1,3,3,3-Tetrafluoropropene


1,3,3,3-Tetrafluoropropene is a hydrofluoroolefin. It was developed as a "fourth generation" refrigerant to replace fluids as R-134a and as a blowing agent for foam and aerosol applications. The use of R-134a is being phased out because of its high global-warming potential. HFO-1234ze has zero ozone-depletion potential, a very low global-warming potential, even lower than CO, and it is classified by ANSI/ASHRAE as class A2L refrigerant.

Uses

The increasing concerns about global warming and the related possible undesirable climate effects have led to an increasing agreement in developed countries for the reduction of greenhouse gas emissions. Given the relatively high global warming potential of most of the hydro-fluoro-carbons, several actions are ongoing in different countries to reduce the use of these fluids. For example, the European Union’s recent F-Gas regulation specifies the mandatory GWP values of the refrigerants to be used as working fluids in almost all air conditioners and refrigeration machines beginning in 2020.
Several types of possible replacement candidates have been proposed so far, both synthetic and natural. Among the synthetic options, hydro-fluoro-olefins are the ones appearing most promising thus far.
HFO-1234ze has been adopted as working fluid in chillers, heat pumps, and supermarket refrigeration systems.
It has been demonstrated that HFO-1234ze can not be considered as a drop-in replacement of HFC-134a. In fact, from a thermodynamic point-of-view, it can be stated that:
– The theoretical coefficients of performance of HFO-1234ze is slightly lower than HFC-134a one;
– HFO-1234ze has a different volumetric cooling capacity when compared to HFC-134a.
– HFO-1234ze has saturation pressure drops higher than HFC-134a during two-phase heat transfer under the constraint of achieving the same heat transfer coefficient.
So, from a technological point-of-view, modifications to the condenser and evaporator designs and to compressor displacement are needed to achieve the same cooling capacity and energetic performance of HFC-134a.