Nonflammable Low GWP Working Fluid for Organic Rankine Cycles

Abstract

Regulatory pressure has been increasing globally to address the issue of climate change. In particular, there are plans to reduce the use of hydrofluorocarbon (HFC) based working fluids across many applications, as HFCs are forecast to be significant contributors to global warming in the future. Therefore, there is a need to find low global warming potential (GWP) fluids suitable for organic rankine cycles (ORCs) in those systems where HFCs have historically been preferred. These are usually systems that require a non-flammable working fluid. A new ORC working fluid, cis-1,1,1,4,4,4-hexafluoro-2-butene, also called DR-2 (cis-CF3CH=CHCF3) has been developed which is nonflammable with very low GWP of 8.9 and an ozone depletion potential (ODP) of zero because it contains no chlorine or other halogen atoms other than fluorine. DR-2 also has a favorable toxicity profile based on testing to date. DR-2 is thermally stable in the presence of lubricant and metals, air and oxygen up to the maximum temperature tested of 250°C. DR-2 has a boiling point of 33.4°C and a relatively high critical temperature of 171.3°C, which result in relatively low vapor pressures and high cycle energy efficiencies. It can enable more environmentally sustainable ORC platforms to generate electrical power from widely available heat at higher temperatures and with higher energy efficiencies than incumbent working fluids.

Thermal stability and decomposition mechanism of HFO‐1336mzz(Z) as an environmental friendly working fluid: Experimental and theoretical study

“…The main physical property of HFO-1336mzz(Z) is listed in Table 1. Property of HFO-1336mzz(Z) [3,4]. High purity nitrogen (purity: 99.999%) and ethanol (purity: 99.97 wt%) are purchased from commercial suppliers to clean the research facility.…”

“…HFO‐1336mzz(Z) (CF 3 CHCHCF 3 ) is an environmental friendly refrigerant (ozone depletion potential [ODP] = 0, GWP = 8.9 [100 y], nonflammable, and low toxicity) to substitute HFC‐123 or HFC‐245fa in high‐temperature heat pump and organic Rankine cycle (ORC) system. Compared with conventional working fluids, HFO‐1336mzz(Z) has a remarkable performance in high‐temperature heat pump and ORC systems.…”

Selection of Organic Fluid Based on Exergetic Performance of Subcritical Organic Rankine Cycle (ORC) for Warm Regions

“…Considering the environment, researchers have studied the various low global warming potential (GWP) organic fluids for ORC [24][25][26]. Recently, Bahrami et al reviewed various ecologically friendly organic fluids for ORC applications [27].…”

Experimental and Density Functional Theory Studies on 1,1,1,4,4,4-Hexafluoro-2-Butene Pyrolysis

“…In the past decades, the working fluid with low global warming potential has attracted great attention [ 1 ]. HFO-1336mzz(Z) ( cis -CF 3 CHCHCF 3 ; 1,1,1,4,4,4-hexafluoro-2-butene; GWP = 2, ODP = 0; previously referred to as DR-2) is a kind of clear, colorless, lower toxic and non-combustible liquid (safety classification: A 1 ) [ 2 , 3 ]. As a novel type of low GWP working fluid with high-temperature chemical stability, HFO-1336mzz(Z) not only benefited the natural environment, but it can also enable 17% higher net cycle efficiencies over HFC-245fa [ 4 , 5 , 6 ].…”