Flow boiling heat transfer and pressure drop characteristics of R134a, R1234yf and R1234ze in a plate heat exchanger for organic Rankine cycle units

Abstract

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An experimental analysis of flow boiling and pressure drop in a brazed plate heat exchanger for organic Rankine cycle power systems

“…A first step towards an experimental database comprising experimental data of low temperature organic fluids vaporization at typical evaporating conditions for ORC power systems has been taken. Additional experimental data at high pressures using the same test rig with HFC-134a, HFO-1234yf, HFO-1234ze fluids can be found in Zhang et al [40].…”

“…Preliminary experimental results with HFC-134a as working fluids were presented in Desideri et al [39]. More detailed experimental data covering the vaporizaiton of HFC-134a, HFO-1234yf and HFO-1234ze at 60-80 • C are presented in Zhang et al [40]. In the present work the effects of mass flux, saturation pressure and evaporator outlet conditions on the two low critical temperature fluids, HFC-245fa and HFO-1233zd, were investigated.…”

Energy assessment of an R134a refrigeration plant upgraded to an indirect system using R152a and R1234ze(E) as refrigerants

“…Only R1234ze(E) reaches higher differences at 23.27ºC (+2.86 K) and 32.76ºC (+0.48 K) compared to the other refrigerants. This difference may be caused by the lower heat transfer coefficients of R1234ze(E) as it is explained by Zhang et al [36]. In fact, if the temperature difference between condensing and heat rejection temperatures is calculated, R1234ze(E) presents significant differences at low heat rejection temperatures which means a reduction in the overall heat transfer coefficient.…”

Condensation heat transfer and pressure drop characteristics of R134a, R1234ze(E), R245fa and R1233zd(E) in a plate heat exchanger

“…Similarly, the subcooled degree of the working fluids was controlled by regulating the temperature and flow rate of the chilled water. A previous research work [30] has performed a validation of the experimental facility, based on the measurement of the single-phase heat transfer coefficient of R1234yf in the evaporator. In addition, the heat loss in the condenser based on the R1233zd(E) complete condensation process (from superheated vapor to subcooled liquid) was tested in this work.…”