher than the minimum. This study may provide a guidance to search energy-saving operating conditions for hydrate-based composition regulation and support its application in CA-ORC.