Boiling of the new low-GWP refrigerants R1234ze(Z) and R1233zd(E) inside a small commercial brazed plate heat exchanger. (August 2019)

• Record Type: Journal Article
• Authors: Longo, Giovanni A.; Mancin, Simone; Righetti, Giulia; Zilio, Claudio
• Is Part Of: International journal of refrigeration. Volume 104(2019)
• Page Start: 376
• Page End: 385
• Publication Date: 2019-08
• Subjects: GWP -- R1234ze(Z) -- R1233zd(E) -- Boiling -- BPHE; GWP -- R1234ze(Z) -- R1233zd(E) -- Ébullition -- Échangeur à plaques brasées (BPHE); Refrigeration and refrigerating machinery -- Periodicals; 621.56
• DOI: 10.1016/j.ijrefrig.2019.05.034
• Languages: English
• ISSNs: 0140-7007

Abstract

Highlights: This paper investigates R1234ze(Z) and R1233zd(E) vaporisation inside a BPHE. R1234ze(Z) exhibits boiling heat transfer coefficients 17–22% higher than R1233zd(E). R1234ze(Z) exhibits frictional pressure drops 7–32% lower than R1233zd(E). R1234ze(Z) and R1233zd(E) are very promising as low GWP fluids for HTHP and ORC. Abstract: This paper presents the heat transfer coefficients and the frictional pressure drops of R1234ze(Z) and R1233zd(E) boiling inside a commercial Brazed Plate Heat Exchanger (BPHE): the effects of heat flux / mass flux, saturation temperature / pressure, outlet conditions and fluid properties are investigated. The boiling heat transfer coefficients are controlled mainly by heat flux / mass flux and evaporator outlet conditions. The degrees of superheating at the outlet of the evaporator produces a degradation of the average boiling heat transfer coefficient in the whole evaporator, particularly for R1234ze(Z). The frictional pressure drops exhibit a quadratic dependence on refrigerant mass flux. Saturation temperature / pressure has a remarkable influence only on the frictional pressure drops. R1234ze(Z) exhibits boiling heat transfer coefficients higher and frictional pressure drops lower than those of R1233zd(E). There is a reasonable agreement between the saturated boiling heat transfer coefficients and the calculated values by two recent models for boiling inside BPHE.